SSP Presentation Template

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Guidance, Navigation and Controls Subsystem
Winter 1999 Semester Review
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Outline

• Team Overview (Greg Chatel)
• Attitude Determination (David Faulkner)
• Attitude Control (Brian Shucker)
• Simulations (Barry Goeree)

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Team Members

• Team 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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Generalized GNC System
Kalman Measurement Update State Update Covarian
ce Update
Dynamic System Model State Propagation Covarian
ce Propagation
Control Software Standby Star Pointing Horizon
Track Ground Track Power Gen. Emergency
Instruments Magnetometer Sun Sensors Rate
Gyros Horizon Sensor
Control Hardware React. Wheels Torque Rods
External References
Satellite Motion
Attitude Estimation Update
Attitude Estimation
Measurement
Control Commands
Attitude Estimation
Control System
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Attitude Estimation Sensors

• GPS
• Magnetometer
• Sun Sensor
• Horizon Sensor
• Star Tracker
• Integrating Rate Gyro

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Control Software Overview
Command given
Initialize Software
Look for Command
Execute Command
No command
Initial Diagnostic
Running Diagnostic
Determine Desired State
OK
Start Standby Mode
Attitude/Position Update
Input from Attitude Estimation
Startup
Attitude Adjustment
Output to Reaction Wheels
Problem
Problem
Check Reaction Wheel momentum
Output to Magneto-torquers
Recovery Algorithm
Interface
Momentum handling
Main Control Loop
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(No Transcript)
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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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Attitude Control Simulation

• Whats 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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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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Attitude Control Devices

• Dynacon Mini Reaction Wheels
• Size 80 x 80 x 100 mm
• Power 2.5 W ea _at_ 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