Novel clamping force control for electric parking brake systems

In this paper we present a novel clamping force control method for electric parking brake systems without using force sensors. The control method consists of three steps for a simple control structure. First, we show how to approximately detect the initial contact point between brake pads and a brake disk with the angular velocity of motor. Second, the clamping force is estimated with the function of angular displacement from the maximum angular velocity. Third, since the motor continues to rotate about several tens milliseconds even after power-off we propose a novel on-off control method to decrease the inertia effect of DC motor. The proposed control method is validated by experiments. It enables low cost manufacturing of electric parking brake systems due to its simple control structure.