Development of Human-Robot Cooperative System Equipped with Mechanism to Detect the Contact Conditions between Robot and External Environment

Abstract

The purpose of this study is to develop a human-robot cooperative system that comes in contact with external environment without the contact stability problem. The system is composed of a force-and-displacement detection interface, a shock absorber mechanism to detect contact conditions, a force sensor and a robot. The motions of the system are controlled according to impedance control strategy. In this study, the mechanical device to detect the contact conditions between the robot and the external environment is developed, and a robot motion control method with the proposed device is proposed. The proposed device is composed of following two components: (i) three shock absorbers to absorb contact force arisen from an interaction between a device tip and an external environment; (ii) three laser sensors to detect the displacement of the shock absorbers. The magnitude of the detected displacement is used as control input of the motion of the robot. Stability analyses of the proposed system were carried out to identify impedance parameters applied to the motion of the interface and the robot. Human-robot cooperative contact tracing experiments were carried out to confirm the effectiveness of the system. The experimental results show that (i) the proposed mechanical device and the proposed control method make the control system stable and that (ii) the robot comes in contact with the external environment without the contact stability problem.