Integration of impedance control and manipulability regulation for a finger-arm robot

Motion control algorithms were proposed for a 9-DOF finger-arm robot by using the finger manipulability obtained in a previous study. However, in the previous study, only methods for achieving unconstrained movement of the finger-arm robot were discussed. In this paper, the authors propose a novel method for having a finger-arm robot complete a constrained task by integrating impedance control with manipulability control of the finger. First, methods of applying the previous heuristic method to the passive impedance control and the active impedance control were developed; and experiments were performed to demonstrate the features. Then, an impedance control combined with the steepest ascent method to modulate the manipulability of the finger was proposed. The proposed method demonstrates a strong performance even when a dynamic external force is 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 during both the unconstrained and the constrained tasks.