Robust control of motion system and estimation of rider's action force for bicycle simulator

Abstract

A variety of vehicle simulators such as the automobile, flight, tank, motorcycle and ship simulators have been developed and are becoming widely used for testing of design, evaluation of environments, training for driving, entertainment and so on. Even though many investigators have studied various riding simulators, there are just a few works related to two-wheeled and human-powered simulators such as the bicycle simulator. One of the challenging problems with the bicycle simulator is to deal with the inherent unstable dynamics of the bicycle that is coupled with the human rider’s motion. Another is the real time simulation of human-controlled and powered vehicles moving in a virtual environment, including more realistic motion generation through a motion system. In this thesis, a six dof(degree of freedom) spring-supported Stewart platform was designed and used as a motion system for KAIST bicycle simulator. The spring support system was set up between the lower and upper platforms to compensate static load due to bicycle system, rider and so on. A sliding mode controller that is well known as model-based control strategy using only single PC processor is employed for high control performance for realistic motion feeling. For the model-based controller, the dynamic model of the spring-supported Stewart platform including actuator dynamics is derived by analytical and experimental methods. In analytical method, the principle of virtual work is used to formulate the dynamic equations of motion in order to increase the computational efficiency. In the derivation, the coordinates for the spring support system are different from the actuator coordinate system in order to avoid the formulation singularity. In experimental method, the dynamic parameters of the actuator such as a Coulomb friction, damping are measured, and verified by using load cell attached to the end of actuators. For the bicycle dynamics and the real time simulation, it is necessary to identify t...