Transcript whitek final presentation

In and Out Line Monitoring System
for Volleyball
Kelley White
Advisor: Professor Buma
What problem will this project solve?



A line judge determines if a ball lands in or outside the
court
There is a need to ensure good calls and a fair game for
players and coaches
Develop a system that can determine if a ball lands on the
line
Specifications
 The prototype will be a 6
foot portion of the end
line
 Thin line to ensure safety
for players
 Battery powered and
rechargeable (able to last
a 10 hour tournament day)
 LED light indicating ball
contact
 Simple installation with
overlying tape over
existing line
 Cost effective
Block Diagram
Input from sensor
microcontroller
Indicator (LED)
Sensors
 9 force sensitive resistors
(FSR’s) that are 2 feet long
each and have ¼” sensing
section
 Each sensing section will be 2
feet long and contain 3 FSR’s
The Design
 Most important specification factor is safety
 The height of the line from the gym floor will be no larger than
0.5 mm thick
 Negligible to players
0.5 mm
2” wide tape
3 FSR’s
wires
2” wide double
sided tape
Testing
ΔT=0.258 sec
Running
ΔT=0.026 sec
Ball Bounce
Testing
Scenario
ΔT (seconds)
Bounce
0.026
Hard Hit
0.038
Soft bounce
0.014
Step
0.516
Run
0.258
Two Foot Jump
0.612
Microprocessor
 Arduino Uno R3- receives voltage signal from one or multiple two
foot sections
 Output LED light at the Arduino for ball contact and no light for
foot contact
Algorithm
Detect an input
voltage pulse
Start Clock
Pulse ends stop
clock
Duration less
than 100ms?
NO
YES
Light off
Light on
Final Testing: Part One



Accuracy of the Arduino paired with the sensors will ultimately
determine how well the system works
Using four different scenarios, 10 trials each: walk, two foot jump,
bounce, and hard hit
Mean
Standard
Mean percent error of 4.14%
Scenario
Percent
Deviation
Error
for all scenarios combined
Walk
2.17%
1.73%
Two Foot
Jump
3.77%
1.90%
Bounce
4.01%
2.13%
Hard Hit
6.62%
2.84%
Final Testing: Part Two
No light
LIGHT
Conclusion
Goal
Success?
Safety
Maybe
Power/battery
Maybe
Cost effective
Maybe
Easy installation
No
Accuracy/ Does it work?
Yes!
Future Work:
1. Expanding to the whole court
 180 foot perimeter
 90 two foot sensing sections
 Analog/digital MUX
Future Work:
2. Ensure Accuracy
 Need to test all types of contacts
- An impact that barely touches the end
sensor
- A high velocity ball that rolls over the
sensor(s)
- Any false positives from body contact
on the line
Future Work:
3. Recovery time
 An FSR’s resistance changes every time there is an impacting force
 With continuous force on the same sensor, the resistance of the sensor may not
go back to its “normal” resistance before the next impact
 This can cause the system to miss a ball contact on the line
Questions?
Appendix
Budget:
Stage:
Part:
Purpose:
Price
Force Sensitive Resistors
(9) FSR 408
Needed to send signal to microprocessor
$161.55
Microprocessor
Arduino Uno R3
Converts input to output
$39.38
Op amps
(3)LM358
Part of circuit
*
Resistors
(3)820K ohm
Part of circuit
*
Resistors
Part of circuit
*
Battery
9V lithium ion battery
Power for circuit
$3.81
Wires
Soft flex wire
Thin, durable wire to connect components
$11.69
Tape
3” wide tape
Tape for transportation
$15.70
Tape
2” wide
Tape for overlaying line for prototype
$6.58
Battery holder
9V enclosed battery holder with on/off switch
Encloses power for circuit and Arduino
$2.95
Indicator
LED
Provides output for ball contact
*
Encloser
Arduino Uno and Ethernet shield transparent
acrylic case
Holds Arduino, solder board and battery pack
$6.95
Cable Sleeving
Smart Power Supply Cable Sleeving Kit
Holds all of the wires together
$9.95
TOTAL
The * indicates the component will be covered by the ECE department.
$258.56
Thickness:
Basic scotch tape: 0.058 mm
Wires: 0.2546 mm
FSR’s: 0.40 mm
Max total thickness: 0.40+0.058= 0.458 mm
*will be negligible to players
Resistor Data
Parallel v. series
One FSR is hit, resistance will have more
of a change in parallel than in series.
Therefore it is more accurate to have them
is parallel.
All FSR’s are hit, overall resistance in
lower in parallel and series. Less of a
drastic difference here.
+9V
FSRs
LM358
820K
Vout
RM= 820K
Highest resistance suggested is 100K, but
this is only for small forces
Tested with 100K, 500K, and 820K and
the 820K gave the clearest output signal
FSR’s
1.75”x1.5”
$7.95
.5” diameter
$6.95
.16” diameter
$5.95
Arduino Uno v. Arduino Mega
Specifications:
1. Pins: Need at least 4 digital pins
2. Memory rate: Unneeded. Processing real time data to make the output
decision. Not storing any outputs/inputs.
3. Sampling rate: 10 samples a second worked well for differentiating force,
100 samples a second worked very well with the scope, 50 samples a second
would ensure enough accuracy
4. Small enough current draw to ensure 10 hour running time on a 9V battery
Arduino
Type
Price
Number of
Digital Pins
Memory
Sampling
Rate
Current
Draw
Arduino Mega
2560
45.95
54
256KB
16MHz
500mA
Arduino Uno R3
24.95
14
32KB
16MHz
50mA
Power
The system needs to work for a full 10 hour day tournament
Current draw:
Microprocessor: 50mA
LED: 3mA
Op amp: 45nA
FSR’s: 0.11mA (each)
Total consumption: 54.035mA
Battery Capacity/current draw= number of hours
Battery Capacity=540.35 mAH
**Need lithium ion 9V battery with 620 mAH