关键词: 力控制, 力矩控制, 力外环控制, 空间机器人

Abstract: The ability of force control for space robots is crucial for tasks which require robots to interact with the environment, such as space assembling. Utilizing joint torque sensors of the manipulator, in this article, a novel explicit force control strategy based on impedance inner loop control is proposed in which an impedance controller is selected as the inner loop instead of the traditional position controller. The impedance inner loop controller guarantees the compliance of the robot and the outer loop modifies the reference trajectory of the inner loop based on force errors between the desired and actual forces, thus realizing force tracking control. Furthermore, in order to validate the contact force of the endeffector measured indirectly by joint torque sensors, a high precision wrist force/torque sensor mounted on the manipulator is used to measure the real contact force directly. Force tracking experiments of contacting various stiffness environments of sponge, foam, and iron surfaces have been performed under both position inner loop control and impedance inner loop control. Experimental results show that the proposed method exhibits more stable force tracking performance while contacting different environments. The effectiveness of the proposed method is especially obvious for high stiffness environment, such as iron material.

Key words: force control, torque control, explicit force control, space robot