On the Controllers Based on Time Delay Estimation for Robotic Manipulators
This addresses a critical flaw in control theory for robotics, ensuring reliable performance in applications with unmodeled dynamics, though it is incremental as it corrects and builds on existing methods.
The paper refutes a prior claim that a model-free controller with time delay estimation achieves asymptotic trajectory tracking for robotic manipulators under disturbances, showing the stability proof is incorrect, and presents modified controllers with rigorous proof.
Assurance of asymptotic trajectory tracking in robotic manipulators with a smooth control law in the presence of unmodeled dynamics or external disturbance is a challenging problem. Recently, it is asserted that it is achieved via a rigorous proof by designing a traditional model-free controller together with time delay estimation (TDE) such that neither dynamical parameters nor conservative assumptions on external disturbance are required. The purpose of this note is to show that this claim is not true and the stability proof of the method is incorrect. Finally, some modified versions of this controller with rigorous proof is presented for robotic manipulators.