Transcript Solar Car Data Collection System

Solar Car Data Collection
System
Matt Boyden
Rene Dupuis
Ryan Lavallee
4/23/08
Background
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Building miniature solar
cars is a very common
activity for teaching
school-age kids about
renewable energy
There are events
specifically designed for
building and racing solar
cars that are available as
educational kits
Ryan
Project Description
What is needed is a small, light data
logging device specifically designed to
interface with a typical educational solar
car kit.
 The data collection system will collect data
on voltage, current and speed, every ½
second.
 The data will allow educators to output
graphs of distance, speed, acceleration,
voltage, current, power and energy vs.
time.

Ryan
Project Requirements
Record voltage and current to the motor for
a specific amount of time
 Interface with a computer to easily output
the information in a way that can be used
for educational purposes
 The product must be light enough and use
little power so as not to significantly change
the performance of the car

Ryan
System Diagram
Matt
System Diagram Data
Collection
Matt
System Diagram Data Output
Matt
Design Outline
Speed, Current and Voltage Sensing
 Microcontroller Programming
 The User Interface
 Circuit Board Design and Layout
 Enclosure Design
 Project Management

Matt
Speed, Current, and
Voltage Sensing
Rene
Velocity Sensor Concept
 Every time the wheel rotates the sensor triggers the Pulse
Accumulator in the microcontroller
 By knowing the wheel circumference and reading the
accumulator value at regular time intervals we can calculate the
speed of the car
Rene
Reflective Object Sensor
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Consists of an infrared
emitting diode and NPN
silicon phototransistor
mounted side by side
Phototransistor responds to
radiation emitted from diode
when it senses a reflective
device
Provides
 High output sensing no
reflection
 Low output sensing
reflection
Rene
Comparator
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Velocity sensor output runs
into comparator
Eliminates hysteresis and
rise times when changing
states (high to low; low to
high)
Provides quick transition
intervals as comparator
changes states
Provides sure output
Rene
Comparator Simulation
Rene
Velocity Sensor Circuit
Rene
Current Sensing
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Use Resistor to measure
current to motor
0.15Ω resistor will not affect
motor performance
Easy to install in series with
clip leads
Voltage will be amplified
x30 and converted to
positive voltage before A-D
converter
Rene
Voltage Sensing
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Voltage will be read
directly off of the
panel with an A-D
convertor.
The voltage and
current values will
also be used to
calculate power and
energy
Rene
Microcontroller
Programming
Matt
Microcontroller Programming
We will use a Motorola HC12
microcontroller
 What does the Program have to do
 Data Transmission to PC

Matt
The HC12
Has Analog to Digital Converters
 Has RS232 Chip Built into Module
 16kB Flash Memory for Data
 Easily programmed using available
software
 Can be programmed on docking module
then transferred to application

Matt
Program Requirements
→
On Request:
→
→
→
→
On Request or Timeout:
→
→
Read Data from A2D Ports (Voltage and Current)
Read Data from Wheel Sensor (Speed)
Store Data to Flash Memory
Stop Recording Data
On Request:
→
→
Transfer Data to Computer
Erase Memory
Matt
Data Transmission
Current, Voltage and Speed information is
sent one number at a time through an
RS232 connection
 We are using Hyper Terminal to receive
the data and capture it to a text file
 From here, the data will be available on a
PC to be accessed by the VBA program

Matt
The User Interface
Ryan
PC Programming
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How the Excel
Program Works
User Interface
Outputs
Ryan
How VBA Program works
Program references .txt file
Places .txt file in predefined rows
Excel programmed to make calculations and
produce graphs of all the data
Calculations:
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Voltage Cell: A2D_V * 0.0049
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Current Cell: ((A2D_I*0.0049)/30)/0.15Ω
Velocity: (PA(t) – PA(t-1)) * Wheel circumference
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0.5 seconds
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Automates graph wizard process for all data
Ryan
User Interface
Ryan
Outputs
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Each graph will be displayed on a
separate page in Excel
Ryan
Circuit Board Design and
Layout
Ryan
Board Layout Methodology
This is the circuit board
that we designed. This
will contain the
Microprocessor, and
any circuitry required.
This board must be
small enough to fit on
the solar car and as
light as possible.

Circuit
Ryan
Case Design
Rene
Design
Rene
Design Dimensions
Rene
Project Management
Matt
Responsibilities

Matt
 Signal
conditioning
 HC12
programming,
 Data
transmission to
PC (HC12 end)

•
Ryan
 Data Retrieval (PC
end)
 Excel VBA
Programming
 Circuit board layout
Rene
• Wheel sensing
design
• Power
Distribution
• Casing Prototype
• Website
Schedule
Week
Task
Programming HC12:
Flowcharts
Read Data
Store to Flash
Transmit Data to Computer
Excel Programming:
Read from .txt File
Output Graph
Sensor Selection:
Define Options
Collect Data Sheets
Choose Wheel Sensor
Choose Current Sensor
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Battery Selection:
Select a battery to power HC12
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Circuit Layout:
Build Circuit on Breadboard
Run Circuit to Record Data
Design PCB
Make First PCB
Wheel Sensor:
Sensor Design/Selection
Wheel Sensor Data Collection:
Transfer Wheel Data Into Speed
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Design Casing:
Casing Design
Casing Prototype
Final Case Production
Manuals/Instructions:
Manual/Instruction Writing
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Budget
Item
Cost
Actual
Cost
HC12
$30
$0
Solar Car
$50
$50
Reflective Sensor
$2.86
$0
3V Lithium Battery
(2)
$1.98
$0
Op-amp
TLV 2772 (3)
$6.75
$6.75
Ribbon Cable(2)
$10.00
$10.00
Comparator
$1.74
$1.74
Resistors, LEDs,
Pushbuttons etc
$20.00
$0
TOTAL
$123.33
$68.49
Matt
Next Steps in the Design Process
Write our own communications program
instead of using Hyper Terminal
 Finalize casing with smaller and lighter
components
 Use ‘power saving’ options on HC12 to
lower power consumption and improve
battery life
 Meet with educators

Matt
Questions?
Back
Ryan