Variable measurement rate method for positioning systems

• US 8,054,220 B1
• Filed: 12/02/2008
• Issued: 11/08/2011
• Est. Priority Date: 12/20/2006
• Status: Active Grant

• Current Assignee: U-Blox AG (u-blox Holding AG)
• Original Assignee: U-Blox AG (u-blox Holding AG)
• Inventors: Tolson, Nigel J., Watson, Ian G., Tester, David P., Graham, Stephen P.
• Primary Examiner(s): Phan; Dao
• Application Number:
  US12/326,219
• Time in Patent Office: 1,071 Days
• Field of Search: 342/357.4, 342/357.46, 342/357.51, 342/357.74, 701213-215
• US Class Current: 342/357.51
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01S 19/13 Receivers
• CPC Class Codes: G01S 19/34 Power consumption

Abstract

A method of variable rate measurements in a device. The method generally includes the steps of (A) generating an intermediate signal conveying both a position of the device and a velocity of the device in response to a plurality of navigation signals received from external the device, (B) calculating an extrapolated position of the device at a second time based on the position and the velocity both measured at a first time, (C) adjusting an interval between the second time and a third time in response to a difference between the extrapolated position and the position measured at the second time and (D) generating a position signal conveying the position and the velocity, wherein the third time occurs after the second time and the second time occurs after the first time.

Claims

1. A method of variable rate measurements in a device having a position module and a rate module, comprising the steps of:

(A) measuring both a position of said device and a velocity of said device at each of a first time and a second time in response to a plurality of navigation signals received by said position module;

(B) calculating with said rate module an extrapolated value of said position expected at said second time based on both a first value of said position and a first vector of said velocity at said first time; and

(C) adjusting an interval in said rate module between said second time and a third time in response to a difference between said extrapolated value and a second value of said position at said second time.

2. The method according to claim 1, wherein step (C) comprises the sub-step of:

lengthening said interval in response to said difference being less than a minimum threshold.

3. The method according to claim 1, wherein step (C) comprises the sub-step of:

shorting said interval in response to said difference being greater than a maximum threshold.

4. The method according to claim 3, further comprising the step of:

calculating said maximum threshold at said first time as a function of a maximum anticipated acceleration of said device between said first time and said second time.

5. The method according to claim 3, further comprising the step of:

calculating said maximum threshold at said first time as a function of an accuracy value received in an accuracy signal.

6. The method according to claim 1, further comprising the step of:

estimating both a particular value of said position and a particular vector of said velocity at a particular time between said first time and said second time.

7. The method according to claim 1, further comprising the step of:

reducing a power consumption of said device between said first time and said second time.

8. The method according to claim 1, further comprising the step of:

measuring a second vector of said velocity at said second time, wherein adjusting said interval is in further response to said second vector.

9. The method according to claim 1, wherein adjusting said interval is in further response to a maximum anticipated acceleration of said device as determined at said second time.

10. The method according to claim 1, wherein adjusting said interval is in further response to a signal strength used to measure said position, such that said interval becomes longer as said signal strength becomes weaker.

11. The method according to claim 1, further comprising the step of:

reducing a power consumption of said device while said device is stationary for at least a predetermined duration.

12. The method according to claim 1, further comprising the steps of:

setting said interval to a maximum length at a sleep time; and

setting said interval to a normal length at a wake time,

wherein said normal length is shorter than said maximum length.

13. The method according to claim 1, further comprising the steps of:

calculating a minimal time for said device to reach a predefined spatial zone from said first value of said position; and

setting said second time to approximately said minimal time after said first time.

14. A device comprising:

a position module configured to measure both a position of said device and a velocity of said device at each of a first time and a second time in response to a plurality of navigation signals; and

a rate module configured to (i) calculate an extrapolated value of said position expected at said second time based on both a first value of said position and a first vector of said velocity

at said first time and (ii) adjust an interval between said second time and a third time in response to a difference between said extrapolated value and a second value of said position at said second time.

15. The device according to claim 14, further comprising an application module configured to perform at least one of (i) a location-based application and (ii) a location-based service in response to said position.

16. The device according to claim 14, further comprising a motion sensor configured to generate a motion signal conveying a movement of said device, wherein said interval is further adjusted in responsive to said motion signal.

17. The device according to claim 14, further comprising a power module configured to control a power consumption in said device in response to a power signal generated by said rate module.

18. The device according to claim 14, further comprising:

a zone module configured to generate a trigger signal in response to said position; and

an application module responsive to said trigger signal.

19. The device according to claim 14, wherein said device comprises at least one of (i) a cell phone, (ii) a laptop computer, (iii) a palm computer, (iv) a personal digital assistant, (v) a heads-up display and (vi) a digital camera.

20. A device comprising:

means for measuring both a position of said device and a velocity of said device at each of a first time and a second time in response to a plurality of navigation signals; and

means for (i) calculating an extrapolated value of said position expected at said second time based on both a first value of said position and a first vector of said velocity at said first time and (ii) adjusting an interval between said second time and a third time in response to a difference between said extrapolated value and a measured value of said position at said second time.