基于期望阻抗行为的柔性关节控制器设计

Flexible joint controller design based on desired impedance behavior

针对柔性关节电机端力矩输入和负载端位置输出不匹配引起的定位精度低、力矩波动等问题,本文设计一种基于期望阻抗行为的柔性关节控制器,该控制器由内环力矩控制器和外环位置/阻抗控制器级联组成。对于力矩控制器,通过添加力矩反馈等效降低电机端惯量和摩擦力的影响,改善柔性关节动力学性能;对于位置/阻抗控制器,通过在负载端引入期望力矩,得到直接与环境交互的刚度和阻尼整定参数,并通过调节控制率参数实现柔性关节的位置/阻抗/力矩控制。应用李雅普诺夫稳定性理论证明了控制器的稳定性,通过Matlab/Simulink对该控制器进行了仿真分析,并基于自研的柔性关节样机进行了实验验证。仿真和实验结果表明:提出的柔性关节控制器在轨迹跟踪、振动抑制等方面具有良好的控制效果。

A novel flexible joint controller is designed on the basis of desired impedance behavior to solve the problems of low position accuracy and torque ripple caused by the mismatch between torque input at the motor side and position output at the load side.The controller comprises a torque controller in the inner loop,and a position/impedance controller cascades in the outer loop.The inertia and friction of the motor side for the torque controller can be weakened equivalently by adding torque feedback,improving the dynamic performance.For the position/impedance controller,the stiffness and damping tuning parameters that directly interact with the environment can be obtained by directly introducing the desired torque at the load side,and the position/impedance/torque control of flexible joints can be realized by adjusting control rate parameters.The stability of the controller was proven by Lyapunov stability theory,and the controller was simulated and analyzed by Matlab/Simulink.Finally,the performance of the controller was experimentally verified on a flexible joint prototype developed by the laboratory.Results show that the proposed flexible joint controller has good control effects in trajectory tracking and vibration suppression.