Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
2000-11-01
2002-12-24
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S071000, C701S072000, C701S079000
Reexamination Certificate
active
06498976
ABSTRACT:
BACKGROUND
The present invention relates to a method and system for providing advice to an operator of a vehicle that the vehicle is being operated under conditions which may lead to vehicle rollover or, alternatively, to loss of control of the vehicle due to the manner in which the brakes of the vehicle have been applied. Desirably, the information is provided to the vehicle operator following the occurrence of vehicle operating conditions presenting an unacceptably increased risk so that the driver may be educated that these driving conditions have occurred and to avoid such conditions in the future.
Due to the differences in the center of gravity height and mass (load) of vehicles, the rollover threshold of commercial vehicles can vary significantly from load to load and vehicle to vehicle. Commercial vehicles typically include trucks as well tractors which are towing one or more semi-trailers. In the case of trucks, a load cargo area is carried by the truck itself. In the case of tractors with semi-trailers, a load cargo area is typically found in the trailers. In the case of truck tractors, a load cargo area is typically found both on the truck and in a towed trailer. Because trucks are constantly picking up and dropping off loads, the center of gravity of the vehicle and any trailers being towed thereby often varies from time to time. It is the vehicle operator's responsibility to be aware that these variations exist and to adjust the vehicle's speed appropriately, particularly when cornering or braking, so as to operate the vehicle safely. For purposes of explanation, the rollover threshold can be viewed. as operating conditions under which a vehicle would be expected to roll from a position which the vehicle wheels are traveling in contact with the ground toward a position where the vehicle is on its side or otherwise rolls over. In addition to vehicle load, a number of factors affect the rollover threshold, such as vehicle speed, braking conditions, the sharpness of any turn being undertaken, the slope of the road (e.g., crown and banking of curves), the stiffness of the vehicle and trailer suspension, as well as other factors.
The University of Michigan Transportation Research Institute has previously worked on a roll stability advisor system. This research work employed an instrumented fifth-wheel to estimate the trailer's center of gravity height and a lateral accelerometer to determine the lateral acceleration of the vehicle. Estimate of the center of gravity height and lateral accelerometer measurements were used as inputs to dynamically assess the percent of rollover threshold at which the vehicle was being operated. The rollover status information was displayed continuously to the driver. Instrumenting a fifth-wheel tractor-trailer coupling device on a commercial vehicle is not practical, due to reliability and durability problems, and is relatively expensive.
Road User Research of Australia has previously developed and field-tested a road stability advisor system for tractor-tanker-trailer vehicles. The Road User Research system employed Apriori rollover threshold knowledge about these vehicles, along with a lateral accelerometer located at the center of gravity of the tank-trailer, to dynamically assess the rollover threshold. The Apriori rollover threshold knowledge employed in the Road User Research system was not understood to be updated as the load on the vehicle changed. That is, the Road User Research system is understood to assume the rollover threshold is the same whether the vehicle was loaded or empty. Indicator lights on the dash of the vehicle were illuminated to provide the vehicle operator with information about the percent of rollover threshold approached during vehicle operation when predetermined rollover thresholds were exceeded.
Although these and other rollover detection systems have previously been known, a need nevertheless exists for an improved system for evaluating rollover risks and advising vehicle operators of such risks. In addition, an improved system for advising vehicle operators of braking conditions which can lead to loss of control of the vehicle is also desirable.
SUMMARY
The present invention is described throughout with reference to several embodiments. The invention is not limited to the specifically described embodiments. In addition, the invention encompasses features and method acts and steps which are novel and unobvious, both individually and in various combinations as set forth in the claims below.
In accordance with one aspect of an embodiment, the mass of the vehicle and any towed trailers is determined. For example, for a tractor-trailer combination in which two semi-trailers are being towed, the loaded vehicle and trailers may be weighed to determine the mass. As another alternative option, the load at the drive axles of the vehicle may be measured and supplemented by the measured load or by an assumption of the measured load to be carried by the other axles. Other mechanisms for actually measuring the mass of the vehicle may be used. Although relatively straightforward, measuring methods are not very practical or cost effective. This is particularly true in the case of tractor-trailer combination vehicles where any one of numerous trailers may be transported by the same tractor with the trailers having various configurations. Also, the mass is affected by numerous other factors such as how and the extent to which the vehicle and trailers have been loaded. Therefore, it is desirable to dynamically estimate the mass of the vehicle to account for these variables. In one specific approach, the vehicle mass may be estimated based on a summation of longitudinal forces acting on the vehicle and deriving the mass from an application of Newton's Second Law under such conditions. In particular, the mass of the vehicle and towed trailers, if any, may be repetitively estimated at least at selected times when the vehicle is being driven to provide a dynamically varying estimate of the mass.
As another aspect of this particular embodiment, a rollover acceleration value is determined. The rollover acceleration value may comprise a critical rollover threshold estimate related to the lateral acceleration of the vehicle at which the vehicle has an unacceptably increased risk of rolling over. More specifically, the critical rollover threshold may be a value which approaches or is equal to the threshold at which the vehicle and towed trailers, if any, would be expected to roll over under the conditions at which the vehicle is being operated. In a specific approach described below, the rollover acceleration value is determined based on the mass or estimate of the mass of the vehicle and load. The rollover acceleration value may be assigned based upon a rule set. This rule set may be embodied in a lookup table which lists rollover acceleration values for a particular type or types of vehicle having a mass which corresponds to the estimated mass. Consequently, when the mass is determined or estimated, the table can be checked to find a rollover acceleration value for that particular mass. As the mass varies, the table may again be checked to determine the applicable rollover acceleration value for the new estimate of mass of the vehicle. Alternatively, the rule set may be embodied in one or more formulas and may be specifically tailored to given vehicles with given types of loads. Desirably, the rollover values may be assigned based upon an assumed manner in which the cargo area being transported by the vehicle is loaded.
As a further aspect of an embodiment, the lateral acceleration of the vehicle under driving conditions may be measured or otherwise determined. For example, an acceleration sensor may be used which is mounted to the circuit board of an automatically modulated braking system (ABS system) which is used to control the braking of at least selected wheels of the vehicle. Although desirable, it is not required that a sensor be located at this location and other mechanisms for determining the lateral
Ehlbeck James M.
Kirn Christopher L.
Lenz Thomas
Moellenhoff Joerg
Roters Gerd
Cuchlinski Jr. William A.
Freightliner LLC
Klarquist & Sparkman, LLP
Marc-Coleman Marthe
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