QUEEN BEE FINDER. James Dillenburg. Abhijeet Srivastava. Krishna Yarramasu. Final Report for ECE 445, Senior Design, Spring 2015.

Transcription

1 QUEEN BEE FINDER By James Dillenburg Abhijeet Srivastava Krishna Yarramasu Final Report for ECE 445, Senior Design, Spring 2015 TA: Ben Cahill 06 May 2015 Project No. 19

2 Abstract For our project we decided to build an Ultra High Frequency (UHF) Radio Frequency Identification (RFID) scanner that would be able to detect passive UHF RFID tags that are glued on to queen bees. Our project aims to reduce the time it takes for searching for the queen bee. By doing this, we hope to make requeening a commercially viable option for beekeepers. In theory, our designs work, which we will go in depth later on. But we weren t able to test out all of it as we burnt our printed circuit board (PCB). ii

3 Contents 1. Introduction Functions and Features Design Block Diagram Block Descriptions RFID tag Scanner Power Source Motors Casing Software Flowchart Design Verification RFID tag Scanner TX Circuit RX Circuit CLS Circuit Microcontroller Power Source Vibrating Motors Costs Parts Labor Grand Total Conclusion Accomplishments Ethical considerations Future work References iii

4 Appendix A Requirement and Verification Table Appendix B PCB PCB Layout PCB Burnout Appendix C Arduino Code iv

5 1. Introduction According to the Department of Agriculture, the global net worth of bees was $200 billion dollars. During the last years, the population of worker bees has been going down at an alarming rate. This phenomenon has been named Colony Collapse Disorder (CCD). The major reasons for CCD are increased use of pesticides (especially neonicotinoids), infections from mites, loss of habitat and changing bee keeping practices. For thousands of years, humans have been selectively breeding livestock for traits that are beneficial to productive activities Bees, like other livestock, can be selectively bred for certain qualities. There are a few major hurdles for making this a reality on a mass scale. One of these is the time it takes for beekeepers to locate the queen (who is the genetic lynchpin of the colony). This process can take anywhere from a few seconds to upwards of 20 minutes even for the most seasoned beekeepers. Our project aims to reduce the time it takes for searching for the queen bee. By doing this, we hope to make requeening a commercially viable option for beekeepers. In the following sections of the paper, we ll talk about the functions and features of the scanner, move on the design, then to the design verifications, then the cost analysis and finally the conclusion. 1.2 Functions and Features The RFID tags should be able to be glued onto a queen bee Ability to scan for a queen bee on a stack in a hive The handheld scanner will vibrate when the scanner is held over a queen The scanner should have an on/off switch to conserve battery 1

6 2 Design 2.1 Block Diagram As shown in Figure 1, the handheld device will consist of two parts: data collection (RFID reader scanning for the passive RFID tag) and the feedback (vibration feedback). Figure 1: High level block diagram of Scanner 2.2 Block Descriptions RFID tag The RFID tag chosen for our purposes is IM5-PK2525. It fits the following requirements: 4mm X 4mm, weighs 1 mg (a queen bee can hold up to 35 mg). The tag is powered by receiving a signal from the scanner and using that signal to generate its own return signal that is meant to be read by the scanner. Another reason for choosing this tag was that it has been used with bees before, researchers at the University of Tasmania, put these tags on bees to figure out bee movement patterns to generate a 4-Dimensional model of bee behavior Scanner The scanner consists of a transmitting circuit (TX), a receiving circuit (RX), a carrier leakage suppression (CLS) circuit, and an antenna. The scanner will also send signals to the microcontroller. The parts of the scanner are described in more detail below i Transmitting Circuit [1] The transmitting circuit (Tx) is responsible for generating a 900 MHz signal at ~30 dbm. To accomplish this, the circuit has several components. The modulator gets two signals from the microcontroller and a signal from the Voltage Controlled Oscillator (VCO) to generate the signal to be amplified by the power amplifier. The amplifier chosen as the power amplifier was Skyworks SKY LF, this amp has a gain of 40 db at 900 MHz, which 2

7 would have fried our passive tags, so to avoid that we decided to add surface acoustic wave (SAW) filters to attenuate the signal and remove all the noise for the transmission. Figure 2 shows a schematic of the Tx circuit. Figure 2: Transmitting Circuit Schematic Figure 3 shows a simulation of the Transmitting Circuit of power vs frequency. Vin is the red line in the simulation and it shows the power level of the carrier frequency of 20 khz. Vout is the blue line in Figure 3 and shows a power level of dbm which is above the required range. But this is an ideal situation and when we actually build the circuit there will be power losses due to the capacitors and inductors in the circuit. Figure 3: Power at input and output of the transmitting circuit 3

8 2.2.2.ii Carrier Leakage Supression (CLS) Circuit [1] The CLS has a unique responsibility to prevent the transmitting signal from the Tx from leaking into the receiving circuitry. The directional coupler directs the carrier signal and the imperfect signal from the antenna-carrier combination. The attenuator and the phase shifter both bring down the power of the carrier signal and shift it. The purpose of doing this is explained by the combiner which combines these two signals and filters out the carrier signal from the imperfect combination, which leaves just the antenna signal to go to the receiving circuit. Figure 5 shows the schematic of the CLS circuit. Figure 4: Carrier Leakage Suppression Circuit Schematic iii Receiving (RX) Circuit [1] The receiving circuit (Rx) is responsible for receiving the return signal from the tag once it is detected by the scanner. This part of the scanner has two components. The low noise amplifier (LNA) is responsible for removing any noise received by the scanner. The other component is the demodulator whose purpose is to interpret the signal that is received. Figure 5 shows a schematic of RX circuit. Figure 6 shows a simulation of the receiving circuit of power vs. frequency. To achieve this simulation we passed in a 920mhz signal at 0dBm to mimic the carrier suppression leakage circuit. The SAW filter and low noise amplifier (LNA) before getting to demodulator. The simulation above shows the output after the demodulator, so this is the portion that gets passed into the microcontroller. 4

9 Figure 5: Receiving Circuit Schematic Figure 6: Power at input and output of the receiving circuit 5

10 2.2.2.iv Power Loss in Air Calculation Power Loss in air is given by the equation below L = 20log10((4πd)/λ) (1) where d is the distance between the reader and the tag (in m) λ is the wavelength of the carrier frequency (in m) Desired d = 6 inches = cm =.1524 m Carrier frequency, f = 920 MHz, so λ = c/f, where c = 3E8 m/s so λ =0.326 m Therefore, the desired loss, L = db. Net Power Loss, Lnet= db This equation allows us to estimate how much power we re going to lose when our carrier signal reaches the tag in the typical use case (distance of 6 inches). This is important in order for us to understand the power loss over our desired reading distance v Antenna The antenna receives the carrier signal from the CLS circuit and transmits it to the tag. It also receives the return signal from the tag and sends it back to the CLS circuit vi Microcontroller Arduino Uno board is being used as the microcontroller. This microcontroller was chosen because we know how to program this board to interpret RF signals. The board isn t too big (2.7 inches by 2.1 inches) and it weighs 25g making it acceptable for a handheld device Power Source The power source should deliver the appropriate voltage (5 V to microcontroller and scanner, and ~3.2 V to the motor). These should be delivered at a minimum of 1 A. The power source will also have an on/off switch that triggers and LED to visually display when the device is on and off. It will also have a regulator that has the ability to pare down the voltage to 3.3 V Motors The motors should receive their input from the Arduino and should vibrate the entire casing of the device. This vibration will tell the user when the scanner is above a queen bee Casing The plastic casing surrounding the scanner, microcontroller, power source and motor will be designed to protect the key components of the device from the elements. It will also be designed in a way that can be easily held by a user. In order to create this plastic casing, we created a cad design of the object and then have it 3D printed in the Illinois MakerLab Software Flowchart Figure 7 shows the software flow for the Arduino UNO microcontroller. The analog input this block refers to the input coming in from the receiving circuit. In software, this input is sampled 100 times by the microcontroller and goes through a filtration algorithm as shown 6

11 below. It ultimately outputs a high to the motors when the analog signal is filtered and checked for meeting the threshold value. Figure 7: Software Flowchart 7

12 3. Design Verification 3.1 RFID tag Passive RFID tag that does not require a battery and is able to be read from 5 in +/- 1 in. To verify the distance of the tag, hold a ruler next to the tag and hold the scanner at some distance, scanner must output at the appropriate distance to get the necessary points. Unfortunately some traces got burnt due to narrow widths, so we couldn t test this block 3.2 Scanner TX Circuit TX circuit outputs a signal at 900 MHz +/- 40 MHz at 30 dbm +/- 3 dbm For the verification we will build the Tx circuit using the hardware components and use the vector network analyzer (VNA) to check to see if the signal meets the parameters. Unfortunately some traces got burnt due to narrow widths, so we couldn t test this block RX Circuit RX circuit receives and demodulates a 900 Mhz return signal from the antenna. Verification will be done by generating a return signal using a signal generator and testing the output at the demodulator using the VNA to see if the signal has been demodulated. Unfortunately some traces got burnt due to narrow widths, so we couldn t test this block CLS Circuit CLS circuit filters out the carrier signal from the imperfect received signal from the antenna. This will be tested by generating the carrier and antenna signals and using VNA to see if the carrier signal is filtered out from the combination of the two. Unfortunately some traces got burnt due to narrow widths, so we couldn t test this block Microcontroller Receives a signal from the scanner and outputs a high signal to the vibrating motor. To verify, we will generate an analog output and determine if the Arduino UNO is filtering this data to output a high at the appropriate time only using the serial port monitor. 8

13 Figure 8. Serial Port Monitor The serial port monitor shows the values coming in from the signal from the power supply. We re changing the voltage from 1.84 V to 1.98 V. The threshold in voltage is 1.96 V and the value for this threshold on the serial port monitor is approximately 400. As we can see, the serial port monitor demonstrates that a value above 400. This means that the code is accurately detecting when the input signal is high enough to send the appropriate output to the motor. 9

14 3.3 Power Source Power source sends a signal of 5 V +/ V and 1 A +/-.2 A To verify, we used a multi-meter to check the outputs at the power source and saw that power source met the above requirements. 3.4 Vibrating Motors Receives a signal from the microcontroller and turns on. We set up the Feedback block (Figure 1) on a breadboard and verified if the motors turned on when the they received a high signal from the controller. Figure 9. Vibrating Motor Shown on Breadboard 10

15 4. Costs 4.1 Parts Table 1 shows a cost breakdown of all the parts that were used in scanner. The third column (Cost) refers to the cost of buying 1 piece while coumn 5 (Actual Cost) refers to the multiplication of Columns 3 and 4. Part Manufacturer Cost ($) Qty Actual Cost ($) Modulator SYIQ- 895M+ Demodulator SYIQ- 895D+ SAW Filiters B3588U410 Antenna HG903RD- SM Power Amp SKY LF Mini-circuits Mini-circuits EPCOS/TDK L-com Skyworks LNA ADL5523 Analog Devices VCO CV055CL Crystek Attenuator AV101- Skyworks LF Directional Coupler Mini-circuits ADC Phase Shifter Mini-circuits JSPHS Potentiomenter ECE Store Voltage Regulator 5V ECE Service Shop Voltage Regulator ECE Service Shop V Battery Pack Eveready Capacitor 2.2 pf DigiKey uf DigiKey pf DigiKey pf DigiKey pf DigiKey pf DigiKey nf DigiKey pf DigiKey pf DigiKey uf DigiKey pf DigiKey Inductor 10 nh DigiKey nh DigiKey Resistor 8.06Ω DigiKey Ω DigiKey

16 680 Ω DigiKey Ω DigiKey PCB 4PCB Microcontroller Arduino Arduino Uno RFID tag (IM5- Hitachi PK2525) Wire Plastic Casing (100g) Illinois Makers Lab Motors DC 3V Amazon RPM 0.2A Mini Vibration Motor TOTAL Table 1: Part List 4.2 Labor Table 2 shows a cost break down of each member of the team Name Hourly Rate Total Hours Invested Total = Hourly Rate X 2.5 X Total Hours Invested Abhijeet $ $22, Krishna $ $22, James $ $22, Total 900 $67, Table 2: Cost Analysis of Labor 4.3 Grand Total Table 3 shows the grand total of project. Section Total ($) Labor 67, Parts Grand Total 67, Table 3: Grand total 12

17 5. Conclusion 5.1 Accomplishments The entire feedback block (see Figure 1) was built and tested. The entirety of the scanner was designed and there was a definite proof of concept. The simulations of the circuit demonstrated that the scanner could deliver the power necessitated to provide a greater than standard range of detection for the RFID tag. 5.2 Ethical considerations One consideration loosely tied to the IEEE Code of Ethics is the impact the project could have. The bee population is declining drastically and globally bees are responsible for pollinating a large number of crops. While the argument could be made that these crops could be manually populated by humans, this isn t really efficient. A successful implementation of our project could do a lot in helping bees become more genetically resistant to their ever more aggressive environment. In addition, IEEE Code of Ethics (7.8.1) states that engineers should make decisions that are consistent with public safety. While this isn t a huge risk beyond open circuitry for this project, we aren t fully aware of the effects of long term exposure to ultra high frequency on bees. We will be carefully consulting with Professor Gene Robinson along the way to ensure that this technology is indeed safe for bees as we go along. 5.3 Future work Make new layout of the PCB Use Voltage regulators instead of potentiometers on the PCB Use a smaller microcontroller, the Arduino UNO has more features than required for this project 13

18 References [1] Implementation of Low-Cost UHF RFID Reader Front-Ends with Carrier Leakage Suppression Circuit, International Journal of Antennas and Propagation Volume 2013 (2013), Article ID Available at: Accessed April

19 Appendix A Requirement and Verification Table Table 4 shows the Requirements and Verifications table. Requirement Verification Verified (Y/N) 1. RFID tag a. Passive RFID tag that does not require a battery and is able to be read from 6 in +/- 0.5 in 2. Scanner a. Tx circuit outputs a signal at 920 Mhz +/- 40 Mhz at 30 dbm +/- 3 dbm b. Rx circuit receives and demodulates a 920 Mhz return signal from the antenna c. CLS circuit filters out the carrier signal from the imperfect received signal from the antenna 3. Microcontroller a. Receives a signal from the scanner and outputs a high signal to the vibrating motor 4. Power Source a. Power source sends a signal of 5 V +/ V and 1 A +/-.2 A b. Power source sends a signal of 3.3 V +/ V and 1 A +/-.2 A through a voltage regulator a. To verify the distance of the tag, hold a ruler next to the tag and hold the scanner at some distance, scanner must output at the appropriate distance to get the necessary points a. For the verification we will build the Tx circuit using the hardware components and use the vector network analyzer (VNA) to check to see if the signal meets the parameters b. Verification of b will be done by generating a return signal using a signal generator and testing the output at the demodulator using the VNA to see if the signal has been demodulated. c. Finally the CLS circuit will be tested by generating the carrier and antenna signals and using VNA to see if the carrier signal is filtered out from the combination of the two. a. To verify, we will generate an analog output and determine if the Arduino UNO is filtering this data to output a high at the appropriate time only using the serial port monitor. a. To verify, we will use a multi-meter to check the outputs at the power source b. We will use a multi-meter to check the output after the voltage regulator N a. N b. N c. N Y a. Y b. Y 5. Vibrating Motor a. Receives a signal from the microcontroller and turns on Table 4: Requirements and verifications table a. To verify, we will send a high signal to the motors from the microcontroller and observe if they vibrate. Y 15

20 Appendix B PCB PCB Layout Figure 10 below shows the PCB layout. Figure 11 shows the actual PCB Figure 10: PCB Design on Eagle 16

21 Figure 11: Actual PCB 17

22 PCB Burnout Figure 12 shows the PCB burnout that didn t allow us to finish testing the PCB. The trace got burnt as it wasn t wide enough to handle the amount of current that went through it when we started tuning the potentiometer. Figure 12: PCB Burnout 18

23 Appendix C Arduino Code Figure 13. Arduino Code Part 1 This code defines the inputs and outputs and also sets up the bubble sort that s going to be used in the filtration algorithm. 19

24 Figure 14. Arduino Code Part 2 This portion of the code mainly sets up the inputs and the outputs for the Arduino and also reads in from the scanner input. 20

25 Figure 15. Arduino Code Part 3 This part of the code prints out the output to the serial port monitor, sets the motor high or low based on the threshold difference and also creates the 5 Hz signal for the baseband. 21