针对无人驾驶车辆在复杂工况下的横向稳定性问题,提出一种基于反步滑模法的横向稳定性分层控制策略.首先,建立准确描述车辆运动的七自由度模型,选用Dugoff轮胎模型来描述轮胎与路面之间的动力学特性;然后,在运动控制层提出一种反步滑模控制算法,分别对纵向速度、侧向速度以及横摆角速度进行单独控制,得到它们在李雅普诺夫稳定条件下的控制率;在力矩分配层基于轮胎负荷率对轮胎的纵向力和侧向力进行重新分配;在执行层基于Dugoff轮胎逆模型和车轮模型计算得到前轮转角和车轮转矩;最后,构建出Matlab/Simulink-Carsim联合仿真平台,并在正弦留驻工况和连续正弦工况下对所提出的横向稳定性分层控制策略进行验证.仿真结果表明提出的控制策略能够有效地对无人驾驶车辆的横摆角速度、质心侧偏角进行控制;并且,相较于纯滑模控制器,反步滑模控制策略下的横摆角速度和质心侧偏角的平均绝对误差(Mean absolute error,MAE)和方均根误差(Root mean squared error,RMSE)较小,无人驾驶车辆的横向稳定性得到进一步提升.
Lateral Stability Control of Autonomous Vehicle Based on Backstepping Sliding Mode Method
A layered control strategy based on backstepping sliding mode method is proposed for the lateral stability of autonomous vehicles under complex conditions.Firstly,a seven-degree-of-freedom model is established to accurately describe the vehicle motion,and the Dugoff tire model is used to describe the dynamic characteristics between the tire and the road surface.Then,a backstepping sliding mode control algorithm is proposed in the motion control layer.The longitudinal velocity,lateral velocity and yaw rate are controlled separately to obtain their control law under Lyapunov stability conditions.In the torque distribution layer,the longitudinal force and lateral force of the tire are redistributed based on the tire load rate.In the execution layer,the front wheel angle and wheel torque are calculated based on the Dugoff tire inverse model and the wheel model.Finally,the Matlab/Simulink-Carsim joint simulation platform is constructed,and the proposed hierarchical control strategy of lateral stability is verified under sine dwell condition and continuous sine condition.The simulation results show that the yaw rate and sideslip angle of the autonomous vehicle can be effectively controlled by the control strategy proposed.Moreover,compared with the pure sliding mode controller,the MAE and RMSE values of yaw rate and sideslip angle under the backstepping sliding mode control strategy are smaller,and the lateral stability of the autonomous vehicle is further improved.
autonomous vehicleslateral stabilitybackstepping sliding mode controltorque distribution
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