In-situ automatic calibration system and method of multi-channel temperature acquisition instrument

Abstract

The invention discloses an in-situ automatic calibration system and method for a multi-channel temperature acquisition instrument. The system comprises a metering port, a change-over switch, an upper computer, a multi-channel change-over switch and a standard signal source. The metering port is connected with the multi-channel change-over switch and is used for calibrating the temperature acquisition instrument; the change-over switch is connected with the acquisition circuit board and is used for switching a measurement mode and a calibration mode, in the measurement mode, the acquisition circuit board is connected with the measurement port, and in the calibration mode, the acquisition circuit board is connected with the metering port; the multi-channel change-over switch performs channel switching under the control of the upper computer, the standard signal source is connected with the multi-channel change-over switch and is used for outputting a preset standard electric signal to the metering port, the acquisition circuit board acquires the electric signal and converts the electric signal into a digital signal, and the master control digital board processes the digital signal and transmits the digital signal to the upper computer. According to the invention, a metering calibration function is added on an original temperature acquisition instrument, so that on-site rapid calibration of the multi-channel temperature acquisition instrument can be realized.

Description

Technical Field

[0001] The present invention belongs to the field of calibration of multi-channel temperature acquisition instruments, and particularly relates to an in-situ automatic calibration system and method for a multi-channel temperature acquisition instrument. Background Art

[0002] The batch measurement of temperature has wide applications in multiple fields. For example, in the tests of aero-engine assemblies or components, it is necessary to simultaneously measure the temperatures at multiple, even thousands of position points in real time, and the measurement ranges and accuracies of each temperature point are different. The accurate measurement of each temperature point is crucial for the reliable operation of aero-engine components and even the evaluation of the overall performance of the engine. Therefore, higher requirements are also put forward for the accuracy of the multi-channel temperature acquisition equipment test.

[0003] After a multi-channel temperature acquisition instrument or similar equipment leaves the factory, with the increase of the service time, its performance indicators will drift to varying degrees, and it is necessary to ensure the accuracy of the equipment test through regular calibration. The relevant specifications require that the calibration interval is at most one year, and the number of calibrations needs to be increased in special cases. Therefore, regular calibration work is an important means to ensure the test performance. At present, the main calibration method in each main host site is to disassemble the acquisition equipment and calibrate it in a laboratory environment. The main disadvantages are that, firstly, the laboratory calibration environment cannot accurately reproduce the actual use environment, and there will be certain errors in the correction coefficients given by the calibration. Secondly, the disassembly and assembly process is complex, the workload of disassembly and assembly is extremely large, which seriously affects the experimental progress, and the risk of equipment damage during repeated disassembly, assembly and transportation is extremely high. This has become the biggest problem restricting the efficient and accurate use of this type of equipment. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems of low test accuracy, high calibration cost, poor timeliness, and easy damage due to repeated disassembly caused by the inability to perform in-situ and automatic calibration of temperature acquisition instruments, especially multi-channel temperature acquisition instruments. The present invention provides an in-situ automatic calibration system and method for a multi-channel temperature acquisition instrument, which realizes the on-site rapid calibration of the multi-channel temperature acquisition instrument by adding a metrological calibration function to the original temperature acquisition instrument.

[0005] To achieve the above purpose, one aspect of the present invention provides an in-situ automatic calibration system for a multi-channel temperature acquisition instrument, including a metrological port, a switching switch, a host computer, a multi-channel switching switch, and a standard signal source;

[0006] The multi-channel temperature acquisition instrument includes an acquisition instrument housing, a measurement port, a thermocouple, an acquisition circuit board, and a main control digital board. The metrological port and the measurement port are arranged on the acquisition instrument housing. The measurement port is connected to the thermocouple for temperature measurement. The metrological port is connected to the multi-channel switching switch through a metrological aviation plug for calibrating the temperature acquisition instrument;

[0007] The switching switch is connected to the acquisition circuit board and is used to switch the measurement mode and the calibration mode under the control of the host computer. In the measurement mode, the acquisition circuit board is connected to the measurement port, and in the calibration mode, the acquisition circuit board is connected to the metering port;

[0008] The multi-channel switching switch is used to perform channel switching under the control of the host computer. The standard signal source is connected to the multi-channel switching switch and is used to output a preset standard electrical signal to the metering port under the control of the host computer. The acquisition circuit board is used to acquire electrical signals and convert them into digital signals, and the main control digital board is used to process the digital signals to obtain measurement values and transmit them to the host computer.

[0009] Preferably, the host computer is used to compare the measurement value with the standard value of the standard electrical signal. When the difference between the two exceeds the error limit, this channel is regarded as the channel to be calibrated;

[0010] The host computer is also used to select the channel to be calibrated for calibration, restore the correction coefficient of the selected channel, output a standard electrical signal through the standard signal source, and calculate a new correction coefficient using the measurement value.

[0011] Preferably, the acquisition circuit board includes an A / D acquisition chip and a memory. The A / D acquisition chip is used to acquire electrical signals, and the memory is used to store electrical signals.

[0012] Another aspect of the present invention provides an in-situ automatic calibration method for a multi-channel temperature acquisition instrument. The in-situ automatic calibration of the multi-channel temperature acquisition instrument is performed using the above system, including:

[0013] The host computer controls the switching switch to enter the calibration mode, controls the standard signal source to output a preset standard electrical signal, and controls the multi-channel switching switch to sequentially switch channels at a set time interval;

[0014] After switching to a certain channel, the electrical signal is converted into a digital signal by the acquisition circuit board. The main control digital board processes the digital signal to obtain a measurement value and transmits it to the host computer. The host computer compares the measurement value with the standard value of the standard electrical signal. When the difference between the two exceeds the error limit, this channel is recorded as the channel to be calibrated;

[0015] The host computer selects the channel to be calibrated for calibration, restores the correction coefficient of this channel, outputs a standard electrical signal through the standard signal source, and calculates a new correction coefficient using the measurement value. And so on until the calibration of all channels to be calibrated is completed.

[0016] Preferably, the method further includes: the host computer stores the new correction coefficient in the memory of the acquisition circuit board, controls the switching switch to switch to the measurement mode, and performs compensation calculation on the acquired measurement signal using the correction coefficient in the memory to obtain the calibrated measurement result.

[0017] Preferably, the host computer calculates the new correction coefficient as follows:

[0018] There are two correction coefficients a and b built in the main control digital board. The host computer restores the correction coefficients by assigning a = 1 and b = 0 to the correction coefficients a and b. During the calibration process, two sets of standard electrical signals are output by the standard signal source respectively, and two sets of measured values are obtained respectively. The new correction coefficients a and b are calculated by the following formula:

[0019] Standard value = (Measured value) × a + b.

[0020] According to the in-situ automatic calibration system and method of the multi-channel temperature collector in the above aspect of the present invention, the on-site rapid calibration of the multi-channel temperature collector can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts:

[0022] Figure 1 is a schematic structural diagram of an in-situ automatic calibration system of a multi-channel temperature collector according to an embodiment of the present invention;

[0023] Figure 2 is a flowchart of an in-situ automatic calibration method of a multi-channel temperature collector according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] An embodiment of the present invention provides an in-situ automatic calibration system for a multi-channel temperature collector, as Figure 1 shown, in order to realize the in-situ and automatic calibration of each channel of the multi-channel temperature collector, for the multi-channel temperature collector, by adding a switching switch in front of the acquisition circuit board, the acquisition circuit board has two switchable input routes. One of the routes corresponds to the measurement mode (see Figure 1The thin solid line part), with the thermocouple as the input end, one end is connected to multiple isothermal plate terminals of the temperature acquisition instrument, and the other end is connected to the measurement port. Switching to this mode enables normal temperature acquisition; the other route (see Figure 1 The dotted line part) corresponds to the calibration mode. The input end is connected to the metering port added on the acquisition instrument housing. Switching to this mode enables entering the calibration mode. The multi-channel switch is connected to the metering port through a metering aviation plug. The metering aviation plug is a general aviation plug, including an aviation plug socket and an aviation plug. The aviation plug socket part is connected to the metering port, and the aviation plug part is externally connected to the multi-channel switch. The selection between the two modes is achieved by the upper computer controlling the changeover switch. This design ensures that the signal paths of the calibration mode and the measurement mode are completely independent, avoiding mutual interference. Among them, Figure 1 The thin solid line is the test process of the measurement mode, the thin dotted line is the test process of the metering mode, and the thick solid line is the general calculation and processing process for both.

[0026] In Figure 1 the multi-channel temperature acquisition instrument includes an acquisition instrument housing, a measurement port, a thermocouple, an acquisition circuit board, and a main control digital board. The in-situ automatic calibration system of the embodiment of the present invention includes a metering port, a changeover switch, an upper computer, a multi-channel switch, and a standard signal source. The metering port and the measurement port are arranged on the acquisition instrument housing. The measurement port is connected to the thermocouple for temperature measurement. The metering port is connected to the multi-channel switch through a metering aviation plug for calibrating the temperature acquisition instrument. The changeover switch is connected to the acquisition circuit board for switching between the measurement mode and the calibration mode under the control of the upper computer. In the measurement mode, the acquisition circuit board is connected to the measurement port. In the calibration mode, the acquisition circuit board is connected to the metering port.

[0027] The multi-channel switch is used to achieve arbitrary channel switching. One end is connected to the metering port on the temperature acquisition instrument through a cable via the metering aviation plug, and the other end is connected to the standard signal source; the upper computer can both control the standard signal source to send a preset standard electrical signal and control the multi-channel switch to switch channels.

[0028] The acquisition circuit board is used to acquire and store the measured electrical signals, and send the stored data to the main control digital board for calculation and processing to obtain the measurement value and transmit it to the upper computer, and the upper computer performs data display. The acquisition circuit board includes an A / D acquisition chip and a memory. The A / D acquisition chip is used to acquire the measured electrical signals, and the memory is used to store the electrical signals.

[0029] To calibrate each channel of the multi-channel temperature collector, the host computer compares the measured value with the standard value of the standard electrical signal. When the difference between the two exceeds the error limit, the channel is regarded as the channel to be calibrated, and then the channel to be calibrated is selected for calibration. First, the correction coefficient of the selected channel is restored, and then the standard electrical signal is output by the standard signal source, and the new correction coefficient is calculated using the obtained measured value.

[0030] The embodiment of the present invention also provides an in-situ automatic calibration method for a multi-channel temperature collector, which uses the in-situ automatic calibration system of the above embodiment of the present invention to perform in-situ automatic calibration of the multi-channel temperature collector. As Figure 2 shown, the in-situ automatic calibration method of the embodiment of the present invention includes a preparation stage, a verification process, and a calibration process.

[0031] In the preparation stage, the host computer first establishes a communication connection with the in-situ automatic calibration system, completes the status check and calibration parameter configuration of the multi-channel temperature collector, including parameters such as the standard electrical signal value output by the standard signal source and the time interval for channel switching. Then, data acquisition is started.

[0032] In the verification process, the host computer controls the switching switch to enter the calibration mode. Subsequently, the host computer controls the standard signal source to output a preset standard electrical signal value, and at the same time controls the multi-channel switch to sequentially switch channels at the set time interval. After switching to a certain channel, the electrical signal is converted into a digital signal by the acquisition circuit board, and the main control digital board processes and calculates the digital signal to obtain the measured value and then transmits it to the host computer. The host computer compares the measured value with the standard value. When the difference exceeds the error limit, the channel is recorded as the channel to be calibrated. The host computer controls the multi-channel switch to sequentially switch channels at the set time interval until the verification of all channels is completed.

[0033] In the calibration process, the host computer preferentially selects the channels with larger errors for calibration. First, the correction coefficient of the channel is restored. In one embodiment, two correction coefficients a and b are built into the main control digital board for calibrating the measured voltage signal:

[0034] Calibrated voltage value or standard voltage signal = (measured voltage value) × a + b (1)

[0035] At the beginning of calibration, first restore the correction coefficient of the channel and assign values of a = 1 and b = 0 to it. During calibration, the standard signal source outputs two groups of standard voltage signals (such as 10 mV and 70 mV) respectively, two groups of data are measured respectively, and then the new correction coefficients a and b are calculated through formula (1) and stored in the memory of the acquisition circuit board. After verifying that the corrected measured value meets the requirements, the host computer updates the channel parameters and displays the measurement result data, and so on until all channels to be calibrated are completed.

[0036] Finally, the host computer controls the change-over switch to the measurement mode through the main control board. During the normal measurement process, the collected measured signals will be compensated and calculated using the correction factors in the memory, thereby ensuring that the display result is the accurate measurement result of the multi-channel temperature collector after calibration.

[0037] In summary, the in-situ automatic calibration system and method of the multi-channel temperature collector according to the embodiments of the present invention can realize the in-situ and automatic calibration of each channel, and have the following beneficial effects:

[0038] 1. By adding a change-over switch in front of the acquisition circuit board and combining with the metering port added to the housing, a switchable and external input port is added to the acquisition circuit board, providing the hardware possibility for in-situ calibration;

[0039] 2. Through the calibration module composed of a standard signal source and a multi-channel change-over switch, etc., combined with the host computer, the individual automatic calibration of each channel can be realized, and the correction value of each channel is given, which not only avoids the interference and influence generated between each other during the overall calibration after the series connection of each channel, but also ensures the timeliness and easy operation of the individual calibration of each channel.

[0040] Only some exemplary embodiments of the present invention have been described by way of illustration above. Without doubt, for those of ordinary skill in the art, the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the protection scope of the claims of the present invention.

Claims

1. An in-situ automatic calibration system for a multi-channel temperature acquisition instrument, characterized in that: Including metering port, switching switch, host computer, multi-channel conversion switch, standard signal source; The multi-channel temperature collector includes a collector housing, a measuring port, a thermocouple, a collection circuit board and a main control digital board. The metering port and the measuring port are arranged on the collector housing. The measuring port is connected to the thermocouple for temperature measurement. The metering port is connected to the multi-channel conversion switch through the metering aviation plug for calibration of the temperature collector. The switch is connected to the acquisition circuit board and is used to switch between the measurement mode and the calibration mode under the control of the host computer. In the measurement mode, the acquisition circuit board is connected to the measurement port, and in the calibration mode, the acquisition circuit board is connected to the metering port; The multi-channel conversion switch is used to switch channels under the control of the host computer. The standard signal source is connected to the multi-channel conversion switch to output a preset standard electrical signal to the metering port under the control of the host computer. The acquisition circuit board is used to collect electrical signals and convert them into digital signals. The main control digital board is used to process the digital signals to obtain measurement values ​​and transmit them to the host computer.

2. The system according to claim 1, characterized in that The host computer is used to compare the measured value with the standard value of the standard electrical signal. When the difference between the two exceeds the error limit, the channel is used as the channel to be calibrated; The host computer is also used to select the channel to be calibrated for calibration, restore the correction coefficient of the selected channel, output the standard electrical signal through the standard signal source, and calculate the new correction coefficient using the measured value.

3. The system according to claim 1 or 2, characterized in that: The acquisition circuit board includes an A / D acquisition chip and a memory. The A / D acquisition chip is used to acquire electrical signals, and the memory is used to store electrical signals.

4. An in-situ automatic calibration method for a multi-channel temperature acquisition instrument, characterized in that: Using the system described in any one of claims 1 to 3 to perform in-situ automatic calibration of a multi-channel temperature collector, comprising: The host computer controls the switching switch to enter the calibration mode, controls the standard signal source to output a preset standard electrical signal, and controls the multi-channel switching switch to switch channels in sequence according to the set time interval; After switching to a certain channel, the electrical signal is converted into a digital signal by the acquisition circuit board. The main control digital board processes the digital signal to obtain the measured value and transmits it to the host computer. The host computer compares the measured value with the standard value of the standard electrical signal. When the difference between the two exceeds the error limit, the channel is recorded as the channel to be calibrated. The host computer selects the channel to be calibrated for calibration, restores the correction coefficient of the channel, outputs the standard electrical signal through the standard signal source, calculates the new correction coefficient using the measured value, and so on, until the calibration of all the channels to be calibrated is completed.

5. The method according to claim 4, characterized in that Also includes: The host computer stores the new correction coefficient in the memory of the acquisition circuit board, controls the switch to switch to the measurement mode, uses the correction coefficient in the memory to perform compensation calculation on the collected measurement signal, and obtains the calibrated measurement result.

6. The method according to claim 4 or 5, characterized in that The host computer calculates the new correction coefficient as follows: The main control digital board has two built-in correction coefficients a and b. The host computer restores the correction coefficients by assigning them a=1 and b=0. During the calibration process, two groups of standard electrical signals are output through the standard signal source, and two groups of measurement values ​​are obtained respectively. The new correction coefficients a and b are calculated by the following formula: Standard value = (measured value) × a + b.

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