Cooperative Impedance Control of a Finger-Arm Robot by Regulating Finger's Manipulability

Abstract

Algorithms of motion control for a 9-DOF finger-arm robot were proposed by using the finger's manipulability in a previous study. However, only the methods for completing an unconstrained motion of the finger-arm robot were discussed in the previous study. In this paper, the authors propose a novel method for a finger-arm robot to complete an impedance control by regulating finger's manipulability in a constrained task. Methods of combining the previous heuristic method to the passive impedance control and the active impedance control are firstly developed. Then, an impedance control combined with the steepest ascent method is also proposed. The features of the proposed methods are demonstrated through several experiments. The proposed impedance control method combing with the steepest ascent method shows a strong performance even when a dynamic external force was applied to the finger. By using the proposed method, the arm actively moves along a direction to effectively maintain the moving potential of the finger. As a result, the finger shows a robust performance to its singularity in both unconstrained and constrained tasks.