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Topic: rotary torque sensor (Read 23732 times) previous topic - next topic


I have read through this topic and I also am faced with a problem.

Just to paint a picture. I am a fourth year mechanical engineering student from Stellenbosch University (South Africa). I am busy with my final year project which is as follows: "Develop a system to measure the torque on the shaft of a turbocharger".

While in essence it doesn't sound to hard, there are quite a few obstacles. Firstly the systems sound preferably work up to 30 000 rpm which eliminate using slip rings or any contact system. Secondly there isn't much free space on an assembled turbocharger for mounting any systems.

For this reason I have simplified the system by not going up to 30 000 rpm but maybe near 3000 rpm. Also I am going to have my own shaft machined and fitted with the compressor and turbine from and existing turbocharger.

So after all of this I actually need to get to my questions. I thought of using to gap sensors (or optical encoders), one of each end of the shaft, then by measuring the difference in time that it takes for each sensor to get a reading and having the rotational speed, one can determine the torsion angle of the shaft.

In theory this seems to be a viable option. Does anyone have any advice for me on how to do this. I do not have much programming skill and really want to use an arduino. so I need info on how fast arduinos can log data and what the max interrupt speed of and arduino is. Also what functions should I used to log the time at which the arduino receives the sensed information?

If anyone has any advice I would deeply appreciate it.



The shaft has to be slender to allow significant twisting at the torque levels used, which of course
adds elasticity in the system, which may have consequences.  But it also has not to break or whip!

I suspect metal is a poor choice, perhaps delrin is a reasonable material - machinable, much lower
modulus, so can be a more reasonable proportions.  However turbines run hot, so this may be

Another approach would be some sort of torsional spring arrangement joining the shaft ends.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]


we need some either pics or drawings


Sorry to grave dig.
Could you not use a liner effect?
Have a shaft off the rear of the motor through a bearing and out to a second bearing a specific distance on a swivel; then measure the length from the motor to the end of the shaft?


Hey. I'm going through exact the same situation here.

Have you got any solution for measuring rotary torque with a gap sensor or an optical encoder? Or did got follow any other method for measuring this?

Looking forward to your reply/suggestion.


one of my friends has gone through a similar problem with the usage of the rotary shaft to shaft torque sensor. He used strain gauge instead of the rotatory shaft. With strain gauges bonded to the shaft, the shaft becomes the transducer. Secondly, the shaft to be calibrated, a process that usually involves loading the shaft statically and tabulating the results. This is relatively easy to do in small systems, but as loads and shaft size increase, it becomes an onerous task. Selecting a location for the strain gauges, mounting them carefully and protecting them become problematic for users inexperienced in such techniques. Outside contractors are usually available through the torque sensor suppliers for most applications and locations.
Thank You.



I have same problem, too. Anybody is solved these?

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