Adaptive Impedance Control in Dynamic Environment Based on Nonlinear Tracking Differentiator

In the field of force and position control for robots, impedance control is prevalently employed. However, in complex dynamic environments such as cleaning and grinding, constant impedance control has a large tracking error and may even damage the robot’s end tool. In order to solve these problems, an adaptive variable impedance control method is presented based on a nonlinear tracking differentiator in this paper. Specifically, we design the adaptive rate based on Proportional Integral (PI) control to perform the tracking of force and position in complex dynamic environments. Meanwhile, a nonlinear tracking differentiator is developed to lessen the impulse of contact force generated when the end-effector just contacts with environmental surface. The experiments show that the presented approaches effectively improve the safety and reliability of the contact operations.