Research Papers

Application of dc Servomotor on Airflow Measurement

[+] Author and Article Information
Thananchai Leephakpreeda

School of Manufacturing Systems and Mechanical Engineering, Sirindhorn International Institute of Technology, Thammasat University, P.O. Box 22, Thammasat-Rangsit Post Office, Pathum Thani 12121, Thailandthanan@siit.tu.ac.th

J. Dyn. Sys., Meas., Control 132(2), 021004 (Feb 02, 2010) (7 pages) doi:10.1115/1.4000813 History: Received May 28, 2008; Revised November 14, 2009; Published February 02, 2010; Online February 02, 2010

The aim of this research paper is to systematically present an optimal control of a dc servomotor for the airflow measurement in both the magnitude and the direction. During measuring airflow, the dc servomotor drives a paddle around the rotor axis in a field. The torsional load of the dc servomotor is caused from resistance of the airflow over the moving paddle normal to the flow. The variations on the torsional load in one revolution of rotation can be characterized from the magnitude and direction of the airflow. In other words, the magnitude and direction of airflow cause a periodic function of the torsional load with respect to the angular position of the paddle. By using Fourier analysis, it is found that the magnitude and direction of the airflow can be determined from the coefficients of the Fourier series. Typically, the torsional load of the dc servomotor, unlike the rotor speed, cannot be measured by the built-in device. In this work, it is determined by applying the extended Luenberger observer method. A state-feedback controller with the observer based on H2 control design is implemented to regulate the dc servomotor. The experimental results on the measurement of airflow show the viability of the proposed methodology.

Copyright © 2010 by American Society of Mechanical Engineers
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Figure 1

Diagram of airflow measurement via dc servomotor

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Figure 2

Rotation of paddle in airflow

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Figure 3

Comparison of aerodynamic forces on flat plate and paddle

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Figure 4

State control design for dc motor

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Figure 5

H2 state-feedback control with extended Luenberger observer

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Figure 6

Experimental setup for real-time airflow measurement

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Figure 7

Comparison between simulated results and actual measurement in rising-up step input of voltage

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Figure 8

Comparison between simulated results and actual measurement in falling-down step input of voltage

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Figure 9

Plots of (a) rotor speed and (b) torsional load against time under stationary air

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Figure 10

Plots of (a) rotor speed and (b) torsional load against time under airflow of 3 m/s

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Figure 11

Plot of torsional load due to airflow resistance in still air against squared relative speed

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Figure 12

Experiment results at airflow with speed of 1 m/s and directional angle of 60 deg

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Figure 13

Circuit diagram of stopped dc motor with additional resistance




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