Safety and Comfort for All: An affordable Hill-Hold and Automated Parking Brake System

With an ever-increasing number of vehicles on Indian roads, the safety and ease of driving has become a very important criterion for the customers. In passenger and commercial vehicles, while launching a vehicle on gradient or stop and go traffic in hilly region, the vehicle tends to roll back/forward in the opposite direction of the intended movement. This undesirable movement is also a safety issue, as this may cause collision with the vehicle on the rear or in front. It requires a skilled driver to coordinate between the clutch pedal, brake (also handbrake in some situations) and accelerator pedal to prevent the vehicle from rolling back while handling such situations. It also leads to clutch disc wear and heating as the driver may tend to slip the clutch to prevent the vehicle from rolling back. Hill hold is a driver assist feature which prevents the vehicle roll back/roll forward during launch operation on uphill/downhill conditions. Hill-hold is offered as an add-on feature on most vehicles equipped with Electronic Stability Program (ESP). Hill hold is achieved in ESP by applying the rear or all four brakes of the vehicle. ESP is not commonly provided in entry level vehicles due to its higher cost because of a lot of additional components and controls. Another shortcoming of the Hill-hold through ESP is that, due to its control strategy it holds the brakes only for approximately 3-5 seconds, after which the vehicle will start rolling back. At Schaeffler India, two hill hold concepts have been developed for entry level vehicles and above. These systems achieve the Hill-hold and Auto Park brake function either by purely mechanical or mechatronic means. The mechanical system consists of a transmission integrated Hill-hold system. The mechatronic system is designed for easy integration in the existing parking brake (hand brake) system with minimal modifications. The paper describes the various development phases from collecting the voice of customer, input requirements, system arrangements and architecture, design and development steps till validation and results.