The antenna stabilization system has been implemented and it provides the ability of continuously pointing the antenna LOS at the desired inertial position.
The stabilizer is an azimuth carrying an elevation antenna gimbal servomechanism. For antenna tracking of a target in angle employs the servo system that utilizes the angle-error signals to maintain the pointing of the antenna in the direction of the target regardless of aircraft motion.
In the thesis, algorithm used for LOS control generates antenna gimbal commands. The antenna motion control is a closed feedback control. With the gimbal commands input to each axis motor, the encoder feed the output signals of motor back to the antenna motion controller and controller will do the PID control. To get better response, Ziegler-Nichols tuning method is taken as the reference of tuning PID parameters. The LOS tracking error is derived from encoders to analyze the system performance in the experiment.
HMI with several operation modes is also developed. The design of HMI becomes simple and extensible by Microsoft Victual C++. By integrating the inertial navigation, inertial measurement and recommending antenna gimbals tie in with the motion cleverly to operate the motion compensation, the stabilization automatically to avoid miss-pointing of the target. The antenna is said to be locked onto the target if the target return is continuously that accepts the commands from the controller and interfaces with the hardware. When the antenna gimbal shelf which simulated aircraft is rotated, the gimbal mechanism will rotate in an opposite direction to compensate.
In future, we can adopt different control methods more than PID to increase
the system performance further. The antenna stabilization system can be putted on the Steward platform with six degrees of freedom. Steward platform motion will affect the orientation of the antenna gimbal to simulate the real state of airborne radar system working on the aircraft.
Reference
[1] Byron Edde, Radar Principle, Technology, Applications, Prentice-Hall International 2nd Editions, 1993
[2] Philippe Lacomme, Jean-Philippe Hardange, Jean-Claude Marchais, Eric Normant, Air and Spaceborne Radar Systems : An Introduction, IEE, Norwich/New York, 2001
[3] George W. Stimson, Introduction to Airborne Radar, Second Edition, Scitech, New Jersey, 1998
[4] Dennis J. Kozakoff, Analysis of Radome-enclosed Antennas, Artech House, Boston/London, 1997
[5]Bogler, Philip L., Radar Principles with Applications to Tracking Systems, John Wiley & Sons, New York, 1989
[6]Daniel Levine, Radargrammetry, Mcgraw-Hill, New York/Toronto/London, 1960
[7] George Biernson, Optimal Radar Tracking Systems, John Wiley & Sons, New York/Hhichester /Brisbane/Toronto/Singapore, 1990
[8] Richard P. Paul, Robot Manipulators: Mathematics, Programming, and Control, MIY Press, 1981
[9] John J. Craig, Introduction to Robotics Mechanics & Control, Addison-Wesley Publishing Company, 1988
[10] Franklin G.F., Powell J.D., Abbas E.N., Feedback Control of Dynamic Systems, Fourth Edition, Prentice-Hall, 2002
[11] 楊憲束，自動飛行控制原理與實務，台北市，全華，民國 91 年 [12] Held K.J., Robinson B.H., “TIER II Plus airborne EO sensor LOS control
and image geolocation”, IEEE Aerospace Conference Proceedings, Vol.2, pp.377-405, 1-8 Feb. 1997
[13] Tsuno, k., Grun, A., Zhang, L., Murai, S. , Shibasaki, R., “Starimager – a new airborne three-line scanner for large scale applications”, Proceedings of ISPRS congress 2004, Istanbul, July 2004, digitally available on CD, 6 pages
[14] 何建興，「多目標追蹤雷達控制器」，國立交通大學，碩士論文，民國
90 年
[15] 楊嘉豐，「機載合成孔徑雷達訊號之運動補償」，國立交通大學，碩士
論文，民國 93 年
[16] 王唯任，「液壓雷達穩定平台之設計、分析與控制」，國立清華大學，
碩士論文，民國 90 年
[17] 黃湫鑌，「空用攝影偵照設備之減震定位平台」，國立清華大學，碩士
論文，民國 90 年
Figures
Figure 2.1 Antenna LOS
(b) With stabilizer (a) Without stabilizer
Figure 2.2 The stabilizer’s effect on image quality
ZA
Figure 2.4 Rotational mapping XA
Figure 2.3 Translational mapping
Figure 2.5 Wide Area Search mode
Figure 2.6 Geometry of Wide Area Search mode
Figure 2.7 Spotlight mode
Figure 2.8 Stripmap mode
Figure 2.9 Coordinate frames for command generation
Figure 2.10 Inertial rate generator transfer partitioning mechanism
Figure 2.11 Geometry between antenna and target
Figure 2.12 Antenna LOS in AC frame
Figure 3.1 The flowchart of airborne radar reconnaissance system
(c) Controp - HRN-2 (b) Optical Alchemy
(a) IAI
- KJ-600 - MOSP
Figure 3.2 Present airborne stabilizer products
Figure 3.3 The SmartMotor 2315D
Figure 3.4 Earth’s coordinate system
Figure 3.5 The gyroscope 3DM-G and its local coordinate
AZ
EL
Figure 3.6 End view of gimbal mechanism
Figure 3.7 Front view of gimbal mechanism
Figure 3.8 SolidWork sketch of gimbal mechanism
Figure 3.9 Actual picture of gimbal mechanism
Figure 3.10 System architecture
Figure 3.11 The integrating assembly circuit diagram
Figure 3.12 Photointerrupter circuit diagram
2 4
Figure 3.13 The Antenna stabilization HMI
3 1
Figure 3.14 Actual picture of antenna stabilization system
Figure 4.2 PID controller block diagram Figure 4.1 System block diagram
(a) AZ axis motor
(b) EL axis motor
Figure 4.3 Step response of each motor
Figure 4.4 Euler angles of aircraft motion (5 Hz)
Figure 4.5 AZ axis input and output (5 Hz)
Figure 4.6 EL axis input and output (5 Hz)
Figure 4.7 Function plot of LOS in the inertial coordinate (5 Hz)
Figure 4.8 Function plot of tracking error (5 Hz)
Figure 4.9 Euler angles of aircraft motion (random motion)
Figure 4.10 AZ axis input and output (random motion)
Figure 4.11 EL axis input and output (random motion)
Figure 4.12 Function plot of LOS in the inertial coordinate (random motion)
Figure 4.13 Function plot of tracking error (random motion)
Tables
Table 4.1 Ziegler-Nichols tuning of PID regulators