An impedance control method in null-space for 7-degree-of-freedom redundant manipulators is presented in this article. The null-space impedance motion of the redundant manipulator was described in the angle domain and a null-space impedance equation was established. To successfully obtain joint angular velocity, a high-gain observer is designed. The stability of the proposed control method was proved based on passive theory. The proposed null-space impedance control method not only preserved the Cartesian space impedance characteristics of the redundant manipulator but also achieved null-space impedance control. When the manipulator interacted with the outside world, the position error of the end effector asymptotically converged due to the self-motion of the manipulator. Simulations and experiments of the general impedance control method and the proposed impedance control method verified the effectiveness of the proposed method.

中文翻译：

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基于臂角的7自由度冗余机械臂零空间阻抗控制

本文介绍了一种用于 7 自由度冗余机械臂的零空间阻抗控制方法。在角度域中描述了冗余机械臂的零空间阻抗运动，并建立了零空间阻抗方程。为了成功获得关节角速度，设计了一个高增益观测器。基于被动理论证明了所提出的控制方法的稳定性。所提出的零空间阻抗控制方法既保留了冗余机械臂的笛卡尔空间阻抗特性，又实现了零空间阻抗控制。当机械手与外界交互时，由于机械手的自身运动，末端执行器的位置误差逐渐收敛。