Hybrid Visual Servoing for Rivet-in-hole Insertion Based on Super-twisting Sliding Mode Control

Aiming at solving the rivet-in-hole insertion problem of the complement riveting process, a novel hybrid visual servoing controller is proposed for an automatic drilling and riveting system, in which, combination of visual and laser sensor feedback is adopted to determine the relative pose errors of the rivet with respect to the hole. To compensate the system uncertainties, a super-twisting sliding mode controller (STSMC) is designed to provide continuous control inputs, and the end-effector can move to the desired pose by exponentially decreasing the feature errors. The proposed control scheme not only guarantees the stability of the control system but also provides a robust and quick rivet spot-positioning in the presence of manipulator errors and external disturbances of the riveting system. Finally, rivet-in-hole insertion experiments were conducted, the results show that accurate positioning can be achieved within a finite time (1~5s) which meets the demand of high-efficiency and flexibility in the riveting process since it can achieve global convergence from any initial camera pose as long as the hole is in the field-of-view (FOV) and the laser displacement sensors are in the working range at the beginning.