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A force-torque transducer data acquisition system is shown below:

enter image description here

As shown in the above illustration, basically a six-axis transducer is powered and amplified by an interface electronics and then the differential ended output voltages are coupled to a data acquisition hardware to be processes by a PC.

Some civil/mechanical engineers mount a model on the top of the transducer and apply wind to analyse vibrations. They rotate the model and apply wind to measure vibrations for different angles.

Recently they have been telling that, when they take offset(no wind condition) during the measurements they observe drift. I first thought it could be the excitation voltage but then I know the voltage inside the electronic interface is very stable. The drift is observed during an offset measurement. I also have been told that the temperature is not changing during the 1 minute offset. So drift most probably is not due to the temperature of power supply.

In the manual here there is a section about drift and hysteresis:

enter image description here

I have never heard something called "mechanical coupling" and in this case I don't understand what they mean by:

Make sure the tool and tool adapter plate and the transducer body are isolated from each other

I don't know the amount of drift at the moment and for now I suggested them to wait for the drift to settle and then take measurements. But soon I have to go to investigate about these.

What can be done as a procedure to verify the root cause of the drift in this case? And what is meant by "mechanical coupling" and isolation in the manual?

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Mechanical coupling means some mechanical connection between parts of the system. In this case the trouble-shooting guide is advising you to check for mechanical coupling or connection where there shouldn't be any - especially "between the tool-plate and the sensor body". This would be equivalent to having enough debris inside your bathroom weigh scales to affect the reading in certain situations - maybe above a certain weight.

Since the device is designed to be sensitive to wind I would shield it, monitor the excitation voltage, temperature and any other variables you can think of while logging the output. Check for mechanical stability, debris, loose mechanical connections, etc.

If all of that looks OK then you may have an electronic failure. If you're going to open it up have a look for leaky or bulging electrolytic capacitors.

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  • \$\begingroup\$ "some mechanical connection between parts of the system" Without any mechanical connection how can the system move? I still dont get what is meant by this. \$\endgroup\$ – user1999 Apr 22 '18 at 17:52
  • \$\begingroup\$ What can that to do with drift also blur for me. \$\endgroup\$ – user1999 Apr 22 '18 at 17:55
  • \$\begingroup\$ If I remove the model and use only transducer and observe no drift does that mean the issue is mechanical at least? \$\endgroup\$ – user1999 Apr 22 '18 at 17:58
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    \$\begingroup\$ I don't know but the manufacturers may have come across something if it's in the trouble-shooting guide. Maybe something jammed in the gap between the plate and the chassis that deforms slowly. You haven't given a make, model, link to datasheet or any explanation of the sensor type so all we can do is guess. \$\endgroup\$ – Transistor Apr 22 '18 at 18:00
  • \$\begingroup\$ I will try to update after I try your suggestions. It might take some days to update. Thanks \$\endgroup\$ – user1999 Apr 22 '18 at 18:49

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