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Study on structural optimization design and cascade PID control of maglev actuator for active vibration isolation system
Abstract
In view of the nonlinear output characteristics of actuators, and due to necessary large strokes for low-frequency vibration isolation platforms in microgravity environment, a method for structural optimization design and cascade PID control of maglev actuators was put forward based on the principle of Lorentz force. Furthermore, the method was utilized to design a magnetic circuit in accordance with the self-demagnetization effect and to multi-objectively optimize the structure parameters of a coil. A mathematical model was established of the remarkably nonlinear output force, due to the nonuniform magnetic fields to optimize its output force and current, so that the time-varying output requirements of controllers may be satisfied. System identification was performed to obtain the mathematical model of its control channel and design cascade PID controllers. This method was applied to lower the phase lag and equivalent time constant of a closed secondary circuit system so that not only the system stability and response rate may be improved, but also the growth of the gain of the controller may lead to growth of the damped natural frequency of the cascade control system; thus, the system settling time may fall and the system control quality may be improved. Simulation was also carried out to the cascade PID control corresponding to the mathematical model so that the cascade PID controller may have a relatively good control effect on disturbing acceleration signals. Experiments were carried out to cascade PID control of maglev actuators to further verify vibration control performances. Comparisons of the measured and simulated acceleration transmissibility data are basically consistent within the band 1–25 Hz. Measured and simulated results indicate that application of the cascade PID control method may attenuate the control object in the range −22.522 to −2.189 dB within the band 1–25 Hz and perform effective vibration control.
... Power lines can be broadly categorized into two types, distribution lines and transmission lines, based on their various uses [17][18][19]. As seen in Figure 1, distribution lines, which typically include 380 V low voltage lines and 10 kV lines, are utilized to distribute power directly to users [20]. ...
... The sensor made by HJduino Corp. is used in accordance with the cutter feeding mechanism's movement characteristics. It has the feature or function that the light source uses a high-brightness condensing LED [18,19], and the receiving tube compares the intensity of various reflected light in order to distinguish between the white wire core and the black insulating skin. When the white wire core is identified, the sensor's output is low, and the cutter stops moving. ...
One of the primary duties in the regular maintenance of electrical distribution networks is the cable stripping operation. In this paper, a unique robot is proposed to overcome drawbacks of the conventional manual operation of cable stripping, such as poor efficiency, low safety, and high labor intensity. This innovative cable-stripping robot is made up of a rotating mechanism, a cable gripping component, and a cutter feeding mechanism that can be adjusted depending on the working environment and workload. The robot’s motors, sensors, main control chip, and wireless communication modules are all carefully selected. A carefully designed cascade controller is created for the robot in an effort to lessen damage to the aluminum core. While the outside location loop uses the PID algorithm, the inner speed control loop uses fuzzy PID. The robot can successfully accomplish cable stripping work and demonstrates its potential to reduce labor intensity. Cable stripping experiments are conducted to validate the effect of the robot and its controller.
... The uncertainty of the structure is considered to ultimately accomplish the stability of the cable-driven robot system. The cascade PID control for maglev actuators is designed in [24], the control effect can be improved by reducing the phase hysteresis of the system and increasing the control gain. Finally, the results of the experimental and numerical simulation show that the regulator functions well in the range of 1~25 Hz. ...
... where a k is a positive design constant, and ( ) ( ) ( ) (23) and satisfies equation (24) where κ is an unknown vector, θ is a known vector. They are both n + 1-dimensional vectors. ...
In this paper, we investigated the cascade controller of a motor-driven deep-sea robot cable system (MDRCS), which consists of the outer loop system and the inner loop system connected by a motor thrust with unknown factors, typically forming a crucial problem along with actuator failures, and is accommodated by a fault control created for the deep-sea model. Furthermore, the non-linear disturbance observer compensates for the external disturbance by using the high-gain state observer to estimate parameters and reduce the effects of measurement inaccuracy from the sensors. We suggested an output feedback boundary controller for the outer loop system to get the thrust and eliminate the transverse cable vibration as well as a multiplicative inverse controller for the motor system to form a cascade controller. The Lyapunov approach is then used to demonstrate the stability of the deep-sea robot cable system and motor system. The results demonstrated the effectiveness of the suggested controller and fault control in the presence of the actuator fault, presented with the appropriate parameters on MDRCS.
... The unmanned aerial vehicles (UAVs) [15,16] require robust control schemes that can alleviate disturbances such as model mismatch, wind disturbances, measurement noise, and the effects of changing electrical variables, e.g., the loss in the battery voltage. Proportional integral and derivative (PID) controller [17][18][19][20] with non-integer order derivative and integration is proposed remedy. Here, the PID control dramatically influences the response of the drone and the time and degree of convergence to the commanded posture. ...
... In this study, the flight velocity, angle, and sensitivity of the metal-detected drones that minimize the height effect of the detection condition were determined and verified using the Taguchi method [18]. For metal detectors, the degree of detection varies greatly depending on the height of the metal, the velocity of the metal detector passing through the metal, the angle of the coil board, and the sensitivity. ...
This paper proposes a methodology to detect metals using a drone equipped with a metal detector and programmed by machine learning (ML) models. Our proposed research process could be considered a safe and efficient unmanned mine detection technology for the eventual removal of landmines. Users of this methodology can remotely control the drones without entering the minefield to detect the metal buried and to distinguish whether the metal is mine or not. To realize this idea, we have first stabilized and improved the attitude control of a drone with an attached metal detector by using the micro genetic algorithm-based optimization of proportional–integral–differential control gains. Next, for metal detection, ML models such as a support vector machine and a back-propagation neural network were trained using the annotated dataset. Finally, we have built a controlled drone equipped with a metal detector and trained ML models and experimentally validated our methodology. According to the experimental results, the present study secured the flight stability of the unmanned metal detection drones and the high detection success rate.
... Because of the characteristics of lowfrequency vibration, active vibration isolation introduces feedback variables through the motion measurement of sensors and suppresses input vibration with a certain control strategy. A method [20] for structural optimization design and cascade PID control of maglev actuators was proposed based on the principle of the Lorentz force. The application of a cascade PID control method managed to attenuate the control object in a range of -22.522 to -2.189 dB within a 1-25 Hz band and perform effective vibration control. ...
... where ,̇, and ̈ are the state variables, u(t) is the measured output, and the parameter b is the control gain. Let 1 = , 2 =̇1, and 3 =̇2 − , where 3 is an extended state regarded as the total disturbance; the extended state-space equation after extension is given as: x bu (20) where ( ) represents the derivative of the total disturbance. From (19), we can establish the 3rd-order LESO: ...
An inertially stabilized platform is subject to the vibration force and moment from its support base, and low-frequency vibrations cannot be eliminated by mechanical vibration isolation. Combining gimbals with magnetic bearings instead of mechanical bearings, a maglev inertially stabilized platform (MISP) is characterized by no friction or an active vibration control capability. In this paper, an improved linear extended state observer (LESO) replacing displacement error with next-order error is proposed to estimate the low-frequency vibration and improve the estimation accuracy. An active vibration isolation control method is then designed to realize cancellation compensation on the MISP. Finally, a simulation example is presented to validate that the proposed measures can effectively eliminate the low-frequency vibration force transmitted from the base and ensure the stability of the MISP.
... Academic Platform Journal of Engineering and Smart Systems 11(1),[27][28][29][30][31][32][33][34] 2023 ...
In this study, a flexible robot arm model and the design of its controller are introduced. The robot arm consists of a single flexible link. It is desired to control the circular position of the robot arm and the vibration of the tip point. Cascade proportional derivative controller was used to control the position and reduce the tip vibration. Controller gains were found using the bees algorithm. The weighted function of system responses such as settling time, maximum overshoot, steady-state error is used as a performance criterion while searching for the best parameters. In addition, controller gains were obtained with the genetic algorithm to evaluate the working performance of the bees algorithm. It has been observed that the Cascade PD controller, whose gains are optimized by the bees algorithm, successfully controls the flexible robot arm system and reduces the vibration of the tip point.
... Based on the thought of cascade control, the control algorithm is usually divided into two parts, including the inner loop (also called the current loop) and the outer loop (also called the position loop) [20][21][22]. When the electromagnet works in the equilibrium position, due to the small variation range of inductance, its inductance can be considered as a constant. ...
In order to decrease the transmission of vibration and achieve the attenuation of the vibration magnitude of an isolated object, a new type of permanent and electromagnet composite vibration isolation system is designed based on negative stiffness theory. Firstly, according to the characteristic analysis, the design of a permanent and electromagnet hybrid actuator is accomplished; secondly, the vibration isolation system model is established, and the active control strategy based on the fuzzy PID algorithm is designed. Finally, a test platform is built to verify the vibration isolation effect. The results indicate that the developed permanent and electromagnet composite vibration isolation system renders the sharp attenuation of external vibration in multiple frequency bands. When the external vibration frequency is within the frequency range of 20 Hz to 100 Hz, the vibration attenuation is greater than 80%; when the external vibration frequency is within the frequency range of 100 Hz to 500 Hz, the vibration attenuation rate is greater than 90%.
... Beijen et al. designed an active vibration isolator with a Steward platform; they used the filtered-error least mean squares (FeLMS) algorithm to design the feedforward controller and experimentally demonstrated vibration suppression under the isolator up to 40 dB at 2-300 Hz [23]. Hu et al. used a cascaded proportional-integral-derivative (PID) control design to drive six maglev actuators, achieving vibration suppression up to −22.5 dB in the range of 1-25 Hz [24]. Jiang et al. designed an active vibration isolation system driven by voice coil motors (VCMs) based on a current sheet model and composite nonlinear feedback controller to achieve a suppression effect of approximately −28 dB at 10 Hz [25]. ...
The optical reference cavity in an ultrastable laser is sensitive to vibrations; the microvibrations in a space platform affect the accuracy and stability of such lasers. In this study, an active vibration isolation controller is proposed to reduce the effect of vibrations on variations in the cavity length and improve the frequency stability of ultrastable lasers. Based on the decentralized control strategy, we designed a state-differential feedback controller with a linear quadratic regulator (LQR) and added a disturbance observer (DOB) to estimate the source noise. Experiments were conducted using an active vibration isolation system; the results verified the feasibility and performance of the designed controller. The accelerations along the axis (Z-, X-, Y-) directions were suppressed in the low-frequency band within 200 Hz, and the root-cumulative power spectral densities (PSDs) declined to 1.17 × 10−5, 7.16 × 10−6, and 8.76 × 10−6 g. This comprehensive vibration met the requirements of an ultrastable laser.
... Thus, multidimensional vibrations should be isolated effectively. Hu et al. 1 proposed a kind of multi-dimensional vibration isolator aiming at reducing the vibrations in microgravity environment. The proposed vibration isolation platform was composed of maglev actuators and controlled by cascade PID algorithm. ...
For isolating multi-dimensional vibrations experienced by precise facilities carried on a vehicle, a novel isolator is proposed based on 2-RPC/2-SPC parallel mechanism with magneto-rheological dampers. Kinematics and dynamics of the isolator are analyzed by geometrics and the Lagrange method. Grey relation analysis approach is conducted to determine the contributions of geometric parameters on natural frequency conveniently. Through analysis, the first order natural frequency of the isolator is affected by the length of the fixed platform most significantly. Due to manufacturing and assembling errors which could not be avoided in the isolator, robust optimal control algorithm is conducted to ensure control effect and robustness of the isolator at the same time. The gain of robust optimal control algorithm is obtained by deducing and solving linear matrix inequality. Compared to passive control, velocity root mean square values of robust optimal semi-active control decreased obviously in horizontal, longitudinal, vertical, and roll directions.
... Classical control methods and modern control methods have been adopted for maglev vibration isolation systems. Traditional PID controllers have been applied to expand control bandwidth [24,25], but only single DOF control simulations were carried out. To improve isolation performance, a PD style double integral acceleration control method was designed by Zhu [6]. ...
The environment in space provides favorable conditions for space missions. However, low frequency vibration poses a great challenge to high sensitivity equipment, resulting in performance degradation of sensitive systems. Due to the ever-increasing requirements to protect sensitive payloads, there is a pressing need for micro-vibration suppression. This paper deals with the modeling and control of a maglev vibration isolation system. A high-precision nonlinear dynamic model with six degrees of freedom was derived, which contains the mathematical model of Lorentz actuators and umbilical cables. Regarding the system performance, a double closed-loop control strategy was proposed, and a sliding mode control algorithm was adopted to improve the vibration isolation performance. A simulation program of the system was developed in a MATLAB environment. A vibration isolation performance in the frequency range of 0.01–100 Hz and a tracking performance below 0.01 Hz were obtained. In order to verify the nonlinear dynamic model and the isolation performance, a principle prototype of the maglev isolation system equipped with accelerometers and position sensors was developed for the experiments. By comparing the simulation results and the experiment results, the nonlinear dynamic model of the maglev vibration isolation system was verified and the control strategy of the system was proved to be highly effective.
The asymmetrical damping of a vibration-isolation system induces a change in the mean position of the isolated body. Inspired by this phenomenon, a novel idea to vertically shift an isolated body based on nonlinear system vibration with asymmetrical damping is proposed. The proposed idea can be applied in fields that require the isolated body’s height to be adjusted. A methodology based on the homotopy analysis method (HAM), which is used to obtain the approximate analytical solution of a piecewise-smooth vibration-isolation system, was developed to verify the feasibility of the proposed idea. The accuracy of the solution obtained by the HAM was verified by the Runge–Kutta method. Furthermore, based on the analytical solution, the effects of critical parameters on the vibration responses of the system were analyzed. Finally, the proposed idea was applied to vehicle height adjustments. Simulation results showed that vehicle height adjustments could be realized only using a semi-active suspension. This provides a novel methodology for vehicle height control.
Electromagnetic suspension is considered as a widely-used type of maglev train systems. It has been successfully used recently in Changsha Maglev Express (CME), China. Great research interests and engineering efforts have been focused on increasing the operation speed of such an environment-friendly low-speed maglev type to 200 km/h in order to meet the requirement of inter-city transportation, which has not been realized yet. However, at a higher speed, there is a considerable levitation force drop at the front of vehicles due to the pronounced eddy current effect. The electromagnet modules are more likely to saturate. An optimized electromagnet design is required for the medium-speed maglev train to achieve better levitation capability, weaker vibration, and more comfortable ride. Based on the actual parameters and operation data of CME, this paper uses the three-dimensional finite element analysis method to fully analyze the occurrence of magnetic saturation and its adverse effects. A novel structure design of electromagnet module coping with the problem of magnetic saturation is proposed to improve the levitation performance. The study also puts forward a three-controller system on the electromagnet module at the front of the vehicles which can effectively ease the imbalance of levitation forces.
The International Space Station (ISS) has been regarding as a laboratory for experiments in numerous microgravity science discipline. However, the microvibration has a serious impact on science experiments on the ISS as well as existing electromagnetic actuators could not satisfy the requirement of good linearity needed for large stroke of low frequency vibration isolation platforms. This paper aims to design a maglev actuator with good linearity, which could be applied to microgravity vibration isolation platforms. Based on the principle of Lorentz force and self-demagnetization effect, the structural form and preliminary design indices of the actuator were presented. In order to minimize the weight and heat consumption of its coil, parametric design was carried out and multi-objective optimization was adopted for it. Moreover, to investigate the dynamic characteristics of the actuator, system identification was performed to obtain a mathematical model of its control channel, which has good fitting degree of the time and frequency domain signals. Therefore, the result provides an important basis for structural optimal design of the actuator for microgravity vibration isolation system.
High precision measurement of acceleration levels is required to allow active control for vibration isolation platforms. It is necessary to propose an accelerometer configuration measurement model that yields such a high measuring precision. In this paper, an accelerometer configuration to improve measurement accuracy is proposed. The corresponding calculation formulas of the angular acceleration were derived through theoretical analysis. A method is presented to minimize angular acceleration noise based on analysis of the root mean square noise of the angular acceleration. Moreover, the influence of installation position errors and accelerometer orientation errors on the calculation precision of the angular acceleration is studied. Comparisons of the output differences between the proposed configuration and the previous planar triangle configuration under the same installation errors are conducted by simulation. The simulation results show that installation errors have a relatively small impact on the calculation accuracy of the proposed configuration. To further verify the high calculation precision of the proposed configuration, experiments are carried out for both the proposed configuration and the planar triangle configuration. On the basis of the results of simulations and experiments, it can be concluded that the proposed configuration has higher angular acceleration calculation precision and can be applied to different platforms.
The microvibration has a serious impact on science experiments on the space station and on image quality of high resolution satellites. As an important component of the active vibration isolation platform, the maglev actuator has a large stroke and exhibits excellent isolating performance benefiting from its noncontact characteristic. A maglev actuator with good linearity was designed in this paper. Fundamental features of the maglev actuator were obtained by finite element simulation. In order to minimize the coil weight and the heat dissipation of the maglev actuator, parametric design was carried out and multiobjective optimization based on the genetic algorithm was adopted. The optimized actuator has better mechanical properties than the initial one. Active vibration isolation platforms for different-scale payload were designed by changing the arrangement of the maglev actuators. The prototype to isolate vibration for small-scale payload was manufactured and the experiments for verifying the characteristics of the actuators were set up. The linearity of the actuator and the mechanical dynamic response of the vibration isolation platform were obtained. The experimental results highlight the effectiveness of the proposed design.
The Microgravity Vibration Isolation Subsystem (MVIS), integrated within the European Space Agency's Fluid Science Laboratory (FSL) inside the Columbus Laboratory, was delivered to the International Space Station in February 2008. MVIS is designed to actively isolate vibrations with closed loop control for experiments in the FSL's Facility Core Element (FCE) by monitoring acceleration levels and compensating for them using Lorentz force actuator assemblies. The objectives of this paper are to discuss the rationale for developing MVIS technology, provide an overview of its features, integration and operational concept, update the operations community with its commissioning status, and provide information to experiment developers such that the benefits of MVIS can be maximized. MVIS commissioning Phase 1 was completed in January 2010 with MVIS team support at the FSL Facility Responsible Centre at the Microgravity Advanced Research and Support (MARS) centre along with support from the Canadian Space Agency's (CSA) Payload Telescience Operations Centre. The MVIS hardware is functioning nominally and MVIS centered the FCE with closed loop control and provided measurable vibration attenuation. Preparations are underway for Phase 2 during which time MVIS isolation performance will be tested. Phase 3 will identify an experiment's impact on the system (e.g. configuration, front FCE umbilicals) and assess the fully integrated isolation performance. Since the MVIS isolation performance and operational envelope are directly related to umbilical characteristics, umbilical design recommendations and best practices for experiment developers are provided. The completion of Phase 1 is the culmination of many years of hard work by the large number of individuals who have participated in this program. There continues to be an excellent working relationship between CSA, Bristol Aerospace Limited, ESA, MARS, and Thales Alenia Space. The success of Phase 1 activities paves the way towards future MVIS commissioning activities and routine operations. © 2010 by Government of Canada. Published by the American Institute of Aeronautics and Astronautics, Inc.
Vibration in the microgravity environment is with the characteristics of low frequency, small amplitude, and randomness. Control method of an active vibration isolation system with parallel mechanism applied to space application, which is effective for disturbance suppression, is proposed. The dynamics model of active vibration isolation system with payload is represented via Kane’s method, thereafter the description in state-space linearization is introduced. System properties and step responses of the systems in open loop are evaluated in detail. Controllability and observability of the system are checked by state-space equations of the system. The state feedback decoupling with double-loop proportionalintegral-derivative (PID) control method is adopted as the system controller to design the decoupling matrix and the PID controller. For improving the properties of the system, a control system with H-infinity method is also designed and evaluated. Finally, various types of simulation results are demonstrated to verify the effectiveness of the active vibration damping system proposed.
The International Space Station (ISS) is being envisioned as a laboratory for experiments in numerous microgravity (μg) science disciplines. Predictions of the ISS acceleration environment indicate that the ambient acceleration levels will exceed levels that can be tolerated by the science experiments. Hence, microgravity
vibration isolation systems are being developed to attenuate the accelerations to acceptable levels. While passive isolation systems are beneficial in certain applications, active isolation systems are required to provide attenuation at low frequencies and to mitigate directly induced payload disturbances. To date, three active isolation systems have been successfully tested in the orbital environment. A fourth system called g-LIMIT is currently being developed for the Microgravity Science Glovebox and is manifested for launch on the UF-1 mission. This paper presents an overview of microgravity
vibration isolation technology and the g-LIMIT system in particular.
Most active vibration isolation systems that try to a provide quiescent acceleration environment for space science experiments have utilized linear design methods. In this paper, we address adaptive control augmentation of an existing classical controller that employs a high-gain acceleration feedback together with a low-gain position feedback to center the isolated platform. The control design feature includes parametric and dynamic uncertainties because the hardware of the isolation system is built as a payload-level isolator, and the acceleration Sensor exhibits a significant bias. A neural network is incorporated to adaptively compensate for the system uncertainties, and a high-pass filter is introduced to mitigate the effect of the measurement bias. Simulations show that the adaptive control improves the performance of the existing acceleration controller and keep the level of the isolated platform deviation to that of the existing control system.
We present a prototype of 6-DOF magnetically levitated stage based on single axis Lorentz force actuator is capable of positioning down to micron in several millimeter travel range with a simple and compact structure. The implementation of the Lorentz force actuators, instrument modeling, and motion controller of the maglev system are described. With the force-gap relationship of the actuator solved by Gaussian quadrature, 2-demsional (2D) lookup table is employed to store the result for the designing of control system. Based on the force-gap relationship, we choose the suitable stroke of each actuator to develop the stability of the maglev stage. Complete decoupling matrix is analyzed here to establish a decoupled dynamics between resulting six axis motion and eight outputs to the actuators. The design travel volume of the stage is 2mm×2mm×2mm in translation and 80mrad× 80mrad×40mrad in rotation. With a constant gain and critical damping PID controller, the resolution of the translation is 2.8um and 4um root mean square in horizontal and vertical direction respectively. Experimental results are presented to illustrate the positioning fluctuations, step responds and multi axis motion. Some comparative tests are taken to highlight the advantage resulted from the accurate force-gap relationship, suitable stroke, and complete decoupling matrix.
A novel 6 degree of freedom (6-DOF) passive vibration isolator is studied theoretically and validated with experiments. Based on the Stewart platform configuration, the 6-DOF isolator is constructed by 6 X-shape structures as legs, which can realize very good and tunable vibration isolation performance in all 6 directions with a passive manner. The mechanic model is established for static analysis of the working range, static stiffness and loading capacity. Thereafter, the equation of motion of the isolator is derived with the Hamilton principle. The equivalent stiffness and the displacement transmissibility in the six decoupled DOFs direction are then discussed with experimental results for validation. The results reveal that (a) by designing the structure parameters, the system can possess flexible stiffness such as negative, quasi-zero and positive stiffness, (b) due to the combination of the Stewart platform and the X-shape structure, the system can have very good vibration isolation performance in all the 6 directions and in a passive manner, and (c) compared with the simplified linear-stiffness legs, the nonlinearity of the X-shape structures enhance the passive isolator to have much better vibration isolation performance.
A feedforward adaptive active vibration control (AVC) algorithm using maglev actuator is proposed to attenuate periodic disturbance in this paper. Maglev actuator is viewed as a single-input-single-output (SISO) system with time-varying nonlinearity in the proposed algorithm. A radial basis function (RBF) neural network is used as the controller, whose hidden-layer centers and output-layer weights are adapted according to clustering algorithms and stochastic gradient algorithms respectively. In the proposed algorithm, there is no need to model the maglev actuator under normal circumstance, which is critical and difficult in conventional maglev control. The results of simulations and experiments based on a single degree-of-freedom vibration isolation system show that the adaptive algorithm can greatly attenuate the periodic disturbance, and can efficiently compensate for the actuator's time-varying nonlinearity at the same time.
Real-time hybrid simulation (RTHS) is a testing method which combines the response from an experiment (i.e., experimental substructure) with that of a computer model (i.e., analytical substructure) in real-time. The accuracy and stability of the RTHS are prone to the propagation of error in the measured signals. Thus, critical developments in servo-hydraulic actuator control are needed to enable a wide application of this testing technique. In this study, a new tracking error compensation strategy for servo-hydraulic actuator control is developed, and numerically and experimentally evaluated. This compensation procedure is formulated based on a new set of tracking error indicators, namely, frequency domain-based (FDB) error indicators, which uncouple phase (lag and lead) and amplitude (overshoot and undershoot) errors and quantify them. These indicators are then incorporated into a two degree-of-freedom (d.f.) controller to develop closed-form equations to design an adaptive servo-hydraulic controller with improved tracking performance. The FDB indicators and the new adaptive controller are studied through numerical simulations in Simulink and LabVIEW and also verified experimentally. The proposed controller is computationally efficient, it can be implemented in real-time and it does not require any user-defined (i.e., predetermined) coefficients. As a result of its two d.f. formulation, this adaptive controller can be introduced to any closed-loop servo-controller through a digital or analog interface depending on the experimental setup properties. As such, it can be used to improve the tracking capability of any single hydraulic actuator system, which is essential in RTHS.
Recently, fractional-order proportional–integral–derivative (FOPID) controllers are demonstrated as a general form of the classical proportional–integral–derivative (PID) using fractional calculus. In FOPID controller, the orders of the derivative and integral portions are not integers which offer more flexibility in succeeding control objectives. This paper proposes a multi-objective genetic algorithm (MOGA) to optimize the FOPID controller gains to enhance the ride comfort of heavy vehicles. The usage of magnetorheological (MR) damper in seat suspension system provides considerable benefits in this area. The proposed semi-active control algorithm consists of a system controller that determines the desired damping force using a FOPID controller tuned using a MOGA, and a continuous state damper controller that calculates the input voltage to the damper coil. A mathematical model of a six degrees–of–freedom seat suspension system incorporating human body model using an MR damper is derived and simulated using Matlab/Simulink software. The proposed semi–active MR seat suspension is compared to the classical PID, optimum PID tuned using genetic algorithm (GA) and passive seat suspension systems for predetermined chassis displacement. System performance criteria are examined in both time and frequency domains, in order to verify the success of the proposed FOPID algorithm. The simulation results prove that the proposed FOPID controller of MR seat suspension offers a superior performance of the ride comfort over the integer controllers.
This paper proposes the concept development and design of a VCM actuator for Active Vibration Isolation System (AVIS). Active vibration isolating method was constructed passive isolator and active isolator. Spring was used for isolating passively and actuator like voice coil motor was used for active isolating. The proposed active vibration isolating system could isolate a six degree-of-freedom disturbance effectively. In case of AVIS, payload is variable according to the type of instruments. Therefore, actuator should maintain uniform performance with payload change. The proposed VCM actuator satisfied this performance through relative relation between magnet array and coils. In addition, for maximizing actuator performance, actuator should generate large force density. Therefore, we apply the Halbach magnet array to proposed actuator. The Halbach magnet array helps with reinforcing magnetic flux field. The reinforced magnetic field takes a role to generate more powerful Lorentz force to isolate disturbance. Finally, in this paper, we propose the actuator that novel type using voice coil motor with the Halbach magnet array and optimize each design variables to generate maximum output. These AVIS can use to eliminate disturbance in Maglev stage. Maglev stage need AVIS to increase its performance is necessary. In the future, AVIS and Maglev system will be integrated.
The Microgravity Science Program (MSP) of the Canadian Space Agency (CSA) is developing a Microgravity vibration Isolation Mount (MIM) base unit designed to support small payloads in the EXPRESS rack taking into account the allowed resources, interface definitions, etc. A double middeck locker will house the MIM base unit, which will use a single middeck locker, as well as, an experimental facility which will use the other middeck locker, similar to the Mir Phase A facility where a MIM was visited by many types of experimental facilities. The MIM base unit will provide g-jitter isolation, as well as, controlled g-inputs into the experiments for their study. The MIM base unit will also be counter balanced for experiments needing large g-inputs during the microgravity period of the station. The MIM base unit will offer an enclosure which will limit heat losses from the payload to the cabin and protect the experiment from incidental disturbances. The MIM base unit will support experiments by providing common services such as power, data collection and analysis, as well as, control of the experiment. These services reduce duplication within the experimental facilities, making them lighter, smaller and cheaper. .
The subject discussed in this paper is the design, construction and test of a free floating micro-gravity isolation platform to reduce the acceleration dose on zero gravity experiments on e.g. the International Space Station (ISS). During the project a system is specified and constructed whereupon it is tested in the sixth student parabolic flight campaign issued by the European Space Agency (ESA). The system consists of six custom made electro magnetic actuators which acts on the isolated platform based on the designed controller and their input from six accelerometers and six infrared position sensors. From the data acquired during the flights it is concluded that the control algorithm used to position the platform fulfills the requirements, but it is not yet possible to draw final conclusions on the performance of the acceleration controller. It does, however, indicate a better performance, but better sensors are required.
Space flight experiment test results of a prototype space station Active Rack Isolation System (ARIS) are presented. The purpose of ARIS is to isolate microgravity sensitive science experiments mounted in the International Standard Payload Rack (ISPR) from the structural vibrations present on the large space station orbital structure. Space flight testing was necessary because ARIS cannot be tested in all six degrees-of-freedom simultaneously on the ground. The foremost objectives of the experiment were (1) to determine if the system would be stable when all six axis are controlled, (2) to determine if the systems position response to accelerometer drift would result in excessive motion, (3) to measure isolation performance and determine the impact of attaching umbilicals, and (4) to measure the quiescent background acceleration levels induced by the controller itself. Results related to these objectives are presented along with a description of the control architecture. A brief historical perspective, a description of ARIS, and a flight test summary are also presented.
In view of the utility of space vehicles as orbiting science laboratories, the need for vibration isolation systems for acceleration-sensitive experiments has gained increasing visibility. To date, three active microgravity vibration isolation systems have successfully been demonstrated in flight. A tutorial discussion of the microgravity vibration isolation problem, including a description of the acceleration environment of the International Space Station and attenuation requirements, as well as a comparison or the dynamics of passive isolation, active rack-level isolation, and active payload-level isolation is provided. The flight test results of the three demonstrated systems: suppression of transient accelerations by levitation, the microgravity vibration isolation mount, and the active rack isolation system are surveyed.
Electromagnetic actuator device
- J Boll
- R Bory
- D Haerter
The design and simulation test of the controller for active vibration isolation system in high microgravity platform
- J Wang
Study on actuators of active payload-level vibration isolation system for experiments in space
- J Chen