Investigation of driver comfort and safety perception at different fallback levels of conventional and by-wire automotive brake systems

Brake-by-wire refers to the adjustment and replacement of traditional brake components such as pumps, hoses, fluids, brake boosters, and master cylinders by electronic sensors and actuators. The innovative designs of these brake concepts pose new challenges for the automotive industry with regards to brake system availability and the fallback level impact for the driver.

This thesis investigates driver’s perceptions of the comfort and safety of both conventional and by-wire automotive brake systems at different fallback levels.

Brake pedal simulation techniques and real vehicle field trials were used to evaluate brake performance, brake failure warning, brake pedal perception and the usability of such systems for every day drivers.

A static brake pedal simulation test was performed using a real vehicle environment. The test participants were evaluated on their perception and performance on the following brake modes: normal brake function, brake booster and brake circuit failure.

A proving ground study was undertaken using two test vehicles, both of which featured a trigger option that would activate a secondary brake system and its corresponding fallback level. The third tested fallback level scenario was presented with an extended brake failure warning based on current state-of-the-art design guidelines and legal requirements. The concept and setup of the dynamic proband test can also be adapted for user acceptance tests of new complex electronic brake system designs.