Next Steps

1
AA236 Thrusters
Team Members Adam Collazo, Andy Sadhwani, Bill
Storck, Cedric Bayart, Mitul
Jambusaria, Olivia Billett, Pierric Jammes
2
AA236 Thrusters Team

• Active propulsion for nanosatellites using VACCO
  piezo-electric valves
• (For future mission)

3
Design Concept
2 identical 1 valves controlling flow of
iso-butane Liquid storage tank ? gas plenum ?
vacuum
Liquid valve
Thruster valve
Propellant storage tank
10-15 psi
120 psi
4
System Capabilities

• Low power
• To open valve 200 mW for 20 ms
• No power required to keep valve open
• 10 mN thrust
• 220 ms pulse ? 1.5 deg/s rotation rate
• 90 degree turn in 60 seconds

5
Tank Development

• Ideas?
• for a constant thrust bigger tank
• desired 24 cm3 plenum, 8.25 cm3 tank

6
Fuel Tank Material
Aluminum Vrs. Titanium
7
Calculate Requirments
8
Torquer coils / Hardware design

• Update on wire material polyimide
• Sizing Helmholtz chamber testing

9
Torquer coils / Hardware design

• Update on wire material polyimide
• Sizing Helmholtz chamber testing
• 1) rotation track magnetic field
• 2) magnetic fields measurements
• 3) dynamics (oscillations)
• Match calculations. 3 possible designs
• More dynamics calculations

10
Torquer coils / Hardware design

• Power
• - 0.12 W per coil (max 0.15W high T)
• - Several at the same time?
• Integration
• - One (Two) outside the CS, below the solar
  panels
• - "Movable" coil ?
• - Fix it to the CS structure ? Epoxy?

11
Attitude Determination Control

• Att. Determination
• 1) Predict position in orbit
• 2) Model B at this position
• 3) Compare with Bmeasured gt attitude
• 4) Gyros propagate
• Att. Control
• 1) Detumbling
• 2) Pointing
• gt Difficulties 2 axis control only at one time

12
Torquer Coil Actuation

• How to interface the coils with the flight MCU?

• Interfacing Effort
• Use of Off-the-Shelf H-bridge
• Enable pin is driven by PWM channels
• Use of MSP430 Timer B

• Status
• Breadboard Op-amp functional
• Fully Digital w/ timer B functional

• Long term issues
• Bipolar junctions dissipate power
• Max. estimated consumption 0.3W/coil
• FET technology to reduce dropout ?