下肢负荷外骨骼的变负载控制研究

Research about Variable Load Control Algorithm Applied to the Lower Extremity Assist Exoskeleton

下肢负荷外骨骼需要在变负载情况下实现助力的功能,外骨骼应能准确地跟踪人体的期望运动轨迹。为此,基于系统的动力学模型,提出了鲁棒自适应PD控制方法。该方法将系统外界的干扰、关节摩擦和噪声统一为上确界已知的干扰项,在控制器设计时引入中间变量,计算出以关节变量为参数的回归矩阵和一个描述外骨骼质量特性的未知定常参数向量,利用回归矩阵和引入的中间变量设计自适应律。仿真结果表明,外骨骼能够准确跟踪上期望的运动轨迹,系统的鲁棒性得到改善,实现了系统变负载控制的目的。

Lower extremity exoskeleton need to achieve the function of power under condition of the changing load and accurately track the trajectory of the body＇s expectations. Based on the system＇s dynamic equation, the Robust Adaptive PD control method was proposed in this paper. The disturbance outside system, joint friction and noise were taken as the upper bound known disturbance item. In the designing controller, middle variable was introduced to calculate the regression matrix, which the joint variables are the parameters of, and the constant unknown vector, which describes the mass characters of the exoskeleton. The adaptive law was designed with the re- gression matrix and middle variable. Simulation results show that, the exoskeleton can exactly track the desired trajectory to improve the robustness of the system and to achieve variable load control.