Fault Tolerance Analysis of Alternate Automotive Brake System Designs

Brake systems in current production automobiles are the result of a long evolutionary process beginning with the first practical hydraulic brake patent in 1917. While the basic hydraulic design has many advantages, recent modifications to this system for anti-lock braking and traction control considerably increase the cost of manufacture. As a result, many manufacturers are investigating the possibility of developing alternate braking system structures that cost less and can easily interface with vehicle electronics. Evaluating these systems for fault tolerance and failure effects is crucial to provide a safe and reliable vehicle braking system. This paper demonstrates the use of the Fault Tree Analysis method for carrying out such an evaluation.

An example system is presented to illustrate the application of this method to automobile brake design. Through this example, the paper demonstrates how one can evaluate the effects of a failure propagation through the system, suggest structural changes to the system to improve its fault tolerance, and analyze systems where detailed internal functions of some the subsystems are unknown. The results of the analysis method for the example system are also presented.