CN105160075B - A kind of application of farmland irrigated area open channel measuring automatically flow mathematical model - Google Patents

Abstract

An application of an automatic flow measurement mathematical model of an open channel in a farmland irrigation area, the application is based on the automatic flow measurement model of an open channel in a farmland irrigation area, and realizes the application of automatic flow measurement in an open channel in a farmland irrigation area; the mathematical model is composed of a flow measurement device and a control system The application is to fix the model of the open channel flow measuring device in the irrigation area above the channel to be measured, put the pendulum in the open channel, and the water flow impacts the pendulum to make it deflect at a certain angle, and collects the deflection angle of the pendulum through the pulse signal of the photoelectric encoder. Comparing the deflection angle of the pendulum with the previously established mathematical model, the flow rate of the open channel in the farmland irrigation area can be obtained. The invention establishes a mathematical model, utilizes water flow to impact the pendulum to make it deflect at a certain angle to detect the flow of open channels in farmland irrigation areas, and processes through single-chip microcomputer technology to realize automatic flow measurement in open channels in farmland irrigation areas, which improves the accuracy of flow measurement, and is cheap and convenient for irrigation areas. Promote apps.

Description

Application of a Mathematical Model for Automatic Flow Measurement in Open Channels in Farmland Irrigation Areas

technical field

The invention relates to an automatic flow measurement device and method for open channels in irrigation areas. Specifically, a pendulum rod of an automatic flow measurement mathematical model is placed in the open channel, and the water flow hits the pendulum to make it deflect at a certain angle, and passes through a photoelectric encoder. The pulse signal collects the deflection angle of the pendulum, and compares this angle with the previously established mathematical model to obtain the flow rate of the open channel in the farmland irrigation area.

Background technique

Flow detection plays an important role in the field of farmland water conservancy and hydrological testing, and it is an important part of testing technology. To realize the real-time detection of open channel flow, the key lies in whether the flow detection system can detect the flow value in time and accurately. With the continuous development of science and technology, there are more and more detection devices and methods for open channel flow. The open channel flow measurement methods that have been used in my country are mainly the flow velocity area method, the weir channel method, and the water level flow relationship method. There are also experimental solution method flow measurement methods, and acoustic flow measurement methods have gradually become a new flow measurement method.

In open channel measurement, the traditional triangular weir flow measurement is the main method, which mainly uses the relationship between the water head on the weir and the flow rate to calculate the flow rate of the channel. Calculation expression of triangular weir flow measurement: Q=Ch ^5/2 , where C means that the relevant channel coefficient can be obtained by looking up the table, h is the water head on the weir, the flow measurement operation is simple, and the unknown parameter is only h, so it is easy to find the channel flow. However, when the water level is relatively high, the water surface fluctuates greatly, and the height measurement accuracy of the water level cannot reach the corresponding height, so there is an error in the flow calculation.

With the introduction of sound waves, new technologies have been injected into open channel flow measurement. The ultrasonic probe is mainly used to measure the flow velocity at corresponding points on the measurement line. Using the relevant knowledge of hydraulics, one-point method, three-point method, five-point method, etc. can be used to calculate Obtain the flow velocity of the measuring line on the cross-section, and obtain the average flow velocity of the cross-section through the flow velocity of the measuring line after dividing the cross-section, and use the formula Q=AV, which is the velocity area method, to calculate the cross-sectional flow. This measurement method is relatively complicated, but it can accurately reflect the flow of water, and the flow measurement value is relatively accurate.

At present, there are also a series of electromagnetic flowmeters used, mainly based on the "flow velocity-water level" algorithm, through the real-time calculation of the microprocessor, to accurately measure the velocity of the water flow, and then calculate the flow value, but because the electromagnetic flowmeter is used in open channel measurement Has a wider range of applications. However, due to its high price, complicated installation and debugging compared with other flowmeters and stricter requirements, it cannot be used more widely.

The above-mentioned existing devices and methods capable of detecting channel flow are still constrained by the measurement environment and the user's economic conditions, which limits the scope of application. Based on this, a simple structure, flow measurement It is very necessary to have an automatic flow measurement device and method for farmland irrigation open channels that are fast, convenient, low in cost, wide in application range and not affected by the flow measurement environment.

Contents of the invention

According to the method and principle of open channel flow measurement, in order to accurately calculate the cross-section flow, it is necessary to measure the flow velocity of the cross-section measurement point and the relevant parameters of the water level. As long as there are obstacles in the water, the flow state of the water will change greatly, resulting in the flow velocity of the measurement point. The inaccuracy will affect the flow measurement results. When the water level is high, the water surface fluctuations are relatively large, and the water level measurement accuracy cannot meet the requirements, which will also greatly affect the flow calculation results. Measurement errors are generated, which affect the measured flow.

In order to overcome the deficiencies of the above-mentioned prior art, the object of the present invention is to provide an application of a mathematical model for automatic flow measurement of open channels in farmland irrigation areas.

The above object is achieved through the following technical solutions.

An application of an automatic flow measurement mathematical model of an open channel in a farmland irrigation area, the application is based on the automatic flow measurement model of an open channel in a farmland irrigation area, and realizes the application of automatic flow measurement in an open channel in a farmland irrigation area;

The mathematical model of the automatic flow measurement of the open channel in the farmland irrigation area is to design a model of the open channel flow measurement device in the irrigation area and fix it above the channel to be measured, and control the water level of the channel by controlling the change of the water level in the storage tank. After the water level is stable, a uniform flow with different flow rates is formed. The flow corresponds to the different deflection angles of the device, and the angle is transmitted to the single-chip microcomputer through the photoelectric encoder, and the flow is measured by the triangular weir or the flow meter, and a series of obtained values are fitted into a function curve of angle and flow, which is determined by repeated experiments This function curve establishes a mathematical model of angular flow, writes the mathematical models of different channels into the single-chip program, and compares it with the measured angle value of the actual channel to be tested, thereby outputting the flow value of the channel to be tested;

The application of realizing the automatic flow measurement of the open channel in the farmland irrigation area is to fix the model of the open channel flow measurement device in the irrigation area above the channel to be measured, put the pendulum into the open channel, and the water flow hits the pendulum to make it deflect at a certain angle, and the photoelectric encoder pulses The deflection angle of the pendulum rod is collected by the signal, and the deflection angle of the pendulum rod is compared with the previously established mathematical model to obtain the flow rate of the open channel in the farmland irrigation area;

The model of the open channel flow measurement device in the irrigation area is composed of a flow measurement device and a control system; the measurement device is a gate-shaped structure formed by a symmetrical channel deck fixed with a lifting bracket supported by a detection platform, and erected in the farmland irrigation area. On the open channel channel; one end of the detection platform is installed with an infrared range finder Ⅰ, and the other end is equipped with a control instrument box, and the stepping motor Ⅰ and stepping motor Ⅱ are installed at both ends of the detection platform, and are connected and rotated by a screw; The pendulum and its photoelectric encoder, infrared rangefinder II and level are installed on the screw rod through the encoder mounting bracket; the control system is equipped with a single-chip microcomputer, signal acquisition and transmission circuit, power supply, test and mode in the instrument control box. The selection button and the liquid crystal display are connected by wires to control the infrared range finder Ⅰ, the infrared range finder Ⅱ, the photoelectric encoder and the lifting bracket.

Wherein, the open channel of the open channel automatic flow measurement mathematical model in the farmland irrigation area is one of U-shaped, trapezoidal and rectangular.

Compared with the prior art, the application of the above-mentioned automatic flow measurement mathematical model for open channels in farmland irrigation districts has the following advantages and positive effects.

The present invention overcomes the constraints of the existing open channel automatic flow measurement device and method in farmland irrigation areas, which are restricted by the measurement environment and economic conditions, and makes the structure of the flow measurement device simple, the flow measurement method fast and convenient, low in cost, wide in application range and not affected The influence of water flow measurement environment has more practical application value.

The invention establishes a mathematical model and uses water flow to impact the pendulum to make it deflect at a certain angle to detect the open channel flow in the farmland irrigation area, and the automatic flow measurement is mainly realized through single-chip microcomputer technology processing. As a new technology in the era of microelectronics, single-chip microcomputer technology is used in the automatic flow measurement of open channels in farmland irrigation areas because of its unique advantages such as small size, low price, strong function, fast running speed, high reliability, and convenient and flexible use. , improve the accuracy of flow measurement, realize online real-time continuous detection, and the price is low, which is convenient for popularization and application in irrigation areas.

The invention organically combines flow measuring technology, sensing technology and automatic control technology. The angle deflection is used to detect the flow of farmland open channels in real time, which reduces the input of manpower and material resources, has little impact on the external environment and is easy to install and maintain. It has laid a certain foundation for the development of the modern open channel flow detection industry.

Description of drawings

Figure 1 is a schematic diagram of the application structure of the automatic flow measurement mathematical model of the open channel in the farmland irrigation area.

Fig. 2 is a block diagram of the control circuit for the application of the mathematical model of automatic flow measurement in the open channel of the farmland irrigation area.

In the figure: 1: Channel deck; 2: Lifting bracket; 3: Inspection platform; 4: Stepper motor Ⅰ; 5: Infrared range finder Ⅰ; 6: Screw rod; 7: Control instrument box; 8: LCD display ;9: Channel mode selection button; 10: Measuring switch; 11: Meter box holder; 12: Stepper motor II; 13: Fixing screw; 14: Encoder mounting bracket; 15: Photoelectric encoder; 16: Coupling ; 17: pendulum; 18: spirit level; 19: infrared range finder Ⅱ.

Detailed ways

The specific embodiment of the present invention is described in further detail below in conjunction with the accompanying drawings, so that technical personnel in this field can make the automatic flow measurement mathematical model of the open channel of the farmland according to the specific embodiment, and can apply the automatic measurement of the open channel of the farmland The flow mathematical model measures the flow of the channel to be tested, digitally displays and monitors remotely.

A mathematical model for automatic flow measurement of open channels in the farmland irrigation area is specifically implemented. In the U-shaped, trapezoidal or rectangular channels of standard specifications established in the laboratory, a mathematical model of the open channel flow measurement device in the irrigation area must be fixed above the channel, and the water level in the channel can be controlled by controlling the change of the water level in the storage tank. Different After the water level is stabilized, a uniform flow of different flow rates is formed. Different flow rates correspond to different angle deflections of the device. The angle is transmitted to the single-chip microcomputer through the photoelectric encoder. The flow rate is measured by a triangular weir or a flow meter, and the obtained series of values are fitted into a function curve about the angle and flow rate. Through repeated experiments to confirm the reliability of this function curve, the mathematical model of angular flow can be established. A large number of experimental data and actual channel measurements have verified the reliability of the mathematical model. This novel mathematical model has also established a new method of flow measurement, and the mathematical model is the inventor's previous work in the laboratory. Producers and consumers bring any trouble. The mathematical model is compiled into the control system program, and the user only needs to operate it simply.

The specific implementation of an automatic flow measurement model of an open channel in an irrigation area is to fix the model of a flow measurement device in an irrigation area above the channel to be measured, and put the pendulum of the flow measurement device into the open channel, and the water flow will hit the pendulum to make it deflect by a certain amount. Angle, through the pulse signal of the photoelectric encoder to collect the deflection angle of the pendulum rod, compare this angle with the mathematical model established before, and obtain the flow of the open channel channel in the farmland irrigation area.

Specifically implement a device model for automatic flow measurement of open channels in farmland irrigation areas, including a measurement system, a control system, a vertical lifting support, a horizontal displacement platform and a wireless communication module;

The measurement system includes a photoelectric encoder mounting bracket 14 , a photoelectric encoder 15 , a shaft coupling 16 and a swing rod 17 . Described measurement system is connected with the horizontal displacement platform that controls measurement system to move left and right by encoder mounting bracket 14, and described photoelectric encoder 15 is Omron 500 line encoders; Described coupling 16 and photoelectric encoder 15 are supporting products; The swing rod 17 is a solid aluminum alloy rod with a diameter of 5 mm, a weight of 200 grams, and a length of 60 cm. When the specific angle is detected, the channel water flow impacts the swing rod, causing the swing rod to deflect at a certain angle. The photoelectric encoder 15 The angle value is recorded through the change of the pulse, and passed into the program of the one-chip computer.

This control system, that is, the integrated circuit of the system is mainly concentrated in the instrument control box 7, including the minimum system of the single-chip microcomputer, signal acquisition and transmission circuit, power supply, test and mode selection buttons, and liquid crystal display. The core of the control system is the minimum system of the single-chip microcomputer , the angular flow models of different channels established in the experiment are written into the single chip microcomputer, and the single chip microcomputer is also responsible for collecting and processing various signals, including collecting channel width and height signals, channel mode, control signals of two stepper motors, etc., and passing angle deflection The numeric value gets the traffic value of the channel. The power supply module includes a 12V independent power supply, and provides a 5V power supply through a voltage stabilizing module.

The vertical lifting support includes channel deck 1, lifting support 2, stepper motor I4 and fixing screw 13. The fixed deck 1 is made of aluminum alloy, and the whole device can be fixed on the channel to be tested with screws and nuts. The lower end of the lifting bracket 2 is welded on the channel deck 1, and the lifting bracket is controlled by a stepping motor I4 2 vertical moves.

The horizontal displacement platform includes a detection platform 3, an infrared range finder 5, a screw rod 6; a stepping motor 12 and a level 18. The horizontal displacement platform is fixed on the detection platform 3, and the rotation of the screw rod 6 is controlled by the stepping motor II12 so that the measurement system is located in the middle of the channel to measure the flow. The infrared range finder I5 is used to measure the distance in the horizontal direction and sent to the single chip microcomputer to control the movement of the motor, and the level meter 18 is used to detect whether the horizontal displacement platform is level.

This wireless communication module transmits data with a computer or mobile phone through a Bluetooth serial port, enabling staff to monitor the flow value in real time.

The specific implementation manners of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Fig. 1, implement a kind of application of the automatic measurement flow measurement model of the open channel of farmland irrigation area, comprise angle measuring mechanism, described angle measuring mechanism consists of encoder mounting bracket 14, high-precision photoelectric encoder 15, shaft coupling 16 and pendulum Bar 17 several parts constitute. The encoder mounting bracket 14 is connected with the screw rod that controls the left and right movement of the angle measuring mechanism. The swing rod 17 is a solid aluminum alloy rod with a diameter of 5 mm, a weight of 200 grams, and a length of 60 cm. The rod 17 makes the pendulum 17 deflect at a certain angle, and the photoelectric encoder 15 records the angle value through the change of the pulse, and transmits it into the program of the single-chip microcomputer. Fig. 1 also includes a control meter box 7 and a meter box bracket 3, and the meter box is provided with a liquid crystal display 8, a channel selection button 9, a power switch and a test switch 10. The instrument box bracket 3 is used to fix the instrument box 7. The instrument box 7 includes a control module, namely a single-chip microcomputer, a signal acquisition and signal transmission circuit, a wireless transmission Bluetooth module and a power supply, and infrared range finders 5, 19 and a level 18 are also fixed on the bracket. , Two stepper motors I4 and stepper motor II12, and screw mandrel 6. The mathematical model established in the previous experiment was written into the single-chip microcomputer. The infrared range finder Ⅰ5 detected the width of the channel and sent the value to the single-chip microcomputer. After the single-chip program was processed, the stepper motor was driven to rotate the screw to make the pendulum in the center of the channel for angle measurement. Finally, the angle is converted into the flow value of the channel through the mathematical model established in the early stage and displayed on the LCD 8. The wireless transmission Bluetooth module can realize wireless transmission of data within a certain distance. The level meter 18 is used to adjust the device to make it level, and the infrared distance measurement Instrument Ⅱ19 is used to detect the distance between the device and the bottom of the channel, and the 12V battery supplies power to the entire control module, and provides 5V power through the voltage stabilizing module. The liquid crystal display 8 in the upper left corner of the panel of the instrument box 7 is used to display the flow value of the open channel, and the channel selection button 9 has 3 buttons, which can respectively select several common open channels such as rectangular channels, U-shaped channels, and trapezoidal channels. When using, select the channel mode according to the specific channel, and different modes correspond to different mathematical models. FIG. 1 also includes a fixing device channel card slot 1 , a lifting bracket 2 and fixing screws 13 . The channel card slot 1 uses fixing screws 13 to fix the lifting bracket 2 on the channel to be tested, and the lifting bracket 2 is controlled by the stepping motor I4 to lift it up and down.

In specific use, the operation is convenient and simple, just use the fixing screws 13 to fix the channel card slot 1 on both sides of the channel to be tested, and refer to the level meter 18 to level the whole device, turn on the power, select the channel mode, press the test button, and the program drives The stepper motor drives the screw mandrel and the lifting table so that the pendulum 17 is in the best position for testing, and the flow of the channel to be tested is displayed on the liquid crystal display 8 .

At present, there are various flow detection systems in various fields at home and abroad. However, many detection devices are often restricted by many conditions, such as high prices, limitations of the use environment, and difficulties in installation, which limit their use range. The automatic flow measuring device of the invention has the advantages of simple structure, low price and convenient operation. The farmland open channel automatic flow measurement device can solve the disadvantages of the traditional water measurement method to a certain extent, and can realize automatic flow measurement and real-time monitoring. At the same time, the price is much lower than other water measuring methods, and has broad application prospects.

The basic principles, main features and advantages of the present invention have been described above. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments. What are described in the above-mentioned embodiments and description are only the principles of the present invention. Under the premise of not departing from the spirit and scope of the present invention, the present invention also has various changes and improvements, and these changes and improvements all will fall within the claimed scope of the present invention, and the protection scope of the claimed invention is defined by the appended claims Requirements and their equivalents are defined.

Claims (2)

1. An application of the automatic flow measurement mathematical model of the open channel in the farmland irrigation area, characterized in that the application is based on the automatic flow measurement mathematical model of the open channel in the farmland irrigation area, and realizes the application of the automatic flow measurement of the open channel in the farmland irrigation area; the automatic flow measurement of the open channel in the farmland irrigation area The mathematical model is established through the following steps: (1) Design a model of the open channel flow measuring device in the irrigation area and fix it above the measured channel. The water level of the channel is controlled by controlling the change of the water level in the storage tank. After the water level is stable, a uniform flow with different flow rates is formed. Different flow rates correspond to different deflection angles of the device. , the angle is transmitted to the single-chip microcomputer through the photoelectric encoder, the flow rate is measured by the triangular weir or the flow meter, and the obtained series of values are fitted into a function curve of the angle and the flow rate, and the function curve is determined through repeated experiments, thus, the establishment Angular flow mathematical model; (2) Write the mathematical models of different channels into the single-chip computer program, and compare the measured angle values of the actual channel to be tested, so as to output the flow value of the channel to be tested; The application of realizing the automatic flow measurement of open channels in farmland irrigation areas includes the following contents: Fix the model of an open channel flow measuring device in an irrigation area above the measured channel, put the pendulum into the open channel, and the water flow impacts on the pendulum to make it deflect at a certain angle. Compared with the previously established mathematical model, the channel flow of the open channel in the farmland irrigation area is obtained; the model of the open channel flow measuring device includes a measurement system, a control system, a vertical lifting support, a horizontal displacement platform and a wireless communication module; the measurement system includes a photoelectric Encoder mounting bracket, photoelectric encoder, shaft coupling and swing rod; the photoelectric encoder mounting bracket is connected with the horizontal displacement platform moving left and right, and the photoelectric encoder is an Omron 500 line encoder; the swing rod is a An aluminum alloy solid rod with a diameter of 5 mm and a length of 60 cm; When specifically detecting the angle, the water flow in the channel impacts the pendulum so that the pendulum deflects at a certain angle, and the photoelectric encoder records the angle value through the change of the pulse, and transmits the angle value into the single-chip microcomputer program; the control system includes a single-chip microcomputer, a signal The acquisition and transmission circuit writes the angular flow models of different channels established in the experiment into the single-chip microcomputer. The single-chip microcomputer is also responsible for collecting the width and height signals of the channel, the channel mode, and the control signals of the two stepping motors, and obtains the channel through the angle deflection value. The flow value; The vertical lift bracket includes a channel deck, a lift bracket, a stepper motor and fixing screws; the channel deck fixes the whole device on the channel to be measured with screws and nuts, and the lower end of the lift bracket is welded On the channel deck, the vertical movement of the lifting bracket is controlled by a stepping motor; the horizontal displacement platform includes a detection platform, an infrared rangefinder, a screw, a stepping motor and a level; the horizontal displacement platform is fixed on the detection platform, The rotation of the screw rod is controlled by a stepping motor so that the measurement system is located in the middle of the channel to measure the flow rate; the infrared rangefinder is used to measure the distance in the horizontal direction and send the distance to the single-chip microcomputer to control the movement of the motor , the spirit level is used to detect whether the horizontal displacement platform is level. 2. according to claim 1, the application of a kind of automatic flow measurement mathematical model of open channels in farmland irrigation areas is characterized in that it also includes the following content: the channel clamping groove is fixed on both sides of the channel to be measured with fixing screws, and the whole device is adjusted with reference to the spirit level. Turn on the power, select the channel mode, press the test button, the program drives the stepper motor to drive the screw and the lifting table so that the pendulum is in the best position for testing, and the flow rate of the channel to be tested is displayed on the LCD.