RISE-Based Actor–Critic Control for a Four-Wheeled Mecanum Robot with Center-of-Mass Offset

This paper presents a RISE-based Actor–Critic control scheme for a four-wheeled Mecanum mobile robot subject to manipulator-induced center-of-mass (COM) offset and dynamic uncertainties. The COM deviation is explicitly modeled, leading to nonuniform wheel loading and wheel-dependent slipping. By transforming the time-varying tracking problem into an autonomous affine system, an online Actor–Critic algorithm with a discounted cost function is developed to achieve optimal trajectory tracking. A multi-channel RISE feedback term is integrated to compensate COM-induced and slip-related disturbances without requiring persistent excitation. Lyapunov analysis guarantees uniformly ultimately bounded closed-loop behavior, and simulation results demonstrate improved tracking accuracy and robustness under time-varying COM offsets.