Electric braking control methods for electric vehicles with independently driven front and rear wheels

For electric vehicles (EVs), the most important issue is safety when driving and braking operations are performed. EVs with a structure that can drive the front and rear wheels independently have been proposed by the authors, and they are being studied as the next ECO vehicles. The basic fail-safe function has already been verified through simulations and experiments to provide stable driving without any sudden stops even when the elements constituting the driving systems fail. Then, methods to control phenomena occurring at the time of braking, which are uncontrollable only by driver's pedal operations, i.e., wheel lock, slip, and aggravation of the riding comfort, are studied here based on a prototype EV with a function that can distribute the braking torque to the front and rear wheels according to driving conditions. As a result, electric braking control methods using the estimated vehicle speed, acceleration, and load movement are proposed that can prevent vehicles from experiencing wheel lock and slip phenomena and can improve the riding comfort regardless of a driver's braking pedal operations. Effectiveness of the proposed methods is verified through experiments using the prototype EV.