aquatic spectrometer & turbidity meter ece 4007 l1, group 8 paul johnson daniel lundy john reese...
TRANSCRIPT
Aquatic Spectrometer & Turbidity Meter
ECE 4007 L1, Group 8Paul JohnsonDaniel Lundy
John ReeseAsad Hashim
Introduction & Background What is it?
A device to detect the colour and clarity of a uniform flowing water sample
How does it work?LED’s, a diffraction grating, a photo-detector array and an on-board PC
Why do we need it?Demand from Aqua-culturists and Water Regulation Authorities for a cheap and easy to use device
High Level Block Diagram
Key Components Electronics & Optics
Controlling the LED’s, collimating the light, obtaining a diffraction pattern
SoftwareDesigning code to interpret sensor data and provide useful information
Mechanical AspectsDesigning an enclosure, water proofing circuits and designing an interface with existing pipe fittings
InterfacingControlling LED power, and establishing two-way communication with photo sensor
Electrical Characteristics
PARAMETER MIN TYP MAX
Supply Voltage 4.75V 5V 5.25V
Supply Current 450mA 725 1A
Operating Temperature -20° +70°C
Bandwidth 1Hz 30Hz
Micron vs. Kodak Image Sensor
Micron Kodak
Cost $30 $14
Speed 30fps 580fps
Resolution 1280 x 1024 126 x 96
Sensitivity 2.1V/lux-sec 22V/lux-sec
Notes Larger active area Discontinued
Micron Image Sensor 10bit parallel data
bus 1MHz – 48MHz I2C control
LED Control Independent LED
control 3V IO lines OFF for dark current
measurement Transmission
measurement Scatter measurement
Single Board Computer TS-7250 ARM9 Single Board Computer
200 MHz 32 MB RAM
Programming in C
Compiling with special ARM9 compiler obtained from vendor
Networking software with wireless networking capabilities
Four source files: Main.c SquareWave.c Process.c Networking.c
Software Flow Chart
BeginProgram
Compute turbidity
Set up Program
Store resultsDetermine colorTake in serial data
Turn LED's on andoff
SpecMain.c
SquareWave.c
Process.c
Networking.c
Establishconnection
Send data
Photo Sensor Interfacing Sensor will be clocked at 1.3 MHz
A 1 byte intensity value corresponds to each pixel on the sensor
Sensor acts as a slave device controlled by the SBC
Computer will communicate with the sensor through 8 data lines.
Each wavelength’s intensity value must be multiplied by the inverse of the sensor’s white curve at that particular wavelength to normalize the overall spectrum
Color Analysis - Obtaining Spectrum Values
Intensity values are obtained via serial connection
Values are stored in a vector
Vector is divided into 3 (or more) regions
Total intensity of each region is calculated
The resulting regional intensities are compared to each other and stored as ratios
Ratios are compared to predetermined ratios from known algae samples to determine the algae's growth stage
Spectrum Division
Turbidity Analysis Regional intensities from color analysis are
summed to create an overall intensity
The weaker the overall spectral intensity, the greater the turbidity
Intensity to turbidity conversion will be calibrated by finding the spectral intensities of various samples of water with known turbidities
Networking (if time permits…)SBC sends resulting data to a centralized web server which can
be accessed remotely by computer
Scheduling
Parts Cost Analysis
Part CostLEDs $9
SBC $184
CMOS Image Sensor $14
Optics Kit $10
Power Supply $20
Misc. Hardware $120
Total $357
Marketing & Cost Analysis
Development Costs:Parts: $357Labour: $50,000
Final Price: $1499.99 Includes parts, marketing, overhead,
labour, testing and assembly Expected Revenue: $374,998 Expected Profit: $91,445 (24.4%)
Conclusions Electronics
Controlled LED’s through power control module and designed photo sensor board
OpticsDesigned collimating apparatus and positioned diffraction grating & photo sensor
MechanicalDesigned enclosure and interfaced with existing pipe fittings
SoftwareProgrammed SBC to provide information on colour and clarity of water sample based on ‘dummy data’
InterfacingHave yet to establish useful two way data communication between SBC & photo sensor
Questions?