基于PID理论的自触发MPC移动机器人控制方法

Mobile robot control using self-triggered model predictive control and PID theory

为解决常规自触发模型预测控制(STMPC)应用于移动机器人系统会因为附加扰动而产生系统状态突变问题,针对具有输入、输出约束及附加扰动的移动机器人系统,提出一种基于比例、微分和积分(PID)的自触发模型预测控制(PID-STMPC)算法,以降低最优控制问题(OCP)的求解频次,并削弱残余误差和状态突变对机器人的系统影响。在实际移动机器人系统中对所开发的PID-STMPC算法有效性进行了实验验证。实验结果表明:与常规STMPC相比,所提出的PID-STMPC策略,能够有效提高机器人系统的控制性能,在减少系统54.63%响应时间的同时降低控制器84.62%的计算资源消耗。

Nonlinear mobile robot has become an indispensable intelligent device,thus it is very important to research for its control algorithm.Since self-triggered model predictive control(STMPC)can not only be indicated to deal with robot constraints but also reduce resource consumption,the application of STMPC in robotics has been widely concerned.However,the existing STMPC strategy constructs the self-triggering condition only by the error of a single sampling moment,ignoring the state mutation of the system due to the accumulation of state error.Therefore,in order to solve the problem of system state mutation due to additional perturbation in the traditional self-triggered model predictive control for a mobile robot system,a proportional,differential and integral(PID)based STMPC(PID-STMPC)algorithm is proposed.Firstly,based on the two-wheel differential mobile robot system model and its additional constraints,a“Dual-mode model predictive control(MPC)”controller is designed;secondly,a self-triggering mechanism based on PID of error information between the actual state and its optimal prediction is constructed by ensuring that the cost function is strictly decreasing,which not only reduces the solving frequency of the optimal control problem(OCP)but also weakens the effects of residual error and state mutation on the robot system;then,the PID-STMPC algorithm is designed by combining the“Dual-mode MPC”and the self-triggering mechanism based on PID information;finally,the effectiveness of the developed PID-STMPC algorithm is verified by experiments in a real mobile robot system.As shown in the experiment results,compared with the standard STMPC strategy,the proposed PID-STMPC method can not only effectively improve the control performance,but also reduce by 84.62%computational resources while shortening the response time by 54.63%.