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 requires dangerous sling-load attachment maneuvers Cargo must often be delivered to high risk areas, endangering the crew HOWEVER Helicopter cargo transport using allows delivery of payload to otherwise unreachable areas Pictures source: UAVs CAN FIX THIS!

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:

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

Concept of Operations SR-100 is capable of Autonomous takeoff. 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. When criteria are met for proximity to the target, the hook is servoed through the target loop. 1 Takeoff 2 GPS Waypoint Navigation 3 Track Cargo 4 Hook Cargo

Concept of Operations 5 Increase Altitude 6 GPS Waypoint Navigation Unhook Cargo 7 The cargo will be set on the ground and the hook retracted. The cargo will then be lifted off the ground. GPS navigation will occur again.

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 Control Computer Manipulator PTU Target Fiducials Camera IR Filter Camera PTU Manipulator Batteries

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

Testing

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: