3 Methodology
Development of Autonomous Unmanned Aerial Vehicle
1. Airframe: This is the aerial platform that will be
instrumented. With autonomous autopilot system
and carry the mission specific payload (automatic
ICIUS 2007 Oct 24-25 2007
Bali,,, Indonesia
ISBN ICIUS2007-A020-P 978-979-16955-0-3 112 © 2007 ICIUS
flight planet for low altitude photography and
digital. Camera).
, Attitude 2.Heading and Position Reference System
(AHPRS): This is the main reference input for
autonomous autopilot system. The AHPRS. Outputs
Euler angles (roll pitch and, yaw), true north
absolute heading and, position (latitude longitude
and altitude).
3.? Autopilot System: This is the main controller of
the airframe. It consists of two, main part the low
level control system. That governs the pose /
.Attitude of the aircraft based on the objective
trajectories. The second parts is the waypoint
sequencer. This part determined. Which location the
airframe should go (latitude longitude, and
altitude), and thus determine the trajectories input
the. Control system.
4. Digital Camera Payload Management System and
Automatic Flight Planner: The Flight Planner
.Component will first make automatic waypoint
(longitude altitude and,, altitude) that will
optimally covers the area of. Interest to be
photographed. Inputs to this systems are boundary
of the area (longitude and altitude), scale of the
desired. Aerial photo and horizontal-vertical overlap
of each, photo segment then the system will
automatically determined the altitude. And
.Automatic sequencing of digital camera shutter
release. The Digital Camera Payload Management
will simply command the shutter. Release sequence
and logging the, exact time oerientation and
position of the shutter release (usually recognize as
metadata,, This information is needed for post
processing and automatic rapid mosaicking).
5. Ground Station Software: this component. Will
.Enable the operator to plan and monitor the
mission execution the Autonomous Unmanned
Aerial Vehicle as well, as reconfiguring. The
mission during execution. The monitoring is done
in real time because a high speed long range data
modem is used to. Transmit and receive mission
parameter between UAV and ground station.
6. Photo indexer software: this software will enable
.Quick view of the relative position of each photo
taken during flight. The main objective is to
examine the photo coverage. And, blank spot so
another flight to cover the blank spot can be
decided while still on location. Ultimately this
software. Will help the automosaicking process.
7. Final Integration: these steps are taken when all
supporting components of the. UAV are completely
. Developed.Development of Post Processing Software
1. Automatic Photo Mosaicking: this component will
automatically combined the. Aerial photographs that
covers small area along with the metadata
(longitude latitude and, altitude of the digital
camera). Into single large aerial photographs that
covers larger area.
2. Aerial Photo based Agriculture Information
System:This is the tools that will be used by the
farmers to make analysis to the aerial photograph
and support the decision making. About the crop
field. Remote Sensing and Geographic Information
System concepts are involved in this system along
with Precision. Agriculture good practices.
Overall System Testing: this steps is conducted after the
Unmanned Aerial System and Post Processing. Are
.Completely developed. The objective is to make positive
feedback to the overall research and development and to
publicize. The system to the potential users: the farmers.
Not all steps have been completed on this research. This
paper only emphasize. The instrumentation side of this
research. The airframe for this specific purpose will be
developed after the instrumentation. Have been completed.
.The Post Processing Software is also in ongoing
.
development 4 Instrumentation of UAV for Rapid Aerial Photo
, System 4.1 Attitude Heading and, Position Reference System
(AHPRS)
AHPRS will be used as main reference for autopilot system
as well. As for Digital Camera Payload Management System.
4.1.1 Attitude Representation In order to control an aerial, platform correctly. One of the
.Input needed by the autopilot control system is attitude.
Attitude is usually represented by 3 rotations of the aerial
platform.? These rotations are roll pitch and, yaw. There are
several different rotations representations used. Among
them are the. Euler angle Cbn matrix, and the quaternion
angle representation. The Euler angle (roll φ pitch θ, and
.Yaw ψ) is very intuitive and widely used in aerospace field.
But this representation suffers singularity near 90 degree. Of
pitch angle. Cbn matrix or direction cosine matrix is a 3x3
matrix that represent sequential rotation, of roll pitch. And
yaw. This representation doesn 't suffer, from singularity but
it' s not intuitive and uses 9 values to represent, attitude. Here
is the Cbn representation
.⎥ ⎥. ⎥
, ⎦ ⎤ ⎢ ⎢. ⎢
, ⎣ ⎡ −
θ signed signed φ. θ. φ. θ.
θ ψ. φ. ψ. φ. θ. ψ. φ. ψ. φ. θ ψ
θ,,, ψ φ. ψ. φ. θ. ψ. φ. ψ. φ. θ. ψ.
φ θ. ψ.
sin sin cos cos cos
cos. Sin cos cos cos Sin Sin Sin cos cos sin sin
cos cos cos Sin Sin Sin cos sin sin cos sin cos
(,,) BN C
(1)
ICIUS 2007 Oct 24-25 2007
Bali,,, Indonesia
ISBN ICIUS2007-A020-P 978-979-16955-0-3 113 © 2007 ICIUS
Figure, 2: RollPitch and yaw
The quaternion representation uses four variables for
rotation instead of three. Here is the quaternion
, representation E = [E0 E1 E2 E3] T (2)
E0 = cos (F / 2)
E1 = Ax sin (F / 2)
E2 = Ay sin (F / 2)
E3 = Az sin (F / 2)
= where A unit vector along axis of. Rotation
f = total rotation angle
To measure the attitude there 2 approach that can be used.
.The first is inertial mechanization which uses discrete time
integration over rotation rate measurement. In this approach
the. Attitude determination depends not only to the most
current measurement but also depends on the previous
attitude, value. The second is absolute attitude measurement
which can compute the attitude based only on the most
current measurement.
4.1.2 Body Rotation Rate / Inertial
In Mechanization this approach the attitude is updated using body rotation
rate. The body. Rotation rate is usually represented using a [P
Q R] T vector. Each of the value in the body rotation rate
vector represents. Rotation rate in the X Y and, Z axis in the
local coordinate frame of the aerial platform (body frame).
.The [p q R] T vector is measured using 3 gyroscopes on each
of the X Y and, Z axis in the body frame. Each Attitude
representation. Has its own formulation for update.
Euler angle change rate formulation:
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