Automatic determination of traffic signal preemption using differential GPS
First Claim
1. A traffic signal preemption system using differential global positioning system (GPS) corrections, for a signalized intersection having a traffic signal controller capable of operation in a normal mode and in a preemption mode upon receiving a signal for preemption, the system comprising:
- a traffic signal subsystem, including;
a GPS reference receiver having an antenna installed at a known position, for receiving GPS signals and computing measurement corrections for the GPS signals;
a communication radio for receiving data from an approaching emergency vehicle, andan intersection computer, containing a model of the intersection and programmed such that corrected vehicle position, speed and direction measurements are used to determine when to send a signal to the traffic controller to switch to preemption mode in such a way as to minimize disruption of normal traffic;
a vehicle subsystem, including;
a GPS receiver for receiving GPS signals, said signals including signals from which the vehicle'"'"'s position, speed and direction can be determined;
a communication radio for transmitting data to the traffic signal subsystem radio, anda vehicle computer, for coordinating operation of the vehicle GPS receiver and the vehicle communication radio; and
a differential GPS subsystem portion in communication with the GPS reference receive to receive therefrom the measurement corrections and in communication with the GPS receiver to receive the GPS signals and to compute and to provide to the interaction computer, corrected vehicle position, speed and direction.
9 Assignments
0 Petitions
Accused Products
Abstract
A traffic signal preemption system, and a related method for its use, using differential global positioning system (GPS) measurements for accurate monitoring of the position, speed and direction of an emergency or service vehicle approaching a controlled intersection. The preemption system includes a reference GPS receiver, for computing GPS measurement corrections, and a GPS receiver in each vehicle, which transmits its GPS measurements by radio to a receiver located at the controlled intersection. A computer also located at the intersection uses corrected vehicle position, speed and direction measurements, in conjunction with previously recorded data defining approach routes to the intersection, to determine the optimum time to switch a traffic light controller to preemption mode to permit safe passage of the vehicle. GPS measurement corrections may be applied in a vehicle computer or in the computer located at the intersection. Other modes of operation of the system include a self-survey mode, whereby the reference GPS receiver determines its own true position by averaging position measurements over a period of a day or two, and a learn mode, whereby the intersection computer "learns" unusual approach routes to the intersection as the vehicle traverses the approach routes and transmits position and velocity measurements.
195 Citations
18 Claims
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1. A traffic signal preemption system using differential global positioning system (GPS) corrections, for a signalized intersection having a traffic signal controller capable of operation in a normal mode and in a preemption mode upon receiving a signal for preemption, the system comprising:
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a traffic signal subsystem, including; a GPS reference receiver having an antenna installed at a known position, for receiving GPS signals and computing measurement corrections for the GPS signals; a communication radio for receiving data from an approaching emergency vehicle, and an intersection computer, containing a model of the intersection and programmed such that corrected vehicle position, speed and direction measurements are used to determine when to send a signal to the traffic controller to switch to preemption mode in such a way as to minimize disruption of normal traffic; a vehicle subsystem, including; a GPS receiver for receiving GPS signals, said signals including signals from which the vehicle'"'"'s position, speed and direction can be determined; a communication radio for transmitting data to the traffic signal subsystem radio, and a vehicle computer, for coordinating operation of the vehicle GPS receiver and the vehicle communication radio; and a differential GPS subsystem portion in communication with the GPS reference receive to receive therefrom the measurement corrections and in communication with the GPS receiver to receive the GPS signals and to compute and to provide to the interaction computer, corrected vehicle position, speed and direction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of operating a traffic signal preemption system for a signalized intersection having a traffic contoller, comprising the steps of;
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receiving global positioning system (GPS) signals at a reference GPS receiver whose location is accurately known; computing differential GPS corrections to be applied to received GPS signals; receiving GPS signals at a vehicle GPS receiver said signals including signals from which the vehicle'"'"'s position, speed and direction can be determined; transmitting some form of the received vehicle GPS signals to a traffic signal intersection subsystem; using the differential GPS corrections, computing corrected vehicle position, speed and direction; and computing from the corrected vehicle position, speed and direction measurements, taken with known intersection approach data, an optimum time to send a signal to the traffic controller to switch to a preemption mode of traffic control. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification