Model-Free Sliding Mode Control Using Time-Delay Estimation and Adaptive Technique Applied to Manipulators ^*

This paper synthesizes a novel robust controller tailored for industrial robot arms, seamlessly integrating sliding mode control (SMC), adaptive techniques, and time-delay estimation (TDE). Leveraging TDE, our controller adeptly estimates both the inherent dynamics of the robot and unstructured uncertainties like disturbances and parameter variations. However, since TDE relies on past angular acceleration and input torque, it inevitably introduces errors. To tackle this, our approach compensates for current TDE errors using past TDE error information. By considering value of the current updating parameters and the sampling time, an adaptive law has been proposed to ensure the positivity of these parameters and the chattering control signals. Through extensive simulated studies conducted on industrial robot manipulators, we demonstrate the effectiveness of our control approach, showcasing robustness, reduced chattering, and high accuracy across diverse scenarios.