US Patent 10391990 Vehicle braking system and method of operating the same

A vehicle braking system includes a wheel cylinder, a master cylinder, a brake pedal operable to transmit a user input force to the master cylinder, a primary braking unit including a first electronically controlled pressure generating unit distinct from the master cylinder and operable to generate a braking force at the wheel cylinder in a first mode of operation, a secondary braking unit including a second electronically controlled pressure generating unit distinct from the master cylinder and operable to generate a braking force at the wheel cylinder in a second mode of operation and a pedal feel simulator operable to provide feedback to the brake pedal according to a fixed characteristic of the pedal feel simulator defining a predetermined force-stroke relationship relating a travel distance of the brake pedal to the user input force. In the first mode of operation, the secondary braking unit is operable to receive fluid from the master cylinder to diverge from the predetermined force-stroke relationship at the brake pedal.