Help: Sensor needed for very special application:

Setup:

  1. A dark chamber (Hermetically closed).
  2. In the chamber a circular disc is mounted on an electric motor. The disc is mounted horizontally in the chamber.
  3. The diameter of the disc is 2 meters (2 yards).
  4. Now the disc runs at about 25 rpm and a mix of sand and rocks is poured on the table.
  5. Due to centrifugal forces the sand/rock mixture starts to move outwards.
  6. While running there is also a dust/sandstorm present inside the chamber. The dust/sandstorm is so severe that one cannot see a hand in front of himself (with a torch).

Under those conditions I want to be able to measure the sand/rock flow on the table. I want to see what happens when and how the sand/rocks move towards the edge of the disc. I want to see how fast, I want to see if anything builds up etc etc. The perfect thing would be to install a video camera inside the chamber but due to the sandstorm this is virtually impossible to my opinion. Are there any sensors available giving a hight profile as an output? What about doppler, ultrasound, infrared and so on? What is the most promising sensor solution for this project?

To me, this sensor looks very interesting:

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...but I'm afraid that this wont work because the laser light wont be able to penetrate my sandstorm.

Do you experts have any solutions for my problem?

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After measuring the material flow on the table, I need to measure how the particles move in the sandstorm - more precisely in what direction they are moving and at what velocities. What sensors would be suitable for that task?

PS: All sorts of equipment can be installed inside the chamber, such as flourescent light, regular light etc etc.

Thank you in advance, L. Jensen

Reply to
BikeManiac
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Ultrasound is probably your best bet. I envision some form of side scan sonar like used to visulize the sea floor, etc. It sends out an ultrasonic pulse directed at an angle to the rotating disk then listens for recived reflections off of the disk. The arival time of the reflected waves is proportional to the distance of the reflection from the disk thus forming a scan. The fine scale time variations are used to image the shapes of objects on the disk Doppler can be used to determine if there is relative motion of the objects. The scan is repeated many times per second to build of an image of objects on the disk as it rotates. Several of these side scan units could be employed around the disk to enhance the image of the detected objects and to determine how things moved with rotation angle. This would require a fair degree of digital image processing, but I think, is doable. Needless to say you are probably not going to find a ready made, off the shelf hardware and software to do this. Be prepared to spend some bucks. Bob

Reply to
Bob Eld

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