Construction of a surface of best GPS visibility from passive traces using SLAM for horizontal localization and GPS readings and barometer readings for elevation estimation

• US 10,240,995 B2
• Filed: 04/23/2015
• Issued: 03/26/2019
• Est. Priority Date: 08/01/2014
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google LLC (Alphabet Inc.)
• Inventors: Le Grand, Etienne, Khider, Mohammed
• Primary Examiner(s): Barbee, Manuel L
• Assistant Examiner(s): Nimox, Raymond L
• Application Number:
  US14/694,240
• Publication Number:
  US 20160033266A1
• Time in Patent Office: 1,433 Days
• CPC Class Codes: G01L 19/0092 Pressure sensor associated with other sensors, e.g. for measuring acceleration or temperature G01L9/025, G01L9/045, G01L9/065, G01L9/085, G01L9/105, G01L9/125, G01L19/02, G01L19/04 take precedence; measuring two or more variable G01D21/02; temperature sensors with pressure compensation G01K1/26
• CPC Class Codes: G01S 19/01 Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
• CPC Class Codes: G01S 19/48 by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system

Abstract

A system includes one or more processors, and data storage configured to store instructions that, when executed by the one or more processors, cause the system to perform functions. In one example, the functions include receiving logs of data, wherein respective data in the received logs of data are collected by one or more sensors of a device over one or more locations and over a time period. In the present example, the functions also include determining location estimates of the device by performing a simultaneous localization and mapping (SLAM) optimization of the location estimates using barometer data and GPS elevational data available in the logs of data, wherein the location estimates indicate elevational locations of the device over the time period.

Claims

1. A system comprising:

a device comprising a barometer; and

a computing device comprising;

one or more processors; and

data storage configured to store instructions that, when executed by the one or more processors, cause the computing device to perform functions comprising;

receiving logs of data, wherein respective data in the received logs of data are collected by one or more sensors of the device over one or more locations in a three-dimensional area and over a time period; and

performing a simultaneous localization and mapping (SLAM) optimization, wherein performing the SLAM optimization comprises;

determining a series of horizontal locations of the device using GPS positioning data available in the received logs of data as a constraint, wherein each of the horizontal locations comprises a latitudinal value and a longitudinal value;

determining a corresponding series of elevation locations of the device using GPS elevation data available in the received logs of data as an absolute elevation constraint and barometer data available in the received logs of data as a relative elevation constraint; and

generating a map of the three-dimensional area and a path that the device traversed through the three-dimensional area over the time period,

wherein the path of the device comprises the series of horizontal locations of the device and the corresponding series of elevation locations of the device,

wherein the map of the three-dimensional area and the path of the device are generated simultaneously, and

wherein the device is configured to calibrate the barometer based on the map of the three-dimensional area or the path of the device.

2. The system of claim 1,

wherein the functions further comprise selecting, for use in the SLAM optimization, logs of data from the received logs of data, and

wherein the selected logs of data include barometer data associated with GPS elevation data.

3. The system of claim 2, wherein performing the SLAM optimization further comprises horizontally localizing the selected logs of data.

4. The system of claim 3, wherein horizontally localizing the selected logs of data comprises using the GPS elevation data as a constraint.

5. The system of claim 1,

wherein the functions further comprise defining a surface of GPS visibility greater than a predetermined visibility threshold,

wherein the surface of GPS visibility greater than the predetermined visibility threshold corresponds to a ground level surface, and

wherein determining the corresponding series of elevation locations of the device comprises determining the corresponding series of elevation locations of the device using the surface of GPS visibility greater than the predetermined visibility threshold as a constraint.

6. The system of claim 4,

wherein performing the SLAM optimization further comprises using a smoothing constraint,

wherein the smoothing constraint limits an elevation change between adjacent horizontal locations in the selected logs of data, and

wherein the smoothing constraint specifies that elevation locations at adjacent horizontal locations are similar.

7. The system of claim 1,

wherein the map of the three-dimensional area is a first map, the path of the device is a first path, the GPS positioning data is first GPS positioning data available in the received logs of data, the barometer data is first barometer data available in the received logs of data, the GPS elevation data is first GPS elevation data available in the received logs of data, the series of horizontal locations is a first series of horizontal locations of the device, the corresponding series of elevation locations is a first corresponding series of elevation locations of the device, and the SLAM optimization is a first SLAM optimization, and

wherein the functions further comprise performing a second SLAM optimization, wherein performing the second SLAM optimization comprises:

determining a second series of horizontal locations of the device using second GPS positioning data available in the received logs of data as a constraint, wherein each of the horizontal locations in the second series of horizontal locations of the device comprises a latitudinal value and a longitudinal value;

determining a second corresponding series of elevation locations of the device using second GPS elevation data available in the received logs of data as an absolute elevation constraint and second barometer data available in the received logs of data as a relative elevation constraint; and

generating a second map of the three-dimensional area and a second path of the device,

wherein the second path of the device comprises the second series of horizontal locations of the device and the second corresponding series of elevation locations of the device,

wherein the second map of the three-dimensional area and the second path of the device are generated simultaneously, and

wherein the device is configured to calibrate the barometer based on the second map of the three-dimensional area or the second path of the device.

8. A method comprising:

receiving logs of data, wherein respective data in the received logs of data are collected by one or more sensors of a device, including a barometer of the device, over one or more locations in a three-dimensional area and over a time period;

performing a simultaneous localization and mapping (SLAM) optimization, wherein performing the SLAM optimization comprises;

determining a series of horizontal locations of the device using GPS positioning data available in the received logs of data as a constraint, wherein each of the horizontal locations comprises a latitudinal value and a longitudinal value;

determining a corresponding series of elevation locations of the device using GPS elevation data available in the received logs of data as an absolute elevation constraint and barometer data available in the received logs of data as a relative elevation constraint; and

generating a map of the three-dimensional area and a path that the device traversed through the three-dimensional area over the time period, wherein the path of the device comprises the series of horizontal locations of the device and the corresponding series of elevation locations of the device, and

wherein the map of the three-dimensional area and the path of the device are generated simultaneously; and

recalibrating the barometer of the device based on the map of the three-dimensional area or the path of the device.

9. The method of claim 8, further comprising selecting, for use in the SLAM optimization, logs of data from the received logs of data, wherein the selected logs of data include barometer data associated with GPS elevation data.

10. The method of claim 9, wherein performing the SLAM optimization further comprises horizontally localizing the selected logs of data.

11. The method of claim 10, wherein horizontally localizing the selected logs of data comprises using the GPS elevation data as a constraint.

12. The method of claim 8, further comprising defining a surface of GPS visibility greater than a predetermined visibility threshold,

wherein the surface of GPS visibility greater than the predetermined visibility threshold corresponds to a ground level surface, and

wherein determining the corresponding series of elevation locations of the device comprises determining the corresponding elevation locations of the device using the surface of GPS visibility greater than the predetermined visibility threshold as a constraint.

13. The method of claim 11,

wherein performing the SLAM optimization further comprises using a smoothing constraint,

wherein the smoothing constraint limits an elevation change between adjacent horizontal locations in the selected logs of data, and

wherein the smoothing constraint specifies that elevation location values at adjacent horizontal locations are similar.

14. The method of claim 8,

wherein the map of the three-dimensional area is a first map, the path of the device is a first path, the GPS positioning data is first GPS positioning data available in the received logs of data, the barometer data is first barometer data available in the received logs of data, the GPS elevation data is first GPS elevation data available in the received logs of data, the series of horizontal locations is a first series of horizontal locations of the device, the corresponding series of elevation locations is a first corresponding series of elevation locations of the device, and the SLAM optimization is a first SLAM optimization, and

wherein the method further comprises performing a second SLAM optimization, wherein performing the second SLAM optimization comprises:

determining a second series of horizontal locations of the device using second GPS positioning data available in the received logs of data as a constraint, wherein each of the horizontal locations in the second series of horizontal locations of the device comprises a latitudinal value and a longitudinal value;

determining a second corresponding series of elevation locations of the device using second GPS elevation data available in the received logs of data as an absolute elevation constraint and second barometer data available in the received logs of data as a relative elevation constraint; and

generating a second map of the three-dimensional area and a second path of the device,

wherein the second path of the device comprises the second series of horizontal locations of the device and the second corresponding series of elevation locations of the device,

wherein the second map of the three-dimensional area and the second path of the device are generated simultaneously, and

wherein the device is configured to calibrate the barometer based on the second map of the three-dimensional area or the second path of the device.

15. A non-transitory computer-readable medium having stored therein instructions that, when executed by one or more processors, cause the one or more processors to perform functions comprising:

receiving logs of data, wherein respective data in the received logs of data are collected by one or more sensors of a device, including a barometer of the device, over one or more locations in a three-dimensional area and over a time period; and

performing a simultaneous localization and mapping (SLAM) optimization, wherein performing the SLAM optimization comprises;

determining a series of horizontal locations of the device using GPS positioning data available in the received logs of data as a constraint, wherein each of the horizontal locations comprises a latitudinal value and a longitudinal value;

determining a corresponding series of elevation locations of the device using GPS elevation data available in the received logs of data as an absolute elevation constraint and barometer data available in the received logs of data as a relative elevation constraint; and

generating a map of the three-dimensional area and a path that the device traversed through the three-dimensional area over the time period,

wherein the path of the device comprises the series of horizontal locations of the device and the corresponding series of elevation locations of the device,

wherein the map of the three-dimensional area and the path of the device are generated simultaneously, and

wherein the device is configured to calibrate the barometer based on the map of the three-dimensional area or the path of the device.

16. The non-transitory computer-readable medium of claim 15,

wherein the functions further comprise selecting, for use in the SLAM optimization, logs of data from the received logs of data, and

wherein the selected logs of data include barometer data associated with GPS elevation data.

17. The non-transitory computer-readable medium of claim 16, wherein performing the SLAM optimization comprises horizontally localizing the selected logs of data.

18. The non-transitory computer-readable medium of claim 17, wherein horizontally localizing the selected logs of data comprises using the GPS elevation data as a constraint.

19. The non-transitory computer-readable medium of claim 15,

wherein the functions further comprise defining a surface of GPS visibility greater than a predetermined visibility threshold,

wherein the surface of GPS visibility greater than the predetermined visibility threshold corresponds to a ground level surface, and

wherein determining the corresponding series of elevation locations of the device comprises determining the corresponding series of elevation locations of the device using the surface of GPS visibility greater than the predetermined visibility threshold as a constraint.

20. The non-transitory computer-readable medium of claim 18,

wherein performing the SLAM optimization further comprises using a smoothing constraint,

wherein the smoothing constraint limits an elevation change between adjacent horizontal locations in the selected logs of data, and

wherein the smoothing constraint specifies that elevation location values at adjacent horizontal locations are similar.