Mats Jonasson

Chalmers University of Technology · Department of mechanics and maritime sciences

This paper aims to maximize deceleration on split friction roads by combining steering and individual wheel braking. For this, a previously tested optimization problem is adapted to curved roads. The optimal brake force and steering allocation is investigated as a function of the split friction asymmetry. Results show that low friction is more detr...

Articulated heavy vehicles (AHVs) face yaw instabilities, especially under extensive propulsion or regenerative braking force on the driven axles, risking their directional stability and potentially leading to jackknifing. Hence, safe operating envelopes (SOEs) are essential for allocating propulsion and braking forces among different units. This s...

This paper studies the optimization of ride comfort during the maneuver of bus docking at a stop station. We propose an analytical comfort model that considers the coupled and nonlinear effect of acceleration and jerk levels on the comfort perceived by standing bus passengers. This is studied through offline path planning by formulating the docking...

Articulated Heavy Vehicles (AHVs) play a crucial role in today’s transportation, offering significant commercial and environmental advantages. However, challenges like jackknifing and trailer swing in AHVs highlight the need for focused research. This paper introduces innovative yaw stability algorithms designed to tackle these concerns, employing...

The electrification of towing and trailing units creates new torque allocation alternatives among different units of articulated heavy vehicles. To increase the power and energy efficiency, control algorithms can request propulsion or regenerative braking from a single unit while keeping the other units unbraked or unpropelled. However, this may le...

The electrification of commercial vehicles has led to new wheel torque allocation options for propulsion and braking of articulated heavy vehicles. Each unit or axle can be individually braked or propelled whilst the other units or axles are excluded from such action. This may achieve the best energy efficiency. However, this can also lead to poten...

As articulated heavy vehicles switch to electric power, new ways of allocating wheel forces have emerged. To improve energy efficiency, it is increasingly common to use propulsion or regenerative braking on only one unit of the vehicle combination. This leads to yaw stability problems, mainly jackknifing if the towing unit has excessive wheel force...

This paper shows how a safe operating envelope based on simulated data can be implemented in an allocation-type control system for a two-unit heavy vehicle. The vehicle in focus is a tractor semi-trailer combination for which firstly safe driving conditions are defined and then control laws and systems are designed with respect to set safe driving...

This paper investigates the remaining fluctuation of road friction and stopping distance when the contribution from known sources has been removed. This fluctuation can serve as uncertainty for active safety functions relying on friction estimates. Data from repeated ABS brake maneuvers on several uniform road conditions, including high and low fri...

The objective of this paper is to explore the potential of combining hardware and software design parameters in the optimization for reduced energy consumption in an electric vehicle. The vehicle used has four electric motors connected to one wheel each through a single speed transmission and a controllable coupling. The software design parameter c...

Electrification of commercial heavy vehicles has led to the offer of different electric drive-based powertrain architectures, most of them with the adaptation of the diesel engine based architecture. Due to the limited driving range possible, optimal configuration of the powertrain becomes a vital task with the battery as the energy source, which a...

As vehicles become increasingly electrified, electrical machines for propulsion can be divided into many sources making the vehicle highly over-actuated. For over-actuated vehicles, the allocation of a propulsive force is an underdetermined process with respect to both the number of wheels and electrical machines. Hence, the allocation can be made...

This work considers the problem of position and position-uncertainty estimation for autonomous vehicles during power black-out, where it cannot be assumed that any position data is accessible. To tackle this problem, the position estimation will instead be performed using power separated and independent measurement devices, including one inertial 6...

The present paper provides a thorough analysis and reveals the yaw torque generated by tyre lateral forces, due to the well-known combined slip effect. The indirect yaw torque here is captured by a tyre model simplification designed for the real-time control allocation purpose. Experiments were carried out by a driving robot, controlling steering w...

In the present paper, an Evasive Manoeuvre Assist (EMA) function is designed to adapt to different types of drivers, by an optimised steering torque overlay. The existing EMA function amplifies the driver steering inputs using a feed-forward controller which might not necessarily help an over-reactive driver. There exists a need for an EMA which ad...

In this paper we describe how vehicle systems and the vehicle motion control are affected by automated driving on public roads. We describe the redundancy needed for a road vehicle to meet certain safety goals. The concept of system safety as well as system solutions to fault tolerant actuation of steering and braking and the associated fault toler...

This work deals with utilisation of active steering and propulsion on individual wheels in order to improve a vehicle's energy efficiency during a double lane change manoeuvre at moderate speeds. Through numerical optimisation, solutions have been found for how wheel steering angles and propulsion torques should be used in order to minimise the ene...

In recent work, an autonomous collision avoidance system was described, targeting combined speed and path changes based on optimal control theory. Similar to other motion control problems dominated by friction limits at the tyres, an optimal particle motion is used as the control reference. The scenario is a potential frontal crash with another veh...

In the present paper, a real-time integrated Torque Vectoring Control function is designed and implemented in an AWD axle-split hybrid vehicle. The front axle has a conventional combustion engine, and two individually controlled electric motors are located at the rear axle. The function aims to enhance the vehicle cornering performance by yaw torqu...

How to use machine learning to estimate and predict road friction

Actively controlling the camber angle to improve energy efficiency has recently gained interest due to the importance of reducing energy consumption and the driveline electrification trend that makes cost-efficient implementation of actuators possible. To analyse how much energy that can be saved with camber control, the effect of changing the camb...

Actively controlling the camber angle to improve energy efficiency has recently gained interest due to the importance of reducing energy consumption and the driveline electrification trend that makes cost-efficient implementation of actuators possible. To analyse how much energy that can be saved with camber control, the effect of changeing the cam...

This paper describes how differential braking can be used to turn a vehicle in the context of providing fail-operational control for self-driving vehicles. Two vehicle models are developed with differential input. The models are used to explain the bounds of curvature that differential braking provides and they are then validated with measurements...

The new capabilities of autonomous cars can be used to mitigate to a large extent safety concerns and nuisance traditionally associated with double parking. In this paper double parking for autonomous cars is proposed as a new approach to temporarily increase parking capacity in locations in clear need for extra provision when best alternatives can...

This paper investigates how model predictive control can be used to control the acceleration of an over actuated vehicle equipped with a combustion engine and friction brakes. The control problem of keeping appropriate comfort and low energy consumption and simultaneously follow an acceleration reference is described. Vehicle and actuator models ar...

More accurate information about the basic vehicle parameters can improve the dynamic control functions of a vehicle. Methods for online estimation of the mass, the rolling resistance, the aerodynamic drag coefficient, the yaw inertia and the longitudinal position of the centre of gravity of an electric hybrid vehicle is therefore proposed. The esti...

This paper evaluates the effectiveness of an active chassis control function after an initial light impact. The experiment was designed in a high-fidelity driving simulator with motion platform that is adapted to mimic a real-world crash. The post-impact control function here superimposes individual-wheel brake and steering wheel torque in order to...

Knowledge of the maximum tyre-road friction coefficient can improve active safety systems by defining actuator boundaries and adaptable intervention thresholds. Estimation of the coefficient of friction based on tyre response measurements requires large level of force excitation. Under normal driving conditions, manoeuvres with large tyre utilizati...

This work deals with how to utilise active suspension on individual vehicle wheels in order to improve the vehicle performance during straight-line braking. Through numerical optimisation, solutions have been found as regards how active suspension should be controlled and coordinated with friction brakes to shorten the braking distance. The results...

Three fault-tolerant control strategies for electric vehicles with wheel hub motors are presented and compared, which are all based on the control allocation principle. The main objective is to maintain the directional stability of the vehicle in case of a component failure during high speed manoeuvres. Two simplified strategies that are suited for...

This paper investigates the optimal control of a vehicle, after a light impact during a traffic accident. To reduce the risk of secondary events, the control target is set: to minimize the maximum lateral deviation from the initial path. In previous analysis path control was achieved by the active control of individual wheel braking. The present pa...

This paper presents a research study on the optimal way to negotiate safety-critical vehicle manoeuvres depending on the available actuators and road friction level. The motive is to provide viable knowledge of the limitations of vehicle capability under the presence of environmental preview sensors. In this paper, an optimal path is found by optim...

This paper presents a vehicle path controller for reducing the maximum lateral deviation (Y<sub align="right"> max </sub>) after an initial impact in a traffic accident. In previous research, a Quasi-Linear Optimal Controller (QLOC) was proposed and applied to a simple vehicle model with individually controlled brake actuators. QLOC uses non-linear...

This paper considers the problem of path control for a road vehicle immediately after it is disturbed by an initial light collision. Assuming that the driver cannot adequately control the vehicle during such an event, active chassis controls such as front steering and friction brakes are applied to minimize the risk and/or severity of a secondary i...

This paper investigates brake-based path control of a passenger vehicle, aimed at reducing secondary collision risk, following an initial impact in a traffic accident. This risk may be reduced if lateral deviations from the preimpact path can be minimized, at least on straight roads. Numerical optimization has previously shown that coupled control...

This paper compares instantaneous tyre force allocation with trajectory optimization for a vehicle equipped with individual propulsion and braking. The distribution process of vehicle forces to the actuators is evaluated for both methods. The evaluation is done for a limit handling manoeuvre, and therefore, particular interest is paid on how actuat...

This paper presents a fault handling strategy for electric vehicles with in-wheel motors. The applied control algorithm is based on tyre-force allocation. One complex tyre-force allocation method, which requires non-linear optimization, as well as a simpler tyre force allocation method are developed and applied. A comparison between them is conduct...

This paper investigates brake-based path control of a passenger vehicle, aimed at reducing secondary collision risk following an initial impact in a traffic accident. Previous results from numerical optimisation showed that, at varying severity levels of post-impact states, there exist three identifiable components within the optimal control strate...

This paper considers brake-based lateral control of a passenger vehicle, for reducing secondary collision risk following an initial impact in a traffic accident. Since secondary collisions are associated with deviations from the original travel path, the control problem is formulated via brake control sequences that minimize lateral path deviation....

The capability of over-actuated vehicles to maintain stability during limit handling is studied in this paper. A number of important differently actuated vehicles, equipped with hydraulic brakes toward more advanced chassis solutions, are presented. A virtual evaluation environment has specifically been developed to cover the complex interaction be...

This paper formulates force constraints of over-actuated road vehicles. In particular, focus is put on different vehicle configurations provided with electrical drivelines. It is demonstrated that a number of vehicles possesses non-convex tyre and actuator constraints, which have an impact on the way in which the actuators are to be used. By mappin...

Dymola and Modelica have been used in research at KTH Vehicle Dynamics since 2000. With the intro-duction of new templates and standard components, Modelica has become increasingly accessible for researchers and students in the field of vehicle dy-namics and therefore a project was initiated to evalu-ate its usefulness as an educational tool. The g...

In this paper, model predictive control (MPC) is applied for controlling an over‐actuated vehicle. The control problem is associated with the distribution of the tyre forces to ensure vehicle stability. The use of MPC is shown to be a suitable method if the vehicle's future desired trajectory is known. Simulation studies conducted show that access...

This paper presents a general force allocation strategy for over-actuated vehicles, utilising technologies where tyre forces can be more freely controlled than in conventional vehicles. For the purpose of illustration, this strategy has been applied and evaluated using a design proposal of an autonomous corner module (ACM) chassis during a transien...

This paper presents an electromechanical wheel suspension, where the upper arm of the suspension has been provided with an electric levelling and a damper actuator, both are allowed to work in a fully active mode. A control structure for the proposed suspension is described. The complex design task involving the control of the electric damper and i...

This paper describes how a vehicle model from the VehicleDynamics Library is configured, parameterised and validated for predicting limit handling manoeu-vres. Particular attention is paid to the selection of sub-system models with suitable levels of detail, as well as the selection of measurements performed and measur-ing equipment. A strong princ...

In this paper, vehicle dynamics for electric vehicles equipped with in-wheel motors and individual steering actuators are studied adopting the principles of optimal tyre-force allocation. A simple method for describing the constraints owing to tyre and actuator limitations is described. The control architecture is evaluated by investigating its res...

This paper presents an analysis of the stability of an electric vehicle equipped with in-wheel motors of permanent-magnet type during a class of electrical faults. Due to the constant excitation from the permanent magnets, the output torque from a faulted wheel cannot easily be removed if an inverter shuts down, which directly affects the vehicle s...

This paper presents an analysis of the stability of an electric vehicle equipped with in-wheel motors of permanent-magnet type during a class of electrical faults. Due to the constant excitation from the permanent magnets, the output torque from a faulted wheel cannot easily be removed if an inverter shuts down, which directly affects the vehicle s...