Sensor to detect a fast moving plastic bar of 1mm diameter

Other Hardware Sensors
21

Your call. But the more information you give, the better advice you get.

For example: what is the purpose of detecting these flying strings? Maybe there is a better way to achieve that purpose. But if we don’t know...

22

I tried with this one and is worst than the ultrasonic HC-SR04.

23

OK, I try to tell what I can.

I have a plastic tube/wire of 1mm diameter that is fixed one end and flexible at the other. At some point the tube will start move suddenly in the flexible end (for example from the wind).
I want to detect when the flexible end starts moving.

I mention that:

  • it cannot be in touch with other object to trigger the start of the movement (the flexible end should be free and not touching anything)

  • I cannot attach anything to the bar

  • detection should be only from one side (cannot use a sensor like laser module KY-008 which has 2 parts; 1 part laser and 2nd part laser receiver).

I was thinking that putting a sensor near the flexible end of tube will detect/trigger when it starts moving.
I tried with ultrasonic HC-SR04 but not detecting so thin tube, only starting with 2mm diameter as I tested.

That's why I asked maybe for some other ideas.

24

Can you attach the fixed end to whatever is supporting it using a bend sensor or something else that could detect that there is an applied force?

25

That's helpful.

Please post a photo, too. Cut/paste a screenshot works fine. That should answer a lot of questions.

Also...

  • So there's going to be just one string moving around in the breeze?

  • How will the string be suspended so it is only 2 to 4 cm above the sensor?

  • And you want to detect every time it crosses the sensor field of view?

  • The uncertainty about speed is because you don't know how fast the wind will move it?

  • What is the purpose of detecting string crossings? What will you do with the triggers?

26

Could you used compressed air through the tube and detect the air flow at a sensor near the end of the tube? Air pressure equals no movement. Sudden change in pressure equals movement.

27

Nice outside the box thinking.. :+1: :+1:

Tom.. :smiley: :+1: :coffee: :australia:

28

Nice solution Tom, but unfortunately I cannot attach anything to to bar. Thanks a lot, like your post.

29

Hi everyone,
I found a sensor that has a detection accuracy of 1mm https://www.aliexpress.com/i/33008144645.html
As I found on the internet, the US-026 is an upgraded version of the HC-SR04, with a kind of high performance..
I ordered it and wait to test it. I will come back after the tests to let you know, but will take a bit of time until it will arrive.
Until than all the best.

30

LIDAR would do the job. The LIDAR on the ground measuring distance and when the distance is at its shortest, say 3mm or so depending upon the mounting of the LIDAR, that's when the jump rope is overhead.

31

Then go one step further and use the END of the tube/rod as a light reflector. If the end is cut smooth as glass, the surface will be a light reflector. Use an IR light/detector to see the reflection.

32

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