A Tri-Axial Accelerometer Interface For The Transmission...
Transcript of A Tri-Axial Accelerometer Interface For The Transmission...
A Tri-Axial Accelerometer Interface For TheTransmission Of Impact Measurements
Heather Marandola SUNFEST 2000Advisor: Jim Ostrowski
Figure 1 [1] Figure 2 [2]
General AthleticAccelerometer Applications
Figure 3 [3]: Rowing ApplicationFigure 4 [4]: Hockey Application
The Accelerometer
• What is an accelerometer?
• Defining Characteristics– ‘g’-rating
– sensitivity
– axes
• Choosing the proper accelerometerEntran Devices [5]
EGA Miniature Accelerometers(3.56 x 3.56mm to12.7 x 12.7mm)
The Evaluation Board
T2
T1 A( g) = (T1/T2 – 0.5)/12.5%0 g = 50% DUTY CYCLE
PeriodRset
M=
( )WW125
F dBk xC
FC
( )( ( ) ( , )) ( , )
3 12 32 2 3
52 3
==pm
W
Noise rmsg
Hzx BWx( ) .=
5001 5
md ia f[6]
[7]
[8]
[9]
[10]
Accelerometer Data Evaluation
Vcc
GND
VccGND
GND
Vcc
0 500 1000 1500 2000 2500 30001
2
3
4
5
6
7x 10
4
0 500 1000 1500 2000 2500 30001
2
3
4
5
6
7x 10
4
reading reading
Zero Acceleration Raw DataAccelerometer
attached to a blockat the end of the pendulum rod,axes oriented
as shown
Experimental Setup
xyA
C D
B
0 5 0 0 1 0 0 0 1 5 0 0 2 0 0 0 2 5 0 0 3 0 0 0 3 5 0 0 4 0 0 0 4 5 0 03
3 . 5
4
4 . 5x 1 0
4
0 5 0 0 1 0 0 0 1 5 0 0 2 0 0 0 2 5 0 0 3 0 0 0 3 5 0 0 4 0 0 0 4 5 0 03.8
4
4.2
4.4
4.6
4.8
5
5.2x 1 0
4
A
A
B
C
B
D
B
C
C
BB
D
B
B
D
B
C
B
D
B
reading reading
67 Degree Pendulum Swing
0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 00
1
2
3
4
5
6
7x 1 0
4
0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 00
1
2
3
4
5
6
7x 1 0
4
A
AB
B
CC
DD
E
EE
E
reading reading
‘A’ indicates the release point of the pendulum‘B’ indicates the point of the first impact with the wall‘C’ indicates the point of the second impact with the wall‘D’ indicates the point of the third impact with the wall‘E’ indicates the pendulum’s recoil period
67 Degree Impact
Accelerometer Data Evaluation (cont.)
0 100 200 300 400 500 600-1.5
-1
-0.5
0
0.5
1
1.5
0 100 200 300 400 500 600-1.5
-1
-0.5
0
0.5
1
1.5
g’s g’s
reading reading
A A
A AB
BC
CD
D
‘A’ ‘B’ ‘C’ ‘D’ ‘A’
x
x
xx
x
y y
y y
y
Calibration Test
0 5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 3 5 0-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0 5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 3 5 0-1
-0.5
0
0.5
1
1.5
2
2.5
g’s g’s
readingreading
0 5 0 1 0 0 1 5 0 2 0 0 2 5 0-12
-10
-8
-6
-4
-2
0
2
4
0 5 0 1 0 0 1 5 0 2 0 0 2 5 0-6
-4
-2
0
2
4
6
g’s g’s
reading reading
Acceleration Display Mechanism
Display Acceleration Range (g’s)0 0 to .250* .25 to .750** .75 to 1.25“ “0******************** 9.75 to 10.25Overload > 10.25
Display Mechanism
Transmission & Reception
Linx Technologies LC Series Wireless Data Modules
315 Hz Transmitter: 315 Hz Receiver:
Benefits:• low cost• low power consumption• very compact [11]
[11][11]
Other Transmission Considerations
• Choosing an Antenna
• Data Encoding
The “Splatch” 0.062” thick(easily concealed)
The Scenix Microcontroller
[12]
[13]
Transmission/Reception Eval Boards
Vcc
GND
Vcc GND
GND
Vcc
x-infrom accelerometer
y-in
GND
Vcc
GND
GND
Scenix Programmer: In from PC (Sxkey)
Data out from microcontroller,into transmitter
Vcc
GND
VccGND
GND
Vcc
Vcc
GNDGND
Scenix Programmer: In from PC (Sxkey)
Data out from receiver, intomicrocontroller
RF in (ant)
RS232 Communication
ACCELPIC
data acquisitionand RS232
communication
TX RX
PIC
conversion from series to parallel
PC
S 1 0 0 0 1 1 1 1 S S 1 0 1 0 0 1 0 1 S S 1 0 0 1 1 0 0 0 S S 1 0 1 0 0 1 0 1 S
1st x-byte 2nd x-byte 1st y-byte 2nd y-byte
S 1 0 0 0 0 0 0 0 S
Transmitting the #1:
Transmitting the x-zeroing value (42265) and the y-zeroing value (42489)The four byte serial output to be sent is:
1010010111111001 (x-accel) 1010010100011001 (y-accel).
Conclusions
• Preliminary filtering, scaling, & display mechanisms completed
• LC Series transmitter and receiver of sufficient caliber
• Transmission board capable of sending RS232 data across RF link
• Reception board capable of converting series to parallel
• Link must be established between the transmitter and receiver
The Future
Accelerometer applications within impact monitoring systems are numerous. I believe the future of this device
lies in the development of wireless interface system compatible with each of the applicable environments - a universal accelerometer interface requiring only minor
alterations when switching from one application to the next.
1. http://www.exploratorium.edu/hockey/checkig1.html2. http://members.tripod.com/Yale_Football/yale.html3. http://www.analog.com/industry/iMEMS/markets/consumer/sports_training/sports_tr.html4. http://www.geocites.com/SunsetStrip/Palms/2366/ozolinsh.html5. http://www.entran.com/ega.htm6. http://www.analog.com/industry/iMEMS/products/X1210eb.pdf7. http://www.analog.com/pdf/ADXL210_10_b.pdf8. http://www.analog.com/pdf/ADXL210_10_b.pdf (pg 7)9. http://www.analog.com/pdf/ADXL210_10_b.pdf (pg 8)10. http://www.analog.com/pdf/ADXL210_10_b.pdf (pg 7)11. http://www.linxtechnologies.com/f_modules.html12. http://www.linxtechnologies.com/f_antenna.html13. http://www.scenix.com/tools/parallax.html
References