Transcript PowerPoint-presentation

Our PIC ”Kitchen Lab”
Who has said that PIC-processors aren’t
Rocket Science ?
William Sandqvist william@kth.se
REXUS
Rocket-borne Experiments for University Students
ESRANGE Sweden mar 2010
William Sandqvist william@kth.se
Mission, deploy a web in space
Mission
To deploy a net in zero
gravity
William Sandqvist william@kth.se
What to do with a web in space?
• Could be used as an Antenna?
• Could be a lightweight platform for
miniature crawling construction robots?
William Sandqvist william@kth.se
How to unfold a web in zero
gravity?
?
( when Fuglesang isn’t there to help )
William Sandqvist william@kth.se
First: How to fold a web?
Some Japanese origami is needed
This is the Miura-Ori folding scheme
From Mattias Gärdsback and Gunnar Tibert
William Sandqvist william@kth.se
Scater spinning on ice
Law of the Conservation of Angular
Momentum
Initial
Unfold
Rotation will slow down!
William Sandqvist william@kth.se
The ”spinning scater principle”
Rotate the hub with weights attached to the corners of the
web, then the centrifugal force will unfold the web?
Won’t Work!
The ”spinning scater priciple” can’t unfold the net.
 If the initial rotational speed is to low, the final centrifugal forces won’t
be strong enough to deploy the net.
 If the initial rotational speed is to high, the energy transfered from the
hub to the net will cause oscillations – then the net will be tangled.
William Sandqvist william@kth.se
Reaction wheel to ”help” the rotation
The stabilizing rotation of the web
centrifugal
force
Reaction
wheel
hub
William Sandqvist william@kth.se
Controled unfolding
Nice!
William Sandqvist william@kth.se
Simulation of the reaction wheel motor
voltage during controled unfolding
Simplified control is possible!
From Mattias Gärdsback and Gunnar Tibert
William Sandqvist william@kth.se
Gyro to sense
hub rotation
The gyro
Sensitivity: 5mV/ °/s
1 Hz (360°/s)  1.8 V
0.1 Hz
 0.2V
0.01 Hz
 0.02V
William Sandqvist william@kth.se
Reaction wheel controler card
With simplified control,
one simple PIC Micro could do the job!
Start now signal
Now ejected
signal
PIC Micro
E [V]
PWM
DIR
Gyro (x),( y), z,
temperature
RW
motor
Release the net signal
William Sandqvist william@kth.se
First PICKit 2 and breadboard
William Sandqvist william@kth.se
Zero gravity on earth?
Problem: motor cold not move flywheel!
The gravity caused friction in the bearings.
When the flywheel was lifted with a string
everything worked! Zero gravity on earth!
William Sandqvist william@kth.se
Board layout, and manufacturing
Our LKPF facility
William Sandqvist william@kth.se
Wait for:
Esrange Februari/March 2010
Sorry: We didn’t deliver a working
board in time.
(and there were other problems
elsewhere)
William Sandqvist william@kth.se
The Orion rocket
No PIC-processor in space (this time)
William Sandqvist william@kth.se
William Sandqvist william@kth.se
Circuitboard with testprogram
A degree project was performed by student Andreas
Svensson in order to assure that we in the future, given a
second chance, have a board that works,
Circuitboard and
testprogram.
a auto test
m motor test
g gyro test
l led test
s signal test
write command:
William Sandqvist william@kth.se
Demonstration with PICKit2
UART Tool
a auto test
m motor test
g gyro test
l led test
s signal test
write command:
William Sandqvist william@kth.se