Article

Automobile Brake-by-Wire Control System Design and Analysis

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Abstract

The automobile brake-by-wire (BBW) system, which is also called the electromechanical brake system, has become a promising vehicle braking control scheme that enables many new driver interfaces and enhanced performances without a mechanical or hydraulic backup. In this paper, we survey BBW control systems with focuses on fault tolerance design and vehicle braking control schemes. At first, the system architecture of BBW systems is described. Fault tolerance design is then discussed to meet the high requirements of reliability and safety of BBW systems. A widely used braking model and several braking control schemes are investigated. Although previous work focused on antilock and antislip braking controls on a single wheel basis, we present a whole-vehicle control scheme to enhance vehicle stability and safety. Simulations based on the whole-vehicle braking model validate a proposed fuzzy logic control scheme in the lateral and yaw stability controls of vehicles.

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... Reduced weight [4,5]; • Easy assembly [4,6]; • Modularization [6]; • Lower power consumption [5]; • Enhanced vehicle stability (dynamic brake force distribution, faster brake response, etc.) [4,7,8]; • Easier cooperative regenerative braking [8]. ...
... Reduced weight [4,5]; • Easy assembly [4,6]; • Modularization [6]; • Lower power consumption [5]; • Enhanced vehicle stability (dynamic brake force distribution, faster brake response, etc.) [4,7,8]; • Easier cooperative regenerative braking [8]. ...
... Reduced weight [4,5]; • Easy assembly [4,6]; • Modularization [6]; • Lower power consumption [5]; • Enhanced vehicle stability (dynamic brake force distribution, faster brake response, etc.) [4,7,8]; • Easier cooperative regenerative braking [8]. ...
Article
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A growing interest in Electromechanical Brakes (EMBs) is discernible in the automotive industry. Nevertheless, no EMBs have ever been deployed for series production, although countless publications have been made, and patents have been filed. One reason for this is the need for the optimization of functional safety. Due to the missing mechanical/hydraulic link between the driver and the actuator, sophisticated concepts need to be elaborated upon. This paper presents the current state of the art of safety concepts for EMB systems (only publicly available publications are reviewed). An analysis of current regulatory and safety requirements is conducted to provide a base for design options. These design options are explored on the basis of an extensive patent and literature research. The various discovered designs are summarized and analyzed according to their (a) EMB actuators; (b) control topology; (c) energy supply; and (d) communication architecture. This paper concludes by revealing the weak points of the current systems.
... Fig. 2. Freewheel body diagram. Adapted from [6] Where and are respectively the radius and inertia of the wheel (approximated as being a homogeneous cylinder), is the applied torque, and are respectively the longitudinal and vertical forces, is the angular velocity and is, the speed of the vehicle. ...
... In order to estimate them, the model proposed in [8] was adopted. In this model, as shown in equations (15) and (16), the longitudinal forces are estimated as a function of the longitudinal slidinggiven by equation (5) [6]. (24) and (25) are estimated as a function of the slip angles given by equations (6) to (9) [9]. ...
... Free Body Diagram of the vehicle. Adapted from[6] ...
Conference Paper
The Automatic Emergency Braking (AEB) systems in vehicles is one of the technologies suggested by NHTSA to be included in vehicles by default. This article presents the dynamic model of the vehicle that should be considered to design control of EAB system. After that, the design of a classic controller is presented, following of some results of simulations, which let to identify variables to measure the comfort of automatic braking, and when and in which conditions the ABS systems act over an action of AEB. Finally, the Architecture of the implementation of the braking over CAN Networks is presented.
... The development trend of drive-by-wire system in automotive industry is first to assist the driver [2] by providing him additional mechanism to control the vehicle, then replace the actual hydraulic and mechanical parts of automobile. X-by-wire system includes brake-by-wire, steer-by-wire, active suspension, direct fuel injection, electrically assisted power steering and electronic throttle control etc. Brake-By-Wire (BBW) system replaces the need of hydraulic system and mechanical assembly with electropneumatic actuators and communication network [3]. Under some critical situations, the driver of the vehicle has no control on stability of the vehicle, so there is a need of automatic stability controller in the vehicle, which will provide an automatic control during panic situation. ...
... .3 Brake-by-wire system testingFigure 4.4: Flow Chart for response time of brake-by-wire system ...
... Related work of brake by wire system based on nonlinear control theory can be found in [1]. A fuzzy logic fault tolerant control architecture was proposed in [2] that stabilizes the lateral motion of the vehicle. This paper details the process of designing a control loop making brake by wire an actual system from the autonomous dream. ...
... The usual way of solving the ‫ܪ‬ ஶ control problem is the use of Riccati equations or LMI [3,4]. This leads to the design of the control law ‫ݑ‬ that is solution of the suboptimal problem (2). A bisection algorithm is then used to approach the minimal value of ߛ. ...
Conference Paper
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A world of autonomous cars is at our doorstep, arising new challenges for engineers. The sentence: "Safety first!" is more than valid in this field. One of the main safety features of a car is the braking system. However, the brake by wire concept is rather new and there are several issues with it. Our article deals with the controller design phase for a smart braking system, where the braking actuator is modeled as a system having multiple uncertainty sources. The design is verified using simulations and the final verification phase includes testing on a board model of the actuator system.
... The transmitter transmits the IR waves, and when these waves strike an obstacle, the signal is sent back to the receiver [2]. After the receiver interprets the signal, the signal is further sent to the Arduino and then to the relays, which will initiate the braking of the vehicle with the help of DC motor and brake wires [3,4]. ...
... Disc brake[4] ...
... Therefore, it gradually becomes the research hotspot in the fields of automotive safety [9]. BBW uses electric wires and electrical signals to convey the driver's braking intentions; and uses motors, drivers and transmission components to provide braking force,as shown in Figure 1 [10]. When the vehicle needs to brake, the driver steps on the electronic brake pedal simulator. ...
... BBW is a key technology to improve vehicle safety in the future, so the design, manufacture and maintenance of BBW should be perfect. The current research on BBW mainly focuses on two points: one is to design actuator with excellent structure and compact size [10], [17]; the other is to develop control strategy with superior performance [18], [19]. After years of research, a large number of theoretical and experimental results have been obtained. ...
Article
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The brake-by-wire actuator was considered to be the next generation of vehicle brake, which uses cables to transmit signals and energy, and uses electric motor instead of hydraulic element or pneumatic element. This paper designs a new type of brake-by-wire actuator based on the special linear motor. First, the structure, composition and working principle of the linear motor are explained. Secondly, the caliper structure and amplification mechanism of the actuator are designed. Thirdly, the controller and control strategy based on dSPACE platform are introduced in detail. Finally, the electromechanical parameters of actuator were identified, and the experiment of the linear motor and brake-by-wire actuator were completed. The experiment results show that the new actuator has the advantages of fast braking response, low control difficulty and high control accuracy, etc. In conclusion, this paper provides a new design scheme for the brake-by-wire actuator, and has the potential to further research and replace the traditional hydraulic braking system.
... Presently, the main research focuses on single-wheel anti-lock braking control. In fact, the fuzzy logic controller can be used for vehicle longitudinal and lateral stability control [75]. The target slip assignment algorithm that is based on fuzzy logic controller and direct yaw moment controller can also maintain the vehicle stability [51]. ...
... BBW is able to precisely adjust the braking force of each wheel, so that the braking force can be flexibly distributed between the axles or between the wheels [75,93]. The classic braking force distribution scheme of hydraulic brake system only considers the adhesion coefficient, while BBW can redistribute the braking force of the steering vehicle. ...
Article
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This paper reviews and summarizes the development, key technologies, and application of brake-by-wire (BBW) actuators. BBW is the technology orientation of future vehicle brake system. The main feature of BBW is to replace some of the mechanical and hydraulic components of traditional brake system with electronic control components, and use cables and wires to transmit energy and signals. BBW actuators have outstanding advantages, such as fast response, accurate control, and compact structure. They are easy to integrate with active safety functions and they are easily matched with the regenerative braking systems of electric vehicle. First, this paper summarizes the classification, characteristics, performance, and architecture of BBW actuators. Subsequently, the braking process regulation of vehicle is considered to be the main target, which is summarized from two aspects of actuator regulation and braking force distribution. The state estimation algorithm and control algorithm applied to these actuators are summarized and analyzed, and the development trend, challenges, and schemes of the braking force distribution are proposed. The development and research trend of braking force match strategies between the regenerative brake system and BBW system are also analyzed and summarized. The further electrification and intelligence of vehicle demand BBW’s braking force control method and distribution method must have higher control accuracy, stronger robustness, and wider adaptability, and the effects on braking comfort and handling stability must be further discussed.
... By-wire technology in the automotive industry is considered a frontier technology that allows many traditional automobile subsystems to switch to electronic elements and control system instead of mechanical and hydraulic components, especially for electric vehicles (Mingfei, 2012;Xiang et al., 2008;Seidel, 2009;Anwar and Zheng, 2007). The use of by-wire technology is due to its various merits and advantages such as it reduces vehicle speed, increases vehicle performance and allows to involve integrated control systems. ...
... • Vehicle mass (m), wheel radius (R wheel ) and moment of inertia of the wheel (I) are, respectively, equal to m = 1300 kg, R wheel = 0.3 m and I = 0.6 kg.m 2 (Xiang et al., 2008). ...
Article
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The current study presents the derivation of mathematical modelling of anti-lock brake system solely from brake-by-wire perspective. The study also proposes permanent magnet DC (PMDC) motor to perform suitable braking action which is selected based on predetermined electric actuator characteristics. The brake system and electric motor specifications are then designed, taking into consideration maximum magnitude of electric vehicle power supply. In addition to that, a study case based on proportional integral derivative (PID) controller is carried out to further examine performance behaviour of the proposed mathematical model and the validity of computational specifications for brake system design as well as the PMDC motor. Simulation analysis and investigation which are conducted in MATLAB software revealed efficient operating brake system that leads to obtain desired control signal successfully with outstanding performance. Furthermore, the result output behaviour of the plant mimics predetermined brake system analysis which ensures the validity of the proposed mathematical design.
... If hydraulic lines are replaced with electrical systems, the reliability could be improved. Brake by wire technology overcame the limitations of the hydraulic system and improved the brake system [12]. The by wire brake systems started to emerge with the emergence of electrical drivers and actuators that support by Wire technology [13]. ...
... The reaction forces of the brake motor are measured using RFOB, as shown in Figure 3 (a). The force can be calculated using (12), where Ia is the brake motor current and Kfb motor constant of the brake. ...
Article
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"By wire" technology merged into multiple vehicular subsystems, including gear changing, drive, and braking systems. The brake by wire system is developed to overcome the problems associated with the integration of mechanical and hydraulic systems in novel vehicular systems. Even though brake by wire systems has potential advantages, the conventional brake systems' tactile sensation will be removed if migrated to the electrical by wire control scheme. This paper proposes a novel control mechanism that provides amplification of force, scaling of position replication, and a virtual spring-damper based pedal retraction which provides bilateral brake force feedback to the driver's pedal similar to the hydraulic brake system. The proposed system performance was simulated and tested using a bilateral teleoperation system with disturbance observers (DOB) and reaction force observers (RFOB). The proposed system provides pedal force amplification and brake force feedback to the driver's pedal using RFOBs. The virtual spring retracts the brake pedal, similar to a mechanical pedal retraction system. The system simulation and experimental results provide evidence of the proposed system's force amplification, position scaling, and pedal reaction capabilities.
... I n order to meet the new requirements of brake system for EVs and intelligent vehicles, brake system need to have the function of decoupling the pedal force with the wheel brake force for regenerative braking, and the function of active braking for Advance Driver Assist system (ADAS) such like Autonomous Emergency Braking (AEB) [1]. ...
... The authors have worked on perception algorithms for the purpose of enabling autonomy in vehicles for more than 25 years. References [7][8][9][10] pertain to some of the widely referenced papers in this area. The simulation model presented in this paper incorporates similar algorithms. ...
Conference Paper
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This paper describes a simulation model for autonomous vehicles operating in highly uncertain environments. Two elements of uncertainty are studied-rain and pedestrian interaction-and their effects on autonomous mobility. The model itself consists of all the essential elements of an autonomous vehicle: model, the paper presents results that assess the autonomous mobility of a Polaris GEM E6 type of vehicle in varying amounts of rain, and when the vehicle encounters multiple pedestrians crossing in front. Rain has been chosen as it impacts both situational awareness and trafficability conditions. Mobility is measured by the average speed of the vehicle. This work is part of MDAS.ai, a multidisciplinary autonomous shuttle development project. 2
... This mechanical linkage can decrease the efficiency of the engine. In recent years, the mechanical linkage has been replaced in modern vehicles with an electronic connection, commonly known as an electronic throttle [1][2][3]. In an electronic throttle, the accelerator pedal is linked to the engine throttle using a DC servomotor, which can improve both the vehicle's drivability and fuel economy. ...
Article
To achieve more precise positioning of the electronic throttle plate, a nonlinear backstepping tracking control strategy is presented in this paper. In contrast to the existing control schemes for electronic throttles, the input saturation and unknown external disturbances are explicitly considered in the tracking control design. The difficulties in controlling an electronic throttle include the strong nonlinearity of the spring and friction as well as the unknown external disturbance. In particular, the valve plate angle is adjusted by the control input voltage of the driving motor, and the input voltage is limited to a certain range. Therefore, input saturation problems exist in the control system for an electronic throttle. To overcome the abovementioned difficulties, an auxiliary design system is presented to handle the input saturation, and its state is applied in the proposed control design. A sliding-mode control term is also utilized in the tracking controller to counteract the unknown external disturbance. The proof and analysis show that the satisfactory tracking performance of the valve plate angle can be achieved by using the designed control scheme for the electronic throttle system in the presence of input saturation and unknown external disturbances. Simulation studies and results are provided to illustrate the desired performance of the proposed nonlinear tracking controller.
... As a trend of future development of modern vehicles, the X-by-Wire technology has been playing a pivotal role in automobile industry. By the way of utilizing electrical actuators or manipulators and electronic control units to replace conventional mechanical linkages, the X-by-Wire technology implemented in automobile industry is divided into different aspects with respect to different parts of a vehicle, such as brake-by-wire [1], [2], throttle-by-wire [3], shift-by-wire [4] and steer-by-wire (SbW) [5], [6] technologies. The basic idea of SbW is to remove the conventional steering column between the steering wheel and the pinion-and-rack system, and then to utilize a steering motor to generate the steering torque to steer the front wheels and a feedback motor to provide reactive torques for drivers to perceive the road information. ...
... As this approach is only based on quarter car model, it can be further extended to full vehicle model, by which weight transfer effect between front and rear wheels can be better considered. With the development of intelligent vehicle as well as transportation, brake-by-wire is emerged as a promising braking control scheme in modern vehicles [20]. By using communication network such as CAN, the brake-by-wire system offers easy connection with other vehicle control system. ...
Article
Full-text available
This paper proposes a hierarchical braking torque control system design over CAN for electric vehicle with four in-wheel motors. Based on nonlinear tyre-road friction estimation, an adaptive braking torque control scheme is devised in the upper-level controller to simultaneously regulate the wheel slip ratio for both front and rear wheels. While in the lower-level controller, a frequency-depended braking torque allocator is developed to dynamically distribute the braking torques command from upper-level controller into friction braking torque and regenerative braking torque. A braking supervisor is established to enable or disable proposed hierarchical braking controller according to wheel slip ratio as well as vehicle speed condition. To avoid undesired discontinuities in braking torque signal when proposed braking controller is enabled abruptly, initial value of the estimated tyre-road friction is rescaled additionally. Dedicated CAN bus module is built by using SimEvent toolbox, by which vehicle states as well as control signals can be transmitted and shared. Co-simulation by using MATLAB / Simulink and CarSim is conducted to demonstrate the effectiveness of the proposed hierarchical braking torque controller. Random CAN-induced delays are considered in the braking control process, by using which the robustness of the proposed hierarchical braking controller is further verified.
... Though the maximum slip ratio magnitude seems a small value, the main cause for vehicle-wheel deceleration is considered since friction force between road surface and wheel surface principally depends on the slip ratio magnitude even though if the slip ratio possesses very small magnitude that may reach to mili-slip ratio. This fact is clearly observed from Figure 6(b), especially within the time interval [2,4] seconds, where the slip ratio of fuzzy-PID controller output response (blue line) has larger magnitude than PID output response (red line) by mili-values. This slight divergence that fuzzy-PID created, by trivial increases in slip ratio magnitude, leads to dramatically improve and enhance output response by decreasing vehicle stopping time 60% as compared to conventional PID controller. ...
... N owadays, the electric and intelligent vehicles have put forward new requirements for braking systems, such as the independence of vacuum [1], automatic or active braking [2], brake-by-wire [3] and so on. However, the traditional brake system equipped with vacuum booster fails to meet these requirements. ...
... Sohel Anwar adopted nonlinear sliding mode control method to control brake by wire system on low adhesion coefficient road surface, system noise and vibration was reduced [6]. W. Xiang used fuzzy logic control method to control lateral stability and yawing stability of brake by wire system [7]. P. Krishnamurthy and W. Lu designed robust controller for brake by wire system [8]. ...
Article
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Existing electronic mechanical brake by wire system has several disadvantages. For instance, system actuators are complex, response speed slower, larger vibration noise, etc. This paper discusses a new type brake by wire system based on giant-magnetostrictive material. The new type brake by wire system model was set up under Matlab/Simulink software environment. PID control method was used to control the brake by wire system. Simulation results shows that the new type brake by wire system achieves better braking performance compared with hydraulic braking system. This work provides a new idea for researching automobile brake by wire system..
... [25,27,28]. The instability studies have indicated that it has a lower propensity to instability and also, at the low range of instability frequencies have shown that is more reliable [27][28][29][30]. ...
Article
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This paper presents an attempt to evaluate the sensitivity of lattice parameters on the contact pressure instability of newly lattice brake disc. The instability characteristics are investigated through theoretical representation, modal analysis experiments, and nonlinear finite element thermo-mechanical analysis. Lattice properties are defined concerning the lattice truss angle geometry in the unit cell and periodicity of the lattice cell on the lattice plate. Motion dynamics of lattice plate concern the principal coordinates on the rotating disc are presented to use in the braking system. The modal behaviour of vanned and lattice brake disc/pad systems are defined through experimental modal analysis at free-free boundary conditions, and results are used as inputs of nonlinear finite element models as it goes through a partial simulation of the SAE J2521 drag braking noise test. Subsequently, the dynamic instability analysis of the brake disc is detailed by using the complex eigenvalue extraction technique concerning the contact pressure and lattice parameters effect. The sensitivity analysis of the brake instability respected to the mass fraction factor and relative density of the lattice structure is presented by using the average standard deviations of the contact pressure force. The likelihood of instability occurrence is quantified by definition of a single indicator derived from the system eigenvalues. The analysis indicates that the higher relative density with lower mass fraction factor of lattice structure is led to a higher temperature at the disc and pad surface. Mutually, the higher mass fraction factor with lower relative density is led to the lower temperature. The maximum contact pressure is observed in the model with less mass fraction factor and more uniform pressure distributions are observed at higher values of the mass fraction factor. The instability analysis points out that high instability frequencies are predicted at lower mass fraction factor and higher relative density.
... Related work of brake by wire system based on nonlinear control theory can be found in (Tanelli et al., 2008). Fuzzy logic fault tolerant control architecture was proposed in (Xiang et al., 2008) that stabilizes the lateral motion of the vehicle. A cooperative method involving the human driver and the assistive system; the based on fuzzy approach is presented in (Nguyen et al., 2015). ...
Article
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This paper deals with the robust control system design and implementation of a brake actuator for a smart car. To deliver robust performance, an H∞ controller had been chosen for the task. This allows excellent disturbance rejection while requiring low computational needs. In order to realize the controller a nominal model of the system has been identified, then, the parameter uncertainties were taken into account to find the stabilizing controller. The brake system consists of a low level H∞ controller sustaining robustness, a mid-level serial compensator for effective setpoint tracking and a high level supervisory control logic to deliver a reliable system. The implementation was tested and verified on a test bench using rapid prototyping tools and HIL methods.
... Sohel Anwar adopted nonlinear sliding mode control method to control brake by wire system on low adhesion coefficient road surface, system noise and vibration was reduced [4]. W. Xiang, used fuzzy logic control method to control lateral stability and yawing stability of brake by wire system [5]. Simulation research of pedal force has been made , it provided a basis for the simulation design of pedal force. ...
Article
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In this paper, H type brake by wire system based on giant-magnetostrictive material is designed from two aspects of hardware and software. System principle prototype is manufactured. Hardware circuit mainly includes the Sepic circuit, current detection circuit, over current protection circuit, PWM driver protection circuit. Circuit parameters can be obtained through by theoretical calculation. Pedal sensor signal is taken as main control variable, look-up table method is used for brake by wire system. The experimental results show that the system can meet the braking requirements. It proves the feasibility of the scheme.
... General electronic BBW system is shown as Fig. 4 [10]. Generally, it consists of BPIU, EBCM, fourwheel WBCU and communication network. ...
Article
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Brake-by-wire (BBW) system is the key system to ensure the safety and stability control of intelligent vehicle chassis. How to evaluate the BBW systems to meet the safety design requirements is one of the important links of system design. This article takes the BBW system as an example to illustrate the basic process of the safety assessment of intelligent vehicle. The fault tree analysis (FTA) method is used to quantitatively evaluate the failure status of the complete loss of the main brake function, and the fault tree analysis process is detailed. The results show that FTA plays an important role in guiding the design of system architecture. With the help of the importance index, we can quickly find out the weaknesses in the system architecture, when the probability of the failure state of the automobile brake-by-wire system cannot meet the ASIL requirements. Furthermore, effective countermeasures can be taken to optimize the design of the system architecture. Finally, the failure probability corresponding to the failure state of the car’s brake-by-wire system is reduced to 7×10 ⁻¹⁴ .
... BBW systems suffer from unpredictable failures during operation since the traditional mechanical or hydraulic connections between pedal and wheel actuators have been replaced by cables and wires, and the construction and control of BBW systems have become more complex [61]. Therefore, there is still a lot of room for development in the integrated control of BBW systems in order to solve the existing problems of current technology and to meet the future demands for braking performance. ...
Article
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Intelligent connected electric vehicles (EVs) are widely considered as a trend in the global automotive industry to make transportation safer, cleaner and more comfortable. As an important component of intelligent connected EVs, the brake-by-wire (BBW) system is the key to determining the performance of the vehicle and the efficiency of braking energy recovery. BBW systems are showing great promise in the area of vehicle braking due to the increasing requirements on safety and energy efficiency of vehicles. In recent years, BBW systems have undergone great changes in terms of structure and control methods, not only increasing safety and energy recovery efficiency, but also integrating more functions. Although important advancements have been achieved in this field, these works have not been fully summarised. This paper surveys and summarizes the research in literature to bring topical information to the field of intelligent transportation systems. The objective of this study is to present an overview of both the development trend and key technologies of the BBW system for intelligent connected EVs. Firstly, the development, structure and core components of BBW system are described. Secondly, the control method and control strategy of BBW system are analyzed. As much as the system shows great promise, the problems existing on its current technology should be addressed as well. Finally, some important countermeasures are proposed to solve the existing technical problems of the BBW system.
... In most modern road vehicles there is still a mechanical coupling between brake pedal and brakes, but so-called "brake-by-wire" designs have started to appear in cars in the recent years. These modern designs can improve the braking efficiency and stability of the vehicle [219]. The six reactors contained in the PowerTrain reactor jointly coordinate the control of the brakes and the engine. ...
Thesis
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Actors have become widespread in programming languages and programming frameworks focused on parallel and distributed computing. While actors provide a more disciplined model for concurrency than threads, their interactions, if not constrained, admit nondeterminism. As a consequence, actor programs may exhibit unintended behaviors and are less amenable to rigorous testing. The same problem exists in other dominant concurrency models, such as threads, shared-memory models, publish-subscribe systems, and service-oriented architectures. We propose “reactors,” a new model of concurrent computation that combines synchronous-reactive principles with a sophisticated model of time to enable determinism while preserving much of the style and performance of actors. Reactors promote modularity and allow for distributed execution. The relationship that reactors establish between events across timelines allows for: 1. the construction of programs that react predictably to unpredictable external events; 2. the formulation of deadlines that grant control over timing; and 3. the preservation of a deterministic distributed execution semantics under quantifiable assumptions. We bring the deterministic concurrency and time-based semantics of reactors to the world of mainstream programming languages through Lingua Franca (LF), a polyglot coordination language with support (so far) for C, C++, Python, and TypeScript. In LF, program logic is given in one or more of those target languages, enabling developers to use familiar languages and integrate extensive libraries and legacy code. The main contributions of this work consist of a formalization of reactors, the implementation of an efficient runtime system for the execution of reactors, and the design and implementation of LF.
... The optimal braking safety of the vehicle cannot be guaranteed. 3 Intelligent/automated vehicles, which represent the most advanced technology in the vehicle industry, are integrating the science and technology of the whole society to ''innovate'' at an extremely fast speed. However, the important hardware in vehicles, such as the x-by-wire execution systems that are coordinated with the controller decisions in intelligent/automated vehicles, has not made satisfied progresses. ...
Article
Electro-mechanical brake (EMB), driven by a motor to push the brake pads to clamp the brake disk for braking, is considered as the future of vehicle braking system, because of its simple structure and controllable braking force. However, EMB must face the problem of motor blocking when it works in a long-time continuous braking condition. When the motor is blocking, the current in the coil windings is large enough to burn the motor down, leading to the failure of EMB, which is a great threat to driving safety. To solve the problem, a new brake-by-wire actuator featuring magnetorheological (MR) clutch (MRC) – an EMB combining with an MRC, i.e., BBW-MRC, is presented in this paper. Specifically, the BBW-MRC is composed of a driving motor, an MRC, a planetary gear reducer, a ball screw, brake pads, and a brake disk. The motor output is transmitted to the MRC through the reducer, and it is controlled in real-time, continuously, and as expected by the MRC via controlling its applied current. The ball screw is driven by the MRC and pushes the brake pads to clamp the brake disk to realize braking in time. The small-scaled BBW-MRC system and the corresponding test bench are developed, and a hierarchical control strategy applied to the BBW-MRC system is designed. Based on the test bench, a series of tests are carried out on the BBW-MRC system, including the stability test of the BBW-MRC system under a long-time braking condition, the braking force response test of the BBW-MRC, and the braking force tracking test. Research results show that: (1) the BBW-MRC system has a quick and accurate performance to track desired braking forces; (2) under long-time braking conditions, the braking force keeps stable and the surface temperature of the motor has a normal change; and (3) the braking force response time has a 53.5% improvement over the EMB that driven by the motor directly.
Article
Brake-by-wire (BBW) is a critical technology in modern automotive and lays the solid foundation for intelligent vehicles. A control strategy to take full advantages of this system both in active brake and conventional boosting brake is essential for the BBW system, which is a challenging issue because of its complex structure and high requirement for rapid dynamic response and control accuracy. To get satisfied performance and control effect, this paper designs a new type of electric booster installing on the electro-hydraulic brake (EHB) system which can realize active brake control and brake boosting simultaneously, then a synthetic control architecture special for this system is put forward. Firstly, system principle and detailed modelling are given. Then an adaptive dual-loop brake pressure control approach is proposed where a modified PID controller is used as the outer control loop to track the desire pressure and an inner loop named adaptive current control is employed to guarantee the brushless direct electric motor (BLDC) performance of tracking current considering the parametric variation and system uncertainties. Besides, the stability of the inner loop control is proved. Meanwhile, a user-defined brake boosting framework is designed to realize electric boosting brake. Simulation and experimental validation are implemented to demonstrate the feasibility of the system and the effectiveness of the control strategy design eventually, manifesting that the proposed BBW system and its control strategy can obtain satisfied performance.
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This paper focuses on clamping force control of electronic wedge brakes without additional sensors for cost-effectiveness and system simplicity. Brake-by-wire systems can be used for enhanced, safe braking of intelligent and environmentally friendly vehicles such as gas-electric hybrid and electric vehicles. For implementation of the electronic wedge brake, the clamping force should be controlled properly even though model uncertainty and parameter variations exist due to the environment or system characteristics changes, e.g., temperature variations, pad wear, and nonlinear friction. In this paper, the electronic wedge brake is modeled to include the wedge dynamics as well as the nonlinearities such as backlash and friction in mechanical connections and clearance between the brake disk and pad. An on-line status monitoring algorithm using the simplified mathematical models is designed to estimate the mechanical system parameters. Based on the mechanical parameters estimated initially and the estimated clamping force, a sliding-mode control algorithm is proposed to achieve the robust control performance. The performance of the proposed monitoring and control algorithm is verified through simulations using Matlab/Simulink. Additionally, the proposed algorithm is validated experimentally using a hardware-in-the-loop simulation test bench equipped with the prototype electromechanical brake and electronic wedge brake.
Article
This paper proposes a design approach for the network configuration of brake-by-wire (BBW) systems using the FlexRay communication protocol. Owing to the absence of mechanical or hydraulic back-ups, the BBW system needs to be highly reliable and fault-tolerant. The FlexRay network is shown to be very effective for such requirements of BBW systems by using hardware in-the-loop simulation (HILS), which allows developing and testing various algorithms and faithfully reproduces the actual system. The FlexRay protocols are designed using the FIBEX configuration tool appropriately for the control of BBW systems, and they are analyzed using the FlexRay communication monitoring tool. The results of HILS illustrate that the braking performance of a controller area network (CAN)-based network and that of a FlexRay-based network for BBW systems are very similar, however, the FlexRay-based network system is more reliable and ensures better fault diagnosis by monitoring more variables.
Article
Purpose The purpose of this paper is to design an improved parallel regenerative braking system (IPRBS) for electric vehicles (EVs) that increases energy recovery with a constant brake pedal feel (BPF). Design/methodology/approach The conventional hydro-mechanical braking system is redesigned by incorporating a reversing linear solenoid (RLS) and allowed to work in parallel with a regenerative brake. A braking algorithm is proposed, and correspondingly, a control system is designed for the IPRBS for its proper functioning, and a mathematical model is formulated considering vehicle drive during braking. The effectiveness of IPRBS is studied by analyzing two aspects of regenerative braking (BPF and regenerative efficiency) and the impact of regenerative braking contribution to range extension and energy consumption reduction under European Union Urban Driving Cycle (ECE). Findings IPRBS is found to maintain a constant BPF in terms of deceleration rate vs pedal displacement during the entire braking period irrespective of speed change and deceleration rate. The regenerative ratio of IPRBS is found to be high compared with conventional parallel regenerative braking, but it is quite the same at high deceleration. Originality/value A constant BPF is achieved by introducing an RLS between the input pushrod and booster input rod with appropriate controller design. Comparative analysis of energy regenerated under different regenerative conditions establishes the originality of IPRBS. An average contribution ratio to energy consumption reduction and driving range extension of IPRBS in ECE are obtained as 18.38 and 22.76, respectively.
Conference Paper
A new brake-by-wire system based on direct-drive electro-hydraulic brake (DDEHB) unit was designed for vehicle to improve braking performance. A comprehensive brake-by-wire system including this new unit which was set up and its structure and principles were introduced detailed in part II. Then the dynamic model of DDEHB was studied by detailed studying the movement of piston and plunger when braking in part III. At last a Simulink model based on section III was established using Mathlab/Simulink and Mathlab/Stateflow in part IV, and the reliability of model was testified by simulation. The simulation results showed that this novel brake unit can rapidly respond and improve braking performance significantly.
Article
Advances in real-time, embedded and distributed systems along with control and communication theory have catalyzed the rapid emergence of cyber-physical systems such as a self-driving car. The importance of fault-tolerance support on a cyber-physical system (CPS) has been greatly emphasized by recent research due to the nature of CPS that senses its surroundings, processes sensor data, and reacts using its actuators. In order to tackle this challenge, we proposed SAFER (System-level Architecture for Failure Evasion in Real-time Applications) in our previous work. SAFER is able to tolerate fail-stop processor and/or task failures for distributed embedded real-time systems. One of its limitations, however, is that SAFER is not capable of tolerating a failure of a processor with a dedicated connection to an actuator. This paper provides a method that relaxes this limitation by (1) deploying a small piece of hardware to avoid a dedicated connection between a processor and an actuator, (2) adding a software module that monitors and controls the hardware, and (3) enhancing the failure detection and recovery mechanisms of SAFER to support these changes. The detailed implementation and evaluation of the SAFER extension is on-going work.
Article
This paper presents a novel sensor-less steering torque control method for applications to the steer-by-wire system. A steer-by-wire system has not any mechanical link to connect a steering wheel and a rack and pinion gear module. Instead of mechanical devices, two electric motors are used on each side. A one motor is attached to the steering wheel and the other is set on rack and pinion. The motor on the steering wheel works as a deliverer between a steering torque and load torque from the road. In this paper, we focus on motion control related to the steering feel based on impedance control. Therefore, the model of rack and pinion is not considered in this work. In most power steering systems, a torque sensor is used to set impedance effect on driver’s steering feel. In this paper, we proposed a novel steering control method without using any torque sensors. The effectiveness of a proposed method is confirmed from experimental results.
Article
The performance of automated vehicle can be greatly improved by enabling vehicle-to-vehicle communication. An example of such applications is Cooperative Adaptive Cruise Control (CACC) along the highway. Although the adoption rate of vehicular connectivity is predicted to grow rapidly, CACC can only benefit vehicles that are both connected and automated. To take a full advantage of vehicular connectivity, a human-in-the-loop Connected Cruise Control (hCCC) algorithm is developed for human-driven connected vehicle. In hCCC, the human driver remains engaged in the longitudinal control of the vehicle, and hCCC controller applies additional acceleration/deceleration on top of human actions according to the received status of preceding vehicle. By allowing coexistence of the automatic control and driver's actions in a beneficial way, hCCC helps the human driver stabilize the vehicle more efficiently and safely. The proposed hCCC inherits the feedback-feedforward control structure and velocity-dependent spacing policy from the typical CACC systems. String stability analysis shows that hCCC can offer broader string-stable ranges of human parameters than human driving alone or the existing acceleration-based Connected Cruise Control (CCC), indicating a better capability to mitigate traffic disturbance with the uncertain human behaviors. The desirable properties of hCCC were validated in driving simulator experiments, which showed that hCCC could reduce 36.8% acceleration, 31.2% time-gap fluctuation, 81.2% exposure time to unsafe driving situations, and 15.8% fuel consumption from those of human driving alone. In addition, two derivative designs of hCCC are proposed and proven effective, further lowering down the practice threshold of hCCC.
Conference Paper
Electro-Mechanical brakes (EMB) are key tools to improve vehicle safety and performance. However, since the dynamics of the clamping force exhibits a highly nonlinear behaviour, it is typically difficult to tune adequate control laws. In this paper, a model-reference fixed-order controller is proposed, comprising two cascaded gain-scheduled blocks, regulating the motor speed and the pad force, respectively. The corresponding design problem is shown to be nonlinear and non-convex, thus a particle swarm method is employed to find the optimal controller. The advantages of using a nonlinear reference model, as well as its proper selection, are discussed in detail. Numerical results illustrate the effectiveness of the proposed approach on a realistic EMB simulator.
Thesis
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In today’s vehicles, active safety systems are of great importance for both drivers and passengers in the vehicle and for pedestrians. Release to these systems they offer to their customers in various combinations, vehicle manufacturers minimize the occurrence of accidents when they are going to be driven or when they are going to be taken from the station, under the control of the driver or by deactivating the driver. In this study, the hill holder system was designed by using the vehicle dynamics controllers infrastructure. A four-wheel drive vehicle system was created with Matlab Simscape. However, a brake control unit was created with Simulink. Driver inputs are left to the designer by a signal builder and the inclination value to the designer with a constant number block. By establishing a mathematical relationship between the amount of slip on wheels and the vehicle speed, wheel speed, brake pedal position and incline information are the input parameters of the brake control unit. Depending on the slope value in the control unit, the brake pressure and throttle opening values to be transferred according to the conditions in which the hill start assist system is active or deactivated are the output parameters of the control unit. Based on this information, tests have been carried out in cases where the vehicle is active or deactivated according to the pre-designed algorithm in case of a hill.
Article
Control of the electronic non-circular gear brake (ENGB) involves challenges, including the non-linear variation of loads and the effect of friction, which is dependent upon load. The controller must be designed based on modelling information in order to enhance control performance. This study performed model identification of the ENGB system using a DOB-based model identification method. By employing the nearest neighbor search method, the even-odd disturbance was separated without the influence of hysteresis even in situations with low control precision. The accuracy of the resulting ENGB system model was validated through experiments. The self-energizing effect due to friction between the brake disc and pad within the mechanical system was also validated.
Article
This paper proposes an improved autonomous emergency braking (AEB) algorithm intended for intelligent vehicle. Featuring a combination with the estimation of road adhesion coefficient, the proposed approach takes into account the performance of electronic hydraulic brake. In order for the accurate yet fast estimate of road ahead adhesion coefficient, the expectation maximization framework is applied depending on the reflectivity of ground extracted by multiple beams lidar in four major steps, which are the rough extraction of ground points based on 3 σ criterion, the accurate extraction of ground points through principal component analysis (PCA), the main distribution characteristics of ground as extracted using the expectation maximum method (EM) and the estimation of road adhesion coefficient via joint probability. In order to describe the performance of EHB, the response characteristics, as well as the forward and adverse models of both braking pressure and acceleration are obtained. Then, with two typical roads including single homogeneous road and fragment pavement, the safe distance of improved AEB is modeled. To validate the algorithm developed in this paper, various tests have been conducted. According to the test results, the reflectivity of laser point cloud is effective in estimating the road adhesion coefficient. Moreover, considering the performance of EHB system, the improved AEB algorithm is deemed more consistent with the practicalities.
Book
This book presents select proceedings of the International Conference on Future Learning Aspects of Mechanical Engineering (FLAME 2020). The book focuses on latest research in mechanical engineering design and covers topics such as computational mechanics, finite element modeling, computer aided engineering and analysis, fracture mechanics, and vibration. The book brings together different aspects of engineering design and the contents will be useful for researchers and professionals working in this field.
Article
In this paper, a robust sideslip angle controller based on the direct yaw moment control (DYC) is proposed for in-wheel motor electric vehicles. Many studies have demonstrated that the DYC is one of the effective methods to improve vehicle maneuverability and stability. Previous approaches to achieve the DYC used differential braking and active steering system. Not only that, the conventional control systems were commonly dependent on the feedback of the yaw rate. In contrast to the traditional control schemes, however, this paper proposes a novel approach based on sideslip angle feedback without controlling the yaw rate. This is mainly because if the vehicle sideslip angle is controlled properly, the intended sideslip angle helps the vehicle to pass through the corner even at high speed. On the other hand, the vehicle may become unstable because of the too large sideslip caused by unexpected yaw disturbances and model uncertainties of time-varying parameters. From this aspect, disturbance observer (DOB) is employed to assure robust performance of the controller. The proposed controller was realized in CarSim model described actual electric vehicle and verified through computer simulations.
Article
Brake-by-wire (BBW) system is an important safe component of intelligent vehicles. The fast and stable current control of permanent magnet synchronous motor (PMSM) is a key factor that ensures the dynamic response performance of BBW. Hence, a fusion predictive control (FPC) method based on uncertain algorithm is proposed, which solves the parameter sensitivity problem in traditional deadbeat current control of PMSM. It contains a fusion predictive controller, a flux observer and an uncertain controller. The FPC integrates forward linear prediction (FLP) and deadbeat prediction (DP) to improve the current response speed. Considering the model parameter mismatch of the controller, the uncertain controller can adjust the reliability of FLP and DP in the FPC in real time through the uncertainty measurement. On the basis of the whole system, a flux observer is designed, which can dynamically adjust the parameters of flux to satisfy the current loop. Both simulation and experimental results show that this method reduces the sensitivity of system parameters and improves the dynamic performance of the current loop (up to 12.56%).
Article
A novel compact initiative braking system orienting intelligent vehicles and autonomous driving is revealed. The delicate arrangement of on-off switch valves guarantees precise hydraulic pressure modulation. Integrated stroke simulator provides a well-tuned pedal force feedback. The fallback level is intensively designed to be non-degraded. A hierarchical control frame with the underlying hydraulic controller is designed to govern operation procedures. The underlying hydraulic controller is set up based on adaptive gain scheduling PD controller and Logic Threshold control. Hardware-In-Loop tests are carried out in full perspectives. The test result of slope-sine combination tracking shows that, compared with the conventional PID controller, the designed underlying controller achieves higher pressure modulation accuracy with no chattering effect. Controller robustness to accumulator pressure fluctuation is proven by dual-cylinder tracking test. A batch of step-response tests under different accumulator pressures shows a rapid pressure building capability in emergency situations under all pressure range. The fail-safe test result indicates that conventional hydraulic brake can be restored in 1.5s with the operation of the driver, which significantly increases the margin of brake safety for highly autonomous vehicles. The regenerative braking test result suggests the immense potential of the developed system in application to electrified vehicles.
Conference Paper
X-by-wire (XBW) technologies lay the foundation for electric and autonomous vehicles, and one of the most important aspects is the brake-by-wire (BBW) systems, among which, the electro-hydraulic brake (EHB) has already been applied to commercial vehicles successfully. To satisfy the demands for fast response and high reliability of the BBW system, a novel electric booster (E-Booster) combined with EHB is designed in this paper actuated by a BLDC motor. By careful analysis, a detailed model of the EHB system with E-Booster is established. As precise pressure control is crucial for the performance of EHB system, a dual-loop adaptive control algorithm is proposed which could attenuate external disturbances even with unknown system parameters. Finally, simulation results prove the effectiveness of the proposed control method. Moreover, this control scheme has the potential to be integrated into advanced applications, such as active vehicle dynamics control of intelligent and autonomous vehicles.
Conference Paper
Full-text available
Yaw stability of an automotive vehicle in a steering maneuver is critical to the overall safety of the vehicle. In this paper we present a theoretical development and experimental results of a vehicle yaw stability control system based on generalized predictive control (GPC) method., The controller tries to predict the future yaw rate of the vehicle and then takes control action at present time based on future yaw rate error. The proposed controller utilizes the insight into the yaw rate error growth when the automobile is in an understeer or oversteer condition on a low friction coefficient surface in a handling maneuver. Experimental results show that the predictive feature of the proposed controller provides an effective way to control the yaw stability of a vehicle.
Conference Paper
Full-text available
Emerging drivetrains open new possibilities in vehicle stability control. In this paper, we consider a vehicle powered by four independently driven wheel motors, one for each wheel, with steer-by-wire. We explore the possibilities of using steering and individual wheel acceleration on top of braking to enhance stability and steerability. A 7-DOF model is developed to capture the vehicle longitudinal, lateral and yaw motion and the other four degrees of motion representing the wheel dynamics. However, this 7-DOF model is rather complicated for controller design due to the coupling of the inputs, and because the tire forces are highly nonlinear and coupled when the tires are at their limits. A control oriented model is developed that decouples the inputs and facilitates ease in control algorithm development. In addition, the longitudinal and lateral forces are also decoupled based on detailed analysis of the tire behavior at their limits. Simulation results of both the 7-DOF model and the control oriented model are compared to show that the control oriented model is capable of capturing the vehicle behavior at safety-critical cases.
Conference Paper
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This work presents a nonlinear sliding mode type controller for slip regulation in a braking event for a hybrid electromagnetic-electrohydraulic brake-by-wire system. The ABS controller modifies the brake torque command generated by a supervisory controller based on driver's command via brake pedal sensor. The brake torque command is then generated by closed loop actuator control algorithm to control the eddy current brake (ECB) and electrohydraulic brake (EHB) systems. The proposed control algorithm shows very good slip regulation in a braking event on low friction coefficient surfaces when compared with non-ABS braking. Usage of ECB resulted in a smooth ABS stop minimizing the NVH of current hydraulic ABS systems.
Conference Paper
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This paper presents a novel analytical redundancy technique for fault diagnostics of a differential brake control system. The proposed diagnostic algorithm builds upon open loop and closed loop state estimators to generate residuals and identify failures. By judiciously utilizing the residual information, it is possible to detect faults at the component level rather than at the system level. In addition, robust and adaptive estimators are shown to effectively combat with two perennial nuisances of fault diagnostic algorithms: sensitivity to disturbance and false alarms. Hardware-in-the-loop simulation studies show how reliably the proposed diagnostic algorithm detects faults in the differential brake control system that is expected to play a crucial role in active vehicle safety.
Conference Paper
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This paper describes the preliminary research and implementation of an experimental test bench set up for an electric vehicle antilock braking system (ABS)/traction control system (TCS) representing the dry, wet and icy road surfaces. A fuzzy logic based controller to control the wheel slip for electric vehicle antilock braking system is presented. The test facility comprised of an induction machine load operating in the generating region. The test facility was used to simulate a variety of tire/road μ-σ driving conditions, eliminating the initial requirement for skid-pan trials when developing algorithms. Simulation studies and results are provided.
Conference Paper
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This paper presents an experimental evaluation of a brake-by-wire application that tolerates transient faults by temporal error masking. A specially designed real-time kernel that masks errors by triple time-redundant execution and voting executes the application on a fail-stop computer node. The objective is to reduce the number of node failures by masking errors at the computer node level. The real-time kernel always executes the application twice to detect errors, and ensures that a fail-stop failure occurs if there is not enough CPU-time available for a third execution and voting. Fault injection experiments show that temporal error masking reduced the number of fail-stop failures by 42% compared to executing the brake-by-wire task without time redundancy.
Conference Paper
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This paper examines the usefulness of a brake steer system (BSS) which uses differential brake forces for steering intervention in the context of intelligent vehicle highway systems. The resulting moment on the vehicle affects yaw rate and lateral position, thereby providing a limited steering function. The steering function achieved through BSS can then be used to control lateral position in an unintended road departure system. Models for the vehicle and the brake system are presented. A state feedback regulator and PID controller are developed to explore BSS feasibility and capability. Computer simulation results are included
Article
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In this article, a new multistep ahead predictive filtering scheme is introduced. The proposed technique is essential for proper operation of safety-critical components in a drive-by-wire car. Because limited computational time and memory are available in drive-by-wire systems, the main advantage of our scheme is that it only requires one set of finite impulse response (FIR) filter weights to be tuned while it can be used for different numbers of steps ahead predictions. To verify and compare the proposed filter, our model and four competing methods were applied to predict up to four missing samples of displacement sensor data from a brake pedal in a brake-by-wire system. Experimental results show that prediction performance of our proposed FIR filter is higher than, or at least comparable to, other filters with the same memory requirements and the computational overhead of data missing handling by our proposed method is considerably lower than other comparable methods. Hence, the proposed filter has a superior performance in missing data compensation for drive-by-wire systems.
Article
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The application of fuzzy-based control strategies has gained enormous recognition as an approach for the rapid development of effective controllers for nonlinear time-variant systems. This paper describes the preliminary research and implementation of a fuzzy logic based controller to control the wheel slip for electric vehicle antilock braking systems (ABSs). As the dynamics of the braking systems are highly nonlinear and time variant, fuzzy control offers potential as an important tool for development of robust traction control. Simulation studies are employed to derive an initial rule base that is then tested on an experimental test facility representing the dynamics of a braking system. The test facility is composed of an induction machine load operating in the generating region. It is shown that the torque-slip characteristics of an induction motor provides a convenient platform for simulating a variety of tire/road μ-σ driving conditions, negating the initial requirement for skid-pan trials when developing algorithms. The fuzzy membership functions were subsequently refined by analysis of the data acquired from the test facility while simulating operation at a high coefficient of friction. The robustness of the fuzzy-logic slip regulator is further tested by applying the resulting controller over a wide range of operating conditions. The results indicate that ABS/traction control may substantially improve longitudinal performance and offer significant potential for optimal control of driven wheels, especially under icy conditions where classical ABS/traction control schemes are constrained to operate very conservatively.
Conference Paper
This paper presents a novel analytical redundancy technique for fault diagnostics of a differential brake control system. The proposed diagnostic algorithm builds upon open loop and closed loop state estimators to generate residuals and identify failures. By judiciously utilizing the residual information, it is possible to detect faults at the component level rather than at the system level. In addition, robust and adaptive estimators are shown to effectively combat with two perennial nuisances of fault diagnostic algorithms: sensitivity to disturbance and false alarms. Hardware-in-the-loop simulation studies show how reliably the proposed diagnostic algorithm detects faults in the differential brake control system that is expected to play a crucial role in active vehicle safety.
Article
By-wire systems have been established for several years in the area of aircraft constructions. There is the visible trend to realize by-wire applications without mechanical or hydraulic backup systems in vehicles. The required electronic systems must evidently be available and safe. This paper addresses a new automotive architecture approach using the time-triggered fault-tolerant TTP protocol that has been designed for class C safety related control applications, like brake-by-wire or steer-by-wire, due to the SAE classification [1]. As an example we present this approach within a brake-by-wire research car (case study) without mechanical backup. The intention of this architecture is to tolerate one arbitrary fault -excepting faults of actuators -without any effects of the brake performance. For this purpose we use redundancy in communication (TTP) and electric components like sensors, actuators and power supply.
Conference Paper
The paper presents the control design for antilock braking systems via the sliding mode approach. In this study we formulate the problem as that of extremum searching in a highly uncertain situation. We consider the friction force as an output of the dynamic system which includes mechanical motion equations and the hydraulic circuit equations. This setting is complicated by the optimized function being a priori unknown, and the input (slip) not being measurable
Conference Paper
In this paper we describe the development and verification of software for an automotive brake-by-wire system. This is a new brake system without mechanical or hydraulic backup. The system is based on a time-triggered communication architecture. The central control computer in this distributed system, called Brake-by-Wire Manager, is a redundant design in order to tolerate any single failure. The software of this computer is subject to a set of safety related requirements which must be verified. We have developed the software using synchronous software components based on the synchronous ESTEREL. Many safety properties have been verified successfully and the software has been integrated in a prototype brake-by-wire system in a research car
Article
The antilock braking systems are designed to maximize wheel traction by preventing the wheels from locking during braking, while also maintaining adequate vehicle steerability; however, the performance is often degraded under harsh road conditions. In this paper, a hybrid control system with a recurrent neural network (RNN) observer is developed for antilock braking systems. This hybrid control system is comprised of an ideal controller and a compensation controller. The ideal controller, containing an RNN uncertainty observer, is the principal controller; and the compensation controller is a compensator for the difference between the system uncertainty and the estimated uncertainty. Since for dynamic response the RNN has capabilities superior to the feedforward NN, it is utilized for the uncertainty observer. The Taylor linearization technique is employed to increase the learning ability of the RNN. In addition, the on-line parameter adaptation laws are derived based on a Lyapunov function, so the stability of the system can be guaranteed. Simulations are performed to demonstrate the effectiveness of the proposed NN hybrid control system for antilock braking control under various road conditions.
Conference Paper
A d.c.-motor-based brake-by-wire system is studied for the purpose of fault diagnostics of the power electronic switches. The voltage and current generated in the switching circuit under normal and six faulted conditions are observed. A hierarchical fuzzy diagnostic system has been developed to detect certain types of fault condition in any specific solid state power switch at the moment immediately after the occurrence of the fault. The hierarchical fuzzy diagnostic system has been tested and validated using data from both a simulation and a laboratory set-up with a 1/3 hp d.c. motor and a d.c.-to-d.c. converter. The system performance has been compared with two different fuzzy diagnostic systems and the results are presented. The hierarchical fuzzy diagnostic system trained on the simulated model has the capability of detecting certain types of fault condition occurring in a brake-by-wire actuator system set-up in a laboratory in less than 0.0009 s and pinpointing the specific types of fault within less than 0.013 s.
Conference Paper
In this paper, a vision-based lane-keeping automated steering system is proposed and is successfully verified in our vehicle platform, TAIWAN iTS-1. The proposed steering system can achieve the accurate detection of the complicated road environment information; and more, the closed-loop automated lane-keeping steering system with virtual look-ahead is stable under varying speed operation. Furthermore, to achieve more manlike driving behavior such as smooth tuning, a fuzzy gain schedule technology is proposed to concern with lateral offset and instant-speed of the vehicle, and hence, to compensate the feedback controller for adapting to the steering wheel command appropriately. The proposed steering system is demonstrated via TAIWAN iTS-1 on the standard testing road in automotive research and testing center (ARTC) and highway road.
Conference Paper
Brake-by-wire means that the direct mechanical link between brake pedal and braking cylinder is completely replaced by an electromechanical braking system. This concept, originally used for aircraft and military only, has massive advantages for implementing in new car designs. As a consequence, the pedal movement can be generated arbitrarily. Ideally, the pedal could behave like a conventional brake. In the paper, a simplified model for the desired dynamical behavior of the pedal unit is presented, which can be tuned for specific requirements like pedal force, and pedal movement. Its numerical solution leads, due to the pedal force, to the desired time-indexed trajectory of the pedal. Secondly, there is presented a closed loop control strategy for a hydraulic driven pedal consisting of an electric pump, servo valve and a differential cylinder in order to track the reference trajectory. Experimental results show the efficiency of the presented controller for the movement of brake pedals in brake-by-wire car design concepts as pedal simulator.
Conference Paper
A new model for four wheel driving (4WD) vehicles and a fuzzy control system that enhances vehicle yaw stability especially in fast evasive maneuvers performed to the safety limit are developed. The driver handles the front steering angle over a turn, while the controller commands the braking forces of individual wheels and rear steering effort. This mitigates the vehicle's oversteer or understeer tendencies during emergent cornering situation. The fuzzy controller is firstly established by qualitative analysis of the dynamics of the vehicle and tires. The available control authority and effect are then evaluated by implementing the controller on the 4WD vehicle model developed before using computer simulation. The simulation results demonstrate the benefit of the proposed control method in terms of improved vehicle response. Specifically, the method is practical for it is simpleness and robustness.
Conference Paper
In this paper, we propose a robust sliding mode-like fuzzy logic controller for an anti-lock brake system (ABS) with self-tuning of the dead-zone parameters. The main control strategy is to force the wheel slip ratio tracking the optimum value 0.2. The proposed controller for anti-lock braking systems provides a stable and reliable performance under the uncertainties in vehicle brake systems. Simulation results will show the validity and effectiveness of the proposed sliding mode-like fuzzy logic controller.
Conference Paper
In this paper, an output feedback direct adaptive fuzzy neural controller for an anti-lock braking system (ABS) is developed. It is assumed that only the system output and the wheel slip ratio, is available for measurement. The main control strategy is to force the wheel slip ratio tracking variant optimal slip ratios, which may vary with the environment and assumed to be known during the vehicle-stopping period. By using the strictly-positive-real (SPR) Lyapunov theory, the stability of the closed-loop system can be verified. To demonstrate the effectiveness of the proposed method, simulation results are illustrated.
Conference Paper
The antilock braking systems are designed to maximize wheel traction by preventing the wheels from locking during braking, while also maintaining adequate vehicle steerability; however, the performance is often degraded under harsh road conditions. In this study, a robust hybrid control system is developed for the antilock braking systems. In this design method, the robust hybrid control system is comprised of a hybrid controller and a robust controller to achieve a desired H<sup>∞</sup> control performance. The hybrid controller containing a fuzzy uncertainty observer is the principal controller, and the robust controller is designed to achieve the desired H<sup>∞</sup> tracking performance. Finally, simulations are performed to demonstrate the effectiveness of the proposed robust hybrid control system for antilock braking control under various road conditions.
Conference Paper
A discrete-time adaptive fuzzy sliding mode controller is proposed for an antilock braking system (ABS) of a 13th order two-wheel nonlinear model of a car. The model includes interaction of front and rear wheel subsystems. The presented controller aims to least depend on a mathematical model, only assuming certain upper and lower bounds of uncertainties. The controller is designed based on a hybrid combination of variable structure control, direct adaptive fuzzy control and linear control. Two fuzzy approximators are used to estimate nonlinear functions of the plant. The controller is global uniform Lyapunov stable. Simulation results show favorable output tracking performance despite poor knowledge of wheel dynamics and system disturbances such as road roughness.
Conference Paper
Yaw stability control systems are important components of active safety systems for road transport. A model regulator based yaw stability control system that was previously implemented and tested very successfully as a steering controller is adapted to work as an individual wheel braking controller in this paper. A two track nonlinear vehicle model is used to test the individual wheel braking actuated model regulator developed here. Simulation results are used to demonstrate the achievement of good yaw disturbance moment rejection by the proposed controller.
Conference Paper
Active safety of road transport requires, among other things, the improvement of road vehicle yaw stability by active control. One approach for yaw dynamics improvement is to use differential braking, thereby creating the moment that is necessary to counteract the undesired yaw motion. An alternative approach is to command additional steering angles to create the counteracting moment. The maximum benefit, of course, can be gained through coordinated and combined use of both methods of corrective yaw motion generation in a control strategy. This problem has been approached by using a revised model regulator here as the main controller that utilizes coordinated steering and individual wheel braking actuation, with the aim of achieving better vehicle yaw stability control. Independent use of the individual means of actuation are treated first. Possible strategies for combined and coordinated use of steering and individual wheel braking action in a vehicle yaw dynamics controller are then presented. Simulation results on a nonlinear two track vehicle model are used to illustrate the effectiveness of the coordinated approach.
Conference Paper
A recent trend in the automotive industry is the introduction of 'x-by-wire' technologies, for example steer- and brake-by-wire, in order to replace purely mechanical systems with electromechanical ones. Clearly, such systems have to operate safely under any circumstances in order to not endanger the passengers and the environment of x-by-wire equipped vehicles. To be able to measure qualitative aspects of x-by-wire systems at the abstract level of architecture, this article introduces a class of timed Petri-Nets which allows for the modeling and simulation of such systems. With the help of a brake-by-wire example, it is shown how aspects like robustness and fault-tolerance can be measured.
Conference Paper
An adaptive discrete time fuzzy sliding mode controller is proposed for an anti-lock braking system (ABS). Due to strong uncertainties in car/brake environment, the presented controller aims to least depend on a mathematical model. The controller is designed based on a hybrid combination of variable structure control, direct adaptive fuzzy control and linear control. Two fuzzy approximators are used to estimate nonlinear functions of the plant. The sliding mode controller guarantees that states remain within a valid approximation region, hence obtaining globally and uniformly Lyapunov stability. Simulation results show that the approach gave good output tracking performance despite road uncertainties and disturbances.
Conference Paper
The paper outlines simulation studies and investigations of a hydraulic actuated brake (HAB) and an alternative electromechanically actuated brake (EMB) system on a half-car model using the Simulink environment. The vehicle simulation model used is briefly explained as follows. Both implementations build on a brake by wire technology, which is essentially an interface for driver assistance. The input is obtained from 0-100% brake actuation converted into pressure applied to the brake system. This gives scope for further development, for example increasing brake pressure in emergency situations and traction control. Additionally, it covers safety aspects in design and implementation. For example, a design for a hydraulic based brake-by-wire pedal emulator with failed power braking requirements may be found in Zehnder et al. (1999). In the paper various ABS control strategies utilizing HAB and EMB technologies are evaluated and compared. The ABS control strategies are outlined and comparisons of the results are discussed
Conference Paper
Electronic controls have been developed to improve vehicle dynamics in automotive applications. Several luxury vehicle manufacturers have positioned themselves to offer increased vehicle stability by expanding the current anti-lock brake system (ABS) and traction control system (TCS) technology into the arena of yaw control. A yaw control algorithm is developed to give an additional measure of vehicle stability control during adverse driving maneuvers over a variety of road conditions. By measurements of vehicle states, the control algorithm determines the level of vehicle stability and intervenes as necessary through individual wheel braking to provide added stability and handling predictability. The control law is based on optimum search for minimum yaw rate via sliding mode control
Conference Paper
Presents coprime factors speed scheduling of H<sub>∞</sub> controllers for vehicle lateral control. The methodology uses the state feedback-observer form of the controller for robust interpolation. The synthesized controllers are tested for several driving maneuvers at different speeds and road conditions
Conference Paper
Although ABS has been widely spread on the commercial market for twenty years, throughgoing investigations with rigorous theoretical background have been lacking in the automotive literature. The control strategies of commercial ABS are mostly based on table rules to be calibrated through various experiments and tests, and the system dynamics cannot be effectively considered in the controller design. Due to the challenges in the automobile industry it is desired to develop a technique which still enhances the control performance and robustness with respect to various vehicle types and environment conditions. Motivated by these goals, a robust adaptive control algorithm is developed in this work. The proof of asymptotic stability is based on the Lyapunov method. The objective of such control is to maximize the tire friction under the assumption of knowing the optimal value of target slip. It is shown that, without any prior knowledge of the tire force and system parameters, the slip error is bound to converge to zero asymptotically. The robustness of the control system with respect to variation of the system parameters is guaranteed. The brake dynamic system to be controlled includes mechanical motion equations and the hydraulic circuit equations. A two-level control scheme is applied for the controller design, which considers the both parts separately
Conference Paper
The problem of the wheel torque control for independent rear wheel drive vehicle is considered. This problem is especially relevant in a view of the modern trends to integrating the antilock braking systems (ABS) and antislip control systems (ACS) in the car. The plant model is presented by fifth order differential system including three degree of freedom single mass flat model of the car and second order model of wheel dynamics. It is shown by simple considerations that order of the plant can be reduced to the second one. The single track vehicle model is shown to be used not only at a constant riding speed but at the high velocities with limited variations as well. The reference inputs are defined for torque controlled vehicle to be like four wheel steering (FWS) one with high maneuverability at a low speed and high stability at a high speed. So FWS system is discussed to be redundant in the car with ABS and ACS. The sliding mode technique is applied for control design. Naturality of the use of sliding modes is caused by discontinuous mode of the actuators of ABS (ACS). A comparison between controlled and conventional cars is provided by computer simulations under various driving conditions such as lateral disturbance, lane change, turn at a low speed and variations of mass distribution
Article
A typical antilock brake system (ABS) senses when the wheel lockup is to occur, releases the brakes momentarily, and then reapplies the brakes when the wheel spins up again. In this paper, a genetic neural fuzzy ABS controller is proposed that consists of a nonderivative neural optimizer and fuzzy-logic components (FLCs). The nonderivative optimizer finds the optimal wheel slips that maximize the road adhesion coefficient. The optimal wheel slips are for the front and rear wheels. The inputs to the FLC are the optimal wheel slips obtained by the nonderivative optimizer. The fuzzy components then compute brake torques that force the actual wheel slips to track the optimal wheel slips; these torques minimize the vehicle stopping distance. The FLCs are tuned using a genetic algorithm. The performance of the proposed controller is compared with the case when maximal brake torques are applied causing a wheel lockup, and with the case when wheel slips are kept constant while the road surface changes
Article
There exist several problems in the control of brake systems including the development of control logic for antilock braking systems (ABS) and “base-braking.” Here, we study the base-braking control problem where we seek to develop a controller that can ensure that the braking torque commanded by the driver will be achieved. In particular, we develop a fuzzy model reference learning controller, a genetic model reference adaptive controller, and a general genetic adaptive controller, and investigate their ability to reduce the effects of variations in the process due to temperature. The results are compared to those found in previous research
Article
This paper addresses the modeling and control of the lateral motion of a highway vehicle. In particular, a steering controller is designed that tracks the center of the present lane on both curved and straight highway sections without knowledge of the radius of curvature of the road. Also, it is shown that a lane change maneuver can be completed on a curved road section using this controller. The controller is designed using an H<sub>∞</sub>-based loop shaping design procedure due to McFarlane and Glover. It is shown that this controller achieves the required performance as well as exhibiting excellent robustness. In particular, the controller's robustness due to varying speeds, icy road conditions, and wind gusts are examined
Article
The paper presents the control design for antilock braking systems via the sliding mode approach. In this study the authors formulate the problem as that of extremum searching in a highly uncertain situation. The authors consider the friction force as an output of the dynamic system which includes mechanical motion equations and the hydraulic circuit equations. This setting is complicated by the optimized function being a priori unknown, and the input (slip) not being measurable
Article
The article begins with a review of electronic driver assisting systems such as ABS, traction control, electronic stability control, and brake assistant. We then review drive-by-wire systems with and without mechanical backup. Drive-by-wire systems consist of an operating unit with an electrical output, haptic feedback to the driver, bus systems, microcomputers, power electronics, and electrical actuators. For their design safety, integrity methods such as reliability, fault tree and hazard analysis, and risk classification are required. Different fault-tolerance principles with various forms of redundancy are considered, resulting in fail-operational, fail-silent, and fail-safe systems. Fault-detection methods are discussed for use in low-cost components, followed by a review of principles for fault-tolerant design of sensors, actuators, and communication. We evaluate these methods and principles and show how they can be applied to low-cost automotive components and drive-by-wire systems. A brake-by-wire system with electronic pedal and electric brakes is then considered in more detail, showing the design of the components and the overall architecture. Finally, we present conclusions and an outlook for further development of drive-by-wire systems.
Article
Hybrid electric vehicles (HEVs) use multiple sources of power for propulsion which provides great ease and flexibility to achieve advanced controllability and additional driving performance. In this paper, the electric motor in HEV and electric vehicle (EV) propulsion systems is used to achieve antilock braking performance without a conventional antilock braking system (ABS). The paper illustrates that the antilock braking of HEV can be easily achieved using iterative learning control for various road conditions. A vehicle model, a slip ratio model, and a vehicle speed observer were developed to control the antilock performance of HEV during braking. Through iterative learning process, the motor torque is optimized to keep the tire slip ratio corresponding to the peak traction coefficient during braking. Simulations were performed on a compact size vehicle to validate the proposed control method. The control algorithm proposed in this paper may also be used for the ABS control of conventional vehicles.