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The development of an integrated controller for a 4WS/4WD electric bus is investigated. The front wheel steering angle is assumed to be controlled by the human driver. The vehicle is controlled by the rear wheel steering and the yaw moment that can be generated by the differential torque/brake control on each wheel. The high speed cornering is used as the testing scenario to validate the designed controller. Due to the highly nonlinear and the multiple-input and multiple-output nature, the control design is separated into different stages using the hierarchical layer control concept. The longitudinal speed is controlled using a PI controller together with a rule-based speed modification. The other two control inputs, namely the rear wheel steering and the DYC moment, are then designed using the state-dependent Riccati equation method. The designed controllers are evaluated using computer simulations first, and the simulations showed promising results.

The purposes of this study are to 1) select a suitable size of dual energy sources, 2) develop a dynamic model for a battery/supercapacitor (SC) electric bus with an integrated fast charger/bus stop station, and 3) establish control strategies among the fast charger, batteries, and the SC module. For 1), a global search method was used to locate a suitable-sized battery set and SCs under a preset cost function and basic properties. The cost ratio (CR) was calculated to maximize the energy storage capacity. For 2), 10 subsystems of the electric bus, including the driver maneuver, traction motor, the lithium battery module, the SCs, the onboard DC/DC converter, the longitudinal vehicle dynamics, accessories, and the transmission were constructed. For the fast charger/bus stop station, an AC/DC inverter was modeled. All modulized subsystems were then integrated into the vehicle/station simulator.