Clamping-Force Control for Electromechanical Brake

The estimation of the frictional and clamping forces is one of the key issues in the design and implementation of the electromechanical brake (EMB) system. In this paper, a clamping-force control algorithm is presented along with a consideration of the frictional characteristics and the estimation of the clamping force for a planetary reduction gear-type EMB. The frictional model is developed by including the frictional effect of the motor, the planetary gear, and the screw thread. Since the clamping-force estimation requires the distance of the contact gap between the pad and the disk, an initial gap-distance control algorithm that uses the gradient change of the motor torque is proposed. This paper is concluded with a discussion of the performance of the control algorithm by comparing the simulation results with the experimental results.