Development of an active trailer differential braking system for car-trailer combinations

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The objective of the project is to develop a conceptual design of active trailer differential braking (ATDB) systems for car-trailer combinations. Despite the safety increases provided by electronic stability control (ESC) systems, nearly all these devices are designed for single-unit vehicles and take no account of external loads, such as trailers. Car-trailer combinations exhibit reduced stability at high speeds due to their complex configurations. Compared with single-unit vehicles, car-trailer combinations show unique unstable motion modes, including jack-knifing, trailer swing, and roll-over. These unstable motion modes are the common causes for accidents occurring on highways. To date, the majority of trailers use passive mechanisms to enhance their stability at high speeds. Unfortunately, the high-speed stability of a car-trailer system cannot be guaranteed with a passive mechanism, because operating conditions vary significantly, such as the variation of trailer payload, forward speed, road conditions, etc. To enhance the performance of car-trailer combinations, General Motors of Canada Limited (GM) is researching new active safety systems for the vehicle systems. With expertise from the UOIT team, the active safety system will be designed using an innovative ATDB technique, which is built upon existing technologies of ESC for single-unit vehicles. Collaborating with the GM engineers, the UOIT team will: 1) perform numerical simulations to examine the direction performance of a typical GM passenger car with and without an embedded ESC system when it tows a conventional trailer; and 2) conduct a conceptual design of an ATDB system and evaluate the effectiveness of the safety device by numerical simulations. The research project will address the following issues for the ATDB system design: 1) finding effective ways to determine the threshold limit to actuate the ATDB system; 2) determining effective control strategies to prevent jack-knifing unstable motion mode; and 3) identifying the effects of existing ESC system embedded on a car on the stability of the resulting car-trailer system when the car is towing. The innovative research will lay a solid foundation to fabricate physical ATDB prototypes in the next project.