US Patent 10549731 Electric parking brake for autonomous vehicles

A vehicle parking brake system includes a power bridge. The power bridge is electrically connected to a primary power source and to a secondary power source. The power bridge has a first condition in which the primary power source is active in which the primary source is electrically connected to a parking brake actuator. The power bridge has a second condition in which the primary power source is not active in which the secondary power source is electrically connected to the parking brake.