Synchronization of a camera with a rotating shaft

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Discussion Overview

The discussion revolves around the synchronization of a thermal camera (FLIR A300/600) with a rotating shaft to automatically capture images when the shaft section is orthogonal to the camera's line of sight. Participants explore the feasibility of using a proximity sensor for triggering the camera and discuss various technical considerations related to the setup.

Discussion Character

  • Technical explanation
  • Exploratory
  • Debate/contested

Main Points Raised

  • One participant suggests using a proximity sensor that outputs a TTL pulse to trigger the camera when the test section is detected.
  • Another participant emphasizes the importance of verifying that the sensor can handle the rotational speed of the shaft, noting that different speeds may require adjustments in sensor placement due to potential delays in image capture.
  • A participant raises concerns about the speed of the camera, mentioning that microbolometer arrays may not respond quickly enough to capture details of a rapidly spinning shaft.
  • There is a suggestion to consider using hall effect sensors if a magnet can be attached to the shaft.
  • Some participants discuss the exposure time required by cameras and how it affects the ability to capture images of fast-moving objects.
  • One participant questions the necessity of an op-amp in the proposed circuit, suggesting that the output from an AND gate may suffice for the camera's TTL input.

Areas of Agreement / Disagreement

Participants express varying opinions on the effectiveness of different sensor types and the impact of camera response times. There is no consensus on the best approach, and multiple competing views remain regarding the synchronization setup.

Contextual Notes

Participants note potential limitations related to the speed of the camera and the rotational speed of the shaft, as well as the need for careful consideration of timing and sensor placement. The discussion does not resolve these issues.

ishaan
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I wish to synchronize a thermal camera FLIR A300/600 with a test section on a rotating shaft such that whenever the section becomes orthogonal to the line of sight of the camera, an image is clicked by it automatically. The camera uses a TTL pulse input. Being a mechanical engineer, I have little idea as to the electrical components involved. However, I have thought of placing a proximity sensor on the mutually orthogonal axis in front of the section, such that whenever it detects an obstacle(the test section), a pulse is sent to the camera. I wish to confirm whether this will work before actually implementing it on the expensive camera. Also, if someone has used a similar setup can guide me as to what all settings are needed in camera software and whether the pulse output by proximity sensor(PNP) is in compliance with the camera.
 
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ishaan said:
I wish to synchronize a thermal camera FLIR A300/600 with a test section on a rotating shaft such that whenever the section becomes orthogonal to the line of sight of the camera, an image is clicked by it automatically. The camera uses a TTL pulse input. Being a mechanical engineer, I have little idea as to the electrical components involved. However, I have thought of placing a proximity sensor on the mutually orthogonal axis in front of the section, such that whenever it detects an obstacle(the test section), a pulse is sent to the camera. I wish to confirm whether this will work before actually implementing it on the expensive camera. Also, if someone has used a similar setup can guide me as to what all settings are needed in camera software and whether the pulse output by proximity sensor(PNP) is in compliance with the camera.

Welcome to the PF.

You should be able to find a proximity sensor that outputs a TTL pulse. You can use some of those words in a Google search to see what pops up. I like to use Google Images for an initial search for things like sensors, since you can scan the results visually much faster than clicking into a bunch of links from the search.

Can you attach a picture or two (or link to them if you have them on a hosted website)? It would help to see what you are working with... :smile:
 
Image

Here's a rough sketch of the circuit I am hoping to use
 

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I have not used proximity sensors in a long time. But since you did not mention it, you need to verify that the speed of rotation of the shaft will work for the sensor chosen. Most shaft encoders use optics with a disk on the shaft which has window openings, in your case only 1 would be necessary. Then you might have to advance your sensor location (whatever type is used) because of any delay in the image capture from the pulse. This could be dependent on the speed of the shaft depending on the speeds involved. Big difference between 300 rpm and 10,000 rpm in sensing and capture. So if you are looking at covering a wide range of rotational speeds, you might need something to adjust the timing.
 
ishaan said:
Here's a rough sketch of the circuit I am hoping to use

I don't see any need for the opamp. The output of the AND gate should be sufficient to drive the TTL input of the camera.
 
One thing that needs to be considered is the speed of the camera. The models cited use microbolometer arrays which are not all that fast to respond to temperature changes. A spinning shaft may be a bit too fast for them to capture in any detail.
 
You might want to consider hall effect sensors if you can attach a magnet to the shaft.
 
Ryoko said:
One thing that needs to be considered is the speed of the camera. The models cited use microbolometer arrays which are not all that fast to respond to temperature changes. A spinning shaft may be a bit too fast for them to capture in any detail.

I agree. All cameras require exposure time to capture photons. And each pixel on the sensor may have different timing.
 
Viggo said:
I agree. All cameras require exposure time to capture photons. And each pixel on the sensor may have different timing.

It's not so much that each pixel might have different timing, but rather that microbolometers are in essence tiny thermometers and like thermometers, they don't respond instantly. So a spinning shaft will likely be seen as just a blur even if the camera is timed correctly.