轮式移动机器人的位置量测输出反馈轨迹跟踪控制

针对机器人的姿态角难以精确测量的困难,本文研究基于位置测量的轮式移动机器人的轨迹跟踪问题.首先提出一种利用机器人的位置信息估计其姿态角的降维状态观测器,当机器人的线速度严格大于零时,可保证姿态角观测误差的指数收敛.然后给出一种新的状态反馈轨迹跟踪控制律,当参考轨迹满足一定的激励条件时,可以保证机器人的线速度严格大于零且跟踪误差全局渐近收敛.进一步结合姿态角观测器和状态反馈控制律,得到一种输出反馈轨迹跟踪控制算法.理论分析表明,当参考轨迹满足一定的激励条件时,所提出的输出反馈控制算法可以保证跟踪误差的全局渐近收敛.最后对所提出的姿态角观测器、状态反馈和输出反馈轨迹跟踪控制算法进行了仿真验证,证实了算法的有效性,并且当存在位置测量误差时,所提出的输出反馈轨迹跟踪控制算法仍可以保证机器人对参考轨迹的实际跟踪.

Output feedback trajectory tracking control of wheeled mobile robots with position measurements

To cope with the difficulty in posture angle measurement of wheeled mobile robots (WMRs), we investigatethe trajectory tracking control problem with only position measurements in this work. Firstly, a reduced-order state observerfor posture angle is designed using position information, ensuring exponential convergence of the observing error providedthat the linear velocity of the robot keeps strictly positive. Under certain excitation conditions of the reference trajectory,we then propose a trajectory tracking control law using state feedback approach, guaranteeing the linear velocity of therobot strictly positive and the tracking errors globally convergent to zero. The proposed observer and state feedback controllaw are further combined to obtain the output feedback trajectory tracking control law. Theoretical analysis shows that,under certain excitation conditions of the reference trajectory, the obtained output feedback control law ensures that thetracking errors globally asymptotically tend to zero. Finally, numerical simulations are carried out to validate the proposedschemes, showing that the posture observer, the state and output feedback trajectory tracking control laws are all effective,and furthermore, the output feedback tracking control law can still achieve practical tracking of the reference trajectory inthe presence of position measurement errors.