Real-World Application of Variable Pedal Feeling Using an Electric Brake Booster with Two Motors (SAE Paper 2020-01-1645)

Abstract

A new type of electric brake booster, which can control brake pedal feeling completely with software, has been developed to explore how a brake system can be used to differentiate and personalize vehicles. In the future, vehicles may share an increasing amount of hardware and rely more heavily on software to differentiate between models. Car sharing, vehicle subscriptions, and other new business models may create a new emphasis on the personalization of vehicles that may be achieved most cost effectively by using software. This new brake booster controls the brake pedal force and brake pressure independently based on the brake pedal stroke so that the pedal feeling is completely defined by software. The booster uses two electric motors and one master cylinder. One electric motor controls the pedal force and provides an assist force that amplifies the force that the driver applies to the brake pedal. The second electric motor moves the master cylinder piston independently of the brake pedal stroke and is used to control the brake pressure. To confirm the real-world feasibility of this concept, the booster was installed in an actual vehicle. The evaluation of this vehicle confirmed that software-defined pedal feeling is feasible to implement in a real vehicle. Pedal feeling as good as that of a mass produced vehicle could be achieved, and the pedal feeling could be quickly and easily changed without the time and expense required to change brake hardware. Additionally, using this new booster, new types of pedal feeling that are not possible to achieve on a conventional vacuum booster vehicle could be easily implemented with software.