基于逼近误差调节的髋关节康复机器人自适应模糊容错控制算法的研究
Adaptive Fuzzy Fault-tolerant Control Algorithm of a Therapeutic Robot for Hip-joint Rehabilitation Based on Adjustments of Approximation Errors
针对基于人体生物动力学设计的一种髋关节康复机器人, 在模型参数不确定的情况下, 研究执行器故障容错控制问题. 根据人体髋关节活动特点, 给出了康复训练中期望跟踪轨线的数学表达式; 对康复机器人的旋转驱动器提出了基于分层模糊系统的间接型自适应容错控制算法, 对4个线性驱动器给出了直接型自适应模糊容错控制算法. 该方法对逼近误差估计值在线调节, 用此估计值设计补偿控制项以减小逼近误差对跟踪精度的影响. 基于Lyapunov理论, 对所设计的控制方案作了稳定性分析. 此外, 还给出了矩阵Lyapunov方程解的特征值的性质, 为减小跟踪误差提供了理论依据. 仿真结果表明所提出的控制方案可使髋关节康复机器人圆满完成训练任务.
Aiming at the hip-joint rehabilitation robot designed based on human biodynamics, the effective fault-tolerant control algorithm for actuator faults are developed in rehabilitation exercise under parameter uncertainty. The mathematical expressions of the desired tracking trajectories are provided according to the movement characteristic of hip-joint. For the power rotary actuator, an indirect adaptive control algorithm is proposed based on hierarchical fuzzy system, and a direct adaptive fuzzy control algorithm is proposed for four linear actuators. The approximation errors are estimated by online adjustment, which is utilized to design compensator to reduce the effect on tracking precision caused by approximation errors. The stability analysis of the proposed control scheme is carried out by using Lyapunov stability theory. In addition, the author gives the properties of the eigenvalues of the solution of the matrix Lyapunov equation in two-dimensional space, which provides a theoretical basis for reducing tracking errors. The results of simulation indicate that the proposed control scheme can ensure the successful completion of the tasks of the robot performing hip-joint rehabilitation exercises.
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