A pitch signal adjusting circuit and a three-path feedback redundant control method for a controllable pitch propeller

Abstract

The application discloses a pitch signal adjusting circuit and a three-way feedback redundancy control method for a variable pitch propeller, comprising a power supply circuit, a pitch signal collecting and adjusting circuit and a three-way feedback redundancy control module; the three-way feedback redundancy control module receives three-way pitch feedback current signals respectively and is configured to execute a three-way feedback redundancy control method; the method comprises safety threshold judgment, weighted voting, consistency detection, majority voting, dynamic selection, stability judgment, recursive average filtering and median filtering algorithms executed in a preset rule sequence, and according to the deviation, change rate and fluctuation state of the three-way signals, effective signals are dynamically selected to participate in the closed-loop control of the variable pitch propeller, or the pitch is locked and an alarm is given when all the signals are abnormal. The three-way pitch feedback signals of the variable pitch propeller are independent of each other and do not interfere with each other, the three-way pitch signals are processed through the method, the reliability of the variable pitch propeller system is improved, and the method is suitable for popularization and use in a pitch control system of the variable pitch propeller.

Description

Technical Field

[0001] This invention relates to the field of electrical control technology, and in particular to a pitch signal adjustment circuit for a controllable propeller and a three-way feedback redundancy control method for use in a ship propulsion system. Background Technology

[0002] The pitch signal of the controllable pitch propeller is one of the most critical pieces of information in the controllable pitch propeller ship propulsion control system. Its accuracy, stability, and transmission reliability directly determine whether the controllable pitch propeller device can work properly and the safety of ship navigation.

[0003] Currently, both domestically and internationally, a triple potentiometer is commonly used to acquire pitch feedback signals for controllable pitch propellers. This allows for the simultaneous acquisition of three independent feedback signals, which are transmitted as analog voltages or currents. The pitch signal includes pitch control feedback and pitch indication feedback signals, which are independent and powered by separate power supplies. In essence, the triple potentiometer acquires the pitch mechanical angle information, which is then transmitted to the pitch feedback circuit. After adjustment by the circuitry on the feedback circuit board, the pitch feedback signal is ultimately transmitted outward as an analog voltage or current. The first pitch signal feedback participates in the closed-loop pitch control of the controllable pitch propeller system and is the core component of the controllable pitch propeller control. If this signal fails, the automatic control function of the controllable pitch propeller system will be disabled. The second pitch signal feedback outputs a pitch indication feedback signal to the outside, used for displaying the controllable pitch signal in various parts of the control room. The third pitch signal feedback is generally a backup signal or a pitch display signal in the engine room. If the first or second pitch feedback fails, it can be temporarily replaced by manual adjustment to ensure the normal operation of the controllable pitch propeller system. The three pitch feedbacks are independent of each other and do not interfere with each other. They each have their own independent power supply. However, the presence of multiple external power supplies makes it easy for incorrect power line connections to damage the feedback circuits.

[0004] Based on the search and analysis, the existing technology mainly has the following shortcomings:

[0005] For example, patent document (CN113353223A) discloses an intelligent pitch feedback board for a controllable pitch propeller. This board controls the current output via an SPI bus and uses a combination of three potentiometers and buttons for one-button setting, solving the problems of large temperature drift and complex five-potentialmeter setting in traditional analog circuits. It also adds alarm functions for disconnection and out-of-range operation. However, this solution only addresses the digital transformation of a single-channel feedback board and does not involve redundant collaborative processing logic between multiple independent feedback signals. It also fails to address the hardware protection issue of easily reversing multiple external power supplies in real-world ship applications, which can lead to circuit board burnout. When a single signal fails, it still relies on manual switching or simple backup, lacking a dynamic intelligent arbitration mechanism.

[0006] The patent document (CN110844030A) discloses a method for acquiring and processing pitch feedback signals. This patent adjusts the voltage signal to a 4-20mA current at the pitch transmitter side and transmits it over a long distance to the control box. Then, it uses a PLC combined with touchscreen structural information for secondary adjustment, effectively solving the problems of poor anti-interference capability during long-distance voltage transmission and zero-position shifting on the analog board. However, this solution focuses on modifying the signal transmission link and calibrating the PLC end, without disclosing a hardware power supply error-proofing design for the three independent feedback signals, and further without providing a software-level redundant voting and filtering algorithm based on multiple thresholds and multiple states (consistency, rate of change, fluctuation amplitude, historical fault memory). In complex sea conditions or when sensor aging causes multiple signals to drift or oscillate simultaneously, it still cannot achieve high-reliability closed-loop control degradation or safety interlocking.

[0007] In summary, existing technologies have significant gaps in multi-channel power supply security, independent uncoupled setting of forward and reverse ranges, and multi-channel dynamic redundancy arbitration algorithms. When external power supply wiring is incorrect, or single / multi-channel signals drift, abruptly change, or experience high-frequency fluctuations, traditional systems are prone to control logic chaos, zero-position inaccuracy, and even controllable pitch propeller malfunction. Therefore, a comprehensive solution integrating hardware protection, precise conditioning, and intelligent redundancy algorithms is urgently needed. This solution employs a power protection circuit to provide power to the three pitch feedback channels separately. A triple potentiometer is used to collect the pitch feedback signals, which are then adjusted and calibrated by three independent feedback circuit boards before being output as three separate pitch feedback signals. The three pitch feedback current signals are transmitted to the controllable pitch propeller pitch controller via a signal isolation module that splits the signal into two paths. Within the pitch controller, a redundancy algorithm is applied to the three pitch feedback signals, improving the reliability of the controllable pitch propeller closed-loop control system. Summary of the Invention

[0008] The technical problem this invention aims to solve is to provide a controllable pitch propeller pitch signal adjustment circuit and a three-way feedback redundancy control method. Utilizing the independent three-way pitch feedback of the controllable pitch propeller device, and addressing the issue of multiple external power supplies in the original circuit, which are prone to wiring faults, a power signal protection circuit is employed to prevent damage to the feedback circuit due to wiring errors. Simultaneously, the controllable pitch propeller pitch signal acquisition and adjustment circuit outputs multiple pitch feedback current signals. These signals are then collected by a signal isolation module, and a multi-channel signal redundancy algorithm is performed internally within the controllable pitch propeller pitch controller. This improves the reliability of the controllable pitch propeller device control and makes it suitable for widespread application in controllable pitch propeller ship pitch feedback systems.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A pitch control propeller pitch signal adjustment circuit and a three-way feedback redundancy control method are disclosed, comprising: a power supply circuit, a pitch signal acquisition and adjustment circuit, and a three-way feedback redundancy control module. The power supply circuit consists of a power protection circuit and a power voltage regulation and isolation circuit, used to prevent reverse polarity connection of the external power supply, and simultaneously stabilize the external power supply voltage to provide the required power signals for each of the three pitch feedback circuits. The pitch signal acquisition and adjustment circuit consists of a signal acquisition circuit, a filtering and following circuit, a zero-point adjustment circuit, a forward / reverse range adjustment circuit, and a current signal output circuit, used to receive the pitch mechanical angle signal from the pitch potentiometer, and through signal filtering and following, the zero-point adjustment circuit, and the forward / reverse range adjustment circuit, realize the pitch adjustment. The propeller adjusts the output voltage signal range at maximum reverse pitch, zero pitch, and maximum forward pitch. Simultaneously, a current signal output circuit converts the adjusted pitch feedback voltage signal into a current signal output at the corresponding range. The three-way feedback redundancy control module receives the three pitch feedback current signals and is configured to execute a three-way feedback redundancy control method. The method includes safety threshold judgment, weighted voting, consistency detection, majority voting, dynamic selection, stability judgment, recursive average filtering, and median filtering algorithms executed sequentially according to preset rules. Based on the deviation, rate of change, and fluctuation status of the three signals, effective signals are dynamically selected to participate in the pitch control propeller closed-loop control, or the pitch is locked and an alarm is triggered when all signals are abnormal.

[0010] Furthermore, the power supply circuit includes a reverse connection protection circuit and a DC-DC power isolation chip; the positive and negative terminals of the external +24VDC power supply can be arbitrarily connected to the corresponding terminals, and the standard polarity +24VDC voltage is output through the reverse connection protection circuit. The input terminal of the DC-DC power isolation chip is connected to the +24VDC voltage, and its output terminal outputs +15VDC, 0V, and -15VDC voltages respectively, providing bipolar operating power for the subsequent operational amplifier; the power supply circuit also includes a reference power chip, whose input terminal is connected to +15VDC and 0V voltages, and outputs a +10VDC reference voltage to power the pitch potentiometer.

[0011] Furthermore, the pitch signal acquisition and adjustment circuit sends a reference voltage signal to the pitch potentiometer through the reference power chip, and simultaneously receives the pitch feedback voltage signal output by the potentiometer. This signal enters the filter follower circuit, and after RC filtering, it is connected to the negative input terminal of the operational amplifier for inverting proportional amplification and follower processing, outputting a unipolar pitch feedback follower negative voltage signal. This signal enters the zero position and forward / reverse range adjustment circuit, and is connected in parallel with the positive voltage signal output by potentiometer P3, and connected to the negative input terminal of the operational amplifier to form an inverting proportional amplification adder circuit.

[0012] Furthermore, the pitch signal acquisition and adjustment circuit, at the zero pitch position, outputs zero voltage by adjusting potentiometer P3; potentiometer P1 adjusts the negative voltage signal output value at the maximum reverse pitch, wherein the diode D1 circuit connected to potentiometer P1 ensures that potentiometer P1 can only adjust the negative voltage output value, that is, within the range of zero pitch and reverse pitch, the range of the reverse pitch signal is adjusted; potentiometer P2 is used to adjust the range of the positive voltage signal output when the pitch changes from zero pitch to maximum forward pitch, wherein the diode circuit D2 connected to potentiometer P2 ensures that potentiometer P2 can only adjust the positive voltage output value, that is, potentiometer P2 can only adjust the range of the forward pitch signal; after the forward and reverse ranges are independently adjusted by potentiometers P1 and P2, a bipolar pitch feedback voltage signal is output.

[0013] Furthermore, the current signal output circuit connects the received bipolar pitch feedback voltage signal in parallel with the adjustable positive voltage signal output by potentiometer P4, and together they enter the inverting proportional amplifier circuit. This transforms the bipolar pitch feedback voltage signal into a unipolar negative voltage signal output, which is then amplified by the inverting proportional amplifier circuit to output a positive voltage signal to the base of the transistor. The change in the pitch feedback signal causes a change in the base voltage, resulting in a change in the base current, which in turn controls the current flowing through the transistor. In the current signal conditioning circuit, the current output adopts a common-source design, meaning that the current output from the power supply is output to the external load through a current-limiting resistor, then flows back into the collector of the transistor, exits through the emitter, and returns to the power supply through the current-limiting resistor. The negative terminal is the common source of the output current. By adjusting potentiometer P1 or P2, the voltage signal applied to the base of the transistor is adjusted, thereby controlling the current signal flowing through the transistor and ultimately determining the current value output to the external load. When the pitch feedback changes from full reverse to full forward, a corresponding 4~20mA current signal is output. At the zero thrust pitch position of the controllable pitch propeller, the pitch feedback current signal can be adjusted to 12mA output by adjusting the voltage signal of potentiometer P4. When the pitch of the controllable pitch propeller is at the maximum forward pitch position, the maximum pitch feedback current output of 20mA is adjusted by adjusting potentiometer P2. When the pitch of the controllable pitch propeller is at the maximum reverse pitch position, the minimum pitch feedback current output of 4mA is adjusted by adjusting potentiometer P1.

[0014] Furthermore, the first rule of the three-way feedback redundancy control method is a weighted voting rule: the priority of the first pitch feedback signal is predefined as I, the priority of the second is II, and the priority of the third is III; in the fault-free state, the corresponding signals are selected to participate in the pitch control propeller closed-loop control in order of priority from high to low.

[0015] Furthermore, the second rule of the three-way feedback redundancy control method is a safety threshold rule: real-time monitoring of the three feedback signals; when the amplitude of any one signal exceeds the preset safety threshold θ1, the signal is determined to be a fault signal and forcibly removed, and does not participate in closed-loop control; the lower priority signal of the removed signal is automatically promoted to replace it; if all three signals exceed θ1, the closed-loop control is determined to be in failure, the pitch position is locked and a fault alarm is output.

[0016] Furthermore, the third rule of the three-way feedback redundancy control method is a consistency detection and majority voting rule: calculate the pairwise difference between the three signals; if the difference between a certain signal and the other two signals is greater than the preset deviation threshold θ2, then the signal is determined to be a fault signal and recorded; the condition for clearing the fault record in the register is that the signal recovers and the difference between it and the other two signals is less than θ2 again; the remaining two consistent signals are sorted according to the weighted voting rule and participate in the control.

[0017] Furthermore, the fourth rule of the three-way feedback redundancy control method is a dynamic selection rule: when the difference between any two of the three signals is greater than θ2 and there are unrecovered channels in the historical fault records, the unit time change of the remaining two signals at the moment when the difference exceeds the threshold is monitored; if the change of only one signal exceeds the unit time change threshold θ3, then that signal is determined to be a sudden fault signal and is removed, and the other normal signal participates in the control; if the change of both signals exceeds θ3 but is still within the safety threshold θ1, then the median filtering algorithm is called to select the median of the three signals to participate in the control, and an alarm is triggered to indicate an inconsistency fault.

[0018] Furthermore, the fifth to seventh rules of the three-way feedback redundancy control method are stability and filtering fusion rules: detect the fluctuation amplitude of the three signals, and when the fluctuation of one signal exceeds the fluctuation threshold θ4, that signal is removed, and the remaining two signals are selected according to priority; when the fluctuation of two signals exceeds θ4, the only stable signal is selected to participate in the control; when the fluctuation of all three signals exceeds θ4, recursive average filtering is first performed on the three signals respectively, and then the median filtering algorithm is applied; if the fluctuation amplitude of the median after filtering does not exceed the median fluctuation threshold θ5 within a unit time, the median is output to participate in the control; otherwise, the closed loop is determined to be in failure, the pitch is locked, and an alarm is triggered; when the fluctuation of any signal exceeds θ4, a fluctuation fault alarm is simultaneously output.

[0019] Compared with the prior art, the present invention has the following significant advantages: This invention is based on the premise that the three pitch feedback signals of a controllable pitch propeller are mutually independent and do not interfere with each other. On this basis, it utilizes redundant algorithms such as safety threshold, consistency detection, majority voting, weighted voting, dynamic selection, recursive average filtering, and median filtering to process the three pitch signals, thereby improving the reliability of the controllable pitch propeller system. Its feedback circuit design is simple and reliable, and the redundant algorithms are clear and easy to understand. At the same time, the power protection function of the circuit board is convenient for practical ship applications and is suitable for widespread use in controllable pitch propeller pitch control systems.

[0020] 1. Significantly improved hardware protection and anti-interference capabilities: The reverse connection protection and DC-DC isolation design at the power supply end completely solves the problem of circuit burnout due to incorrect wiring of multiple power supplies on ships; the common source 4-20mA current output architecture combined with watertight shielded cable transmission greatly reduces the interference of the complex electromagnetic environment of ships on pitch signals.

[0021] 2. Leap in setting accuracy and debugging efficiency: Breaking through the traditional five-potential meter cross-setting mode, it adopts diode-isolated P1 / P2 independent range adjustment for forward and reverse movement and P3 / P4 zero / reference fine adjustment to achieve decoupled setting of "forward-reverse-zero position". The debugging process is intuitive and interference-free, and the zero position changes are eliminated.

[0022] 3. Seven-order progressive redundancy algorithm ensures ultimate reliability: A pioneering seven-rule algorithm chain for controllable pitch propeller operation, consisting of "weighted priority → absolute safety threshold → relative consistency → dynamic selection of rate of change → stability grading → recursive averaging + median fusion → secondary verification locking." This covers the entire fault spectrum, including single-path drift, dual-path abrupt changes, and three-path oscillations, achieving intelligent and seamless switching from "fault isolation - degraded operation - median fault tolerance - safety locking," significantly improving closed-loop control availability and navigation safety compared to existing technologies.

[0023] 4. Highly adaptable to real-world ship applications and promotion: The circuit structure is modular and standardized, and the algorithm logic is clear and can be implemented through embedded programming. It can run independently in the PLC / controller without relying on a complex host computer, which facilitates the retrofitting of old controllable pitch propeller systems and integration with new-generation intelligent propulsion systems. Attached Figure Description

[0024] Figure 1 This is a block diagram of the three-way pitch feedback redundancy control principle of the present invention; Figure 2 This is the power supply circuit diagram of the present invention; Figure 3 This is a circuit diagram of the pitch signal acquisition and adjustment circuit of the present invention; Figure 4 This is a schematic diagram of the redundancy control rule 1 of the present invention; Figure 5 This is a schematic diagram of redundancy control rule 2 of the present invention; Figure 6 This is a schematic diagram of redundancy control rule 3 of the present invention; Figure 7 This is a schematic diagram of the redundancy control rule 4 of the present invention; Figure 8 This is a schematic diagram of redundancy control rules 5 to 7 of the present invention. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0026] The present invention discloses a pitch signal adjustment circuit for a controllable pitch propeller and a three-way feedback redundancy control method. Based on three independent pitch feedback signals, the circuit is processed by a multi-way signal redundancy algorithm and participates in the closed-loop control of the pitch signal of the controllable pitch propeller. At the same time, a power protection circuit is adopted to increase the safety of the power signal wiring.

[0027] Example 1: Figures 1 to 8This paper presents a method for improving the reliability of pitch feedback signals in controllable propellers. This method is based on transmitting three independent, non-interfering pitch feedback signals to a pitch controller and employs a redundant pitch feedback design. The circuit consists of three parts: a power supply circuit, a pitch signal acquisition and adjustment circuit, and a three-way feedback redundancy control method. The power supply circuit comprises a power protection circuit and a voltage regulation and isolation circuit to prevent reverse polarity of multiple external power supplies from damaging circuit board components. Simultaneously, the voltage regulation and isolation electronic components stabilize fluctuations in the external power supply voltage, providing isolation and stable power to the three pitch feedback circuits. The pitch signal acquisition and adjustment circuit consists of a signal acquisition circuit, a filtering and following circuit, a zero-point adjustment circuit, a forward / reverse range adjustment circuit, and a current signal output circuit. It receives the angle signal from the pitch potentiometer, filters and follows the signal, and adjusts it. The circuitry adjusts the output voltage signal range of the controllable pitch propeller at maximum reverse pitch, zero pitch, and maximum forward pitch. Simultaneously, it converts the adjusted pitch feedback voltage signal into a current signal corresponding to the range, transmitting a 4-20mA pitch feedback current signal. Specifically, it outputs a 4mA current signal at the maximum reverse pitch position, a 12mA current signal at the zero thrust position, and a 20mA current signal at the maximum forward pitch position. A three-way feedback redundancy control method receives three independent pitch feedback signals, compares them in the controller, and performs redundancy processing on the feedback signals through a redundancy control algorithm, improving the system's operational reliability.

[0028] The power supply circuit is connected to an external +24VDC power supply. The positive and negative terminals of the power supply can be arbitrarily connected to the corresponding terminals U1-1 and U1-2, U2-1 and U2-2, and U3-1 and U3-2. The three pitch feedback signal adjustment circuits are identical and independent. Therefore, the first pitch feedback signal adjustment circuit will be used as an example for explanation. An external power supply is connected to the external power terminals U1-1 and U1-2 of the first pitch feedback board. After passing through the reverse connection protection circuit, a +24VDC voltage is output at the output terminals U1o+ and U1o-. The output terminals U1o+ and U1o- are connected to the input terminals of the power isolation chip DC-DC2415-1. The output terminals P15-1, M1, and N15-1 of the power isolation chip output +15VDC, 0V, and -15VDC voltages, respectively. The DC2415-1 terminals P15-1 and N15-1 output +15VDC and -15VDC voltage signals to provide operating power for all operational amplifiers in the first pitch feedback board. These are connected to the power supply terminals P-1 and N-1 of the four operational amplifiers LM124-1, respectively. At the same time, the output terminals P15-1 and M-1 of the power isolation chip DC2415-1 are connected to the input terminal P10-1 and ground terminal M-1 of the reference power chip AD581-1. The AD581-1 output terminal P10-1 and ground terminal M-1 output a +10VDC reference voltage. The signal acquisition circuit sends a +10VDC reference voltage signal to both ends of the pitch potentiometer through the output terminal P10-1 and ground terminal M-1 of the reference power chip AD581-1. Simultaneously, the pitch feedback voltage signal VIN is output from the middle terminal of the pitch potentiometer. This signal enters the filter follower circuit, is filtered by the RC circuit, and then connected to the negative input port 2-1 of the first operational amplifier of the LM124-1 four-channel operational amplifier for inverting proportional amplification and follower processing. The output port 1 of the first operational amplifier of the LM124-1 outputs a unipolar pitch feedback follower negative voltage signal VI-1. This signal enters the zero-position and forward / reverse range adjustment circuit, is connected in parallel with the positive voltage signal output by potentiometer P3-1, and is connected to the negative input terminal 6-1 of the second operational amplifier of the LM124-1 operational amplifier chip, forming an inverting proportional amplification and addition circuit. At the zero-thrust pitch position, by adjusting potentiometer P3-1, the second operational amplifier of the LM124-1... The output voltage signal VI-1 at the operational amplifier output port 7 is zero. Potentiometer P1-1 amplifies the output voltage in the inverting proportional amplifier adder circuit, adjusting the negative voltage signal output of VI-1 when the pitch is at the maximum reverse position. The diode D1-1 circuit connected to potentiometer P1-1 ensures that potentiometer P1-1 can only adjust the negative voltage amplification output value, thus adjusting the reverse pitch range from zero pitch to the maximum forward pitch. Similarly, potentiometer P2-1 adjusts the positive voltage signal output of VI-1 when the pitch changes from zero pitch to the maximum forward pitch. The diode D2-1 circuit connected to potentiometer P2-1 ensures that potentiometer P2-1 can only adjust the positive voltage amplification output value, meaning potentiometer P2-1 can only adjust the range from zero thrust to the forward pitch. After adjustment by potentiometers P1-1 and P2-1, a bipolar adjustable pitch feedback voltage signal is output.The current signal output circuit receives bipolar positive and negative voltage signals VⅡ-1, which are connected in parallel with the positive voltage signal output from potentiometer P4-1. Together, they enter the third operational amplifier of the LM124-1 operational amplifier chip, forming an inverting proportional amplifier circuit. By adjusting the positive voltage signal output from potentiometer P4-1, the bipolar pitch feedback voltage signal connected in parallel is output through the third operational amplifier output port 8 of the LM124-1 operational amplifier chip, resulting in a unipolar negative voltage signal VⅢ-1. This signal then enters the negative input terminal 13 of the fourth operational amplifier of the LM124-1 operational amplifier chip, and after passing through the inverting proportional amplifier circuit, outputs a positive voltage signal. The pitch feedback signal VⅣ-1 is connected to the base of transistor TR-1. Changes in the pitch feedback signal cause changes in the base voltage, which in turn changes the base current. This controls the change in the current flowing through transistor TR-1. In the current signal conditioning circuit, the current output adopts a common-source design. That is, the current output from the power supply is output to the external load through the current-limiting resistor, then flows back into the collector of transistor TR-1, flows out through the emitter of transistor TR-1, and flows back to the negative terminal M-1 of the power supply through the current-limiting resistor. In other words, the output current is common-source. The pitch feedback current signal Aout-1 is output through terminals IOUT1-1 and IOUT1-2. When the controllable pitch propeller pitch is at zero thrust pitch, adjusting potentiometer P4-1 controls the output value of the pitch feedback current signal Aout-1 to 12mA. When the controllable pitch propeller pitch is at the maximum forward pitch position, adjusting potentiometer P2-1 makes the maximum output value of the pitch feedback current signal Aout-1 20mA. When the controllable pitch propeller pitch is at the maximum reverse pitch position, adjusting potentiometer P1-1 makes the maximum output value of the pitch feedback current signal Aout-1 4mA. Therefore, by adjusting potentiometers P1-1, P2-1, and P4-1, the magnitude of the pitch feedback current signal Aout-1 can be determined when the controllable pitch propeller pitch is at maximum reverse, maximum forward, and zero thrust, respectively. As the pitch changes from full reverse to full forward, a corresponding 4~20mA pitch feedback current signal is output. Example 2: A three-way pitch feedback redundancy control method, including algorithms such as safety threshold, consistency detection, majority voting, weighted voting, dynamic selection, recursive average filtering, and median filtering, is implemented in the following order: First rule: weighted voting algorithm. Because the three pitch feedback signals are completely independent, the first pitch feedback signal is prominently displayed in the control room, so its weight is defined as the highest. The second pitch feedback signal is used for display in the engine room, so its weight is defined as the lowest. The third pitch feedback signal is not used for pitch display, so its weight is defined as the lowest. The priority order, from highest to lowest, is: first pitch feedback (priority I), second pitch feedback (priority II), and third pitch feedback (priority III). Pitch feedback signals with higher priority participate in the controllable pitch propeller closed-loop control. The second rule, based on a safety threshold judgment algorithm, states that if any of the three pitch feedback signals exceeds the normal value set within θ1, that signal is considered a fault signal and, regardless of priority, cannot participate in the controllable pitch propeller closed-loop control. Other signals with lower priority automatically have their priority increased by one level and continue to participate in the controllable pitch propeller closed-loop control according to their priority order. If all three pitch feedback signals exceed... If the pitch exceeds the set deviation threshold θ1, and none of the three feedback signals can participate in pitch control, the pitch control closed-loop control fails, the pitch is locked, and a pitch feedback signal fault alarm is output. The third rule, based on consistency detection and majority voting algorithms, calculates the differences between each pair of the three pitch feedback signals: the difference between the first and second feedback signals is Δ1-2 = |F1-F2|, the difference between the first and third feedback signals is Δ1-3 = |F1-F3|, and the difference between the second and third feedback signals is Δ2-3 = |F2-F3|. If the difference is less than the set deviation threshold θ2, it is determined that two signals are consistent, and both pitch feedback signals are positive. Normally, when a certain signal deviates from the other two signals, that is, when the difference between the signal and the other two signals is greater than the set deviation threshold θ1, the pitch feedback signal is determined to be a fault signal and will no longer participate in priority queuing or controllable pitch propeller closed-loop control. At the same time, the fault information of the feedback is recorded in the controller and kept there until the pitch feedback returns to normal and the difference between the signal and the other two feedback signals is less than the set deviation threshold θ2. Then, the fault information recorded in the register is cleared. The remaining two identical feedback signals are sorted according to the priority of rule 1, and the one with higher priority participates in controllable pitch propeller pitch closed-loop control.The fourth rule, based on the dynamic selection algorithm, calculates the difference between each pair of the three pitch feedback signals. If the difference exceeds the set deviation threshold θ2, the pitch feedback signal that is faulty and has not recovered, as recorded by the controller, cannot participate in pitch control. Simultaneously, for the remaining two pitch feedback signals, if the difference exceeds the set threshold θ2, it is further determined whether the change in these two feedback signals exceeds the set unit-time change threshold θ3 for that feedback signal within a unit time. The pitch feedback signal exceeding the unit-time change threshold θ3 is considered a fault signal and will not participate in the controllable pitch propeller closed-loop pitch control. The pitch feedback signal not exceeding the unit-time change threshold θ3 is considered stable and will be considered normal and participate in the controllable pitch propeller closed-loop control. When the difference between the two pitch feedback signals exceeds the deviation setting threshold θ2, if the change in both feedback signals per unit time also exceeds the setting change threshold θ3 (i.e., both feedback signals change simultaneously, and the changed pitch feedback signals are still within the normal pitch threshold θ1 range), then the median of the three feedback signals is selected as the output according to the median filtering algorithm to participate in the pitch closed-loop control. Simultaneously, an alarm is triggered indicating an inconsistency fault in the three pitch feedback signals. The fifth rule uses algorithms such as signal stability threshold judgment, majority voting, and weighted voting to detect the fluctuation of the three pitch feedback signals. When the amplitude of one signal fluctuation exceeds the setting fluctuation threshold θ4, that fluctuating feedback signal cannot participate in the closed-loop control calculation. The remaining two signals whose fluctuations do not exceed the setting fluctuation threshold θ4 participate in the controllable pitch propeller pitch closed-loop control according to the priority order of Rule 1. The sixth rule uses stability threshold... The algorithm uses three pitch feedback signals. If the fluctuation amplitude of two of the feedback signals exceeds the set fluctuation threshold θ4, then the pitch feedback signal whose fluctuation amplitude does not exceed the fluctuation threshold θ4 participates in the controllable pitch propeller closed-loop control. The seventh rule, based on stability safety threshold, recursive averaging filtering, and median filtering algorithms, if all three pitch feedback signals exhibit fluctuations (i.e., the fluctuation amplitude of all three feedback signals exceeds the set fluctuation threshold θ4), then the three pitch feedback signals are first processed by the recursive averaging filtering algorithm. The three pitch feedback signals after individual filtering are then processed by the median filtering algorithm to calculate the median of the three feedback signals. If the calculated median's fluctuation amplitude does not exceed the median fluctuation threshold θ5 within a unit time, then the output median participates in the pitch closed-loop control. If the calculated median's fluctuation amplitude exceeds the median fluctuation threshold θ5 within a unit time, then it does not participate in the pitch closed-loop control, outputs a controllable pitch propeller closed-loop control failure alarm, and locks the pitch. When the fluctuation amplitude of any pitch feedback signal exceeds the set fluctuation threshold θ4, a pitch feedback signal fluctuation fault alarm is output.

[0029] Based on the above rules, redundant algorithms such as safety threshold, consistency detection, majority voting, weighted voting, dynamic selection, recursive average filtering, and median filtering are programmed for the three pitch feedback signals of the controllable pitch propeller, thereby solving the problem of improving the reliability of automatic control of the controllable pitch propeller device at the software level.

[0030] Finally, it should be noted that the above examples are merely a few specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A pitch control propeller pitch signal adjustment circuit and a three-way feedback redundancy control method, characterized in that, include: Power supply circuit, pitch signal acquisition and adjustment circuit, and three-way feedback redundancy control module; The power supply circuit consists of a power protection circuit and a power voltage regulation and isolation circuit, used to prevent reverse polarity of the external power supply and stabilize the external power supply voltage, providing the required power signals for the three pitch feedback circuits. The pitch signal acquisition and adjustment circuit consists of a signal acquisition circuit, a filtering and following circuit, a zero-point adjustment circuit, a forward and reverse range adjustment circuit, and a current signal output circuit. It is used to receive the pitch mechanical angle signal from the pitch potentiometer, and after signal filtering and following, the zero-point adjustment circuit, and the forward and reverse range adjustment circuit, it realizes the adjustment of the output voltage signal range of the pitch control propeller at the maximum reverse pitch, zero pitch, and maximum forward pitch. At the same time, through the current signal output circuit, it is used to convert the adjusted pitch feedback voltage signal into a current signal output of the corresponding range. The three-way feedback redundancy control module receives three pitch feedback current signals respectively and is configured to execute a three-way feedback redundancy control method. The method includes safety threshold judgment, weighted voting, consistency detection, majority voting, dynamic selection, stability judgment, recursive average filtering, and median filtering algorithms executed in sequence according to preset rules. Based on the deviation, rate of change, and fluctuation status of the three signals, effective signals are dynamically selected to participate in the pitch control propeller closed-loop control, or the pitch is locked and an alarm is triggered when all signals are abnormal.

2. The pitch control propeller pitch signal adjustment circuit and three-way feedback redundancy control method according to claim 1, characterized in that, The power supply circuit includes a reverse connection protection circuit and a DC-DC power isolation chip. The positive and negative terminals of an external +24VDC power supply can be arbitrarily connected to the corresponding terminals. The reverse connection protection circuit outputs a standard polarity +24VDC voltage. The input terminal of the DC-DC power isolation chip is connected to the +24VDC voltage, and its output terminal outputs +15VDC, 0V, and -15VDC voltages respectively, providing bipolar operating power for the subsequent operational amplifier. The power supply circuit also includes a reference power chip, whose input terminal is connected to +15VDC and 0V voltages, and outputs a +10VDC reference voltage to power the pitch potentiometer.

3. The pitch control propeller pitch signal adjustment circuit and three-way feedback redundancy control method according to claim 1, characterized in that, The pitch signal acquisition and adjustment circuit sends a reference voltage signal to the pitch potentiometer through a reference power chip, and simultaneously receives the pitch feedback voltage signal output by the potentiometer. The signal enters the filter follower circuit, and after RC filtering, it is connected to the negative input terminal of the operational amplifier for inverting proportional amplification and follower processing, outputting a unipolar pitch feedback follower negative voltage signal. This signal enters the zero position and forward / reverse range adjustment circuit, and is connected in parallel with the positive voltage signal output by potentiometer P3, and connected to the negative input terminal of the operational amplifier to form an inverting proportional amplification adder circuit.

4. The pitch control propeller pitch signal adjustment circuit and three-way feedback redundancy control method according to claim 3, characterized in that, The pitch signal acquisition and adjustment circuit outputs zero voltage at the zero pitch position by adjusting potentiometer P3. Potentiometer P1 adjusts the negative voltage signal output value at the maximum reverse pitch. The diode D1 circuit connected to potentiometer P1 ensures that potentiometer P1 can only adjust the negative voltage output value, that is, adjust the range of the reverse pitch signal within the range of zero pitch and reverse pitch. Potentiometer P2 is used to adjust the range of the positive voltage signal output when the pitch changes from zero pitch to the maximum forward pitch. The diode D2 circuit connected to potentiometer P2 ensures that potentiometer P2 can only adjust the positive voltage output value, that is, potentiometer P2 can only adjust the range of the forward pitch signal. After the forward and reverse ranges are independently adjusted by potentiometers P1 and P2, a bipolar pitch feedback voltage signal is output.

5. The pitch control propeller pitch signal adjustment circuit and three-way feedback redundancy control method according to claim 4, characterized in that, The current signal output circuit connects the received bipolar pitch feedback voltage signal in parallel with the adjustable positive voltage signal output by potentiometer P4, and then they enter the inverting amplifier circuit together. This converts the bipolar pitch feedback voltage signal into a unipolar negative voltage signal output. The signal then passes through the inverting amplifier circuit again to output a positive voltage signal to the base of the transistor. The change in the pitch feedback signal causes a change in the base voltage, which in turn changes the base current, controlling the current flowing through the transistor. In the current signal conditioning circuit, the current output adopts a common-source design. That is, the current output from the power supply passes through a current-limiting resistor to the external load, then flows back into the collector of the transistor, exits through the emitter, and returns to the negative terminal of the power supply through the current-limiting resistor. This means the output current is from the same source. By adjusting potentiometer P1 or P2, the voltage signal applied to the base of the transistor is adjusted, thereby controlling the current signal flowing through the transistor and ultimately determining the current value output to the external load. When the pitch feedback changes from full reverse to full forward, a corresponding 4~20mA current signal is output. At the zero thrust pitch position of the controllable pitch propeller, the pitch feedback current signal can be adjusted to 12mA output by adjusting the voltage signal of potentiometer P4. When the pitch of the controllable pitch propeller is at the maximum forward pitch position, the maximum pitch feedback current output of 20mA is adjusted by adjusting potentiometer P2. When the pitch of the controllable pitch propeller is at the maximum reverse pitch position, the minimum pitch feedback current output of 4mA is adjusted by adjusting potentiometer P1.

6. The pitch control propeller pitch signal adjustment circuit and three-way feedback redundancy control method according to claim 1, characterized in that, The first rule of the three-way feedback redundancy control method is a weighted voting rule: the priority of the first pitch feedback signal is predefined as I, the priority of the second is II, and the priority of the third is III; in the fault-free state, the corresponding signals are selected to participate in the pitch control propeller closed-loop control in order of priority from high to low.

7. The pitch control propeller pitch signal adjustment circuit and three-way feedback redundancy control method according to claim 6, characterized in that, The second rule of the three-way feedback redundancy control method is the safety threshold rule: real-time monitoring of the three feedback signals; when the amplitude of any one signal exceeds the preset safety threshold θ1, the signal is determined to be a fault signal and forcibly removed, and does not participate in the closed-loop control; the lower priority signal of the removed signal is automatically promoted to replace it; if all three signals exceed θ1, the closed-loop control is determined to be in failure, the pitch position is locked and a fault alarm is output.

8. The pitch control propeller pitch signal adjustment circuit and three-way feedback redundancy control method according to claim 7, characterized in that, The third rule of the three-way feedback redundancy control method is the consistency detection and majority voting rule: calculate the pairwise difference between the three signals; if the difference between a certain signal and the other two signals is greater than the preset deviation threshold θ2, then the signal is determined to be a fault signal and recorded; the condition for clearing the fault record in the register is that the signal recovers and the difference between it and the other two signals is less than θ2 again; the remaining two consistent signals are sorted according to the weighted voting rule and participate in the control.

9. The pitch control propeller pitch signal adjustment circuit and three-way feedback redundancy control method according to claim 8, characterized in that, The fourth rule of the three-way feedback redundancy control method is a dynamic selection rule: when the difference between any two of the three signals is greater than θ2 and there are unrecovered channels in the historical fault records, the unit time change of the remaining two signals at the moment when the difference exceeds the threshold is monitored; if the change of only one signal exceeds the unit time change threshold θ3, then that signal is determined to be a sudden fault signal and is removed, and the other normal signal participates in the control; if the change of both signals exceeds θ3 but is still within the safety threshold θ1, then the median filtering algorithm is called to select the median of the three signals to participate in the control, and an alarm is triggered to indicate an inconsistency fault.

10. The pitch control propeller pitch signal adjustment circuit and three-way feedback redundancy control method according to claim 9, characterized in that, The fifth to seventh rules of the three-way feedback redundancy control method are stability and filtering fusion rules: detect the fluctuation amplitude of the three signals, and when the fluctuation of one signal exceeds the fluctuation threshold θ4, that signal is removed, and the remaining two signals are selected according to priority; when the fluctuation of two signals exceeds θ4, the only stable signal is selected to participate in the control. When the fluctuations of all three channels exceed θ4, recursive average filtering is first performed on the three signals respectively, and then the median filtering algorithm is applied. If the fluctuation amplitude of the filtered median does not exceed the median fluctuation threshold θ5 within a unit time, then the median is output to participate in the control; otherwise, the closed loop is deemed to have failed, the pitch is locked, and an alarm is triggered. A fluctuation fault alarm will be output synchronously when any signal fluctuation exceeds θ4.

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