Abstract: Aiming at how to quickly and smoothly eliminate the distance error and angle error caused by the approaching during the Automated Guided Vehicles(AGV)trajectory tracking process,a sliding mode trajectory tracking control method of improved constant velocity reaching law was proposed.The AGV kinematics model was established in the global coordinate system,and the sliding mode shear function of AGV was obtained based on the control strategy of Backstepping to deal with nonlinear system,thus solving the difficulty of switching function of sliding mode control in nonlinear system.In order to better achieve the AGV from any initial deviation state to the sliding mode switching surface,the switching function and the trajectory tracking control law based on the improved constant velocity reaching law of AGV sliding mode control was established by replacing the symbol function in the original reaching law with a continuous function,which was in response to the influence of the constant ε in the constant velocity reaching law on the approaching process.The simulation data and experimental results showed that the proposed trajectory tracking control method could make AGV achieve faster error correction at different turning radius and different speeds,and ultimately make the system stable.

Key words: automated guided vehicles, trajectory tracking, Backstepping, sliding mode shear function, improved constant velocity reaching law, nonlinear system

摘要： 针对自动导引小车(AGV)轨迹跟踪过程中如何快速平稳消除行进所产生的距离和角度误差问题,提出了一种改进等速趋近律的滑模轨迹跟踪控制方法。在全局坐标系下建立了AGV运动学模型,基于反演算法(Backstepping)处理非线性系统的控制策略得到AGV的滑模切换函数,从而解决了非线性系统滑模控制切换函数难的问题;为了更好地实现AGV从任意初始的偏差状态达到滑模切换面,针对等速趋近律中ε常数对趋近过程的影响,通过连续的函数取代原趋近律中的符号函数,得到基于改进等速趋近律AGV滑模控制的切换函数式和轨迹跟踪的控制律式。通过仿真数据与实验结果表明,所提出的轨迹跟踪控制方法能够使AGV在不同转弯半径和不同速度下均能实现较快的误差纠偏,并最终使系统趋于稳定。

关键词: 自动导引小车, 轨迹跟踪, 反演算法, 滑模切换函数, 改进等速趋近律, 非线性系统