Fuzzy and adaptive fuzzy control for the automobiles’ active suspension system

Two typical criteria for good vehicle suspension performance are their ability to provide good road handling and increased passenger comfort. The main disturbance affecting these two criteria is terrain irregularities. Active suspension control systems reduce these undesirable effects by isolating car body motion from vibrations at the wheels. This paper describes fuzzy and adaptive fuzzy control (AFC) schemes for the automobile active suspension system (ASS). The design objective is to provide smooth vertical motion so as to achieve the road holding and riding comfort over a wide range of road profiles. The efficacy of the proposed control schemes is demonstrated via simulations. With respect to the optimal linear quadratic regulator (LQR), it is shown that superior results have been achieved by the AFC.     

State observer-based sliding mode control for semi-active hydro-pneumatic suspension

This paper proposes an improved virtual reference model for semi-active suspension to coordinate the vehicle ride comfort and handling stability. The reference model combines the virtues of sky-hook with ground-hook control logic, and the hybrid coefficient is tuned according to the longitudinal and lateral acceleration so as to improve the vehicle stability especially in high-speed condition. Suspension state observer based on unscented Kalman filter is designed. A sliding mode controller (SMC) is developed to track the states of the reference model. The stability of the SMC strategy is proven by means of Lyapunov function taking into account the nonlinear damper characteristics and sprung mass variation of the vehicle. Finally, the performance of the controller is demonstrated under three typical working conditions: the random road excitation, speed bump road and sharp acceleration and braking. The simulation results indicated that, compared with the traditional passive suspension, the proposed control algorithm can offer a better coordination between vehicle ride comfort and handling stability. This approach provides a viable alternative to costlier active suspension control systems for commercial vehicles.     

基于模糊算法的车辆半主动悬架控制

以汽车二自由度悬架系统为研究对象,针对半主动悬架系统,提出以车身加速度为控制目的的模糊控制策略。以白噪声随机响应谱作为B级路面的激励输入,对被动悬架和半主动悬架系统进行仿真研究。仿真后的被动悬架与半主动悬架对结果表明,所提出的模糊控制策略有效的降低了悬架系统被击穿的可能性,提高了汽车乘坐的舒适性。     

Development of Preview Active Suspension Control System and Performance Limit Analysis by Trajectory Optimization

The main role of the suspension system is to achieve ride comfort by reducing vibrations generated by the road roughness. The active damper is getting much attention due to its reduced cost and ability to enhance ride comfort especially when the road ahead is measurable by an environment sensor. In this study a preview active suspension control system was developed in order to improve ride comfort when the vehicle is passing over a speed bump. The control system consists of a feedback controller based on the skyhook logic and a feedforward controller for canceling out the road disturbance. The performance limit for the active suspension control system was computed via trajectory optimization to provide a measure against which to compare and validate the performance of the developed controller. The simulation results indicated that the controller of this study could enhance ride comfort significantly over the active suspension control system employing only the skyhook feedback control logic. Also the developed controller, by displaying similar control pattern as the trajectory optimization during significant time portions, proved that its control policy is legitimate.     

半主动空气悬架模糊控制的仿真研究

对采用模糊控制的汽车半主动空气悬架系统进行了仿真研究。建立了1／4车辆二自由度动力学模型并以其为仿真对象,设计了模糊控制器,以B级路面作为随机输入,进行了计算机仿真分析。仿真结果表明,在采用模糊控制方法后．车辆悬架可以很好地降低簧载质量的垂直加速度,从而使车辆行驶的平顺性和乘坐舒适性得到了提高。     

基于半主动自适应悬架系统的整车道路友好性研究

为了提高车辆的道路友好性与平顺性,设计了以磁流变减振器为控制对象的整车自适应模糊控制半主动悬架系统。在试验测试和理论分析的基础上,建立了基于磁流变减振器的整车半主动悬架模型及其状态方程,并用该模型对自适应模糊控制方法进行了研究。模型的输入采用B级和C级路面谱;道路友好性评价指标采用动载荷系数和动载荷应力因子;使用MATLAB/Simulink建立基于2个自适应模块的模糊控制器控制系统,模糊控制器的输入均采用车身与车桥的相对速度和相对加速度。仿真结果表明:与被动悬架相比,在B级和C级路面、不同速度下,半主动自适应悬架动载荷系数均降低30%左右,动载荷应力因子均降低40%以上,同时也提高了车辆的运行平顺性和稳定性。     

汽车主动悬架自调整模糊控制试验

以汽车操纵稳定性及行驶平顺性为控制目标,提出一种在线可调整的模糊控制算法,其模糊控制规则表可以用解析的方法进行计算。针对简化的汽车模型,为控制悬架系统的振动设计了自调整模糊控制器。与自适应控制主动悬架系统相比较,在两自由度悬架系统试验台架上进行了对比试验研究,结果表明该算法对汽车的振动控制具有明显效果,进一步说明提出的算法对汽车悬架系统的振动控制具有较好的适应性。     

Level and attitude control of the active suspension system with integral and derivative action

A 7-DOF full-car model with optimal active control suspension is utilized to evaluate the vehicle dynamic performances which are achieved through proposed controllers. The optimal controller, which includes the integral action for the suspension deflection, considerably improves the attitude control of a vehicle because the rolling and pitching motion in cornering and braking maneuvers are reduced, respectively. In the viewpoint of level control, the integral control acting on the suspension deflection results in the zero steady-state deflection in response to static body forces and ramp road input. The dynamic characteristics of the suspension control system are evaluated in terms of time domain and frequency domain. The simulations in the time domain demonstrate the advantages of the active suspension system obtained by penalizing the integral and derivative of suspension deflections and the derivative of roll and pitch angles in the performance index. The frequency characteristic curves obtained by simulations regarding integral action or derivative action show the increase of both ride comfort and road-holding performances by maximizing the use of suspension deflections. The potential of derivative control is shown by the performances of the car traveling over a bump and braking.     

Level and attitude control of the active suspension system with integral and derivative action

A 7-DOF full-car model with optimal active control suspension is utilized to evaluate the vehicle dynamic performances which are achieved through proposed controllers. The optimal controller, which includes the integral action for the suspension deflection, considerably improves the attitude control of a vehicle because the rolling and pitching motion in cornering and braking maneuvers are reduced, respectively. In the viewpoint of level control, the integral control acting on the suspension deflection results in the zero steady-state deflection in response to static body forces and ramp road input. The dynamic characteristics of the suspension control system are evaluated in terms of time domain and frequency domain. The simulations in the time domain demonstrate the advantages of the active suspension system obtained by penalizing the integral and derivative of suspension deflections and the derivative of roll and pitch angles in the performance index. The frequency characteristic curves obtained by simulations regarding integral action or derivative action show the increase of both ride comfort and road-holding performances by maximizing the use of suspension deflections. The potential of derivative control is shown by the performances of the car traveling over a bump and braking.     

基于行驶舒适性的路桥过渡段差异沉降控制标准

从人车路相互作用出发,建立了人车路系统振动方程和路桥过渡段路面不平整模型,并通过编制的RCBP程序分析了车辆行驶舒适性的影响因素,最后确定了基于行驶舒适性的路桥过渡段差异沉降控制标准。结果不仅可以用于路桥过渡段差异沉降控制标准的相关规范,也可用于一般路基差异沉降标准的制定,对桥头跳车问题的处治和路桥过渡段路面的养护维修提供了科学决策依据。     

空气悬架系统模糊控制仿真分析

对汽车空气悬架系统的模糊控制方法进行了仿真研究。以1／4车辆模型为仿真对象，建立模糊控制器，并模拟B级路面为随机输入，对模型进行了计算机仿真。结果表明，在引入模糊控制方法后，车辆的行驶平顺性得到了有效改善。另外，当系统模型的结构参数发生改变时，该控制器表现出良好的鲁棒性。     

汽车主动悬架的单神经元自适应控制

在1/4汽车动力学模型的基础上,设计了汽车主动悬架的自适应神经元控制器。以车辆的行驶平顺性为主要控制目标,车身垂直加速度、悬架动挠度、车轮动位移为具体评价参数,研究了系统在随机路面激励条件下的时域响应,计算了振动响应的均方根值,考察了在变参数条件下控制器的鲁棒性。仿真结果表明,该控制器能有效改善车辆的综合性能,尤其是平顺性和舒适性,并且具有较好的鲁棒性,对模型参数的变化有一定的适应性。     

基于T-S模型的主动悬架保性能控制研究

建立了1/2车4自由度主动悬架的T-S模糊模型,提出了基于该模型的模糊保性能控制方案,并且针对含有参数不确定性的主动悬架系统进行了仿真。结果表明该方法能够取得较满意的控制效果,也证明了主动悬架系统在减少振动、提高汽车平顺性方面要优于被动悬架。     

半主动悬架模糊控制仿真

为缓和路面传递给车身的冲击,改善汽车行驶的平顺性和操作稳定性,文章建立了二自由度1／4车体半主动悬架非线性动力学模型,利用MATLAB模糊逻辑控制工具箱设计半主动悬架的模糊控制器,通过运用MATLAB／SIMULINK,对悬架系统进行了仿真分析。结果表明,该控制方法能有效地降低车身垂直加速度、悬架的动挠度和车轮动载荷,提高了汽车的平顺性和操纵稳定性。     

磁流变半主动悬架研究及实车试验分析

针对车辆半主动悬架系统的整车协调控制,通过悬架动力学模型分析了耦合量的影响,提出了一种主从控制方法。基于自行研制的并联常通孔式磁流变减振器和控制系统开展了实车道路试验。在越野路行驶时,驾驶员坐垫处的加权加速度降低了13.8%~42.6%,车身俯仰角速度降低了21.1%~53.7%;蛇行试验中车身侧倾角速度、角度分别平均降低了65%和38.5%;变道试验中车身侧倾角速度、角度分别平均下降65%和51%。综上所述,研制的磁流变悬架系统显著地提升了车辆的乘坐舒适性、操纵稳定性和行驶安全性。     

汽车半主动悬架性能的联合仿真分析

为分析半主动悬架对汽车性能的影响,文章对半主动悬架的性能进行了仿真分析。首先在ADAMS／View开发环境中建立1/4汽车悬架模型;然后基于MATLAB／Simulink设置模糊控制规则,对半主动悬架进行模糊控制,并模拟出随机路面输入信号;最后利用ADAMS／Control模块将ADAMS和MATLAB／Simulink悬架模型联合起来进行仿真,与被动悬架进行了对比分析．可以看出,模糊控制下的半主动悬架舒适性更高,行驶安全性和操纵稳定性更好。联合仿真结果表明,半主动悬架的舒适性和平顺性均优于被动悬架。     

Extended Ground-Hook - New Concept of Semi-Active Control of Truck's Suspension

This paper deals with the novel control concept, so called ground-hook for active and mainly semi-active suspension of vehicles with the ultimate objective to minimize the tyre-road forces and thus the road damage. The basic ground-hook concept is extended to the several variants which enable to decrease criteria of road damage as well as to increase driver's comfort for a broad range of road unevennesses. Parameters of control law are determined by the parameter optimization for generally nonlinear model. The influence and interaction of the damping rate limits and time constants of variable shock absorbers are also taken into account. The influence of implementation of more complicated truck models is also discussed.     

电液主动悬架滤波输出反馈控制器的设计及仿真实现

基于1／2车辆模型和非线性电液作动器，提出并详细设计了主动悬架滤波输出反馈控制器。整个主动悬架系统分解为内、外两个回路，外回路采用滤波输出反馈控制，大幅度衰减了车辆在高低频范围内的起伏和俯仰运动，提高了车辆的乘坐舒适性。内回路基于非线性作动器模型，采用传统的PI控制器，较好地跟踪输出了控制系统需要的作用力。此外，还对作动系统的摩擦力进行了详细建模。频域和时域仿真结果演示了主动悬架的良好性能并验证了结论。     

铰接式自卸车橡胶弹簧悬架系统试验研究

采用模拟随机输入路面谱激励室内台架试验的方法,对装有新型橡胶弹簧悬架系统的某型号铰接式自卸车进行台架试验研究,以评价橡胶弹簧悬架系统的减振性能和整车行驶平顺性。试验结果表明由于橡胶弹簧悬架系统某些参数匹配不合理导致该车行驶平顺性很不理想,通过优化悬架及座椅的刚度和阻尼参数,可提高整车行驶平顺性,并给出了座椅弹簧的优化结果。     

Performance evaluation and parameter sensitivity of energy-harvesting shock absorbers on different vehicles

Traditional shock absorbers provide favourable ride comfort and road handling by dissipating the suspension vibration energy into heat waste. In order to harvest this dissipated energy and improve the vehicle fuel efficiency, many energy-harvesting shock absorbers (EHSAs) have been proposed in recent years. Among them, two types of EHSAs have attracted much attention. One is a traditional EHSA which converts the oscillatory vibration into bidirectional rotation using rack-pinion, ball-screw or other mechanisms. The other EHSA is equipped with a mechanical motion rectifier (MMR) that transforms the bidirectional vibration into unidirectional rotation. Hereinafter, they are referred to as NonMMR-EHSA and MMR-EHSA, respectively. This paper compares their performances with the corresponding traditional shock absorber by using closed-form analysis and numerical simulations on various types of vehicles, including passenger cars, buses and trucks. Results suggest that MMR-EHSA provides better ride performances than NonMMR-EHSA, and that MMR-EHSA is able to improve both the ride comfort and road handling simultaneously over the traditional shock absorber when installed on light-damped, heavy-duty vehicles. Additionally, the optimal parameters of MMR-EHSA are obtained for ride comfort. The optimal solutions (‘Pareto-optimal solutions’) are also obtained by considering the trade-off between ride comfort and road handling.