28-05-2014, 11:44 AM
The Georgia Tech Unmanned Aerial Research Vehicle: GTMax
The Georgia Tech Unmanned.pdf (Size: 483.54 KB / Downloads: 26)
ABSTRACT
This paper describes the design, development, and
operation of a research Unmanned Aerial Vehicle
(UAV) system that has been developed at the Georgia
Institute of Technology, called the GTMax. This
description will include the processes put in place to
enable the system to be used for UAV-technology
research, including effective flight testing. Research
UAVs are characterized by the need for continual
checkout of experimental software and hardware. Also,
flight-testing can be further leveraged by
complementing research results with flight-test
validated simulation results for the same experimental
UAV platform. The chosen helicopter-based UAV
platform (a Yamaha R-Max) is well instrumented,
including: differential GPS, inertial measurement unit,
sonar altimeter, radar altimeter, and a 3-axis
magnetometer. One or two flight processors can be
utilized.
INTRODUCTION
This paper presents the development of an open
system Unmanned Aerial Vehicle (UAV) testbed at the
Georgia Institute of Technology and its use in the
DARPA Software Enabled Control (SEC) Program.
The School of Aerospace Engineering at the Georgia
Institute of Technology has been involved in Vertical
Takeoff and Landing (VTOL) Unmanned Aerial
Vehicle (UAV) technology development for more than
ten years. This experience has included initiation of the
Association for Unmanned Vehicle Systems,
International (AUVSI) International Aerial Robotics
Competition and winning it in 1993 with the first
demonstration of autonomous flight of an unmanned
helicopter, including takeoff and landing, at the
contest1. This was followed by the U.S. Army
Autonomous Scout Rotorcraft Testbed (ASRT) project
from 1994 to 1997.
GTMax UAV
The GTMax utilizes the Yamaha R-Max industrial
helicopter airframe, which has the following
characteristics:
• Rotor Diameter: 10.2 ft, Length: 11.9 ft
(including rotor)
• Gross Weight: 205 lb, Payload: >66 lb
• Gasoline, 2 Cylinder, Water Cooled, 246cc
displacement, 21 hp
• Endurance of approximately 60 min (hover)
• Generator and Battery, 12V
• Electric Starter
The hardware components that make up the basic
flight avionics include general purpose processing
capabilities and sensing, and add approximately 35 lbs
to the basic airframe, depending on configuration. The
interface to the helicopter is via a modified Yamaha
Attitude Control System (YACS) interface that allows
raw servo commands to be given without modification
by the stability augmentation.
Data Communication
Generic and highly capable data communication
software has been developed to support a large number
of potential flight and simulator test configurations.
First, these routines supports serial data reading and
writing as necessary for the Commercial Off The Shelf
(COTS) sensors and other custom components used.
Aerial Robotics Competition
In August 2002, the GTMax system was used to
compete in the AUVSI International Aerial Robotics
Competition. For this competition, a UAV system must
automatically locate a specific building in a prescribed
search area, and then identify an opening into the
building. This must be done without any human
assistance during a mission attempt. A camera and
frame grabber were added the basic GTMax, and the 2nd
computer was configured as a image processing
subsystem running the Linux operating system and
utilizing the OpenCV library. Mapping and flight
planning software components were added to the
primary flight computer.
CONCLUSIONS
The extensive use of a variety of simulation
configurations has been of considerable benefit for the
recent development and operation of the GTMax UAV,
and for its use in research and the International Aerial
Robotics Competition. The key features of a flexible
data communication system, models for all hardware
components, and a simulation software infrastructure
enable these configurations. The benefits have included
increased safety, effective participation of a large
number of researchers, the detection of errors before
flight testing, and the effective use of flight test data.