Fast Finite-Time Sliding Mode Control for Chattering-Free Trajectory Tracking of Robotic Manipulators
Momammad Ali Ranjbar
TL;DR
The paper tackles robust, high-precision trajectory tracking for a 3-DOF robotic arm under uncertainties and chattering in sliding mode controllers. It develops a chattering-free fast terminal sliding mode control (FTSMC) in a state-space framework, introducing sliding surface $S_1 = \dot{e}_1 + \alpha e_1 + \beta e_1^{\frac{p}{q}}$ and a Lyapunov-based finite-time stability analysis. The control law combines an equivalent component with a switching term and is validated against PD-SMC and TSMC through simulations on the 3-DOF arm model described by $M(\theta)\ddot{\theta} + C(\theta,\dot{\theta}) + G(\theta) = \tau$, showing faster convergence, higher accuracy, and robustness to disturbances. Hyperbolic tangent switching reduces chattering while preserving performance, indicating practical applicability for high-precision robotic applications. The results suggest significant potential for deployment in industry, enabling faster, smoother, and more reliable torque commands in robotic manipulators.
Abstract
Achieving precise and efficient trajectory tracking in robotic arms remains a key challenge due to system uncertainties and chattering effects in conventional sliding mode control (SMC). This paper presents a chattering-free fast terminal sliding mode control (FTSMC) strategy for a three-degree-of-freedom (3-DOF) robotic arm, designed to enhance tracking accuracy and robustness while ensuring finite-time convergence. The control framework is developed using Newton-Euler dynamics, followed by a state-space representation that captures the system's angular position and velocity. By incorporating an improved sliding surface and a Lyapunov-based stability analysis, the proposed FTSMC effectively mitigates chattering while preserving the advantages of SMC, such as fast response and strong disturbance rejection. The controller's performance is rigorously evaluated through comparisons with conventional PD sliding mode control (PDSMC) and terminal sliding mode control (TSMC). Simulation results demonstrate that the proposed approach achieves superior trajectory tracking performance, faster convergence, and enhanced stability compared to existing methods, making it a promising solution for high-precision robotic applications.