Systems and methods for rail worker and rail vehicle warning and position determination
System and methods are provided for warning a worker of a rail vehicle, or an operator of the rail vehicle of the worker. The system includes a worker device, a vehicle device, and a central server. The devices and server operate on one or a combination of actual or simulated satellite navigational signals, and beacon signals to determine the position of the devices, to generate a warning. The position determination may prioritize beacon signals over satellite navigation signals. The position determination may involve correcting a calculated position based on a measured power level of the beacon signal received from the beacon transmitter, an elapsed time since a previous beacon signal was last received by the device from the beacon transmitter, an elapsed time since a previous satellite navigation signal was received by the device, or an accuracy of the position of the device based on the satellite navigation signal.
1. A method for determining a position of a worker or a rail vehicle, the method comprising the steps of:
(a) providing a device adapted to be either carried by the worker or placed onboard the rail vehicle, the device comprising a receiver for receiving a beacon signal from each of a plurality of beacon transmitters; and
(b) receiving at the device a beacon signal from each of a plurality of beacon transmitters;
using at least one processor, performing the further steps of:
(c) for each one of the beacon transmitters:
(i) determining a power level of the beacon signal as received at the device from the one of the beacon transmitters;
(ii) calculating an estimated distance, D 1 , between the beacon transmitter and an initial value for a calculated position of the device based on the power level of the beacon signal received from the beacon transmitter;
(iii) calculating a distance, D 2 , between the beacon transmitter and the initial value for the calculated position of the device;
(iv) calculating a correction, Δ B , to the initial value of the calculated position of the device, based on a quantitative relationship in the form Δ B =K 3 ×(D 2 −D 1 ), wherein K B is a constant based on a quantitative relationship that negatively correlates K B to at least one or both of:
(A) the measured power level of the beacon signal received from the beacon transmitter; and
(B) an elapsed time since a previous beacon signal was last received by the device from the beacon transmitter;
(d) calculating a corrected calculated position of the device based on the initial value of the calculated position of the device and the corrections, Δ B ; and
(e) outputting the corrected calculated position of the device as the position of the device.
2. The method of claim 1 , wherein the constant, K 3 , is based on the quantitative relationship that negatively correlates K 3 to the measured power level of the beacon signal received from the beacon transmitter.
3. The method of claim 1 , wherein the constant, K 3 , is based on the quantitative relationship that negatively correlates K 3 to the elapsed time since the previous beacon signal was last received by the device from the beacon transmitter.
4. The method of claim 1 , wherein the method comprises the further steps of:
(a) receiving at the device a satellite navigation signal, and determining a position of the device based on the satellite navigation signal;
(b) using the at least one processor, calculating a distance, D SNS , between the position of the device based on the satellite navigation signal and the initial value for the calculated position of the device; and
(c) using the at least one processor, calculating a correction, Δ SNS , to the calculated position of the device, based on a quantitative relationship Δ SNS =K SNS ×D SNS , wherein K SNS is a constant based on a quantitative relationship that negatively correlates K SNS to at least one or both of:
(i) an elapsed time since a previous satellite navigation signal was received by the device; and
(ii) an accuracy of the position of the device based on the satellite navigation signal; and
wherein the step of calculating the corrected calculated position of the device is further based on the correction, Δ SNS .
5. The method of claim 4 , wherein the constant K SNS is based on the quantitative relationship that negatively correlates K SNS to the elapsed time since the previous satellite navigation signal was received by the device.
6. The method of claim 4 , wherein the constant K SNS is based on the quantitative relationship that negatively correlates K SNS to the accuracy of the position of the device based on the satellite navigation signal.
7. A system for determining a position of either a worker or a rail vehicle, the system comprising:
(a) a device adapted to be either carried by the worker or placed onboard the rail vehicle, the device comprising a receiver for receiving a beacon signal from each of a plurality of beacon transmitters; and
(b) at least one processor in communication with the receiver of the device, and operatively connected to a non-transient computer readable medium storing instructions executable by the processor to implement a method comprising the steps of:
(i) for each one of the beacon transmitters:
(A) determining a power level of the beacon signal as received at the device from the one of the beacon transmitters;
(B) calculating an estimated distance, D 1 , between the beacon transmitter and an initial value for a calculated position of the device based on the power level of the beacon signal received from the beacon transmitter;
(C) calculating a distance, D 2 , between the beacon transmitter and the initial value for the calculated position of the device;
(D) calculating a correction, Δ B , to the initial value of the calculated position of the device, based on a quantitative relationship in the form Δ B =K 3 ×(D 2 −D 1 ), wherein K B is a constant based on a quantitative relationship that negatively correlates K B to at least one or both of:
(1) the measured power level of the beacon signal received from the beacon transmitter; and
(2) an elapsed time since a previous beacon signal was last received by the device from the beacon transmitter;
(ii) calculating a corrected calculated position of the device based on the initial value of the calculated position of the device and the corrections, Δ B ; and
(iii) outputting the corrected calculated position of the device as the position of the worker or the rail vehicle.
8. The system of claim 7 , wherein the constant, K 3 , is based on the quantitative relationship that negatively correlates K 3 to the measured power level of the beacon signal received from the beacon transmitter.
9. The system of claim 7 , wherein the constant, K 3 , is based on the quantitative relationship that negatively correlates K 3 to the elapsed time since the previous beacon signal was last received by the device from the beacon transmitter.
10. The system of claim 7 , wherein:
(a) the device comprises a satellite navigation signal receiver module for determining a position of the device based on the satellite navigation signal;
(b) the method comprises the further steps of:
(i) calculating a distance, D SNS , between the position of the device based on the satellite navigation signal and the initial value for the calculated position of the device; and
(ii) calculating a correction, Δ SNS , to the calculated position of the device, based on a quantitative relationship Δ SNS =K SNS ×D SNS , wherein K SNS is a constant based on a quantitative relationship that negatively correlates K SNS to at least one or both of:
(A) an elapsed time since a previous satellite navigation signal was received by the device; and
(B) an accuracy of the position of the device based on the satellite navigation signal; and
(c) the step of calculating the corrected calculated position of the device is further based on the correction, Δ SNS .
11. The system of claim 7 , wherein the constant K SNS is based on the quantitative relationship that negatively correlates K SNS to the elapsed time since the previous satellite navigation signal was received by the device.
12. The system of claim 7 , wherein the constant K SNS is based on the quantitative relationship that negatively correlates K SNS to the accuracy of the position of the device based on the satellite navigation signal.
13. A computer program product for determining a position of either a worker or a rail vehicle, for use with a device adapted to be either carried by the worker or placed onboard the rail vehicle, the device comprising a receiver for receiving a beacon signal from each of a plurality of beacon transmitters, the computer program product comprising a non-transient computer readable medium storing instructions executable by at least one processor to implement a method comprising the steps of:
(a) for each one of the beacon transmitters:
(i) determining a power level of the beacon signal as received at the device from the one of the beacon transmitters;
(ii) calculating an estimated distance, D 1 , between the beacon transmitter and an initial value for a calculated position of the device based on the power level of the beacon signal received from the beacon transmitter;
(iii) calculating a distance, D 2 , between the beacon transmitter and the initial value for the calculated position of the device;
(iv) calculating a correction, Δ B , to the initial value of the calculated position of the device, based on a quantitative relationship in the form Δ B =K 3 ×(D 2 −D 1 ), wherein K B is a constant based on a quantitative relationship that negatively correlates K B to at least one or both of:
(A) the measured power level of the beacon signal received from the beacon transmitter; and
(B) an elapsed time since a previous beacon signal was last received by the device from the beacon transmitter;
(b) calculating a corrected calculated position of the device based on the initial value of the calculated position of the device and the corrections, Δ B ; and
(c) outputting the corrected calculated position of the device as the position of the worker or the rail vehicle.
14. The computer program product of claim 13 , wherein the constant, K 3 , is based on the quantitative relationship that negatively correlates K 3 to the measured power level of the beacon signal received from the beacon transmitter.
15. The computer program product of claim 13 , wherein the constant, K 3 , is based on the quantitative relationship that negatively correlates K 3 to the elapsed time since the previous beacon signal was last received by the device from the beacon transmitter.
16. The computer program product of claim 13 , wherein the device comprises a satellite navigation signal receiver module for determining a position of the device based on the satellite navigation signal, and wherein:
(a) the method comprises the further steps of:
(i) calculating a distance, D SNS , between the position of the device based on the satellite navigation signal and the initial value for the calculated position of the device; and
(ii) calculating a correction, Δ SNS , to the calculated position of the device, based on a quantitative relationship Δ SNS =K SNS ×D SNS , wherein K SNS is a constant based on a quantitative relationship that negatively correlates K SNS to at least one or both of:
(A) an elapsed time since a previous satellite navigation signal was received by the device; and
(B) an accuracy of the position of the device based on the satellite navigation signal; and
(b) the step of calculating the corrected calculated position of the device is further based on the correction, Δ SNS .
17. The computer program product of claim 13 , wherein the constant K SNS is based on the quantitative relationship that negatively correlates K SNS to the elapsed time since the previous satellite navigation signal was received by the device.
18. The computer program product of claim 13 , wherein the constant K SNS is based on the quantitative relationship that negatively correlates K SNS to the accuracy of the position of the device based on the satellite navigation signal.