Human-redundant robot interaction and redundancy utilization based on three-dimensional force sensor

Abstract

To make full use of redundant characteristics, the inverse kinematics algorithm based on augmented Jacobian matrix with the goal of avoiding joint limit and obstacle is adopted. Then, admittance control system is established for human-robot interaction, and force control is converted into motion control of robot. Through the expansion of Jacobian matrix, the model of joint limit avoidance is established. Regarding obstacle avoidance in human-robot interaction process, the potential function gradient is calculated and augmented Jacobian matrix is formed. Thus, comprehensive control model of human-robot interaction and obstacle avoidance is established. When the external force is applied, the robot can move smoothly along the human hand. The robot's motion process is smooth and compliant. At the same time, when performing task of avoiding joint limit, the values of the joint angle are within the set range. The average angle margin of the four joints is over 60 %. So the goal of avoiding the joint limit is achieved. When adding obstacle avoidance in the interaction control, the difference value between the minimum distance and safe distance is always positive. The safety margin of the distance is over 20 %. So the robot does not contact with the obstacle. So human-robot interaction and redundancy utilization can be realized simultaneously.