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)
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)
15
Power Supply (Results)

• Vmax 5.023 V
• Vmin 4.975 V
• Max. Ripple 48.44mV
• Freqnency 95.057KHz

16
Hardware Overview (Outsourced)

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

17
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

18
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

19
Factors Influencing Communication with Tags

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

20
Recommendations for Tag Placements

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

21
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

22
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)

23
Loop Antenna (Self-Made)

• Measurement Results (SWR 60.832)

24
Loop Antenna (RI-ANT-T01A)

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

25
Loop Antenna (RI-ANT-T01A)

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

26
Loop Antenna (RI-ANT-T01A)

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

27
Loop Antenna (RI-ANT-T01A)

• Measurement Results 3 Close to Lab Equipments
• SWR 5.111

28
Overall Z-Parameters

• SIMS System Antenna Results During Operation
• SWR 1.349

29
Factors Influencing Antenna Impedance

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

30
Antenna Recommendations

• Antennae must be placed first, and then must be
  tuned.
• May need multiple antennae at one station for
  more complete coverage (and avoid nulls from
  environmental factors)
• Larger antennae for longer reading range
• Do not completely trust antenna cookbooks because
  they is unreliable! ? Buy one antenna first and
  analyze it.

31
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

32
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

33
PIC Software

• Switch0331.hex
• Takes input from RS232 and sends logic high to
  corresponding outputs
• Will only respond if header AF is seen
• Sends back to PC its output

34
Room Setup

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

35
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

36
Future Software Development

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

37
RFID Frequency Comparison
38
SWOT Analysis of SIMS
39
Credits

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

40
Thank You