distinguish between accuracy and precision
Answers
Explanation:
Accuracy and precision are different aspects related to obtaining a correct measurement. Accuracy is related to how close to the real value a particular measurement (or set of measurements) is. Precision is how small a difference can be resolved and how repeatable a measurement is.
Explanation:
ACCURACY:-
- Accuracy is a term used to describe the difference between target position and actual position. Encoder accuracy is specified in degrees, arcminutes or arcseconds.
- Within the encoder itself, accuracy can be affected by several variables.
- Imaging: location of the lines on the disk must be exact, or accuracy will suffer
- Installation: mounting an encoder hubdisk off center on the shaft can decrease accuracy
- Size: an encoder with a larger disk will be more accurate than one with a smaller disk
External to the encoder, other mechanical parts of the application affect system accuracy. Gear backlash, leadscrews, shaft and bearing play can add up and have much more of an effect than the encoder's accuracy contribution.
PRECISION:-
Precision is a term that describes repeatability. It's the amount that successive measurements at the same location differ from each other. If an encoder is off by 2 degrees at a particular position, but it is always off by the same 2 degrees at that location, then the encoder has good precision.
Most encoders are reasonably accurate and precise. Of the three terms we've discussed, people are usually most concerned with resolution, then accuracy, and finally precision. Encoders provide the resolution, with the number of lines on their optical components (disk and sensor); accuracy is related to alignments in the mechanical system that affect the encoder; and precision can be a product of either—or probably both. Josh from Tech Support says that issues about precision rarely come up when people call.