48x48 Poster Template

1
Exhaust Emissions Analyzer
Client Ben Weatherman (National
Instruments) Advisor Dr. Arun Somani
Phil Nguyen, EE Ket-Bing Yong, EE
Joshua Lichti, CprE Jonathan Langford, CprE
May08-25
Design
Introduction
The system consists of electrical and mechanical
aspects, as well as a software interface. Method
Building a compact exhaust sensor challenges for
the team because most analyzers are bulky and
require high power. Input/Output
Specifications Input to sensor circuit Emission
exhaust Input to MCU Voltage between 0V and
5V Output CO2 percentage Hardware
Specifications Sensor up to 50 CO2, 0-50C,
lt200mW Microcontroller 0-50C, lt200mW, gt2 inputs
In a day when global CO2 levels are one of the
greatest concerns of society, surprisingly few
advances have been made in the field of portable
CO2 emission analyzers. Such a product has the
potential for tremendous marketability and could
drastically change the way people view their
cars.
Software Specifications Developed with NI
LabVIEW Windows OS support Filter and display
real-time CO2 readings User Interface
Specifications Graphical display of CO2 value
Requirements

• Problem
• National Instruments asked Team May08-25 to
  design, implement,
• and test an exhaust emission sensor that could be
  used on a
• moving vehicle.
• System Block Diagram
• The exhaust emission analyzer system will take
  the output
• signal from the CO2 sensor circuit, interpret the
  data with the
• microcontroller, and display it on a user
  interface.
• Operating Environment
• The system was designed to be able to generate
  valid, CO2 emission-level readings while being
  exposed to a wide range of environmental
  conditions
• 0C to 70C
• 0 to 80 humidity
• rain, ice, and snow

PCB Layout
Circuit Schematic
Software Class Diagram
The configuration for the Wheatstone bridge
allows for a 2 independent controlled sensing
scheme. A voltage is applied across pin 6 and 22
which results in Joule heating of Element 1
(R3). The change in resistance for our purpose
will come from the presence of gas which will
exhibit itself as a change in temperature to the
exposed Element. The circuitry allows for a 2
pixel sensing scheme where the filament of the
sensor is one leg of the bridge and a precision
matched pair resistor network of 10K ohms is the
bridge reference. A set point bias is set to
adjust signal size, but the use of high signal
increases aging of the device. The final Op Amp
amplifies the signal with depending on R16, with
the Gain 1 49.9K/R16.
Mirror Stand and Mirror Holder
Mechanical Design

• Non-Functional Requirements
• The software shall detect lost hardware and
  display an error within 1 minute of the loss.
• The system shall function at a temperature range
  of 0C to 70C.
• Market Survey
• From the market research found, wireless and
  portable exhaust gas analyzers are available.
• Prices range from 4000 to 5000, which is too
  expensive for a car owner. The goal of the design
  team was to build a portable exhaust analyzer at
  a much more affordable cost.

• Functional Requirements
• The system shall contain a sensor to measure CO2
  emission from a moving automobile.
• The system shall contain a hardware device to
  communicate information to a user interface.
• The system shall contain a microprocessor that
  will run LabVIEW Embedded software to interpret
  and display the data.
• Deliverables
• The completed exhaust emission analyzer project
  will be composed of
• CO2 sensor circuit
• CO2 measurement hardware device
• CO2 level calculation LabVIEW software

Implementation
Part Vendor Cost
Sensorchip CO2 ICX 150.00
Gold Mirror Edmund 40.00
Small Electrical Components Various 16.98
NI USB-6009 DAQ National Instruments 242.00
Phytec phyCORE-ARM7/LPC2294 Phytec 300.00
Total Hours 603.5

• Testing
• Component Testing
• Test all major components individually
• Ensure power consumption and temperature
  specifications are met
• System Testing
• Test full circuit with multi-meter, then Data
  Acquisition Card
• Vary temperature and concentration levels to
  ensure correct operation for all environments.
• Test Results
• Component testing Success
• System testing In Progress

Plan

• Work Breakdown
• The design team was composed of two Electrical
  Engineers and two Computer Engineers.
• The work was divided up as follows
• Electrical Engineers System Hardware, Sensor
  Circuit, and PCB layout
• Computer Engineers System Software, LabVIEW
  Embedded, and Microcontroller

Conclusion

• Team May08-25 successfully planned and designed
  an exhaust emission analyzer as requested by
  National Instruments.  The team also created a
  prototype of the system.  However, the team was
  not able to bring the prototype to full
  functionality.  
• Functional components of the prototype
• Sensor circuit
• Mirror and mirror stand
• LabVIEW software
• The electronics of the sensor are very sensitive
  to electrical and environmental change and
  getting the prototype to function properly under
  actual environment conditions will be something
  to work toward in the future.  Other possible,
  future improvements will include an air flow
  measurement unit in which the system will be able
  to calculate the percent of CO2 concentration as
  a function of time and a system to cool the
  exhaust air before it reaches the analyzer. 

• Resource Requirements
• CO2 sensor chip
• Parts for sensor circuit
• Gold mirror
• LabVIEW Embedded
• Microcontroller

• Risks
• Creating the system involved several risks
• Moisture build-up
• Vibration disturbance
• Temperature outside range specified
• Degradation of device from repetitive high
  concentration of CO2

• Non-functional components of the prototype
• Sensor's ability to accurately measure CO2 in all
  environments
• Optics and electronics of the analyzer

Project Schedule Planning Due 11/30/08 Design
Due 11/30/08 Implementation Due 3/22/08 Testing
Due 4/8/08 Documentation Due 4/8/08