Modeling of air brakes for onboard diagnostics of heavy trucks

Abstract

Accidents involving commercial vehicles have disastrous consequences; most of the times they result in human fatalities, environmental damage, traffic congestion leading to fuel wastage and associated productivity losses. Moreover, with the rapid increase in the commercial vehicles traffic over the past few years, improved preventive and active measures are necessary to minimize commercial vehicle accidents and to enhance the safety of our roadways. The brake system is one of the critical components in ensuring the safety of the vehicle on the road. In a recent National Traffic Safety Board's ( NTSB ) heavy truck inspection survey, it was found that the defects in brakes/brake adjustment account for an average 56 percent of the trucks being declared out of service. Worn brake pads and tires, air leaks at hoses, connections, valves and brake chambers of the airbrake system along with the significant time delay in the actuation of tractor and trailer brakes degrade the vehicle braking and handling performance thereby increasing the potential for fatal accidents. As a result, there is a need for the advanced diagnostic system that monitors the health of air brakes and thus aiding in preventing the accidents. Therefore, the research is to develop a diagnostic algorithm that enhance the preventive safety of the vehicle. This could be accomplished by developing a mathematical model for the air brake system of a commercial vehicle and then utilizing the fault detection algorithms using analytical redundancy in a dynamic system. This could be done by predicting the redundant measurements using some of the reliable sensors and comparing with that of the values from the model. Using the mismatch between these, error residuals can be generated that carry the signature of the health of the airbrake system. The algorithm could also be experimentally implemented and verify their efficacy on an air brake system in the laboratory. The focus of the work that is presented here is to develop a mathematical model of the air brake systems that suits the development of the diagnostic algorithm and also to set up a test bench for the experiments.