ATTITUDE CORRECTION APPARATUS AND METHOD FOR INERTIAL NAVIGATION SYSTEM USING CAMERA-TYPE SOLAR SENSOR

• US 20090326816A1
• Filed: 05/01/2007
• Published: 12/31/2009
• Est. Priority Date: 05/30/2006
• Status: Active Grant

• Current Assignee: INHA University
• Original Assignee: INHA University
• Inventors: JANG, SE AH, PARK, CHOON BAE, CHOI, KEE YOUNG
• Granted Patent: US 7,805,244 B2
• Time in Patent Office: Days
• US Class Current: 701/213
• CPC Class Codes: G01C 21/1656 with passive imaging devices, e.g. cameras
• CPC Class Codes: G01S 3/781 Details
• CPC Class Codes: G01S 3/7862 mounted on a moving platform, e.g. space vehicle
• CPC Class Codes: G01S 3/7864 T.V. type tracking systems

Abstract

Disclosed herein is an attitude correction apparatus for an Inertial Navigation System (INS) using a camera-type solar sensor. The present invention relates to a system for correcting errors occurring in an inertial navigation system, in which inertial sensors, such as gyroscopes and accelerometers are combined with each other to calculate the attitude, velocity and position of an airplane, and to an apparatus for utilizing a sun-line of sight vector, generated by a camera-type solar sensor, that uses images of the moving sun, and the output value of the inertial navigation system, thus correcting the attitude of an airplane and the errors of sensors. The attitude correction apparatus of the present invention includes a camera-type solar sensor for detecting the sun, a signal processing unit for receiving and synchronizing information, and a data collection processing unit for performing post-processing on information, thus correcting an error.

Claims

1. An attitude correction apparatus for an inertial navigation system using a camera-type solar sensor, comprising:

a camera-type solar sensor for detecting a sun using a camera in order to measure an attitude of an airplane;

a signal processing unit for receiving attitude and position values from the inertial navigation system and information about a sun-line of sight vector from the camera-type solar sensor, and synchronizing the attitude and position values with the sun-line of sight vector information; and

a data collection processing unit for performing post-processing on information received from the signal processing unit, thus correcting an error.

2. The attitude correction apparatus according to claim 1, wherein the camera-type solar sensor comprises:

the camera;

a camera driving motor unit, on which the camera is mounted, and which is adapted to perform rotational motion; and

an image acquisition processor for acquiring an image required for data processing from the camera, and detecting a position of the sun from the acquired image.

3. The attitude correction apparatus according to claim 2, wherein the camera driving motor unit is implemented using a driving motor having two shafts for tilting and panning to perform three-dimensional motion of the camera.

4. The attitude correction apparatus according to claim 2, wherein the camera driving motor unit comprises:

a panning shaft driving motor;

a panning rotating plate coupled to and rotated along with the panning shaft driving motor;

a panning shaft installed on a center portion of the panning rotating plate;

a tilting shaft driving motor installed on the panning shaft;

first and second tilting shaft driving motor gears coupled to and rotated along with the tilting shaft driving motor;

a tilting shaft installed on the second tilting shaft driving motor gear;

a tilting rotating plate installed on the tilting shaft, and adapted to fixedly install the camera on the tilting rotating plate; and

tilting shaft supports for supporting both ends of the tilting shaft.

5. The attitude correction apparatus according to claim 1, wherein the camera-type solar sensor comprises:

the camera; and

an image acquisition processor for acquiring an image required for data processing from the camera and detecting a position of a sun from the acquired image, and

wherein two or more camera-type solar sensors are installed along a body of the airplane.

6. The attitude correction apparatus according to claim 1, wherein the data correction processing unit receives the values from the inertial navigation system and the solar sensor and thus calculates an estimated error value using a Kalman filter algorithm.

7. The attitude correction apparatus according to claim 5, wherein the data collection processing unit further comprises a Global Positioning System (GPS) in addition to the inertial navigation system and the solar sensor, thus more precisely calculating estimated errors of velocity and position, as well as an estimated error in attitude, using the Kalman filter algorithm.

8. An attitude correction method for an inertial navigation system using a camera-type solar sensor, wherein information about an attitude of an airplane is extracted through comparison of a sun-line of sight vector in a navigation coordinate system with a sun-line of sight vector in a body coordinate system generated by the camera-type solar sensor, and an error in attitude is corrected using the information about the attitude of the airplane.

9. The attitude correction method according to claim 8, wherein a method of correcting the error in attitude comprises the steps of:

(a) a camera capturing an image of a sun through rotation of a camera driving motor unit included in the camera-type solar sensor;

(b) an image acquisition processor receiving the captured image, and thus calculating the sun-line of sight vector in the body coordinate system in consideration of an angle of motion of the camera driving motor unit;

(c) synchronizing the sun-line of sight vector, calculated at step (b), with information about attitude, velocity and position obtained by an inertial navigation system, using a signal synchronization microprocessor of a signal processing unit;

(d) a data collection processor of a data collection processing unit receiving the synchronized information, and estimating an error in attitude using a Kalman filter, which is an algorithm for minimizing a mean square error between an actual value and an estimated value; and

(e) transmitting the estimated error to the inertial navigation system, thus correcting the attitude of the airplane.

10. The attitude correction method according to claim 9, further comprising the step of re-estimating an error in attitude by applying a time difference between a missed time point at which the sun was not captured and a time point at which the sun is captured again, to the Kalman filter algorithm when the camera is temporarily unable to capture the sun, between steps (d) and (e).