Method for improving AD acquisition precision

Abstract

The invention discloses a method for improving AD acquisition precision, and relates to the technical field of analog signal AD acquisition, by adding a temperature detection circuit and a software correction formula, the current temperature is acquired in real time when AD acquisition equipment works, and the current temperature value is transmitted to an FPGA (Field Programmable Gate Array) through IIC (Inter-Integrated Circuit) communication; and the FPGA compares and judges low temperature, normal temperature or high temperature specified by the current temperature adaptive software in real time, corrects the value acquired by the AD equipment according to a correction formula matched with the current temperature, and outputs and displays the corrected value. The method can bring huge system effects and increase economic benefits only by increasing part of cost, and has the advantages of high interference resistance, small influence of temperature drift and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of analog signal AD acquisition, and in particular to a method for improving AD acquisition accuracy by correcting the influence of temperature drift. Background Art

[0002] With the continuous advancement of modern information technology, the requirements for modern automatic measurement and control are constantly increasing. Among them, analog signal AD acquisition is particularly important because the measurement results will affect the control effect of the entire system. Existing methods for improving AD acquisition accuracy include increasing the resolution of AD acquisition chips, using external dedicated reference voltages for stability and accuracy, adding hardware conditioning circuits and filtering circuits, using low-temperature drift sampling resistors, and software filtering processing. However, in the context of the strict requirements of the use environment in the defense industry, military-grade AD acquisition equipment suffers from distorted signals and errors due to the rapid temperature changes and large value range in the extreme use environment. This problem is caused by the temperature drift of the components in the AD acquisition circuit. Temperature drift can cause errors in the AD acquisition equipment, resulting in a decline in the performance of the measurement and control system.

[0003] Currently, methods to improve the accuracy of AD acquisition include increasing the resolution of the AD acquisition chip, using an external dedicated reference voltage for stability and accuracy, adding hardware conditioning circuits and filtering circuits, using low-temperature drift sampling resistors, and software filtering processing. None of these methods can effectively solve the errors caused by temperature drift of devices in the AD acquisition circuit.

[0004] Improving the resolution of AD acquisition chips: The most direct way to improve the accuracy of AD acquisition equipment is to increase the resolution of the chip. Currently, mainstream AD acquisition chips include 8-bit, 10-bit, 12-bit, 16-bit, and 32-bit chips. Different resolutions are suitable for different scenarios. For example, 8-bit AD acquisition chips are suitable for simple sensor acquisition with low precision requirements, while 32-bit AD acquisition chips are suitable for high-end scientific research equipment and professional audio equipment requiring extremely high-precision measurements. The resolution of an AD acquisition chip refers to the smallest analog quantity it can distinguish. It is usually expressed in binary bits, such as the number of bits in the AD acquisition chip mentioned above. The higher the resolution, the more voltage values the AD acquisition chip can distinguish, and the higher the conversion accuracy.

[0005] Example 1: A 3-bit AD acquisition chip, reference voltage 5V, acquired voltage 2.5V, theoretically calculated acquisition voltage:

[0006] Example 2: An 8-bit AD acquisition chip, with a reference voltage of 5V and an acquired voltage of 2.5V. Theoretically calculated acquisition voltage is:

[0007] From the above two examples, we can see that the higher the resolution of the AD acquisition chip, the higher the acquisition accuracy. However, higher resolution also comes with higher price, greater power consumption, slower response speed, poorer anti-interference ability, and limited application scenarios.

[0008] Adding a hardware conditioning circuit: In practical circuits, the AD acquisition chip pins and analog signal input lines cannot achieve complete conduction and zero resistance. Therefore, a small current flows in the analog signal input lines, causing the actual analog voltage input to the AD acquisition chip to be lower than the voltage being acquired, increasing AD acquisition errors. To address this issue, an operational amplifier conditioning circuit is added to the circuit design to provide isolation and tracking. Because operational amplifiers have high input impedance and low noise, the input impedance of the U53 OPA77 operational amplifier in this circuit can reach 200 GΩ. Compared to this resistance, the resistance of the AD acquisition chip pins and analog signal input lines is a few Ω, effectively approaching zero resistance. As the resistance in the AD acquisition circuit approaches infinity, the current in the AD acquisition circuit approaches zero. The acquired voltage and the voltage at the AD acquisition chip pins are equal, thus avoiding the increase in AD acquisition errors caused by line resistance. However, adding a conditioning circuit cannot effectively address the errors caused by temperature drift of the AD acquisition circuit components.

[0009] The aforementioned methods of increasing the resolution of AD acquisition chips and adding hardware conditioning circuits to improve the accuracy of AD acquisition devices are both significantly affected by temperature. Temperature changes can affect the value of the sampling resistor and the external reference voltage, further affecting the accuracy of the AD sampling device.

[0010] Therefore, how to provide a method for improving AD sampling accuracy and eliminating the influence of temperature drift on acquisition accuracy is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0011] In view of the above problems, the present invention provides a method for improving AD acquisition accuracy to overcome the above problems or at least partially solve the above problems, thereby solving the problem that the accuracy of existing AD acquisition equipment is greatly affected by temperature changes.

[0012] The present invention provides the following solutions:

[0013] A method for improving AD acquisition accuracy, comprising:

[0014] Using AD acquisition circuit to acquire AD acquisition value;

[0015] Use the temperature acquisition circuit to obtain the current temperature value of the AD acquisition circuit;

[0016] Determine the target temperature range in which the current temperature value is located, where the target temperature range includes any one of a low temperature range, a normal temperature range, and a high temperature range;

[0017] Calling a preset correction formula corresponding to the target temperature range;

[0018] Substitute the AD acquisition value into the correction formula to obtain the corrected AD output value.

[0019] Preferably, the AD acquisition circuit includes an AD976 AD acquisition chip circuit.

[0020] Preferably, the temperature acquisition circuit includes a U54 MTS4 temperature acquisition chip, and the U54 MTS4 temperature acquisition chip IIC communicates with a main control device FPGA device.

[0021] Preferably, the low temperature range includes -30°C to 15°C, the normal temperature range includes 15°C to 35°C, and the low temperature range includes 35°C to 60°C.

[0022] Preferably, the correction formula corresponding to the low temperature range is expressed by the following formula:

[0023] y=1x-0.3225

[0024] The correction formula corresponding to the normal temperature range is expressed by the following formula:

[0025] y=1.0007x+0.0087

[0026] The correction formula corresponding to the high temperature range is expressed by the following formula:

[0027] y=1.0001x+0.2574

[0028] Where: y represents the AD output value, and x represents the AD acquisition value.

[0029] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0030] The present invention provides a method for improving AD acquisition accuracy by adding a temperature detection circuit and a software correction formula. This method collects the current temperature in real time while the AD acquisition device is operating, transmits the current temperature value to the FPGA via IIC communication, and then compares and determines in real time whether the current temperature matches the low, normal, or high temperature specified by the software. The FPGA then corrects the value collected by the AD device according to the correction formula that matches the current temperature, and then outputs it for display. This method only requires a small increase in cost, yet can achieve significant system benefits and increase economic efficiency. It also offers advantages such as strong anti-interference and minimal impact from temperature drift.

[0031] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0033] Figure 1 This is a flow chart of a method for improving AD acquisition accuracy provided by an embodiment of the present invention;

[0034] Figure 2 This is a circuit schematic diagram after adding a temperature acquisition circuit according to an embodiment of the present invention;

[0035] Figure 3 This is a graph of voltage errors collected by the AD acquisition device provided by an embodiment of the present invention at low temperature, normal temperature, and high temperature (without adding a temperature detection circuit and software correction formula);

[0036] Figure 4 It is a schematic diagram of the software correction formula of the AD acquisition device provided by an embodiment of the present invention at low temperature, normal temperature and high temperature. DETAILED DESCRIPTION

[0037] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0038] See also Figure 1 , a method for improving AD acquisition accuracy provided by an embodiment of the present invention, such as Figure 1 As shown, the method may include:

[0039] The AD acquisition circuit is used to acquire AD acquisition values; in specific implementation, the embodiment of the present application can provide that the AD acquisition circuit includes an AD976 AD acquisition chip circuit.

[0040] The current temperature value of the AD acquisition circuit is obtained by using the temperature acquisition circuit; in specific implementation, the embodiment of the present application can provide that the temperature acquisition circuit includes a U54 MTS4 temperature acquisition chip, and the U54 MTS4 temperature acquisition chip IIC communicates with the main control device FPGA device.

[0041] Determine the target temperature range in which the current temperature value is located, the target temperature range including any one of a low temperature range, a normal temperature range, and a high temperature range; the range of each temperature zone can be set as needed. For example, in one implementation, the embodiment of the present application can provide that the low temperature range includes -30℃~15℃, the normal temperature range includes 15℃~35℃, and the low temperature range includes 35℃~60℃.

[0042] The preset correction formula corresponding to the target temperature range is called; in specific implementation, the embodiment of the present application can provide that the correction formula corresponding to the low temperature range is expressed by the following formula:

[0043] y=1x-0.3225

[0044] The correction formula corresponding to the normal temperature range is expressed by the following formula:

[0045] y=1.0007x+0.0087

[0046] The correction formula corresponding to the high temperature range is expressed by the following formula:

[0047] y=1.0001x+0.2574

[0048] Where: y represents the AD output value, and x represents the AD acquisition value.

[0049] Substitute the AD acquisition value into the correction formula to obtain the corrected AD output value.

[0050] The method for improving AD acquisition accuracy provided by the present embodiment involves selecting a suitable AD acquisition chip during the circuit design phase. A temperature detection circuit is then added to the existing circuit to monitor the temperature of the AD acquisition circuit in real time. This temperature is then transmitted back to the FPGA, where it is corrected based on the current temperature value, matching it with a pre-set correction formula in the software. This reduces the impact of temperature on the accuracy of the AD acquisition device.

[0051] The following describes in detail the method for improving AD acquisition accuracy provided by this application, taking the AD976 AD acquisition chip circuit with a required accuracy of ±0.2V as an example.

[0052] The main implementation scheme of this method is to add a temperature acquisition circuit to the original AD acquisition circuit, such as Figure 2 The U54MTS4 temperature acquisition chip has a temperature acquisition accuracy of ±0.1°C and communicates with the main control device FPGA device through IIC. Figure 2 shown.

[0053] After the AD acquisition equipment is manufactured and debugged, the FPGA device needs to be calibrated using a standard voltage source at low, normal, and high temperatures. For example, if the AD acquisition value is also recorded at a temperature of 10°C, the calibration formula for the low-temperature range can be determined as follows: y = 1x - 0.3225. This calibrates the AD acquisition value, ultimately obtaining the corrected AD output value.

[0054] Case 1: No temperature detection circuit and software correction formula are added

[0055] After the normal debugging of AD acquisition equipment is completed, the test data at low temperature, normal state and high temperature are shown in Table 1, Table 2 and Figure 3 As shown:

[0056] Table 1

[0057]

[0058]

[0059] Table 2

[0060]

[0061] According to the data in Table 1 and Table 2, Figure 3 It can be seen that the AD equipment calibrated under normal conditions meets the design requirement of AD acquisition accuracy of ±0.2V under normal conditions. However, at low and high temperatures, the error of AD acquisition accuracy will increase due to the influence of temperature. Therefore, the design accuracy requirement of ±0.2V has been exceeded at low and high temperatures.

[0062] Case 2: Adding temperature detection circuit and software correction formula

[0063] After the AD acquisition equipment is produced and debugged, it is necessary to use a standard voltage source to perform software calibration on the AD acquisition equipment at low temperature, normal temperature, and high temperature.

[0064] According to the data collected by AD acquisition equipment at low temperature, normal temperature and high temperature as shown in Table 3, the correction formulas are fitted as follows: Figure 4 As shown:

[0065] Table 3

[0066]

[0067]

[0068] After adding the temperature detection circuit and software correction formula, the data collected by the AD acquisition device at low temperature, normal temperature, and high temperature are shown in Table 4.

[0069]

[0070] The data in Table 4 above show that a temperature detection circuit and software correction formula can be added to correct the error caused by temperature changes in the AD acquisition device for different temperatures.

[0071] In summary, the method for improving AD acquisition accuracy provided by this application adds a temperature detection circuit and a software correction formula. This method collects the current temperature in real time while the AD acquisition device is operating, transmits the current temperature value to the FPGA via IIC communication, and the FPGA compares and determines in real time whether the current temperature matches the low temperature, normal temperature, or high temperature specified by the software. The FPGA then corrects the value collected by the AD device according to the correction formula that matches the current temperature, and then outputs it for display. This method only requires a partial increase in cost to achieve significant system effects and increase economic benefits. It also has the advantages of strong anti-interference and minimal impact from temperature drift.

[0072] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0073] Through the description of the above embodiments, it can be seen that those skilled in the art can clearly understand that the present application can be implemented by means of software plus a necessary general hardware platform. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which can be stored in a storage medium such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in various embodiments or certain parts of the embodiments of the present application.

[0074] Each embodiment in this specification is described in a progressive manner. The same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple. For relevant parts, refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. A person of ordinary skill in the art can understand and implement it without expending creative work.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A method for improving AD acquisition accuracy, characterized in that: include: Using AD acquisition circuit to acquire AD acquisition value; Acquiring the current temperature value of the AD acquisition circuit using a temperature acquisition circuit; Determine the target temperature range in which the current temperature value is located, where the target temperature range includes any one of a low temperature range, a normal temperature range, and a high temperature range; Calling a preset correction formula corresponding to the target temperature range; Substitute the AD acquisition value into the correction formula to obtain the corrected AD output value.

2. The method for improving AD acquisition accuracy according to claim 1, characterized in that: The AD acquisition circuit includes an AD976 AD acquisition chip circuit.

3. The method for improving AD acquisition accuracy according to claim 1, characterized in that: The temperature acquisition circuit includes a U54 MTS4 temperature acquisition chip, and the U54 MTS4 temperature acquisition chip IIC communicates with the main control device FPGA device.

4. The method for improving AD acquisition accuracy according to claim 1, characterized in that: The low temperature range includes -30°C to 15°C, the normal temperature range includes 15°C to 35°C, and the low temperature range includes 35°C to 60°C.

5. The method for improving AD acquisition accuracy according to claim 1, characterized in that: The correction formula corresponding to the low temperature range is expressed by the following formula: y=1x-0.3225 The correction formula corresponding to the normal temperature range is expressed by the following formula: y=1.0007x+0.0087 The correction formula corresponding to the high temperature range is expressed by the following formula: y=1.0001x+0.2574 Where: y represents the AD output value, and x represents the AD acquisition value.

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