Variable admittance contact interaction and safety response control of redundant robot based on force and velocity

Human–robot interaction is an important research content in the robot field. In order to achieve the compliance and cooperation of human–robot interaction process, variable parameter interaction control and contact collision response of human-redundant robot are studied. Firstly, the kinematics model of redundant robot is established, and an inverse kinematics algorithm based on the augmented Jacobian matrix is proposed with the optimization objective of avoiding joint limit. Then, the admittance control model of human–robot interaction is established, and variable admittance control based on force and velocity is proposed. The contact intention of human is judged by the vector product relationship between external force and velocity. The control parameters are adjusted to better ensure the friendliness of human–robot cooperation. When the external force is applied to robot, based on human–robot interaction control law, robot motion is controlled, and the robot can move in the direction of the force, so the goal of human–robot compliance interaction is realized. When the external force is suddenly withdrawn, by adding the stiffness coefficient, the robot moves along the direction of the force and then can return to the position where the previous force is applied, achieving the safety response to robot's contact collision.