A Lyapunov-Based Step-by-Step Sliding-Mode Observer Algorithm With Application to Joint Torque Estimation of Robot Manipulators

Yongzheng Cong, Haibo Du, Weile Chen, Wenwu Zhu, Guanghui Wen

Abstract: Force control strategies are crucial for robot manipulators to effectively adapt to diverse tasks. However, employing force sensors to measure force/torque information significantly increases the cost of robotic systems. Hence, it is crucial to delve into sensorless force/torque estimation techniques. Given the low precision of traditional force estimation algorithms, this article presents a novel algorithm to improve the torque estimation precision of robot manipulators' joints. First, based on the dynamic model, a finite-time sliding-mode torque observer is designed for the robot manipulators via a step-by-step method. A new Lyapunov function is constructed to prove the finite-time convergence of the closed-loop system. Second, in the presence of sampling noise, the robustness of the proposed finite-time torque observer is analyzed. Finally, simulation and experimental results validate the effectiveness of the proposed algorithm.