A theoretical control method for a fixed-time all-drive system with state constraints for a robotic arm

By combining nonlinear transformation and fixed-time sliding mode control with radial basis function adaptive law to optimize controller gain, the complexity and constraints of robotic arm joint angle tracking control are solved, achieving fast, stable, and high-precision tracking results.

CN121223768BActive Publication Date: 2026-05-26SICHUAN UNIV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
SICHUAN UNIV
Filing Date
2025-09-17
Publication Date
2026-05-26

AI Technical Summary

Technical Problem

Existing robotic arm joint angle tracking control methods suffer from design complexity, differential explosion problem, limited convergence performance, difficulty in handling state constraints, and challenges in controller gain tuning, making it difficult to achieve high-precision, fast, and stable tracking control under unmodeled dynamics and external disturbances.

Method used

A nonlinear transformation function is used to map joint angle constraints to an unconstrained transformation variable space. A fixed-time controller is designed by combining fixed-time sliding mode control and radial basis function adaptive law. The controller gain is optimized by the optimal control problem, and an all-drive system model is constructed to handle unknown disturbances and constraints.

Benefits of technology

It achieves rapid convergence within a finite time, online compensation for unmodeled dynamics and external disturbances, simplifies controller design, improves the tracking accuracy and robustness of the robotic arm joint angle, reduces computational complexity, and is suitable for multi-degree-of-freedom robotic arm systems.

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Abstract

This invention discloses a theoretical control method for a fixed-time all-drive system with state constraints for a robotic arm, belonging to the field of robotic arm joint tracking control technology. The method includes: establishing a standard model of an n-degree-of-freedom robotic arm all-drive system, and processing preset joint angle constraints using a nonlinear transformation function to obtain an all-drive system model with respect to the transformation tracking error variable; constructing a fixed-time sliding mode function with respect to the transformation tracking error variable; using radial basis functions to process uncertainties and external disturbances in the control system, and designing a fixed-time controller and corresponding adaptive law based on all-drive system theory; and transforming the optimal gain selection problem of the fixed-time controller into an optimal control problem using a control parameterization method, and obtaining the optimal controller gain by solving this optimal control problem. This invention enables fast, high-precision, and highly robust trajectory tracking control under joint angle constraints.
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