Indoor Positioning

1
Indoor Positioning

• Kalid Azad
• Advisor Prof. Littman (MAE dept)
• Co-advisor Prof. Cook
• Cs398 Project Proposal

2
Problem Description

• What is indoor positioning?
• Find your location accurately indoors (like GPS)
• Why is it important?
• Unsolved problem
• Indoor robots, underground surveying, detailed
  maps/directions

3
Why is it hard?

• GPS doesnt work indoors! No line of sight
• No obvious alternative
• Previous approaches Psuedo-GPS, IR signal
  strength, RF, ultrasonic/acoustic
• Indoor radio propagation not well studied
• Reflection, absorption from obstacles
• Walls/windows/doors have different delays
• Cost! No 100,000 atomic clocks allowed.
• Light travels 1 ft/ns
• Hard to measure propagation delays w/o good
  clocks
• Resolution
• Want 1 ft resolution (not room-level
  granularity)

4
Approaches

• My approach use phase differences
• Multiple transmitters send sine waves
• Receiver notes relative phase differences
• Calculates how many wavelengths away from
  transmitter
• Receiver solves for its position
• Or, transmit data to central server, which
  calculates position and sends it back (via
  wireless network)

5
My Approach
T2
T1
1 wavelength
Possible location
6
My Approach

• Advantages
• No atomic clock/synchronization, works on RF,
  good resolution, phase easy to detect
• Done before?
• On google, only found 1 paper describing use of
  phase differences
• Not done in hardware

7
Methodology, milestones, and deliverables

• Steps
• Extensive survey of current technology
• Create a method
• Develop algorithm, order hardware
• Develop software
• Proof-of-principle
• Web-based, GUI
• Implement in hardware

8
Methodology, milestones, and deliverables

• By checkpoint (1 month)
• Thoroughly examined existing technology
• Created algorithm
• Ordered hardware
• Begin coding software
• Deliverables
• Report
• Detailed description of algorithm
• Hardware Requirements
• Portion of software implementing algorithm

9
Methodology, milestones, and deliverables

• Remaining steps for semester
• Implement algorithm in hardware
• If possible, use on a vehicle
• Deliverables by end of semester
• Detailed algorithm
• Software implementation
• Hardware implementation

10
Methodology, milestones, and deliverables

• Difficulties
• A good algorithm is
• Cost-effective, precise, easy to implement,
  without atomic clocks/synchronization, robust
• Getting hardware to work properly
• No specialized hardware for my algorithm
• Method may not be as precise as planned

11
Methodology, milestones, and deliverables

• Fall-back plan
• Explain what I found with my algorithm
• Benefits, drawbacks, tradeoffs
• Measure position with the precision I can
• Find limitations, sources of errors, effect of
  various obstacles (walls, doors, windows)
• If it doesnt work
• Document what doesnt work, and why
• Lesson for others )