Model-based control for an innovative power-assisted bicycle

This paper presents an activity concerning the development of a control strategy for power-assisted electric bicycles, also called pedelecs. A common assistance algorithm available on commercial pedelecs consists in providing predefined constant assistance electric power. This approach is lack of flexibility with respect to environmental condition and generally does not provide a good driving comfort. The proposed control method has been designed to minimize the tracking error between the actual bike velocity and the desired one, in the presence of external disturbances. The assistance electric motor torque consists of a feedforward torque integrated with a feedback one. The feedforward contribution is a nonlinear torque based on the pedelec model. The feedback action has the function to compensate the tracking error due to model uncertainties and unknown disturbances. The performance of the methodology has been evaluated applying the controller to an innovative pedelec prototype. To this aim, a mathematical model of the vehicle has been developed. Different human torque models have been implemented in order to study the influence of the rider on the pedelec dynamics. The results of a comparative analysis between the proposed algorithm and a common assistance method have demonstrated that the proposed controller provides improvements in terms of riding comfort and energy utilization.