考虑参数不确定性的移动机器人轨迹跟踪控制

针对移动机器人系统中轮胎半径和轮胎间距存在的参数不确定性问题,提出自适应轨迹跟踪控制方法.首先,推导适合进行自适应控制器设计的系统误差模型,将原有控制问题转化为不确定参数的自适应更新率和虚拟控制输入的设计问题;然后,针对系统中的不确定性参数,设计自适应更新率对其进行在线估计,并设计虚拟的控制输入,得到移动机器人驱动电机的左右轮转速;其次在Lyapunov稳定性框架下证明闭环跟踪误差系统的渐近稳定性和估计误差系统的稳定性;最后通过仿真和实验表明,所提出方法能够通过在线学习估计出参数真实值,使得实际运行轨迹收敛到参考轨迹,同时表明所提出方法能够抑制系统参数不确定性对控制系统的影响.

Trajectory tracking control of mobile robot with parameter uncertainties

In order to improve the motion control accuracy of mobile robots, this paper proposes an adaptive tracking control method for mobile robots, considering the uncertainty of tire radius and tire pitch. Firstly, a kinematic based system error model for adaptive controller design is derived, and the original control problem is transformed into the design of adaptive updating rate and virtual control input. Then, in order to do with the uncertainty of tire radius and tire pitch in the system, an adaptive method is used to estimate it online, and a virtual control input is designed. By combining the virtual control input with the adaptive estimation algorithm, the left and right wheel speed of the driving motor is obtained. At the same time, it is proved that the closed-loop system is asymptotic stable and the estimation error is bounded in the Lyapunov framework. Finally, the simulation and experimental results show that, the proposed method can estimate the true values of these parameters by online learning, which makes the actual trajectory converge to the reference trajectory, and shows that the proposed method can suppress the influence of the system parameters variation on the control performance.