Scientists at TUM developed a wheelchair that can climb stairs. (Credit: Uli Benz/TUM)

People confined to a wheelchair are still confronted with insurmountable obstacles in everyday life – even in today’s more wheelchair-accessible society. While there are already wheelchairs that can climb stairs, they can still tip over. Researchers have developed a stairclimbing wheelchair that can stabilize itself. It is part of a larger mobility concept that enables wheelchair users to move independently for short and medium distances.

In contrast to a two-axle wheelchair chassis, this wheelchair can move forward and backward and rotate around its own axis almost simultaneously. The wheelchair holds itself up according to the inverted pendulum principle. Two "feet" that have a similar configuration to human legs — with an upper and lower leg — are attached to the wheelchair.

If the chair’s ultrasonic sensors detect stairs in the path of travel, the wheelchair reverses itself with its back to the stairs until the two wheels have physical contact with the first stair. Then the "feet" are extended, and the wheelchair lifts itself up the step. Powered by an electric motor, the legs push the wheelchair to the next higher step. A camera system monitors the “staircase topography” to ensure that the wheelchair is firmly on a step and not, for example, on the edge.