Fixed-time fuzzy disturbance observer based distributed control of uncertain cooperative manipulation under composite disturbances

Abstract

This article addresses the distributed control of cooperative manipulators under unknown composite disturbances via a fixed-time fuzzy-observer-based approach. First, a unified dynamic model is established for distributed task execution. Then, a fixed-time distributed trajectory observer is designed for each manipulator to reconstruct the object’s pose, velocity, and acceleration. Moreover, fixed-time position and force controllers are developed using the observed states and the model to ensure trajectory tracking and synchronization. Finally, simulations on a cooperative system with four 6-DOF UR5 manipulators using a MATLAB/CoppeliaSim platform validate the proposed approach. The results demonstrate that: (1) the fixed-time distributed estimators converge within 0.08 seconds; (2) the proposed hybrid controller achieves high-precision tracking with position errors below 0.0015 m and force errors below 8 N; (3) compared to existing finite-time control methods, the proposed approach reduces convergence time by approximately 50% and significantly improves steady-state accuracy.