RFID Basics – Gain Key Knowledge to Select the Best Fit System

As digitalization evolves, industrial companies are automating more and more manual processes. Consequently, they transfer paper-based tasks in the field of identification  to digital solutions. One important enabling technology is radio frequency identification (RFID), which uses radio frequency to exchange data between two different entities for the purpose of identification. Since this technology is mature, many companies now trust it to improve their efficiency. Strong arguments for RFID technology include its contactless reading, which makes it wear-free. Plus, it’s maintenance-free and insensitive to dirt.

RFID basics for selecting the best fit system

There are myriad applications for RFID in the manufacturing process, which can be clustered into the following areas:

    • Asset management e.g. tool identification on machine tools or mold management on injection molding machines in plastic processing companies
    • Traceability for work piece tracking in production
    • Access control for safety and security purposes by instructed and authorized experts to ensure that only the right people can access the machine and change parameters, etc.

But not all RFID is the same. It is important to select the system type and components that are best suited for your application.

Frequencies and their best applications

RFID runs on three different frequency bands, each of which has its advantages and disadvantages.

Low Frequency (LF)
LF systems are in the range of 30…300 kHz and are best suited for close range and for difficult conditions, such as metallic surroundings. Therefore, they fit perfectly in tool identification applications, such as in machine tools, Additionally, they are used in livestock and other animal tracking. The semiconductor industry (front end) relies on this frequency (134kHz) as well.

High Frequency (HF)
HF in the range of 3…30 MHz is ideal for parts tracking at close range up to 400 mm. With HF you can process and store larger quantities of data, which is helpful for tracking and tracing workpieces in industrial applications. But companies also use it for production control. It comes along with high data transmission speeds. Accordingly, it accelerates identification processes.

Ultra High Frequency (UHF)
UHF systems in the range of  300 MHz…3 GHz are widely used in intralogistics applications and typically communicate at a range of up to 6 m distance. Importantly, they allow bulk reading of tags.

RFID key components

Every RFID system consists of three components.

    1. RFID tag (data carrier). The data carrier stores all kinds of information. It can be read and/or changed (write) by computers or automation systems. Read/write versions are available in various memory capacities and with various storage mechanisms. RFID tags are usually classified based on their modes of power supply, including:

– Passive data carriers: without power supply
– Active data carriers: with power supply

2. Antenna or Read/Write head. The antenna supplies the RFID tag with power and reads the data. If desired, it can also write new data on it.

3. Processing unit. The processing unit is used for signal processing and preparation. It typically includes an integrated interface for connecting to the controller or the PC system.

RFID systems are designed for some of the toughest environments and address just most identification applications in the plants. To learn more about industrial RFID applications and components visit www.balluff.us/rifd.

Solar tracking systems and sensors

Over the last few years there has been a lot of discussion on how we will meet the global energy demand in the future. And what will be the technologies to generate it? In the end it all comes down to the levelized cost of electricity (LCOE), which is the sum of all costs of a power plant divided by the total electricity that is generated over the plant’s lifetime. All companies in the renewable energy industry focus on reaching lower LCOE compared to conventional power generation (especially gas). Their biggest advantage is that there are no costs for fuel (sun light, wind, water).

solarpanelsLet’s take solar power as an example. Principally there are two ways to use the sun light: First it can be converted directly to electricity (photovoltaics). Second, it can be used indirectly by generating thermal energy (concentrated solar power). In order to reach higher efficiency solar trackers are used to orient photovoltaic panels, reflectors, or mirror towards the sun. On the other hand they add costs to the system. Therefore it must be carefully calculated whether a tracker (single or dual axis) is required or not (fixed installation).

solarpanels2Single axis trackers are used to position photovoltaic panels, parabolic troughs or linear Fresnel collectors from east to west on a north to south orientation. Depending on the required tracking accuracy different sensors are used for this task. As most of the photovoltaic trackers use electric linear actuators, very often inductive sensors are installed on the actuator for position feedback. They are cost optimized and are a standard feature in the actuators. Another option is to use inclination sensors that are directly mounted on the rotating shaft to provide angle feedback (e.g. in linear Fresnel plants). As inclinometers are mounted on the moving part, there is cable wear that could lead to failure over time. For high end tracking, as is required in parabolic trough plants, magnetic tape systems are used as rotary encoders. A magnetic tape is mounted around the shaft and a sensor head is installed on the frame of the tracker. The sensor counts the pulses accurately and provides continuous position feedback without any wear.

solarpanels3Dual axis trackers are used to position concentrated photovoltaic (CPV) panels, parabolic reflectors (dish) or mirrors (heliostats). Especially in central receiver plants high accuracy is required. They need high temperatures and therefore have to focus lots of light on a central receiver on top of a tower in the middle of the heliostat field. As there is an azimuth and an elevation axis, two position feedback systems are required. The elevation angle could be solved with an inclinometer, but this does not work for the azimuth position.  Again, the position could be measured with embedded rotary encoders directly on the drive. But there is again backlash, and accuracy is of highest importance as heliostats could be one mile away from the central receiver. Magnetically coded position and angle measurement systems can be mounted on both axis (azimuth and elevation) and provide direct position feedback with highest accuracy.

More information can be found in this brochure about power generation. http://asset.balluff.com/std.lang.all/pdf/binary/861522_162563_1305_en-US.pdf

Special thank you to Bernd Schneider, Industry Manger – Balluff GmbH for contributing to this post.