Monitoring vehicle positions

Details Monitoring vehicle positions Monitoring vehicle positions

1999-06-07

2001-09-04

Cuchlinski, Jr., William A. (Department: 3661)

Data processing: vehicles, navigation, and relative location

Navigation

Employing position determining equipment

C701S214000, C340S988000, C342S357490, C342S357490, C342S450000

Reexamination Certificate

active

06285953

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
A method and apparatus for monitoring the position of a vehicle or group of vehicles.
2. Related Art
Global positioning systems (GPS) are known in which a plurality of satellites in earth orbit are arranged to transmit signals such that a receiver located on the earth's surface is able, by triangulation techniques, to identify its location. Advances in such systems have resulted in them being included in small and relatively low cost equipment. As a result such technology is now in wide spread use in diverse equipment, for example for identification of the position of one or more vehicles.
British patent publication number 2 288 892 describes a system in which the position of a road vehicle is monitored by transmitting GPS positional data from a GPS system located on the vehicle to a base station. The data is transmitted using a radio link or GSM data link. Data is transmitted at closely spaced regular intervals so as to provide substantially real-time tracking of the vehicle.
With the system described in British patent publication number 2 288 892, the interval between successive transmission events must be relatively short in order to enable a remote monitoring station to obtain such real-time tracking data. Thus, a communication channel may be continuously kept open, tying up the channel, or opened and closed at short intervals, in which case the transmission time overhead of the protocol exchanges in creating the channel is significant in relation to the actual transmission time required for transmission of positional data. Such substantially constant use of a communications channel is expensive and can be inefficient e.g. in areas of poor reception.
French patent publication number 2 670 002 discloses the determination of vehicle position based on satellite signals from which vehicle position is calculated. A situation is described in which the satellite signals may be lost, possibly due to a vehicle entering a tunnel etc. Under these circumstances, subsequent vehicle positions are calculated by means of direction and distance measuring sensors. However, the document does not address the problem of facilitating the storage of a significant volume of positional data and is concerned primarily with providing current positional data to a driver.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, there is provided a method of monitoring a geographically moveable object, comprising the steps of substantially continuously receiving geographic position data at said geographically moveable object; and recording a first set of data representing the absolute geographic position of said object at a first position, characterised by creating relative position data from the difference between the absolute position data of a given position and the position data of a preceding recorded position; and recording a second set of position data representing said second position of said object relative to said first position.
In a preferred embodiment, subsequent sets of relative position data are recorded representing subsequent positions of said object relative to a preceding recorded position.
Preferably, the absolute position data comprises two n-bit words, where n may equal, for example, twenty-two and the relative position data comprises one n-bit word. Preferably, corresponding time and date data are associated with the position data.
According to a second aspect of the present invention, there is provided apparatus for monitoring a geographically moveable object, comprising means for substantially continuously receiving geographic position data at said geographically moveable object; and means for recording a first set of data representing the absolute geographic position of said object at said first position, characterised by means for creating relative position data from the difference between an absolute position data of a given position and the position data of a preceding recorded position; and means for recording a second set of position data representing a second position of said object relative to said first position.
In a preferred embodiment, the apparatus is arranged to record position data at intervals ranging from thirty seconds to thirty minutes and preferably the data is recorded at intervals ranging from two minutes to ten minutes.
In a preferred embodiment, the moveable object is a vehicle and the recording of data is initiated by the vehicle ignition being activated.
In a preferred embodiment, the apparatus includes means for transmitting recorded data to a base station to provide a history of the movement of the object at said base station. Preferably, position data is transmitted in response to a signal generated as a result of an operation of the moveable object, possibly in response to the ignition being deactivated.


REFERENCES:
patent: 5023798 (1991-06-01), Neukirchner et al.
patent: 5251078 (1993-10-01), Aki et al.
patent: 5289369 (1994-02-01), Hirshberg
patent: 0604404 A2 (1994-06-01), None
patent: 0 604 404 A (1994-06-01), None

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