Methods and systems for determining vertical location in enclosed spaces

1. A computer-implemented method for determining a vertical location of a hand-held computing device, the method comprising:

generating an estimate of expected vertical location based on items of beacon data received from beacons by a radio receiver of the hand-held computing device;

generating an error covariance of the estimate of expected vertical location based on the items of beacon data, wherein the generating the estimate of expected vertical location further comprises:

generating the estimate of expected vertical location based on a set of probabilities calculated at least in part from map data and beacon data comprising beacon distances, beacon distance accuracies, and items of beacon data time information;

calculating a level normalized change based on measurements of barometric pressure by a pressure sensor of the hand-held computing device;

calculating the vertical location of the hand-held computing device based on the level normalized change, the error covariance of the estimate of expected vertical location, and the estimate of expected vertical location; and

activating a relevant map for a level comprising the vertical location and displaying the vertical location on a display device of the hand-held computing device.

2. The computer-implemented method of claim 1 , wherein the calculating the vertical location of the hand-held computing device further comprises calculating based on a Kalman filter having inputs comprising the level normalized change, the error covariance of the estimate of expected vertical location, and the estimate of expected vertical location.

3. The computer-implemented method of claim 2 , wherein the inputs further comprise an error covariance of the level normalized change and the method further comprises refining the error covariances using items of measured data.

4. The computer-implemented method of claim 2 , further comprising iteratively calculating expected vertical location from beacon data and the level normalized change estimated from barometric pressure and error covariances.

5. The computer-implemented method of claim 2 , wherein the inputs further comprise an error covariance of the estimate of expected vertical location representing reliability of the items of beacon data.

6. The computer-implemented method of claim 1 , wherein the beacon data is read from a beacon data dictionary.

7. The computer-implemented method of claim 1 , wherein the generating the estimate of expected vertical location inside a structure based on the set of probabilities further comprises generating level weights sums from probabilities for beacons on each of a set of levels from which the items of beacon data been received.

8. The computer-implemented method of claim 1 , wherein the generating the estimate of expected vertical location inside a structure based on the set of probabilities further comprises generating probabilities for beacons on each of a set of levels based on the items of beacon data time information.

9. The computer-implemented method of claim 1 , wherein the method further comprises:

assigning time information to the items of beacon data;

estimating, based at least on the time information, beacon distances for the items of beacon data; and

estimating beacon distance accuracies for the items of beacon data.

10. The computer-implemented method of claim 9 , wherein the method further comprises:

receiving the items of beacon data at the radio receiver of the hand-held computing device;

determining validities of the items of beacon data; and

storing the beacon distances, beacon distance accuracies, and items of beacon data time information in a beacon data dictionary.

11. The computer-implemented method of claim 10 , wherein the beacon data dictionary comprises a table of datagrams having index keys based on a horizontal beacon location and a beacon level.

12. The computer-implemented method of claim 1 , further comprising iteratively updating the vertical location of the hand-held computing device using expectation estimates.

13. A hand-held computing device comprising:

a processor;

a memory coupled to the processor;

a display device electrically coupled to the processor;

a barometric pressure sensor electrically coupled to the processor;

a wireless communication system electrically coupled to the processor, the wireless communication system configured to receive items of beacon data wirelessly from beacons external to the hand-held computing device; and

wherein the memory stores a program that, when executed by the processor, causes the processor to:

generate an estimate of expected vertical location based on the items of beacon data, wherein when the processor generates the estimate of expected vertical location, the program further causes the processor to:

generate based on a set of probabilities calculated at least in part from map data and beacon data comprising beacon distances, beacon distance accuracies, and items of beacon data time information,

generate an error covariance of the estimate of expected vertical location based on the items of beacon data,

calculate a level normalized change based on measurements of barometric pressure by the barometric pressure sensor,

calculate a vertical location of the hand-held computing device based on the level normalized change, the error covariance of the estimate of expected vertical location, and the estimate of expected vertical location, and

display the vertical location on the display device.

14. The hand-held computing device of claim 13 , wherein when the processor calculates the vertical location of the hand-held computing device, the program further causes the processor to calculate based on a linear solution calculation having inputs comprising the level normalized change, the error covariance of the estimate of expected vertical location, and the estimate of expected vertical location.

15. A computer program product in a non-transitory computer-readable medium for location of a handheld computing device, the computer program product in a non-transitory computer-readable medium comprising instructions, which, when executed, cause a processor of a handheld computing device to perform:

generating an estimate of expected vertical location based on items of beacon data received from beacons by a radio receiver of the hand-held computing device, wherein the generating the estimate of expected vertical location further comprises:

generating based on a set of probabilities calculated at least in part from map data and beacon data comprising beacon distances, beacon distance accuracies, and items of beacon data time information;

generating an error covariance of the estimate of expected vertical location based on the items of beacon data;

calculating a level normalized change based on measurements of barometric pressure by a pressure sensor of the hand-held computing device;

calculating a vertical location of the hand-held computing device based on the level normalized change, the error covariance of the estimate of expected vertical location, and the estimate of expected vertical location; and

displaying the vertical location on a display device of the hand-held computing device.

16. The computer program product in a non-transitory computer-readable medium of claim 15 , wherein the generating the estimate of expected vertical location is based on map data.