具有执行器容错的汽车主动悬架系统有限频率H∞控制

本文研究了一类具有执行器容错的主动悬架系统有限频率H_∞控制问题.运用广义的Kalman-Yakubovich-Popov(KYP)引理,设计了有限频率H_∞控制器.该控制器不仅能够最大程度地减少路面在4～8 Hz范围内对乘客的影响,还能够保证汽车的悬架行程和车轮的动静载之比在它们允许的范围内.因此所设计的有限频率H_∞控制器不仅能够保证汽车驾驶的舒适性还能够保证汽车驾驶的安全性.为了解决系统状态不完全可测的问题,本文采用了动态输出反馈控制器策略.除此之外,在控制器的设计过程中还考虑了主动悬架系统的参数不确定性以及执行器随机故障的现象.最后,本文基于四分之一汽车主动悬架系统验证了控制器的有效性.     

Sliding mode neural network inference fuzzy logic control foractive suspension systems

In the automotive industry, suspension systems are designed to provide desirable vehicle ride and handling properties. This paper presents the development of a robust intelligent nonlinear controller for active suspension systems based on a comprehensive and realistic nonlinear model. The inherent complex nonlinear system model's structure, and the presence of parameter uncertainties, have increased the difficulties of applying conventional linear and nonlinear control techniques. Recently, the combination of sliding mode, fuzzy logic, and neural network methodologies has emerged as a promising technique for dealing with complex uncertain systems. In this paper, a sliding mode neural network inference fuzzy logic controller is designed for automotive suspension systems in order to enhance the ride and comfort. Extensive simulations are performed on a quarter-car model, and the results show that the proposed controller outperforms existing conventional controllers with regard to body acceleration, suspension deflection, and tire deflection     

Robust oscillation control of wheeled mobile robots

In cases where a wheeled mobile robot runs fast on a rough surface, the sensors mounted on the robot’s body may be destroyed due to the body acceleration and oscillation. In this article, we propose a new scheme to reduce the body acceleration at any specified location for mobile robots with the actuators set on the wheel axes. To achieve this, a combined ideal robot model is designed. In the combined ideal robot model, the location where the acceleration performance is at its best can easily be moved by setting only two design parameters. Next, a robust model tracking controller is developed so that the behavior of an actual mobile robot can track the combined ideal robot model. The developed controller has the following useful properties. (1) The body acceleration at any specified location can easily be improved. (2) The developed controller has good robustness for uncertainties in robot mass, pitch and roll moment of inertia of the robot’s body, and the position of the center of gravity.     

An investigation into vehicle rollover prevention by coordinated control of active anti-roll bar and electronic stability program

This paper presents a method for designing a controller that uses an active anti-roll bar (AARB) and an electronic stability program (ESP) for rollover prevention. ESP with longitudinal speed control (LSC) can carry out active braking to reduce vehicle speed and lateral acceleration to prevent a rollover. To enhance the rollover prevention capability of the ESP, an AARB is adopted. The controller for the AARB was designed based on linear quadratic (LQ) static output feedback (SOF) control methodology, which attenuates the effect of lateral acceleration on the roll angle and roll rate by control of the suspension stroke and the tire deflection of the vehicle. Although this AARB significantly increases ride comfort and rollover prevention, it has a drawback — the vehicle loses its maneuverability. Therefore, the ESP with LSC is used to overcome this drawback. Simulations showed that the proposed method was effective in preventing a rollover.     

A New SSUKF Observer for Sliding Mode Force Tracking H∞ Control of Electrohydraulic Active Suspension

Compared to passive and semi‐active suspensions, active suspensions have the capacity to overcome the tradeoff design of vehicle ride comfort and handling performance. In this paper, a new control system with modified spherical simplex UKF (SSUKF) observer and sliding mode force tracker is proposed for electrohydraulic active suspensions. The estimated states obtained from the SSUKF observer are used to derive the mode energy of body motion and design the target demanded forces for suspension actuators. A sliding mode controller is presented to drive electrohydraulic actuators to track the demanded forces. Based on a robust H∞ control method, a new control strategy depending on body mode energy is proposed to restrict body motion. The performance comparisons between passive and active suspensions under three typical excitations are presented, and the obtained results indicate that the proposed control system can significantly depress body motion and decrease the mode energy to improve ride comfort and also effectively enhance the road hold abilities.     

Novel Optimal Design Approach for Output‐Feedback H∞ Control of Vehicle Active Seat‐Suspension System

In this paper, the output‐feedback control problem of a vehicle active seat‐suspension system is investigated. A novel optimal design approach for an output‐feedback H_∞ controller is proposed. The main objective of the controller is to minimize the seat vertical acceleration to improve vehicle ride comfort. First, the human body and the seat are considered in the modeling of a vehicle active suspension system, which makes the model more precise. Other constraints, such as tire deflection, suspension deflection and actuator saturation, are also considered. Then the output‐feedback control strategy is adopted since some state variables, such as body acceleration and body deflection, are unavailable. A concise and effective approach for an output‐feedback H_∞ optimal control is presented. The desired controller is obtained by solving the corresponding linear matrix inequalities (LMIs) and by the calculation of equations proposed in this paper. Finally, a numerical example is presented to show the effectiveness and advantages of the proposed controller design approach.     

多轴越野车辆的行驶平顺性

以多轴越野车为研究对象,应用机械系统动力学仿真分析软件MSC Adams建立一、二、三桥悬架,轮胎及整车的多体系统模型. 进行整车脉冲输入及随机输入平顺性仿真分析,实现了在车辆设计阶段对其进行平顺性预测与分析的目标.     

A novel integrated control framework of AFS,ASS, and DYC based on ideal roll angle to improve vehicle stability

The current research on vehicle stability control mainly focuses on following the ideal yaw rate and sideslip angle, without considering the potential of ideal roll angle in improving the vehicle stability. In addition, the mutation of tire-road friction coefficient promotes a great challenge to the stability control. To improve the vehicle stability, in this study, firstly, the three-dimensional stability region of “lateral speed-yaw rate-roll angle” was studied, and a method to determine the ideal roll angle was proposed. Secondly, a novel integrated control framework of AFS, ASS, and DYC based on ideal roll angle was proposed to actively control the front tire slip angles, suspension forces, and motor torques: In the upper-level controller, model predictive control and tire force distribution algorithm were used to obtain the optimal four-tire longitudinal forces, front tire lateral forces and additional roll moment under constraints; In the lower-level controller, the upper virtual target was realized by the optimal allocation algorithm of actuators and the tire slip controller. Finally, the proposed control framework was verified on the varied-µ road. The results indicated that compared with the two existing control strategies, the proposed framework can significantly improve the vehicle following performance and stability.     

刚柔耦合重型汽车建模及通过连续减速带的平顺性分析

建立了考虑车架柔性的刚柔耦合重型汽车整车模型,通过与刚性车对比,验证了所建刚柔耦合车辆模型的正确性.依据实际需求建立了三组连续减速带模型,以车身垂向加速度和各轮垂向轮胎力为评价指标,分析车辆行驶速度、减速带高度和宽度对汽车行驶平顺性的影响.研究表明,减速带的高度与车身垂向加速度和垂向轮胎力成正比,减速带宽度与车身垂向加速度和垂向轮胎力成反比,对于限速60 km/h的道路,宽度为600 mm,高度为8 mm的减速带能起到良好的限速效果,同时还能保证车辆行驶的平顺性.     

兼顾平顺性与车高调节的重型车空气悬架控制

空气悬架由于质量轻、刚度以及高度可调等优点在重型车中得到了广泛的应用.空气悬架可以实现重型车的两项重要功能:平顺性保证以及车身高度调节,但是空气悬架的平顺性以及车身高度调节均通过空气弹簧气压腔的气压改变来实现,因此二者是彼此制约和冲突的.然而,目前对空气悬架车高调节的研究追求控制的精确性与稳定性而忽略了平顺性,而对平顺性的研究又几乎不考虑车高变化造成的影响.基于上述动机,本文提出了兼顾平顺性的空气悬架重型车车高调节鲁棒控制方法,实现了平顺性保障下的车高调节曲线精确跟踪控制,提升了重型车空气悬架系统的整体性能.实车参数仿真验证了所提出方法在平顺性与车高调节两项指标中的优越性.     

Potential of low bandwidth active suspension control with continuously variable damper

In this paper, the performance potential of a new hardware combination for active suspension systems is presented. It consists of a low bandwidth actuator and a continuously variable damper, a setup that is shown to be competitive to high bandwidth active suspension systems especially if energy, cost and implementability aspects are taken into account. This is achieved by an iterative optimization procedure for the damping ratio and the weights of time-invariant LQR controllers for active quarter-car models. The results of the procedure are obtained by simulations employing a road disturbance model that is validated using measurements of a real highway profile. The achievable performance of the new hardware combination is compared to passive and high bandwidth active suspension systems by means of carpet plots. Based on the comparison results, it is shown that ride comfort can be significantly increased while satisfying given constraints for ride safety (maximum tire deflections) and suspension travel.     

Vibration damping of a flexible car body structure using piezo-stack actuators

Active vibration damping of a railway car body is accomplished by actuator forces acting directly on the flexible car body structure. In this work piezo-stack actuators mounted in consoles are utilized to introduce bending moments into the flexible structure, thus achieving a significant increase in ride comfort. For a heavy metro vehicle the complete design of the active vibration damping system is presented. Analytic modeling, system identification, and robust controller design are presented. The excellent performance of the proposed method is documented by both extensive experimental results and co-simulation studies.     

Lane-keeping assistance control algorithm using differential braking to prevent unintended lane departures

This paper describes a hierarchical lane keeping assistance control algorithm for a vehicle. The proposed control strategy consists of a supervisor, an upper-level controller and a lower-level controller. The supervisor determines whether lane departure is intended or not, and whether the proposed algorithm is activated or not. To detect driver′s lane change intention, the steering behavior index has been developed incorporating vehicle speed and road curvature. To validate the detection performance on the lane change intention, full-scale simulator tests on a virtual test track (VTT) are conducted under various driving situations. The upper-level controller is designed to compute the desired yaw rate for the lane departure prevention, and for the guidance with ride comfort. The lower-level controller is designed to compute the desired yaw moment in order to track the desired yaw rate, and to distribute it into each tire′s braking force in order to track the desired yaw moment. The control allocation method is adopted to distribute braking forces under the actuator’s control input limitation. The proposed lane keeping assistance control algorithm is evaluated with human driver model-in-the-loop simulation and experiments on a real vehicle.     

Vehicle Dynamics Modeling and Electronic Stability Program/ Active Front Steering Sliding Mode Integrated Control

Chassis integrated control can significantly improve vehicle handling stability and comfort. Because of the complexity of the problem, it has attracted significant research attention. We built a vehicle nonlinear dynamic model with multi‐degree freedom, including body movement, wheel movement, and electronically controlled hydraulic power steering system. We compared the magic formula tire model, Dugoff tire model, brush tire model, and LuGre dynamic friction tire model and steady model. The precision of the model was verified by a comparison between simulation results and the real vehicle test results. Then, based on the vehicle dynamics model, an AFS (active front steering) controller was designed based on sliding mode variable structure control, and an AFS and ESP (electronic stability program) integrated coordination controller was proposed. Finally, based on the nonlinear tire model and multi‐DOF (degree of freedom) vehicle model, sinusoidal and step steering angle input simulation analysis was proposed on different road friction coefficients. The results show that the vehicle has better response characteristics with coordinated control strategy when compared with AFS and ESP only control. The evidence suggests that the proposed integrated control system in this paper can improve vehicle stability and safety.     

基于模型预测控制的电动车辆队列控制研究

针对车辆队列建模时参数不确定导致控制存在误差的问题,以及队列中跟随车辆稳定性问题,分析车辆纵向动力学,设计一个鲁棒MPC控制器和滑移率控制器来提高队列车辆的控制精度和稳定性.首先对纵向MPC控制器进行改进,提高车辆队列控制精度；同时为防止跟随车辆的轮胎打滑,设计一个MPC滑移率控制器对跟随车辆的轮胎滑移率进行控制约束,保证了跟随车辆的纵向稳定性.最后,进行仿真实验验证其有效性.仿真实验结果表明,与传统的LQR、MPC控制器相比,改进的鲁棒MPC纵向控制器控制精度更高,同时MPC滑移率控制器可防止跟随车辆的轮胎打滑,保证了跟随车辆的纵向稳定性.     

Pushing the limits: From lanekeeping to autonomous racing

The success of Electronic Stability Control (ESC) has demonstrated the potential life-saving benefits of vehicle control systems. Lanekeeping presents an obvious next step in vehicle control, but the performance of such systems must be guaranteed before lanekeeping can be viewed as a safety feature. This paper demonstrates that simple lookahead control schemes for lanekeeping are provably robust even at the limits of tire adhesion. By responding to the heading error relative to the desired path, these schemes provide the countersteer behavior necessary to compensate for rear tire saturation and stabilize the vehicle. Using a Lyapunov-based analysis, vehicle stability can be proven even with a highly saturated tire. Taking this a step further by developing a desired path based on the racing line, this lookahead controller can be coupled with longitudinal control based on path position and wheel slip to create an autonomous racecar. The performance of this algorithm shows the potential for lanekeeping control that can truly assist even the best drivers.     

主被动一体悬架构型的多目标粒子群最优控制

为了解决轮毂电机电动汽车中轮毂电机导致的振动负效应问题,提出了将动态减振与主动悬架结合的悬架新构型方案.针对新构型中结构及控制参数复杂的特点,建立了能够表征平顺性、操稳性以及悬架作动效率的11自由度整车动力学模型.设计基于新构型的多目标粒子群线性二次最优(MOPSO–LQR)控制器.对模型进行仿真分析,仿真结果表明,新构型方案能够实现车辆平顺性、操稳性以及悬架效率的全局最优,对比传统轮毂电机悬架构型方案,在解决轮毂电机振动负效应问题上有良好的效果.     

汽车脉冲输入平顺性的仿真分析

该文讨论了运用虚拟样机技术 ,进行汽车脉冲输入平顺性仿真分析的方法 ,针对本校研制的电动牵引车建立了包括悬架、车体和人 -椅系统在内的多体系统模型 ,并通过建立轮胎的UA解析模型和三维路面模型来计算轮胎与地面的相互作用。通过仿真试验 ,对该车的平顺性能进行了评价 ,分析了悬架和座椅参数对该车平顺性的影响 ,从而实现了在该车的设计阶段 ,对其平顺性进行预测及分析的目的。     

基于自适应遗传算法的半主动悬架模糊控制研究

模糊规则的正确选择是半主动悬架模糊控制器设计的关键和难点,本文提出一种自适应地选择交叉概率和变异概率的遗传算法,以车身垂直加速度均方根值为优化目标,对汽车半主动悬架模糊控制规则进行优化,以达到提高半主动悬架模糊控制器的控制效果,改善汽车行驶平顺性的目的。为了证明该优化方法的可行性,将该自适应遗传算法优化的模糊控制器对汽车半主动悬架进行控制,并建立Matlab文本与Simulink相结合的仿真模型。仿真结果表明：优化后的半主动悬架车身垂直加速度均方根值减小,汽车行驶的平顺性得到了提高。