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Proceedings Paper

High-performance two-axis gimbal system for free space laser communications onboard unmanned aircraft systems
Author(s): Michael Locke; Mariusz Czarnomski; Ashraf Qadir; Brock Setness; Nicolai Baer; Jennifer Meyer; William H. Semke
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Paper Abstract

A custom designed and manufactured gimbal with a wide field-of-view and fast response time is developed. This enhanced custom design is a 24 volt system with integrated motor controllers and drivers which offers a full 180o fieldof- view in both azimuth and elevation; this provides a more continuous tracking capability as well as increased velocities of up to 479° per second. The addition of active high-frequency vibration control, to complement the passive vibration isolation system, is also in development. The ultimate goal of this research is to achieve affordable, reliable, and secure air-to-air laser communications between two separate remotely piloted aircraft. As a proof-of-concept, the practical implementation of an air-to-ground laserbased video communications payload system flown by a small Unmanned Aerial Vehicle (UAV) will be demonstrated. A numerical tracking algorithm has been written, tested, and used to aim the airborne laser transmitter at a stationary ground-based receiver with known GPS coordinates; however, further refinement of the tracking capabilities is dependent on an improved gimbal design for precision pointing of the airborne laser transmitter. The current gimbal pointing system is a two-axis, commercial-off-the-shelf component, which is limited in both range and velocity. The current design is capable of 360o of pan and 78o of tilt at a velocity of 60o per second. The control algorithm used for aiming the gimbal is executed on a PC-104 format embedded computer onboard the payload to accurately track a stationary ground-based receiver. This algorithm autonomously calculates a line-of-sight vector in real-time by using the UAV autopilot's Differential Global Positioning System (DGPS) which provides latitude, longitude, and altitude and Inertial Measurement Unit (IMU) which provides the roll, pitch, and yaw data, along with the known Global Positioning System (GPS) location of the ground-based photodiode array receiver.

Paper Details

Date Published: 1 March 2011
PDF: 8 pages
Proc. SPIE 7923, Free-Space Laser Communication Technologies XXIII, 79230M (1 March 2011); doi: 10.1117/12.873938
Show Author Affiliations
Michael Locke, The Univ. of North Dakota (United States)
Mariusz Czarnomski, The Univ. of North Dakota (United States)
Ashraf Qadir, The Univ. of North Dakota (United States)
Brock Setness, The Univ. of North Dakota (United States)
Nicolai Baer, The Univ. of North Dakota (United States)
Jennifer Meyer, The Univ. of North Dakota (United States)
William H. Semke, The Univ. of North Dakota (United States)

Published in SPIE Proceedings Vol. 7923:
Free-Space Laser Communication Technologies XXIII
Hamid Hemmati, Editor(s)

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