This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: 06-1 06-1 Error Error is the difference between an ideal (or correct) value and an actual value. Several different types of error can be measured. An error type can be expressed in several ways. 06-1 EE 4770 Lecture Transparency. Formatted 8:29, 25 January 1999 from lsli06. 06-1 06-2 06-2 Expression of Error Notation I denotes an ideal value . A denotes an actual value. Absolute error defined |I - A| . Percent error defined 100 |I - A| I for I 6 = 0. Consider a transducer designed to measure process variables in the range I [ x min , x max ]. Percent-full-scale error defined 100 |I - A| x max for x max 6 = 0. 06-2 EE 4770 Lecture Transparency. Formatted 8:29, 25 January 1999 from lsli06. 06-2 06-3 06-3 Types of Error Model Error. Error in transducer model, H t . Repeatability Error. Transducer change from occasion to occasion. Stability Error. Transducer change during use. Calibration Error. Difference between two transducers of same kind. 06-3 EE 4770 Lecture Transparency. Formatted 8:29, 25 January 1999 from lsli06. 06-3 06-4 06-4 Model Error Let y = H t ( x ) denote a transducer output, response, and process variable. The accuracy of H t ( x ) depends upon how well the transducer is understood and how complex a transfer function can be tolerated. For example, the following are all for the same transducer: Okay: H t1 ( x ) = R o (1 + ax ). Good: H t2 ( x ) = R o (1 + ax + bx 2 ). Better: H t3 ( x ) = R o (1 + ax + bx 2 + cx 3 )....
View Full Document
- Fall '99