Wheelchair.q, a motorized wheelchair with stair climbing ability

The paper deals with Wheelchair.q, a concept for a stair climbing wheelchair capable of moving in structured and unstructured environments, climbing over obstacles and going up and down stairs. The design of the wheelchair, consisting of a frame, a seat and a four-bar linkage mechanism that connects frame and seat, is presented. The four-bar linkage moves and rotates the chair to prevent the wheelchair from overturning and to guarantee a comfortable posture to the passenger during different operations. The kinematic synthesis of the linkage mechanism is discussed using an algebraic method. When the wheelchair faces an obstacle such as a step or a stair, it can passively change locomotion mode, from rolling on wheels to walking on rotating legs, thanks to its self-adaptive locomotion units. The function of the locomotion unit is described and modeled using kinematic equations. The locomotion unit requires only one motor, for both wheeled and legged locomotion. Tests on a scale prototype were conducted in order to evaluate the effectiveness of this locomotion.