ECE5320 Mechatronics Assignment#01: Literature Survey Actuators Topic: Torque Coils/Rods and Reaction WheelsOutlineReference listTo explore furtherOperational InterfaceAttitude ControlSlide 7Major ApplicationReactions WheelsReaction WheelsReaction Wheels in SpaceLocation of Reaction WheelsTorque Coils vs. RodsTorque RodsTorque Rods in SpaceTorque CoilsSlide 17Torque Coil ControllerTorque ControllerPlaces to buy/CostECE5320 MechatronicsAssignment#01: Literature Survey Actuators Assignment#01: Literature Survey Actuators Topic: Torque Coils/Rods and Reaction WheelsPrepared by:Brandon ThurgoodDept. of Electrical and Computer Engineering Utah State UniversityE: [email protected] ; T: (435)797-7577; F: (435)797-3054 (ECE Dept.)3/10/200601/13/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-2Outline –Reference list–To explore further–Operational interface–Attitude Control–Major Application–Reaction Wheels–Torque Rods–Torque Coils–Buy/Cost01/13/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-3Reference list•http://einstein.stanford.edu/highlights/hl_102805.html•http://www.sti.nasa.gov/tto/spinoff1997/t3.html•http://www.vfct.com/satellites/wheels/wheels2.html•http://scienceworld.wolfram.com/physics/ReactionWheel.html•http://www.thetech.org/exhibits_events/online/hubble/whichway.html•http://www.nasa.gov/centers/ames/research/technology-onepagers/advanced_min_wheel.html•http://www.vectronic-aerospace.com/html/reaction_wheel.html•http://www.thetech.org/exhibits_events/online/hubble/direction.html•http://fuse.pha.jhu.edu/educ/RW_FAQ.html•http://cubesat.ece.uiuc.edu/Teams/Attitude_Control.html•http://www.plus2physics.com/ecurrent_and_mgfield/study_material.asp?chapter=3•http://global.mitsubishielectric.com/bu/space/news/articles/image/86tr6.pdf01/13/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-4To explore further •http://staff.ee.sun.ac.za/whsteyn/Papers/Magsat.pdf• http://ocw.mit.edu/NR/rdonlyres/Aeronautics-and-Astronautics/16-358JSystem-SafetySpring2003/B169A368-9DCC-4916-8897-12B0DE4DC855/ 0/hete.pdf•http://www.sti.nasa.gov/tto/spinoff1997/t3.html•http://www.nasa.gov/centers/ames/research/technology-onepagers/advanced_min_wheel.html01/13/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-5Operational InterfaceFrom ECE 5320 class slides01/13/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-6Attitude Control•Attitude Control determines and monitors the direction of a spacecraft. Small mistakes could lead the spacecraft miles off course. Thus, it is important to have accurate sensors and actuators on board the spacecraft. Spacecraft attitude systems usually consist of two components:Spacecraft orientation sensors: magnetometers, gyroscopes, etc…; andControl actuators: e.g. reaction wheels, torque rods, etc…01/13/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-7Attitude ControlFigure from mitsubishielectricTable thanks to GoodrichAttitude Controll parameters01/13/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-8Major ApplicationAn example of spacecraft control. “The Hubble is the size of a large bus, travels at 17,500 miles per hour and is 370 miles above the Earth's surface. How do you point it at a tiny speck in the universe millions of light-years away and hold it steady, sometimes for hours at a time, so it can take a picture? (Hubble direction)”The answer is using a system called the Pointing Control System. The main components of the pointing control system are reactions wheels. The reactions wheels can be moved to change the orientation of a body. The reactions wheels spin quickly in one directions and the satellite rotates the other way to conserve angular momentum.Figures are from hypertech01/13/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-9Reactions WheelsIn order to keep the satellite steady or pointed in the right direction reaction wheels, or momentum wheels are used. Reactions wheels exert torque forces on the satellite to control its direction. The spinning flywheel is placed on the body of the aircraft and with a variable rate of rotation from an electric motor the spacecraft can be re-aligned.Picture from NASA spin-off Momentum Storage (h): h = TD*(Orbital Period/4)*(0.707) Slew Torque: Θ/2 = (1/2)*(T/I)*(t/2)2 Angular momentum: 0.4 to 400 Nms @ 1200 to 1500 rpm Weight: 2 to 25kg Power: 8 to 150W01/13/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-10Reaction WheelsStandard Momentum / Reaction Wheels Hamster Terrier Bearcat Nittany Lion T-RexN-m-s 0.1 1.0 5.0 50.0 75.0Size (in.) 4x4x6 4x4x6 4x6x6 6x6x6 6x6x7Weight 0.7 lbs 1.5 lbs 2.8 lbs 4.5 lbs 6.8 lbsPeak Power 1 W 5 W 10 W Launch Vibration DampeningYES YES YES YES YESSpin During LaunchNO NO NO NO NOPressure Housing NONE NONE NONE NONE NONESpeed (Nominal) 8,000 8,000 8,000 8,000 8,000Speed (Max) 15,000 16,000 15,500 32,000 45,000mN-m Custom Custom Custom Custom CustomLife >200 years >200 years >200 years >200 years >200 yearsElectronics Included Included Included Included IncludedSpeed Control +/- 0.03% +/- 0.03% +/- 0.03% +/- 0.03% +/- 0.03%Table is from Valley Forge Composite Technologies01/13/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-11Reaction Wheels in SpaceThe axis of rotation for each reaction wheel is fixed. Do to this fact three reaction wheels are needed for each spacecraft. One for the x, y, and z components as illustrated in the figure bellow. Usually a fourth wheel is also added to relate the three other wheels.Figure is from CubeSat at UofINASA Ames’ Project Development Division has produced two generations of small advanced reaction wheels for use in robotic astronaut assistants and small spacecraft. The small reaction wheels are energy efficient. They are able to assist astronauts both inside and outside of manned space vehicles. Figure from NASA01/13/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-12Location of Reaction WheelsFigure is from hypertechFigure is from Harvard01/13/19ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuatorsSlide-13Torque Coils vs. Rods•Coils–Easier to implement–Linear response makes control requirements simpler–Lower cost to manufacture–Create stray magnetic fields•Rods–More
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