Indledning og Modellering

1
MIEMA Microgravity Isolation Using
Electomagnetic Actuators
2
Microgravity
Regulering
Isolation
3
Microgravity
Regulering
Isolation
4
Microgravity
Isolation

• Not completely 0-g on ISS
• Manouers
• Astronaut movements
• Motors running
• Etc.
• Microgravity (mg) is about 10-4 g on the
  shuttle.
• Required atteuation x1000
• Experiment examples
• Crystals for protein research.

5
Microgravity
Regulering
Isolation

• MIEMA isolated an experiment from disturbances
  and actively removes them.
• Free-floating platform with 6 degrees of freedom

Pitch Roll Yaw Forward/Backward Sideways Up/Down
6
Microgravity
Regulering
Isolation
Requirements to the System

• Control of all 6 degrees of freedom
• Dampening of the internal platform with respect
  to the outer structure

7
Microgravity
Regulering
Isolation
Requirements to the System

• Control of all 6 degrees of freedom
• Dampening of the internal platform with respect
  to the outer structure
• Noncontact actuators
• Sensors
• Acceleration sensors
• Position sensors

8
Microgravity
Regulering
Isolation
Max displacement 0.25 mm
acceleration 1 mg
9
Microgravity
Regulering
Isolation
Max displacement 0.25 mm
acceleration 1 mg
Revised levels
Max displacement 5 mm
acceleration 200 mg
10
Microgravity
Regulering
Isolation
Sensors and Actuators
11
Microgravity
Regulering
Isolation
Sensors and Actuators
Accelerometers

• Placement
• 12 sensors
• 6 accelerometers
• 6 Position sensors
• 6 Actuators

Position sensors
Actuators
12
Microgravity
Regulering
Isolation
Sensors and Actuators

• Accelerometers
• MS7002
• 200 mg resolution

• Position sensors
• Infrared emitter/receiver
• Range /- 5mm
• Resolution 0.5mm

13
Microgravity
Regulering
Isolation
Sensors and Actuators

• Accelerometers
• MS7002
• 200 mg resolution

• Position sensors
• Infrared emitter/receiver
• Range /- 5mm
• Resolution 0.5mm

• Actuators
• Electro magnetic design
• Voice-coils principle
• Allows /- 5mm movement

14
Microgravity
Regulering
Isolation
15
Microgravity
Regulering
Isolation

• External
• Magnetic link
• Aerodynamic link
• Mechanic link
• Frequency/mass dependencies

16
Microgravity
Regulering
Isolation
Controller design

• Current controller
• Acceleration controller
• Position controller

Current controller
System
17
Microgravity
Regulering
Isolation
Current Controller

• Attenuates disturbances in the current
• Saves computational power
• Removes actuator dynamics

18
Microgravity
Regulering
Isolation
Acceleration Controller

• Robust and classical design
• Band-pass filter look
• BW 100 Hz

19
Microgravity
Regulering
Isolation
Position Controller

• Cascade coupling of position and acceleration
• BW 1Hz

20
Microgravity
Regulering
Isolation
21
Microgravity
Regulering
Isolation

• Impossible to test on earth.

22
Microgravity
Regulering
Isolation
2 x Parabolic Flight
23
Microgravity
Regulering
Isolation
Results
24
Microgravity
Regulering
Isolation
Results
xd
xdiff

• About 50 times attenuation