airborne attitude determination and ground target location using gps information and vision...
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Airborne Attitude Determination and Ground
Target Location Using GPS Information and
Vision Technique
Shan-Chih Hsieh, Luke K.Wang, Yean-Nong Yang†,Fei-Bin Hsaio*, Fan-Jen Tsai
Dept. of Electrical Engineering,National Kaohsiung University of Applied Sciences†Dept. of Electronic Engineering, National I-Lan Institute of Technology
*Institute of Aeronautics and Astronautics, National Cheng Kung University
1.INTRODUCTION
•Sensor fusion method(vision+GPS+INS,or gyros)
•Vision-based navigation
•Focus of expansion(FOE)
•Attitude determination
GPS
Wabba problem
Least-squares
•Rotation representation
2.1The Homogeneous Transformation
CZCYCX
CTb
bTe
Z
Y
X
{b}:body coordinate
{e}:ECEF
{C}:camera coordinate
{C} -----> {e}
(2.1-1)
10000
0
0
Z
YeRb
X
eTb
For our case,
(2.1-2)
bRe: attitude of aircraft with respect to {e}
[X0 Y0 Z0]T :origin of the body frame.
2.2The Kinematic Equation
Quaternion: q = [q0 q1 q2 q3 ]T
Kinematics: qq
2
1(2.2-1)
0
0
0
0
123
132
231
321
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q <--->R(q)
.
)(2)(2
)(2)(2
)(2)(2
)(2
3
2
2
2
1
2
010322031
1032
2
3
2
2
2
1
2
03021
20313021
2
3
2
2
2
1
2
0
qqqqqqqqqqqq
qqqqqqqqqqqq
qqqqqqqqqqqq
qR
{b}
GPS antenna
{C}
Earth
Target
{e}
Figure 1.The illustration of the imaging geometry and target location
3.THE GPS-VISION SYSTEMSystem: (1)a GPS pseudorange receiver
(2)a CCD camera
3.1The Monocular Vision System
Perspective projection:C
C
Z
Xfi 0
C
C
Z
Yfj 0
3.2The Kalman Filter Formulation
kkk dxfx )(1
kkk vxhZ )(
whereTT
kPosT
kqT
kw
kx
1011111
State:
Linearization:kkkk dxFx 1
kkkk vxHZ
where.
33430330
340
123
132
231
321
22
33043033
11
11
012
103
230
321
I
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I
x
f(x)F
qqq
qqq
qqq
qqq
232231
131231
0 0
0)(TT
TT
HH
HHf
x
xhH
3.3The Problem Formulation for Identification of Target Location
Q:Given (1)a sequence of noisy measurement of ground target (2)a sequence of time-tagged GPS measurement of aircraft
body coordinate
Solve:(1)WGS-84 coordinate of ground target
(2)aircraft’s attitude
4.SIMULATION
Aircraft maneuver:
pitch rate=0.001 grad.
Translate with constant velocity
measurement noise covariance: diag[10 m2 0.01 pixel2]
Ground target:stationary with an unknown WGS-84 coordinate
5.SUMMARY
Key features:
•Using only a single GPS pseudorange receiver to compute attitude
•Simultaneous determination of both ground target location and aircraft’s attitude
•Using EKF
Future Work
•Using Unscented Kalman Filter
•Using Particle Filter
•Using sophisticated camera model instead of pinhole model