路面附着系数与车辆稳定性控制的效果紧密联系,因此有必要在考虑路面影响的情况下设计一种能够适用于多种路面的质心侧偏角控制策略。在7自由度非线性动力学模型的基础上,由车轮侧向力与路面附着的关系,分析不同路面对质心侧偏角控制的影响。根据路面附着系数的不同,通过定义极限边界和线性区域边界,设计变化的动态质心侧偏角安全边界。根据横摆角速度增益判断车辆是否处于非线性状态,并在有逼近安全边界的趋势时提前施加控制,以避免产生由车轮纵向力增加引起的侧向力减小所造成的加剧车辆侧滑的趋势。基于非线性输入的滑模控制算法设计质心侧偏角控制器。通过Matlab/Simulink仿真和实车试验验证了该控制方法能够在不同附着路面条件下的有效地保证汽车的行驶稳定性。
Road friction is closely related to the performance of vehicle stability control system. Thus it is necessary to design a vehicle side-slip angle based control threshold for different kinds of road conditions. First the vehicle 7 DOFs nonlinear dynamic model is created. According to the features between wheel lateral force and road friction, the side slip angle control strategy is studied. The upper limit border and the linear region border are defined to design the side slip angle dynamic border which is varying with the road friction. According to the wheel force model, the lateral force will decrease while braking and the side slip trend will strengthened. To avoid such trend, the control offset is adjusted basing on yaw rate gain to maintain vehicle stability in advance. The side slip angle controller is designed based on the nonlinear input sliding mode control strategy. The simulation and experiment results verified the effectiveness of the vehicle stability control strategy.