Aircraft strength test control signal conversion device

Abstract

The application provides an airplane strength test control signal conversion device, which comprises a power module, an EtherCAT coupler module and a digital-analog conversion module; the EtherCAT coupler module is used for receiving an EtherCAT protocol digital signal from a PC / PLC controller through an Ethernet input end of the EtherCAT coupler module, processing the EtherCAT protocol, distributing power, and forwarding the digital signal to the digital-analog conversion module through an E-Bus bus; and the digital-analog conversion module is used for receiving the digital signal through the E-Bus bus, converting the digital signal into a ±10V analog voltage signal, and outputting the analog voltage signal to an external actuator through an analog output end of the digital-analog conversion module. The sensor analog signal is converted into a digital signal for long-distance transmission, and the digital signal is restored into an analog signal before a control end, so that the problem that an analog signal is susceptible to electromagnetic interference in a long-distance transmission process is solved.

Description

Technical Field

[0001] This invention relates to the field of control signal conversion technology, and more specifically to a control signal conversion device for aircraft strength testing. Background Technology

[0002] In aircraft strength testing, sensors and control equipment typically use analog signals to achieve automated control. Analog signals transmit information in the form of continuously changing voltage or current, and their transmission process is easily affected by various factors such as environmental noise and electromagnetic interference, leading to signal quality degradation, distortion, or drift. Especially in long-distance transmission scenarios, signal attenuation and interference accumulation are particularly prominent, severely impacting data accuracy and system control precision.

[0003] Currently, a common solution to the problem of analog signals being susceptible to electromagnetic interference during transmission is to use shielded cables. Shielded cables typically wrap a layer of metallic shielding material, such as aluminum foil or braided metal mesh, around their conductors. This outer shielding layer forms electromagnetic isolation, effectively blocking external electromagnetic interference (EMI) and radio frequency interference (RFI) from entering the signal line. The advantage of this method is its strong anti-interference capability, which can suppress common-mode noise and external radiated interference to a certain extent. However, its disadvantages are also significant, including higher cable cost, increased weight, and the need for proper grounding during installation; improper grounding will greatly reduce the shielding effect.

[0004] For high-precision testing scenarios, such as position control accuracy requiring 0.1mm in servo tests, shielded cables alone are insufficient to completely eliminate errors caused by interference. Electromagnetic interference can cause signal jitter or deviation, thus affecting the positioning accuracy of the actuator. Therefore, under such stringent conditions, traditional shielded cable methods are no longer adequate to meet the requirements for signal integrity and control accuracy. More advanced technologies, such as digital signal transmission, signal conditioning, or fiber optic communication, are needed to improve anti-interference performance and system reliability. Summary of the Invention

[0005] In view of this, the embodiments of this specification provide an aircraft strength test control signal conversion device to improve the quality of long-distance analog signals.

[0006] The embodiments in this specification provide the following technical solutions:

[0007] An aircraft strength test control signal conversion device, comprising: Power supply module, EtherCAT coupler module, and digital-to-analog converter module; The DC output terminal of the power module is connected to the power input terminal of the EtherCAT coupler module and the power input terminal of the digital-to-analog converter module, respectively. The Ethernet input of the EtherCAT coupler module is connected to an external PC / PLC controller, and the E-Bus interface of the EtherCAT coupler module is connected to the E-Bus interface of the digital-to-analog converter module. The analog output of the digital-to-analog converter module is connected to an external actuator; The power module is used to convert external AC power to DC power and provide operating power for the EtherCAT coupler module and the digital-to-analog converter module; The EtherCAT coupler module is used to receive EtherCAT protocol digital signals from the PC / PLC controller through the Ethernet input terminal of the EtherCAT coupler module, process the EtherCAT protocol and distribute power, and forward the digital signals to the digital-to-analog converter module through the E-Bus bus. The digital-to-analog converter module is used to receive digital signals via the E-Bus bus, convert the digital signals into ±10V analog voltage signals, and output them to external actuators through the analog output terminal of the digital-to-analog converter module.

[0008] Furthermore, the EtherCAT coupler module includes: Ethernet input interface, Ethernet output interface, Ethernet physical layer chip, EtherCAT slave controller, configuration storage unit, E-Bus interface driver circuit, E-Bus connector, power supply circuit, power output terminal and indicator light circuit; The Ethernet input interface is connected to the receive channel of the Ethernet physical layer chip, the Ethernet output interface is connected to the transmit channel of the Ethernet physical layer chip, and the Ethernet physical layer chip is connected to the EtherCAT slave controller through the independent interface MII. The configuration storage unit is connected to the configuration pin of the EtherCAT slave controller, and the data bus of the EtherCAT slave controller is connected to the input terminal of the E-Bus interface driver circuit. The output of the E-Bus interface driver circuit is connected to the data pin of the E-Bus connector. The power supply circuit includes a filter / protection circuit and a DC-DC converter. The input of the filter / protection circuit is connected to an external 24V DC power supply, and the output of the filter / protection circuit is connected to the input of the DC-DC converter. The output of the DC-DC converter is connected to the power supply pins of the Ethernet physical layer chip, the EtherCAT slave controller, and the E-Bus interface driver circuit, respectively. The power output terminal is connected in parallel with the input terminal of the filter / protection circuit to provide a 24V external power supply to the digital-to-analog converter module. The indicator light circuit is connected to the status output pin of the EtherCAT slave controller and the power monitoring pin of the E-Bus interface driver circuit, respectively. The Ethernet input interface is used to receive digital signals, and the Ethernet output interface is used to cascade the next slave device. Ethernet physical layer chips are used to transmit and receive 100BASE-TX physical layer signals; The EtherCAT slave controller is used to process EtherCAT protocol frames and extract or insert process data; The configuration storage unit is used to store the operating parameters and configuration information of the storage module; The E-Bus interface driver circuit is used to convert the 3.3V data signal output from the EtherCAT slave controller into a 5V E-Bus bus level. The E-Bus connector is used to provide data signals, clock signals, and 5V logic power to the digital-to-analog converter module via a data line; The power supply circuit is used to convert the external 24V power supply to 5V logic power supply and to power the various circuits inside the module. The power output terminal is used to provide 24V power to the digital-to-analog converter module for peripheral devices; The indicator light circuit is used to display the module's power status, operating status, error status, E-Bus status, and network link status.

[0009] Furthermore, the power supply circuit includes: Fuse F1, TVS diode D1, common mode inductor L1, electrolytic capacitor C1, reverse polarity protection diode D2, filter capacitor C2, and ferrite bead FB1; The input terminal of fuse F1 is connected to the +24V power supply. The output terminal of fuse F1 is connected to one end of TVS diode D1 and the first input terminal of common mode inductor L1, respectively. The other end of TVS diode D1 is connected to power ground GND. The first output terminal of the common mode inductor L1 is connected to the positive terminal of the electrolytic capacitor C1. The second output terminal of the common mode inductor L1 is connected to the input terminal of the external voltage regulator chip via the ferrite bead FB1. The negative terminal of the electrolytic capacitor C1 is connected to the power ground GND. The anode of the reverse polarity protection diode D2 is connected to the positive terminal of the electrolytic capacitor C1, and its cathode is connected to the positive terminal of the filter capacitor C2 and the input terminal of the voltage regulator chip. The negative terminal of the filter capacitor C2 is connected to the power ground GND. Fuse F1 is used to blow and protect downstream circuits when an overcurrent fault occurs in the circuit. TVS diode D1 is used to suppress transient overvoltage surges on the power line; The common-mode inductor L1 is used to suppress common-mode electromagnetic interference on the power line; Electrolytic capacitor C1 is used for primary filtering and energy storage of the input power supply; The reverse polarity protection diode D2 is used to prevent damage to subsequent circuits when the power supply polarity is reversed. Filter capacitor C2 is used for secondary high-frequency filtering of the power supply; The FB1 ferrite bead is used to provide input power.

[0010] Furthermore, the DC-DC converter includes: Start-up resistor R, PWM controller, MOSFET Q1, transformer T1, and rectifier diode D3; One end of the start-up resistor R is connected to the +24V_IN power supply, the other end of the start-up resistor R is connected to the start-up pin of the PWM controller, the drive output pin of the PWM controller is connected to the gate of MOSFET Q1, the drain of MOSFET Q1 is connected to the same-name terminal of the primary winding of transformer T1, and the source of MOSFET Q1 is connected to the primary ground GND_PRI. The opposite-named terminal of the primary winding of transformer T1 is connected to the +24V_IN power supply, and the same-named terminal of the secondary winding of transformer T1 is connected to the anode of rectifier diode D3. An isolation barrier is provided between the primary side and the secondary side of transformer T1 to achieve electrical isolation between the primary ground GND_PRI and the secondary grounds GND_SEC and GND_ISO; The startup resistor R is used to provide the initial operating current for the PWM controller during startup; The PWM controller is used to generate PWM drive signals and control the switching state of MOSFET Q1; MOSFET Q1 is used to turn on and off at high frequency according to the PWM drive signal, generating alternating current on the primary side of transformer T1; Transformer T1 is used to realize voltage transformation, energy transmission and primary-secondary electrical isolation; The rectifier diode D3 is used to rectify the high-frequency AC voltage output from the secondary side of the transformer.

[0011] Furthermore, the DC-DC converter also includes: Filtering network and feedback optocoupler; The output of the filter network is connected to +5V_OUT, and the input of the filter network is connected to the cathode of rectifier diode D3. The input of the feedback optocoupler is connected to the output of the filter network, and the output of the feedback optocoupler is connected to the feedback pin of the PWM controller. The filter network is used to smooth the pulsating DC voltage after rectification and output a stable +5V_OUT DC voltage. Feedback optocouplers are used to isolate and feed back the output voltage sampling signal to the PWM controller, thereby achieving closed-loop voltage regulation control.

[0012] Furthermore, the E-Bus interface driver circuit includes: Level shifting / buffering chip and E-Bus connector; One side of the level conversion / buffer chip is connected to the 3.3V data line of the EtherCAT slave controller, and the other side of the level conversion / buffer chip is connected to the data pin of the E-Bus connector. The power supply pin of the level conversion / buffer chip is connected to the 5V_E-BUS power supply, and the ground pin of the level conversion / buffer chip is connected to the digital ground GND. The first pin of the E-Bus connector is connected to the 5V E-BUS power supply, the second pin is connected to the digital ground GND, the third pin is connected to the DATA0 signal line, the fourth pin is connected to the DATA1 signal line, the fifth pin is connected to the CLK clock line, the sixth pin is connected to the SELECT select line, the seventh pin is connected to the +24V OUT external power supply, and the eighth pin is connected to the GND 24V external power supply ground. The level conversion / buffer chip is used to convert the 3.3V data signal level output from the EtherCAT slave controller to the 5V E-Bus bus level and to buffer and drive the signal; The E-Bus connector is used to provide 5V logic power, data signals DATA0 and DATA1, clock signal CLK, chip select signal SELECT, 24V peripheral power and corresponding power ground to the digital-to-analog converter module through the various pins of the E-Bus connector.

[0013] Furthermore, the digital-to-analog conversion module includes: Communication controller / FPGA, digital isolator, isolated DC-DC power supply, multiple digital-to-analog converters (DACs), multiple output amplification and protection circuits, output terminal blocks, external power input interface and diagnostic feedback circuit; The input of the communication controller / FPGA is connected to the E-Bus input interface, and the output of the communication controller / FPGA is connected to the primary side of the digital isolator via a parallel port or a high-speed SPI bus. The secondary side of the digital isolator is connected to the digital inputs of multiple digital-to-analog converters (DACs) via an isolated SPI bus. The analog output of each digital-to-analog converter (DAC) is connected to the input of a corresponding output amplification and protection circuit. The output terminals of multiple output amplification and protection circuits are respectively connected to the corresponding pins of the output terminal block; The input terminal of the isolated DC-DC power supply is connected to the +5V_IN power supply, and the output terminal of the isolated DC-DC power supply is connected to the digital-to-analog converter (DAC) and the output amplification and protection circuit, respectively. The communication controller / FPGA is used to parse the E-Bus protocol, perform data buffering and allocation, and implement DC clock synchronization management; Digital isolators are used to achieve electrical isolation between the communication side and the analog side, ensuring the safety of signal transmission; An isolated DC-DC power supply is used to convert the input +5V power supply into ±15V and +5V analog power supplies that are electrically isolated from the communication side, providing independent power for the digital-to-analog conversion and output circuits; Digital-to-analog converters (DACs) are used to convert received digital signals into high-precision analog voltage signals; The output amplification and protection circuit is used to amplify, filter, and protect the analog voltage output by the DAC. The output terminal block is used to output the converted analog voltage signal to external test control equipment.

[0014] Furthermore, the digital-to-analog conversion module also includes: External power input interface and diagnostic feedback circuit; The external power input interface is connected to +24V and GND; The input terminals of the diagnostic feedback circuit are connected to the current detection points of the output amplification and protection circuits, respectively, and the output terminal of the diagnostic feedback circuit is connected to the fault feedback pin of the communication controller / FPGA through optocoupler isolation. The external power input interface is used to receive an external 24V power supply to power the output stage circuit. The diagnostic feedback circuit is used to monitor the output current of each channel in real time, and feeds back to the communication controller / FPGA through optocoupler isolation when an overcurrent or short circuit fault occurs.

[0015] Furthermore, the digital-to-analog converter (DAC) includes: DAC chip, low-pass filter network, and operational amplifier; The digital input of the DAC chip is connected to the isolated SPI bus, the REF+ pin of the DAC chip is connected to the precision reference voltage source, the REF- pin of the DAC chip is connected to the analog ground, and the VOUT pin of the DAC chip is connected to the input of the low-pass filter network. The low-pass filter network includes a first resistor R1 and a first capacitor C1. One end of the first resistor R1 is connected to the VOUT pin of the DAC chip, and the other end of the first resistor R1 is connected to one end of the first capacitor C1 and the non-inverting input of the operational amplifier. The other end of the first capacitor C1 is connected to analog ground. The inverting input of the operational amplifier is connected to the output of the operational amplifier via a feedback resistor, and the positive and negative power supply pins of the operational amplifier are connected to +15V_ISO and -15V_ISO, respectively. DAC chips are used to convert isolated digital signals from SPI bus inputs into high-precision analog voltage signals; Low-pass filter networks are used to filter out high-frequency noise components in the DAC output signal; The operational amplifier is used to amplify the filtered analog voltage in phase, adjusting the voltage range to the ±10V standard output.

[0016] Furthermore, the digital-to-analog converter module also includes output protection and current detection amplifier circuits; The output terminal of the operational amplifier is connected to the input terminal of the output protection and current detection amplifier circuit, which is used to limit the current, clamp the overvoltage, and detect and protect the output signal. The output protection and current detection amplifier circuit includes an output protection circuit, a current detection amplifier circuit, an overcurrent detection branch, and a fault feedback branch connected in sequence. The output protection circuit is used to limit the current and clamp the overvoltage of the output signal. The current sensing amplifier circuit is used to sample and amplify the output current; The overcurrent detection branch is used to compare the amplified current signal with a preset threshold to determine whether an overcurrent or short circuit fault has occurred. The fault feedback branch is used to send the fault flag as the result of the fault feedback to the communication controller / FPGA.

[0017] Compared with the prior art, the beneficial effects that at least one technical solution adopted in the embodiments of this specification can achieve include at least: By converting analog signals from sensors into digital signals for long-distance transmission and then converting the digital signals back into analog signals at the control end, the problem of analog signals being susceptible to electromagnetic interference during long-distance transmission is fundamentally solved. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is an overall schematic diagram of the aircraft strength test control signal conversion device according to an embodiment of the present invention; Figure 2This is a schematic diagram of the EtherCAT coupler module of the aircraft strength test control signal conversion device according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the power supply circuit of the aircraft strength test control signal conversion device according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the DC-DC converter of the aircraft strength test control signal conversion device according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the E-Bus interface drive circuit of the aircraft strength test control signal conversion device according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the analog-to-digital conversion module of the aircraft strength test control signal conversion device according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the digital-to-analog converter (DAC) of the aircraft strength test control signal conversion device according to an embodiment of the present invention. Detailed Implementation

[0020] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] like Figure 1 As shown, this embodiment provides an aircraft strength test control signal conversion device, including a power supply module, an EtherCAT coupler module, and a digital-to-analog converter module.

[0023] The power supply module uses a switching power supply. Its AC input terminal is connected to an external 220V AC power supply, and its DC output terminal outputs 24V DC power. The 24V DC output terminal of the power supply module is electrically connected to the power input terminal (24V+, GND) of the EtherCAT coupler module and the external power input interface (+24V, GND) of the digital-to-analog converter module, respectively, to provide operating power to both modules.

[0024] The Ethernet input (EtherCAT IN) of the EtherCAT coupler module is connected to an external PC / PLC controller via a network cable to receive EtherCAT protocol digital signals. The E-Bus interface of the EtherCAT coupler module is electrically connected to the E-Bus interface of the digital-to-analog converter module via the backplane bus to realize data communication and power transmission.

[0025] The analog output of the digital-to-analog converter module is connected to an external actuator (such as a servo valve or driver of an electric linear actuator) via a shielded cable, outputting a ±10V analog voltage control signal to it.

[0026] like Figure 2 As shown, the EtherCAT coupler module includes an Ethernet input interface, an Ethernet output interface, an Ethernet physical layer chip, an EtherCAT slave controller, a configuration storage unit (EEPROM), an E-Bus interface driver circuit, an E-Bus connector, a power supply circuit, a power output terminal, and an indicator light circuit.

[0027] The Ethernet input interface (RJ45) connects to the receive channel of the Ethernet physical layer chip (PHY), and the Ethernet output interface (RJ45) connects to the transmit channel of the Ethernet physical layer chip. The Ethernet physical layer chip connects to the corresponding pins of the EtherCAT slave controller through the Media Independent Interface (MII) to realize the transmission and reception of EtherCAT protocol frames.

[0028] The configuration memory unit (EEPROM) is connected to the configuration pins of the EtherCAT slave controller via the I²C bus, and is used to store the MAC address, device name, and operating parameters of the module. The 16-bit data bus of the EtherCAT slave controller is connected to the input of the E-Bus interface driver circuit.

[0029] The power supply circuit includes a filter / protection circuit and a DC-DC converter. The input of the filter / protection circuit is connected to an external 24V DC power supply, and its output is connected to the input of the DC-DC converter. The output of the DC-DC converter is connected to the power supply pins of the Ethernet physical layer chip, the EtherCAT slave controller, and the E-Bus interface driver circuit, respectively, providing a 5V logic power supply.

[0030] The power output terminal is connected in parallel with the input of the filter / protection circuit to provide a 24V external power supply to the digital-to-analog converter module. The indicator light circuit is connected to the status output pin of the EtherCAT slave controller and the power monitoring pin of the E-Bus interface driver circuit, respectively, and displays the module's power status, operating status, error status, E-Bus status, and network link status via LED indicators on the panel.

[0031] like Figure 3 As shown, the specific connection relationship of the power supply circuit is as follows: the input terminal of fuse F1 is connected to the +24V power supply, and the output terminal of fuse F1 is connected to one end of TVS diode D1 and the first input terminal of common mode inductor L1. The other end of TVS diode D1 is connected to power ground GND.

[0032] The first output terminal of common-mode inductor L1 is connected to the positive terminal of electrolytic capacitor C1, and the second output terminal of common-mode inductor L1 is connected to an external voltage regulator chip (input terminal of a DC-DC converter) via ferrite bead FB1. The negative terminal of electrolytic capacitor C1 is connected to power ground GND.

[0033] The anode of the reverse polarity protection diode D2 is connected to the positive terminal of the electrolytic capacitor C1, and its cathode is connected to the positive terminal of the filter capacitor C2 and the input terminal of the voltage regulator chip. The negative terminal of the filter capacitor C2 is connected to the power ground GND.

[0034] Fuse F1 is used to blow and protect downstream circuits when an overcurrent fault occurs in the circuit; TVS diode D1 is used to suppress transient overvoltage surges on the power line; common-mode inductor L1 is used to suppress common-mode electromagnetic interference on the power line; electrolytic capacitor C1 is used for primary filtering and energy storage of the input power supply; reverse polarity protection diode D2 is used to prevent damage to downstream circuits when the power supply polarity is reversed; filter capacitor C2 is used for secondary high-frequency filtering of the power supply; ferrite bead FB1 is used to provide input power that suppresses high-frequency noise.

[0035] like Figure 4 As shown, the DC-DC converter includes a start-up resistor R, a PWM controller, a MOSFET Q1, a transformer T1, a rectifier diode D3, a filter network, and a feedback optocoupler.

[0036] One end of the startup resistor R is connected to the +24V_IN power supply, and the other end is connected to the startup pin of the PWM controller to provide the initial operating current for the PWM controller during startup. The drive output pin of the PWM controller is connected to the gate of MOSFET Q1 to generate a PWM drive signal to control the switching state of Q1.

[0037] The drain of MOSFET Q1 is connected to the primary winding terminal of transformer T1, and the source is connected to primary ground GND_PRI. The non-primary winding terminal of transformer T1 is connected to the +24V_IN power supply. MOSFET Q1 turns on and off at high frequency according to the PWM drive signal, generating alternating current on the primary winding of transformer T1.

[0038] The secondary winding terminal of transformer T1 is connected to the anode of rectifier diode D3. An isolation barrier is provided between the primary and secondary sides of transformer T1 to achieve electrical isolation between primary ground GND_PRI and secondary grounds GND_SEC and GND_ISO. Rectifier diode D3 is used to rectify the high-frequency AC voltage output from the secondary side of the transformer.

[0039] The input of the filter network is connected to the cathode of rectifier diode D3, and the output is connected to +5V_OUT. This network smooths and filters the pulsating DC voltage after rectification, outputting a stable +5V_OUT DC voltage. The input of the feedback optocoupler is connected to the output of the filter network, and the output is connected to the feedback pin of the PWM controller. This isolates and feeds back the output voltage sampling signal to the PWM controller, achieving closed-loop voltage regulation control.

[0040] like Figure 5 As shown, the E-Bus interface driver circuit includes a level conversion / buffer chip and an E-Bus connector.

[0041] One side of the level shifter / buffer chip (side A) is connected to the 3.3V data line of the EtherCAT slave controller, and the other side (side B) is connected to the data pin of the E-Bus connector. The power supply pin of the level shifter / buffer chip is connected to the 5V E-BUS power supply, and the ground pin is connected to digital ground (GND).

[0042] The first pin of the E-Bus connector is connected to the 5V E-BUS power supply, the second pin is connected to the digital ground (GND), the third pin is connected to the DATA0 signal line, the fourth pin is connected to the DATA1 signal line, the fifth pin is connected to the CLK clock line, the sixth pin is connected to the SELECT select line, the seventh pin is connected to the +24V OUT external power supply, and the eighth pin is connected to the GND 24V external power supply ground.

[0043] The level conversion / buffer chip is used to convert the 3.3V data signal level output from the EtherCAT slave controller to the 5V E-Bus bus level and buffer the signal drive. The E-Bus connector is used to provide the digital-to-analog converter module with 5V logic power, data signals DATA0 and DATA1, clock signal CLK, chip select signal SELECT, as well as 24V peripheral power and corresponding power ground through its various pins.

[0044] like Figure 6 As shown, the digital-to-analog converter module includes a communication controller / FPGA, a digital isolator, an isolated DC-DC power supply, multiple 16-bit digital-to-analog converters (DACs), multiple output amplification and protection circuits, an output terminal block, an external power input interface, and a diagnostic feedback circuit.

[0045] The input of the communication controller / FPGA is connected to the E-Bus input interface to receive E-Bus bus signals from the EtherCAT coupler module. The output of the communication controller / FPGA is connected to the primary side of the digital isolator via a parallel port or high-speed SPI bus to parse the E-Bus protocol, perform data buffering and distribution, and implement DC clock synchronization management.

[0046] The secondary side of the digital isolator is connected to the digital inputs of four digital-to-analog converters (DACs) via an isolated SPI bus to achieve electrical isolation between the communication side and the analog side, ensuring the security of signal transmission. The analog output of each DAC is connected to the input of a corresponding output amplification and protection circuit.

[0047] The output terminals of the four output amplification and protection circuits are respectively connected to the corresponding pins of the output terminal block (OUT1+, OUT1-, OUT2+, OUT2-, OUT3+, OUT3-, OUT4+, OUT4-) to output the converted analog voltage signal to the external test control equipment.

[0048] The input of the isolated DC-DC power supply is connected to the +5V_IN power supply (E-Bus interface), and the output generates ±15V_ISO and +5V_ISO isolated power supplies respectively. These are connected to the power supply pins of the digital-to-analog converter (DAC) and the output amplification and protection circuit, and are used to convert the input +5V power supply into ±15V and +5V analog power supplies that are electrically isolated from the communication side, so as to provide independent power supply for the digital-to-analog converter and the output circuit.

[0049] The external power input interface is connected to +24V and GND to receive an external 24V power supply to power the output stage circuit. The input terminals of the diagnostic feedback circuit are connected to the current detection points of the output amplification and protection circuits, respectively. The output terminal is connected to the fault feedback pin of the communication controller / FPGA through optocoupler isolation. This is used to monitor the output current of each channel in real time and to provide feedback to the communication controller / FPGA through optocoupler isolation in the event of an overcurrent or short-circuit fault.

[0050] like Figure 7 As shown, each channel's digital-to-analog converter (DAC) includes a DAC chip, a low-pass filter network, an operational amplifier, an output protection and current detection amplifier circuit, and a fault flag output terminal.

[0051] The digital input of the DAC chip is connected to the isolated SPI bus, the REF+ pin is connected to a precision reference voltage source, the REF- pin is connected to analog ground, and the VOUT pin is connected to the input of a low-pass filter network, which is used to convert the digital signal input from the isolated SPI bus into a high-precision analog voltage signal.

[0052] The low-pass filter network includes a first resistor R1 (100Ω) and a first capacitor C1 (100pF). One end of the first resistor R1 is connected to the VOUT pin of the DAC chip, and the other end is connected to one end of the first capacitor C1 and the non-inverting input of the operational amplifier. The other end of the first capacitor C1 is connected to analog ground, which is used to filter out high-frequency noise components in the DAC output signal.

[0053] The inverting input of the operational amplifier is connected to its output via a feedback resistor, forming a non-inverting amplifier circuit with a gain of 4. The positive and negative power supply pins of the operational amplifier are connected to +15V_ISO and -15V_ISO, respectively, to amplify the filtered analog voltage in a non-inverting manner, adjusting the voltage range to the ±10V standard output.

[0054] The output protection and current detection amplifier circuit includes an output protection circuit, a current detection amplifier, an overcurrent detection branch, and a fault feedback branch connected in sequence.

[0055] The output protection circuit is used to limit the current and clamp the overvoltage of the output signal. Current sensing amplifiers are used to sample and amplify the output current; The overcurrent detection branch is used to compare the amplified current signal with a preset threshold to determine whether an overcurrent or short circuit fault has occurred. The fault feedback branch is used to send the fault flag as the result of the fault feedback to the communication controller / FPGA.

[0056] During aircraft strength testing, analog signals (such as displacement and force signals) from field sensors are acquired by a nearby PLC and converted into digital signals. These digital signals are then transmitted over a network cable for tens to hundreds of meters before entering the communication interface of this device (i.e., the Ethernet input of the EtherCAT coupler module).

[0057] The EtherCAT coupler module processes EtherCAT protocol frames through its Ethernet physical layer chip and EtherCAT slave controller, extracts process data, and converts the data into 5V E-Bus bus signals through the E-Bus interface driver circuit. These signals, along with 5V logic power and 24V external power, are then transmitted to the digital-to-analog converter module via the E-Bus connector.

[0058] The communication controller / FPGA of the digital-to-analog converter module parses the E-Bus protocol and distributes digital signals to four 16-bit DAC chips via an isolated SPI bus. Each DAC chip converts the digital signal into an analog voltage, which is then low-pass filtered and amplified by an operational amplifier to a range of ±10V before being output through the output terminal block.

[0059] The output ±10V analog voltage signal is connected to the adjacent main control system of the test via a very short shielded cable, driving the actuator to complete high-precision loading. Throughout the process, the exposure distance of the analog signal is controlled within an extremely short range, while long-distance transmission is accomplished by a digital signal with strong anti-interference capabilities, thus achieving a balance between high precision and high reliability.

[0060] Beneficial effects of the embodiments of the present invention: This invention fundamentally solves the problem of electromagnetic interference affecting analog signals during long-distance transmission by converting analog signals from sensors into digital signals locally for long-distance transmission and then converting the digital signals back into analog signals at the control end. In practical applications, this device achieved a repeatability accuracy of less than 0.1 mm in aircraft strength servo loading tests, fully meeting the requirements of high-precision testing.

[0061] The EtherCAT industrial Ethernet protocol is used for digital signal transmission, fully utilizing the strong anti-interference capability of digital signals. Simultaneously, the digital-to-analog converter module incorporates a digital isolator and an isolated DC-DC power supply to achieve electrical isolation between the communication and analog sides, effectively blocking the propagation paths of ground loop interference and common-mode noise. Multi-stage filtering protection measures in the power supply circuit, including the common-mode inductor L1, ferrite bead FB1, and TVS diode D1, further enhance the device's operational stability in complex electromagnetic environments.

[0062] For long-distance transmission, ordinary network cables (twisted pair) are used instead of traditional dedicated analog shielded cables, significantly reducing cable costs. For transmission distances of hundreds of meters, the cost of network cables is only about one-tenth that of shielded cables of the same length. Furthermore, network cable connectors are highly standardized, making installation convenient and maintenance simple.

[0063] This device can be directly connected to existing analog sensors and analog control equipment without any modification or replacement of the front-end sensors or back-end controllers. For existing test systems, simply add a PLC for analog-to-digital conversion on the sensor side and install this device on the control cabinet side to upgrade the system, thus maximizing the protection of existing equipment investment.

[0064] The power supply circuit employs multiple protections, including fuse F1, reverse connection protection diode D2, and TVS diode D1, to prevent damage to the module from overcurrent, reverse connection, and transient overvoltage. The digital-to-analog converter channel features an output amplification and protection circuit composed of current sensing resistor R3, a comparator, and a TVS diode. This circuit monitors the output current in real time and provides fast protection by feeding back the feedback to the communication controller / FPGA in case of overcurrent or short circuit. The DC-DC converter uses a feedback optocoupler to achieve closed-loop voltage regulation control, ensuring a stable and reliable output voltage.

[0065] The device combines standard industrial modules with self-designed circuits, using standard components (such as the LM500xPWM controller, DAC8811 digital-to-analog converter, OPA4197 precision operational amplifier, ADuM digital isolator, etc.), which are widely available and easy to maintain. Each functional module is independently packaged, allowing for accurate fault location and quick replacement.

[0066] The device is integrated into a standard U2.5 chassis (483mm × 111mm × 300mm), which can be easily installed in a 19-inch standard test control cabinet. The front panel of the chassis is equipped with handles on both sides for easy handling and plugging / unplugging. The communication interface uses the FCAT6-RJ45 standard interface, and the analog output uses an aviation connector. The interface definitions are clear, and field wiring is simple.

[0067] This device is not only suitable for servo loading systems in aircraft strength testing, but can also be widely applied to various industrial automation control scenarios that require long-distance transmission of high-precision analog signals, such as servo motor control, hydraulic servo systems, and precision positioning platforms, and has broad prospects for promotion and application.

[0068] In summary, this invention solves the problem of anti-interference in long-distance transmission of analog signals in aircraft strength testing with low cost, standardized design, and reliable circuit implementation. It significantly improves the control accuracy and operational stability of the system, and has outstanding substantive features and significant progress.

[0069] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made within the scope of protection of this patent should still fall within the scope of this patent. Furthermore, the technical features, technical features and technical solutions, and technical solutions in this invention can be freely combined and used.

Claims

1. A control signal conversion device for aircraft strength testing, characterized in that, include: Power supply module, EtherCAT coupler module, and digital-to-analog converter module; The DC output terminal of the power module is connected to the power input terminal of the EtherCAT coupler module and the power input terminal of the digital-to-analog converter module, respectively. The Ethernet input terminal of the EtherCAT coupler module is connected to an external PC / PLC controller, and the E-Bus interface of the EtherCAT coupler module is connected to the E-Bus interface of the digital-to-analog converter module. The analog output of the digital-to-analog converter module is connected to an external actuator; The power module is used to convert external AC power into DC power and provide operating power for the EtherCAT coupler module and the digital-to-analog converter module. The EtherCAT coupler module is used to receive EtherCAT protocol digital signals from the PC / PLC controller through the Ethernet input terminal of the EtherCAT coupler module, process the EtherCAT protocol and allocate power, and forward the digital signals to the digital-to-analog converter module through the E-Bus bus. The digital-to-analog converter module is used to receive digital signals via the E-Bus bus, convert the digital signals into ±10V analog voltage signals, and output them to an external actuator through the analog output terminal of the digital-to-analog converter module.

2. The aircraft strength test control signal conversion device according to claim 1, characterized in that, The EtherCAT coupler module includes: Ethernet input interface, Ethernet output interface, Ethernet physical layer chip, EtherCAT slave controller, configuration storage unit, E-Bus interface driver circuit, E-Bus connector, power supply circuit, power output terminal and indicator light circuit; The Ethernet input interface is connected to the receive channel of the Ethernet physical layer chip, the Ethernet output interface is connected to the transmit channel of the Ethernet physical layer chip, and the Ethernet physical layer chip is connected to the EtherCAT slave controller through an independent interface MII. The configuration storage unit is connected to the configuration pin of the EtherCAT slave controller, and the data bus of the EtherCAT slave controller is connected to the input terminal of the E-Bus interface driver circuit. The output terminal of the E-Bus interface driver circuit is connected to the data pin of the E-Bus connector; The power supply circuit includes a filter / protection circuit and a DC-DC converter. The input terminal of the filter / protection circuit is connected to an external 24V DC power supply, and the output terminal of the filter / protection circuit is connected to the input terminal of the DC-DC converter. The output terminal of the DC-DC converter is connected to the power supply pins of the Ethernet physical layer chip, the EtherCAT slave controller, and the E-Bus interface driver circuit, respectively. The power output terminal is connected in parallel with the input terminal of the filter / protection circuit to provide a 24V external power supply to the digital-to-analog converter module. The indicator light circuit is connected to the status output pin of the EtherCAT slave controller and the power monitoring pin of the E-Bus interface driver circuit, respectively. The Ethernet input interface is used to receive digital signals, and the Ethernet output interface is used to cascade the next slave device. The Ethernet physical layer chip is used to transmit and receive 100BASE-TX physical layer signals; The EtherCAT slave controller is used to process EtherCAT protocol frames and extract or insert process data; The configuration storage unit is used to store the module's operating parameters and configuration information; The E-Bus interface driver circuit is used to convert the 3.3V data signal output by the EtherCAT slave controller into a 5V E-Bus bus level; The E-Bus connector is used to provide data signals, clock signals and 5V logic power to the digital-to-analog converter module via a data line; The power supply circuit is used to convert the external 24V power supply into a 5V logic power supply and to power the various circuits inside the module. The power output terminal is used to provide 24V peripheral device power to the digital-to-analog converter module; The indicator light circuit is used to display the module's power status, operating status, error status, E-Bus status, and network link status.

3. The aircraft strength test control signal conversion device according to claim 2, characterized in that, The power supply circuit includes: Fuse F1, TVS diode D1, common mode inductor L1, electrolytic capacitor C1, reverse polarity protection diode D2, filter capacitor C2, and ferrite bead FB1; The input terminal of the fuse F1 is connected to a +24V power supply, the output terminal of the fuse F1 is connected to one end of the TVS diode D1 and the first input terminal of the common mode inductor L1, and the other end of the TVS diode D1 is connected to the power ground GND. The first output terminal of the common-mode inductor L1 is connected to the positive terminal of the electrolytic capacitor C1. The second output terminal of the common-mode inductor L1 is connected to the input terminal of an external voltage regulator chip via the ferrite bead FB1. The negative terminal of the electrolytic capacitor C1 is connected to the power ground GND. The anode of the reverse polarity protection diode D2 is connected to the positive terminal of the electrolytic capacitor C1, and its cathode is connected to the positive terminal of the filter capacitor C2 and the input terminal of the voltage regulator chip. The negative terminal of the filter capacitor C2 is connected to the power ground GND. The fuse F1 is used to blow and protect the subsequent circuits when an overcurrent fault occurs in the circuit. The TVS diode D1 is used to suppress transient overvoltage surges on the power line; The common-mode inductor L1 is used to suppress common-mode electromagnetic interference on the power line; The electrolytic capacitor C1 is used for primary filtering and energy storage of the input power supply. The reverse polarity protection diode D2 is used to prevent damage to subsequent circuits when the power supply polarity is reversed. The filter capacitor C2 is used for secondary high-frequency filtering of the power supply. The magnetic bead FB1 is used to provide input power.

4. The aircraft strength test control signal conversion device according to claim 2, characterized in that, The DC-DC converter includes: Start-up resistor R, PWM controller, MOSFET Q1, transformer T1, and rectifier diode D3; One end of the start-up resistor R is connected to the +24V_IN power supply, the other end of the start-up resistor R is connected to the start-up pin of the PWM controller, the drive output pin of the PWM controller is connected to the gate of the MOSFET Q1, the drain of the MOSFET Q1 is connected to the same-name terminal of the primary winding of the transformer T1, and the source of the MOSFET Q1 is connected to the primary ground GND_PRI. The primary winding of transformer T1 with the opposite name is connected to the +24V_IN power supply, and the secondary winding of transformer T1 with the same name is connected to the anode of rectifier diode D3. An isolation barrier is provided between the primary side and the secondary side of the transformer T1 to achieve electrical isolation between the primary ground GND_PRI and the secondary grounds GND_SEC and GND_ISO. The starting resistor R is used to provide the initial operating current for the PWM controller during startup; The PWM controller is used to generate PWM drive signals and control the switching state of the MOSFET Q1; The MOSFET Q1 is used to turn on and off in a high-frequency manner according to the PWM drive signal, and to generate alternating current on the primary side of the transformer T1. The transformer T1 is used to realize voltage transformation, energy transmission and primary-secondary electrical isolation; The rectifier diode D3 is used to rectify the high-frequency AC voltage output from the secondary side of the transformer.

5. The aircraft strength test control signal conversion device according to claim 4, characterized in that, The DC-DC converter further includes: Filtering network and feedback optocoupler; The output of the filter network is connected to +5V_OUT, and the input of the filter network is connected to the cathode of the rectifier diode D3. The input terminal of the feedback optocoupler is connected to the output terminal of the filter network, and the output terminal of the feedback optocoupler is connected to the feedback pin of the PWM controller. The filtering network is used to smooth the pulsating DC voltage after rectification and output a stable +5V_OUT DC voltage. The feedback optocoupler is used to isolate and feed back the output voltage sampling signal to the PWM controller in order to achieve closed-loop voltage regulation control.

6. The aircraft strength test control signal conversion device according to claim 2, characterized in that, The E-Bus interface driver circuit includes: Level shifting / buffering chip and E-Bus connector; One side of the level conversion / buffer chip is connected to the 3.3V data line of the EtherCAT slave controller, the other side of the level conversion / buffer chip is connected to the data pin of the E-Bus connector, the power supply pin of the level conversion / buffer chip is connected to the 5V_E-BUS power supply, and the ground pin of the level conversion / buffer chip is connected to digital ground GND. The first pin of the E-Bus connector is connected to the 5V E-BUS power supply, the second pin is connected to the digital ground GND, the third pin is connected to the DATA0 signal line, the fourth pin is connected to the DATA1 signal line, the fifth pin is connected to the CLK clock line, the sixth pin is connected to the SELECT selection line, the seventh pin is connected to the +24V OUT external power supply, and the eighth pin is connected to the GND 24V external power supply ground. The level conversion / buffering chip is used to convert the 3.3V data signal level output by the EtherCAT slave controller to the 5V E-Bus bus level and to buffer and drive the signal. The E-Bus connector is used to provide the digital-to-analog converter module with 5V logic power, data signal DATA0, data signal DATA1, clock signal CLK, chip select signal SELECT, 24V peripheral power and corresponding power ground through the various pins of the E-Bus connector.

7. The aircraft strength test control signal conversion device according to claim 1, characterized in that, The digital-to-analog conversion module includes: Communication controller / FPGA, digital isolator, isolated DC-DC power supply, multiple digital-to-analog converters (DACs), multiple output amplification and protection circuits, output terminal blocks and external power input interface; The input terminal of the communication controller / FPGA is connected to the E-Bus input interface, and the output terminal of the communication controller / FPGA is connected to the primary side of the digital isolator via a parallel port or a high-speed SPI bus. The secondary side of the digital isolator is connected to the digital input terminals of multiple digital-to-analog converters (DACs) via an isolation SPI bus. The analog output of each of the digital-to-analog converters (DACs) is connected to the input of a corresponding output amplification and protection circuit. The output terminals of the plurality of output amplification and protection circuits are respectively connected to the corresponding pins of the output terminal block; The input terminal of the isolated DC-DC power supply is connected to the +5V_IN power supply, and the output terminal of the isolated DC-DC power supply is connected to the digital-to-analog converter (DAC) and the output amplification and protection circuit, respectively. The communication controller / FPGA is used to parse the E-Bus protocol, perform data buffering and allocation, and implement DC clock synchronization management; The digital isolator is used to achieve electrical isolation between the communication side and the analog side, ensuring the security of signal transmission; The isolated DC-DC power supply is used to convert the input +5V power supply into ±15V and +5V analog power supplies that are electrically isolated from the communication side, providing independent power for the digital-to-analog conversion and output circuits. The digital-to-analog converter (DAC) is used to convert the received digital signal into a high-precision analog voltage signal. The output amplification and protection circuit is used to amplify, filter, and protect the analog voltage output by the DAC. The output terminal block is used to output the converted analog voltage signal to external test control equipment.

8. The aircraft strength test control signal conversion device according to claim 7, characterized in that, The digital-to-analog conversion module further includes: External power input interface and diagnostic feedback circuit; The external power input interface is connected to +24V and GND; The input terminals of the diagnostic feedback circuit are respectively connected to the current detection points of the output amplification and protection circuit, and the output terminals of the diagnostic feedback circuit are connected to the fault feedback pin of the communication controller / FPGA through optocoupler isolation. The external power input interface is used to receive an external 24V power supply to power the output stage circuit. The diagnostic feedback circuit is used to monitor the output current of each channel in real time, and feeds back to the communication controller / FPGA through optocoupler isolation when an overcurrent or short circuit fault occurs.

9. The aircraft strength test control signal conversion device according to claim 7, characterized in that, The digital-to-analog converter (DAC) includes: DAC chip, low-pass filter network, and operational amplifier; The digital input terminal of the DAC chip is connected to the isolated SPI bus, the REF+ pin of the DAC chip is connected to the precision reference voltage source, the REF- pin of the DAC chip is connected to analog ground, and the VOUT pin of the DAC chip is connected to the input terminal of the low-pass filter network. The low-pass filter network includes a first resistor R1 and a first capacitor C1. One end of the first resistor R1 is connected to the VOUT pin of the DAC chip, and the other end of the first resistor R1 is connected to one end of the first capacitor C1 and the non-inverting input of the operational amplifier. The other end of the first capacitor C1 is connected to analog ground. The inverting input terminal of the operational amplifier is connected to the output terminal of the operational amplifier via a feedback resistor, and the positive and negative power supply pins of the operational amplifier are connected to +15V_ISO and -15V_ISO, respectively. The DAC chip is used to convert digital signals input from the isolated SPI bus into high-precision analog voltage signals. The low-pass filter network is used to filter out high-frequency noise components in the DAC output signal; The operational amplifier is used to amplify the filtered analog voltage in phase, adjusting the voltage range to a standard output of ±10V.

10. The aircraft strength test control signal conversion device according to claim 9, characterized in that, The digital-to-analog conversion module also includes an output protection and current detection amplifier circuit; The output terminal of the operational amplifier is connected to the input terminal of the output protection and current detection amplifier circuit, which is used to limit the current, clamp the overvoltage, and detect and protect the output signal. The output protection and current detection amplifier circuit includes an output protection circuit, a current detection amplifier circuit, an overcurrent detection branch, and a fault feedback branch connected in sequence. The output protection circuit is used to limit the current and clamp the overvoltage of the output signal. The current detection amplifier circuit is used to sample and amplify the output current; The overcurrent detection branch is used to compare the amplified current signal with a preset threshold to determine whether an overcurrent or short circuit fault has occurred. The fault feedback branch is used to send the fault flag as the result of the fault feedback to the communication controller / FPGA.

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