A New Self-Contained Electro-Hydraulic Brake System

Abstract

The automotive brake system plays a significant role not only in the deceleration and stopping process, but also in many stability control strategies. To overcome the limitations of conventional brake systems and to improve vehicle control strategies such as traction control, and differential braking, a new generation of brake systems called the brake-by-wire system has been introduced to the vehicle industry. This generation of brake systems combines electrical, mechanical and, in some cases, hydraulic components. Although different types of brake-by-wire mechanisms have been developed in the past two decades, there still exist demands for further improvement and developing new brake mechanisms in the automotive industry due to the ever increasing demand for better safety and performance. This research proposes a novel brake-by-wire system based on cam actuation. This system is a combination of electrical, mechanical and hydraulic components. The unique feature of the cam actuation brake system proposed in this research is that the characteristics of the motor torque amplification can be optimized by careful design of the cam shape. The compactness and self-contained characteristic of the design allow the brake system to be installed on each wheel enabling fully independent control of each wheel for better stability control. Moreover, the cam actuated brake has a fail-safe advantage by keeping the direct connection between the driver and the brake calipers in case of any system failure. In this work, different subsystems of the brake system and their components are explained, the dynamic model of the system is found and the design parameters are optimized. Specifically, the optimal design problem has been formulated by taking the geometry of the cam as the optimization variable and the open-loop response time of the brake system as the objective function to be minimized. The solution to this problem is then obtained by the multi-layer design optimization process using the genetic algorithm (GA). Various control algorithms are applied to the developed cam actuated brake system to investigate their performance in terms of tracking a desired braking pressure.