Developing power-assisted two-wheeled luggage-carrying robot for stair-lifting using admittance control

We propose a control method for a two-wheeled robot that can carry a load in a staircase environment without increasing the burden on humans through power-assist control using admittance control. Considering that the motion of lifting the robot burdens a human in a staircase environment, it was necessary to reduce the peak value of the human force when pulling the robot upward. We evaluated the proposed, conventional, and the case without control (no control’’) methods by simulations and experiments on actual machines. Hence, the proposed method reduces the human workload to about 75% of that of the conventional method and about 50% of that without control. The proposed method can also enable the machine climb upstairs at a velocity of 1 step/s, which is about three times faster than the conventional method.