Driving force control method for front-and-rear-wheel-independent-drive-type electric vehicles (FRID EVs) effective for safe driving under various road conditions

A driving force control method suitable for front-and-rear-wheel-independent-drive-type electric vehicles (FRID EVs) is described. This method can prevent the occurrence of wheel slip while driving on dangerous roads having a low-mu surface. The method can distribute the driving and braking torque to the front and rear wheels depending on the driving conditions of the vehicle and road conditions. Generally, while accelerating, there is a load movement from the front end to the rear end of the vehicle. Since a load moves to the rear wheels, rear wheels easily cause a wheel spin to induce slip when running bad roads if driving torque is distributed to rear-wheels according to the load movement. The driving force control method proposed here prevents wheel lock by properly distributing the driving torque to the rear wheels using the tire-road friction coefficient estimated from the information obtained during the slip control of the front wheel. The effectiveness of the proposed driving control method to prevent wheel slip while distributing the driving force between the front and rear wheels is verified through simulations performed under various low mu road conditions.