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RFID Membuat Tenggang Waktu Tidak Menyakitkan di Tapak Pembinaan

Automasi; itu adalah teknologi moden hari ini!

Trek Masa Pembinaan
Trek Masa Pembinaan

Recently, Telaeris was asked to simplify employee time-keeping for a construction yard using radio frequency identification (RFID) technology. The company had 3000 employees and wanted to know both who was on the job site and when they came and left. Instead of hand punched time-cards which were tedious and error-prone, we provided them with an elegant, effective, and most importantly, automated solution. Here’s how it worked:

First, an RFID tag was placed on each employee hard-hat.

Seterusnya, kami meletakkan dua antena UHF RFID jarak jauh di setiap pintu. Memandangkan setiap pekerja melalui pintu dan antena, pembaca menangkap maklumat pekerja dan maklumat tag.

Akhir sekali, semua data ini secara automatik dimasukkan ke dalam kami Sistem dan pangkalan data XPressEntry. Kami mengesan tepat setiap kemasukan pekerja dan keluar setiap hari untuk mengira masa harian mereka. Tetapi yang lebih penting, kami menyimpan akaun berterusan tentang siapa yang berada di lokasi, jadi dalam kes kecemasan, majikan tahu dengan segera siapa yang sedang bekerja, meningkatkan keselamatan pekerja.

Itu sahaja!

It’s nice to have a system function so straightforwardly, but there are many factors which we had to consider for this project. Below is a in-depth explanation of the RFID technology behind it and what we based our choices on.

Tag RFID

When deciding on the tag placement and tag type for any situation, it is important to keep a few
faktor dalam fikiran:

Gunakan Persekitaran Kes: Dalam aplikasi pelanggan ini, tag itu akan selalu didedahkan kepada unsur-unsur - khususnya matahari dan hujan. Ia perlu cukup lasak untuk menahan pendedahan yang berpanjangan.

Ketahanan Teg Yang Diperlukan: Oleh kerana ini adalah untuk syarikat pembinaan, kami tahu teg ini akan terdedah kepada kotoran, habuk dan minyak setiap hari. Di samping itu, kami menjangkakan bahawa dengan kerja keras yang dilakukan oleh pekerja, tag-awalan itu dapat ditembusi agak sedikit.

HID Slimflex Tag
HID Slimflex Tag

Keperluan Pemasangan: Some customers are able to wear UHF cards in lanyards or have tags on wristbands for tracking their people. This customer wanted to have the tag affixed to the employee hard hat without modifying the helmet as this could damage the integrity of the helmet’s safety performance. This required a tag that was flexible enough to conform to the curved helmet and a strong adhesive that would hold it indefinitely.

Penempatan Lokasi Tag: We considered placing the tag on the inside of the hat to keep it more protected. However, an interesting fact about RFID tags is when they are too close to a human body, they become ineffective. Water, which makes up 60% of our bodies, absorbs RF energy. Having a tag placed on the inside of the hat near the back of the head, would likely decrease the tag read range. To improve the tag performance, we chose to place the tag on outside back of the hard hat. While this would leave it more exposed, it would provide more reliable tag readability. This location had the additional benefit of allowing us to better differentiate between entries and exits, by appropriate placement of the antennas.

Untuk memenuhi keperluan kami, kami memilih tag dari tag HID SlimFex tag UHF. Teg ini fleksibel dan tahan lama, dengan ciri-ciri bacaan yang hebat.

Antena

Sama seperti memilih tag, terdapat beberapa pertimbangan yang perlu dibuat apabila memutuskan ciri-ciri antena, polarisasi, nombor dan peletakan antena.

Ciri-ciri: Kita perlu untuk memeriksa keuntungan antena dan lebar rasuk. Keuntungan adalah kekuatan relatif tenaga yang boleh dihantar oleh antena. Lebar rasuk menggambarkan kawasan di mana antena boleh membaca tag. Kedua-dua faktor berkaitan dengan jarak satu teg boleh dibaca dari antena. Menentukan had dan lebar rasuk yang diperlukan untuk aplikasi boleh menjadi perbezaan antara kejayaan dan kegagalan dalam pemasangan. Sebagai contoh, jika anda cuba menjejaki seseorang sebagai

Beamwidth and Gain
Beamwidth and Gain

mereka melewati pintu, tetapi tidak mahu membacanya melalui dinding, anda mahu lebar lebar rasuk dan keuntungan sederhana. Untuk aplikasi kenderaan, keuntungan tinggi dan lebar rasuk sempit lebih cenderung diingini.

Polarisasi: Seterusnya untuk dipertimbangkan ialah polarisasi antena. Antena pasif UHF RFID boleh dipolari atau dipolarisasikan secara linear. Antena polarisasi linear menghantar gelombang frekuensi radio (RF) dalam satah tunggal, yang membolehkan mereka membaca teg yang berorientasikan dengan betul. Antena polarisasi berpola kurang dipengaruhi oleh orientasi tag, tetapi mempunyai jarak maksimum yang lebih pendek.

If you can’t consistently predict the orientation or height of the tag, then a circular antenna will more reliably read your tag, albeit with a shorter range. In the case of the tag on the helmet, we know both the approximate height and orientation of the tag, so a linear antenna gave us the best performance. But given the short distance requirements, both types gave more than satisfactory read range.

polarisasi
Linear vs Antena Polartized Circularly (sumber www.ti.com)

Nombor dan Penempatan: Finally, we need to decide how many antennas are necessary for the job and how to place them at each entry/exit location. As a rough estimate, a circularly polarized antenna covers an 8 foot by 8 foot area at a range of 8 feet from the reader. Figuring out the number of antennas needed then depends the math of your area to cover. More overlap will provide better likelihood of not missing a tag as it passes by. Additionally, the entry and exit antennas needed to be far enough away so that they don’t conflict with each other, but close enough so that no area in the passageway fell out of range. For our scenario, there are 2 drive through portals and 2 walk through portals. For the 10-12 foot wide drive through portals, we used 4 antennas, 2 on each side of the driveway. For the smaller 4-5 foot wide walk through portals, we only needed 2 total antennas, with 1 antenna on each side.

That about wraps it all up! We are very excited about this project and can’t wait to see how much it will improve the everyday lives of the employees who will be using it!

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