Disturbance Observer-Based Finite-Time Control Algorithm for Robotic Bolt-Tightening via Visual Feedback

The increasingly mature visual feedback technology has greatly promoted the development of high-altitude unmanned operations, particularly in bolt-tightening operations for the power transmission tower. Nevertheless, traditional control algorithms relying on visual feedback encounter specific difficulties and challenges during bolt-tightening tasks execution. This paper presents a disturbance observer-based finite-time control algorithm to reject disturbances during bolt-tightening operations and mechanical errors inherent to the robotic system. Through theoretical analysis of this algorithm, based on visual feedback technology and the finite-time control method, the finite-time stability of the overall closed-loop system is ensured. Both the simulation and experimental results are given to validate the feasibility of the proposed control method. Compared with traditional PID, LQR, and MPC controllers, the convergence speed is increased by more than 16%, and the accuracy of steady-state error is also increased by more than 22%, moreover, the success rate is as high as 98%. It is highlighted that the proposed control method has superior disturbance rejection capability, faster convergence speed, and better reliability. Note to Practitioners—This study addresses challenges in visual feedback-dependent bolt-tightening operations for power transmission towers. A novel disturbance observer-based finite-time control algorithm is introduced, ensuring the stability of the closed-loop system. The method excels in rejecting disturbances and minimizing mechanical errors during bolt-tightening tasks. The simulation and experimental results confirm its superiority over conventional controllers in terms of disturbance rejection, convergence rate, and operational precision. Practitioners should consider the algorithm’s potential to enhance the efficiency and reliability of bolt-tightening in high-altitude unmanned operations.