·Table of Contents
·Methods and Instrumentation
The Research for the Measurement of the Moving and Vibration of the Dam SystemZhao Jiyin Zhao Jingrong Huang Ting Gai Shuang
School of Information Science & Engineering, Jilin University of Technology,
Changchun, China 130025
|Fig 1: The principle of the measurement|
No.1, No.2, and No.3 are three poles, and they are connected through float mechanism. No.2 pole does not move as the dam moving or vibrating. No.1 and No.3 poles produces proportional moving as the dam moving or vibrating, but the distance between No.1 and No.3 poles does not change. The three measuring poles will be projected on CCD image sensor (it is shown in figure 1(a)). The output signal in figure 1(c) is produced by CCD under the action of CCD frame alignment signal which is shown in figure 1(b). The moving signal is produced after the signal is processed (it is shown in figure 1(d)). So we can get four positions of three levers as follows:
Where L2 and L3 are horizontal moving of the dam along the direction of current. L1 and L4 measure ranges of the measuring system. The vibration of the dam can be calculated according to formulas (2) and (3). It is showing in following formula
|DL=(L2-L3)/2=(N2-N3) / 2 + (D1-D3) /4||(5)|
In a word, After the formulas (1), (2), (3), (4) and (5) are carried out data processing and calculated by MCS-51 signal chip, the moving and vibration can be measured on-line and be monitored continuously.
|(1) Effective image element:||5000|
|(2) The area of image element:||7mm´7mm|
|(3) Drive mode:||2 phases|
|(4) Whole length of photosensitive unit array:||35mm|
|(5) Feature of spectrum response is shown in figure 2|
|Fig 2: Spectrum response feature of TCD106C|
Considering measure range in system of displacement measurement, we adopt two pieces TCD106C for displacement measurement along the dam of orientation of current. And we adopt one piece TCD106C for displacement measurement across the dam of orientation of current.
|Fig 3: light track of parallel light system|
In the above figure: 1: reflector, 2: lamp-house, 3: diaphragm, 4: grating 5: field lens .
The light, which is eradiated by lamp-house of halide tungsten , is made through focus-glass, diaphragm, and field lens to pool parallel beam in order to make shadow of needle imaged in CCD surface. The system of parallel light both possesses higher degree of parallel and improves the rate of use. Under the conditions of satisfying CCD light intension at fact power, lamp-house of halide tungsten can be used at low-power and advance the life-span of use. For decreasing optical discrepancy, field lens adopt double-glued lens. Movable protect-shell in this system both keeps the system of parallel light and imaging system, and decreases pollution of dust for the system of measuring pathway. The bulk of photo-machinery structure is very small. It is resolved that the key problem to the dam displacement measurement .
|Fig 4: The main structure of the system|
The three measuring poles will be projected on CCD image sensor because of the irradiation by the parallel light. Then we can get the video signal from CCD driven by phase impulse f1 and f2, reset impulse RS and frame synchronization impulse SH.
And we can get the digital signal of the displacement from the video signal by amplification, demodulation, compare circuit and signal-locked process. Under the control of the SCM the video signal goes through WR generation circuit, address generation circuit and data generation circuit, and then the digital signal would be saved in double-ports RAM IDT7032 by itself. SCM 8031 processes data and displays the result after the measurement period controlled by SH. At the same time SCM transmit the measurement data and status to the industrial controlling computer by RS-485 communication agreement. Then we can realize the on-line monitoring and recording. We mixing the digital signal of dam displacement and 32MHz standard clock signal to increase the distinguish-rate and measurement precision of the system.
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