机器人辅助作业轨迹跟踪控制方法研究

Research on trajectory tracking control method of robot⁃assisted operation

机器人辅助作业过程中具有不确定外部力干扰情况下的交互控制问题,为此,文中提出一种基于误差的PD协同滑模阻抗控制模型的上肢康复机器人交互控制策略,以实现人机系统较好的轨迹跟踪精度与柔顺性。首先,对欠自由度上肢康复训练机器人完成运动学与动力学建模,以保证机器人可以跟踪预设轨迹;其次,针对滑模阻抗控制模型人机系统阻尼特性较好,但轨迹跟踪精度较差的问题,设计基于误差的PD协同阻抗控制模型。将交互过程中人施加的外部力视为干扰,在外力迫使机器人运动误差较小的情况下,采用PD控制模型减小康复训练过程中误差;而在外力迫使机器人产生较大误差时,采用滑模阻抗控制模型,保持系统良好的柔顺性。最后,通过仿真分析较大的外部干扰对系统的影响,并验证所提策略的有效性。结果表明,所提策略可以实现人机系统较高的轨迹跟踪精度与良好的柔顺性,与滑模阻抗控制策略相比,在外界力突变情况下,轨迹跟踪精度提升15.5%,关节力误差降低4.1%。

In the process of robot⁃assisted operation,there is an interactive control problem under the condition of uncertain external force interference.An interactive control strategy for upper limb rehabilitation robots of error⁃based PD collaborative sliding mode impedance control model is proposed to achieve better trajectory tracking accuracy and flexibility for the human⁃machine system.The kinematics and dynamics modeling of the lower⁃degree⁃of⁃freedom upper limb rehabilitation training robot is completed to ensure that the robot can track the preset trajectory.In allusion to the problem that the man⁃machine system of sliding mode impedance control model has good damping characteristics but poor tracking accuracy,an error⁃based PD cooperative impedance control model is designed,and the PD control model is adopted to reduce the error in the rehabilitation training process.The external force exerted by the human during the interaction process is regarded as interference under the condition that the robot is forced by the the external force to move with small motion error.The sliding mode impedance control model is adopted to maintain the good compliance of the system when the robot is forced by the external force to make bigger errors.The impact of large external interference on the system are conducted by means of the simulation analysis,and the effectiveness of the proposed strategy is verified.The results show that the proposed strategy can achieve better trajectory tracking accuracy and good flexibility for the human⁃machine system.In comparison with the sliding mode impedance control strategy,the trajectory tracking accuray is improved 15.5%and the joint force error is reduced by 4.1%under the sudden change of external force.