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.

No abstract

The application of light materials to space structures, aircraft, robots and automobiles has increased the demand for effective algorithms to model and predict the response of structural multibody systems. The understanding of mechanics can assist in developing better design and control strategies. Formulation of mathematical models of a multibody system using manual approaches is a difficult task and prone to errors. For non-linear and/or time-varying systems, numerical formulation provides limited information about physical insight. In this study, a computer-aided symbolic method is used to generate the equations of motion from Lagrange's method. Equations are converted into FORTRAN form ready for simulations and control synthesis. The 4-5th order RungeKutta-Fehlberg method (RKF45) was used to numerically solve the system of equations. Two examples, namely a slider-crank mechanism and an aircraft model are presented.