针对采用钢丝绳的力控制系统的设计问题,探讨了悬吊减重系统的对象模型和控制律。所研究的系统是一种用来减轻部分体重的系统,应用于进行行走训练的病人。分析指出钢丝绳系统对象的传递函数在所用的频段内就是一个比例项。所以该系统宜采用积分控制,或者对钢丝绳采用速率控制。讨论了这种积分控制系统的调试方法,由于系统的带宽相对较窄,所以一般还需要用扰动观测器来对扰动进行补偿。给出了包含有三次谐波扰动的观测器设计,观测器设计中钢丝绳对象仍是基于一阶的假设。仿真实验中采用了实际的系统模型,仿真还给出了扰动中高次谐波对系统性能的影响。
The design problem of the force control with a steel cable is studied.The dynamic model of the plant and the control law are discussed.The system is a partial body weight support system applied to patients stepping on a treadmill.Analysis showed that the transfer function of the plant of such systems was a proportional term in the frequency range available.So an integral control was suitable for such systems with a steel cable.And it was suitable to use a proportional speed control for lifting or lowering of the steel cable.The tuning of the system was discussed.Because the bandwidth of such systems was relatively low,a disturbance observer was necessary for disturbance compensation.A disturbance model of up to third harmonic was proposed for the observer design.The observer was based on the first-order assumption of the steel cable system and was verified by simulation with the real system model.The influence of the higher harmonics of the disturbance on the system performance was also illustrated by simulation.