Adaptive Terminal Control of n-DOF Robot Manipulators With Enhanced Nonlinear Model-Based Synergetic Manifold

Abstract

This paper presents an Adaptive Terminal Model-Based Synergetic Control (ATMB-SC) framework for n-DOF robot manipulators, addressing critical limitations of conventional synergetic control. The proposed strategy integrates a nonlinear model-based manifold function for robotic manipulators, ensuring robust trajectory tracking while eliminating the coupling effect inherent in the conventional synergetic control method. By establishing a linear relationship between the torque input and both position error and its rate of change, the method simplifies control design without compromising robustness or accuracy. An adaptive strategy based on the MIT rule dynamically adjusts the convergence matrix in real-time is implemented, enhancing precision and responsiveness to uncertainties and external disturbances. Additionally, a terminal term is incorporated into the manifold, guaranteeing finite-time convergence of error trajectories, which is critical for high-precision, time-sensitive applications. Experimental validation on a 4-DOF robot demonstrates the strategy’s effectiveness, with input torque variation improved by 10% to 112.67% and the least mean square error achieved across all axes, ranging from 1.63<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</i> − 4 to 9.15<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</i> − 5, compared to other controllers.