Vehicle Stability and Dynamics
Commercial vehicles operate on the same highways as passenger and other light vehicles but they are neither as maneuverable nor can they stop as quickly as light vehicles. This disparity often causes accidents so every effort is made by commercial vehicle manufacturers to continually improve both stability and braking. NTRCI focuses on both of these performance characteristics, with braking being covered in the Commercial Vehicle area of research. We perform the research that provides useful information about heavy trucks and their sub-systems that have an effect on the safety of the vehicle. Our research evaluates commercial vehicle technologies and generates new ideas by using modeling, analysis, and testing. The research team aims to improve the stability and dynamics to aid in crash prevention. NTRCI has used both modeling tools and on track testing to identify the underlying causes of both untripped and tripped rollovers. Our work has focused on single and longer combination vehicles using tractors with various trailers (van, tanker and flatbed). We explore the impact of changing components such as tires and stability systems with a goal to develop tools such as models and recommendations for truck manufacturers to use to improve stability.
Co-Simulation of Heavy Truck Tire Dynamics and Electronic Stability Control Systems
Increasingly new heavy trucks are being equipped with electronic driver aids such as electronic stability control systems ("ESC") to augment driver input and ensure vehicle stability in extreme maneuvers. While heavy truck vehicle and tire dynamic models are well understood and can be readily simulated today using computers, commercial ESC systems employ proprietary control algorithms developed by their suppliers. Therefore the effect of these systems on the overall vehicle dynamics cannot be readily simulated on the computer. Computer simulation is required to understand the effect of the system during accident avoidance maneuvers such as rapid lane changes which involve high lateral movement.
Electronic Stability Control Development for Commercial Vehicles
Modern electronic stability control (ESC) products automatically slow a vehicle rounding a corner too quickly or apply individual brakes when necessary to improve the steering characteristics of a vehicle. Air brake systems in North America provide no electronic communication between a tractor and semitrailer, limiting the degree to which control systems can be optimized.
Heavy Truck Tripped Rollover
Statistics kept by the National Highway Traffic Safety Administration (NHTSA) and other entities have shown that more than half of all heavy vehicle rollovers are associated with a run-off-road crash. Furthermore, the majority are "tripped;" that is, the truck rolled over because it ran over a drop-off or encountered a curb or other obstacle.
Heavy Vehicle Rollover Characterization
Heavy truck rollover crashes are not frequent occurrences. They represent approximately three percent of all crashes for combination trucks. Although this percentage is low, fatalities associated with heavy truck rollovers are inordinately high. Truck rollover is a factor in about 13 percent of all fatal crashes of combination trucks. In addition, it is not unusual for the economic losses of the payload and other associated insurance costs to be in the millions-of-dollars per crash.
Longer Combination Vehicles
As part of its ongoing effort to improve the safety, security, and operational efficiency of heavy commercial vehicles, NTRCI has begun to investigate the stability of Longer Combination Vehicles. LCVs, known colloquially as “doubles” or “triples” have more complicated dynamics than the more common tractor in combination with a single semitrailer. The goal of the phase conducted in 2011 is to measure and model the behavior of LCVs in simple maneuvers.
Tractor-Trailer Rollover Stability Enhancement
Heavy truck rollover crashes are not frequent occurrences. They represent approximately three percent of all crashes for combination trucks. Although this percentage is low, fatalities associated with heavy truck rollovers are inordinately high. Truck rollover is a factor in about 13 percent of all fatal crashes of combination trucks.