The hottest UAV relays RFID signals for inventory

2022-08-23
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UAVs relay RFID signals for inventory control

UAVs relay RFID signals for inventory control

10:44:08 source:

Radio Frequency ID tags should completely change supply chain management. Receiving power wirelessly from the scanner and then broadcasting the identification number is cheap, and the battery free tag enables warehouse managers to record inventory more effectively by reading the box number and manually recording it

but the scale of modern retail business makes even radio frequency ID (RFID) scanning inefficient. For example, Wal Mart reported that it lost $3billion in revenue in 2013 because its inventory records did not match its injection of some clocks and oil depots. Even if RFID technology is used, it may take three months for a large retail store to conduct a complete inventory review, which means that the mismatch is usually undetected before the customer's requirements are exposed

MIT researchers have now developed a system that enables small, safe aerial drones to read RFID tags from tens of meters away and identify the location of tags at the same time, with an average error of about 19 cm. Researchers assume that the system can be used in large warehouses for continuous monitoring to prevent inventory mismatches and the location of individual items, so that employees can quickly and reliably meet customer requirements

the main challenge of designing this system is that under the current autonomous navigation state, the only UAV safe enough to fly in close range is a small light UAV with a plastic rotor. If this happens, they will not cause harm. Collision. But these drones are too small to carry RFID readers with a range of more than a few centimeters

researchers meet this challenge by using drones to transmit signals from standard RFID readers. This not only solves the security problem, but also means that the UAV can be deployed with the existing RFID inventory system without the need for new tags, readers or reader software

between 2003 and 2011, the U.S. Army lost $5.8 billion in supplies in its warehouse. Fadel Adib, an assistant professor of media art and science career development at Sony, said that his team at the MIT Media Laboratory had developed a new system. In 2016, the National Retail Federation reported that items in retail stores reduced losses - an average of about $45.2 billion per year. By enabling UAVs to find and locate objects and equipment, this research will provide basic technological progress to solve these problems

MIT researchers described their system, called rfly, in a paper they presented this week at the annual meeting of the data communications special interest group of the computer association. Adib is the senior author of the paper, and Ma Yunfei, a postdoctoral student in the media laboratory, and Nicholas Selby, a graduate student in mechanical engineering at Massachusetts Institute of technology, also joined him

phase shift

relaying RFID signals and using them to determine the location of tags will bring some thorny signal processing problems. One is that because RFID tags are powered wirelessly by readers, readers and tags transmit at the same frequency at the same time. The relay system adds another pair of simultaneous transmission: two between the relay and the tag, and two between the relay and the reader. These are four simultaneous transmissions of the same frequency, all interfering with each other

the requirement of the system to determine the location of RFID tags makes this problem more complicated. The position detection - or positioning - system uses a variant on a device called an antenna array. If multiple antennas are gathered together, the signals broadcast to them at a certain angle will reach each 1 at a slightly different time Here we choose a 2500n load antenna. This means that the signals detected by the antenna will be slightly out of phase: the troughs and peaks of their electromagnetic waves will not completely coincide. Based on these phase differences, the software can infer the transmission angle, thus inferring the position of the launcher

the UAV is too small to carry the antenna array, but it keeps moving, so the readings at different times are also carried out at different positions, simulating multiple antenna elements of the array

usually, in order to combat interference, UAV will digitally decode the transmission received from the tag and re encode it. Generally, mineral oil with medium viscosity is adopted for transmission to the reader. However, in this case, the delay imposed by the decoding and encoding process will change the relative phase of the signal, making it impossible to measure the position accurately

all radio systems encode information by modulating the basic transmission frequency, usually by moving up and down slightly. However, since RFID tags have no independent power supply, its modulation is detectable less than that of the reader. Therefore, MIT researchers designed an analog filter, which can subtract the basic transmission frequency from the signal arriving at the reader, and then separate the low-frequency and high-frequency components. Then add the low-frequency component - the signal from the tag - back to the fundamental frequency

reference system

however, there is still another problem at this point. As the UAV is moving, the phase shift of the signal reaching the reader comes not only from the position of the UAV relative to the RFID tag, but also from its position relative to the reader. Based on the received signal alone, the reader cannot tell how much each of these two factors contributes to the total phase shift

therefore, MIT researchers also equipped their own RFID tags for each of their UAVs. The drone alternates between forwarding the signal of the reader to the tagged item and simply letting its own tag reflect the signal so that the reader can estimate the contribution of the drone to the total phase shift and remove it

in the experiments involving marking objects in the media laboratory, many of them are deliberately hidden to approach the situation that the success of stacking on the warehouse bench may enhance and encourage the development of goods on shelves in other markets. The system can locate labels with an accuracy of 19 cm, and expand the range of card readers in all directions, or accumulate a hundred times. Researchers are currently conducting a second set of experiments in the warehouse of a large retailer in Massachusetts

relays have been used in communication for a long time, and even brought networks to rural areas, said swarun Kumar, assistant professor of electronic and computer engineering at Carnegie Mellon University. The change here is that one of the ends is battery free. They want to locate and track battery free devices, which requires phase consistent measurement. Together, these make the problem very challenging. This is what I think is the conceptual novelty in this work. I expect there may be more applications than inventory tracking issues - which is very important in itself

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