传统纯跟踪控制器在面向实际应用时往往难以较好地处理传感器信号延时、执行器响应滞后等因素带来的控制滞后问题以及欠缺内外部扰动干预下的自主抗干扰能力;同时在跟踪临近终点的目标点时,因前视距离作为控制律的分母且逐渐减小,导致输入转角值发生突变且伴随方向盘出现不稳定地晃动现象,影响行驶稳定性及人员乘坐体验感.针对此,提出了 一种基于改进纯跟踪的路径跟踪控制器.首先,构建了纯跟踪控制器的基础模型并为改善纯跟踪控制的滞后影响,建立了一种结合规划路径和规划速度信息的道路预瞄模型.然后考虑系统因内部及外部环境影响产生的未知干扰并设计非线性扩张状态观测器(nonlinear expanded state observer,NESO)进行扰动估计及实时补偿,以提升纯跟踪控制器的抗干扰能力.并进一步通过转向稳定调节模型以改善纯跟踪控制器临近终点时的转角突变问题.最终,基于软件在环动力学仿真平台以不同初始航向及存在初始偏差工况下测试所提控制器的有效性,并进一步在实车平台进行闭环测试验证,实验结果表明改进的纯跟踪算法具有良好的跟踪精度和转向平顺性.
Path Tracking Control of Low-speed Intelligent Vehicles Based on Improved Pure Pursuit
The traditional pure pursuit controller is often difficult to deal with the control delay brought by the sensor signal delay,actuator response lag and other factors,as well as the lack of active anti-disturbance ability under the intervention of internal and exter-nal disturbances.At the same time,the preview distance is used as the denominator of the control law and it gradually will decrease when tracking the target point near the end,resulting in sudden changes in the input angle value and along with the unstable steering wheel,which affects the driving stability and the riding experience of the passengers.A path tracking controller based on improved pure pursuit was proposed.Firstly,the base model of the pure pursuit controller was constructed and a road preview model combining the planned path and the planned speed information was established to improve the lagging effect of the pure pursuit control.Then,the un-known disturbances generated by the internal and external environment of the system were considered,a nonlinear expanded state ob-server(NESO)was designed to estimate and compensate the disturbances in real time to enhance the anti-disturbance capability of the pure pursuit controller.Furthermore,a steering stability adjustment model was developed to improve the sudden change of steering an-gle when it's approaching the end point.Finally,the effectiveness of the proposed controller was tested on a software-in-the-loop dy-namics simulation platform with different initial heading and initial deviation conditions.Further,the proposed controller was verified in a closed-loop test on a real-world vehicle platform,and the experimental results show that improved pure pursuit algorithm has good tracking accuracy and steering smoothness.
intelligent vehiclespath trackingimproved pure pursuitroad previewnonlinear expanded state observeranti-disturbance
万方数据
维普
