HARDWARE-IN-THE-LOOPTEST RIG FOR

NEAR-EARTH AERIAL ROBOTICS

Vefa Narli, Paul Y. OhDrexel Autonomous Systems Lab (DASL)

Mechanical Engineering and Mechanics, Drexel University

2006 ASME International Design Engineering Technical Conferences

Mission Environments

Robots to handle dirty, dangerous and dull missions

• ClutteredCluttered• Low visibilityLow visibility

– SmokeSmoke– DustDust– Weather conditionsWeather conditions

Notional Mission

• Identify a building

• Identify features

• Hover

• Slow motion

• Bushes, wires, poles, etc.

Notional Vehicle

Cluttered and potentionally dangerous area

Implementation?

Autonomy?

Sensor Suite:Cluttered environ.Weather cond.

Current approach:Ad-hoc with manycrashes andband-aid fixes

Gap: No Sensor metrics to design analytically

“A MAV that flies like an airplane and hovers like a helicopter”, William E. Green, Paul Y. Oh, IEEE/ASME July 2005

Hardware-in-the-Loop (HITL)

HITL:

• Real time

• Real hardware that is being designed

• Math model of the other parts of the system

Literature:

• Test Bed to design insect inspired robotic control, (Reiser)

• Whirling Arm Test Bed to follow terrain, (Netter)

Widely accepted T&E Approach

HITL for Aerial Robots

• XYZ Gantry (6-dof)

• Mockup of the air vehicle

• Real sensors

• Real time

• Real world obstacles

• Sensor data to the math model

Test rig emulates the motion of the real vehicle

Realization: Systems Integrated Sensor Test Rig (SISTR)

• 2300 ft3

• 0.1-3000lux

• NI 7831-R FPGA

• NI 6259 mDAQ

• Model Reference Adaptive Control

Sponsor: NSF CAREER Grant #: 0347430

Real time, near-Earth missions (e.g. Hover-and-stare)

Model Reference Adaptive Control(MRAC)

• Adaptive control used to tune gains • Error = 0, plant (gantry) emulates model (aircraft)

Capable of near-hover speeds with decoupled eqns of motion

Sanity Check: Pendulum

HITL Tests

• Sensor Modeling

• Sensor Suite Design

• Collision Avoidance Tests

• DUST: 0-2.02 x 10-4 lbs/ft3

(Army Reg 70-38 Sec 2-8f(1): fine sand 1.32 x 10-4 lbs/ft3)• RAIN: (0.01 to 0.2 in/min)(Army Reg 70-38 Sec 2-8a 0.03 in/min flow rate)Sheet of rain: 8 ft W X 2ft D X 10 ft H

Filling the gap: Collected sensor metrics in varying lighting, rain, fog

HITL Tests

Baseline Sensor Modeling

• Plywood Obstacle

Baseline tests to show the sensor modeling capability of the test rig

• Cinder Block Obstacle

• Real world obstacles that an aerial robot would encounter• 800 data per distance • 3 in increments (9 in-30 in)

Test Case Example: IR Sensor

• Gaussian

• Can increase sensor accuracy by increasing the number of measurements

• Material/color affects the sensor response

1D Collision Avoidance

Conclusions

No sensor metrics in near-Earth environments

Sensor suite design is crucial for autonomous flight

Current collision avoidance systems are not based on analytical design

Contributions

Hardware-in-the-loop test rig

Lidar, optic flow, ultrasonic, and infrared sensor tests

with real world obstacles such as trees, walls made of cinder block and plywood, poles, and cables

with controlled lighting, rain flow rate, fog and dust density conditions

FUTURE WORK

• Incorporate aircraft dynamics for dynamic tests, and collision avoidance tests

• More sensor tests with different environments, and sensors

• Sensor suite design

• Autonomous aerial transport

Acknowledgements