| Manual wheelchair propulsion generates a high and repeated load on the shoulders, and eventually causes chronic shoulder pain to near half of the users. A small improvement of the propulsion efficiency could decrease the risk of long term shoulder pain. Training sessions were previously attempted, where a visual biofeedback was presented to subjects in order to improve their propulsion efficiency. However, these sessions led to mixed results. Based on recent advances in robot-assisted rehabilitation, we hypothesize that a haptic biofeedback would be more suited than a visual biofeedback to induce a change of force direction in the users' propulsion pattern. The topic of this thesis is the development of a manual wheelchair simulator that provides a haptic biofeedback to the users to redirect their force direction patterns toward a desired pattern.;A caster wheels orientation estimator is first developed and presented. This estimator allows to model the orientation of the rolling resistance forces. Its precision is of +/-5° to +/-8° depending on the wheelchair trajectory. Second, a dynamic model of the wheelchair and an identification method for its three parameters are developed and validated with 10 subjects. Compared to the model of a standard roller ergometer, this new model estimates the rear wheels velocity with near half the error, with root-mean-square (RMS) velocity errors of 6% to 13% depending on the wheelchair trajectory. Third, a manual wheelchair simulator is implemented as a haptic interface based on an admittance command. This simulator reproduces the presented dynamic model of the wheelchair with a RMS velocity error of less than 0.9%. Finally, a preliminary haptic biofeedback experiment is realized with one pilot subject. The haptic biofeedback allowed to increase the subject's propulsion efficiency by 10%.;The simulator presented in this thesis will be a tool of choice, in a first time to study the real impact on the shoulder of different force direction patterns, and will contribute to extend the knowledge on the best wheelchair propulsion techniques. Later, this simulator will allow to train wheelchair users to use an optimal propulsion technique, in the aim of reducing the risk of developing chronic shoulder pain.;Keywords: Wheelchairs, Simulators, Ergometers, Biofeedback, Haptic interfaces, Real time systems, Robotics, System modelling, Observers, Stability. |
