Actuator For Active Suspension Research Articles

Integrated robust dynamics control of all-wheel-independently-actuated unmanned ground vehicle in diagonal steering

In the future civilian Intelligent Transportation System (ITS) and military area, the Unmanned Ground Vehicles (UGVs) are supposed to replace humans to conduct various tasks in wide civilian or military applications. This paper aims at improving the overall performance of the All-wheel-independently-actuated (AWIA) UGV. Each wheel of the AWIA UGV is independently driven and steered by the motors with independent active suspension equipped to achieve the great potential of mobility, maneuverability, and controllability. Aiming to improve the performance of AWIA UGV in diagonal steering mode under critical circumstances, a novel integrated control approach is extended in this paper based on robust H2/H∞ theory. The major control objective is to generate additional vehicle active moment by full X-by-wire technique to collaboratively control lateral and roll motion of the vehicle to maintain a target diagonal steering performance. A wheel force distribution controller in the control executive layer interfaced to actuators is applied to achieve the resultant active control moment at each wheel corner, by controlling each independent drive motor, independent steer motor, and active suspension actuator. The effectiveness of the proposed control approach is validated by an AWIA UGV testbed by performing the step-steer experiments.

Nonlinear Model Predictive Control for Integrated Energy-Efficient Torque-Vectoring and Anti-Roll Moment Distribution

This study applies nonlinear model predictive control (NMPC) to the torque-vectoring (TV) and front-to-total anti-roll moment distribution control of a four-wheel-drive electric vehicle with in-wheel-motors, a brake-by-wire system, and active suspension actuators. The NMPC cost function formulation is based on energy efficiency criteria, and strives to minimize the power losses caused by the longitudinal and lateral tire slips, friction brakes, and electric powertrains, while enhancing the vehicle cornering response in steady-state and transient conditions. The controller is assessed through simulations using an experimentally validated high-fidelity vehicle model, along ramp steer and multiple step steer maneuvers, including and excluding the direct yaw moment and active anti-roll moment distribution actuations. The results show: 1) the substantial enhancement of energy saving and vehicle stabilization performance brought by the integration of the active suspension contribution and TV; 2) the significance of the power loss terms of the NMPC formulation on the results; and 3) the effectiveness of the NMPC with respect to the benchmarking feedback and rule based controllers.

Experimental assessment of a linear actuator driven by magnetorheological clutches for automotive active suspensions.

The main functions of automotive suspensions are to improve passenger comfort as well as vehicle dynamic performance. Simultaneously satisfying these functions is not possible because they require opposing suspension adjustments. This fundamental design trade-off can be solved with an active suspension system providing real-time modifications of the suspension behavior and vehicle attitude corrections. However, current active suspension actuator technologies have yet to reach a wide-spread commercial adoption due to excessive costs and performance limitations. This paper presents a design study assessing the potential of magnetorheological clutch actuators for automotive active suspension applications. An experimentally validated dynamic model is used to derive meaningful design requirements. An actuator design is proposed and built using a motor to feed counter-rotating MR clutches to provide upward and downward forces. Experimental characterization shows that all intended design requirements are met, and that the actuator can output a peak force of ±5300 N, a peak linear speed of ±1.9 m/s and a blocked-output force bandwidth of 92 Hz. When compared to other relevant technologies, the MR approach simultaneously shows both better force density and speeds (bandwidth) while adding minimal costs and weight. Results from this experimental assessment suggest that MR slippage actuation is promising for automotive active suspensions.

Thrust Ripple Force Minimization and Efficiency Analysis of Electromagnetic Actuator on Active Suspension

A novel electromagnetic actuator for active suspension is designed on an in-wheel motor electric vehicle in this paper. Aiming at reducing thrust ripple force and improving stability of the actuator, a method of calculating the optimum slot width and optimizing edge radian of end tooth is proposed. Firstly, a finite element model (FEM) of the actuator is modeled, and the correctness of FEM is verified through comparisons of simulation results and analytical ones, including counterelectromotive force of coil winding and force characteristic test of the actuator. Based on the FEM, the influence of slot width on electromagnetic thrust and total harmonic distortion (THD) is analyzed, and the slot width is improved. The side effect of the actuator is considered. By improving the edge radian, the fluctuation of the cogging force and thrust ripple is reduced. In addition, output efficiency and energy feed efficiency of the actuator after reducing thrust ripple are studied. The results show the minimum THD is 4.2%, which is obtained at the slot width 4.3 mm, and thrust ripple is 36.5 N. When the edge radian is 60°, the thrust ripple decreases to only 15.7 N, which is reduced by 57.0%. The maximum output efficiency and energy feedback efficiency of the actuator are 87.5% and 27.1%, respectively. Finally, according to actuator characteristic tests of two working modes, it is concluded that the maximum energy feedback efficiency is 25.6%. The input current and current frequency should be gradually increased with the increase of suspension speed under active mode, and the maximum output efficiency is 80.2%. The test results are basically consistent with the FEM analysis values, which verify the correctness of the FEM analysis.

A novel approach to design and control of an active suspension using linear pump control–based hydraulic system

This paper presents a novel design and control method of an active suspension system using a linear pump control–based hydraulic system for a cost-effective application. Various active suspension systems have been proposed and applied to vehicles due to its ability to improve ride comfort and handling performance even though these active suspension systems are not popular because of their complexity, high cost, heavyweight, and low power efficiency. A new type of active suspension actuator system was designed and validated herein based on the methods of actuator sizing and modified control scheme to address the aforementioned issues. System power capability has been analyzed under various dynamics and road conditions. Active suspension actuator components have been designed based on the results. The electro-hydraulic system is powered by a battery to reduce the energy consumption of the system; hence, it is operated by torque on demand. A double-acting linear hydraulic motor pump with a dual rack and pinion has been proposed for hydraulic force control with a simple on/off switch operation. The actuator force has been controlled by continuous linear motor pump displacement control via torque control using a three-phase synchronous brushless alternative current motor. Dynamic performance evaluation of the actuator system has been conducted using AMESIM and actual rig test. Active height and roll control algorithms for the enhancement of vehicle dynamics considering actuator dynamics have also been developed and validated through the rig and real vehicle tests. The evaluation results showed that the linear motor pump–based active suspension system performs as well as the previous complicated hydraulic active suspension system. The new active system proposed in this study was able to improve the vehicle dynamics using cost-effective actuation system significantly.

Simultaneous dynamic system estimation and optimal control of vehicle active suspension

ABSTRACTThis paper proposes a combined observer/controller method that estimates the states and simultaneously improves the ride comfort and stability of a full vehicle active suspension system using a single inertial measurement unit (IMU) in the presence of noise and centre of gravity uncertainties. The derived model is based on a channel-by-channel estimation technique using filtered white noise excitation signals on all the wheels, as well as active suspension actuators. The transfer functions of the vehicle system are estimated by analysing the IMU signals in the frequency domain. The derived result is then used in a linear quadratic regulator to calculate the actuators' forces to improve the vehicle's ride comfort and road holding stability within the limits of the rattle space. The simulation results show the efficacy of the proposed approach. Specifically, the observer estimates the actual behaviour of the vehicle with accuracy with up to uncertainty. Finally, a parametric study has been investigated to ascertain the applicability of the proposed approach in estimating the vehicle dynamics with simultaneously improving the ride comfort and road holding stability.

Higher order sliding mode control for active suspension systems subject to actuator faults and disturbances

As the possibility of faults in active suspension actuators are higher and more severe compared to other components, this study presents a fault-tolerant control approach based on the second-order sliding mode control method. The aim of the controller is to improve riding comfort, guarantee handling stability, and provide adequate suspension stroke in the presence of disturbances and actuator faults. A nonlinear full-vehicle suspension system and hydraulic actuator with nonlinear characteristics are adopted for accurate control. Firstly, a nonlinear sliding manifold based on a nonsingular fast terminal sliding mode controller is introduced to suppress the sprung mass heave, pitch, and roll motions arising from road disturbances. Secondly, a second-order sliding mode-based super twisting controller is utilized to track the desired forces generated by the nonsingular fast terminal sliding mode controller with actuator faults and uncertainties. The controllers are robust against disturbances, uncertainties, and faults. Moreover, the stability of the super twisting controller is proved by the strong Lyapunov functions. Finally, numerical simulations are performed to demonstrate the effectiveness of the controller. Four different conditions, random road profile, bump road excitation, single-wheel bump excitation, and partial faults are considered. The main contributions of this study are: (1) combination of the above algorithms to deal with actuator faults and improve active suspension performance; (2) the controller proposed in this study has a simple structure. Simulation results indicate that the nonsingular fast terminal sliding mode super twisting controller can guarantee the performance of the closed-loop system under both faulty and healthy conditions.

Evaluation of Human Exposure to Vibration Subjected to Active Suspension Actuators

This paper details the assessment of human response to vibration through modelling of seated human body using seven degrees of freedom lumped mass model. Continued human exposure to chronic vibrations may subsequently leads to person’s discomfort. To avoid this discomfort, an active suspension with combination of electro-hydraulic, pneumatic or air spring actuator is introduced between sprung mass and the unsprung mass which is controlled by a PID controller. For the simulation, ISO D-class road is given as input for the designed Matlab Simulink model and the results were compared. The simulation result shows that air spring actuators based active suspension can effectively attenuate the vertical vibration acceleration and increase the riding comfort.

Fractional-order control of active suspension actuator based on parallel adaptive clonal selection algorithm

In current study, a new approach for vehicle active suspension actuator control is reported. For this approach, a nonlinear model for an electro-hydraulic servo actuator and quarter suspension system is established. An Oustaloup recursive approximation (ORA) Fractionalorder proportional–integral–derivative (FOPID) controller is designed to control the displacement of the actuator, and controller parameters are optimized based on error integral criteria using the Parallel adaptive clonal selection algorithm (PACSA). The research indicates that PACSA can tune parameters of the FOPID controller accurately and efficiently, and the tuned FOPID controller performs better in terms of response speed and tracking accuracy than a regular Proportional–integral–derivative (PID) controller. The performance of the active suspension system that uses the FOPID actuator is obviously superior to that of the active suspension system that uses a PID actuator and a passive suspension system.

WITHDRAWN: Stable switched tracking of vehicle roll dynamics using active suspension actuators

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Development of Electric Active Suspension Actuator

Development of Electric Active Suspension Actuator

Development on Electromotor Actuator for Active Suspension of Vehicle

In view of the shortcomings of actuator for hydraulic active suspension of vehicle,such as slow response,high energy consumption,low efficiency of energy accumulation,and complex structure,a novel design scheme of active suspension with energy accumulation by electromotor actuator(mainly composed of a brushless motor and a ball screw)is presented.Taking the semi-independent rear suspension of a certain intermediate car as example,structural designs of the important components of electromotor actuator,such as the elastic elements,ball screw and brushless motor are carried out,and the output characteristics are analyzed and derived.A functional prototype of actuator is trial-produced,and the electric and passive response characteristics of actuator are tested and analyzed.The feasibility and effectivity of actuator are proved.Moreover,the design defects that need to be further improved,and the performance indexes that need to he further tested,such as the active response and electromagnetic energy accumulation,are expounded.

Development of the Electric Active Suspension Actuator

Development of the Electric Active Suspension Actuator

An Application of Oil-Hydraulic Actuator for Active Suspension of Railway Vehicle. Experimental Study with Actual-Size Vehicle Model on Test Stand.

Active suspensions have been studied to improve the ride quality of railway vehicles. In many cases, pneumatic actuators were employed in those studies. This paper deals with the application of oil-hydraulic actuators, which are expected to have stronger control effect on the running vibration. This is examined experimentally by using an actual-size vehicle model on a test stand. The LQG control law, in which state variables are estimated from measurable accelerations on actual railway vehicles, is adopted. The LQ control law, in which state variables are measured accelerations and their integrated quantities, is also adopted. The results show that both controllers have good vibration isolation performance in both harmonic and random excitations. The control force and the stability are improved by decreasing the lateral damping in parallel with the actuator in the secondary suspension. In this case, it is confirmed that the relative displacement between the car body and bogie does not increase.

Application of Oil-Hydraulic Actuator for Active Suspension of Railway Vehicle. Adoption of LQG Control Law to a Scale Model on a Test Apparatus.

Active suspensions have been studied to improve the ride quality of railway vehicles. In many cases, pneumatic actuators were employed in these studies. This paper deals with the application of oil-hydraulic actuators, which are expected to have more control effect on the running vibration. They have been examined experimentally by using a 3 d. o. f. half-vehicle model. The LQG control law, in which state variables were estimated from measurable ones on actual railway vehicles, was adopted. The results show the possibility that the controllable frequency range is extended by the oil-hydraulic actuator under practical conditions. The addition of bogie acceleration measurement to body-related measurements provides a significant advantage for the performance. When actual body weight becomes lighter than that of the controller design value, the control performance and the stability deteriorate. Therefore, it is recommended that the empty car body weight be used for design of the active suspension controller. Moreover, the control effect can attain the maximum vibration isolation level if the sampling period is shortened to 2 ms.

Application of Oil-Hydraulic Actuator for Active Suspension of Railway Vehicle. Investigation with Optimal Regulator Using a Scale Model on a Test Apparatus.

Active suspensions have been studied to improve the ride quality of railway vehicles. In many cases, pneumatic actuators were employed in those studies. This paper deals with the applicability of oil-hydraulic actuators that are expected to have more control on the running vibration for active suspension. This was examined experimentally with the optimal control theory using a 3 d. o. f. half-car scale model. The results show that the controllable frequency range extends with adequate control. Especially, in a case where the actuator properties were considered in the feedback gains, superior property of the vibration isolation was obtained in the middle frequency range of 3 Hz to 13Hz. Here, the selection of valve equivalent resistance is significant in feedback gains, because the actual valve resistance changes with oil flow passing through the servo valve. Some cases based on output feedback show more effctive results than the full-state feedback in the lower frequency range.