Clamping Force Estimation for a Brake-by-Wire Actuator 1999-01-0482
In the scope of a research collaboration, Continental Teves (formerly ITT Automotive Europe) and Darmstadt University of Technology are developing control strategies for a low-cost Brake-by-Wire system, using no clamping-force or brake-torque sensor as feedback . However, since there is a wide range of variation in the efficiency of the gear units used in electromechanical brakes, this becomes a demanding task.
The paper first describes the assembly and operation of Continental Teves' third generation brake actuator, which is still operated using an integrated clamping force sensor . It introduces the development environment of Darmstadt University of Technology, consisting of a brake test stand, a complex brake actuator model, and a simplified brake actuator model. A detailed analysis of the motor rotor position and the motor current, both signals that are already available from the brake, discusses their advantages and disadvantages with regard to a possible use for clamping force estimation.
Based on the simplified brake model and the signal analysis, an algorithm to reconstruct the clamping force from the motor rotor position and the motor current only is introduced. To adjust the clearance without a force sensor, a strategy to detect the contact point between the brake pads and the brake disk is developed.
First experimental results of the clamping force estimation and the clearance management are shown.
Ralf Schwarz, Rolf Isermann, Jürgen Böhm, Joachim Nell, Peter Rieth
Darmstadt University of Technology, Continental Teves
International Congress & Exposition
Car Technology Yearbook 2000-CTY2000, Brake Technology and ABS/TCS Systems-SP-1413, Electronic Braking, Traction, and Stability Controls-PT-76, SAE 1999 Transactions - Journal of Passenger Cars-V108-6