Potentiometers

[tsaksa]

Our team did not use potentiometers this year mostly due to bad experiences last year. I was not on the team at the time, so I do not know the details, but potentiometers can cause trouble in some designs, but can also be a effective position sensor if you know both their capabilities and limitations.

Potentiometers are (mostly) mechanical devices. They produce an absolute position signal rather than incremental, but often at a lower resolution than many encoders. They also produce an analog output, and can be noisy particularly with lower cost potentiometers so using them sometimes requires filtering either in hardware or software which can make them too slow for some applications. And the dead band region is an issue for continuous motion unless you find a way to mount two of them together with enough overlap in the signals so that your software can account for this.

As with any sensor, there are advantages and disadvantages and experience with them will help you pick the best places to use them and also to work around the disadvantages. Like I said, our team had a bad experience with them and want to avoid them. My response was not to push for them to be used during this build season. But I will want the electrical and software team to get some experience with them in the off season and gain some understanding of them so any future decision on using them is based on real data.

Good luck with your application, and take some time to think specifically about what you really need to measure. How accurate does the measurement need to be, how quickly does the data need to be updated, can you tolerate some noise or dead spots? This is some real systems engineering. I believe that selecting the correct sensors for various parts of a system is often not given enough consideration. But, how well a system works when complete is often highly dependent on these choices.