INTERRUPTION FREE NAVIGATOR

• US 20030176970A1
• Filed: 03/15/2002
• Published: 09/18/2003
• Est. Priority Date: 03/15/2002
• Status: Active Grant

• Current Assignee: American GNC Corporation
• Original Assignee: American GNC Corporation
• Inventors: Lin, Ching-Fang
• Granted Patent: US 6,658,354 B2
• Time in Patent Office: Days
• US Class Current: 701/214
• CPC Class Codes: G01C 21/1652 with ranging devices, e.g. LIDAR or RADAR
• CPC Class Codes: G01C 21/1654 with electromagnetic compass
• CPC Class Codes: G01C 21/1656 with passive imaging devices, e.g. cameras

Abstract

An interruption free navigator includes an inertial measurement unit, a north finder, a velocity producer, a positioning assistant, a navigation processor, an altitude measurement, an object detection system, a wireless communication device, and a display device and map database. Output signals of the inertial measurement unit, the velocity producer, the positioning assistant, the altitude measurement, the object detection system, and the north finder are processed to obtain highly accurate position measurements of the person. The user'"'"'s position information can be exchanged with other users through the wireless communication device, and the location and surrounding information can be displayed on the display device by accessing a map database with the person position information.

Claims

1. An interruption free navigator, comprising:

a main IMU based interruption-free positioning module is utilized for sensing motion measurements of said user and producing interruption-free positioning data of said user;

a positioning assistant providing interruptible positioning data to assist said main IMU based interruption-free positioning module to achieve an improved interruption-free positioning data of said user; and

a wireless communication device being built in for exchanging said improved interruption-free positioning data with other users.

2. The interruption free navigator, as recited in claim 1, further comprises an altitude measurement device producing an altitude measurement to improve vertical positioning performance of said main IMU based interruption-free positioning module.

3. The interruption free navigator, as recited in claim 1, further comprises an object detection system to capture images of a surrounding environment of said user and to derive position data of adjacent objects of said user, so as to provide a notice that an interested object has been found in neighborhood.

4. The interruption free navigator, as recited in claim 2, further comprises an object detection system to capture images of a surrounding environment of said user and to derive position data of adjacent objects of said user, so as to provide a notice that an interested object has been found in neighborhood.

5. The interruption free navigator, as recited in claim 1, further comprising a display device for visualizing said interruption-free positioning data of said user using said surrounding map information.

6. The interruption free navigator, as recited in claim 5, further comprising a map database providing map data to obtain surrounding map information of location of said user by accessing said map database using said interruption-free positioning data.

7. The interruption free navigator, as recited in claim 2, further comprising a display device for visualizing said interruption-free positioning data of said user using said surrounding map information.

8. The interruption free navigator, as recited in claim 7, further comprising a map database providing map data to obtain surrounding map information of location of said user by accessing said map database using said interruption-free positioning data.

9. The interruption free navigator, as recited in claim 3, further comprising a display device for visualizing said interruption-free positioning data of said user using said surrounding map information.

10. The interruption free navigator, as recited in claim 9, further comprising a map database providing map data to obtain a surrounding map information of location of said user by accessing said map database using said interruption-free positioning data.

11. The interruption free navigator, as recited in claim 4, further comprising a display device for visualizing said interruption-free positioning data of said user using said surrounding map information.

12. The interruption free navigator, as recited in claim 11, further comprising a map database providing map data to obtain a surrounding map information of location of said user by accessing said map database using said interruption-free positioning data.

13. The interruption free navigator, as recited in claim 2, wherein said main IMU based interruption-free positioning module further comprises an altitude interface and processing board for converting said altitude measurement from said altitude measurement device into digital data of platform height over mean sea level (MSL).

14. The interruption free navigator, as recited in claim 4, wherein said main IMU based interruption-free positioning module further comprises an altitude interface and processing board for converting said altitude measurement from said altitude measurement device into digital data of platform height over mean sea level (MSL).

15. The interruption free navigator, as recited in claim 7, wherein said main IMU based interruption-free positioning module further comprises an altitude interface and processing board for converting said altitude measurement from said altitude measurement device into digital data of platform height over mean sea level (MSL).

16. The interruption free navigator, as recited in claim 8, wherein said main IMU based interruption-free positioning module further comprises an altitude interface and processing board for converting said altitude measurement from said altitude measurement device into digital data of platform height over mean sea level (MSL).

17. The interruption free navigator, as recited in claim 11, wherein said main IMU based interruption-free positioning module further comprises an altitude interface and processing board for converting said altitude measurement from said altitude measurement device into digital data of platform height over mean sea level (MSL).

18. The interruption free navigator, as recited in claim 12, wherein said main IMU based interruption-free positioning module further comprises an altitude interface and processing board for converting said altitude measurement from said altitude measurement device into digital data of platform height over mean sea level (MSL).

19. The interruption free navigator, as recited in claim 3, wherein said main IMU based interruption-free positioning module further comprises an object detection system interface and processing board to provide a data processing and interfacing for said object detection system.

20. The interruption free navigator, as recited in claim 4, wherein said main IMU based interruption-free positioning module further comprises an object detection system interface and processing board to provide a data processing and interfacing for said object detection system.

21. The interruption free navigator, as recited in claim 9, wherein said main IMU based interruption-free positioning module further comprises an object detection system interface and processing board to provide a data processing and interfacing for said object detection system.

22. The interruption free navigator, as recited in claim 10, wherein said main IMU based interruption-free positioning module further comprises an object detection system interface and processing board to provide a data processing and interfacing for said object detection system.

23. The interruption free navigator, as recited in claim 11, wherein said main IMU based interruption-free positioning module further comprises an object detection system interface and processing board to provide a data processing and interfacing for said object detection system.

24. The interruption free navigator, as recited in claim 12, wherein said main IMU based interruption-free positioning module further comprises an object detection system interface and processing board to provide a data processing and interfacing for said object detection system.

25. The interruption free navigator, as recited in claim 14, wherein said main IMU based interruption-free positioning module further comprises an object detection system interface and processing board to provide a data processing and interfacing for said object detection system.

26. The interruption free navigator, as recited in claim 17, wherein said main IMU based interruption-free positioning module further comprises an object detection system interface and processing board to provide a data processing and interfacing for said object detection system.

27. The interruption free navigator, as recited in claim 1, 2, 3, 4, 5, 16, 18, 22, or 24, wherein said main IMU based interruption-free positioning module comprises:

an inertial measurement unit (IMU) for sensing said traveling displacement motions of said user so as to produce digital angular increments and velocity increments data in response to said user motion;

a north finder producing said heading measurement of said user.

a velocity producer producing velocity data in a body frame of said user;

a navigation processor connected with said inertial measurement unit, said north finder, said velocity producer, and said positioning assistant, so as to receive said digital angular increments and velocity increments data, said heading measurement, said velocity data in said body frame, and the interruptible positioning data from said positioning assistant to produce IMU position, velocity, and attitude data, and an optimal estimate of errors of said IMU position, velocity, and attitude data for correcting said IMU position, velocity, and attitude data error to output corrected IMU position, velocity and attitude data.

28. The interruption free navigator, as recited in claim 27, wherein said navigation processor utilizes an inertial navigation processing module for producing said IMU position, velocity, and attitude data, and an optimal filtering module for producing said optimal estimate of errors of said IMU position, velocity, and attitude data.

29. The interruption free navigator, as recited in claim 27, wherein said north finder is used to measure a heading angle of said user and said velocity producer is used to measure a relative velocity with respect to a ground.

30. The interruption free navigator, as recited in claim 27, wherein said navigation processor provides an integration Kalman filter to estimate and compensate INS errors and sensor errors.

31. The interruption free navigator, as recited in claim 29, wherein said navigation processor provides an integration Kalman filter to estimate and compensate INS errors and sensor errors.

32. The interruption free navigator, as recited in claim 29, wherein said velocity producer provides relative velocity measurements of said user to said ground by sensing Doppler frequencies by means of a Doppler effect which is a shift in a frequency of a wave radiated from said velocity produce when reflected by said ground in motion.

33. The interruption free navigator, as recited in claim 31, wherein said velocity producer provides relative velocity measurements of said user to said ground by sensing Doppler frequencies by means of a Doppler effect which is a shift in a frequency of a wave radiated from said velocity producer when reflected by said ground in motion.

34. The interruption free navigator, as recited in claim 1, 2, 3, 4, 5, 16, 18, 22, or 24, wherein said positioning assistant includes a GPS receiver to receive interruptible GPS RF (radio frequency) signals to produce GPS positioning data to said navigation processor.

35. The interruption free navigator, as recited in claim 34, wherein said positioning assistant further includes a data link for receiving said GPS positioning data from a GPS reference site to perform differential GPS positioning.

36. The interruption free navigator, as recited in claim 35, wherein said navigation processor further provides:

a new satellites/cycle slips detection module for receiving said GPS measurements from said GPS receiver and GPS reference measurement from said data link and determines whether new GPS satellites come in view or cycle slips occur; and

an on-the-fly ambiguity resolution module for receiving said GPS measurements from said GPS receiver and GPS reference measurement from said data link and is activated when either new GPS satellites come in view or cycle slips occur to fix said ambiguity integer.

37. The interruption free navigator, as recited in claim 36, wherein said on-the-fly ambiguity resolution module is activated when said new satellites/cycle slips detection module is on, and therefore, rover raw and Doppler shift measurements from said GPS receiver and reference raw measurements, Doppler shift measurements, position, and velocity from said data link to fix said integer ambiguities.

38. The interruption free navigator, as recited in claim 37, wherein said on-the-fly ambiguity resolution module, comprising the steps of:

(1) initiating an on-the-fly ambiguity resolution module as said new satellites/cycle slips detection module is on, i.e., said new satellites or cycle slips occur;

(2) fixing integer ambiguities to estimate a more accurate user navigation solution, and

(3) sending said selected integer ambiguities from said on-the-fly ambiguity resolution module to said integration Kalman filter.

39. The interruption free navigator, as recited in claim 38, wherein said step (3) further comprises said steps of:

(3.1) using intermediate ambiguity search strategy (IASS) and estimator bank to set up ambiguity set and determine said ambiguity integer; and

(3.2) validating and confirming said ambiguity integer.

40. The interruption free navigator, as recited in claim 31, wherein said navigation processor further provides:

an INS computation module, using said digital angular increments and velocity increments signals from said IMU to produce said inertial positioning measurements, including said IMU position, velocity, and attitude data;

a magnetic sensor processing module for producing said heading angle; and

a velocity processing module for producing relative position error measurements for said integration Kalman filter.

41. The interruption free navigator, as recited in claim 40, wherein said INS computation module further comprises:

a sensor compensation module for calibrating errors of said digital angular increments and velocity increments signals, which is not proportional to said user'"'"'s motion; and

an inertial navigation algorithm module for computing said IMU position, velocity, and attitude data using said compensated said digital angular increments and velocity increments signals.

42. The interruption free navigator, as recited in claim 41, wherein said inertial navigation algorithm module further comprises:

an attitude integration module for integrating said angular increments into attitude data;

a velocity integration module for transforming measured velocity increments into a suitable navigation coordinate frame by using said attitude data, wherein said transformed velocity increments are integrated into velocity data; and

a position module for integrating said navigation frame velocity data into position data.

43. The interruption free navigator, as recited in claim 42, wherein said magnetic sensor processing module for producing said heading angle further comprises:

a hard iron compensation module for receiving a digital Earth'"'"'s magnetic field vector and compensating hard iron effects in said digital earth'"'"'s magnetic field vector;

a soft iron compensation module for compensating soft iron effects in said digital earth'"'"'s magnetic field vector; and

a heading computation module for receiving said digital Earth'"'"'s magnetic field vector and pitch and roll from said inertial navigation algorithm module and computing said heading data.

44. The interruption free navigator, as recited in claim 43, wherein said velocity producer processing module further comprises:

a scale factor and misalignment error compensation module for compensating said scale factor and misalignment errors in a Doppler velocity;

a transformation module for transforming an input Doppler velocity data expressed in said body frame to said Doppler velocity expressed in said navigation frame; and

a relative position computation for receiving said IMU velocity and attitude data and said Doppler velocity to form said relative position measurements for said integration Kalman filter.

45. The interruption free navigator, as recited in claim 44, wherein said integration Kalman filter provides:

a motion test module for determining if said user stops automatically;

a GPS integrity monitor for determining if said GPS data is available;

a state estimation module for filtering said measurements and obtaining optimal estimates of IMU positioning errors; and

a measurement and time varying matrix formation module for formulating said measurement and time varying matrix for said state estimation module according to a motion status of said user from said motion test module and GPS data availability from said GPS integrity monitor.

46. The interruption free navigator, as recited in claim 45, wherein said state estimation module provides a horizontal filter for obtaining estimates of horizontal IMU positioning errors, and a vertical filter for obtaining said estimates of vertical IMU positioning errors.

47. The interruption free navigator, as recited in claim 46, wherein said state estimation module from time to time receives a known position obtained from said GPS receiver, a known position change obtained from said velocity processing module, a position change equal to zero obtained from said zero velocity update processing from said motion tests module, and a known heading obtained from said magnetic sensor processing module.

48. The interruption free navigator, as recited in claim 36, wherein said motion test module provides:

a velocity producer change test module for receiving said velocity producer reading to determining if said user stops or restarts;

a system velocity change test module for comparing system velocity change between a current interval and said previous interval to determine if said user stops or restarts;

a system velocity test module for comparing a system velocity magnitude with a predetermined value to determine whether said user stops or restarts; and

an attitude change test module for comparing said system attitude magnitude with a predetermined value to determine whether said user stops or restarts.

49. An interruption-free hand-held positioning method, comprising the steps of:

(a) sensing motion measurements of said user by a main IMU (Inertial Measurement Unit) to produce digital angular increments and velocity increments signals in response to a user motion,

(b) providing interruptible positioning data to assist said main IMU based interruption-free positioning module by a positioning assistant,

(c) producing interruption-free positioning data of said user using motion measurements, and improving said interruption-free positioning data of said user when said interruptible positioning data is available, and

(d) exchanging said interruption-free positioning data with other users by a wireless communication device.

50. The interruption-free hand-held positioning method, as recited in claim 49, before the step (d), further comprising a step of providing altitude measurement and converting the altitude measurement into digital data of platform height over a mean sea level.

51. The interruption-free hand-held positioning method, as recited in claim 49, further comprising a step of capturing images of a surrounding environment of the user for deriving the position data of adjacent objects, so as to provide a notice that an interested object has been found in neighborhood.

52. The interruption-free hand-held positioning method, as recited in claim 50, further comprising a step of capturing images of a surrounding environment of the user for deriving the position data of adjacent objects, so as to provide a notice that an interested object has been found in neighborhood.

53. The interruption-free hand-held positioning method, as recited in claim 50, after the step (d), further comprising the step of:

(e) providing map data to obtain a surrounding map information of location of said user by accessing a map database using said improved interruption-free positioning data, and

(f) visualizing said interruption-free positioning data of said user using said surrounding map information by a display device.

54. The interruption-free hand-held positioning method, as recited in claim 51, after the step (d), further comprising the step of:

(e) providing map data to obtain a surrounding map information of location of said user by accessing a map database using said improved interruption-free positioning data, and

(f) visualizing said interruption-free positioning data of said user using said surrounding map information by a display device.

55. The interruption-free hand-held positioning method, as recited in claim 52, after the step (d), further comprising the step of:

(e) providing map data to obtain a surrounding map information of location of said user by accessing a map database using said improved interruption-free positioning data, and

(f) visualizing said interruption-free positioning data of said user using said surrounding map information by a display device.

56. The interruption-free hand-held positioning method, as recited in claim 50, 51, 52, 53, 54, or 55, wherein the step (c) comprises the steps of:

(c.1) sensing an earth'"'"'s magnetic field to measure a heading angle of said user by a magnetic sensor,

(c.2) measuring a relative velocity of said user relative to a ground by a velocity producer to produce a measured velocity, and

(c.3) blending said digital angular increments and velocity increments signals, said heading angle, said relative velocity of said user relative to said ground, and said GPS positioning data to produce optimal positioning data.

57. The interruption-free hand-held positioning method, as recited in claim 56, after the step (f), further comprising a step (g) of aiding a code and carrier phase tracking processing of said GPS signals with velocity and acceleration data to improve an anti-jamming and high-dynamics capability of said GPS receiver.

58. The interruption-free hand-held positioning method, as recited in claim 56, wherein the step (c.3) further comprises the steps of:

c.3.1 computing inertial positioning measurements using said digital angular increments and velocity increments signals;

c.3.2 computing said heading angle using said earth'"'"'s magnetic field measurements,

c.3.3 creating relative position error measurements in said velocity producer processing module using said relative velocity of said user relative to said ground for a Kalman filter, and

c.3.4 estimating errors of inertial positioning measurements by means of performing Kalman filtering computation to calibrate said inertial positioning measurements.

59. The interruption-free hand-held positioning method, as recited in claim 56, wherein the step (c.3) further comprises the steps of:

c.3.1 computing inertial positioning measurements using said digital angular increments and velocity increments signals;

c.3.2 computing said heading angle using said earth'"'"'s magnetic field measurements,

c.3.3 creating relative position error measurements in said velocity producer processing module using said relative velocity of said user relative to said ground for a Kalman filter, and

c.3.4 estimating errors of inertial positioning measurements by means of performing Kalman filtering computation to calibrate said inertial positioning measurements.

60. The interruption-free hand-held positioning method, as recited in claim 58, wherein the step (c.3.1) further comprises the steps of:

c.3.1.1 integrating said angular increments into attitude data, referred to as attitude integration processing;

c.3.1.2 transforming said measured velocity increments into a suitable navigation coordinate frame by use of said attitude data, wherein said transferred velocity increments are integrated into velocity data, denoted as velocity integration processing, and

c.3.1.3 integrating said velocity data into position data, denoted as position integration processing.

61. The interruption-free hand-held positioning method, as recited in claim 59, wherein the step (c.3.1) further comprises the steps of:

c.3.1.1 integrating said angular increments into attitude data, referred to as attitude integration processing;

c.3.1.2 transforming said measured velocity increments into a suitable navigation coordinate frame by use of said attitude data, wherein said transferred velocity increments are integrated into velocity data, denoted as velocity integration processing, and

c.3.1.3 integrating said velocity data into position data, denoted as position integration processing.

62. The interruption-free hand-held positioning method, as recited in claim 58, wherein the step (c.3.4) further comprises the steps of:

c.3.4.1 performing motion tests to determine whether said user stops to initiate a zero-velocity update;

c.3.4.2 determining whether GPS data available using a GPS state status indicator from said GPS receiver;

c.3.4.3 formulating measurement equations and time varying matrix for said Kalman filter; and

c.3.4.4 computing estimates of error states using said Kalman filter.

63. The interruption-free hand-held positioning method, as recited in claim 59, wherein the step (c.3.4) further comprises the steps of:

c.3.4.1 performing motion tests to determine whether said user stops to initiate a zero-velocity update;

c.3.4.2 determining whether GPS data available using a GPS state status indicator from said GPS receiver;

c.3.4.3 formulating measurement equations and time varying matrix for said Kalman filter; and

c.3.4.4 computing estimates of error states using said Kalman filter.

64. The interruption-free hand-held positioning method, as recited in claim 56, wherein the step (c.2) further comprises the steps of:

(c.2.1) transforming said measured velocity expressed in a body frame into a navigation frame;

(c.2.2) comparing said measured velocity with an IMU velocity to form a velocity difference; and

(c.2.3) integrating said velocity difference during a predetermined interval.

65. The interruption-free hand-held positioning method, as recited in claim 62. wherein the step (c.2) further comprises the steps of:

(c.2.1) transforming said measured velocity expressed in a body frame into a navigation frame;

(c.2.2) comparing said measured velocity with an IMU velocity to form a velocity difference; and

(c.2.3) integrating said velocity difference during a predetermined interval.

66. The interruption-free hand-held positioning method, as recited in claim 63, wherein the step (c.2) further comprises the steps of:

(c.2.1) transforming said measured velocity expressed in a body frame into a navigation frame;

(c.2.2) comparing said measured velocity with an IMU velocity to form a velocity difference; and

(c.2.3) integrating said velocity difference during a predetermined interval.

67. The interruption-free hand-held positioning method, as recited in claim 56, wherein the step (b) further comprises an additional step of diffentially deducing said GPS positioning data through a data link.

68. The interruption-free hand-held positioning method, as recited in claim 62, wherein the step (b) further comprises an additional step of diffentially deducing said GPS positioning data through a data link.

69. The interruption-free hand-held positioning method, as recited in claim 63, wherein the step (b) further comprises an additional step of diffentially deducing said GPS positioning data through a data link.