Adaptive Active Compliance Control for Wheel-Legged Vehicles on Uneven Roads Based on a Parallel Integrated Framework

As a novel all-terrain vehicle, the wheel-legged vehicle (WLV) has potential advantages in high-speed maneuverability on rough terrain. However, due to the complexity of dynamically coordinating wheel and leg motion, the integrated control of speed stability and sprung mass compliance faces challenges. Based on the vertical-longitudinal (VI) coupled dynamic characteristics of WLVs, and considering the transmission mechanism and interaction of VI forces at wheel-end, a novel parallel integrated control framework (PICF) for WLVs is proposed. By separating the compliance control of vertical, pitch and longitudinal velocity in the PICF, the controller dimension and solution complexity are reduced. Then, ignoring the rotational dynamics of the two-link in WLV, simplified VI half-body models are established respectively. Combining virtual model control (VMC) theory and linear quadratic regulator (LQR) knowledge, we propose an adaptive active compliance controller (AACC). By coupling the VMC and LQR forces, the AACC achieves optimal compliance control and road adaptability similar to active suspension systems (ASS). Finally, simulation results indicate that the proposed AACC with the PICF under speed bump road can not only improve speed stability, but also significantly reduce vibration in the time and frequency domain, with pitch angle values below 0.02.