Control algorithm for vehicle height adjustable system of hydro-pneumatic suspension based on LuGre model

In order to control the vehicle body position precisely, 1/4 nonlinear mathematical model of hydro-pneumatic suspension is established, and the influence of the frictional force in a hydraulic cylinder is analyzed. The friction characteristics are described based on the LuGre model when the piston of a hydraulic actuator is operated at a low speed. Due to the fact parameters of the friction model are effected by the system condition, an adaptive friction compensation (AFC) controller is designed through the Backstepping method, and a dual-observer has been implemented to estimate the friction state. The global asymptotic convergence of a closed-loop system is proven by the Lyapunov theorem. The simulation results show that the positional accuracy of the adaptive friction compensation yiedls a significant improvement in the vehicle height adjustment as compared to the PID control, demonstrating the effectiveness of the adaptive fiction compensation method in the vehicle height adjustable system of the hydro-pneumatic suspension.     

车辆双筒式减振器热物性影响规律分析

为了探讨车辆减振器热物性对其温升的影响规律,建立了某车辆双筒液压充气减振器的热流量传递模型和物理传热模型,推导其导热、对流换热及辐射换热方程,通过热力学第一定律建立减振器热力学模型.利用迭代算法计算出此减振器达到热平衡时的温度和工作时间,并通过台架试验验证了建模的正确性,分析了减振器热物性对其温升的影响规律,最后进行了相关的灵敏度分析.研究结果表明减振器的4种热物性参数:油液密度、油液导热系数、油液比热容、缸体辐射发射率影响其温升特性,而缸体导热系数这一热物性参数对其温升特性无影响.     

基于李雅普诺夫和相平面图的车辆失稳机理研究

为了提高分布式驱动无人驾驶平台的操纵稳定性,基于李雅普诺夫第一法和相平面图对车辆的失稳机理进行了系统的分析.首先建立基于Fiala轮胎模型的非线性二自由度车辆动力学模型;然后对车辆非线性系统平衡点进行求解并分析;最后在不同工况下分析车辆的质心侧偏角和横摆角速度相平面图,并对稳定性条件和失稳机理进行了分析.研究结果表明:当车轮转向角小于分叉点对应的转向角度时,车辆能够很好地执行驾驶意图;当车轮转向角大于分叉点对应的角度,则稳定平衡点消失,从而导致车辆失稳.该方法为车辆稳定性分析提供了理论依据.     

基于ADAMS模型的履带车辆半主动悬挂自适应控制

建立了某履带车辆ADAMS整车模型。搭建了控制算法MATLAB与实体模型ADAMS之间的联合仿真接口。提出了采用模糊控制器调整PID调节器参数实现基于ADAMS建模的整车半主动悬挂控制策略。用动行程及其变化率作为模糊控制器的输入,通过模糊控制器的输出动态调整PID调节器的参数,形成了车辆半主动悬挂自适应控制系统。仿真研究表明,该自适应控制系统能够有效协调加速度和动行程在不同频段的矛盾,明显改善履带车辆行驶的平顺性。     

履带式车辆半主动悬挂的自适应控制

根据军用履带式车辆对悬挂系统的要求,对半主动悬挂1/4车模型进行了理论分析,在此基行础上对控制模型在有限带宽内进行了降阶简化.以振动加速度和悬架变形的加权二次型最小为控制性能指标,进行了线性高斯二次控制器(LQG)的设计,并以此作为模型参考自适应控制系统的参考模型.运用李雅谱诺夫稳定性理论设计了直接模型参考自适应控制系统(MRAC).仿真研究表明,MRAC能够适应悬架系统参数的变化,跟踪LQG控制的最优性能,该系统对路面变化和悬架系统参数变化均具有良好的自适应性和鲁棒性.     

履带式车辆半主动悬挂系统的建模与仿真

在履带式车辆1/2车8自由度平顺性控制建模过程中,利用增广变换的方法消去状态方程中路面高度输入的微分项,建立了半主动悬挂系统的标准状态方程数学模型;通过仿真分析车体质心加速度指标的幅频特性、功率谱密度特性、脉冲响应特性,并与理论计算或实测数据比较,验证了所建模型的正确性;在时域上模拟典型路面激励系统,通过比较被动悬挂与半主动悬挂驾驶员座椅处的加速度响应,验证了模型的可控性。     

Thermal Analysis of Vehicular Twin-Tube Hydraulic Gas-Precharged Shock Absorbers

In this study of temperature rising in vehicular twin-tube hydraulic gas-precharged shock absorbers,thermodynamic analyses were conducted via simulations.Equations on heat conduction,heat convection as well as radiation were derived by applying certain laws governing heat transfer;an equivalent thermal resistance network model of a shock absorber undergoing heat transfer was established innovatively;moreover,the shock absorber’s thermodynamic model of control volume system was built by using the first law o...     

车辆筒式减振器CAD系统的研发

为改善车辆筒式减振器传统设计方法上的不足,依照CAD技术在减振器设计中的应用,提出了完整的筒式减振器CAD系统的结构图和设计方案,开发出减振器CAD系统中的一个重要模块--减振器信息数据库系统,采用VC++、Visual FoxPro、MATLAB、AutoCAD等软件进行联合编程的方式创建减振器CAD系统。研发结果可为车辆筒式减振器计算机辅助设计提供参考。     

履带车辆肘内式半主动油气悬挂性能研究

肘内式油气悬挂与传统油气弹簧相比,能够以较小的体积和质量,提供更高的负载能力。将履带车辆肘内式油气悬挂单轮模型与半主动控制相结合,进行了半主动肘内式油气悬挂动态特性分析,提出了基于天棚算法的半主动双环控制策略,外环控制器计算目标阻尼力对应的阀芯位置,内环控制器控制阀芯跟踪目标位置,从而达到改善履带车辆平顺性的目的。探索了Virtual.Lab,AMESim和Matlab之间的集成接口,搭建了机电液耦合系统的联合仿真虚拟试验平台,并在该平台对控制算法进行了验证,结果表明肘内式油气悬挂半主动性能显著优于被动悬挂。     

Linear Quadratic Integral Control for the Active Suspension of Vehicle

The quarter model of an active suspension is established in the form of controllable autoregressive moving average （CARMA） model. An accelerometer can be mounted on the wheel hub for measuring road disturbance; this signal is used to identify the CARMA model parameters by recursive forgetting factors least square method. The linear quadratic integral （LQI） control method for the active suspension is presented. The LQI control algorithm is fit for vehicle suspension control, for the control performance index can comprise multi controlled variables. The simulation results show that the vertical acceleration and suspension travel both are decreased with the LQI control in the low frequency band, and the suspension travel is increased with the LQI control in the middle or high frequency band. The suspension travel is very small in the middle or high frequency band, the suspension bottoming stop will not happen, so the vehicle ride quality can be improved apparently by the LQI control.