Headway Control Systems And The Heavy Commercial Vehicle-A Case Study

The addition of control systems to highway vehicles has received considerable attention in recent years. Much of this work pertains to the development of control systems for passenger cars. However, since the power-to-weight ratios of heavy trucks make them quite different from passenger cars with regard to maintaining speed and headway, tieaVy·tnickS merit special attention. This paper focuses on a headway-control system that was designed and installed in a commercial heavy duty tractor-semitrailer combination. The project involved design, simulation, testing, and performance evaluation of the system. The headway control system described in this paper, utilizes a range and range-rate sensor to determine whether the road is clear. If the road is clear, the system acts as a conventional cruise control. If a slower moving vehicle is detected, the system switches to a headway control mode, whereupon it utilizes information from the sensor to maintain a prescribed headway. Principles of design are presented, experimental results are presented and analyzed, and a methodology for testing such headway-control systems is suggested. These experimental results are used to highlight and evaluate the engineering measures needed to characterize system performance under various conditions of road geometry, traffic, and maneuvering scenarios. Operational aspects of the use of headway control systems in the environment of heavy-duty trucking are discussed. This paper will be useful to any parties concerned with developing, evaluating or specifying headway control or other systems in the longitudinal collision avoidance class of functionality.