RSSI Signal/Distance

Indoor Positioning SystemWade JarvisArthur MasonKevin ThornhillBobby ZhangMentor: Dr. Kemin ZhouIPS RequirementsDesign a safe, user friendly system that will be able to accurately locate and track multiple objects within a given area. Ideally provide real time location and direction between the readers and the tags.Last at least 1 year from battery power. Overall, the system should operate at an estimated cost of $2000 for an area of 10,000 square feet.

XBee API ProgrammingXBee Transparent ProgrammingSerial.print(Hello World);Broadcast to all nearby nodesincomingByte = Serial.read();Reads 1 byte of data from Serial bufferXBee sends any incoming bytes through UART to ArduinoXBee API Programming

XBee API Programming

RSSI Signal/DistanceRSSI/DistanceFormula for Distance:

Fm = Fade MarginN = Path-Loss Exponent, ranges from 2.7 to 4.3Po = Signal power (dBm) at zero distancePr = Signal power (dBm) at distanceF = signal frequency in MHz

Trilateration TrilaterationTrilateration is used to estimate the location of the unknown node2D Trilateration3D Trilateration

2D TrilaterationDistances (d1,d2,d3) are measured by an RSSI signal.Therefore, there is a small unknown error for every distance calculated

2D trilateration2D TrilaterationMATLAB Simulation

Detection Device Detection DeviceInnovation ID-12 chip

Arduino Uno

RFID Cards

Detection DeviceEach RF card has a 12 digit unique IDLinked to an object in the fieldSending the ID to Matlab:Arduino CodeMatlab Code

Both codes have to be interfaced with each otherDatabaseEach unique ID is stored in the MATLAB database

Incoming ID will be compared to the IDs stored in MATLAB

After comparison, location of the object will be displayed on a graphical user interface

Power RequirementsPower RequirementsPortableLong Battery LifeUser-FriendlySafeRechargeablePowering DevicesRF tags lithium-ion polymer batteries

RF readers USB or DC power source

Battery & Battery LifePower Indicator CircuitIntegrate into our RF tagsCut-off voltage of 3.2vHysteresis of .05-.07vDrop from high to low will cause a signal to be sent from the tag to the host computer to alert the user to charge the battery.

Battery Indicator DemonstrationVideo HereDistance TestingDistance Testing: Old Antennas Tested the system using 1 reader and 1 tagReceived mixed results based on the orientation of the devicesWorks accurately when facing away from each otherResults varied when devices were facing towards each other

Actual DistanceCalculated DistanceAway8 m8 mOther Orientations8 m10-13 m

XBee Antenna On board antennaNon-uniform radiation pattern

Antenova Titanis AntennaProvided by Cameron groupMuch better radiation patternDead zone aboveSometimes too sensitive

Distance Testing: New AntennasTested the system using 3 readers and 1 tagReceived mixed results due to the environmentGround testing: Inconsistent varied resultsHeld up testing: Consistent accurate results

Actual DistanceCalculated Distance10 m10.5 m6 m6 m19.1 m 19 m21 m25 m2-D Trilateration TestsParade Grounds5 feet above ground (using stands)Tag location: [0,4]Results

EE Parking Lot5 feet above groundTag location: [0,0]Results

EE Parking Lot5 feet above groundTag location [0, 0]Results

EE Parking Lot5 feet above groundTag location: [2,4]Results

Gymnasium5 feet above groundsTag location: [0, 5]Results

Implementation of Matlab GUI

ConclusionBudgetProductIndividual PriceNumber OrderedTotal PriceLithium Ion Polymer Batteries$16.95 2$33.90 Arduino Uno$29.95 3$89.85 Arduino Fio$25.00 1$25.00 Arduino Fio Cable$20.00 1$20.00 Maxim 8212 Chip$3.75 2$7.50 ID-12 Chip$29.951$29.95RFID Card$1.952$3.90DC Power Supplies$1.906$11.40Project Enclosure Box$5.951$5.95Digimesh XBee 2.4 GHz$21.004$84.00Xbee Shield$24.954$99.80802.15.4 Xbee 2.4 GHz(RPSMA)$21.008$168.00Titanis Antenna$30.008$240.00RPSMA to SMA Adapter$6.998$55.92Total:$872.17Performance OutcomesWant to track multiple tagsError of no more than 1 meterUser friendlyMobileTag life of at least 1 yearLow costReal time trackingProblems Titanis antennas were too sensitiveMetal interferenceHumidity and temperatureMoved outdoorsRadiation patterns were not uniformChange XBee modules

Future DesignsImplement a wake-up circuitAuto-tune for environmental effectsBetter antennas for situation3D trilateration

System Demonstration

Questions?AcknowledgementsMr. Scalzo, Dr. Kemin Zhou, Cameron Group, and Electrical and Computer Engineering Department