SIMS: Smart Inventory Management System Group 37 Masaki Negishi & Anthony Fai ECE 445 Senior Design April 27, 2005

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

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

The SIMS System

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

System Overview

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

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

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

RF Switching Unit Takes in input from RFID reader Four outputs per board (expandable) Relay switching

RF Switching Unit (Schematic)

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

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

Power Supply (Schematic) Thin colors will not have good contrast on a projector

Hardware Overview (Outsourced) TI RFID S6500 HF Reader TI RFID HF Transponders TI RFID HF MHz Antenna (RI-ANT-T01A)

TI RFID S6500 HF Reader RFID Reader Necessary to read and write to transponders Can be connected to PC through RS232 Operating Frequency of MHz (HF) Output voltage of 48 V peak-to-peak Power output of 4 W

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

Factors Influencing Communication with Tags Orientation of tag with respect to antenna Environment around tag (e.g. metals, liquids) Background Noise

Recommendations for Tag Placements Parallel to antenna Away from metals Within reading range of antenna (~25 cm)

TI RFID HF MHz Antenna Used to transmit and receive signals. Used for Magnetic Tuned at MHz Input Impedance of 50 Ohms

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)

Loop Antenna (Self-Made) Measurement Results (SWR = ) Thin colors will not have good contrast on a projector

Loop Antenna (RI-ANT-T01A) Dimension: 337mm x 322mm x 38mm Matched to 50 Ohms Maximum Reading Range: 50cm

Loop Antenna (RI-ANT-T01A) Measurement Results 1: Vertical, Away from Metal SWR = Thin colors will not have good contrast on a projector

Loop Antenna (RI-ANT-T01A) Measurement Results 2: Horizontal, Sitting on Lab Table SWR = Thin colors will not have good contrast on a projector

Loop Antenna (RI-ANT-T01A) Measurement Results 3: Close to Lab Equipments SWR = Thin colors will not have good contrast on a projector

Overall Z-Parameters SIMS System + Antenna Results During Operation SWR = Thin colors will not have good contrast on a projector

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

Antenna Recommendations 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. Too must text on this slide

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

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

PIC Software Switch0331.hex – example code use Win32::SerialPort; my $com_port1 = new Win32::SerialPort ("COM1"); die "Can't open serial port COM1: $^E\n" unless ($com_port1); $com_port1->baudrate("9600"); $com_port1->databits("8"); $com_port1->stopbits("1"); $com_port1->parity("none"); $com_port1->handshake("none"); $com_port1->write_settings || die "\nUnable to write settings for COM1"; my ($in1_count, $in1_string) = $com_port1->read(1); # read 1 byte if ($in1_string ne '') { my $temp = Ascii2Hex($in1_string); print "\nCOM1 Input: $in1_string : 0x$temp ($in1_count bytes)\n"; } print "\nCOM1 - Data to Send in Hex (default: $data): 0x"; my $tmp = ; chomp $tmp; $data = $tmp; my $temp = Hex2Ascii($data); my $count_out = $com_port1->write($data); print "COM1 Output: $temp : 0x$data ($count_out bytes)\n"; Please do not include blocks of code. Small amounts of pseudo code is just fine.

Room Setup Map out room and give coordinates to each antenna For example, antenna B-2 can correspond to the secretary’s desk

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

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

RFID Frequency Comparison FrequencyProsCons 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

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

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

Thank You