Steering dynamic model and driving strategy of variable-configuration wheel-tracked unmanned ground vehicles by considering terramechanics

The variable-configuration wheel-track unmanned ground vehicle (VCWT-UGV) can adapt to complex environments with advantages of high maneuverability and strong passing ability. The analysis of steering dynamics characteristics is the theoretical basis to ensure UGVs can still maintain high maneuverability in different environments. This article proposes a universal steering dynamic modeling for UGVs and an efficient driving strategy suitable for VCWT-UGV, starting from requirements of analyzing steering dynamics characteristics. Firstly, based on the operation environments and the characteristics of the wheel-track composite locomotion mechanism (WTCLM), the normal balance during steady-state steering process on soft soil is established; Secondly, based on the model, the steering dynamics characteristics of traditional three axle-wheeled UGV and VCWT-UGV were compared; Then, the optimal driving strategy is designed combined with the analysis results based on the motion mode and driving configuration. Finally, the simulation and test results demonstrate the accuracy of the model and the feasibility of strategies. The combination of wheel-track and variable-configuration can significantly improve the lateral mobility. Under the premise of maintaining the same driving configuration, by adjusting the moving mode, the critical load for slip has been increased by 40%, the sinkage depth has been reduced by 33% and the traction has been increased by 16.8%. In addition, considering the steering path and time, without changing the differential input, the steering radius is increased or decreased by 16.7% by adjusting the driving configuration, and the corresponding steering time is also optimized. The research results provide valuable references for the general dynamic modeling methods of UGVs.