Improvement of step-climbing capability of a new mobile robot RHyMo via kineto-static analysis

This study presents the improvement of step-climbing capability of a new mobile robot called as RHyMo via kineto-static analysis. To this end, the kinematic analysis of the RHyMo is first performed to obtain the trajectory of its center of mass (CM) when it climbs up a step. Based on this CM trajectory, the linear/angular speeds and accelerations of its links are sequentially calculated. Different from the quasi-static analysis, the linear/angular accelerations are combined with the dynamic equations describing the force and moment equilibriums of RHyMo climbing the step, which are optimally solved by introducing the concept of the required friction coefficient in this study. This kineto-static analysis is repeatedly performed by changing the contact angle between the front track of RHyMo and the ground in order to minimize the torque required to climb the step. The simulations with different contact angles are carried out and then, the experiments using the RHyMo are performed, which can demonstrate that the trend of measured motor current is similar to that simulated by the kineto-static analysis and moreover, the step-climbing capability of the RHyMo is significantly improved by reducing the required motor currents by virtue of the kineto-static analysis.