Non-contact torque motor displacement measurement system and method

Abstract

The application discloses a non-contact torque motor displacement measurement system and method, and relates to the field of torque motor displacement measurement.The measurement system comprises a torque motor, a high / low temperature test box, a semi-physical simulation platform, an amplifier and a driver.The test method is to establish the relationship among the armature displacement, induced electromotive force and driving signal through the current coefficient and displacement coefficient, and indirectly solve the displacement.The identification steps of the current coefficient and displacement coefficient include: establishing the mathematical relationship among the induced electromotive force, armature displacement and driving signal;setting two groups of experiments, collecting experimental data;data processing and function fitting of signals;identifying the current coefficient and displacement coefficient;and verifying the accuracy of parameters.The non-contact torque motor displacement measurement system and method have the advantages of simplicity, low cost, suitability for application scenes such as vibration, high temperature and low temperature, and on-line measurement with the system.

Description

Technical Field

[0001] This invention relates to the field of torque motor displacement measurement technology, and in particular to a non-contact torque motor displacement measurement system and method. Background Technology

[0002] Electro-hydraulic servo valves are tiny, precision control components in electro-hydraulic servo control systems. They are widely used in aircraft flight control surfaces, nose wheel steering, electronic anti-skid brakes, radar servo systems, door retraction and extension, air intake adjustment, missile servo mechanisms, engine main fuel metering, main combustion pump servo mechanisms, guide vane and compressor angles, afterburner metering, tail nozzles, and vector nozzles.

[0003] In dual-nozzle baffle servo valves or jet deflector servo valves, the torque motor is the electromechanical conversion device of the servo valve. It converts weak coil electrical signals into the deflection motion of the armature, driving the baffle or deflector to move, outputting a differential pressure difference in the pre-stage, and driving the next stage spool valve to move. The motion state of the armature is directly related to the pre-stage pressure difference, so it is necessary to detect the motion state of the armature. Currently, the commonly used detection method is to use a laser displacement sensor combined with an armature extension device to detect the displacement of the armature. However, since current laser displacement sensors cannot withstand high temperatures, this method is only suitable for static detection in the laboratory. Laser sensors cannot detect under high and low temperature test environments. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a non-contact torque motor displacement measurement system and method, which can non-contactly measure the displacement of the armature online under environments such as high and low temperatures. The system is easy to operate and provides good measurement results.

[0005] The technical solution adopted in this invention is as follows:

[0006] This invention discloses a non-contact torque motor displacement measurement system and method. The measurement system includes: a torque motor, a high / low temperature test chamber, a hardware-in-the-loop simulation platform, an amplifier, and a driver.

[0007] The torque motor includes an induction coil, an upper magnetic conductor, an armature, a lower magnetic conductor, an excitation coil, and a magnet. The magnet is mounted on the lower magnetic conductor, the upper magnetic conductor is mounted above the magnet, and the armature is mounted between the upper and lower magnetic conductors, forming a complete magnetic circuit.

[0008] Furthermore, the amplifier has an adjustable amplification factor and a filtering function. The amplification factor is adjusted according to the signal magnitude output by the induction coil to adapt to the acquisition limitations of the hardware-in-the-loop simulation platform.

[0009] Furthermore, the driver can amplify the weak control signal into a voltage drive signal or current drive signal with a certain power.

[0010] Furthermore, the torque motor is placed in a high / low temperature test chamber. The hardware-in-the-loop simulation platform outputs an alternating control signal, which is then driven by a driver to output a drive signal to the excitation coil. Under the action of the excitation magnetic field generated by the excitation coil, the armature makes a corresponding deflection motion, outputting displacement, thereby cutting the magnetic field lines and generating an induced electromotive force signal in the induction coil. This signal is amplified by a set factor by an amplifier and acquired by the hardware-in-the-loop simulation platform. The accurately calibrated current coefficient k is then used to generate the signal. i Displacement coefficient k x Substituting into the following formula, and combining the induced electromotive force signal and the driving signal, the displacement x(t) of the armature is calculated; e(t) is the induced electromotive force, k i K is the current coefficient. x Let i(t) be the displacement coefficient, and i(t) be the control current.

[0011]

[0012] Furthermore, the current coefficient k i and the displacement coefficient k x The calibration and identification steps are as follows:

[0013] Step 1: Establish the mathematical relationship between the induced electromotive force, armature displacement, and driving signal;

[0014] The derivation process is as follows: In the study of the magnetic circuit characteristics of the servo valve torque motor, the magnetic circuit of the torque motor is generally simplified and analyzed in conjunction with Kirchhoff's laws, as shown in the following equation:

[0015] φ1R1+φ3R3=2M0+N c i(t)

[0016] φ2R2+φ4R4=2M0-N c i(t)

[0017] φ1R1+φ4R4=M0

[0018] φ1+φ2-φ3-φ4=0

[0019] φ1=φ3, φ2=φ4

[0020] In the formula: R i For the magnetic reluctance at the air gap (i = 1, 2, 3, 4), Φ i is the magnetic flux (i = 1, 2, 3, 4); M0 is the polarization magnetomotive force of a single permanent magnet; N c t represents the number of coil turns; i(t) represents the control current.

[0021] Solving for Φ1 and Φ2, we get:

[0022]

[0023]

[0024]

[0025]

[0026] In the formula, the magnetic flux generated by the control current i(t) is Φ. c R g Φ g Let t be the magnetic reluctance and magnetic flux of each of the four air gaps in the middle of the armature, x(t) be the displacement of the armature, and g be the initial air gap height.

[0027] Because x(t) << g, the magnetic flux Φ through the armature a It can be represented as:

[0028]

[0029] The induced electromotive force e(t) can be expressed as:

[0030]

[0031] In the formula, k i K is the current coefficient. x This is the displacement coefficient.

[0032] Step 2: Set up two sets of experiments and collect experimental data;

[0033] Both sets of experimental data include: obtaining the driving signal-time data relationship curve i A (t), i B (t); Displacement signal-time data relationship curve x A (t), x B (t), the relationship curve between induced electromotive force signal and time data e A (t), e B (t) Three types;

[0034] The displacement signal-time data relationship curve is acquired by a laser displacement sensor. An extended measuring point is installed at the left end of the armature. The deflection motion of the armature is converted into the deflection motion of the extended measuring point. The laser emitted by the laser displacement sensor is directly projected onto the extended measuring point.

[0035] Step 3: Data processing and signal function fitting;

[0036] Based on the experimental data from step 2, the driving signal-time data relationship curves i are fitted using functions respectively. A (t), i B (t) and the curve of the relationship between displacement signal and time data xA (t), x B (t), and substitute it into the formula for calculating the induced electromotive force e(t) in step 1 to obtain the relationship curves e of the induced electromotive force signal-time data for two sets. A (t) and e B (t) is shown below:

[0037]

[0038]

[0039] Step 4: Identify the current coefficient k i Displacement coefficient k x ;

[0040] Based on the formula for calculating the induced electromotive force e(t) in step 1, a mathematical model of the induced electromotive force is established in Simulink. Using the experimentally measured induced electromotive force under the corresponding operating conditions, the current coefficient k is identified based on the least squares method. i Displacement coefficient k x .

[0041] Step 5: Verify parameter accuracy;

[0042] The verification process is as follows: the current coefficient k identified in step 4 is... i Displacement coefficient k x Substituting the expression for the induced electromotive force e(t) from step 1, experiments were conducted under two sets of driving signals, C and D, respectively. The corresponding driving signal-time data relationship curves were collected and fitted. C (t), i D (t) and the relationship curve between displacement signal and time data x C (t), x D Substituting (t) into the expression for the induced electromotive force e(t) in step 1, we can calculate the induced electromotive force-time data relationship curve e. C (t), e D (t), and the curve e showing the relationship between the induced electromotive force and time data collected in the experiment. CS (t), e DS (t) is used to compare and verify the accuracy of the model parameters.

[0043] Furthermore, according to the formula for calculating the induced electromotive force e(t) in step 1, under the triangular wave drive signal, when the displacement undergoes a sudden nonlinear change, its derivative dx(t) / dt will suddenly increase, and the induced electromotive force will also suddenly increase. When the armature is limited, the displacement does not change with time, and its derivative dx(t) / dt is 0. Therefore, the induced electromotive force will decrease to a very small value and remain unchanged. Based on the above rules, the armature can be limited or stuck according to the change law of the induced electromotive force, and fault diagnosis can be performed.

[0044] Compared with existing armature displacement measurement methods, this invention has the following advantages:

[0045] (1) The testing system is simple and low in cost;

[0046] (2) Applicable to applications involving vibration, high temperature, and low temperature;

[0047] (3) The product does not need to be disassembled after installation and can be measured online with the system;

[0048] (4) The armature movement fault can be diagnosed based on the change law of induced electromotive force under triangular wave signal. Attached Figure Description

[0049] Figure 1 Schematic diagram of multi-condition non-contact displacement measurement principle;

[0050] Figure 2 Torque motors simplify magnetic circuits;

[0051] Figure 3 These are experimental data under the A-driving signal;

[0052] Figure 4 Experimental data under the B-driving signal;

[0053] Figure 5 The principle of measuring armature displacement using a laser displacement sensor;

[0054] Figure 6 Comparison of calculated and experimental induced electromotive force under C-driven signal;

[0055] Figure 7 Comparison of calculated and experimental induced electromotive force under D-driving signal;

[0056] Figure 8 These are experimental data under a triangular wave signal. Detailed Implementation

[0057] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solutions of the present invention, and it should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0058] like Figure 1 As shown, the present invention discloses a non-contact torque motor displacement measurement system and method, including a torque motor 1, a high / low temperature test chamber 2, a hardware-in-the-loop simulation platform 3, an amplifier 4, and a driver 5;

[0059] The torque motor 1 includes an induction coil 1.1, an upper magnetic conductor 1.2, an armature 1.3, a lower magnetic conductor 1.4, an excitation coil 1.5, and a magnet 1.6. The magnet 1.6 is mounted on the lower magnetic conductor 1.4, the upper magnetic conductor 1.2 is mounted above the magnet 1.6, and the armature 1.3 is mounted between the upper magnetic conductor 1.2 and the lower magnetic conductor 1.4, forming a complete magnetic circuit.

[0060] The torque motor 1 is placed in the high / low temperature test chamber 2. The hardware-in-the-loop simulation platform 3 outputs an alternating control signal, which is then driven by the driver 5 to the excitation coil 1.5. Under the action of the excitation magnetic field generated by the excitation coil 1.5, the armature 1.3 makes a corresponding deflection motion, outputting displacement, thereby cutting the magnetic field lines and generating an induced electromotive force signal in the induction coil 1.1. This signal is amplified by the amplifier 4 by a set factor and acquired by the hardware-in-the-loop simulation platform 3. The accurately calibrated current coefficient k is then... i Displacement coefficient k x Substituting the values ​​into the following equation, and combining the induced electromotive force signal and the driving signal, the displacement x(t) of the armature can be calculated.

[0061]

[0062] The current coefficient k i and the displacement coefficient k x The calibration and identification steps are as follows:

[0063] Step 1: Establish the mathematical relationship between the induced electromotive force, armature displacement, and driving signal;

[0064] In the study of the magnetic circuit characteristics of servo valve torque motors, the following methods are generally used: Figure 2 The simplified magnetic circuit shown is analyzed using Kirchhoff's laws, as shown in the following equation:

[0065] φ1R1+φ3R3=2M0+N c i(t)

[0066] φ2R2+φ4R4=2M0-N c i(t)

[0067] φ1R1+φ4R4=M0

[0068] φ1+φ2-φ3-φ4=0

[0069] φ1=φ3, φ2=φ4

[0070] In the formula: R i Φ is the magnetic reluctance at the air gap. i is the magnetic flux (i = 1, 2, 3, 4); M0 is the polarization magnetomotive force of a single permanent magnet; N c t represents the number of coil turns; i(t) represents the control current.

[0071] Solving for Φ1 and Φ2, we get:

[0072]

[0073]

[0074]

[0075]

[0076] In the formula, the magnetic flux generated by the control current i(t) is Φ. c R g Φ g Let t be the magnetic reluctance and magnetic flux of each of the four air gaps in the middle of the armature, x(t) be the displacement of the armature, and g be the initial air gap height.

[0077] Because x(t) << g, the magnetic flux Φ through the armature a It can be represented as:

[0078]

[0079] The induced electromotive force e(t) can be expressed as:

[0080]

[0081] In the formula, k i K is the current coefficient. x This is the displacement coefficient.

[0082] Step 2: Set up two sets of experiments and collect feedback signals;

[0083] like Figure 3 The data shown is the experimental data under the A driving signal. Figure 4 These are experimental data under the B-driven signal, including the driving signal-time data relationship curve i(t), the displacement signal-time data relationship curve x(t), and the induced electromotive force signal-time data relationship curve e(t).

[0084] The displacement signal-time data x(t) is acquired by the laser displacement sensor 7, such as... Figure 5As shown, an extended measuring point 6 is installed at the left end of the armature 1.3. The deflection motion of the armature 1.3 is converted into the deflection motion of the extended measuring point 6. The laser emitted by the laser displacement sensor 7 is directly projected onto the extended measuring point 6.

[0085] Step 3: Data processing and signal function fitting;

[0086] Based on the experimental data from step 2, the driving signal-time data relationship curves i are fitted using functions respectively. A (t), i B (t) and the relationship curve between displacement signal and time data x A (t), x B (t), and by substituting into the formula for calculating the induced electromotive force e(t), two sets of induced electromotive force-time data relationship curves are obtained. A (t) and e B (t) is shown below:

[0087]

[0088]

[0089] Step 4: Identify the current coefficient k i Displacement coefficient k x ;

[0090] Two mathematical models of induced electromotive force (EMF) were established in Simulink. Using the experimentally measured induced EMF under corresponding operating conditions, the current coefficient k was identified based on the least squares method. i Displacement coefficient k x .

[0091] Step 5: Verify the accuracy of parameters.

[0092] The current coefficient k identified in step 4 i Displacement coefficient k x Substituting the expression for the induced electromotive force e(t) from step 1, experiments were conducted under C and D driving signals, and the corresponding driving signal-time data i were collected and fitted. C (t), i D (t) and displacement signal-time data x C (t), x D Substituting (t) into the expression for the induced electromotive force e(t) in step 1, we can calculate the induced electromotive force e. C (t), e D (t), the same as the e collected in the experiment CS (t), e DS (t) is compared, and the effect is as follows: Figure 6 , Figure 7As shown, the accuracy of the identification model parameters is verified.

[0093] like Figure 8 The data shown is experimental data under a triangular wave signal. The displacement-time curve shows that the armature was limited when it reached its limit position, and the gain changed before the limit was reached. The induced electromotive force (EMF)-time curve shows a sharp rise corresponding to the change in displacement gain, and a flattened section after the fall corresponding to the armature's limitation. Analysis can be performed using the induced EMF e(t) calculation formula from step 1. When the displacement changes abruptly, its derivative increases suddenly, and the induced EMF also increases suddenly. When the armature is limited, the displacement does not change with time, and its derivative is 0. At this time, only the mutual inductance of the coil exists, so the induced EMF decreases and remains constant. Based on the above patterns, the motion state of the armature can be determined under a triangular wave drive signal based on the change in induced EMF, indicating whether limitation or jamming has occurred, thus enabling fault diagnosis.

[0094] Compared with existing armature displacement measurement methods, this invention has the following advantages:

[0095] (1) The testing system is simple and low in cost;

[0096] (2) Applicable to applications involving vibration, high temperature, and low temperature;

[0097] (3) The product does not need to be disassembled after installation and can be measured online with the system;

[0098] (4) The armature movement fault can be diagnosed based on the change law of induced electromotive force under triangular wave signal.

[0099] The present invention has been described in detail above with reference to the accompanying drawings and specific embodiments. It should be noted that some (but not all) of the disclosed examples are shown in the drawings. In fact, many different examples can be described, and these examples should not be construed as limited to those set forth herein. Rather, these examples are described to further highlight the positive effects of the present invention, and all aspects not detailed herein are considered to be well-known or conventional techniques in the art.

Claims

1. A non-contact torque motor displacement measurement method, using a non-contact torque motor displacement measurement system, the system comprising a torque motor (1), a high / low temperature test chamber (2), a hardware-in-the-loop simulation platform (3), an amplifier (4), and a driver (5); The torque motor (1) includes an induction coil (1.1), an upper magnetic conductor (1.2), an armature (1.3), a lower magnetic conductor (1.4), an excitation coil (1.5), and a magnet (1.6). The magnet (1.6) is mounted on the lower magnetic conductor (1.4), the upper magnetic conductor (1.2) is mounted above the magnet (1.6), and the armature (1.3) is mounted between the upper magnetic conductor (1.2) and the lower magnetic conductor (1.4), forming a complete magnetic circuit. Its features are, The torque motor (1) is placed in the high / low temperature test chamber (2). The alternating control signal output by the hardware-in-the-loop simulation platform (3) is sent to the excitation coil (1.5) via the driver (5). Under the action of the excitation magnetic field generated by the excitation coil (1.5), the armature (1.3) makes a corresponding deflection motion and outputs displacement, thereby cutting the magnetic field lines and generating an induced electromotive force signal in the induction coil (1.1). The signal is amplified by the amplifier (4) by a set factor and collected by the hardware-in-the-loop simulation platform (3). The calibrated current coefficient k is then used to generate the signal. i Displacement coefficient k x Substituting into equation (1), and combining the induced electromotive force signal e(t) and the driving signal i(t), the displacement x(t) of the armature (1.3) is calculated; ---Equation (1); The current coefficient k i and the displacement coefficient k x The calibration and identification steps are as follows: Step 1: Establish the mathematical relationship between the induced electromotive force, armature displacement, and driving signal; The induced electromotive force e(t) is expressed as: ； In the formula, k i K is the current coefficient. x N is the displacement coefficient. c R represents the number of coil turns; i(t) represents the drive signal-time data. g Φ g Let Φ be the magnetic reluctance and magnetic flux of each of the four air gaps in the armature center position, x(t) be the displacement of the armature, and g be the initial air gap height; a The magnetic flux of the armature; Step 2: Set up two sets of experiments and collect experimental data; Both sets of experimental data include three types: driving signal-time data i(t), displacement signal-time data x(t), and induced electromotive force signal-time data e(t). The displacement signal-time data x(t) is acquired by a laser displacement sensor (7). An extended measuring point (6) is installed on the left end of the armature (1.3). The deflection motion of the armature (1.3) is converted into the deflection motion of the extended measuring point (6). The laser emitted by the laser displacement sensor (7) is directly projected onto the extended measuring point (6). Step 3: Data processing and signal function fitting; Based on the experimental data from step 2, the driving signal-time data i are fitted using functions respectively. A (t), i B (t) and displacement signal-time data x A (t), x B (t), and substitute it into the formula for calculating the induced electromotive force e(t) in step 1 to obtain two sets of induced electromotive forces e A (t) and e B (t) is shown below: ； Step 4: Identify the current coefficient k i Displacement coefficient k x ; Based on the formula for calculating the induced electromotive force e(t) in step 1, the induced electromotive force e is established in Simulink. A (t) and e B The mathematical model of (t) is used, and the induced electromotive force under the corresponding working condition measured experimentally is used to identify the current coefficient k based on the least squares method. i Displacement coefficient k x ; Step 5: Verify the accuracy of parameters.

2. The non-contact torque motor displacement measurement method according to claim 1, characterized in that, The derivation of the induced electromotive force e(t) is as follows: The magnetic circuit of the torque motor is simplified and analyzed in conjunction with Kirchhoff's laws, as shown in the following equation: ； In the formula: R i Φ is the magnetic reluctance at the air gap. i is the magnetic flux, where i = 1, 2, 3, 4; M0 is the polarization magnetomotive force of a single permanent magnet; N c t represents the number of coil turns; i(t) represents the driving signal. Solving for Φ1 and Φ2, we get: ， ， ， ， In the formula, the magnetic flux generated by the driving signal i(t) is Φ. c R g Φ g Let x(t) be the magnetic reluctance and magnetic flux of each of the four air gaps in the middle of the armature, g be the displacement of the armature, and g be the initial air gap height. Because x(t) << g, the magnetic flux Φ through the armature a Represented as: ； The induced electromotive force e(t) is expressed as: ； In the formula, k i K is the current coefficient. x This is the displacement coefficient.

3. The non-contact torque motor displacement measurement method according to claim 1, characterized in that, The parameter accuracy verification process involves verifying the current coefficient k obtained in step 4. i Displacement coefficient k x Substituting the expression for the induced electromotive force e(t) from step 1, experiments were conducted under two sets of driving signals, C and D, respectively. The corresponding driving signal-time data i were collected and fitted. C (t), i D (t) and displacement signal-time data x C (t), x D Substituting (t) into the expression for the induced electromotive force e(t) in step 1, we can calculate the induced electromotive force e. C (t), e D (t), the same as the e collected in the experiment CS (t), e DS (t) is used to compare and verify the accuracy of the model parameters.

4. The non-contact torque motor displacement measurement method according to claim 1, characterized in that, It also includes armature fault diagnosis. According to the calculation formula of induced electromotive force e(t) in step 1, when the displacement changes abruptly under the triangular wave drive signal, its derivative dx(t) / dt will suddenly increase, and the induced electromotive force will also suddenly increase. The armature will be limited. When the displacement does not change with time, its derivative dx(t) / dt is 0, and the induced electromotive force will decrease to a very small value and remain unchanged. Based on the above rules and the change law of induced electromotive force, it is determined whether the armature is limited or stuck, and fault diagnosis is performed.

5. The non-contact torque motor displacement measurement method according to claim 1, characterized in that, The amplifier (4) has an adjustable amplification factor and a filtering function. The amplification factor is adjusted according to the signal output of the induction coil (1.1) to adapt to the acquisition limitations of the hardware-in-the-loop simulation platform (3).

6. The non-contact torque motor displacement measurement method according to claim 1, characterized in that, The driver (5) has multi-mode output, which amplifies the weak control signal into a voltage drive signal or current drive signal with a certain power.

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