Solar Car Data Collection System Matt Boyden Rene Dupuis Ryan Lavallee 4/8/08

Ryan Background  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.  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 would need to collect time dependent data and then provide for the data to be uploaded and analyzed for learning.

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 change the performance of the car

Matt System Diagram Data Collection Micro- Controller Motor IMotor VPanel IPanel V Wheel Sensor

Matt System Diagram Data Output Micro- Controller

Responsibilities  Ryan  Data Retrieval (PC end)  Excel VBA Programming  Circuit board layout  Matt  Signal conditioning  HC12 programming,  Data transmission to PC (HC12 end)  Rene  Wheel sensing design  Power Distribution  Casing Prototype  Website

Rene Power Source  Wheel Sensor requires 5V  Using (2) 3V Lithium Batteries in series for power up  Small and efficient

Rene Velocity Sensor Concept  Every time the wheel rotates the sensor triggers the Pulse Accumulator in the microcontroller  By knowing the wheel diameter and reading the accumulator value at regular time intervals we can calculate the speed of the car

Rene Velocity Sensor Circuit

Rene Reflective Object Sensor  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  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

Ryan Comparator Simulation

Rene Velocity Sensor PC Board Layout  4 wire connector from velocity sensor to main board for power and data retrieval

Rene Current Sensing  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

Matt HC12 Programming  Why we chose the HC12  What does the Program have to do  How it will be accomplished  Data Transmission to PC

Matt Why 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: → Read Data from A2D Ports → Read Data from Wheel Sensor → Store Data → On Request or Timeout: → Stop Recording Data → On Request: → Transfer Data to Computer → Erase Memory

Matt Programming Flow Chart Start Initialization of Various Processes Start Record? Transmit? Stop Record? Read Data Store Data Time Limit? Delay MAINRECORD

Matt Data Transmission  Data 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

Ryan PC Programming  How the Excel Program Works  Tutorial for Teacher  Importing Data to Excel

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:  Voltage Cell: A2D_V *  Current Cell: ((A2D_I*0.0049)/30)/0.15Ω  Automates graph wizard process for all data

Ryan File Contents  The goal is to give the teacher one file where s/he will be instructed to open only the excel file and run the macro

Ryan Board Layout  Circuit Circuit

RyanSchedule

Budget Item Cost CostActualCost 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 TOTAL$103.33$68.49

Questions?

Ryan