KR20090103215A - Apparatus for metering water level with low band filter and functions of upper and lower limiting - Google Patents

Abstract

PURPOSE: An apparatus for metering water level with a low band filter and upper and lower limiting functions is provided to measure water level accurately by changing measurement error range according to the size of the saving facility. CONSTITUTION: An apparatus(100) for metering water level with a low band filter and upper and lower limiting functions comprises a measuring part, a zero adjustment part, a pulse computing part, and a communication part. The measuring part comprises a pulley, a weight compensation part, and an incremental pulse encoder or an absolute pulse encoder or an ultrasonic sensor. The pulley(101) measures the water level of the water stored in the saving facility. The weight compensation part(104) hangs on the both sides of the pulley and compensates a floater(102) and the weight of the floater. The incremental pulse encoder or the absolute pulse encoder or the ultrasonic sensor measures the rotation quantity of the pulley. The zero adjustment part set up center value of the pulse value calculated from the water level and the pulse computing part of the water measured in the measuring part. The pulse computing part sets up the upper value and the lower value of the pulse value of the water level measured in the measuring part as a band. The pulse computing part has a low-band filter filtering the low-pass pulse value. The communication part transmits the water level calculated from the pulse computing part.

Description

Water level measuring device with low pass filter and high and low limit function {APPARATUS FOR METERING WATER LEVEL WITH LOW BAND FILTER AND FUNCTIONS OF UPPER AND LOWER LIMITING}

The present invention relates to a low level filter and a water level measuring device having a high and low limit function. More specifically, the water level is measured by using a floating body floating in the water, and the water level generated by natural factors such as wind or spring. The present invention relates to a low-pass filter capable of correcting the amount of deformation and capable of precise level measurement, and a level measurement device having upper and lower limit functions.

In general, large-scale water storage facilities such as dams and reservoirs are equipped with a device for measuring the water level in order to efficiently manage the reservoir.

Even if the water level in a large-scale water storage facility changes by a small amount, for example, 1 cm, the total watershed of the storage facility is calculated as if millions of tons of water were introduced or discharged. Therefore, the accuracy of the measuring apparatus for accurately measuring the water level of such a facility is calculated | required.

As a conventional water level measuring device, a water level measuring device using a floating body floating in water is mainly used. The level measuring device includes a float floating on the surface of the water (float) and a pulley, and a weight that is wound on the pulley by a string and compensates for the weight of the float. And, the pulley is connected to a measuring device for converting the amount of rotation generated by the floating body to rise and rise by the change in the water level of the electric signal.

The conventional mechanical water level gauge configured as described above is provided with a micro level displacement correction device that maintains the value in units of 1 cm when the rotation amount is insignificant on the pulley shaft, that is, when the variation of the water level is within 1 cm.

Figure 1 is a simplified diagram showing a microdisplacement correction device of the water level measurement apparatus according to the prior art, the latch device 10 is used as the microdisplacement correction device, the configuration of the latch device 10 is the center of the pulley And a pulley shaft 12, a ratchet gear 11, a ball bearing 13, and a spring 14 provided on the shaft.

As the level of the latch device 10 changes, the pulley rotates, and the ratchet gear 11 rotates as the pulley shaft 12 connected to the pulley rotates. In order for the pulley to rotate, the teeth of the ratchet gear 11 can be moved only by pushing the ball bearing 13 and the spring 14.

At this time, the value of the difference between the diameter of the floor of the ratchet gear 11 and the diameter of the valley of the ratchet gear 11 multiplied by the spring constant k (F ₁ : Equation 1) is the change of buoyancy according to the change of the water level 1 cm. In the case of a larger value (F ₂ : Equation 2), there is a limit in which a change in the water level of 1 cm cannot be accurately measured.

On the other hand, in the conventional water level measuring device, the value of the measuring instrument changes as the floating body floats due to wind or a swell, and the physical change of the quantity becomes very large as the value of the measuring instrument changes.

In order to improve this, the conventional water level measuring device is designed to have a structure of a backlash mechanically, so that the intermediate value is measured when the water level is changed by wind or a shoulder.

However, the conventional water level measuring device is not practical because the structure of the mechanical backlash is complicated and difficult to adjust. In addition, the conventional water level measuring device is a friction between the mechanical backlash structure, and thus can not reflect the change of the water level quickly and accurately, there is a limit that can not consider the error according to the size, size of the water storage facility.

An object of the present invention is to solve the problems of the prior art described above, it is possible to accurately measure the water level of the water stored in the water storage facilities, such as dams or reservoirs, and to correct the amount of change in the water level by the wind or spring, measurement error It is to provide a water level measuring device having a low pass filter and an upper, lower limit function so as to reduce the.

The low-pass filter and the water level measuring device having a high and low limit function according to the present invention for achieving the above object is installed in a storage facility for storing a large amount of water, as a water level measuring device for measuring the water level of the storage facility, To measure the water level of the water stored in the storage facility, a pulley, a weight compensating unit that is suspended on both sides of the pulley by a rope and compensates the weight of the floating body and the floating body, and measures the amount of rotation of the pulley A measuring unit having an incremental pulse encoder or an absolute pulse encoder or an ultrasonic sensor, a zero point adjusting unit for setting an initial value of a water level measured by the measuring unit and a pulse value calculated by the pulse calculating unit as an initial value, and in the measuring unit By setting the upper and lower limits of the measured pulse level pulse value as a band, the center value of the pulse value measured in the band is calculated. And a communication unit for the pulse calculating section has a low-pass filter for filtering low-band pulse values to the pulse wave value according to the water level of the water measured by the measuring unit transmits the water level calculated by the calculating section to the pulse group.

The low pass filter and the water level measuring device having the upper and lower limit functions according to the present invention configured as described above can accurately measure the water level stored in the water storage facilities such as dams or reservoirs, It can be calibrated to reduce the measurement error. In addition, the present invention can easily change the measurement error range according to the size of the storage facility it is possible to make a more precise measurement.

1 is a simplified view showing a latch device of the water level measuring apparatus according to the prior art.

2 and 3 are a front view and a side view of the water level measuring device according to the present invention.

Figure 4 is a block diagram showing a pulse calculation unit of the water level measuring device according to the present invention.

5 is a data processing flowchart of a water level meter using a pulse encoder of the water level measuring device according to the present invention.

6 is a flowchart illustrating a zero point setting process of the water level measuring device according to the present invention.

7 is a flow chart showing a level value calculation process of the water level measuring device according to the present invention.

8 is a graph showing measurement data obtained by the water level measuring device according to the present invention in comparison with a conventional water level measuring device.

9 is a reference diagram for explaining the weaving of the direction plate of the water level measuring apparatus according to the present invention.

10 is a view showing the characteristics of the water level change by the FIR filter.

11 is a block diagram showing a pulse calculation unit of the water level measuring device according to another embodiment of the present invention.

12 is a data processing flowchart of the water level gauge using the ultrasonic sensor of the water level measuring device according to another embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 and 3 are a front view and a side view of the water level measuring device according to the present invention.

The water level measuring device 100 having a low pass filter and a high and low limit function according to the present invention is installed in a storage facility for storing a large amount of water, and measures the water level of the water stored in the storage facility.

To this end, the water level measuring apparatus 100, as shown in Figure 2 and 3, is provided with a cradle 105 for fixing to the work place. In addition, the cradle 105 is provided with a measuring unit for measuring the level of water stored in the storage facility.

The measuring unit includes a pulley 101 rotatably installed in the holder 105, the pulley 101 is connected to the pulley 101 by a string 103 is suspended to both sides of the pulley 101 and Weight compensation unit 104 is installed. The floating body 102 is made to float to a certain height on the surface of the water, the weight compensation unit 104 compensates the weight of the floating body 102, the floating body 102 smoothly in accordance with the change in the water level Allow it to move. In addition, an encoder 116 interlocked with the pulley 101 and measuring a change amount of the water level is installed.

To this end, the shaft 111 is installed on the rotating shaft of the pulley 101, the shaft 111 is supported by a bearing 113 installed on the support body 112. In addition, upper and lower timing pulleys 115a and 115b are installed at the shaft 111 and the encoder 116, and the upper and lower timing pulleys 115a and 115b are connected by a timing belt 114.

In the embodiment of the present invention, the measuring unit is made to measure the water level according to the displacement of the floating body 102, including the floating body 102, the pulley 101, the weight compensation unit 104, the encoder 116. Can be.

On the other hand, the measurement unit may also be made of an ultrasonic sensor that can measure the distance directly.

The measurement unit is provided with a pulse operation unit 200 for calculating the pulse value of the water level measured by the encoder 116 as an effective pulse value in accordance with the displacement of the floating body (102).

The pulse operation unit 200 is configured to reduce the error according to the amount of change of the water level according to the natural environment, such as wind or swell, by setting the upper and lower limits of the pulse value of the measured water level as a band, which is measured in the band The center value of the pulse value is calculated.

Figure 4 is a block diagram showing a pulse calculation unit of the water level measuring device according to the present invention, Figure 5 is a flow chart of the water level meter using a pulse encoder of the water level measuring device according to the present invention.

4 and 5, the pulse operation unit 200 will be described in detail as follows.

The pulse calculating unit 200 of the water level measuring apparatus 100 according to the present invention includes a central processing unit (CPU) 204, a display device 201, a keyboard 202, a pulse encoder for inputting a parameter or checking a status. A pulse integrating unit 203 for integrating and storing the signal of 214, a memory 205 composed of a flash ROM, a static RAM, and the like, and having a function of sending water level data to an external device. / Wireless communication unit 206, zero switch 207 and digital input unit 208 for setting the initial value of the water level, analog output unit 209, pulse encoder 214 for outputting the water level value as an analog value Pulse input unit 210 for shaping a waveform and separating direction signal and pulse input, and a backup battery 211 for supplying power to arithmetic unit to maintain a center value or a current value in case of a momentary or long-term power failure. ), The water level value to the external device is BCD (Bina It is composed of a BCD output unit 212, 4 ~ 20mA output unit 213, a pulse encoder 214, a power supply unit 215 for supplying power.

The wired / wireless communication unit 206 outputs a water level value, either a BCD output or a wired communication method communicating with a predetermined protocol by RS-232C or RS-485 in addition to 4 to 20 mA, 424 MHz or Select one of the wireless communication methods such as ZIGBEE, Bluetooth, and CDMA modem. Here, Zigbee communication (ZIGBEE), Bluetooth (Bluetooth) is a high transmission speed, but due to the environmental impact a lot of communication obstacles are not secured by the leaves or buildings, but in the case of 424MHz Low data enables smooth data transmission outdoors.

In addition, if the use of CDMA, a predetermined fee is added, but many base stations are installed throughout the country, and thus, there is an advantage in that data can be easily transmitted anywhere in the country when a cell phone is transmitted and received.

As the pulse encoder 214, an incremental pulse encoder and an absolute pulse encoder are mainly used. The incremental pulse encoder outputs two signals having a 90 degree phase difference from the A signal, and determines the phases of the A and B signals to determine a pulse increase or decrease signal.

Meanwhile, the pulse integrator 203 integrates and stores the signal of the pulse encoder 214, and when the incremental pulse encoder is used, analyzes the phases of the A and B signals and divides them into forward or reverse signals. do. In addition, the pulse integrating unit 203 has a circuit for outputting a forward pulse when the shaft 111 of the pulley 101 rotates clockwise, and a reverse pulse when the shaft 111 of the pulley 101 rotates clockwise, and integrating these signals. The change in water level is stored continuously.

In addition, when the absolute pulse encoder is used, the pulse integrator 203 outputs 10 bits (1 rotation / 1024) or 12 bits (1 rotation / 4096) or the like per rotation. The pulse integration unit 203 can always read the rotation value of the axis.

In general, the circumferential length of the pulley 101 is 1 m, and one rotation of the pulley 101 is such that the water level is 1 m. Therefore, if the number of teeth of the upper and lower timing pulleys 115a and 115b of the measuring unit is the same and the encoder 116 is used to output 1000 pulses per revolution, the resolution of the pulse operation unit 200 is increased by four times. One round of 116 will give you a signal of 4000 pulses.

At this time, if the minimum precision (dx) per pulse obtained by the encoder 116 is calculated, Equation (3).

As such, the minimum precision (dx) per pulse obtained by the encoder 116 is 0.025 mm, and 400 times more accurate level measurement is possible than 1 cm, which is the resolution of the existing level measurement apparatus.

In general, the water level of the water stored in the storage facility is represented by the altitude above sea level, and the initial position of the water level measuring apparatus 100 is set to a position relative to the altitude above sea level.

Referring to FIG. 6, which is a flowchart illustrating a zero setting process of the water level measuring apparatus 100 according to the present invention, the zero setting sequence is ON when the initial value is set to a parameter (S11) and the zero input signal is 'ON'. Integrating the time (S12, S13), checking whether the ON time integration value is greater than or equal to the set value (S14), and if the ON time integration value is greater than or equal to the setting value, inputting an initial value to the center value. Step S15 consists of inputting an initial value to the present value (S16).

At this time, the step of checking whether the integrated value of ON time is equal to or larger than the set value is when the zero signal is temporarily inputted by external disturbance (noise) and disappears. To prevent this problem, the center value and the present value must be initialized only when the ON signal is kept above the set value.

In addition, the operation of the pulse operation unit 200 will be described in more detail as follows. In measuring the water level in mm units, the water level measuring apparatus 100 may generate waves of the surface due to wind influences or global environmental effects such as moons and planets, and thus the water level data may be frequently changed within several mm. Likewise, if the data value changes frequently, calculation errors are likely to occur, and the reliability of the data may be deteriorated due to frequent data changes. Therefore, the pulse operation unit 200 sets the upper and lower limit values of the measured pulse level pulse values as a band, and calculates the center value of the pulse values measured in the band.

To this end, the pulse operation unit 200 implements a function similar to the conventional mechanical backlash function in software. As described above, the pulse operation unit 200 may reduce the error caused by friction due to mechanical driving as the micro-error is implemented by software, and it is easy to set the micro-error according to the size of the storage facility. It is convenient.

7 is a flow chart showing a level value calculation process of the water level measurement apparatus 100 according to the present invention. Referring to FIG. 7, the step of calculating the water level value by the action of the pulse calculating unit 200 includes increasing the calculation time by one each time (S21), checking whether the calculation time is equal to or greater than a setting period (S22), If the total value of the calculation time is equal to or greater than the setting period, the operation time is set to '0' (S23), the center value and the upper limit band are added to the upper limit value (S24), and the lower limit band is subtracted from the center value. Step S25, checking whether the present value is greater than the upper limit value (S26), if the present value is greater than the upper limit value, subtracting the upper band from the present value and substituting it into the center value (S27), and the present value is lower than the lower limit value. It is a step of checking whether it is small (S28), and if the present value is smaller than the lower limit, adding the present value and the lower limit band and substituting it into the center value (S29).

On the other hand, in the water level measuring device 100 according to the present invention, the stop torque of the encoder 116 is about 10 g-cm or less, which is much smaller than the value of the radius of the pulley 101 multiplied by the change in buoyancy according to the water level change. And, there is little effect on the vertical movement of the floating body 102 according to the change in water level.

Table 1 is a table comparing the measurement data obtained by the conventional water level measuring apparatus 100 and the water level measuring apparatus 100 according to the present invention at the same place. 8 is a graph showing the measurement data obtained by the water level measuring apparatus 100 according to the present invention in comparison with the conventional water level measuring apparatus 100. Looking at the data measured by the conventional water level measuring device 100 can be confirmed that the water level measuring device 100 of the present invention is precisely measured in units of 1mm, while being displayed in a stepwise manner in units of 1 cm.

On the other hand, if you look at Table 1 in detail, you can be affected by wind fluctuations of the surface of the water or the long cycle of the moon and the global environment.

Referring to FIG. 9, which is a reference diagram for explaining the direction of the direction plate of the water level measuring apparatus 100 according to the present invention, the data flow of the pulse calculating unit 200 inputs a pulse according to the change of the water level in the pulse encoder 214. As shown in Fig. 9, the phase difference between the A and B phases is compared in each direction plate, and when the A phase rises, the B phase is '0' and the B phase is '1' when the A phase rises. If it is sent to (203), the pulses are integrated.

The pulse number is multiplied by a mechanical constant parameter for setting a water level value per pulse to the pulse integrated part 203, and the number of pulses is converted into mm units, and a noise signal is generated using a low band filter. Remove In this case, the low pass filter is a low pass filter for filtering the change value of the low frequency (Low Pass Filter).

The digital filtering method using the low pass filter is divided into Infinite Impulse Response methode (IIR) and Finite Impulse Response methode (FIR), where h (k) of the FIR filter has finite values but h (k) of the IIR filter. Has infinite values. Indeed, it is impossible to calculate infinite in order to calculate. In the case of IIR filter, a certain amount of past output value is fed back to the present value to calculate the present y (n).

Here, the FIR filter is always stable and has a linear phase response property, but the IIR filter cannot always be guaranteed to be stable and the phase response is nonlinear.

The higher the order of the FIR filter, the better the data filtering but the delay of the signal.

In the water level measuring apparatus 100 of the present invention, it is possible to set the order of the filter in the parameter so that it can be selected according to the site conditions.

Equation y (n) of the FIR filter is expressed as shown in [Equation 4].

At this time, the characteristic of the water level change by a FIR filter is shown in FIG.

As such, the water level measuring apparatus 100 of the present invention removes noise components caused by wind or spring and adjusts the water level more accurately by adjusting the coefficient value appropriately using a low band filter using a stable FIR filter. Can be derived.

In addition, the low-pass filter of the FIR method removes the noisy signal by the filter order parameter and performs a level value calculation process on the upper and lower bands by the upper and lower band parameters to output the center value.

Therefore, if the data measured by the pulse operation unit 200 of the water level measuring device 100 is sequentially stored in the memory 205 and averaged or filtered using a numerical analysis method in software, this noise component is removed more accurately. The level value can be calculated.

11 is a block diagram illustrating a pulse calculating unit 200 of the water level measuring apparatus 100 according to another embodiment of the present invention, and FIG. 12 is an ultrasonic sensor of the water level measuring apparatus 100 according to another embodiment of the present invention. Flow chart of water level using

Referring to FIG. 11, the pulse operation unit 300 of the water level measuring device 100 according to another embodiment of the present invention is a central processing unit (CPU) 304 and a display device 301 for inputting parameters or checking status. ) Memory 305 consisting of keyboard 302, Flash ROM, Static RAM, etc., Wire / Wireless communication unit 306 for sending water level data to external devices, Initial level of water level meter A zero point switch 307 and a digital input unit 308 for setting a value, an analog output unit 309 for outputting a water level value as an analog value, and a sensor for receiving a reflected wave by an ultrasonic signal generated from the ultrasonic sensor 314 Matching unit 310, a backup battery 311 for supplying power to the operation unit to maintain the center value or the current value in the case of a momentary or long-term power failure, BCD (Binary Coded Decimal) BCD output unit 312 for outputting in the form, 4 ~ 20mA an output unit 313 and the ultrasonic sensor 314, a power supply 315 for supplying power.

Referring to FIG. 12, when the measurement unit is a water level measuring device 100 including an ultrasonic sensor 314, a predetermined pulse is generated by a trigger signal of a trigger signal generator to excite the ultrasonic sensor 314. At 314, the ultrasound is output. The ultrasonic waves emitted by the ultrasonic sensor 314 are reflected by an object to generate reflected waves. When the reflected signal is amplified by the signal amplifier and the timer is initialized by the trigger signal by the reflection time detector, the clock is accumulated by the reference time generator, and when the reflected signal is input, the time-displacement calculator inputs the time value from the trigger signal generation. The distance is converted to the input time value by multiplying the propagation time constant of the sound wave according to the temperature.

In this case, as shown in FIG. 12, which is a data processing flow chart of the water level measuring device 100 using the ultrasonic sensor 314, the upper and lower limit band calculators output the center value by limiting the calculated value. Due to the characteristic of 314), the center value is severely shaken to remove the phenomenon, thereby enabling stable water level measurement.

As a result, a low-pass filter that adjusts the order of the measured data by the parameter in the water level measurement is implemented to remove the noise component and implement the upper and lower bands that can be set again as parameters. In this band, the current value is frequently The center value can be output even if it changes.

Although the water level measuring apparatus 100 according to the present invention as described above with reference to the illustrated drawings, the present invention is not limited by the embodiments and drawings described above, the present invention within the scope of the claims Of course, various modifications and variations can be made by those skilled in the art.

Claims (1)

It is installed in a storage facility that stores a large amount of water, and is a water level measuring device for measuring the water level of the storage facility, To measure the water level of the water stored in the storage facility, a pulley, a weight compensating unit that is suspended on both sides of the pulley by a rope and compensates the weight of the floating body and the floating body, and measures the amount of rotation of the pulley A measuring unit having an incremental pulse encoder or an absolute pulse encoder or an ultrasonic sensor, A zero point adjusting unit for setting the water level measured by the measuring unit and the center value of the pulse value calculated by the pulse calculating unit as an initial value; In order to calculate the center value of the pulse value measured in the band by setting the upper limit value and the lower limit value of the pulse value of the water level measured by the measurement unit as a band, the low-pass pulse to the pulse value caused by the wave in the water level measured by the measurement unit. A pulse calculation unit having a low pass filter for filtering a value, And a low pass filter and a high and low limit function, characterized in that it comprises a communication unit for transmitting the water level calculated by the pulse calculation unit.