Chris Stoddard, Harrison Rose & Richard Lew GPS Service Animal Collar By Chris Stoddard, Harrison Rose & Richard Lew

Overview Introduction Features Design Testing and Verifications Richard Introduction Features Design Testing and Verifications Future Work Q & A

Introduction ECE 498: JJM Global Positioning Systems Harrison ECE 498: JJM Global Positioning Systems Inspired by a guest speaker from ANSC 250

Objective To provide visually impaired people a fast, safe, and reliable method for exploring new points of interest Harrison

Features Turn-By-Turn Directions Chris Turn-By-Turn Directions Up to 5 locations can be recorded and stored Location accuracy within 5 meters Backtracking for all routes Two vibrating motors for executing routes 2-hour battery life Adjustable collar

Reviewing Our Original Design Harrison Figure 1: Original Block Diagram

Curb Detection Chris Originally planned as feature to avoid users from leaving the sidewalk Solution was to use ultrasonic range finder to detect curb edges After reviewing specifics, we decided that curb detection was not achievable tan-1(X/Y) = 15 Y = 2 [ft]/ tan-1(15) = 7.4641 [ft] 65 [inches]/2.54 [cm/inch] = 25.59 [inches] 25.59*tan(15) = 6.8585 [inches] in front of the sensor.

Ethical Issues Accuracy and Precision Reliable Battery life Richard Accuracy and Precision Reliable Battery life Safe Hardware for Animal Interaction

Determining Parameters Harrison GPS: Ephemeris data: Errors in the transmitted location of the satellite (3 [m] on average) Satellite clock: Errors in the transmitted clock of the satellite (2 [m] on average) Ionosphere: Errors in the corrections of pseudorange due to ionospheric effects (5 [m] on average) Troposphere: Errors in the corrections of pseudorange due to tropospheric effects (1 [m] on average) Multipath: Errors caused by reflected signals entering the receiver antenna (1 [m] on average) Receiver: Errors associated with the receiver such as noise, software, and biases. (1 [m] on average) Average Errors in GPS Navigation Solution: Average Error = [Ephemeris Error + Satellite Clock Error + Ionosphere Error + Troposphere Error + Multipath Error + Receiver Error] (Equation 1) = 3 [m] + 2 [m] + 5 [m] + 1 [m] + 1 [m] + 1[m] = 13 [m]

Converting Coordinates Chris Usually done in X, Y, Z Read in Lattitude, Longitude, Altitude but needs to measure in meters, not degrees 0.0026 minutes = 5 meters

Motor System Two motors Two different vibrations Turn (Left, Right) Richard Two motors Two different vibrations Turn (Left, Right) Stop (Both)

Original Turning System Chris Originally, turns were going to be pre-computed after the route was originally recorded However, we decided that this method was cumbersome and a real-time decision would be better Figure 2 and 3: X and Y coordinate Turn Errors with Noise

New Turning System Use the current heading reported by the GPS Chris Use the current heading reported by the GPS Calculate the next heading using the next two waypoints Using these two vectors, calculate the angular difference and use this to decide the turn direction

Route Recording Harrison To record a route, users press a button at each waypoint Each of these locations is stored sequentially in memory Supporting five routes, the memory holds five lists of waypoints

Route Recording MatLab Simulation Harrison Figure 4: Screen Capture of Route Record

Backtracking Richard Backtracking supports navigating an entire route backwards, or returning from a route before completion Order of waypoints pulled from memory controlled by backtracking

Hardware Overview Chris Figure 5: Final Block Diagram

PCB Layout Chris Figure 6: PCB Schematic

Board Schematic Chris Figure 7: Board Schematic

Motor Schematic Richard Figure 8: Motor Schematic

Testing MatLab Programs iPhone GPS Application Motor/Micro Interfacing ALL MatLab Programs iPhone GPS Application Motor/Micro Interfacing GPS/Micro Interfacing Field Position Testing

Success: Micro and GPS Interact Harrison Figure 9: Instamapper iPhone App Map

Debugging the Interface

Verifications Powering motor by itself Measuring output from micro Richard Powering motor by itself Measuring output from micro

Challenge: Motors and Micro Do Not Interact Richard Change transistor Change base resistor Inverting output from micro

Success: Motors and Micro finally Work Richard Used the same power supply for micro and motors

The Final Product Chris

Testing 1st point 2nd point 3rd point 4th point 5th point 6th point Average Test 1 2m 8m N/A 4m Test 2 9m 5.7m 5.57m Test 3 1m 5.3m 2.2m 3.125m Test 4 6.7m 0.7m 4.85m Test 5 5m 3m 2.75m Test 6 2.1m 3.7m 0.8m 6.3m 4.7m 2.5m 3.35m Chart 1: Turn Error Tests

Future Work Increase precision and accuracy Course Correction Harrison Increase precision and accuracy Course Correction Load routes from database Reliable curb detection

Questions

Resources “Blind people safety project”. Faith Degirmenci, Abdessettar Ibourki, Morad Oumina. Proposal, Spring 2006 GPS Instampper for Apple iPhone <http://www.instamapper.com> “GPS Tracking Device with DGPS”. Alex Stezskal, Algirdas Navickas, Vivek Thyagarajan. Proposal, Spring 2010 Misra, Pratap, and Per Enge. Global Positioning System: Signals, Measurements, and Performance. Lincoln, MA: Ganga-Jamuna, 2011. Print. "Sam Wormley's GPS Errors & Estimating Your Receiver's Accuracy." Educational Observatory Institute. Web. 08 Feb. 2012. <http://edu-observatory.org/gps/gps_accuracy.html>. Skytraq datasheet for Skytraq Venus634FLPx. <http://www.sparkfun.com/datasheets/GPS/Modules/Skytraq-Venus634FLPx_DS_v051.pdf> "Switch Debouncing (Bounce-free Switches) Using NAND Gates - Www.ECELab.com." Electronics and Communications Engineering. Web. 21 Feb. 2012. <http://www.ecelab.com/switch-debounce-NAND.htm>. TI datasheet for MSP430F2274. < http://www.ti.com/product/msp430f2274>. TI datasheet for SN7400N. <http://www.ti.com/lit/ds/symlink/sn7400.pdf>.

Special Thanks To… Tom Galvin Professor Scott Carney Professor Jonathan Makela Mark & Scott from the parts shop