Location and path-map generation data acquisition and analysis systems

• US 8,577,595 B2
• Filed: 07/17/2008
• Issued: 11/05/2013
• Est. Priority Date: 07/17/2008
• Status: Active Grant

• Current Assignee: Memsic Semiconductor (Wuxi) Co., Ltd. (MZ Investment Holdings Ltd.)
• Original Assignee: Memsic Incorporated (MZ Investment Holdings Ltd.)
• Inventors: Zhao, Yang, Liang, Jin
• Primary Examiner(s): Zeender, Ryan
• Assistant Examiner(s): Wilder, Hunter
• Application Number:
  US12/218,765
• Publication Number:
  US 20100017124A1
• Time in Patent Office: 1,937 Days
• Field of Search: 701/212, 701/220, 340/435, 382/106, 382/107, 382/103, 382/154, 396/153
• US Class Current: 701/408
• CPC Class Codes: G01C 21/1654 with electromagnetic compass
• CPC Class Codes: G01C 21/1656 with passive imaging devices, e.g. cameras
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01C 21/26 specially adapted for navigation in a road network
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/30252 Vehicle exterior; Vicinity of vehicle
• CPC Class Codes: G06T 7/73 using feature-based methods

Abstract

A device, system, and method for generating location and path-map data for displaying a location and path-map is disclosed. The device includes a first set of sensors for generating a plurality of first data signals with respect to an attitude of an object; a second set of sensors for generating a plurality of second data signals with respect to the attitude of the object; an imaging device for generating a plurality of third data signals that include a most significant feature, which is disposed in at least two images of the imaging device; and at least one processing device that is adapted to calculate a heading direction (bearing) of the device using the plurality of first data signals and the plurality of second data signals; to calculate a distance traveled along the heading direction using the plurality of third data signals; and to translate the calculated heading direction and calculated distance traveled into a leg or portion of a leg of a path-map for visual display on a two- or three-dimensional system.

Claims

1. A device for generating location and path-map data for displaying a location and path-map of an object in motion, the device comprising:

a first set of magnetic sensors for generating a plurality of first data signals with respect to an attitude of the object;

a first set of inertial sensors for generating a plurality of second data signals with respect to the attitude of the object;

an imaging device for generating a plurality of temporally-spaced images; and

at least one processing device that is adapted to;

calculate a first heading direction (bearing) of a first path along which the object is traveling using the plurality of first data signals and the plurality of second data signals;

while the object is still in motion along the first heading direction, identify a first image taken at a first location on the first path and a temporally subsequent second image taken at a second location on the first path;

identify a most significant feature in the first image in common with the temporally subsequent second image;

calculate a demagnification number using a relationship between at least one dimension of the most significant feature in the first image and the at least one dimension of said most significant feature in the second image;

calculate a distance traveled by the object along the first path in the first heading direction using the calculated demagnification number; and

translate the calculated heading direction and calculated distance traveled into a leg or portion of a leg of a path-map for visual display on a two- or three-dimensional system.

2. The device as recited in claim 1, wherein the first set of magnetic sensors includes a set of magnetic sensors that are structured and arranged to generate the plurality of first data signals corresponding to magnetic field strength about three orthogonal axes.

3. The device as recited in claim 1, wherein the first set of inertial sensors includes a set of inertial sensors that are structured and arranged to generate the plurality of second data signals corresponding to accelerations along two or three orthogonal axes.

4. The device as recited in claim 1, wherein the imaging device is structured and arranged to generate the plurality of images at a predetermined, fixed frequency.

5. The device as recited in claim 1, wherein the at least one processing device includes:

a signal processing device that is electrically coupled to the first set of magnetic sensors and the first set of inertial sensors; and

an image processing device that is electrically coupled to the imaging device and to the signal processing device.

6. The device as recited in claim 5, wherein the at least one processing device further includes a main controller that is electrically coupled to each of the signal processing device and the image processing device.

7. The device as recited in claim 1, wherein the first set of magnetic sensors includes a three-axis electronic compass.

8. The device as recited in claim 1, wherein the first set of inertial sensors includes a two- or three-axis accelerometer.

9. The device as recited in claim 1, wherein the at least one processing device calculates heading direction (α

) using the equation;

α

=tan<sup>−

1</sup>(M_yh / M_xh)

where M_xh=M_x·

cos φ

+M_y·

sin θ

·

sin φ

+M_z·

cos θ

·

sin φ

and M_yh=M_y·

cos θ

−

M_z·

sin θ

,

in which M_xh refers to the magnetic field strength about the x-axis in a horizontal plane;

M_yh refers to the magnetic field strength about the y-axis in the horizontal plane;

θ

(theta) is the roll of the object and φ

(phi) is the pitch of the object.

10. The device as recited in claim 1, wherein the at least one processing device translates the calculated heading direction and the calculated distance traveled into a leg vector or portion of a leg vector.

11. A method of providing data for generating and displaying a location or path-map on a device or system while an object is in motion, the method comprising:

generating a plurality of first data signals with respect to an attitude of the object;

generating a plurality of second data signals with respect to the attitude of the object;

generating a plurality of temporally-spaced images using an imaging device;

calculating a first heading direction (bearing) of a first path along which the object is traveling using the plurality of first data signals and the plurality of second data signals;

while the object is still in motion along the first heading direction, identifying a first image taken by the imaging device at a first location on the first path and a temporally subsequent second image taken by the imaging device at a second location on the first path;

identifying a most significant feature in the first image in common with the temporally subsequent second image;

calculating a demagnification number using a relationship between at least one dimension of the most significant feature in the first image and the at least one dimension of said most significant feature in the second image;

calculating a distance traveled by the object along the first path in the first heading direction using the calculated demagnification number; and

translating the calculated heading direction and calculated distance traveled into a leg or portion of a leg of a path-map for visual display on the device or system.

12. The method as recited in claim 11, wherein generating the first data signals includes generating data signals corresponding to magnetic field strength about three orthogonal axes using magnetic sensors.

13. The method as recited in claim 11, wherein generating the second data signals includes generating data signals corresponding to accelerations along two or three orthogonal axes using inertial sensors.

14. The method as recited in claim 11, wherein generating the images occurs at a predetermined, fixed frequency.

15. The method as recited in claim 11, wherein heading direction (a) is calculated using the equation:

α

=tan<sup>−

1</sup>(M_yh / M_xh)

where M_xh=M_x·

cos φ

+M_y·

sin θ

·

sin φ

+M_z·

cos θ

·

sin φ

and M_yh=M_y·

cos θ

−

M_z·

sin θ

,

in which M_xh refers to the magnetic field strength about the x-axis in a horizontal plane;

M_yh refers to the magnetic field strength about the y-axis in the horizontal plane;

θ

(theta) is the roll of the object and φ

(phi) is the pitch of the object.

16. The method as recited in claim 11, further comprising:

determining when an appreciable change in at least one of heading direction (bearing), magnetic field strength, and acceleration occurs; and

upon determination of the appreciable change;

identifying a second most significant feature common to a third image and a temporally successive fourth image; and

calculating a second demagnification number using a relationship between at least one dimension of the second most significant feature in the third image and the at least one dimension of the second most significant feature in the fourth image.

17. A system for displaying location and path-map data of an object in motion, the system comprising:

a first set of magnetic sensors for generating a plurality of first data signals with respect to an attitude of the object;

a first set of inertial sensors for generating a plurality of second data signals with respect to the attitude of the object;

an imaging device for generating a plurality of temporally-spaced images;

a first processing device that is adapted to calculate a first heading direction (bearing) of a first path along which the object is traveling using the plurality of first data signals and the plurality of second data signals;

a second processing device that is adapted to;

while the object is still in motion along the first heading direction, identify a first image taken at a first location on the first path and a temporally subsequent second image taken at a second location on the first path;

identify a most significant feature in the first image in common with the temporally subsequent second image;

calculate a demagnification number using a relationship between at least one dimension of the most significant feature in the first image and the at least one dimension of said most significant feature in the second image; and

calculate a distance traveled by the object along the first path in the first heading direction using the calculated demagnification number;

a third processing device that is adapted to translate the calculated heading direction and the calculated distance traveled into a leg or portion of a leg of a path-map; and

a two- or three-dimensional display screen for displaying the leg or leg portion.