Initial Position Orientation Tracking System IPOTS

1
Initial Position Orientation Tracking System
(IPOTS)

• Group Members
• Keiichi McGuire Henry Pham
• Marc Takamori Scott Spiro

2
Outline

• Problem Description
• Approaches
• How It Works
• Test Results
• Current Status
• QA

3
Problem Description

• Design and implement a portable position and
  orientation tracking system for a hand-held
  device (such as a camcorder)
• Records the position and orientation of the
  device as it is carried by a person.
• Transfer data via USB or external storage media,
  to a personal computer for analysis of the
  devices motion.

4
Approaches

• Method 1
• Electromagnetic Position Tracking System
• Springs Electricity
• Magnetic Pulse Measurements
• Method 2
• Single Purpose IC
• Accelerometers
• Gyroscopes
• Analog Compass

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Analysis of both approaches

• EM Position Tracking System
• Sensitive to local magnetic fields
• Lack of background in advanced physics
• Costly
• Single Purpose IC Chips
• Feasible approach to solve problem
• Easily attainable parts

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How it Works

• Measuring movement (Inputs)
• Microcontroller
• Displaying live data (LCD)
• Storing and transferring data (MMC)
• Analyzing data to produce results

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How It Works (Measurements)

• Single Purpose IC Chips
• 3-D Accelerometer
• Measures 3 accelerations (x,y,z) in voltages
• Sensitivity of 800mV/g
• Maximum of /- 1.5g
• 1g 9.81 m/s2
• 3 Single rate Gyroscopes
• Measures angular rate change in voltages from the
  normal to the chip
• 1 Analog Compass
• 2 Sinusoidal waves offset to measure direction
  relative magnetic North

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Gyroscope
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Analog Compass
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How it Works (Schematic)
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How it works (Microcontroller)

• PIC18F4680 Microcontroller
• 40 pin
• USART, SPI, I2C Interfaces built in
• 3328 Data Memory
• 64k bites PROM
• Analog to digital converter
• External 20MHz crystal (instruction cycle 0.2us
  per instruction)
• And More!

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How it Works (Firmware)

• Used C programming with Microchip C18 Compiler
• Used modular programming for better organization
  of large program
• Main functionality is interrupt driven

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How it Works (Firmware)
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How it Works (LCD)

• Asynchronous serial interface
• Microcontroller will send ASCII characters
  through USART
• 16 x 2 characters
• 19200 baud rate

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How it Works (Sensor Interface)

• Total of 8 different sensors multiplexed into the
  analog to digital converter
• Microcontroller steps through all select line
  combinations to acquire all data (appx 20us
  between each sample)
• Delay is put in software to compensate for the
  time taken to switch inputs (appx 2us).

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How it Works (MMC)

• First Design
• (MMC/SD Breakout Board)
• Program FAT16 File System
• Second Design
• Use the uALFAT-SD Module
• 8 MB MMC card (compatible up to 512 MB)
• SPI Mode (Serial Peripheral Interface)
• Microcontroller (Master)
• uALFAT (Slave)
• FAT16 (also FAT12 and FAT32 compatible) File
  System to Save Data

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How it Works (µALFAT-SD)

• Second Design (Continuation)
• Send 1-byte Command to the Chips Firmware to
  Control File Activities
• RTC (Real Time Clock)
• Capable of Running off External Battery
• 5V tolerant I/Os.
• Requires regulated 3.3V.
• Reliable FAT stack source code
• 4,000 to 10,000
• Take more than 6 months to program

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How it Works (Sleep/Low Voltage Detect Mode)

• Both Functions use built in features of the PIC.
• LVD mode works like interrupt
• Software programmable to desired voltage
• Trigger interrupt
• Sleep
• Software programmable two step sleep
• Turns off all oscillators
• Goes to sleep after 2minutes of no use
• Combined
• At a lvd, a sleep timer is initiated to
  automatically put device to sleep in 2 minutes

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How it Works (Compiling Data)

• Matlab 7.0 used as development tool to create an
  executable file which will convert raw data saved
  on MMC/SD develop data
• Uses Rotation Transformation Matrices
• Outputs tabulated data in a new text file in
  meters and angles
• Account for sensitivity and errors using Kalman
  Filter

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How It Works (Data Conversion Software)
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ADC / LCD Test Implementation

• Implemented software to dump live data from
  sensors to LCD
• Initially voltage regulator created noise and
  made ADC unstable, so decoupling capacitor was
  used to filter out the noise
• Currently theres a bug from an unknown cause
  that is making one output unstable (floats around
  /- 100mV)
• Test points are made to probe to see if
  interrupts are occurring at the correct time for
  sampling and LCD output

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LVD Sleep Mode Test Results

• Testing was successful
• Implemented Timer3 to be counter for 2minute
  delay
• Used power supply and leds to successfully show
  that 2 minute countdown was initiated
• Microcontroller oscillators were stopped in sleep
  mode.

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FAT16/MMC Implementation Results

• First Design
• Looked for Sample FAT16 File System Code
• Second Design
• RS232 Serial Port / HyperTerminal Application
• Checked to see if we are able to create
  directories, files, and read files on the SD/MMC.
• Microcontroller PIC18F4680
• Wrote code that would initialize SPI mode and let
  us be able to write to the SD/MMC card.
• uALFAT is not being able to communicate with the
  microcontroller. We believe through
  troubleshooting that this problem is a hardware
  problem. Another uALFAT is on order right now.

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FAT16/MMC Implementation Results (RS232
HyperTerminal)
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FAT16/MMC Implementation Results
(Microcontroller PIC18F4680)
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Current Status

• Sensor voltages can be captured and displayed on
  the LCD
• Device can run off of 5 AAA batteries, however
  30minute run time not yet tested
• Skeletal structure of hardware complete
• Firmware mostly complete
• Product casing design not started
• Downloading data to the MMC card currently not
  working (hardware issue, communicating with
  vendor)
• Kalman Filter not implemented
• Conversion softwares file i/o portion is working
  but conversion math not implemented in software
• Trying to figure out cause of floating voltage
  from one sensor output

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Q A ??