403047_Chapter 2. Characteristics and Error Analysis of Measuring system.pptx

TÀI LIỆU

1. Process control: 403047 CHAPTER 2: CHARACTERISTICS AND ERROR ANALYSIS OF MEASURING SYSTEM Dung Nguyen Quang, MSc. Ton Duc Thang University Faculty of Electrical and Electronics Engineering 11/21/2016 403047- Chapter 2: Characteristics and error analysis of measuring system

2. OBJECTIVES Static characteristics of measurement: error, accuracy, sensitivity, reproducibility and dead zone Dynamic characteristics of measurement. Error analysis of measuring systems: errors, statistical treatment of data, and single-sample and multi-sample tests. Transducers. 403047- Chapter 2: Characteristics and error analysis of measuring system Students will understand: 11/21/2016 2

3. CONTENT OF CHAPTER 2 2 .1 . Static characteristics 2 .2 . Dynamic characteristics 2 .3 . Error analysis of measuring systems 11/21/2016 403047- Chapter 2: Characteristics and error analysis of measuring system 3

4. STATIC CHARACTERISTICS Characteristics of the measuring system which do not change with time, are know as static characteristics. Static characteristics are: Errors Accuracy Sensitivity Reproducibility Dead zone 403047- Chapter 2: Characteristics and error analysis of measuring system 11/21/2016 4

5. STATIC CHARACTERISTICS 1. Error where are the indicated and actual values. 2. Accuracy where (A and B are multiplicative and additive corrections)   403047- Chapter 2: Characteristics and error analysis of measuring system 11/21/2016 5

6. STATIC CHARACTERISTICS 3. Sensitivity Sensitivity is expressed as the ratio of the magnitude of the output to the magnitude of the input signal.   403047- Chapter 2: Characteristics and error analysis of measuring system 11/21/2016 6

7. STATIC CHARACTERISTICS 4. Drift: Drift causes the measurement result to vary for a given value 403047- Chapter 2: Characteristics and error analysis of measuring system 11/21/2016 7

8. STATIC CHARACTERISTICS 403047- Chapter 2: Characteristics and error analysis of measuring system 5. Dead zone Dead zone is the largest change in input quantity for which a noticeable change in output quantity. 11/21/2016 8

9. DYNAMIC CHARACTERISTICS The dynamic characteristics of a measuring system vary over time. Characteristics are classified in to following categories: Steady-state periodic Transient 403047- Chapter 2: Characteristics and error analysis of measuring system 11/21/2016 9

10. ERROR ANALYSIS 403047- Chapter 2: Characteristics and error analysis of measuring system The accuracy and precision of a measuring instrument depend upon its design and individual parts, and the quality of manufacturing. 11/21/2016 10

11. CLASSIFICATION OF ERRORS Errors can be classified: Systematic errors Random errors Illegitimate errors. 403047- Chapter 2: Characteristics and error analysis of measuring system 11/21/2016 11

12. CLASSIFICATION OF ERRORS 1. Systematic errors are due to faulty or improperly calibrated instrument. Sources of systematic errors: Calibration errors Human errors Experimental errors Loading errors 403047- Chapter 2: Characteristics and error analysis of measuring system 11/21/2016 12

13. CLASSIFICATION OF ERRORS 2. Random errors result from friction in an instrument, backlash in the movement of the indicator, hysteresis in elastic members. Sources of random errors: Errors owing to different experimental conditions Parallax errors. 403047- Chapter 2: Characteristics and error analysis of measuring system 11/21/2016 13

14. CLASSIFICATION OF ERRORS 3. Illegitimate errors occur on account of blunders or mistakes in the measurement process. Sources of illegitimate errors: Blunders or mistakes Computational errors Chaotic errors 403047- Chapter 2: Characteristics and error analysis of measuring system 11/21/2016 14

15. STATISTICAL TREATMENT OF DATA Data It is the numerical information obtained by experimental means. Population It is a set of data. Sampl e It is a part of the population 403047- Chapter 2: Characteristics and error analysis of measuring system 11/21/2016 15

16. STATISTICAL TREATMENT OF DATA True value ( Va ): Actual magnitude of an input signal. Indicated value (Vi): the magnitude of a variable indicated by measuring instrument. Result ( Vr ): where A, B are multiplicative and additive corrections, respectively. Errors : Accuracy :   403047- Chapter 2: Characteristics and error analysis of measuring system 11/21/2016 16

17. STATISTICAL TREATMENT OF DATA Precision is the degree of agreement between repeated results. 403047- Chapter 2: Characteristics and error analysis of measuring system Mean: Deviation : Standard deviation:   11/21/2016 17

18. BASIC TRANSDUCER A transducer is a device that converts physic signal into electrical signal. 403047- Chapter 2: Characteristics and error analysis of measuring system 11/21/2016 18

19. BASIC TRANSDUCER Requirements of transducers: Small size Low weight High reliability High sensitivity Ability to withstand environmental changes Linear relationship between input and output Low cost. 403047- Chapter 2: Characteristics and error analysis of measuring system 11/21/2016 19

20. SUMMARY In this chapter we have learnt: Characteristics of measurement Errors analysis Transducers. 403047- Chapter 2: Characteristics and error analysis of measuring system 11/21/2016 20

21. ASSIGNMENTS Reading [1]: 13-61; [2]: 78-83 . Doing [1]: review questions 1-11. Doing [1]: objective type questions 1-12. 403047- Chapter 2: Characteristics and error analysis of measuring system 11/21/2016 21