Demodulation device and method of linear displacement sensor

Abstract

The invention provides a demodulation device and method for a linear displacement sensor, and the device comprises a demodulation module and a negative feedback excitation module. The demodulation module is connected with the negative feedback excitation module, the demodulation module is used for demodulating an output signal of the linear displacement sensor and outputting a signal demodulation result, and the negative feedback excitation module is used for generating a negative feedback excitation signal based on the output signal of the linear displacement sensor. The negative feedback excitation signal acts on an excitation signal for controlling an excitation coil of the linear displacement sensor. The problem of poor linearity caused by a manufacturing process of the linear displacement sensor can be solved by utilizing the negative feedback excitation signal, the linearity of the linear displacement sensor is improved, and the precision of the linear displacement sensor is further improved.

Description

Technical Field

[0001] The present application relates to the field of sensor demodulation, and in particular, to a demodulation device and method for a linear displacement sensor. Background Art

[0002] The linear displacement sensor is a differential transformer type displacement sensor with many advantages such as simple and reliable structure, long service life, high sensitivity, strong environmental adaptability, etc. It is used to convert the measured physical quantity of displacement change into electrical quantity. When using a linear displacement sensor, it is necessary to demodulate the detection output signal of the linear displacement sensor. On the other hand, the linearity of the linear displacement sensor refers to the degree of linear relationship between the output signal of the linear displacement sensor and the input displacement. Generally speaking, the better the linearity, the higher the accuracy of the linear displacement sensor.

[0003] However, in the production environment, defects in the production process and manufacturing principle of the linear displacement sensor will cause the linearity of the produced linear displacement sensor to fail to meet the requirements of the specified application scenario. On the other hand, in the demodulation process of the linear displacement sensor, the prior art does not process the linear displacement sensor whose linearity does not meet the requirements of the specified application scenario, that is, the demodulation of the linear displacement sensor cannot correct the low linearity of the linear displacement sensor caused by defects in the production process and manufacturing principle. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a demodulation device and method for a linear displacement sensor, so as to overcome the problem of poor linearity caused by the manufacturing process of the linear displacement sensor, improve the linearity of the linear displacement sensor, and further improve the accuracy of the linear displacement sensor.

[0005] In a first aspect, the present invention provides a demodulation device for a linear displacement sensor, the demodulation device comprising a demodulation module and a negative feedback excitation module;

[0006] The demodulation module is connected to the negative feedback excitation module, the demodulation module is used to demodulate the output signal of the linear displacement sensor and output the signal demodulation result, the negative feedback excitation module is used to generate a negative feedback excitation signal based on the output signal of the linear displacement sensor, and the negative feedback excitation signal acts on the excitation signal of the excitation coil that controls the linear displacement sensor.

[0007] In the present application, the demodulation device of the linear displacement sensor includes a demodulation module for realizing the demodulation function, and further includes a negative feedback excitation module. Therefore, while realizing the demodulation function, the negative feedback excitation signal generated by the negative feedback excitation module can also act on the excitation signal of the excitation coil that controls the linear displacement sensor, thereby realizing negative feedback adjustment of the linear displacement sensor, wherein the negative feedback adjustment can improve the linearity of the linear displacement sensor, overcome the problem of poor linearity caused by the manufacturing process of the linear displacement sensor, and thereby improve the accuracy of the linear displacement sensor.

[0008] In an optional implementation, the demodulation device is an analog circuit.

[0009] This optional implementation can use analog circuits to design a demodulation device, so that the demodulation device based on analog circuit design can overcome the problems of high analog-to-digital conversion processing delay, complexity and low reliability compared to the demodulation device designed with analog-to-digital conversion circuits, and thus has a higher response speed and the advantages of simplicity and high reliability.

[0010] In an optional embodiment, the negative feedback excitation module includes an adder and a signal generator, wherein the input end of the adder is used to connect to the signal demodulated by the secondary coil of the linear displacement sensor, the signal generator is electrically connected to the output end of the adder, the adder is used to perform signal addition operation on the output signal of the linear displacement sensor, and the signal generator is used to generate the negative feedback excitation signal according to the addition operation result of the adder.

[0011] This optional implementation can perform signal addition operation on the output signals of the linear displacement sensor through an adder, and then generate the negative feedback excitation signal according to the addition operation result of the adder.

[0012] In an optional implementation, the negative feedback excitation signal generated by the signal generator is a square wave signal.

[0013] This optional implementation can use a square wave signal as a negative feedback excitation signal, wherein the square wave signal has the advantages of simple circuit implementation and strong anti-interference ability.

[0014] In an optional implementation, the negative feedback excitation module further includes a signal generator power supply, wherein the signal generator power supply is electrically connected to the signal generator for providing power to the signal generator.

[0015] This optional implementation may provide power to the signal generator via a signal generator power supply.

[0016] In an optional embodiment, the negative feedback excitation module also includes a power supply step-down circuit, wherein the output end of the power supply step-down circuit is electrically connected to the power supply of the signal generator, and the input end of the power supply step-down circuit is connected to a 12V DC power supply for converting the 12V voltage into the operating voltage of the signal generator.

[0017] In an optional embodiment, the demodulation module includes a full-wave rectifier filter circuit and a subtractor, wherein the subtractor is electrically connected to the full-wave rectifier filter circuit, the full-wave rectifier filter circuit is used to perform shaping and filtering on the output signal of the linear displacement sensor, and the subtractor is used to perform subtraction operation on the shaped and filtered signal to obtain the demodulation result.

[0018] This optional implementation can perform shaping and filtering on the output signal of the linear displacement sensor through a full-wave rectification and filtering circuit.

[0019] In an optional implementation, the demodulation module further includes an output driver, the output driver is electrically connected to the subtractor, and the output driver is used to reduce output impedance.

[0020] This optional implementation can reduce the output impedance of the demodulation device through output driving.

[0021] In an optional implementation, the demodulation module and the negative feedback excitation module are on the same double-sided SMD circuit board.

[0022] This optional implementation can integrate the demodulation module and the negative feedback excitation module on the same double-sided SMD circuit board, wherein the double-sided SMD circuit board has the advantages of high integration and high welding quality reliability.

[0023] In a second aspect, the present invention provides a demodulation method for a linear displacement sensor, the method being applied to a demodulation device as described in any one of the aforementioned embodiments, the method comprising:

[0024] Obtaining the output signal of the linear displacement sensor;

[0025] Demodulating the output signal of the linear displacement sensor;

[0026] A negative feedback excitation signal is generated according to the output signal of the linear displacement sensor, and the negative feedback excitation signal acts on an excitation signal of an excitation coil of the linear displacement sensor.

[0027] The method of the present application can acquire the output signal of the linear displacement sensor and then demodulate the output signal of the linear displacement sensor, so as to generate a negative feedback excitation signal according to the output signal of the linear displacement sensor, and the negative feedback excitation signal acts on the excitation coil of the linear displacement sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a structural schematic diagram of a demodulation device of a linear displacement sensor disclosed in an embodiment of the present application;

[0030] Figure 2 is a circuit diagram of an adder disclosed in an embodiment of the present application;

[0031] Figure 3 is a circuit diagram of a signal generator disclosed in an embodiment of the present application;

[0032] Figure 4 It is a schematic diagram of a circuit of a signal generator power supply disclosed in an embodiment of the present application;

[0033] Figure 5 It is a schematic diagram of a full-wave rectifier filter circuit disclosed in an embodiment of the present application;

[0034] Figure 6 This is a circuit diagram of a subtractor disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0036] The demodulation device of the linear displacement sensor of the embodiment of the present application includes a demodulation module and a negative feedback excitation module; the demodulation module is connected to the negative feedback excitation module, the demodulation module is used to demodulate the output signal of the linear displacement sensor and output the signal demodulation result, the negative feedback excitation module is used to generate a negative feedback excitation signal based on the output signal of the linear displacement sensor, and the negative feedback excitation signal acts on the excitation signal of the excitation coil that controls the linear displacement sensor.

[0037] In an embodiment of the present application, the demodulation device of the linear displacement sensor includes a demodulation module for realizing a demodulation function, and further includes a negative feedback excitation module. Thus, while realizing the demodulation function, the negative feedback excitation signal generated by the negative feedback excitation module can also act on the excitation signal of the excitation coil controlling the linear displacement sensor, thereby realizing negative feedback adjustment of the linear displacement sensor, wherein the negative feedback adjustment can improve the linearity of the linear displacement sensor, overcome the problem of poor linearity caused by the manufacturing process of the linear displacement sensor, and thereby improve the accuracy of the linear displacement sensor.

[0038] Specifically, the original linear displacement sensor is affected by the manufacturing process and will introduce manufacturing errors at both ends of the test range, resulting in large linearity errors. The original probe test of the same LVDT probe, the linearity test when the excitation signal is not introduced into the feedback and the excitation signal is introduced into the feedback is shown in the figure below. The maximum linear error of the original linear displacement sensor is -0.67% at the maximum distance point of 11mm in the positive stroke, the maximum linear error is -0.46% at the maximum distance point of 11mm in the positive stroke when there is circuit demodulation without feedback, and the maximum linear error is -0.29% at the maximum distance point of 11mm in the positive stroke after the excitation signal introduces negative feedback. The linearity of LVDT products can be greatly improved by introducing negative feedback through the measured excitation signal.

[0039] In an embodiment of the present application, the linear displacement sensor can be a linear variable differential transformer displacement sensor, i.e., an LVDT sensor, wherein the LVDT is composed of a primary coil, two secondary coils, and a movable iron core. When an AC excitation voltage is applied to the primary coil, a voltage is induced in the secondary coil. Since the movement of the iron core changes the distribution of the magnetic field, the induced voltage in the secondary coil is affected. When the primary coil senses the change in the position of the iron core, an alternating voltage is provided to generate an induced electromotive force in the secondary coil, and because the induced electromotive force is different due to the different positions of the iron core, the displacement of the iron core provides a voltage output signal, and this output signal is linearly related to the displacement of the iron core.

[0040] In an embodiment of the present application, the linear displacement sensor can be a rotary variable differential transformer angular displacement sensor, that is, an RVDT sensor. The RVDT consists of a hollow cylinder and an armature core that can rotate freely in the hollow cylinder. The primary coil is wound around the hollow cylinder and input with alternating current of constant amplitude. Two secondary coils with equal number of turns are wound on both sides of the primary coil, at equal distances from the primary coil and in a differential configuration, and the two secondary coils are connected in series. When an alternating current passes through the primary winding, an alternating magnetic field is generated around the core, and the magnetic field extends radially outward from the primary winding. When the core rotates, the magnetic lines of force pass through the secondary winding, inducing a changing voltage in the secondary winding. The voltage induced in each secondary winding depends on the rotation angle of the core, and the output voltage of the RVDT sensor is positive with the angular displacement of the core.

[0041] In the embodiments of the present application, regarding the demodulation process of the linear displacement sensor, please refer to the prior art.

[0042] In an optional embodiment, the demodulation device is an analog circuit.

[0043] This optional implementation can use analog circuits to design a demodulation device, so that the demodulation device based on analog circuit design can overcome the problems of high analog-to-digital conversion processing delay, complexity and low reliability compared to the demodulation device designed with analog-to-digital conversion circuits, and thus has a higher response speed and the advantages of simplicity and high reliability.

[0044] In an alternative implementation, see Figure 1 , Figure 1 Schematic diagram of a demodulation device for a linear displacement sensor disclosed in an embodiment of the present application. Figure 1 As shown, the negative feedback excitation module includes an adder and a signal generator, wherein the input end of the adder is used to be connected to the signal demodulated by the secondary coil of the linear displacement sensor, the signal generator is electrically connected to the output end of the adder, the adder is used to perform signal addition operation on the output signal of the linear displacement sensor, and the signal generator is used to generate a negative feedback excitation signal according to the addition operation result of the adder.

[0045] This optional implementation can perform signal addition operation on the output signals of the linear displacement sensor through an adder, and then generate a negative feedback excitation signal according to the addition operation result of the adder.

[0046] For this optional implementation,

[0047] For the above optional implementation, the circuit of the adder is as follows: Figure 2 As shown, Figure 2 1 is a circuit diagram of an adder disclosed in an embodiment of the present application. For the working principle of the adder circuit, please refer to the prior art.

[0048] For the above optional implementation, the circuit of the signal generator is as follows: Figure 3 As shown, Figure 3 1 is a circuit diagram of a signal generator disclosed in an embodiment of the present application. For the working principle of the circuit of the signal generator, please refer to the prior art.

[0049] In an optional implementation, the negative feedback excitation signal generated by the signal generator is a square wave signal.

[0050] This optional implementation can use a square wave signal as a negative feedback excitation signal, wherein the square wave signal has the advantages of simple circuit implementation and strong anti-interference ability.

[0051] It should be noted that the signal generator circuit is implemented using square waves, which does not limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0052] In an optional implementation, the negative feedback excitation module further includes a signal generator power supply, wherein the signal generator power supply is electrically connected to the signal generator for providing power to the signal generator.

[0053] This optional implementation may provide power to the signal generator via a signal generator power supply.

[0054] For the above optional implementation, the circuit of the signal generator power supply is as follows: Figure 4 As shown, Figure 4 1 is a schematic diagram of a circuit of a signal generator power supply disclosed in an embodiment of the present application. For the working principle of the circuit of the signal generator power supply, please refer to the prior art.

[0055] In an optional embodiment, the negative feedback excitation module also includes a power supply step-down circuit, wherein the output end of the power supply step-down circuit is electrically connected to the power supply of the signal generator, and the input end of the power supply step-down circuit is connected to a 12V DC power supply for converting the 12V voltage into the operating voltage of the signal generator.

[0056] In an optional embodiment, the demodulation module includes a full-wave rectifier filter circuit and a subtractor, wherein the subtractor is electrically connected to the full-wave rectifier filter circuit, the full-wave rectifier filter circuit is used to perform shaping and filtering on the output signal of the linear displacement sensor, and the subtractor is used to perform subtraction operation on the shaped and filtered signal to obtain a demodulation result.

[0057] This optional implementation can perform shaping and filtering on the output signal of the linear displacement sensor through a full-wave rectification and filtering circuit.

[0058] For the above optional implementation, the full-wave rectifier filter circuit is as follows: Figure 5 As shown, Figure 5 1 is a schematic diagram of a full-wave rectifier filter circuit disclosed in an embodiment of the present application. For the working principle of the full-wave rectifier filter circuit, please refer to the prior art.

[0059] For the above optional implementation, the circuit of the subtractor is as follows: Figure 6 As shown, Figure 6 1 is a circuit diagram of a subtractor disclosed in an embodiment of the present application. For the working principle of the subtractor circuit, please refer to the prior art.

[0060] In an optional implementation, the demodulation module further includes an output driver, the output driver is electrically connected to the subtractor, and the output driver is used to reduce the output impedance.

[0061] This optional implementation can reduce the output impedance of the demodulation device through output driving.

[0062] In an optional implementation, the demodulation module and the negative feedback excitation module are on the same double-sided SMD circuit board.

[0063] This optional implementation can integrate the demodulation module and the negative feedback excitation module on the same double-sided SMD circuit board, wherein the double-sided SMD circuit board has the advantages of high integration and high welding quality reliability.

[0064] In a second aspect, the present invention provides a demodulation method for a linear displacement sensor, the method being applied to a demodulation device as in any one of the aforementioned embodiments, the method comprising:

[0065] Obtaining the output signal of the linear displacement sensor;

[0066] Demodulating the output signal of the linear displacement sensor;

[0067] A negative feedback excitation signal is generated according to the output signal of the linear displacement sensor, and the negative feedback excitation signal acts on an excitation signal of an excitation coil controlling the linear displacement sensor.

[0068] The method of the present application can acquire the output signal of the linear displacement sensor and then demodulate the output signal of the linear displacement sensor, so as to generate a negative feedback excitation signal according to the output signal of the linear displacement sensor, and the negative feedback excitation signal acts on the excitation signal of the excitation coil that controls the linear displacement sensor.

[0069] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.

[0070] In addition, the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0071] Furthermore, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0072] It should be noted that if the function is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can essentially be embodied in the form of a software product, or in other words, the part that contributes to the prior art or the part of the technical solution. The computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM) random access memory (RAM), disk or optical disk, and other media that can store program codes.

[0073] In this document, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0074] The above are only embodiments of the present application and are not intended to limit the scope of protection of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. A demodulation device for a linear displacement sensor, characterized in that: The demodulation device comprises a demodulation module and a negative feedback excitation module; The demodulation module is connected to the negative feedback excitation module, the demodulation module is used to demodulate the output signal of the linear displacement sensor and output the signal demodulation result, the negative feedback excitation module is used to generate a negative feedback excitation signal based on the output signal of the linear displacement sensor, and the negative feedback excitation signal acts on the excitation signal of the excitation coil that controls the linear displacement sensor.

2. The demodulation device according to claim 1, characterized in that The demodulation device is an analog circuit.

3. The demodulation device according to claim 1, characterized in that: The negative feedback excitation module includes an adder and a signal generator, wherein the input end of the adder is used to be connected to the signal demodulated by the secondary coil of the linear displacement sensor, the signal generator is electrically connected to the output end of the adder, the adder is used to perform signal addition operation on the output signal of the linear displacement sensor, and the signal generator is used to generate the negative feedback excitation signal according to the addition operation result of the adder.

4. The demodulation device according to claim 3, characterized in that: The negative feedback excitation signal generated by the signal generator is a square wave signal.

5. The demodulation device according to claim 3, characterized in that: The negative feedback excitation module further includes a signal generator power supply, wherein the signal generator power supply is electrically connected to the signal generator for providing power to the signal generator.

6. The demodulation device according to claim 5, characterized in that The negative feedback excitation module also includes a power supply step-down circuit, wherein the output end of the power supply step-down circuit is electrically connected to the power supply of the signal generator, and the input end of the power supply step-down circuit is connected to a 12V DC power supply, for converting the 12V voltage into the working voltage of the power supply of the signal generator.

7. The demodulation device according to claim 5, characterized in that: The demodulation module includes a full-wave rectifier filter circuit and a subtractor, wherein the subtractor is electrically connected to the full-wave rectifier filter circuit, the full-wave rectifier filter circuit is used to perform shaping and filtering on the output signal of the linear displacement sensor, and the subtractor is used to perform subtraction operation on the shaped and filtered signal to obtain the demodulation result.

8. The demodulation device according to claim 7, characterized in that: The demodulation module further includes an output driver, the output driver is electrically connected to the subtractor, and the output driver is used to reduce output impedance.

9. The demodulation device according to claim 7, characterized in that: The demodulation module and the negative feedback excitation module are on the same double-sided SMD circuit board.

10. A demodulation method for a linear displacement sensor, characterized in that: The method is applied to the demodulation device according to any one of claims 1 to 9, and the method comprises: Obtaining the output signal of the linear displacement sensor; Demodulating the output signal of the linear displacement sensor; A negative feedback excitation signal is generated according to the output signal of the linear displacement sensor, and the negative feedback excitation signal acts on an excitation signal of an excitation coil of the linear displacement sensor.

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