Force Tracking Impedance Control Based on Contour Following Algorithm

The original impedance control is a main force control scheme widely used in robotic force tracking. However, it is difficult to achieve a good force tracking performance in uncertain environment. This paper introduces a modification of the impedance control scheme which has the adaptability to track the desired force in uncertain environment (in terms of the varying location of the environment relative to the manipulators). The relation function of contact force in adjacent control period is derived to estimate the trajectory inclination angle deviation (IAD) of the manipulator. After that, the contour following algorithm which is implemented under a PID controller is proposed. To achieve force tracking impedance control under uncertain environment location, the movement of the manipulator in one control period is determined by estimating the new velocity vector and calculating the impedance correction online, which is based on the position-based impedance control (PBIC). Experiments was presented for testing the performance of IAD estimation and force tracking.