Unmanned Aircraft Systems for Radio Echo Sounding

Outline

• CReSIS Platforms Overview• Meridian UAS Status Update (Medium UASs)• 40% Yak UAS Status Update (Small UASs)• Sensor Platform Integration (Other UASs)• Future Developments, Plans and Challenges

What do the >700 Available UAV Platforms Offer?

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Design Space

Number Manufacturer Designation1 Aerosonde MK32 Meteor Mirach 263 Aurora Perseus B4 General Atomics Predator5 IAI Heron6 General Atomics Gnat 7507 Aerospatiale Sarohale8 Northrop Grumman Global Hawk9 Kawada Robocopter10 Aurora Theseus11 DeHavilland Twin Otter12 Lockheed P-3 Orion13 Lockheed C130

KU Unmanned Aircraft

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Sensors – UAS-Based Radar•Design Evolution is ongoingEight transmit/receive channels

digital beamsteering and interferometryEight data acquisition channels

12-bits, 111-MHz sampling rateVolume: 50 x 50 x 20 cmMass: 55 kgInput power: 400 WSmall form factor for RF modules

Custom antenna elements 3.2-lb Vivaldi antenna (51 x 40 x 0.32 cm)162 to 1121 MHz

195-MHz center frequency30-MHz bandwidth

scaled down 2-channel version is developed for UAS field tests

Meridian UAS Overview

Parameter Units ValueWeights

Takeoff Weight lbs 1,100Empty Weight lbs 791Payload Weight lbs 165Fuel Weight lbs 120

PerformanceCruise Speed kts 130Range nm 950Endurance hrs 12L/DCr ~ 13.9

PowerplantEngine ~ TAE Centurion 2.0Power hp 135

For more information, contact:Rick Hale, PhD, Associate Professor, Aerospace Engineering1530 W 15th St., 2120 Learned Hall, Lawrence, KS 66045785-864-2949, rhale@ku.edu, www.cresis.ku.edu

Multi-Mission Science-Driven Payload Options

Optical/Infrared Camera RADAR Antennas

Magnetometer

Aerosol Detection

Meridian UAS range and endurance improve with reduced cruise, reduced payload weight

or higher altitude missions

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Full Radar Suite, 2008

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Aerosonde MK3

Cruise Speed = 100 kts (180 km/hr)

Meridian UAS Flight Test History: Configurations and Fields

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August 28th, 2009

September 10th-15th, 2009

December 31st, 2009

July 17 – August 12, 2011;December 20, 2011

Meridian UAS System Improvements• Installation of Thielert Centurion 2.0 engine, and

removal of ground cart• Lower weight cowling (12 lbs)• Redundant 2.4GHz receivers, with frequency

hopping for lower risk of interference or jamming• Improved avionics package and starting sequence • Improved safety features (external power, tethered

engine kill)• Common avionics on 40% Yak enables more

frequent training• Flight tests for assisted landing modes• First COA application in review to enable training and

operation in National Airspace

Depth Sounder (MCoRDS) Progress

Hardware Updates• 4-Channel RF Receiver in a 3U

PXI Form Factor.– Reduced Size.– Easy Integration into Digital System.– Adapted to Other Systems.

• 1kW T/R Module.– Power Amplifier and Duplexer Tested

and Thermal Images at 1kW Operation.

– Improve System Sensitivity.

40% Yak “Trainer” Is Also Being Equipped with Dual Low Frequency Sounder

Local flights imminent; potential Alaska mission in August pending COA; Antarctic deployment December 2013; Greenland deployment March 2014

Dual Low Frequency Sounder• Miniaturized system for small UAS operation.

– 14 and 35 MHz.– 100-200 W Tx Power.– 10 lbs.

• Antennas integrated into the UAS structure.• 2-D Aperture Synthesis.• Sub systems applicable to other sensors.

– Backpack portable.– Snow/Ku-Band Systems.

100-Watts Pulsed Amplifier (230 gr.)(image from SpinCore Inc).

Compact Digital System.• Prototype Version.• Embedded Microblaze Processing Core for

command, control, data acq. & storage.• Mixed Signal Front End (ADC/DAC/Clock).• Single Chip RF Receiver (LNA/VGA/LPF).• SD-Card Storage (128 GB, ~2MB/sec).• Integrated GPS receiver.• Future hardware teaching platform

(DSP/FPGA).

Snow Radar Results

Comparison of Snow Radar with AMSR-E derived snow depth.

Interface Tracking: Snow Thickness and Accumulation Rates.

Satellite can be used to estimate sea ice thickness from freeboard measurements.• Significant error can arise from unknown snow

loading.• Laser will overestimate thickness.• Radar is more complicated because the

reflecting surface depends on snow conditions.Snow cover modulates heat transfer between the atmosphere and the ocean.

Weddell Sea

Ikhana/Sierra Snow Radar• Miniaturized version of the snow

radar for UAS deployments.– Compact COTS Controller & DAQ.– Custom wideband chirping PLL.– Autonomous Operation.

• Originally targeted for NASA Ikhana platform with modifications for Sierra.

Ikhana

http://www.nasa.gov/centers/dryden/news/FactSheets/FS-097-DFRC.html

Mizoplex/Ikhana/Sierra• Useful Payload: 100 lbs• Max Altitude: 12,000 ft• Air Speed: 60 knots

• Range: 600 Nmi• Endurance: 10 hours• Power: 19Amps @ 28

V DC

Sea Ice Flight Tests, Alaska, July/August 2013

Precision Formation Flight Requires Coordinated Sensor and Platform

Development

Improved Command and Control: Advanced Nonlinear Controller for UAS

Experience gained from the 2011 campaign has helped to define new priorities in the control and command side research. Over-the-horizon flights and CReSIS missions in hostile polar regions demand adaptive and resilient controllers. To meet safety and performance requirements in unstructured environment (e.g. Polar Regions), a new nonlinear model predictive controller and an adaptive guidance logic are designed for CReSIS UASs .

Performance of new Meridian’s NMPC Trajectory Following:Controller in Presence of Cross-Wind Adaptation of Controller to a 20% Intentional Reduction 3D Flight Views

of CL0 (e.g. damage or impairment)

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GlobalHawk/Ventures

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EMI Testing and Mitigation• CReSIS radars are capable of

detecting signals on the order of nanovolts

• EMI can dramatically degrade radar performance and interfere with UAS operation and control

• We have taken a proactive attitude toward EMI and EMC issues

– Purchased a 4x8 meter chamber– Conducted tests at the Sprint chamber– Submitted MRI proposal to develop a

10-meter chamber at CReSIS/KU• Example: reduction of a 150 MHz

source radiating from a compact PCI power supply

CReSIS Anechoic Chamber FacilityNSF MRI Project

• The Chamber has become an extremely useful and valuable asset for Radar/Avionics/System design and testing. – EMI identification and reduction.– Improve sensor sensitivity.– Reduce interference between sensors

and avionics.– Test systems at full power.– Measure antenna gain and efficiency.– Measure array patterns and mutual

coupling.– Industry collaborations.– Student Education.– Fully functional in Summer 2012.– chamber.ku.edu

Sensor Noise Reduction

Platform and sensor interference mitigation.

Antenna Pattern and Coupling

Anechoic Chamber Use• P-3 MCoRDS Array Analysis.

– Identified differences in element radiation patterns.

– Need to characterize to correctly reduce surface clutter.

• Radar Electronics Noise Analysis.– Routine measurements of all new equipment

and upgrades to characterize noise.• HF Sounder.

– Antenna Pattern & Efficiency.• Reduction in Antenna Performance due to

proximity of servo wires.– Interference from Avionics.

• Increased noise floor due to servo control transients.

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Sensor Platform Integration

Simulated and experimental data confirms compensation techniques for wing flexure induced pattern rotation and shifting and filling of nulls; more important with small flexible airframes typical in UAS

Summary and Plans• Continued emphasis on ground and flight

tests and sensor integration for upcoming deployments– Dual low frequency sounder on Yak G1X– UAS radar on Meridian– UWB radar on Basler

• Continued support of other external platform integration

• Pursue new opportunities