This paper proposes a control method for semi-autonomous stair climbing using an articulated mobile robot. Stair-climbing motion is achieved by propagating a single backward wave along the body of the robot. The robot moves forward by shifting a part of the body lifted from the step (the elongating part) from front to back. Semi-autonomous stair climbing is accomplished by automatically determining when to shift the elongating part backward based on the relative position between the step and the robot. Furthermore, we developed an actual robot that can measure the relative position between itself and the environment to climb stairs semi-autonomously. The developed robot is equipped with several short-range sensors on the lower part of its body, which can measure the relative distance between the robot and the stair tread surface. The effectiveness of the proposed control method was verified by simulations using a physics simulator and by experiments with the developed robot.

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