Accurate estimation of drawbar pull of wheeled mobile robots traversing sandy terrain using built-in force sensor array wheel

The wheels of planetary rovers that are used in space explorations sometimes slip or lose contact with the ground while traversing a sandy terrain. In order to estimate the behavior of these rovers moving on loose soil, it is very important to accurately estimate the drawbar pull of their wheels. Some wheel-soil interaction models based on terramechanics have been proposed for the estimation of the normal stress distribution and drawbar pull of such rovers. However, our experimental results (normal stress distributions are directly measured using a pressure sensor array, which is attached to the wheels of a rover) show that the distribution range of normal stress for small wheeled rovers obtained using the proposed method is considerably smaller than that obtained by using conventional method. Consequently, the drawbar pull estimated using conventional methods is inaccurate. Therefore, in this study, the normal stress distribution is directly measured using pressure sensors in order to estimate drawbar pull accurately. From the data obtained using the sensors, a soil parameter, which is generally very difficult to measure, is estimated. Then, the drawbar pull is estimated using this parameter. The drawbar pull estimated by using the proposed method is more accurate than that estimated using conventional methods. In this study, we propose a new method for the estimation of drawbar pull and also validate this method.