RF Item Tracker by littleStrong

Last crawled date: 3 years, 3 months ago

Quick Summary:
Have you ever misplaced an important item (keys, phone, homework) and feel frustrated when finding it? This device solves your problem; the RF item tracker is an item locator. It works similarly to a metal detector, but with more precision, with one quick sweep, the pain of finding items is a thing of the past. Especially for students, we are not just required but expected to have all of our material presents. The device can make sure with a quick scan that all of your material is present. But, the item tracker in the current state has one of the main issues, which is when working with RF electronics; it is important to keep in mind the parasitics of the electrical components, or the device will lose performance, and the device can differentiate from different items. If I can redesign the design in the future, I will make sure the electrical parasitics is an account, and the sensor upgraded UHF Rfid. UHF Rfid allows read up to 30 meters and programmable tags to know what the item is. UHF Rfid will allow the RF Item Tracker to track inventory with ease. Unlike conventional barcode tracker where an employee has to scan individually. The UHF Rfid RF Item Tracker can sweep the area in an instant saving companies time. Furthermore, 3D printing strengthens the design. 3D printing allows the components to be embedded, making the design cost-effective and robust. This will allow for 3D printing electrical circuits a viable option for heavy-duty applications in the military, industrial industries, and space industries.
More Reading:
1) The device is an item tracker. Sometimes we misplace an item or store an object in a difficult-to-reach shot, but the person is usually unsure whether the object in that spot. The device allows the user to pinpoint the item and validating if the object is present. Unlike many trackers on the market, where the tag requires batteries, this device is passive, requiring only the power from the tracker, and it is the size of a grain of rice. The device works similarly to a metal detector but detects the receiver tags instead of metallic objects. Based on the tracker’s signal strength, the tracker can change the tone of the buzzer and can also display the distance from the tracker allowing the user to find the item.
2) There are many issues when designing the device. First, Research to understand the design parameters, inspiration, and design techniques. One major problem was creating the flat coils within the design. Fusion 360 is the program used to create the device. On Fusion 360 there is no flat coil option, so we used the coil option to create a spring structure. Then, the spring structure is “pinched” on the top to make a cone-shaped spring. Next, the contour of the spring body projected onto the sketch. Finally, a sweep function is performed to create a flat spring. It’s easier said than done as Fusion 360 produced a lot of errors one time, a subassembly is missing a polygon, which is fixed by removing a extrude function. There are many other issues not listed, but with the help of the internet, most problems are solved.
3) There are many issues with the current design that needs addressing in the next iteration. I’m only a beginner in electrons, so there will be design flaws. The device is not a 50-ohm impedance match, so there will be signal loss within the design reducing the device range. There are parasitics within the device not accounted for. There is a method to differentiate between different tags. Current conductive filaments on the market have high resistance, and contact resistance connections of the components difficult and costly. In the next design, iteration solves the problem with 50-ohm matching, and the circuit parasitics can be solved, by using a dedicated PCB designing software rather than manually routing the wires. The PCB design software will follow design parameters more strictly than manually routing will. The different tags can be tracked by using UHF RFID high-frequency RFID, allows for multiple tags track and allows for other features. The features can be a high and low sensitivity mode on high sensitivity mode, the user to find the general direction. In the low sensitivity mode, the user can pinpoint the item. The design is capable of commercial inventory tracking and logging. The only main problem stopping 3D printing PCBs is the conductive filament having a high resistance. Once the magnitude of resistance decreased, the 3D printing PCB will become a better alternative to traditional PCB manufacturing.
4) The design is built around 3D printing, with the new introduction to conductive filaments on the market. 3D printing PCB is become more viable, unlike conventional PCBs, 3D printing will unlock the third dimension allowing for the electronics embedded within the enclosure to become a single-piece design. It can be cost-effective in single-board manufacturing because, currently, there is a minimum order criterion. Most importantly, you can pause and start prints allowing for the electronics components to be embedded within the design, making the electronics robust allowing for military-type applications, industrial applications, and future space applications.
Designer’s Note: Currently, I am not an electrical engineer, and the design is based on my current understanding of electronics, so the device may not work. It currently stands as a prototype, a proof of concept that 3D printing is a viable option for manufacturing PCBs. On the other hand, for those who are interested to print and test the device, see the printer’s note and the components list, and to use the device attach the tag an object that want to track.Then, use the tracker to find the object, and to create the device, you will need to use silver epoxy to attach the components and the battery contacts because soldering will not work with the conductive filament and the conductive filament have high mechanical resistance. If the device is redesigned in the future, an epoxy mask will need to be designed for easy silver epoxy application. Another issue is the print requires white PLA filament. The color matters as white PLA contains TiO2. TiO2 will change the dielectric constant affecting the embedded capacitors. One major issue would be tolerance as some conductive traces are only 0.2 mm apart, making it difficult or impossible to print. Finally, I want to acknowledge the input that I have received from my parent to improve on the project.
Printers note:
This print is larger and cannot be printed on most small hobby desktop printers. The print also requires dual extrusion direct drive extruders (The conductive filament is flexible) with a minimum resolution of 0.2mm.
Prusa Research White PLA (manufacture specifications)
Nozzle temp: 215 c
Heatbed temp: 50-60 c
Electrifi Conductive Filament
Nozzle temp: 140 – 160c
Printer Speed: 15 – 45 mm/s
Resources:
Reference Sources
• 3D printed PCB reference -- https://www.nano-di.com/blog/2019-how-to-reduce-pcb-size-with-3d-printed-embedded-components
• Connecting multilayered coils -- https://www.semanticscholar.org/paper/Multilayer-stacked-coreless-printed-spiral-winding-Lee-Su/21c20cb6aca880ee6b204fe4043c42bb8ea0d245
• https://www.everythingrf.com/community/high-frequency-hf-rfid-tags-systems#:~:text=The%20High%20Frequency%20(HF)%20band,1.75%20MHz%20to%2013.56%20MHz.&text=These%20tags%20are%20usually%20passive,a%20power%20source%20or%20battery.
• Electrical resistivity & conductivity -- https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity
• Unity Gain Opamp -- http://www.learningaboutelectronics.com/Articles/Unity-gain-buffer
• Bias T -- http://lna4all.blogspot.com/2014/11/diy-bias-t.html
•
Programming of the MCU
• Capacitive Touch -- http://ardututes.weebly.com/capacitive-touch-game.html
• Faster arduino sampling -- https://blog.wildan.us/2017/11/03/arduino-fast-er-sampling-rate/
• Oled Drivers -- https://pastebin.com/G6x7tsge
Online Calculators:
• Tank Circuit Resonance Calculator -- https://www.allaboutcircuits.com/tools/tank-circuit-resonance-calculator/
• Parallel Plate Capacitor Capacitance Calculator -- daycounter.com/Calculators/Plate-Capacitor-Calculator.phtml
• Multilayer coil calculator -- https://www.circuits.dk/calculator_multi_layer_aircore.htm
• Resistance-Frequency-Capacitance Calculator -- https://www.pad2pad.com/calculators/resistance-frequency-capacitance/
Components List
• 5volt voltage regulator -- https://www.mouser.com/datasheet/2/389/cd00000444-1795274.pdf
• DPAK package -- https://toshiba.semicon-storage.com/ap-en/semiconductor/design-development/package/detail.DPAK.html
• 1206 ceramic capacitor 100pF, 0.33uF -- https://www.topline.tv/drawings/pdf/capacitors/SC1206.pdf
• ATmega328P -- http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf
• TQFP Standards -- https://www.lapis-semi.com/en/package/sizeqfp.html
• 16mHz Crystal -- https://datasheet.lcsc.com/szlcsc/1811141611_Yangxing-Tech-X49SM16MSD2SC_C12676.pdf
• Oled -- https://www.addicore.com/OLED-128x64-Monochrome-p/ad304.htm
• Buzzer -- https://www.cuidevices.com/product/resource/cmt-8530s-smt-tr.pdf
• Opamp size spec -- https://www.njr.com/electronic_device/PDF/package/SOT-23-6-1_E.pdf
• Opamp -- https://www.st.com/resource/en/datasheet/tsv991.pdf
• Thin Film Resistor specs -- https://www.mouser.com/datasheet/2/414/PCF-1528243.pdf
• Silver Epoxy IC bonding -- https://www.amazon.com/MG-Chemicals-Two-Part-Conductive-Adhesive/dp/B008UH4DB2
• RFID Stickers -- https://www.rfidinc.com/hf-13-56-mhz-rfid-labels
• Conductive Filament -- https://www.multi3dllc.com/product/electrifi/
• White Filament -- https://shop.prusa3d.com/en/filament/39-white-pla-filament-1kg.html
• mts-102 switch -- https://www.fasttech.com/product/7883300-mts-103-spdt-on-off-on-toggle-switch-10-pack
• 2-Pin SMD 3mm x 6mm x 2.5mm Tactile Push Button -- https://www.ebay.com/itm/5x-2-Pin-SMD-3mm-x-6mm-x-2-5mm-Tactile-Push-Button-Tact-Switch-Micro-Switches-/202654797585