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

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.