Stability of a wheelchair controlled by a human pilot

Wheelchair/pilot systems are extremely complex. A wheelchair/pilot model was developed to analyze stability for various dynamic situations. Several innovations are introduced here: human control of path and lean, a coordinate transformation approach to modeling the roadway, and the relationships of general dynamic to fixed dynamic analyses. Results show that fixed dynamic stability analyses are special cases of general dynamic analyses. The models incorporate human factors (physiology, psychology, anthropometry, and kinesiology), wheelchair design factors (frame and steering geometry), and environmental factors (road surface orientation and visibility). All of these factors affect performance and safety. Experimental data for pilot anthropometry and wheelchair design factors were collected. Systems with three and four wheels were simulated. Results show that both three- and four-wheeled systems can be stabilized with respect to path changes and disturbances under human control. Three-wheeled systems are shown to be more responsive, whereas four-wheeled systems are more stable