Fast passing over steps with unknown height 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. In this paper, we consider the control of dynamic passing over steps whose height is unknown. We propose a method for planning a dynamic trajectory by evaluating the robot's stability against falling down in landing. We also confirm the possibility of detecting the height of the step 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.