Initial Position Orientation Tracking System (IPOTS)

Group Members:

Keiichi McGuire Henry Pham

Marc Takamori Scott Spiro

Outline

Problem Description Approaches How It Works Test & Results Current Status Q&A

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 device’s motion.

Approaches

Method 1: Electromagnetic Position Tracking System

Springs & Electricity Magnetic Pulse Measurements

Method 2: Single Purpose IC

Accelerometers Gyroscopes Analog Compass

Analysis of both approaches

E&M 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

How it Works

Measuring movement (Inputs)

Microcontroller Displaying live data

(LCD) Storing and

transferring data (MMC)

Analyzing data to produce results

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/s^2

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

Gyroscope

Analog Compass

How it Works (Schematic)

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!

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

How it Works (Firmware)

How it Works (LCD)

Asynchronous serial interface Microcontroller will send ASCII

characters through USART 16 x 2 characters 19200 baud rate

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).

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

How it Works (μALFAT-SD)

Second Design (Continuation) Send 1-byte Command to the Chip’s 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

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

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

How It Works (Data Conversion Software)

Get Accelerometer

Data (x,y,z) relative to ground and compute roll

and tilt.

Can we use analog compass? (+/- 10 from

vertical?)

Set angles of Camera by

Accelerometer Readings

NO

YES

Get Compass

Data

Set compass and accel. Readings to

set initial coordinates

Get Gyroscope readings

(x,y,z)

Perform Stabilized Angle Calculations

Add Initial Angles

Rotation MatricesB=R*A

Record position and orientation

Start

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 there’s 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

LVD & Sleep Mode Test & Results

Testing was successful Implemented Timer3 to be counter for

2minute delay Used power supply and led’s to

successfully show that 2 minute countdown was initiated

Microcontroller oscillators were stopped in sleep mode.

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.

FAT16/MMC Implementation & Results (RS232 & HyperTerminal)

FAT16/MMC Implementation & Results (Microcontroller PIC18F4680)

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 software’s 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

Q & A ??