Optimal charging and speed control of electric buses based on traffic flow predictions

This paper deals with electric and autonomous buses that have to follow a given route in extra-urban roads, with a given timetable for reaching the stops. All the stops are provided with a charging infrastructure allowing to charge the batteries when buses are present at stops. We propose a real-time control algorithm which computes the optimal speed of buses along the route and the charging times at stops. Since the trajectories of buses are affected by the traffic conditions, the proposed control algorithm is based on a prediction module in which a traffic model is run periodically to predict the traffic state in the road network. Thanks to this model, the average speed of the traffic flow in the different road sections is predicted and used as upper bound of the bus speed. The proposed control algorithm is based on the solution of an optimal control problem in which the cost function jointly minimizes the deviations of the stopping times from those defined in the timetable and the deviations of the final energy of the bus batteries from a desired value. Simulation results based on a real case show the trade-off between these objectives.