CN104132710A - Water level flow sensor, water level flow monitoring system and water level flow monitoring method - Google Patents

Abstract

The present invention aims to provide a water level and flow sensor, a water level and flow monitoring system and a water level and flow monitoring method that can accurately and quickly measure water level and flow, have a long service life and work stably. The detection rod, the multi-channel voltage comparison circuit connected to the contact, the multiple-channel selection circuit correspondingly connected to the multiple-channel voltage comparison circuit, the main control circuit receiving the output signal of the multi-channel selection circuit, and the data transmission output connected to the main control circuit circuit; the water level flow monitoring system includes a host computer, the above-mentioned water level flow sensor, and the water level flow sensor is connected to the host computer via an RS-232/RS-485 converter. Continuously monitor the water level and flow in the channel, and display the results on the digital tube and the upper computer.

Description

Water level flow sensor, water level flow monitoring system and water level flow monitoring method

technical field

The invention relates to the field of water level and flow monitoring, in particular to a water level and flow sensor for detecting flow, a water level and flow monitoring system and a water level and flow monitoring method. the

Background technique

At present, my country is a country with a large water shortage, and agricultural irrigation water accounts for more than 60% of my country's total water consumption. Therefore, realizing precise irrigation for agriculture to save agricultural water resources is a very urgent requirement for farmland irrigation. A major move for continued development. the

At present, water measurement methods commonly used in irrigation areas include flow meter water measurement, hydraulic building water measurement, special water measurement equipment water measurement, etc. Among them, flow meter water measurement is mainly based on the flow velocity area method. Although the measurement accuracy is high, the price Expensive, cumbersome to operate, and inconvenient for large-scale promotion. For irrigation channels, this method is generally used for the calibration of water level and flow relationship and the monitoring of water volume in important sections. Although it is simple and easy to use hydraulic structures to measure water, the error is relatively large, and the measurement accuracy is not guaranteed due to the aging, deformation, and erosion of hydraulic structures. Using special water measuring equipment and facilities to measure water, the construction cost of the facilities is high, and the water flow in the channel has a great impact on the observation accuracy, such as sedimentation, floating objects, etc.; and the calibration of the water level and flow is a large workload, which is not easy to implement Automatic transmission of numerical and graphic information. Therefore, my country's irrigation areas urgently need to combine the actual conditions of irrigation channels or rivers to develop economical, practical, affordable water level and flow measurement and monitoring equipment that facilitates digital information transmission. the

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, to meet the needs of reality, and to provide a water level and flow sensor, a water level and flow monitoring system and a water level and flow monitoring method that can accurately and quickly measure the water level and flow, have a long service life and work stably . the

In order to realize the purpose of the present invention, this adopted technical scheme is:

A water level flow sensor is designed, comprising a water level detection rod, a certain number of contacts are arranged on the water level detection rod, and a multi-channel voltage comparison circuit correspondingly connected to the contacts, and a comparison circuit with the multi-channel voltage The multiplex circuit connected to the corresponding circuit, the main control circuit for receiving the output signal of the multiplex circuit and outputting the flow signal, for receiving the flow signal output by the main control circuit, and transmitting the flow signal to the upper The data transmission output circuit of the machine.

The main control circuit includes a micro-control chip, a clock circuit, a reset circuit and a JTAG interface circuit all correspondingly connected to the micro-control chip, and the micro-control chip is any one of MSP430 series single-chip microcomputers. the

The clock circuit includes a low-frequency oscillator circuit and a high-frequency oscillator circuit, the low-frequency oscillator circuit includes a low-frequency crystal oscillator of 10.768KHz to 32.768KHz, and the high-frequency oscillator circuit includes a high-frequency crystal oscillator of 450KHz to 8MHz; The multiplexing circuit includes a multiplexer ADG732; the data transmission output circuit includes a MAX3232 chip correspondingly connected to the microcontroller chip, and an RS-232 interface connected correspondingly to the MAX3232 chip; the reset circuit is an R-C reset circuit. the

The water level detection rod includes a housing, and the contacts are arranged on the outer surface of the housing at equal intervals of 0.5-5.0 mm along the axis direction. the

The contacts are stainless steel screws, and the caps on the stainless steel screws are arranged on the outer surface of the housing. the

The multi-channel voltage comparison circuit, the multi-channel selection circuit, the micro-control chip and the clock circuit are all located on the circuit board, and the circuit board is arranged in the inner cavity of the housing and sealed by an epoxy tree. the

The water level flow sensor also includes a digital display tube group correspondingly connected with the micro-control chip and used for displaying flow information. the

A water level and flow monitoring system includes a host computer and the above-mentioned water level and flow sensor; the water level and flow sensor is correspondingly connected to the host computer via an RS-232/RS-485 converter. the

A method for monitoring water level and flow using the above-mentioned water level and flow monitoring system, comprising the steps of:

① Arrange the water level detection rod of the water level flow sensor at the corresponding position of the channel or river to be detected according to the conventional method;

② The multi-channel voltage comparison circuit of the water level flow sensor collects the voltage between different contacts and compares it with the reference voltage, and then outputs the result to the multi-channel selection circuit;

③ The multi-channel selection circuit encodes the input voltage signal and inputs it to the main control circuit of the water level flow sensor;

④ The main control circuit processes the encoded signal input into it into a water depth signal R, and substitutes the water depth signal R into the following formula to calculate the flow Q at the corresponding position of the channel or river to be detected:

(1);

In formula (1), A is the cross-sectional area of the channel; n is the roughness of the channel; i is the longitudinal slope of the channel; among them, when the water level and flow sensor is fixed at the location, the cross-sectional area A of the channel and the water depth signal R are in the form of The corresponding functional relationship, so only need to measure the corresponding water depth signal, you can know the flow of the corresponding detection point;

⑤ The main control circuit outputs the obtained flow Q to the upper computer through the RS-232/RS-485 converter, and outputs it to the display terminal for display.

The beneficial effects of the present invention are:

1. The water level and flow sensor has high measurement accuracy, stability and reliability. By measuring the voltage values of different contacts of the water level detection rod and comparing them, the water level and flow information can be displayed on the display terminal in real time after analysis and processing by the micro-control chip. , which is convenient for the staff to observe intuitively, and secondly, the output information can be transmitted to the host computer through the data transmission output circuit in the sensor.

2. The water level detecting rod of the present invention is made of stainless steel screw as the contact outside the housing, and the cavity inside the housing and the circuit board are sealed by epoxy resin. When the sensor enters the water, the water level can be made first The detection rod has good corrosion resistance and sealing performance, which can prevent water body from causing corrosion and other damage to the water level detection rod and its internal circuit, and increase its service life. the

3. When the flow monitoring system of the present invention monitors the flow of the water body, it is not affected by factors such as the outdoor environment, and can output the flow signal to the indoor host computer in real time, so as to monitor the flow information conveniently and quickly; it is convenient for the real-time observation of the operator, Resources such as manpower and material resources are saved; and the system is easy to operate, use and maintain, has low manufacturing costs, and is easy to popularize and use. the

4. While outputting the flow signal, the flow monitoring system of the present invention can also output the water depth R to the display terminal and the host computer in real time, so that the operator can know the relevant parameters. the

Description of drawings

Fig. 1 is a schematic diagram of the main structure of the water level detection rod in the present invention;

Fig. 2 is a schematic diagram of the circuit principle of the water level flow sensor of the present invention;

Fig. 3 is JTAG interface, reset circuit, clock circuit and connect schematic diagram with micro-control chip circuit among the present invention;

Fig. 4 is a schematic diagram of a data transmission output circuit in the present invention;

In Figure 1: 1. Wire; 2. Circuit board; 3. Contact; 4. Shell; 5. Epoxy resin.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the present invention is further described:

Embodiment 1: A water level flow sensor, referring to Figures 1 to 4, includes a water level detection rod, the water level detection rod includes a housing 4, and the outer surface of the housing 4 along its axis direction is provided with 2.0mm equidistant distances A plurality of contacts 3 for connecting with an external circuit (circuit board 2 ), the contacts 3 are stainless steel screws, and the screw caps on the stainless steel screws are arranged on the outer surface of the housing 4 , as shown in FIG. 1 . The water level flow sensor also includes a multi-way voltage comparison circuit correspondingly connected to the above-mentioned contact 3, a multi-way selection circuit correspondingly connected to the multi-way voltage comparison circuit and used to receive the output voltage of the multi-way voltage comparison circuit, and a multi-way selection circuit for receiving the output voltage of the multi-way voltage comparison circuit. The main control circuit that selects the output signal of the circuit and outputs the water level signal, and the data transmission output circuit that is used to receive the flow signal output by the main control circuit and transmit the flow signal. The above-mentioned multiplexing circuit includes a multiplexer ADG732. The main control circuit includes MSP430F149 single-chip microcomputer, clock circuit, reset circuit and JTAG interface circuit which are all connected with MSP430F149 single-chip microcomputer. , 3, 5, 7, 9, 13 pins are respectively connected with the TD0, TDI, TMS, TCK, DVss, RST pins of the MSP430F149 microcontroller; the clock circuit includes a low-frequency oscillation circuit, a high-frequency oscillation circuit, and a low-frequency oscillation circuit includes 32.768KHz The low-frequency crystal oscillator Y2 is connected to the XIN and XOUTI/TCLK pins of the MSP430F149 microcontroller. The high-frequency oscillator circuit includes an 8MHz high-frequency crystal oscillator Y1, which forms a series circuit with the high-frequency crystal oscillator Y1. Capacitors C2 and C3, the two ends of the high-frequency crystal oscillator Y1 are correspondingly connected with the XT2IN and XT2OUT pins of the MSP430F149 microcontroller. The high-frequency crystal oscillator Y1 and the low-frequency crystal oscillator Y2 provide 32.768KHz and 8MHz clocks for the MSP430F149 microcontroller respectively; the low-frequency crystal oscillator Y2 can meet the requirements of low power consumption, and the 8MHz high-frequency oscillator Y1 can be used when not in use. It is turned off to reduce power consumption. The data transmission output circuit includes the MAX3232 chip connected to the UTXDO and URXDO pins of the MSP430F149 microcontroller, and the RS-232 interface connected to the MAX3232 chip; the RS-232 interface is mainly used to establish a communication connection with the host computer, and realize the data Transmission to host computer. The reset circuit is an R-C reset circuit, including a key S in series, a resistor R1, and a capacitor C1 connected in parallel with the key S and resistor R1. The key S and the capacitor C1 are connected in parallel to the RST pin in the MSP430F149 microcontroller. The water level flow sensor also includes a digital display tube group correspondingly connected with the MSP430F149 microcontroller and used for displaying water level information. Through the display of the digital display tube group, the flow information detected and processed by the water level flow sensor can be displayed on the digital display tube group. It is convenient for intuitive observation. The above-mentioned multi-channel voltage comparison circuit, multi-channel selection circuit, MSP430F149 single-chip microcomputer, and clock circuit are all printed on the circuit board 2, and the circuit board 2 is arranged in the inner cavity of the housing 4, and it is sealed by epoxy resin 5 , used to prevent water from entering it and causing damage to the circuit board. The detected data is transmitted through the wire 1. After its multi-channel voltage comparison circuit collects the water level signal, it compares with the reference voltage, and its output voltage (that is, the comparison result) enters the input channel of the multiplexer ADG732, and the data output channel of the multiplexer ADG732 corresponds to the MSP430F149 microcontroller connect. The above-mentioned multiplexer ADG732 can be encoded into 32 addresses according to the 5-bit binary address lines A0, A1, A2, A3 and A4 on it, and the five-bit address selection terminals on the multiplexer ADG732 are sequentially connected with the MSP430F149 microcontroller The P6.3, P6.4, P6.5, P6.6 and P6.7 pins are connected, so that the MCU can change these IO ports (P6.3, P6.4, P6.5, P6.6, P6.7 pin) input, you can change the strobe address of the ADG732, and switch one of the 32 inputs to the common output. The control terminals CS, WR and EN of the multiplexer ADG732 are connected to P3.0, P3.1 and P3.2 of the MSP430F149 microcontroller in turn, and the microcontroller changes the input of P3.0, P3.1 and P3.2 pins You can change the working state of ADG732.

The present invention also relates to a water level and flow monitoring system, which includes a host computer and the above-mentioned water level and flow sensor; the water level and flow sensor is correspondingly connected to the host computer via an RS-232/RS-485 converter. the

The present invention also relates to a method for monitoring water level and flow using the above-mentioned water level and flow monitoring system, comprising the following steps:

① Arrange the water level detection rod of the water level flow sensor at the corresponding position of the channel or river to be detected according to the conventional method;

② The multi-channel voltage comparison circuit of the water level flow sensor collects the voltage between different contacts and compares it with the reference voltage, and then outputs the result to the multi-channel selection circuit;

③ The multi-channel selection circuit encodes the input voltage signal and inputs it to the main control circuit of the water level flow sensor;

④ The main control circuit processes the encoded signal input into it into a water depth signal R, and substitutes the water depth signal R into the following formula to calculate the flow Q at the corresponding position of the channel or river to be detected:

(1)

Formula (1) and calculate its flow Q; in the test, A is the cross-sectional area of the channel; n is the roughness of the channel; The cross-sectional area A has a corresponding functional relationship with the water depth signal R, so the flow rate at the corresponding detection point can be known only by measuring the corresponding water depth signal;

⑤ The main control circuit outputs the obtained flow Q to the upper computer through the RS-232/RS-485 converter, and outputs it to the digital tube group (display terminal) for display.

Described formula (1) comprises and obtains by following steps:

(1) Determine the channel roughness n, cross-sectional area A, and longitudinal slope i of the channel.

(2) Substitute the cross-sectional area A and water depth R of the channel into the uniform flow formula (2):

(2),

Among them, C is the talent coefficient;

(3) Substituting the Manning formula into the uniform flow formula (2), we can get:

.

It can be seen from this formula that after the shape, size, longitudinal slope and roughness of the channel section are determined, the water flow in the channel is only a function of the water depth R. Therefore, as long as the water depth R in the channel can be measured, the water flow in the channel can be calculated. Assume that the channel is a circular pipe with a circular cross-section. After the circular pipe is determined, its shape, size, longitudinal slope and roughness can be determined. , where D is the diameter of the circular pipe, is full angle; and , it can be seen from this formula that after the circular pipe is determined, its D can be directly obtained, and the water depth can be measured by the water level flow sensor, so the formula full angle in It can be concluded that the cross-sectional area of water can be obtained; therefore, the flow rate Q can be obtained. Another example is assuming that the cross-section of the channel is rectangular, its upper and lower width is d, and its height is L, A=d(LR); from this formula, it can be concluded that after the rectangular channel is determined, its upper and lower width and height can be determined, so its A It is only a function of R, so it is only necessary to measure the water depth R to obtain the cross-sectional area A of the water, so The size of Q can be obtained only by measuring the water depth R.

The water level and flow sensor, the water level and flow monitoring system of the present invention, and the water level and flow detection method combined with the two have the following advantages:

①The water level flow sensor only needs 3.3VDC lithium battery for power supply, and the power consumption is low.

②When in use, the current of the water level flow sensor from the inactive state to the low power mode sleep state is only 0.7μA. the

③ When the water level flow sensor is interrupted externally, it only takes 6 μS to enter the active state from the dormant state. the

The present invention selects the East Main Canal of the People's Shengli Canal Irrigation Area in Henan Province in the lower reaches of the Yellow River as a test point, and the canal is lined with concrete. The present invention is compared with the measured flow rate observed by the flow meter (the flow meter is a relatively accurate instrument for detecting flow velocity at present), and the test data and error analysis thereof are shown in Table 1. the

Table 1 Flow Monitoring Comparison

From the observation results in the above table, it can be seen that the maximum relative error between the flow measurement value of the present invention and the actual flow measurement value observed by the current meter is 2.89%. At the same time, it provides technical support for realizing the automation of water level and flow observation of farmland irrigation channels in my country and the automatic transmission of digital information and graphics, and provides conditions for realizing scientific and precise irrigation in irrigation areas, realizing water conservation, and improving the level of scientific management.

Finally, it is pointed out that this embodiment discloses a preferred embodiment, but it is not limited thereto. Those skilled in the art can easily make different extensions and changes based on the above embodiments, but as long as they do not depart from the present invention spirit, all within the protection scope of the present invention. the

Claims (9)

1. A water level flow sensor, comprising a water level detection rod, is characterized in that: a certain number of contacts are arranged on the water level detection rod, and also includes a multi-channel voltage comparator circuit correspondingly connected to the contacts, a multi-way selection circuit correspondingly connected to the multi-way voltage comparison circuit, A main control circuit for receiving the output signal of the multiplex circuit and outputting the flow signal, It is used to receive the flow signal output by the main control circuit and transmit the flow signal to the data transmission output circuit of the upper computer. 2. The water level flow sensor according to claim 1, wherein the main control circuit includes a micro-control chip, a clock circuit, a reset circuit and a JTAG interface circuit that are all correspondingly connected to the micro-control chip, and the micro-control chip The control chip is any one of the MSP430 series microcontrollers. 3. The water level flow sensor according to claim 2, characterized in that: the clock circuit includes a low-frequency oscillation circuit and a high-frequency oscillation circuit, and the low-frequency oscillation circuit includes a low-frequency crystal oscillator of 10.768KHz to 32.768KHz, and the The high-frequency oscillation circuit includes a 450KHz-8MHz high-frequency crystal oscillator; the multiplexer circuit includes a multiplexer ADG732; the data transmission output circuit includes a MAX3232 chip correspondingly connected to the micro-control chip, and The MAX3232 chip corresponds to the connected RS-232 interface; the reset circuit is an R-C reset circuit. 4 . The water level flow sensor according to claim 3 , wherein the water level detection rod comprises a housing, and the contacts are arranged on the outer surface of the housing at equal intervals of 0.5-5.0 mm along the axis thereof. 5. The water level flow sensor according to claim 4, characterized in that: said multi-channel voltage comparison circuit, multi-channel selection circuit, micro-control chip, and clock circuit are all located on a circuit board, and said circuit board is arranged on said The inner cavity of the housing is sealed and wrapped by epoxy resin. 6 . The water level flow sensor according to claim 5 , wherein the contact is a stainless steel screw, and the screw head on the stainless steel screw is arranged on the outer surface of the housing. 7 . 7. The water level and flow sensor according to claim 2, characterized in that: the water level and flow sensor further comprises a digital display tube group correspondingly connected to the micro-control chip and used for displaying flow information. 8. A water level and flow monitoring system, characterized by comprising a host computer and the water level and flow sensor according to claim 1; the water level and flow sensor is correspondingly connected to the host computer via an RS-232/RS-485 converter. 9. A method utilizing the water level and flow monitoring system described in claim 8 to carry out water level and flow monitoring, is characterized in that, comprises the steps: The water level detection rod of the water level flow sensor is arranged in the corresponding position of the channel or river to be detected according to the conventional method; The multi-channel voltage comparison circuit of the water level flow sensor collects the voltage between different contacts and compares it with the reference voltage, and then outputs the result to the multi-channel selection circuit; The multiplex circuit encodes the input voltage signal and inputs it to the main control circuit of the water level flow sensor; The main control circuit processes the encoded signal input into it into a water depth signal R, and substitutes the water depth signal R into the following formula to calculate the flow Q at the corresponding position of the channel or river to be detected: (1); In formula (1), A is the cross-sectional area of the channel; n is the roughness of the channel; i is the longitudinal slope of the channel; The main control circuit outputs the obtained flow Q to the upper computer through the RS-232/RS-485 converter, and outputs it to the display terminal for display.