The Coordinated Control Strategy of Wheel-Tracked Driving Force Allocation Based on Hierarchical Theory

The wheel-tracked hybrid vehicle, as an innovative configuration integrating both wheels and tracks, exhibits significant advantages in driving adaptability and terrain handling compared to conventional single-mode wheeled or tracked vehicles. However, the multi-drive component architecture introduces substantial challenges in control coordination. This study proposes a novel hierarchical control-based coordinated driving force distribution strategy to address the coupling and coordination problem among diverse drive components in wheel-tracked hybrid vehicles. First, a compound speed controller combining feedforward and feedback mechanisms is designed to accurately compute the total driving force based on desired speed objectives. Then, an energy-optimal allocation layer is constructed, in which a cost function incorporating both slip ratio deviation and energy loss is formulated. The optimal wheel-track slip ratios are derived using the Lagrange multiplier method, enabling energy-efficient force distribution. Finally, a sliding mode control (SMC)-based optimal slip ratio controller is developed to precisely regulate driving torque and ensure tracking of the optimal slip ratio. The proposed method distinguishes itself from existing approaches by integrating multi-level control with energy optimization and robustness against nonlinearities and uncertainties. Simulation results show that, compared to conventional equal distribution strategies, the proposed approach reduces energy loss by 15%, demonstrating its superior energy efficiency and coordinated control performance. These findings highlight the effectiveness and novelty of the presented strategy in advancing intelligent control for complex hybrid drive systems.