Numerical evaluation of braking feel to design optimal brake-by-wire system

Over the years there have been significant advances in automotive engineering thanks to recent development of electronics. Antilock brake system (ABS) technology with modern electronic components has shown superior braking performance to conventional vehicles on highways. The brake-by-wire (BBW) system equipped with powerful electronic devices also allows us to arbitrarily tailor the force feel at brake pedal. Conventionally, however, the brake system has been developed through trial and error on test tracks, which necessitates a great amount of time and cost. This study attempts to establish an analytical tool to evaluate braking feel to help design optimal brake systems. First, mathematical models of brake systems are developed and are confirmed through computer simulations. Second, mechanical impedance at brake pedal is modelled based on the developed brake system models. The brake pedal feel is represented in the form of impedance surface. Third, to provide a guideline to design optimal braking feel, relations between pedal force, pedal stroke and vehicle deceleration are investigated. An expert test driver's evaluation process is modelled based on his subjective ratings of brake systems.