Download - Guidance, Navigation and Controls Subsystem
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Guidance, Navigation and Guidance, Navigation and Controls SubsystemControls Subsystem
Winter 1999 Semester ReviewWinter 1999 Semester Review
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Guidance, Navigation, and Controls
Outline
• Team Overview (Greg Chatel)
• Attitude Determination (David Faulkner)
• Attitude Control (Brian Shucker)
• Simulations (Barry Goeree)
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Guidance, Navigation, and Controls
Team MembersTeam Mentor:• Dr. Fasse (AME)
Team Members:• Matt Angiulo (AME)• Greg Chatel (AME)• David Faulkner (AME)• Marc Geuzebroek (Phys)• Barry Goeree (AME)• James Harader (AME)
• Marissa Herron (AME)• Steve Hoell (Phys)• Brian Ibbotson (AME)• Martin Lebl (CSC)• Adam Mahan (ECE) • Brian Shucker (Phys/Math)• Daniel Stone (AME)
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Guidance, Navigation, and Controls
Generalized GNC System
KalmanMeasurement
Update
StateUpdate
&Covariance
Update
DynamicSystem Model
StatePropagation
&CovariancePropagation
ControlSoftware
StandbyStar Pointing
Horizon TrackGround TrackPower Gen.Emergency
Instruments
MagnetometerSun SensorsRate Gyros
Horizon Sensor
ExternalReferences Measurement
SatelliteMotion
AttitudeEstimation
Update
Attitude Estimation
ControlHardware
React. WheelsTorque Rods
AttitudeEstimation
Control System
ControlCommands
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Guidance, Navigation, and Controls
Attitude Estimation Sensors
• GPS• Magnetometer• Sun Sensor• Horizon Sensor• Star Tracker• Integrating Rate Gyro
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Guidance, Navigation, and Controls
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Extended Kalman Filter Block Diagram-- Discrete Measurement Updates-- Continuous Dynamic Propagation Models
In from instruments
Out to controller
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Guidance, Navigation, and ControlsControl Software Overview
Initialize Software
Start Standby Mode
Look for Command
Running DiagnosticInitial Diagnostic
Recovery Algorithm
Execute Command
Attitude/Position Update
Attitude Adjustment
Check Reaction Wheelmomentum
Momentum handling
Determine Desired State
OK
Problem
Command given
No command
Problem
Output to Reaction Wheels
Output to Magneto-torquers
Input from Attitude Estimation
Main Control Loop
Startup
Interface
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Guidance, Navigation, and ControlsBasic Control Modes
Standby
Max Power Generation
Position satellite foroptimum solar panelperformance
Photometry Experiment
Inertial pointing at star
Lightning/Sprite Experiment
Point at limb of the earth
Laser Experiment
Track ground stationin Tucson
Error Recovery
Detumbling
Momentum Management
Deployment
Acquire Satellite Error Detection
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Guidance, Navigation, and Controls
Attitude Control Simulation
• What is simulated?– Torques acting on satellite determine how attitude
changes with time. These equations of motion are integrated in time.
– This is different then what STK does!
• What are we trying to achieve?– Obtain accurate estimates for important design
parameters like max torque and momentum storage.
– Analysis and verification of control and attitude estimation algorithms.
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Guidance, Navigation, and Controls
Attitude Control Simulation
• What’s included in the simulation?– aerodynamic drag torques
– magnetic field models
– sun sensor model
– dynamics of satellite, orbital kinematics
– control algorithms
– simple visualization
– kinematics of ground station tracking
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Guidance, Navigation, and Controls
Attitude Control Simulation
• What needs to be done?– solar pressure
– gravity gradient
– attitude estimation algorithms
– models of all other sensors (magnetometer, horizon sensor)
– continue work on control algorithms
– kinematics of other control modes
– more realistic visualizations
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Guidance, Navigation, and Controls
Attitude Control Devices
• Dynacon Mini Reaction Wheels– Size: 80 x 80 x 100 mm
– Power: 2.5 W ea @ 2000 RPM
• Optional integrated rate sensor: 1 W
– Angular Momentum Capacity: 0.3 N-m-s
• Student Designed Torque Rods– lost our Space Grant student
– found a detailed paper on designing torque rods