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

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

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

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

5. 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

6. Reviewing Our Original Design
Harrison
Figure 1: Original Block Diagram

7. 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) = [ft]
65 [inches]/2.54 [cm/inch] = [inches] 25.59*tan(15) = [inches] in front of the sensor.

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

9. 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]

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

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

12. 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

13. 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

14. 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

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

16. 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

17. Hardware Overview
Chris
Figure 5: Final Block Diagram

18. PCB Layout
Chris
Figure 6: PCB Schematic

19. Board Schematic
Chris
Figure 7: Board Schematic

20. Motor Schematic
Richard
Figure 8: Motor Schematic

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

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

23. Debugging the Interface

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

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

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

27. The Final Product
Chris

28. 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

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

30. Questions

31. Resources
“Blind people safety project”. Faith Degirmenci, Abdessettar Ibourki, Morad Oumina. Proposal, Spring 2006
GPS Instampper for Apple iPhone <
“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, Print.
"Sam Wormley's GPS Errors & Estimating Your Receiver's Accuracy." Educational Observatory Institute. Web. 08 Feb <
Skytraq datasheet for Skytraq Venus634FLPx. <
"Switch Debouncing (Bounce-free Switches) Using NAND Gates - Electronics and Communications Engineering. Web. 21 Feb <
TI datasheet for MSP430F2274. <
TI datasheet for SN7400N. <

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