Fast passing over steps whose height is unknown by a 'variable structure type four-wheeled robot'

We are developing a wheeled robot called a 'variable structure type four-wheeled robot' which, with a simple structure, has ability to pass over a step. We already realized its dynamic passing over a step whose height is known. Therefore, in this paper, we propose a control method to pass over a step whose height is unknown. We mainly discuss the evaluation and planning method of a dynamic trajectory by considering the robot's stability against falling down in landing, and the control method to finish landing at a constant position on the step. We also confirm the possibility of detecting the height of the step by using the existing rotary encoder without adding any external sensors. As the result, we have successfully realized an experiment of this robot's going up steps whose height is unknown within only four seconds.