Cloth Level Detection

Make the free spreading cloth into a crushed and compressed self pressed and tied ball, so that it can get fully seated on the pan.

*SImple common sense solution, try if it works. See that it does not touch the walls or sides.

You can also use pre measured strings for balling the fabric, load it on the pan and finally deduct the string's weight.

Not possible, this system is like a central vacuum system with many inlets, collecting clothing to be washed. Bin collects X amount of clothing then dumps it to a wash machine.

Check the performance characteristics of some capacitive prox's or maybe sonic.

Will capacitive prox solution not be absorbed by the cloth?

I have heard may places that sonic is useless in this type of application.

Ultrasonics are used in a wide variety of level sensing from water to paper. Once they are set they are reliable. Granted they are not tampered with. You can have the 4-20ma output and depending on the sensor, you can have multiple switch points.

Try isolating the bin from the vacuum system using flex hose so that the suction (lift?) does not affect the apparent weighton the load cells. Or, turn off the vacuum when you weigh.

We are already on a flex collar, and we have added extra weight to the bin of around 175 pounds to try to break free of the lift caused by the vacuum. None of that worked and to add more weight, we would have to re-design our structure holding the bin up. Not an option at this point, machine is in production.

I'm not quite sure where and how the vacuum is applied in this situation, but ultrasonics do not work in vacuum.

The 'sonics' part of ultrasonics refers to energy transmitted through a gaseous atmosphere, like air, at frequencies above those humans can hear. In short, no atmosphere, no transmission of 'sonic' energy.

Ultrasonic level probes could work here because it is not a complete vacuum, just a lower air pressure and that could be compensated for. The bigger problem for ultrasonics could be that the fabric lies loose and random and so does not reflect back enough sound to provide a reading, similar to the way stealth fighters deflect radar.

You could try measuring the weight of the bin with it empty and the vacuum on and use this as your empty (tare) weight.

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Ultrasonic level probes could work here because it is not a complete vacuum, just a lower air pressure and that could be compensated for. The bigger problem for ultrasonics could be that the fabric lies loose and random and so does not reflect back enough sound to provide a reading, similar to the way stealth fighters deflect radar.

You could try measuring the weight of the bin with it empty and the vacuum on and use this as your empty (tare) weight.

Well since there seems to be an over abundant of un-employed workers ( est. 17% ), you can pay them piece work to catch the clothes!

Other than doing some engineering to use the right sensors, I'm at a loss.