Modelación matemática y simulación del sistema mecánico de una silla de ruedas bipedestadora usando el método de Bond-Graph

Abstract

The objective of this project was to define a mathematical model and perform the simulation of the mechanical system of a standing wheelchair using the Bond - Graph method; taking as critical positions of analysis: seated (chair) and standing (upright). The simulation process started from the definition of the dimensional parameters for each element of the chair as indicated in the ISO 21542: 2012 Standard and the operating parameters of the electrical components were established, for the electric motor a nominal speed of 70 RPM considering that the translation of the person is carried out from rest in a horizontal and inclined plane; while, for the actuator, seated position was considered a critical stage and a thrust of 1500 N was defined. Then, a dynamic, static, velocity and acceleration analysis was carried out for each component of the system, and critical loads, angular velocities were defined, inertia and points of interest for the simulation; where applying the Bon Graph method, the mathematical model that governs the movement of each element of the mechanism was defined and the variation curves for the position and displacement of the standing chair were obtained. These showed that a height of 1.15 m is reached, and verticality is maintained during the movement, which physically guarantees the free and safe movement of the user when he changes position from seated to bipedal. It is concluded that the Bond Graph method allows the direct control of the mobility parameters (velocity, acceleration) through the variation of external parameters (mass, inertia, angles) to obtain a translational and rotational movement of the body. Finally, it is recommended to use software programs with graphical interfaces that are easy to interpret and that allow a better simulation of the general model.