Human Control of a Bicycle

The bicycle, a simple toy to many, turns out to be an excellent platform to study the intricacies of vehicle dynamics, human-machine interaction, and human operator control for both academic and economical reasons. The bicycle is inherently unstable at low speeds and the human generally actuates the non-minimum phase system, and thus balances, only by means of rotating the handlebars. This dissertation describes a multi-year multi-person effort to better understand the dynamics of the bicycle, the biomechanics of the rider, and the rider's internal control system through theory and extensive experimentation. The chapters herein focus on the development of open loop bicycle models, some of which include the rider's biomechanics, the resulting predicted motion and model characteristics, the accurate measurement and estimation of both the bicycle and rider's physical parameters, observation of a rider's control motions, the development of experimental bicycles capable of measuring kinematics and forces, control theory including that of the human operator, and finally the identification of the both the plant and controller of the bicycle-rider system. The work has revealed a number of interesting conclusions including the primary biomechanic actuators used by the human in control, effects of the rider's motion and constraints on bicycle stability, the inadequacy of the Whipple bicycle model, and the ability of a simple multi-output control system based on the classical crossover model to describe the human's control efforts while being externally perturbed. These findings have implications in both single track vehicle design and human-machine interaction theory. Future applications may be able to utilize the methods and results to help objectively design bicycles with improved handling, stability, and controllability whereas human operator research may be able to build on the validated crossover model theory of manual control.