A three-dimensional (3-D) inverse dynamic model of wheelchair propulsion was developed using the Newton-Euler method based on body coordinate systems. With this model, the arm was assumed to be three rigid segments (hand, forearm, and upper arm) connected by the wrist, elbow, and shoulder joints. A symbolic method was adopted to generate the equations of motion. The model was used to compute the joint forces and moments based on the inputs obtained from a 3-D motion analysis system, which included an instrumented wheelchair, video cameras, and a data acquisition system. The linear displacements of markers placed on the joints were measured and differentiated to obtain their velocities and accelerations. Three-dimensional contact forces and moments from hand to handrim were measured and used to calculate joint forces and moments of the segments.
Mary M. Rodgers is with the Department of Physical Therapy, University of Maryland, 100 Penn St., Baltimore, MD 21201-1082. Srinivas Tummarakota is with Automated Analysis Corporation, 423 S.W. Washington, Peoria, IL 26160. Junghsen Lieh is with the Department of Mechanical and Materials Engineering, Wright State University, Dayton, OH 45435.