Robust Adaptive PID Control Based on a Modified Nussbaum Function for Robots Exposed to Significant Changes in Dynamics

Proportional-integral-derivative (PID) equipp-ed controllers are widely used in industrial robots potentially facing substantial payload and environmental variations. Their widespread use may impede the implementation of advanced robust control methods. This study presents a robust adaptive PID control algorithm that is model-independent, simple, and suitable for deployment on commercial PID-equipped devices. The proposed adaptive PID control is based on a modified version of adaptive time-delay control employing modified Nussbaum functions to ensure stability under substantial variations of robot and environment dynamics, and includes straightforward gain drift prevention schemes. The performance of the proposed adaptive PID control was experimentally evaluated with other PID controls and advanced model-independent control, showing enhanced robustness and no gain drift. These results demonstrate the potential of the proposed PID control for immediate deployment in industrial robots with a PID-equipped controller.