Electrohydraulic Active Suspension Research Articles

Active suspension hierarchical control with parameter uncertainty and external disturbance of electro-hydraulic actuators

In order to improve the ride comfort and handling stability of the electro-hydraulic active suspension system, a hierarchical control strategy is proposed. For the active suspension system with body mass uncertainty and safety constraints, an enhanced constraint adaptive backstepping controller is designed to generate the target force of body vertical motion. When dealing with constraints, nonlinear filters are introduced, backstepping technology and quadratic Lyapunov function are used to combine the control target and domain constraints, and the vertical displacement of the body and the suspension deflection control index are synthesized into a single controlled variable, so that the control variable converging to zero meets the suspension dynamic displacement limit. The ride comfort and safety of the active suspension system are improved. Secondly, stability analysis is conducted on the zero dynamic error system to ensure that all safety performance indicators are bounded. The effects of external disturbances, parameter uncertainties and modelling errors on the force tracking accuracy of asymmetric cylinder electrohydraulic systems are addressed. A backstepping dynamic surface control method based on a nonlinear perturbation observer is proposed, which estimates the composite perturbation terms such as modelling error and external perturbation, and uses the estimated value of the nonlinear observer to design a feedforward compensating control term to offset the effect of the composite perturbation on the system performance. In addition, the dynamic surface control method is used to calculate the derivative of the target force input, which avoids the derivative explosion phenomenon and reduces the computational complexity of the system. Simulation test results show that this method reduces the computational complexity of the system and improves the control performance. And under random and bumpy road conditions, the root-mean-square value of sprung mass acceleration performance index is reduced by 48.354 % and 72.677 % compared with passive suspension, which improves the ride comfort of the vehicle.

Adaptive robust precision control of an active spray boom suspension with disturbance estimation

When the boom sprayer works in the field, the boom must be parallel to the undulating ground or crop canopy. Aiming at the problem of low control accuracy and poor stability caused by parameter uncertainties and time-varying disturbances in the electro-hydraulic active boom suspension system, this paper proposes an adaptive robust precision control algorithm based on disturbance estimation. Firstly, the dynamic analysis modeling method is adopted to establish the nonlinear dynamic model and mechanism geometric equation of the pendulum active and passive suspension. Then, the controller was designed based on the nonlinear model of the suspension system. The proposed controller uses the backstepping design method to integrate the disturbance observer into the adaptive robust controller, which can effectively deal with the parameter uncertainties and time-varying disturbances in the suspension system model. Finally, a large number of experiments were carried out by taking a 28 m large boom active suspension driven by a single-rod hydraulic pressure as an example. Using an established rapid control prototype of a large boom suspension, a variety of control algorithm comparison experiments were carried out, and a 6-DOF motion platform was used to simulate the motion coupling interference of the sprayer chassis. The experiment results illustrate the high-performance characteristics of the proposed controller and improve the tracking performance of the active pendulum suspension system under various parameter uncertainties and time-varying disturbances.

전자 유압 엑추에이터를 포함하는 비선형 능동 서스펜션의 상태추정을 위한 가우시안 분포 리샘플링 기반 입자 필터 설계

This paper proposes a GDRPF (Gaussian Distribution Resampling Particle Filter) for electro-hydraulic active suspension systems. In order to estimate the state of the nonlinear/non-Gaussian suspension system effectively, a particle filter-based state estimator was developed, and the computational burden and sample impoverishment problems were overcome through the GDR algorithm. The proposed GDRPF-based state estimator not only reduces the computational burden of the particle filters efficiently, but also has better estimate performance than other linearization-based state estimators. Simulation results for nonlinear active suspension system demonstrate the effectiveness of the proposed algorithm.

Fuzzy Finite Memory State Estimation for Electro-Hydraulic Active Suspension Systems

This paper presents a novel nonlinear estimator called the fuzzy finite memory (FFM) state estimator for electro-hydraulic active suspension systems, based on fuzzy techniques and finite impulse response. The Takagi-Sugeno fuzzy model is introduced to effectively describe highly nonlinear suspension systems with electro-hydraulic actuator dynamics. Compared with the conventional state estimator, which has an infinite memory structure and requires whole data from the initial to current time, the proposed fuzzy state estimator with a finite memory structure guarantees robustness against external disturbances and modeling uncertainty. The simulation results verify that the developed fuzzy finite memory state estimator is more robust under external disturbances and modeling uncertainties than the existing infinite impulse response nonlinear estimator.

Adaptive neural network and nonlinear electrohydraulic active suspension control system

In this article, an adaptive neural network control system is proposed for a quarter car electrohydraulic active suspension system coping with dynamic nonlinearities and uncertainties. The proposed control system is primarily designed to stabilize a sprung mass position of the quarter car electrohydraulic active suspension. Linear controllers such as the proportional–integral–differential controller have limited control performances. The limited control performances are caused by dynamic phenomena such as nonlinearity, parametric uncertainties, and stiff external disturbances. To overcome these dynamic phenomena, we propose a combined adaptive radial basis function neural network with a backstepping control system for a quarter car active suspension system. This setup can handle the unmatched model uncertainty of the system, while the adaptive neural network can take care of its unknown smoothing functions. In general, radial basis function neural network can represent a complicated function, and therefore, semi-strict-feedback dynamic systems are considered to simplify the adaptive neural network control design. Simulation results are indicated to illustrate adaptive neural network control effectiveness.

A Novel Adaptive and Nonlinear Electrohydraulic Active Suspension Control System with Zero Dynamic Tire Liftoff

In this paper, a novel adaptive control system (NAC) is proposed for a restricted quarter-car electrohydraulic active suspension system. The main contribution of this NAC is its explicit tackling of the trade-off between passenger comfort/road holding and passenger comfort/suspension travel. Reducing suspension travel oscillations is another control target that was considered. Many researchers have developed control laws for constrained active suspension systems. However, most of the studies in the works of the latter have not directly examined the compromise between road holding, suspension travel, and passenger comfort. In this study, we proposed a novel adaptive control system to explicitly address the trade-off between passenger comfort and road holding, as well as the compromise between passenger comfort and suspension travel limits. The novelty of our control technique lies in its introduction of a modeling system for a dynamic landing tire system aimed at avoiding a dynamic tire liftoff. The proposed control consists of an adaptive neural networks’ backstepping control, coupled with a nonlinear control filter system aimed at tracking the output position of the nonlinear filter. The tracking control position is the difference between the sprung mass position and the output nonlinear filter signal. The results indicate that the novel adaptive control (NAC) can achieve the handling of car–road stability, ride comfort, and safe suspension travel compared to that of the other studies, demonstrating the controller’s effectiveness.

Design and experiment of electro hydraulic active suspension for controlling the rolling motion of spray boom

Boom sprayer is one of the most commonly used plant protection machinery for spraying pesticide. Studies have shown that the efficiency of chemicals is highly correlated with the uniformity of spray distribution patterns. As the boom is a large and flexible structure, boom rolling leads to overlapping and leakage of the pesticides. In order to improve spray uniformity, the boom attitude should be kept parallel to the ground slope or to the crop canopy beneath the boom. Passive suspension can attenuate frequencies above its resonance frequency, but nothing can be done to align the boom to the sloping ground. Therefore, an active suspension system is designed, which includes DSP-based controller, a servo valve, a hydraulic cylinder, two ultrasonic sensors, one inertial attitude sensor, and the developed control procedures. In order to prevent the wrong response of the control system caused by the high frequency component due to uneven crop canopy or rough ground. A special signal processing algorithm was proposed, including the limiting filter, smoothing algorithm and data fusion algorithm based on optimal weight. The transient and steady-state performances of the boom control system using velocity feedforward PID algorithm were tested on a six DOF motion simulator. It can be seen that the low-frequency tracking performance of the boom was greatly improved after the electro-hydraulic active suspension was added. At the resonance frequency, the peak angle of active suspension and passive suspensions are 0.72° and 1.29° respectively, and the resonance peak is greatly reduced. The controller was implemented on a self-propelled boom sprayer and validated under field conditions, the standard deviation of the roll angle of the boom with active suspension is 0.40°, compared with 1.04° of the sprayer chassis. Experimental results show that the active suspension control system can effectively reduce the effect of ground excitation disturbance on the application process, and has good tracking performance for low frequency terrain change. Keywords: boom sprayer, active suspension, electro-hydraulic servo system, six DOF motion simulator, signal process, motion control DOI: 10.25165/j.ijabe.20191204.4648 Citation: Cui L F, Xue X Y, Le F X, Mao H P, Ding S M. Design and experiment of electro hydraulic active suspension for controlling the rolling motion of spray boom. Int J Agric & Biol Eng, 2019; 12(4): 72–81.

Proportional + integral + derivative control of nonlinear full-car electrohydraulic suspensions using global and evolutionary optimization techniques

Resolving the trade-offs between suspension travel, ride comfort, road holding, vehicle handling and power consumption is the primary challenge in the design of active vehicle suspension system. Multi-loop proportional + integral + derivative controllers’ gains tuning with global and evolutionary optimization techniques is proposed to realize the best compromise between these conflicting criteria for a nonlinear full-car electrohydraulic active vehicle suspension system. Global and evolutionary optimization methods adopted include: controlled random search, differential evolution, particle swarm optimization, modified particle swarm optimization and modified controlled random search. The most improved performance was achieved with the differential evolution algorithm. The modified particle swarm optimization and modified controlled random search algorithms performed better than their predecessors, with modified controlled random search performing better than modified particle swarm optimization in all aspects of performance investigated both in time and frequency domain analyses.

Design and experiment of electro hydraulic active suspension for controlling the rolling motion of spray boom

Design and experiment of electro hydraulic active suspension for controlling the rolling motion of spray boom

Parametric numerical study of electrohydraulic active suspension performance against passive suspension

A parametric numerical study for an active electro-hydraulic and passive automotive quarter-car suspensions is implemented. Performance comparison is carried out numerically using SIMULINK's Simscape library. Road, vehicle and suspension parameters were varied and their effect were shown. Those parameters are the bump’s shape, amplitude and frequency, sprung mass, spring stiffness and damping coefficient. The active control is proportional-integral-derivative. This technique is most suitable as it shows how varied parameters affect the system for the same control technique. Vibrational analysis was performed on the system. The details of the developed system with the analytical results are presented. The active suspension’s performance was always superior to the passive. The active performance decreases slightly while increasing the road input frequency and amplitude. Also its performance is found to be undependable on the sprung mass thus having high load carrying capacity. Changing spring stiffness and damping coefficients didn’t affect the active performance much. It is also concluded that the spring and damper in parallel to the hydraulic suspension don’t affect the active performance but only useful as failsafe option.

Electrohydraulic Active Suspension Fuzzy-Neural Based Control System

A design of a new controller via a combination of fuzzy controller and artificial neural network (ANN) force tracking solution for a full vehicle suspension system with nonlinear electrohydraulic actuator dynamics is proposed. The comparison between the new Fuzzy-ANN force tracking controller designed with passive suspension system and PID-ANN controller previously developed is presented. Simulations and results obtained show that the Fuzzy-ANN combined controller can improve the stability problems caused by disturbances and road conditions, providing a superior passenger comfort.

Dynamic neural network-based feedback linearization control of full-car suspensions using PSO

This paper proposes a nonlinear control approach using dynamic neural network-based input–output feedback linearization to resolve the inherent conflicting performance criteria for a full-car nonlinear electrohydraulic active vehicle suspension system. Particle swarm optimization is applied both for the dynamic neural network models’ trainings and the computation of the controllers’ parameters. The intelligent control scheme outperformed the passive vehicle suspension system and the benchmark particle swarm-optimized proportional+integral+derivative controller. Effectiveness and robustness of the proposed controller are demonstrated through simulations both in time- and frequency-domains.

Real‐time hybrid control of electrohydraulic active suspension

SummaryElectrohydraulic actuators are an attractive choice for active suspension, because these systems provide a high power‐to‐weight ratio. However, their dynamics are highly nonlinear. In addition, the use of one simple controller for both position and force is complicated, because there is a compromise between them in the case of active suspension. Most existing controllers do not efficiently fulfill the requirements, because only one state variable is considered.In this paper, we address these problems by developing a new hybrid controller for both position and force and implementing it in a real‐time test bench. Our goal is to control the vertical position of the passenger seat while tracking the force transmitted to passengers and keeping it within tolerable and comfortable limits. Therefore, the proposed controller is a combination of two controllers. Its flexible structure redirects the control signal to control the proper controlled state variable. The real‐time results of the newly designed hybrid controller are compared with those obtained using a classical proportional integral derivative controller, because this is the most widely used controller in the industry. As expected, the proposed controller demonstrates better performance in real‐time operation. Copyright © 2017 John Wiley & Sons, Ltd.

A universal suspension test rig for electrohydraulic active and passive automotive suspension system

A fully active electro-hydraulic and passive automotive quarter car suspensions with their experimental test-rigs are designed and implemented. Investigation of the active performance compared against the passive is performed experimentally and numerically utilizing SIMULINK's Simscape library. Both systems are modeled as single-degree-of-freedom in order to simplify the validation process. Economic considerations were considered during the rig's implementation. The rig consists of two identical platforms fixed side by side allowing testing two independent suspensions simultaneously. Position sensors for sprung and unsprung masses on both platforms are installed. The road input is introduced by a cam and a roller follower mechanism driven by 1.12kW single phase induction motor with speed reduction assembly. The active hydraulic cylinder was the most viable choice due to its high power-to-weight ratio. The active control is of the proportional-integral-differential (PID) type. Though this technique is quite simple and not new, yet the emphasis of this paper is the engineering, design and implementation of the experimental setup and controller. A successful validation process is performed. Ride comfort significantly improved with active suspension, as shown by the results; 24.8% sprung mass vibration attenuation is achieved. The details of the developed system with the analytical and experimental results are presented.

T-S Fuzzy Model Based H-Infinity Control for 7-DoF Automobile Electrohydraulic Active Suspension System

This paper presents a double loop controller for a 7-DoF automobile electrohydraulic active suspension via T-S fuzzy modelling technique. The outer loop controller employs a modified H-infinity feedback control based on a T-S fuzzy model to provide the actuation force needed to ensure better riding comfort and handling stability. The resulting optimizing problem is transformed into a linear matrix inequalities solution issue associated with stability analysis, suspension stroke limit, and force constraints. Integrating these via parallel distributed compensation method, the feedback gains are derived to render the suspension performance dependent on the perturbation size and improve the efficiency of active suspensions. Adaptive Robust Control (ARC) is then adopted in the inner loop design to deal with uncertain nonlinearities and improve tracking accuracy. The validity of improvements attained from this controller is demonstrated by comparing with conventional Backstepping control and a passive suspension on a 7-DoF simulation example. It is shown that the T-S fuzzy model based controller can achieve favourable suspension performance and energy conservation under both mild and malevolent road inputs.

Modelling and Control of an Electro-Hydraulic Active Suspension System

Active suspension systems ease the conflict between comfort and handling. This requires the use of suitable actuators that in turn need to be efficiently controlled. This paper proposes a model-based control approach for a nonlinear suspension actuator. Firstly the concept is derived in the linear framework in order to simplify the synthesis and analysis phase. There a linear model of the actuator is proposed and discussed. Further, this design phase includes a comparison between model-free PID controllers and a newly proposed two-degree-of-freedom controller which allows one to shape reference and disturbance responses separately. Subsequently, the two-degree-of-freedom controller, which proves to be superior, is adapted to the nonlinear framework by considering a linear parameter varying representation of the nonlinear plant. Finally, the nonlinear controller is implemented in a test car confirming the concept applicability to real hardware.

Interlaced Backstepping and Integrator Forwarding for Nonlinear Control of an Electrohydraulic Active Suspension

Passengers' comfort in long road trips is of crucial importance1 as a result, active suspension control became a vital subject in recent researches. This paper studies the control of an electrohydraulic active suspension, based on a combination of backstepping and integrator forwarding. Our goal is to control and reduce the car's vertical motion and keep it to zero. The active suspension model is highly nonlinear and nondifferentiable due to the hydraulic components, especially the servovalve and the hydraulic actuator whose chambers' volume varies during extension and retraction. Therefore, a powerful control strategy is required. In such cases, Lyapunov-based control strategies are the most suitable for offering a lot of maneuverability in building an analytical control signal. The mathematical model of an electrohydraulic active suspension can be classified among interlaced systems. This means that the state space model is a sequence of feedback and feedforward equations. Therefore, interlaced backstepping and integrator forwarding is an optimal control strategy to stabilize this class of systems, particularly electrohydraulic active suspension. Afterwards, we will introduce and define this constructive control method and its basis. The foremost advantage of this interlaced strategy is that, unlike others, it leaves no internal dynamic. This is a great relief in control issues, because an unstable internal dynamic will destabilize the whole system whatever control method is being used. As will be demonstrated, the interlaced backstepping and integrator forwarding is an outstanding control strategy to compensate the effect of chaotic roads on the stability of cars. The results are compared with a classic Proportional-Integral-Derivative regulator and a sliding mode controller, to show that the proposed controller outperforms a range of existing controllers for a range of perturbation signals.

229 電動アクティブサスペンションのエネルギ回生と振動の最適制御に関する基礎的検討

229 電動アクティブサスペンションのエネルギ回生と振動の最適制御に関する基礎的検討

The application of a programmable servo controller to state control of an electrohydraulic active suspension

Fully active electrohydraulic control of a 1/4 car test rig is considered from both a modelling and experimental point of view. Both pole assignment (PA) and linear quadratic control (LQC) techniques are used to design the state feedback gains with a view to achieving an optimum body acceleration characteristic, based on a validated linearized mathematical model. Computer simulation of the complete system suggests that the LQ control design approach gives the better performance characteristic. An industrial programmable servo controller (PSC) is implemented to drive two servo valves, one used for the road input actuator and the other used for the active control actuator. Programmable features are introduced, such as gain scheduling and state gain switching to achieve improved control. It is shown that although body displacement compensation is naturally achieved for road input changes, the global optimum design for acceleration transmissibility could not be achieved, due to practical limitations caused by the predicted low transducer gain between wheel and body. A further feature of the programmable controller approach was the ability to change state feedback gains during operation. This was found necessary to move the suspension from its initial rest position to its operating position. However, an improved performance in body acceleration amplitude control was still possible compared with the optimum passive suspension theoretical predictions.

Hybrid fuzzy control for electro-hydraulic active damping suspension

A new control scheme, the hybrid fuzzy control method, for active damping suspension system is presented. The scheme is the result of effective combination of the statistical optimal control method based on the statistical property of suspension system, with the bang-bang control method based on the real-time characteristics of suspension system. Computer simulations are performed to compare the effectiveness of hybrid fuzzy control scheme with that of optimal damping control, bang-bang control, and passive suspension. It takes the effects of time-variant factors into full account. The superiority of the proposed hybrid fuzzy control scheme for active damping suspension to the passive suspension is verified in the experiment study.