Fig. 1
In conventional, differentially steered manual wheelchairs (left), a turn around an instantaneous Centre of Rotation (CoR) is induced by positive power (green) input on the curve-outer side (PO) and simultaneous braking (red) on the curve-inner side (PI) whereby the front wheels simply follow the movement thanks to a small trail distance (T). The location of the Centre of Mass (CoM, CoM’) forward of the rear axis increases the moment of inertia against turning and affects directional stability on tilted surfaces such as pavements. Our steering-by-leaning system (right) uses the tilting angle (β) of the backrest to steer the front wheels by corresponding angles δI and δO and therefore allows movement direction to be changed without braking