Abstract: To improve the trajectory tracking control performance of SCARA robot, a sliding mode control strategy based on nonsingular terminal sliding mode surface and the improved fast reaching law is proposed. A fast nonsingular terminal sliding mode surface is designed, which can converge to equilibrium point under arbitrary initial state and the convergence speed is faster than the traditional terminal sliding surface. The reaching law of improved sliding mode control can restrain the chattering effectively whilst also guaranteeing fast approaching, and with the use of hyperbolic tangent function instead of the traditional symbol function, the high frequency chattering is eliminated effectively. Furthermore, a fuzzy control method is utilized to adjust the parameters of the reaching law, improving the torque impact problems caused by too big initial state error. Simulation results which is based on SCARA robot model show that the tracking performance is good, the output torque is smooth.

Key words: trajectory tracking control, fuzzy control, sliding surface, reaching law, chattering

摘要： 为了提高SCARA机器人的轨迹跟踪控制性能，提出了一种基于非奇异终端滑模面和改进的快速趋近律的滑模控制策略。设计了一种非奇异的快速终端滑模面，可在任意初始状态下收敛到平衡点；改进滑模控制的趋近律，在保证快速趋近的同时可有效抑制抖振，并采用双曲正切函数代替传统的符号函数，有效地消除了高频抖振。采用模糊控制调节趋近律参数，改善初始状态误差过大时引起的力矩冲击问题；基于SCARA机器人模型仿真实验表明，实验结果跟踪性能良好，输出力矩平滑。

关键词: 轨迹跟踪控制, 模糊控制, 滑模面, 趋近律, 抖振