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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.
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Autonomous Cargo Transport System for an Unmanned Aerial Vehicle, usingVisual 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 • Helicopter cargo transport requires dangerous sling-load attachment maneuvers • Cargo must often be delivered to high risk areas, endangering the crew UAVs CAN FIX THIS! HOWEVER Pictures source: http://www.mccoy.army.mil/ReadingRoom/Triad/06112004/Sling-load%20Sinai.htm
Potential Cargo • Medicine • Specialized parts or tools for in-field repair • UGVs for bomb disposal or surveillance • 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 • Test cargo was a small remote control UGV, for potential UGV/UAV teaming missions • Computer controlled takeoff, flight, and landing • Demonstrated suitability of the SR-100 unmanned helicopter for light cargo transport SR-100 platform proves capable
Cargo Carrying Methods • Fixed Cargo Bay • CONs – Requires landing, limited cargo size, decrease in maneuverability • PROs – Cargo is protected and stable • Sling Load • CONs – Oscillation danger, difficult attachment • PROs – Common, allows diverse cargo • Actuated Hook • CONs – Limits weight of cargo • PROs – Can provide active damping, allows autonomous attachment Actuated Hook Wins for Unmanned Heli
GPS Waypoint Navigation Takeoff Track Cargo Hook Cargo 2 4 1 3 Concept of Operations SR-100 is capable of Autonomous takeoff. When criteria are met for proximity to the target, the hook is servoed through the target loop. Autonomous hovering and GPS waypoint navigation is integral to the SR-100’s control package. Tracking is performed with visual servoing using onboard camera and computer.
Concept of Operations 5 6 7 Increase Altitude GPS Waypoint Navigation Unhook Cargo The cargo will then be lifted off the ground. GPS navigation will occur again. The cargo will be set on the ground and the hook retracted.
Technical Requirements • Accurate tracking in all lighting conditions • Reliable cargo pickup • Weight within capability of the helicopter
Research Path • Establish load carrying ability of unmanned helicopter platform • Set up hardware-in-the-loop simulation environment for testing and evaluation • Develop the cargo pickup system in test environment • Refine system and retest • Flight test the system, for verification and validation
Challenges • Overall “Mobile Manipulation” problem • Tracking target under variant lighting • Tracking while helicopter wanders • Servoing the hook fast enough
Systems Integrated Sensor Test Rig (SISTR) • 6DOF capable with velocity control • Environmental simulation including lighting control • Allows recreation of flight conditions for testing and evaluation Sponsored by the National Science Foundation
SISTR Flight Data Playback • Recreate helicopter motion under controlled condition • Encoder data validates the gantry velocity controller SISTR replicates flight movements
Mechanism Notional Gantry Arm Batteries Control Computer Camera IR Filter Manipulator PTU Camera PTU Fiducials Manipulator Target
Mechanism • 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 IR emission • IR band-pass filter removes non-infrared light • Threshholding operation isolates fiducials which are tracked using image-based pose regulation Simple tracking for low computation / high speed
Controller • Control Computer • Mini-ITX single board computer • Solid state drive for vibration resistance
Testing Procedure Gantry replays recorded helicopter velocities Target is placed in each of nine positions within 20 cm (GPS accuracy) from ideal
Results • 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 • Objectives Met • Accurate tracking in all lighting conditions • Tracking demonstrated under most difficult condition • Consistent cargo pickup • 61% - work in progress • Weight within capability of the helicopter • ~ 15 lbs, within 20 lb limit • Results will be confirmed with flight tests
Acknowledgements • 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/