Location and tracking of people with combined use of RF infrastructure and dead reckoning modules
View Patent ↗A system for tracking persons and other assets in a structure, having a multi-function tracking tag and a network of fixed RF receivers forming a gateway array. The location of the person being tracked is calculated by a computer using an algorithm that weights each separate signal according to the probability of its accuracy, thus using data with the least error. A preferred algorithm is shown in FIG. 2.
1. A system for tracking persons and other assets in a structure, comprising:
a multi-function tracking tag comprising an RF beacon for transmitting an RF beacon signal and a dead reckoning module, said RF beacon signal including data from said dead reckoning module;
a plurality of RF transceivers of known location forming a wireless array for receiving said RF beacon signal from said multi-function tracking tag and thereafter re-transmitting said RF beacon signal; and
a computer associated with said plurality of RF transceivers, said computer being programmed to determine a location of said multi-function tracking tag using an algorithm wherein said algorithm utilizes signal strength of said RF beacon signal and said data from said dead reckoning module to calculate said location of said multi-function tracking tag wherein said algorithm minimizes a squared error between a position estimate based on said signal strength of said RF beacon signal and a position estimate based on said data from said dead reckoning module.
2. The system of claim 1 , which includes a plurality of multi-function tracking tags.
3. The system of claim 1 , wherein said position estimate based on said signal strength is given less weight in said algorithm as said signal strength decreases.
4. The system of claim 1 , wherein said dead reckoning module comprises an altimeter, a magnetometer and an accelerometer.
5. The system of claim 4 , wherein said dead reckoning module combines readings from said altimeter, said magnetometer and said accelerometer with an initial starting position to produce a new estimated position.
6. The system of claim 3 , wherein said position estimate based on said data from said dead reckoning module is given less weight in said algorithm as time increases.
7. The system of claim 1 , wherein said data from said dead reckoning module comprises a dead reckoning position estimate of said multi-function tracking tag.
8. The system of claim 1 , wherein said computer displays said location of said multi-function tracking tag on a user display.
9. A method comprising the steps of:
transmitting an RF beacon signal from a multi-function tracking tag comprising an RF beacon and a dead reckoning module, said RF beacon signal including estimated position data from said dead reckoning module;
receiving said RF beacon signal at a plurality of RF transceivers of known location within a structure forming a wireless array; and
determining a location of said multi-function tracking tag using an algorithm programmed on a computer associated with said plurality of RF transceivers, wherein said algorithm utilizes signal strength of said RF beacon signal and said estimated position data from said dead reckoning module to calculate said location of said multi-function tracking tag wherein said algorithm minimizes a squared error between a position estimate based on said signal strength of said RF beacon and a position estimate based on said estimated position data from said dead reckoning module.
10. The method of claim 9 further comprising:
displaying said location of said multi-function tracking tag on a user display of said computer.
11. The method of claim 9 further comprising:
weighing said position estimate based on said signal strength less over distance from said RF transceivers in said algorithm.
12. The method of claim 11 further comprising:
weighing said position estimate based on said position data from said dead reckoning module less over time.
13. The method of claim 12 wherein said position data from said dead reckoning module comprises a dead reckoning position estimate of said multi-function tracking tag.
14. A system comprising:
a multi-function tracking tag comprising an RF beacon for transmitting an RF beacon signal and a dead reckoning module, wherein said RF beacon signal includes estimated position data from said dead reckoning module;
a plurality of RF transceivers forming a wireless array within a structure to receive said RF beacon signal; and
a computer associated with said plurality of RF transceivers, said computer being programmed to determine a location of said multi-function tracking tag using an algorithm wherein said algorithm utilizes signal strength of said RF beacon signal and said estimated position data from said dead reckoning module to calculate said location of said multi-function tracking tag by minimizing a squared error between a position estimate based on said signal strength of said RF beacon and a position estimate based on said position data from said dead reckoning module to thereby implement a system for tracking persons and other assets in a structure.
15. The system of claim 14 , wherein said position estimate based on said signal strength is given less weight in said algorithm as said signal strength decreases.
16. The system of claim 14 , wherein said position estimate based on said position data from said dead reckoning module is given less weight in said algorithm as time increases.
17. The system of claim 14 further comprising:
a user display on said computer to display said location of said multi-function tracking tag.
18. The system of claim 14 further comprising:
a plurality of additional RF transceivers disposed outside of said structure.