Tractor Semitrailer Stability Objective Performance Test Research - Yaw Stability.

摘要

This report documents the results from heavy-vehicle stability control (SC) system testing conducted by the National Highway Traffic Safety Administrations Vehicle Research and Test Center (VRTC) in 2008 and 2009. Tractor semitrailer SC research was conducted in three phases. Phase I (2006-2007) focused on understanding how heavy-vehicle stability control systems performed on the test track. Phase II (2007-2008) focused on the development of a dynamic test maneuver to challenge a tractor semitrailers roll propensity. This report documents Phase III research focused on the test track development of objective performance test maneuvers to challenge tractor semitrailers yaw stability. Phase III of research focused on developing performance tests that challenged the capabilities of a tractor-based stability control system designed to mitigate loss-of-control situations related to tractor semitrailer yaw stability. Evaluated were automated maneuvers called the Sine With Dwell (SWD), Half-Sine With Dwell (HSWD), Ramp With Dwell (RWD), Ramp Steer Maneuver (RSM), 150 ft. Brake-in-Curve (BIC), and Slowly Increasing Steer (SIS). These maneuvers are representative of lane-change, obstacle-avoidance, or negotiating-a-curve crash scenarios. Using these maneuvers, three tractors (four stability conditions), and four trailers were tested, with and without stability control enabled. Tractors and SC systems were evaluated in bobtail and loaded conditions (in combination with the trailers), on high-friction dry asphalt and reduced-friction Jennite test surfaces. To keep the test matrices manageable, all maneuvers and tractors were evaluated with a single trailer for loaded test conditions. Data from these series was then used to select a surface, loading condition, and a reduced set of maneuvers with which to evaluate stability of the tractors combined with other trailers. Using data from this test track research, several measures of performance (MOPs) were identified to have merit in evaluation of heavy-vehicle stability control systems. MOPs for both engine/power unit control and foundation braking were identified. Further, the SIS, RSM, and SWD test maneuvers were observed to be good performance maneuvers for evaluating tractor-trailer stability.