Rod displacement sensor tester

Abstract

The utility model relates to the technical field of device detection, in particular to a rod displacement sensor tester, which comprises a main control module, a man-machine interaction module, a modulation and demodulation module, an analog-digital (AD) acquisition module and a test interface, the output end of the main control module is connected with the excitation module control end of the modulation-demodulation module, the output end of the signal conditioning module of the modulation-demodulation module is connected with the AD acquisition module and then is connected with the input end of the main control module, the man-machine interaction module is in communication connection with the main control module, and the test interface is connected with the modulation-demodulation module. The modulation and demodulation module is connected with the to-be-tested rod displacement sensor through a test cable, the excitation module of the modulation and demodulation module is connected with the primary coil side of the to-be-tested rod displacement sensor, and the signal conditioning module of the modulation and demodulation module is connected with the secondary coil side of the rod displacement sensor.

Description

Technical Field

[0001] This utility model relates to the field of device testing technology, specifically to a rod displacement sensor tester. Background Technology

[0002] As an important component in fly-by-wire flight control systems, stick displacement sensors need to undergo complete device testing before leaving the factory. The current traditional methods of stick displacement sensor testing basically require manual operation through multiple testing procedures and corresponding equipment to detect each item to be tested. The traditional method has low testing efficiency and is prone to false triggers. Utility Model Content

[0003] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a rod displacement sensor tester.

[0004] To achieve the above objectives, this utility model provides the following technical solution: a rod displacement sensor tester, comprising a main control module, a human-machine interaction module, a modulation and demodulation module, an AD acquisition module, and a test interface. The modulation and demodulation module includes an excitation module and a signal conditioning module. The output terminal of the main control module is connected to the control terminal of the excitation module of the modulation and demodulation module. The output terminal of the signal conditioning module of the modulation and demodulation module is connected to the AD acquisition module and then connected to the input terminal of the main control module. The human-machine interaction module is communicatively connected to the main control module. The test interface is connected to the modulation and demodulation module and is connected to the rod displacement sensor to be tested via a test cable. The excitation module of the modulation and demodulation module is connected to the primary coil side of the rod displacement sensor to be tested, and the signal conditioning module of the modulation and demodulation module is connected to the secondary coil side of the rod displacement sensor.

[0005] In some embodiments, the test apparatus further includes a temperature control module, a temperature sensor, a cooling fan, and a relay. The temperature sensor is located near the main control module, and its signal terminal is connected to the main control module. One end of the relay is connected to the cooling fan, and the other end is connected to the power supply. The control terminal of the relay is connected to the main control module.

[0006] In some embodiments, the modulation and demodulation module is an AD698 LVDT signal conditioner.

[0007] In some embodiments, the main control module is a ruggedized computer.

[0008] In some embodiments, the human-computer interaction module is a touch display.

[0009] Compared with existing technologies, the beneficial effects of this invention are: this tester can be used for position signal detection and voltage polarity detection of the stick displacement sensor in a fly-by-wire flight control system. It features zero-position detection and adjustment, polarity detection, and limit position adjustment functions for a four-redundant stick displacement sensor, and displays the four-channel voltage values ​​of the stick displacement sensor, thus improving detection efficiency and accuracy.

[0010] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. The embodiments of this application will provide a detailed description and understanding of the application. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the module connection principle of this utility model;

[0012] Figure 2 This is a connection diagram of the modulation and demodulation module;

[0013] Figure 3 This is the LVDT signal conditioning circuit in the embodiment;

[0014] Figure 4 Here is the block diagram of AD698;

[0015] Figure 5 This is a diagram showing the relationship between the output voltage ripple and the filter in the embodiment.

[0016] In the diagram: 1. Main control module; 2. Human-computer interaction module; 3. Modulation and demodulation module; 4. AD acquisition module; 5. Test interface;

[0017] 31. Excitation module; 32. Signal conditioning module. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0019] Please see Figure 1This utility model provides a technical solution: a rod displacement sensor tester, including a main control module, a human-machine interaction module, a modulation and demodulation module, an AD acquisition module, and a test interface. The modulation and demodulation module includes an excitation module and a signal conditioning module. The output terminal of the main control module is connected to the control terminal of the excitation module of the modulation and demodulation module. The output terminal of the signal conditioning module of the modulation and demodulation module is connected to the AD acquisition module and then connected to the input terminal of the main control module. The human-machine interaction module is communicatively connected to the main control module. The test interface is connected to the modulation and demodulation module and is connected to the rod displacement sensor to be tested through a test cable. The excitation module of the modulation and demodulation module is connected to the primary coil side of the rod displacement sensor to be tested, and the signal conditioning module of the modulation and demodulation module is connected to the secondary coil side of the rod displacement sensor.

[0020] As an inductive sensor, the rod displacement sensor requires an excitation signal for its primary coil to generate an alternating magnetic field for the secondary coil to pick up. Under otherwise constant conditions, the signal output by the secondary coil is related to the position of the iron core at its center, and the signal contains interference signals, which need to be conditioned to remove them.

[0021] Figure 2 The primary coil, magnetic core, and secondary coil form a rod displacement LVDT sensor, along with a modulation / demodulation module (divided into an excitation module and a signal conditioning module), a main control module, and a power supply processing module. After receiving the user's sensor measurement command from the FPGA main control module, the excitation drive module generates a set sinusoidal excitation signal to drive the sensor's primary coil. The signal conditioning module of the demodulation module adjusts the secondary coil voltage to DC voltage, which is then acquired, decoded, and uploaded to the main control module for display.

[0022] In practical applications, the modulation and demodulation module is an AD698 LVDT signal conditioner.

[0023] The modulation and demodulation module uses the AD698 LVDT signal conditioner, which includes a sine wave oscillator and a power amplifier to generate the excitation signal driving the primary-side LVDT, while its output has short-circuit protection. The AD698 can also convert the secondary-side output to a DC voltage. The AD8615 rail-to-rail amplifier buffers the AD698 output and drives a low-power 18-bit successive approximation analog-to-digital converter (ADC). The AD698 can be considered a complete LVDT signal conditioning subsystem. It can convert the mechanical position of the LVDT sensor into a unipolar DC voltage with high accuracy and repeatability. All circuit functions are integrated on-chip. By adding a few external passive components to set the frequency and gain, the AD698 can convert the raw LVDT secondary-side output into a proportional DC signal. The AD698 has a built-in low-distortion sine wave oscillator to drive the LVDT primary side. The sine wave frequency is determined by a single capacitor, with a frequency range of 20Hz to 20kHz and an amplitude range of 2V RMS to 24V RMS. In this embodiment, the excitation signal output is configured to be 7V@1800Hz, and its signal conditioning principle is as follows: Figure 3 As shown.

[0024] The LVDT secondary output consists of two sine waves used to directly drive the AD698. The AD698 decodes the LVDT by synchronously demodulating the amplitude modulation input (secondary, A) and a fixed input reference voltage (primary-secondary summation or fixed input, B). A common problem with previous solutions was that any drift in the driving oscillator amplitude directly caused gain errors in the output. The AD698 calculates the ratio of the LVDT output to its input excitation, canceling out any drift effects and thus eliminating these errors.

[0025] See the block diagram of AD698. Figure 4 The input consists of two independent synchronous demodulation channels. Channel B monitors the drive excitation of the LVDT. C2 filters the full-wave rectified output and then sends it to the operational circuit. Channel A performs identically except for the externally provided comparator pin. Since Channel A may reach 0V output when the LVDT is empty, the primary voltage (Channel B) is typically used to trigger the demodulator in Channel A. Additionally, a phase compensation network may be needed to add phase lead or lag to Channel A to compensate for the phase shift from the primary to the secondary side of the LVDT. For a half-bridge circuit, phase shift is not critical, and the Channel A voltage is sufficient to trigger the demodulator. All Channel A channels have independent LVDT measurement capabilities, with a measurement range of ±15V. Combined with 16-bit AD acquisition, its effective resolution is 0.15mV.

[0026] After demodulation and filtering of both channels, a voltage divider circuit equipped with a duty cycle multiplier is used to calculate the A / B ratio. The output of the voltage divider is the duty cycle. If A / B equals 1, the duty cycle is 100%. (This signal can be used if pulse width modulation output is required). The duty cycle drive circuit modulates and filters a reference current proportional to the duty cycle. The output amplifier adjusts the 500μA reference current and converts it into a voltage. The output transfer function is: V OUT =I REF × B A ×R2, where I REF =500uA.

[0027] This solution follows the dual-supply operation (±15V) design procedure in the AD698 datasheet, setting the excitation frequency to 1800Hz, the system bandwidth to 250Hz, and the output voltage to 7V.

[0028] The AD698's internal oscillator typically generates a small amount of ripple that propagates to the output. This solution uses a passive low-pass filter to reduce this ripple to the required level. Some trade-offs are necessary when selecting the capacitor value to set the system bandwidth. Choosing a smaller capacitor value will give the system a higher bandwidth but will increase the output voltage ripple. This ripple can be suppressed by increasing the parallel capacitance across the feedback resistor (used to set the output voltage level), but doing so will increase phase hysteresis.

[0029] The AD8615 operational amplifier buffers the output of the AD698, which ensures the AD7992 ADC is driven with a low-impedance source (high-impedance sources significantly degrade the AC performance of the ADC). A low-pass filter is positioned between the output of the AD698 and the input of the AD8615, serving two main purposes: 1) limiting the input current of the AD8615; and 2) filtering output voltage ripple. The AD8615's internal protection circuitry allows the input to withstand input voltages higher than the supply voltage. This is important because the AD698's output voltage can swing ±11V from a ±15V supply. Higher voltages can be applied to the input as long as the input current is limited to 5mA. This is primarily because the AD8615 (1pA) has extremely low input bias current, allowing for the use of larger resistors. Using these resistors increases thermal noise, leading to increased overall output voltage noise. The AD8615 is an ideal amplifier for buffering and driving the 12-bit SARADCAD7992 input because it features input overvoltage protection and rail-to-rail swing capability at both the input and output.

[0030] For LVDT signal conditioning circuits, the main source of output noise is the output ripple of the AD698. In comparison, other noise sources (resistive noise of the AD8615, input voltage noise, and output voltage noise) are much smaller. When the capacitor value is 0.39μF and the parallel capacitor across the feedback resistor is 10nF (e.g....), the noise is significantly reduced. Figure 5 When (as shown), the output voltage ripple of AD698 is 0.4mVrms.

[0031] The total output dynamic range of the system can be calculated as follows: divide the full-scale output signal (5V) by the total output root mean square noise (0.4mV rms), and then convert it to dB. The result is approximately 84.86dB.

[0032] Dynamic range = 20 × log(7V / 0.4mV) = 84.86dB.

[0033] The main control module is a ruggedized computer, and the human-computer interaction module is a touch screen display.

[0034] All test equipment is equipped with a power adapter, which converts 220V AC power to 12V DC power. The power adapter has an internal voltage regulation circuit with overvoltage and undervoltage protection functions. The inrush current to the mains power grid during operation is <10A / 220VAC.

[0035] The test apparatus also includes a temperature control module, a temperature sensor, a cooling fan, and a relay. The temperature sensor is located near the main control module, and its signal terminal is connected to the main control module. One end of the relay is connected to the cooling fan, and the other end is connected to the power supply. The control terminal of the relay is connected to the main control module.

[0036] The temperature control system's 12V power supply provides power to the entire module. Relays include those controlling the 12V power connection and those controlling the fan. The temperature control system collects internal temperature information from the host unit; if the temperature exceeds 35°C, the fan will activate to improve the internal microenvironment. Temperature measurement and cooling devices are installed near temperature-sensitive modules to ensure timely temperature adjustments.

[0037] The system uses a host and resource cards with good low-temperature performance (-20℃~50℃), capable of normal operation at -20℃. Therefore, no heating module is designed inside the host. To quickly dissipate heat when the host temperature is too high, two cooling fans are designed on the left and right sides of the host. The left side is the air intake, and the right side is the air exhaust. When the host temperature is too high, the cooling fans will automatically start to cool down. The fans are powered by 12VDC and have a speed of 4500rpm.

[0038] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A rod displacement sensor testing apparatus, characterized in that: The system includes a main control module, a human-machine interface module, a modulation and demodulation module, an AD acquisition module, and a test interface. The modulation and demodulation module includes an excitation module and a signal conditioning module. The output of the main control module is connected to the control terminal of the excitation module of the modulation and demodulation module. The output of the signal conditioning module of the modulation and demodulation module is connected to the AD acquisition module and then to the input of the main control module. The human-machine interface module is communicatively connected to the main control module. The test interface is connected to the modulation and demodulation module and is connected to the rod displacement sensor under test through a test cable. The excitation module of the modulation and demodulation module is connected to the primary coil side of the rod displacement sensor under test, and the signal conditioning module of the modulation and demodulation module is connected to the secondary coil side of the rod displacement sensor.

2. The rod displacement sensor tester according to claim 1, characterized in that: The test apparatus also includes a temperature control module, a temperature sensor, a cooling fan, and a relay. The temperature sensor is located near the main control module, and its signal terminal is connected to the main control module. One end of the relay is connected to the cooling fan, and the other end is connected to the power supply. The control terminal of the relay is connected to the main control module.

3. The rod displacement sensor tester according to claim 1, characterized in that: The modulation and demodulation module is an AD698 LVDT signal conditioner.

4. The rod displacement sensor tester according to claim 1, characterized in that: The main control module is a ruggedized computer.

5. The rod displacement sensor tester according to claim 1, characterized in that: The human-computer interaction module is a touch display.

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