气动人工肌肉关节的建模与仿真

Modelling and simulation of joint actuated by pneumatic muscles

为降低传统气动系统的成本,设计了气动人工肌肉(PMA)驱动的单自由度(DOF)运动关节系统.在研究PMA和脉宽调制(PWM)高速开关阀特性的基础上,建立了系统的多输入4阶仿射非线性数学模型.仿真分析了系统在不同输入控制量下的静、动态输出特性,并分别研究了摩擦力、负载、气源压力和工作容积4个主要因素对系统特性的影响.仿真结果表明,该系统开环稳定,且不论摩擦力存在与否,系统输入输出都存在着良好的静态线性关系,但静摩擦力影响稳态输出值,增加负载或减小气源压力都将引起系统超调和震荡加剧,而减小PMA内部的工作容积可以提高系统响应.

For reducing the cost of traditional pneumatic systems,a one degree of freedom（DOF） joint system driven by pneumatic muscle actuators （PMAs） was designed. Based on characteristics of PMAs and pulse-width modulation （PWM） high-speed on-off valves, the multi-input 4th-order affine nonlinear math- ematical model of the system was achieved. The system static and dynamic output characteristics under different control inputs were simulated and analyzed. The influences of four major factors including friction, load, supply pressure and working volume on system characteristics were studied. The results show that the system is open-loop stable, approximative static input-output linearity exists regardless of the friction force presence, but the static friction impacts the stable output. Both the increasing load and the reducing supply pressure can exacerbate output fluctuations and overshooting. System response can be improved after reducing the internal working volume of PMAs.