| General > General Technical Chat |
| Laser Needle Controller/Sensor, Working Principles. |
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| palpurul:
Hello, Recently I visited a small knitting factory with about 20 circular knitting machines. They were pretty rudimentary. I talked to the owner of this factory to understand what they need to improve their manufacturing. He constantly talked about the needle controller/sensors, how useful it can be if they were to integrate them into each machine in the factory. There are a few companies selling them, but apparently the price is a bit prohibitive. I thought this can be a good opportunity for me because there are many small knitting factories in my city, and I decided to research more about it. Needle controllers/sensors are basically checks if there are any missing or bent needles in the knitting machine. I've found a video showing how it works, it's a very short video: How do you think it works? what kind of Lasers they are using to detect broken needles? It seems like they implement kind of a TOF algorithm, but I am not sure and came here to ask for opinions on how these devices work. The algorithm to detect broken needles must be kind of complicated, as of right now I can't wrap my head around it because knitting machines can rotate at not constant but variable speeds they are not very repeatable in terms of their operation. I just need to brainstorm more I guess. :-// These are a few devices on the market: https://www.protechna.de/en/rundstrickmaschinen/needle_sensor_4022 https://www.memminger-iro.de/en/ueberwachung/mnc2.php |
| MegaVolt:
Camcorder / camera + digital processing. Comparing the pictures with the correct ones? |
| palpurul:
--- Quote from: MegaVolt on March 02, 2022, 09:45:35 am ---Camcorder / camera + digital processing. Comparing the pictures with the correct ones? --- End quote --- I don't think so. The video shows some type of laser is being used and I don't think it can be done with a camera becuase needles move pretty fast, well at least you can't do it affordably you'd need a pretty fast camera. |
| PlainName:
Isn't it just a missing pulse detector? The laser bounce triggers the detector and then it's just checking the next one comes in at the expected time. Where you might have deliberately missing needles (don't know if they do, but I imagine there's a use case for that) the device knows when a gap should appear and it would be regular, so that's not a big problem. As for variable speed, either the needle transfer gubbins tells you what speed it's running at or you extrapolate from the timing between hits. Am I missing something? |
| palpurul:
--- Quote from: dunkemhigh on March 02, 2022, 11:28:02 am ---Isn't it just a missing pulse detector? The laser bounce triggers the detector and then it's just checking the next one comes in at the expected time. Where you might have deliberately missing needles (don't know if they do, but I imagine there's a use case for that) the device knows when a gap should appear and it would be regular, so that's not a big problem. As for variable speed, either the needle transfer gubbins tells you what speed it's running at or you extrapolate from the timing between hits. Am I missing something? --- End quote --- I think it's just a more sophiticated version of a missing pulse detector. They have intentionally omit a few needles, so the device needs to be aware of this as well. Extrapolating part kind of confuses me, but I think we can easily measure the rpm of the needle spinner, that way we can roughly estimate the time between each needle. I am not too familiar with missing pulse detectors, do you have any resource that you can recommend about it? |
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