柔性空间机器人基于关节柔性补偿控制器与虚拟力概念的模糊全局滑模控制及振动主动抑制

Adaptive fuzzy global sliding mode control and active hierarchical vibration suppression of space robot with flexible-link and flexible-joint

空间机器人系统的柔性主要体现在空间机器人的臂杆和连接各臂杆之间的铰关节;由于空间机器人系统结构的复杂性,以往研究人员对同时具有柔性关节和柔性臂的系统关注不够;为此讨论了参数不确定情况下柔性关节、柔性臂空间机器人系统的动力学模拟、运动控制方案设计和以及臂、关节双重柔性振动的分阶主动抑制问题。依据线动量、角动量守恒关系并基于拉格朗日方程、线性扭转弹簧及假设模态法推导了系统动力学模型;以此为基础;针对空间机器人实际应用中各关节铰具有较强柔性的情况,引入了关节柔性补偿控制器并结合奇异摄动技术将整个系统分解成独立时间尺度的电机力矩动力子系统和柔性臂子系统;针对电机力矩动力子系统,设计了力矩微分反馈控制器来抑制关节柔性引起的系统弹性振动;针对柔性臂子系统,提出了一种基于虚拟力概念的自适应模糊全局滑模控制方案,由于运用了虚拟力的概念,从而通过仅设计一个控制输入就可达到既跟踪期望轨迹又抑制柔性臂柔性振动的控制目标。计算机数值仿真对比实验证实了该方法的可靠性和有效性。

The flexibility of space robot system mainly embodies in its arm bars and hinge joints connecting the arm bars. The dynamics simulation of an space robot system with flexible joints and flexible arms were carried out,the motion control algorithm was designed and the active hierarchical vibration inhibition of flexible arms and joints was investigated under the situation of all the parameters uncertain. According to the principle of conservation of momentum and moment of momentum,and based on Lagrange equations,the dynamic model of the system was deduced under the supposition of linear torsion spring and by using the hypothesis modal method. On this basis,considering the actual situation that each hinge joint has strong flexibility in space robot,a flexible joint compensation controller was introduced and making use of the singular perturbation technology,the whole system was decomposed into a motor moment power subsystem and a flexible arm subsystem with independent time scale. For the motor moment power subsystem,a moment differential feedback controller was designed to inhibit the elastic vibration caused by joint flexibility. For the flexible arm subsystem,an adaptive fuzzy global sliding mode control scheme was proposed based on the concept of virtual force. By using the concept of virtual force,the control target of not only tracking the expected trajectory,but also inhibiting the vibration of flexible arm was achieved by only designing a control input. The results of numerical simulations testify the reliability and availability of the scheme proposed.