Investigation of a quasi-static wheel-ground contact sensor for off-road vehicles

A 6-axis wheel force/torque sensor was developed to provide contact forces and the effective contact point between the wheels of an off-road vehicle and the terrain. When the vehicle traverses harsh terrain conditions, the location of the effective contact point as well as the magnitude of the contact forces are important in estimating the load distribution in the system. Here analytical models were developed to determine effective contact point between wheel and the terrain. Error analyses to estimate errors in the effective contact point, due to the force/torque sensing errors were performed. A comparison of the effective contact point obtained from simulation results and the experimental results showed the feasibility of the wheel force/torque sensor to calculate the effective contact point. As an application of the designed sensor, energy based tip-over stability analysis for off-road vehicles was investigated. A comparison of Energy Stability Margin (ESM) between a vehicle that possesses force sensing to compute accurate effective contact point versus one that possesses no force sensing was presented. The comparison showed that for harsh terrain conditions the resulting errors in the ESM were as high as 80%. Error analysis for the vehicle stability analysis was also performed to verify that the robustness of the suggested stability analysis for off-road vehicles.