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Sensing and Actuation for Polar Mobile Robot

Sensing and Actuation for Polar Mobile Robot. Eric L. Akers, Hans P. Harmon, Richard S. Stansbury (Presenter), and Arvin Agah ITTC, University of Kansas September 20, 2004. Overview. Introduction Mobile Platform Virtual Prototyping Software Computing and Connectivity Sensors

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Sensing and Actuation for Polar Mobile Robot

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  1. Sensing and Actuation for Polar Mobile Robot Eric L. Akers, Hans P. Harmon, Richard S. Stansbury (Presenter), and Arvin Agah ITTC, University of Kansas September 20, 2004

  2. Overview • Introduction • Mobile Platform • Virtual Prototyping • Software • Computing and Connectivity • Sensors • Actuation • Evaluation

  3. Introduction • Polar Radar for Ice Sheet Measurement (PRISM) • Measurement of ice sheet properties in polar environments • Mobile robot to aid data collection • Transports radar equipment • Tows antenna array • Precise movement for data collection • Environmental challenges: • cold temperatures, harsh winds, blowing snow.

  4. Mobile Platform • Requirements: • Operation at -30 degrees C to 40 degrees C. • Operate at altitudes from 0m to 3000m above sea level. • Transport 300kg of equipment. • Support 40U’s of rack-mount space. • Max ATV Buffalo • Six-wheeled ATV with optional tracks • Amphibious (sealed) • Protective enclosure designed and constructed • Tank-like skid steering.

  5. Mobile Platform – Max ATV Buffalo

  6. Virtual Prototyping • MSC.visualNastran • 3D simulation package. • Evaluation of design parameters and rover performance: • Payload placement • Wheels vs. Tracks • Turning radius. • Maximum climbable slope.

  7. Virtual Prototyping Virtual Prototype of PRISM Rover

  8. Software: • JAVA: • Portability. • Object oriented design. • PRISM Robot API • Interfaces for robot components. • Events and Event Listeners • Forward data updates. • Propagate error notification • Sensor and actuator drivers: • Instantiate API defined components. • Utilizes manufacturers’ proprietary communication languages.

  9. Computing and Connectivity • RS-232 to USB Hub • Supports up to 16 sensors and Actuators • 16-Port Switch • Connects onboard computers • GoBook Max Ruggedized Laptop • Pentium III 750 MHz running Windows XP • Operates at -30 degrees C. • Shock-mounted hard drives. • Waterproof

  10. Sensors Requirements • Task: • Centimeter-level position accuracy. • Video for remote operation and outreach. • Environmental: • Survive in polar environment. • Determine weather conditions • Detect and avoid human-made and naturally-occurring obstacles • Proprioception • Current state: heading, position, orientation. • Internal temperature • Fuel level

  11. Sensor Suite • Global Positioning: • Topcon’s Legacy-E RTK GPS System • Obstacle Detection: • SICK LMS221 Laser Range Finder • Tilt and Temperature: • PNI Corp. TCM2-50

  12. Sensor Suite • Heading: • BEI Systron-Donner MotionPak II Gyroscope • Weather: • Rainwise WS-2000 Weather Station • Vision: • Pelco Esprit pan/tilt/zoom camera

  13. Sensors – Hardware Integration External Sensors

  14. Sensors - Hardware Integration Internal Sensors

  15. Actuation: • Three components to control: • Left and right brake. • Throttle • Linear actuators: • Electromagnetic motors. • No gears. • 20 μm resolution • Controlled by microcontroller with RS-232 interface

  16. Evaluation: • Field experimentation: • Greenland 2003 – North GRIP Camp • Individual sensor tests and data collection • Greenland 2004 – Summit Camp • Integrated tests with radar system. • Climate Survivability: • Sensors operated in polar environment. • Rover would become stuck occasionally when turning in soft snow. • Batteries drained quickly and were replaced with power supplies.

  17. Evaluation • GPS Relative Accuracy: • Measured distance between two points vs. known distance • Relative Accuracy: x = 0.006 ± 0.004 meters y = 0.010 ± 0.007 meters z = 0.022 ± 0.016 meters

  18. Evaluation • GPS Visibility: • Measured number of GPS and GLONASS satellites available at the North Grip camp for a 24-hour period.

  19. Evaluation Obstacle Image vs. LMS221 Image: Snowmobile

  20. Evaluation Obstacle Image vs. LMS221 Image: Sastrugi

  21. Evaluation • Waypoint Navigation • Demonstrates the integration of sensors, actuation, and platform. • Waypoints assigned in a pattern similar to its data collection pattern on the ice. • Thresholds • Waypoint arrival: 1 meter • Heading on target: 10 degrees

  22. Evaluation

  23. Future Work: • Additional fault tolerance. • Tighten waypoint path for greater accuracy. • Reduce rover payload to improve performance in soft snow. • Additional field experiments in Greenland and Antarctica.

  24. Conclusion • Mobile robot constructed for collection of radar data in polar regions. • Robust suite of sensors was selected. • Vehicle automation has been developed and verified using waypoint navigation.

  25. Acknowledgements • This work was supported by the National Science Foundation (grant #OPP-0122520), the National Aeronautics and Space Administration (grants #NAG5-12659 and NAG5-12980), the Kansas Technology Enterprise Corporation, and the University of Kansas.

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