Study of Rocker-Bogie typed Mobile Robot for Driving, Climbing and Standing Upright

This paper studies a mobile platform system to provide a service for a large range of regions. The coverage of large service region is recently required while the service robot market is rapidly increased. Therefore, Regions of delivery/patrol/surveillance/inspection services started to include outdoor terrains as well as indoor environments. Therefore, mobile robots have to adapt uneven terrains and overcome obstacles. In this paper, we introduce a rocker-bogie typed mobile robot which is able to provide this required capability. The robot has six active driving wheels, two degrees of freedom (DoFs) for active steering, and 2 DoFs for active bogie. The linear dynamic model was derived, and practically the values for normal and traction forces are calculated through the simple pseudo-inverse technique. The compensation algorithm is added to achieve minimal friction on the bogie axis, which leads to all wheel contact with the ground through the adaptation to uneven terrains. Also, the calculated traction force is distributed to ground contact wheels based on sensor estimation. In the experiment, upright-standing and climbing a curb were demonstrated. Especially, the upright posture of the robot was verified to be controlled based on Linear Quadratic Regulator (LQR) optimization controller using inverted pendulum model.