基于非线性级联系统的弹性关节空间机器人新型滑模控制

A NOVEL SLIDING MODE CONTROL OF ELASTIC-JOINT SPACE ROBOT BASED ON NONLINEAR CASCADE SYSTEMS

研究了双臂弹性关节空间机器人的改进型非线性干扰观测器(nonlinear disturbance observer,NDO)设计、新型自适应动态终端滑模控制和弹性振动抑制问题。首先,考虑空间机器人的关节弹性,基于非线性级联系统的结构建立弹性关节空间机器人模型,分为外环机械臂动力学和内环关节动力学,具有渐近稳定性。针对外环机械臂动力学模型,设计基于改进型NDO的新型自适应动态终端滑模控制算法。针对内环关节动力学模型,设计力矩反馈控制算法来抑制弹性关节振动。本文提出的基于非线性级联系统的自适应动态终端滑模控制算法具有良好的动态特性及较强的鲁棒性,可在关节柔性刚度较小情况下,快速完成弹性关节振动抑制,实现空间机器人轨迹的精确跟踪。系统仿真试验证明了本文控制算法的正确性。

This paper discusses the design of an improved nonlinear disturbance observer(NDO), a novel adaptive dynamic terminal sliding mode control, and the elastic vibration suppression problem of the dual-arm elastic-joint space robot. Firstly, assuming that the joint of the space robot is elastic,an elastic joint space robot model is established based on the structure of the nonlinear cascade system. The model can be divided into an outer loop manipulator dynamic model and an inner loop joint dynamic model with asymptotic stability.Then, for the dynamic model of the outer loop manipulator, a novel adaptive dynamic terminal sliding mode control algorithm is designed based on the improved NDO. For the inner loop joint dynamic model, the torque feedback control algorithm is designed to suppress the elastic vibration of the flexible joints. The adaptive dynamic terminal sliding mode control algorithm is designed based on the nonlinear cascading system proposed in this paper with good dynamic characteristics and robustness. It can quickly suppress the vibration of the elastic joints under the condition of small flexible stiffness of joints, and achieve the accurate trajectory tracking of the space robots. The system simulation comparison test shows the effectiveness of the control algorithm.