SIMS: Smart Inventory Management System

1
SIMS Smart Inventory Management System

• Group 37
• Masaki Negishi Anthony Fai
• ECE 445 Senior Design
• April 27, 2005

2
Introduction

• SIMS provides a cost effective solution for the
  management of inventory which leverages RFID
  technology.
• Combines an antenna array to a single RFID reader
  to map out an area for inventory detection

3
Features

• PC serial interface
• Compatible with RFID Readers and Antennas
• Up to 8 outputs per unit
• Expandable, modular design

4
The SIMS System
5
System Overview

• Hardware
• Power Supply, PC Interface Processing Unit, RF
  Switching Unit
• TI HF RFID Reader, TI HF RFID Antenna, TI HF RFID
  Transponders
• Software
• PC control for antenna switching

6
System Overview
7
Hardware Overview (In House Manufactured)

• Power Supply
• Takes 6Vdc from AC/DC wall converter and converts
  to stable 5Vdc
• PC Interface Processing Unit
• PC communication with system
• RF Switching Unit
• Switching of RF signal from reader to selected
  antenna

8
PC Interface Processing Unit

• PIC Microprocessor
• RS232 Serial Communication with PC
• Sends output to RF Switching Unit

9
PC Interface Processing Unit (Schematic)
Thin colors will not have good contrast on a
projector
10
RF Switching Unit

• Takes in input from RFID reader
• Four outputs per board (expandable)
• Relay switching

11
RF Switching Unit (Schematic)
12
PIN Diode Switching Unit (Eliminated)

• Employ PIN Diodes for Switching
• Great performance for small peak to peak AC
  signal (low power)
• Poor performance for large peak to peak AC signal
  (high power)
• Introduce impedance mismatch

13
Power Supply (Main Idea)

• Supplies 5 Vdc and GND to switch and control
  units
• Maximum current 1A
• More stable compared to 5V from the wall

14
Power Supply (Schematic)
Thin colors will not have good contrast on a
projector
15
Hardware Overview (Outsourced)

• TI RFID S6500 HF Reader
• TI RFID HF Transponders
• TI RFID HF 13.56 MHz Antenna
• (RI-ANT-T01A)

16
TI RFID S6500 HF Reader

• RFID Reader
• Necessary to read and write to transponders
• Can be connected to PC through RS232
• Operating Frequency of 13.56 MHz (HF)
• Output voltage of 48 V peak-to-peak
• Power output of 4 W

17
TI RFID HF Transponders

• Transponders
• Receives 13.56MHz of the signal from the reader,
  and sends back a signal to the reader
• Consists of a loop antenna and a chip
  microprocessor

18
Factors Influencing Communication with Tags

• Orientation of tag with respect to antenna
• Environment around tag (e.g. metals, liquids)
• Background Noise

19
Recommendations for Tag Placements

• Parallel to antenna
• Away from metals
• Within reading range of antenna (25 cm)

20
TI RFID HF 13.56 MHz Antenna

• Used to transmit and receive signals.
• Used for Magnetic
• Tuned at 13.56 MHz
• Input Impedance of 50 Ohms

21
Loop Antenna (In House)

• Followed Texas Instruments Antenna Cookbook
• 50cm x 50cm
• Made of copper tape and wooden board
• T-matching network
• Reading range of 1 mm (SWR 2.2)

22
Loop Antenna (Self-Made)
Thin colors will not have good contrast on a
projector

• Measurement Results (SWR 60.832)

23
Loop Antenna (RI-ANT-T01A)

• Dimension 337mm x 322mm x 38mm
• Matched to 50 Ohms
• Maximum Reading Range 50cm

24
Loop Antenna (RI-ANT-T01A)
Thin colors will not have good contrast on a
projector

• Measurement Results 1 Vertical, Away from Metal
• SWR 1.004

25
Loop Antenna (RI-ANT-T01A)
Thin colors will not have good contrast on a
projector

• Measurement Results 2 Horizontal, Sitting on
  Lab Table
• SWR 1.636

26
Loop Antenna (RI-ANT-T01A)
Thin colors will not have good contrast on a
projector

• Measurement Results 3 Close to Lab Equipments
• SWR 5.111

27
Overall Z-Parameters
Thin colors will not have good contrast on a
projector

• SIMS System Antenna Results During Operation
• SWR 1.349

28
Factors Influencing Antenna Impedance

• Orientation
• Environment (e.g. metals, liquids)
• Noise
• Antenna is operating always in near field since
  wavelength is 22 meters!

29
Antenna Recommendations
Too must text on this slide

• The antennae must be placed first, and then must
  be tuned to the correct frequency.
• May need multiple antennae at one station for
  more complete coverage (this would help avoid
  nulls from environmental factors)
• Will need a larger antennae to achieve a longer
  reading range
• We do not completely trust the antenna cookbooks
  because they are unreliable!
• We suggest buying one antenna first, then analyze
  it and make sure it meets your specifications.

30
Software

• PERL software
• Takes in user input and sends out two HEX digits
  through RS232 serial port (I/O)
• PIC software
• Takes in input from RS232 serial port and sends
  logic high to corresponding pins

31
PERL Software

• Serial.pl
• Takes in keyboard inputs in HEX
• Must read header AF followed by two HEX digits
  (e.g. AF06)
• Send out input from COM 2 to PIC
• Checks to see if PIC received correct signal

32
PIC Software
Please do not include blocks of code. Small
amounts of pseudo code is just fine.

• Switch0331.hex example code
• use Win32SerialPort
• my com_port1 new Win32SerialPort ("COM1")
  die "Can't open serial port COM1 E\n" unless
  (com_port1)
• com_port1-gtbaudrate("9600")
• com_port1-gtdatabits("8")
• com_port1-gtstopbits("1")
• com_port1-gtparity("none")
• com_port1-gthandshake("none")
• com_port1-gtwrite_settings die "\nUnable to
  write settings for COM1"
• my (in1_count, in1_string) com_port1-gtread(1)
  read 1 byte
• if (in1_string ne '')
• my temp Ascii2Hex(in1_string)
• print "\nCOM1 Input in1_string 0xtemp
  (in1_count bytes)\n"
• print "\nCOM1 - Data to Send in Hex (default
  data) 0x"
• my tmp ltSTDINgt chomp tmp data tmp

33
Room Setup

• Map out room and give coordinates to each antenna
• For example, antenna B-2 can correspond to the
  secretarys desk

34
Future Hardware Development

• Improved Switching Unit for longer lifetime and
  higher signal isolation
• Increased number of antenna outputs
• Improved Antenna Design
• Larger loop antenna
• More stable impedance matching network and BALUN

35
Future Software Development

• Friendly user online interface (HTML)
• Information processing on transponder data
• Network with central server

36
RFID Frequency Comparison
Frequency Pros Cons
LF (100 140KHz 2.5 km) Read Range 100 cm MAX Magnetic Inductive Transponders Less susceptible to environment Longer reading range than HF Only usually one transponder can be read at a time Tags bulkier and more expensive than HF ones and less memory capacity
HF (13.56MHz 22m) Read Range 50 cm MAX (current antenna 25 cm) Magnetic Inductive Transponders Anti-collision intelligence allows multiple of tags to operate concurrently Well defined magnetic field More susceptible to environment Short reading range
UHF (860 960MHz 33 cm) Read Range 9m MAX Electric (but passive tags) Capacitive Transponders Anti-collision detection Long reading range Not well defined electric field Field nulls near antenna requires complex anti-collision intelligence Tags have less memory capacity
37
SWOT Analysis of SIMS
Strengths Modular design Supports LF and UHF Minimize number of readers Cost effective
Weakness Short range Susceptible to environmental factors Relay power consumption and lifetime
Threats Smart Shelves RTLS
Opportunities Inventory Management UHF implementation Software Expansion
38
Credits

• Mr. Richard Martin Cantzler, II
• Professor P. Scott Carney
• Mr. Nicholas Soldner
• Professor Jennifer T. Bernhard
• Professor Steven J. Franke

39
Thank You