Method and system for determining the height of a device above ground
A device updates a value representing its current height above ground when it detects a height change. The device uses the slope calculated from collected barometric pressure data samples to calculate height change during a period when the value of the slope exceeds a predetermined value. The device also analyzes a predetermined number of barometric pressure sensor data samples preceding and succeeding a height change indicated by the slope change. The device performs an evaluation, i.e., determining the difference between an average of the preceding and succeeding samples, to determine a height change. The device may select either the slope-of-the-curve-during-the-height-change-period method or the difference-between-the-averages method based on meeting a criterion. The processor de-energizes a GPS circuit, height determination method, and sets the height above ground to zero if it detects movement. Placing the device on a charger resets the device's height value to the charger height above ground.
1. A method comprising:
receiving, by a device, barometric pressure data samples from a barometric pressure sensor;
storing, by the device, the barometric pressure data samples in a buffer;
evaluating, by the device, the barometric pressure data samples to determine a best fit line that represents a change in height of the device;
determining, by the device, that the barometric pressure data samples in the buffer represent data substantially following a transition to a zero slope;
determining, by the device and based on determining that the barometric pressure data samples in the buffer represent data substantially following the transition to the zero slope, a slope over a slope period commencing with one of one or more barometric data sample times that substantially correspond to transitioning from the zero slope to a non-zero slope and ending with a sample time substantially corresponding to the transition to the zero slope;
applying, by the device, power to a global positioning system (GPS) component based on the determined slope;
receiving, by the device, a GPS signal based on applying the power to the GPS component;
determining, by the device, movement information corresponding to the device based on the GPS signal;
determining, by the device, whether a threshold is satisfied based on the movement information corresponding to the device; and
selectively:
setting, by the device and when the threshold is satisfied, a wait time that delays reading more barometric pressure data samples from the barometric pressure sensor and delays a next time at which more power is applied to the GPS component; or
determining, by the device and when the threshold is not satisfied, a change-in-height offset value based on the determined slope over the slope period and based on the slope period; and
applying, by the device and when the threshold is not satisfied, the change-in-height offset value or a differential change-in-height value to a previously determined current height value of the device based on the change-in-height offset value.
2. The method of claim 1 , further comprising:
setting to zero the previously determined current height value when the threshold is satisfied.
3. The method of claim 1 , further comprising:
entering a wait state for the wait time when the threshold is satisfied.
4. The method of claim 1 , wherein the GPS component includes GPS circuitry.
5. The method of claim 1 , wherein the movement information corresponds to a speed of the device.
6. The method of claim 1 , wherein the determined slope is compared to a first criterion for movement in an ascending direction and a second criterion for movement in a descending direction.
7. A system comprising:
a device to:
receive data corresponding to barometric pressure data samples from a barometric pressure sensor;
store the barometric pressure data samples in a first memory;
evaluate the data corresponding to the barometric pressure data samples to determine a best fit line that represents a change in height of the device;
determine that the barometric pressure data samples in the first memory represent data substantially following a transition to a zero slope;
determine, based on determining that the barometric pressure data samples in the first memory represent data substantially following the transition to the zero slope, a slope over a slope period;
apply power to a global positioning system (GPS) component based on the determined slope;
receive a GPS signal based on applying the power to the GPS component;
determine movement information corresponding to the device based on the GPS signal;
determine whether a threshold is satisfied based on the movement information corresponding to the device; and
selectively:
set, when the threshold is satisfied, a wait time that delays reading more barometric pressure data samples from the barometric pressure sensor and delays a next time at which more power is applied to the GPS component; or
determine, when the threshold is not satisfied, a change-in-height offset value based on the determined slope over the slope period and based on the slope period; and
apply, when the threshold is not satisfied, the change-in-height offset value to a previously determined current height value of the device based on the change-in-height offset value.
8. The system of claim 7 , wherein the device is further to:
enter a wait state based on the wait time.
9. The system of claim 8 , wherein the GPS component includes GPS circuitry.
10. The system of claim 8 , wherein the movement information corresponds to a speed of the device.
11. The system of claim 7 , wherein the determined slope is compared to a first criterion for movement in an ascending direction and a second criterion for movement in a descending direction.
12. A device comprising:
a processor to:
receive barometric pressure data samples from a barometric pressure sensor;
store the barometric pressure data samples in a buffer;
determine that the barometric pressure data samples in the buffer represent data substantially following a transition to a zero slope;
determine, based on determining that the barometric pressure data samples in the buffer represent data substantially following the transition to the zero slope, a slope over a slope period;
apply power to a global positioning system (GPS) component based on the determined slope;
receive a GPS signal based on applying the power to the GPS component;
determine movement information corresponding to the device based on the GPS signal;
determine whether a threshold is satisfied based on the movement information corresponding to the device; and
selectively:
set, when the threshold is satisfied, a wait time that delays reading more barometric pressure data samples from the barometric pressure sensor and delays a next time at which more power is applied to the GPS component; or
determine, when the threshold is not satisfied, an offset value based on the determined slope over the slope period and based on the slope period; and
apply, when the threshold is not satisfied, the offset value to a current height value based on the offset value.
13. The device of claim 12 , wherein the processor is further to:
evaluate the barometric pressure data samples to determine a change in height of the device.
14. The device of claim 12 , wherein the processor is further to:
set to zero a previously determined current height value when the threshold is satisfied.
15. The device of claim 12 , wherein the processor is further to:
enter a wait state for a period, that corresponds to the wait time when the threshold is satisfied.
16. The device of claim 12 , wherein the GPS component includes global positioning circuitry for indicating that at least one of a latitude or a longitude coordinate has changed.
17. The device of claim 12 , wherein the movement information corresponds to a speed of the device.
18. The device of claim 12 , wherein the determined slope is compared to a first criterion for movement in an ascending direction and a second criterion for movement in a descending direction.
19. The device of claim 12 , wherein the barometric pressure sensor is included in one of:
a smartphone,
a user wearable device,
a home improvement device, or
a luggage tracking device.
20. The device of claim 12 , wherein the barometric pressure sensor is included in one of:
a personal emergency response system (PERS), or
a mobile personal emergency response system (PERS).