Fixed-time inter-axis synchronisation control of multi-manipulator systems under switching topologies

This article proposes a fixed-time inter-axis synchronisation control method based on a distributed observer for multi-manipulator systems subject to external disturbances under switching topologies. First, a distributed fixed-time observer (DFTO) is developed to estimate the state information of the leader manipulator, and the fixed-time convergence is rigorously proven for fixed and switching topologies. Then, a fixed-time inter-axis synchronisation controller is designed to address the joint state tracking problem for follower manipulators to reach consensus with the leader, while also avoids singularity issues associated with the traditional terminal sliding mode control (SMC). Furthermore, the proposed controller realizes the inter-axis coordination of each manipulator by ensuring the convergence of inter-axis synchronisation errors through a cross-coupled control approach. Finally, simulations conducted on one leader manipulator and five follower manipulators validate the proposed method, demonstrating its effectiveness in achieving fixed-time inter-axis synchronisation under switching topologies with high robustness and precision.