Conceptual Design and Simulation of An Inverted Pendulum Wheelchair
The need to develop advanced wheelchairs especially for improving better mobility and comfort to help disabled people has led to an investigation into spherical inverted pendulum wheelchair concept. The wheelchair's concept is based around the dynamic and control of spherical inverted pendulum.The investigation starts with the stabilisation of the inverted pendulum using some various control strategies and command tracking capabilities also evaluated. Several different type control strategies are evaluated. These include (1) pole placement (2) PID and (3) Linear Quadratic Regulator (LQR). The stabilisation and tracking command performance of each control strategy is examined through simulation. The result shows all these three control strategies are capable to control the inverted pendulum system. But as the spherical inverted pendulum system is a MIMO system which has eight states and two inputs the LQR control strategy is more convenient to use for controlling the spherical inverted pendulum wheelchair.The dynamic equation for the spherical inverted pendulum wheelchair is presented and the modelling in SimMechanics also developed. The model is controlled by feedback control using LQR. The simulation shows that the body which represents the chair and the occupant is balanced on a spherical ball through four rollers (two driven and two idler) successfully. Thus the new wheelchair concept based upon the dynamic and control of spherical inverted pendulum has the potential to offer improved mobility compared with existing wheelchairs in the market place.
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