Hello, everyone:

I have discussed with some colleagues about which is the correct criteria or method to calculate the hysteresis error. I will use as an example a humidity sensor VS output (V) with two (02) up-down cycles. I will attach some figures for better understanding.

CRITERIA 1
1.1: Calculate hysteresis for each input value as an absolute value between each pair up-down for each cycle. I will explain this point later on.
1.2: Calculate the average hysteresis for each input value.
1.3: Maximum average hysteresis is the hysteresis error.



CRITERIA 2
2.1: Calculate the average "UP" and the average "DOWN" values for each input.
2.2: Calculate the difference between average values.
2.3: Maximum difference value is the hysteresis error.



I do not agree with the CRITERIA 2 as it consideres negative values with positive ones without any absolute values. Therefore, negative errors "cancel" the positive ones.

In fact, by using the CRITERIA 2 with other data within the column "DOWN 2" in such a way it appears the same average "UPs" and "DOWNs", it would obtain hysteresis equals to CERO... it makes no sense because if those cycles are graphed, both show hysteresis error.





Due to aforementioned discussion, I think the correct method is the CRITERIA 1 as it considers the hysteresis error as an absolute value for each input and each cycle.

I would appreciate your comments in this regard.

Thank you and regards,

Jaime

 

You need to explain how the individual tests are performed, and what standard is used to guage calibration error, before attempting to address hysteresis.

 

Fundamental to establishing "hysterisis" you need to clarify the deadband error in your measurments

 

Fundamental to establishing "hysterisis" you need to clarify the deadband error in your measurments

Please, do consider the deadband error is already subtracted.

 

If it is only an example, there are countless references to address accurracy and the various subcategories involved. You'll be better off sorting out what works in your case. It won't be simple as there are eighteen categories for static error, and that's just the beginning.

Good luck,

 

If you are dealing with process control, as you summary of valve errors suggest you might be, it is far more complicated.