Control System Design for Electromechanical Brake System Using Novel Clamping Force Model and Estimator

• Published in: IEEE transactions on vehicular technology Vol. 70; no. 9; pp. 8653 - 8668
• Main Authors: Li, Yijun, Shim, Taehyun, Shin, Dong-Hwan, Lee, Seonghun, Jin, Sungho
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Angular position; Angular speed; Ball screws; Brake by wire systems; Brakes; Clamping; clamping force control; clamping force estimation; Clamps; Contact angle; Control systems design; Controllers; D C motors; disturbance observer; Disturbance observers; Electric contacts; Electric motors; Electromechanical brake; Feedback control; Feedforward control; Force; Force control; Friction; Functions (mathematics); Gear trains; Gears; Injection molding; Linear transformations; Mechanical transmissions; Phase error; Polynomials; Position measurement; Systems design; Torque; Tracking control
• ISSN: 0018-9545; 1939-9359
• DOI: 10.1109/TVT.2021.3095900

The electromechanical brake (EMB) is a key component of the brake-by-wire (BBW) system generating the clamping force between the brake pad and disk through an electric motor and mechanical transmission. Control of the clamping force has significant impact on the brake performance. In this paper, an EMB clamping force control system is developed that addresses several major challenges in the practical implementation. Firstly, a nonlinear EMB model including the DC motor, planetary gear set, ball screw, and clamping force model is built. In particular, a novel clamping force model is introduced based on a linear transform of two polynomial functions. For the control system design, a clamping force estimation algorithm is proposed that requires only the existing measurements of motor torque, angular speed, and position. The contact point of the brake pad and the disk is also estimated using an internal model controller and a Rauch-Tung-Striebel smoother. The tracking controller is based on the disturbance observer structure, with a PI feedback controller and a zero-phase error tracking feedforward controller. Furthermore, a unified architecture is proposed such that a smooth transition between gap closing and clamping force tracking is realized. Finally, the performance of the entire control system under various conditions is evaluated based on simulation.