Adaptive‐Based Non‐Singular Terminal Sliding Mode Control of a Three DOF Spatial Robotic Manipulator

摘要

ABSTRACT In this paper, a non‐singular terminal sliding mode controller based on the adaptive technique is proposed to realize high‐precision control of a spatial three‐degree‐of‐freedom robotic arm under strong disturbances. Firstly, to ensure that the trajectory tracking error can converge to zero in finite time and to avoid the singularity problem in the control law, a control law containing an inverse tangent function is chosen. Secondly, the chattering phenomenon is eliminated by introducing the boundary layer technique. In addition, the adaptive technique is introduced to greatly improve the disturbance rejection capability of the controller while retaining the advantages of the original sliding mode surface, and the drift problem of the adaptive law is solved by introducing the dead‐zone correction term. Based on the Lyapunov theory, the finite‐time convergence of the system is proved, and a simulation platform and a physical experimental setup are built to physically verify the controller. Taking the IAE of the tracking process in the first joint as an example, the proposed controller improves tracking accuracy by 73%, 66%, and 34% compared to non‐singular terminal sliding mode controller (NTSMC), inverse tangent‐based non‐singular terminal sliding mode controller (ATNTSMC), and adaptive robust non‐singular fast terminal sliding mode controller (ARNFTSMC), respectively. Additionally, the proposed methodology achieves the fastest convergence rate, with improvements of 55%, 45%, and 29% over NTSMC, ATNTSMC, and ARNFTSMC, respectively. These results demonstrate the significant potential of the proposed methodology in enhancing the robustness, accuracy, and applicability of robotic systems.