Adaptive Cascade PID Control of Robot Manipulators with Unknown Loads and Disturbances

Adaptive PID control plays an important role in trajectory tracking of robot manipulators. However, most theoretical researches on adaptive control exhibit certain discrepancies when applied to the practical robotic servo control system. This paper introduces a novel industrial-grade cascade adaptive Proportional-Proportional-Integral (PPI) controller based on a detailed analysis of the traditional PPI control architecture. Through rigorous Lyapunov stability analysis, the proposed adaptive PPI controller is proven to guarantee the asymptotic convergence of manipulator joint trajectory tracking errors to zero. Furthermore, it exhibits superior robustness against unknown loads and disturbances compared to classical PPI controllers and adaptive PD controllers. Extensive simulation studies and comparative analyses with scara robot manipulators validate the effectiveness and superiority of the proposed controller.