Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Traffic analysis or control of surface vehicle
Reexamination Certificate
1999-04-09
2001-01-23
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Traffic analysis or control of surface vehicle
C701S118000, C701S207000, C701S220000, C340S905000, C340S989000
Reexamination Certificate
active
06178374
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for the wireless transmission of data to a traffic center for the purpose of assessing traffic in segments of a road network. The data are collected in a plurality of vehicles (floating cars) that travel in traffic and are equipped with sensor systems for data collection. The invention also relates to a device to implement this process.
2. Description of the Prior Art
Various methods are known for the metrological collection of data for traffic assessment in segments of a road network. Often, stationary or fixed sensors installed at roadside such, for example as induction loops, are used at especially critical locations to measure technical traffic variables, such as the number of vehicles passing during a given time period or the average speed of these vehicles. However, installing stationary sensors such as those disclosed in U.S. Pat. No. 5,317,311 at roadside or in the road surface is expensive, as is the maintenance of such sensors. As a rule, such sensors transmit current measurement data to a traffic center for further assessment at regular intervals.
Recently, there has been discussion and testing of processes in which data measurement for traffic assessment is conducted in the vehicles taking part in traffic. The vehicles used for this purpose are equipped with sensors. Such sensor vehicles are also called “floating cars.” This concept of data collection presupposes wireless communications for data transfer between the floating cars and a traffic center. Preferably, data transfer is carried out via radio. Due to the limited capacity of the broadcast channels, such communications must, for technical as well as economic reasons, be limited, to the greatest possible extent, to the necessary minimum. Instead of constantly maintaining radio contact, a typical application of the floating car concept disclosed, for example in DE 195 13 640 simply transmits the most recent measurement data at regular intervals. These data include, in particular, the time of day, the location and speed of the vehicle and, as applicable, other measurement variables on the vehicle surroundings, e.g., fog, rain or black ice. Such a chronological chain of individual data is described hereinafter as the “driving profile.”
However, this known process is not completely satisfactory. It has the disadvantage that, despite data reduction, measurement data with little informative value are frequently transmitted. The reporting behavior of each vehicle is controlled purely chronologically, for example, and is not directly influenced by the usefulness of the transmitted data for the purpose of traffic assessment. The individual floating cars report their data regardless of whether they happen to be located on a completely empty road or in heavy traffic or in a zone where traffic has been disrupted by a recent accident. Since the primary goal of data collection for traffic assessment is to detect traffic disruptions, reports of non-disrupted traffic contribute only slightly to this goal.
SUMMARY OF THE INVENTION
The object of the invention is to further develop a generic process in such a way that data transmission from floating vehicles to a traffic center is limited to the greatest possible extent largely to data with great informative value for traffic assessment. Another object of the invention is to provide a device to implement this process.
This object is attained according to the invention by a process for wireless transmission of data for traffic system assessment in segments of a road network to a traffic center, comprising the steps of collecting data using sensors in a floating vehicle in the road network, forming a current driving profile from the data, deriving actual values of characteristic driving profile properties from the current driving profile, forming expected values of characteristic driving profile properties based on preestablished traffic situation information, comparing the actual values to the expected values, assessing a difference found in said step of comparing and determining whether the difference is a serious deviation from the expected values based on preestablished decision criteria, and transmitting the actual values to the traffic center if it is determined that the difference is a serious deviation in said step of determining.
The object is also attained by a device for wireless transmission of data for traffic system assessment in segments of a road network to a traffic center, including a sensor system mounted in a floating vehicle for determining driving profile data, a processing device for receiving the driving profile data from said sensor system and determining actual values and expected values of characteristic driving profile properties, a comparator for comparing the actual values and expected values of the characteristic driving profile properties and determining a difference between said actual values and said expected values, a first memory comprising decision criteria, and a transmitting device for transmitting said driving profile data to the traffic center when said difference between said actual values and said expected values is determined to be a serious deviation from said expected values based on said decision criteria in said first memory.
By means of the process according to the invention, the transmission of redundant or irrelevant data is kept to a minimum. The starting point of the invention is the idea that data reflective of the picture of the traffic situation that already exists (or probably exists) at a traffic center are not of interest in themselves and therefore, if possible, should not be transmitted by individual data collection vehicles. This situation must be objectively recognizable in the individual vehicles, so that an appropriate decision to transmit data or to refrain from transmitting data from each vehicle can be made.
The basis of the invention is the sensor data collected in a vehicle. These sensor data are collected cyclically, for example, then stored temporarily and assessed in the vehicle. The totality of sensor data creates a “driving profile.” In general terms, a driving profile is a description of driving behavior over a certain route segment or a certain time period. Simple forms of driving profiles include: speed travelled as a function of time (speed-time graph), location as a function of time (location-time graph), and speed as a function of location. Of course, other sensor data, such as turning angle, acceleration, etc. can also be used for the driving profile. A driving profile has in fact been “driven” and describes the actual behavior of the vehicle.
According to the invention, a current driving profile is created from the sensor data collected in the vehicle. Then, in the vehicle, characteristic properties in the form of actual values are derived from that current driving profile. Further, based on predetermined traffic situation information, characteristic driving profile properties in the form of expected values are also arrived at in the vehicle. In the framework of the invention, these expected values of the driving profile properties are then compared with the actual values of the driving profile properties. After this, the differences found by means of this comparison are evaluated in the vehicle on the basis of preestablished decision criteria. Based on this evaluation, collected data are transmitted to the traffic center only if required according to the decision criteria.
In the sense of the present invention, the driving profile properties serve to summarize a driving profile in the form of a few criteria or characteristic values, so that this profile can then be checked, as simply as possible, for compatibility with a fictitious driving profile that corresponds to the traffic situation existing according to traffic information that has been received. In the simplest case, for example, the average speed at a preestablished time or segment interval could be used as the characteristic property. The values of
Mohlenkamp Klaus
M{umlaut over (u)}ller Thomas
Schulz Werner
Vieweg Stefan
Cohen & Pontani, Lieberman & Pavane
Cuchlinski Jr. William A.
Donnelly Arthur D.
Mannesmann AG
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