New fixed-time control achieves precise tip positioning for flexible robot arms

A team of researchers from India (Atul Sharma, Chayan Kumar Paul, and S. Janardhanan) has published a new control strategy for flexible manipulators, a common challenge in robotics where link flexibility causes positioning errors. Their paper introduces an observer-based fixed-time nested sliding-mode control that guarantees precise tip-position regulation within a predetermined time, regardless of initial conditions.

The core innovation is a nested non-singular terminal sliding mode controller that provides robustness against disturbances and model uncertainties, paired with a fixed-time sliding mode observer that estimates unmeasured system states accurately within a guaranteed convergence time. This eliminates the need for additional sensors while enabling closed-loop control. The team validated their approach through both numerical simulations and experiments on a real hardware setup, demonstrating superior accuracy, stability, and convergence speed compared to existing methods.