Maneuverability Analysis of Front Drive Type Personal Vehicle STAVi using Modeling Error Compensation System

Abstract

Electric-powered personal vehicles have been used as a convenient transport device. Therefore, a front-drive-type personal vehicle STAVi, that is easy for elderly but also disabled persons, to climb on from a bed has been focused on. However, front-drive-type personal vehicles are difficult to operate because their over-steering characteristic is strong owing to free casters. If the vehicle can be driven by an easy joystick operation, it will be a comfortable function for all users. STAVi prototype had been developed for driving in hospitals with slow speed drive. However, we sometimes drive STAVi in many places with ordinary speed as a personal vehicle. For personal vehicle, it is well known that under-steer characteristic is required to drive even though the vehicle is front-drive-type. In this paper, we construct a control system for STAVi using a modeling error compensator with a nonlinear reference model to realize a comfortable under-steer characteristics. The advantage of proposed controller is discussed and it is clarified that the over-steering characteristic can be modified to be under-steering one. By using proposed method, the maneuverability can be improved for front-drive-type vehicle STAVi and its joystick operation is evaluated by phase-plane analysis.