Autonomous Cargo Transport System
for an Unmanned Aerial Vehicle, using
Visual Servoing
Noah Kuntz and Paul Oh
Drexel Autonomous Systems Laboratory
Drexel University, Philadelphia, PA
Motivation
Helicopter cargo transport using allows delivery of payload
to otherwise unreachable areas
UAVs CAN FIX THIS!
HOWEVER
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Helicopter cargo transport requires dangerous sling-load
attachment maneuvers
Cargo must often be delivered to high risk areas,
endangering the crew
Pictures source: http://www.mccoy.army.mil/ReadingRoom/Triad/06112004/Sling-load%20Sinai.htm
Potential Cargo
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Medicine
Specialized parts or tools for in-field repair
UGVs for bomb disposal or surveillance
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Such as the Bombot, a low cost compact bomb
disposal robot manufactured by the West Virginia
High Technology Consortium (WVHTC) Foundation
Left picture source: http://robotgossip.blogspot.com/2006/01/bombot-to-be-built-in-west-virginia.html
Helicopter Cargo Carrying Tests
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Test cargo
wasplatform
a small proves
remote capable
control UGV, for
SR-100
potential UGV/UAV teaming missions
Computer controlled takeoff, flight, and landing
Demonstrated suitability of the SR-100
unmanned helicopter for light cargo transport
Cargo Carrying Methods
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Fixed Cargo Bay
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Actuated
Sling
Load Hook Wins for Unmanned Heli
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CONs – Requires landing, limited cargo size,
decrease in maneuverability
PROs – Cargo is protected and stable
CONs – Oscillation danger, difficult attachment
PROs – Common, allows diverse cargo
Actuated Hook
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CONs – Limits weight of cargo
PROs – Can provide active damping, allows
autonomous attachment
Concept of Operations
1
Takeoff
SR-100 is capable of
Autonomous takeoff.
2
GPS Waypoint
Navigation
Autonomous
hovering and GPS
waypoint navigation
is integral to the SR100’s control
package.
3
Track Cargo
Tracking is
performed with
visual servoing using
onboard camera and
computer.
4
Hook Cargo
When criteria are
met for proximity to
the target, the hook is
servoed through the
target loop.
Concept of Operations
5
Increase Altitude
The cargo will then
be lifted off the
ground.
6
GPS Waypoint
Navigation
GPS navigation will
occur again.
7
Unhook Cargo
The cargo will be set
on the ground and
the hook retracted.
Technical Requirements
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Accurate tracking in all lighting conditions
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Reliable cargo pickup
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Weight within capability of the helicopter
Research Path
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Establish load carrying ability of unmanned helicopter
platform
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Set up hardware-in-the-loop simulation environment for
testing and evaluation
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Develop the cargo pickup system in test environment
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Refine system and retest
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Flight test the system, for verification and validation
Challenges
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Overall “Mobile Manipulation” problem
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Tracking target under variant lighting
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Tracking while helicopter wanders
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Servoing the hook fast enough
Systems Integrated Sensor Test Rig
(SISTR)
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6DOF capable with velocity
control
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Environmental simulation
including lighting control
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Allows recreation of flight
conditions for testing and
evaluation
Sponsored by the National
Science Foundation
SISTR Flight Data Playback
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Recreate helicopter
motion under controlled
condition
SISTR replicates flight movements
Encoder data validates
the gantry velocity
controller
Mechanism Notional
Gantry Arm
Batteries
Control
Computer
Camera
IR Filter
Camera
PTU
Fiducials
Target
Manipulator
PTU
Manipulator
Mechanism
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2DOF stepper motor
camera PTU for high
speed and precision
2DOF hook PTU for
high torque, low cost,
and light weight
Vision
Structured lighting approach
used for initial testing
 Target uses krypton bulbs as
fiducials,
with high
Simple
tracking
forIRlow computation / high speed
emission
 IR band-pass filter removes
non-infrared light
 Threshholding operation
isolates fiducials which are
tracked using image-based
pose regulation
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Controller
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Control Computer
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Mini-ITX single board computer
Solid state drive for vibration resistance
Testing Procedure
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Gantry replays recorded helicopter velocities
Target is placed in each of nine positions within 20 cm
(GPS accuracy) from ideal
Testing
Results
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Near-miss conditions could be eliminated
Success rate of ~83% should be possible with minor
improvements
Closed loop pickup detection will improve
Contributions + Future Work
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Objectives Met
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Accurate tracking in all lighting conditions
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Consistent cargo pickup
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61% - work in progress
Weight within capability of the helicopter
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Tracking demonstrated under most difficult condition
~ 15 lbs, within 20 lb limit
Results will be confirmed with flight tests
Acknowledgements
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National Science Foundation
US Army Telemedicine Advanced
Technology Research Center (TATRC)
Piasecki Aircraft Inc
For more info please see:
http://www.pages.drexel.edu/~nk752/