Gyre 2: Evaluation of Control Techniques for Autonomous Free-Floating Robots
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Transcript of Gyre 2: Evaluation of Control Techniques for Autonomous Free-Floating Robots
Gyre 2: Evaluation of Control Techniques for Autonomous
Free-Floating RobotsJanuary 20, 2007
Seattle Robotics Society
D. Bliss, A. Lacenski, M. Dockrey
Goals
• Followup to GYRE 1, which established the best image processing algorithm, but did not demonstrate closed-loop control
• Evaluated four control algorithms: naïve hysteresis, proportional, PI, and PID
• Tested aboard NASA’s new C-9 microgravity aircraft in August 2006.
History
• Formed in 2001• Accepted in 2002, postponed flight due to
hardware and documentation issues• GYRE 1 accepted and flew in 2003• Not accepted in 2004• Accepted in 2005, but program postponed due to
aircraft issues• Flew in 2006• DONE!
About the GYRE platform
• 50lbs, 14” cube (NASA requirements)
• Free floats within aircraft
• 3 onboard computers
• National Instruments FieldPoint interface
• 12 cold gas thrusters using air
• 3 orthogonal cameras
• Lithium-polymer batteries
Onboard Computers
• Comell Taiwan LV-671M single-board computers, mini-ITX
• Intel Pentium-M 1.6, ~2 GIPS, 128MB RAM, 1GB CompactFlash
• Cardbus Firewire interface for high-speed video• Mini-PCI 802.11b with external antennas• Onboard 100mbps Ethernet• Serial interface to NI FieldPoint
National Instruments FieldPoint
• A general-purpose industrial interface system
• One network module, up to 64 I/O modules
• Using FP-PG-522 pulse generator modules
• Allows all hard realtime to be done in FieldPoint, no need for realtime OS on SBCs
Cold Gas Thruster System
– Two 1.8L tanks at 4500 psi– Regulators on each tank reduce to 200 psi (100
psi for 2006 flights)– Low-side air manifolded and distributed to
twelve high-speed control valves with attached custom CNC-machined thrusters
– Minimum thrust bit 30 msec, about 0.06 N-S– Continuous thrust about 2N
Onboard Cameras
• Firewire
• TI chipset
• 640x480x30fps
• Custom CNC-machined enclosures
• Image recognition, feature extraction, motion vector extraction, and compensation done by onboard SBCs, one per camera
Lithium-Polymer Batteries
• The first rule of LiPo batteries:– DON’T USE LIPO BATTERIES
• 28V, ~3AH, ~45m runtime
• Horror stories
• But, great power density!
Onboard operation
• Control laptop
• Canon GL2 video camera for data collection
• Two operators
Results
Algorithm Average result Number of trials
Hysteresis 2 6
Proportional 1.57 15
Proportional-Integral 3 1
Proportional-Integral-
Derivative
3.333 3
Questions?
• David Bliss
• http://depts.washington.edu/gyre