Aircraft non-contact electric pitch changing system and method based on frequency hopping

Abstract

The invention discloses an aircraft non-contact electric pitch changing system and method based on frequency hopping. The system comprises a control end and a receiving end. The control end comprises a first battery, a single-chip microcomputer, a first wireless frequency hopping transmission module and a transmitting antenna, the first battery supplies power to the control end, the single-chip microcomputer is connected with the first wireless frequency hopping transmission module, the wireless frequency hopping transmission module is connected with the transmitting antenna, and the transmitting antenna is connected with the single-chip microcomputer. The receiving end comprises a pitch changing mechanism, a receiving antenna, a second wireless frequency hopping transmission module, a voltage reduction and stabilization module, a second battery and an electric energy wireless transmission module. The second battery supplies power to the receiving end through the electric energy wireless transmission module and the voltage reduction and stabilization module. According to the invention, the hardware design is simplified, the communication synchronization reliability is improved, and efficient half-duplex wireless communication and precise time synchronization are realized.

Description

Technical Field

[0001] This invention belongs to the field of aircraft propeller pitch control technology, specifically relating to a frequency-hopping-based non-contact electric pitch control system and method for aircraft. Background Technology

[0002] With the continuous development of aviation technology, aircraft range has become a critical requirement. Consequently, based on aerodynamic optimization and coordinated control of the power system, higher demands are placed on the accuracy, response speed, and reliability of propeller pitch control. Especially in industrial and military applications, lightweighting, intelligence, and efficiency are key requirements. Traditional mechanical pitch control systems struggle to meet these demands, thus electric pitch control technology has emerged. Electric pitch control, driven by a motor, directly or indirectly controls the propeller blade angle. Compared to traditional methods, it offers advantages such as simple structure, rapid response, and ease of control and integration. However, wired electric pitch control systems typically connect the aircraft fuselage to the high-speed rotating rotor via conductive slip rings, providing power and transmitting signals to the pitch control motor. However, due to the complex operating environment of aircraft, the slip ring material must possess corrosion resistance and wear resistance, and be protected from undue dragging and contact, resulting in significant limitations in its application.

[0003] Compared to methods heavily reliant on slip rings for power and signal transmission, wireless frequency-hopping electric pitch control offers numerous advantages, including contactless, wear-free, flexible, and convenient power and signal transmission. Frequency-hopping transmission technology, with its dynamic frequency switching and frequency-hopping sequence control, ensures reliable data transmission even in environments with multipath fading and strong electromagnetic noise, making it a key technology choice for high-reliability scenarios such as military communications, the Internet of Things, and aerospace. Both the receiving and receiving parties synchronously hop frequencies according to a preset frequency-hopping sequence, and the code logic of software-based data response frame detection and automatic retransmission mechanisms achieves highly reliable data transmission. Structurally, wireless frequency-hopping electric pitch control eliminates the need for complex cable connections, significantly simplifying the pitch control mechanism and reducing aircraft weight, aligning with the modern aviation industry's trend towards lightweight design. In terms of signal transmission, wireless frequency-hopping transmission effectively avoids electromagnetic interference problems associated with cable transmission and specific-frequency electromagnetic wave interference issues associated with ordinary wireless transmission. The signal transmission is stable and highly resistant to interference, allowing for precise control of propeller pitch. In terms of installation and maintenance, the wireless electric pitch control system is easier to install, requiring no complicated wiring. When a fault occurs, troubleshooting and repair are easier due to the absence of a large number of cables, which can significantly reduce maintenance costs, reduce aircraft downtime, and improve operational efficiency.

[0004] Therefore, it is very meaningful to provide a frequency-hopping-based non-contact electric pitch control system for aircraft. Summary of the Invention

[0005] Therefore, the purpose of this invention is to provide a frequency-hopping-based non-contact electric pitch control system and method for aircraft propellers, so as to achieve non-contact control of aircraft propeller pitch.

[0006] The technical solution provided by the present invention is as follows: In the first aspect, the present invention provides a frequency-hopping-based non-contact electric pitch control system for aircraft, including a control end and a receiving end; the control end includes a battery, a microcontroller, a wireless frequency-hopping transmission module, and a transmitting antenna, the battery supplies power to the control end, the microcontroller is connected to the wireless frequency-hopping transmission module, and the wireless frequency-hopping transmission module is connected to the transmitting antenna;

[0007] The receiving end includes a variable pitch mechanism, a receiving antenna, a second wireless frequency hopping transmission module, a step-down voltage regulator module, a second battery, and a power wireless transmission module; the second battery supplies power to the receiving end through the power wireless transmission module and the step-down voltage regulator module.

[0008] Wireless frequency hopping transmission module one and wireless frequency hopping transmission module two have the same integrated structure, forming a half-duplex transmission module group with synchronous frequency hopping function.

[0009] Preferably, the wireless power transmission module includes a receiving coil and a transmitting coil, which together form a coupled coil group, both of which are wound in a circular coil manner.

[0010] Preferably, the integrated structure of the first wireless frequency hopping transmission module and the second wireless frequency hopping transmission module includes: a 485 interface circuit, a microcontroller minimum system circuit, a wireless radio frequency circuit, and a power supply circuit.

[0011] The present invention also provides a frequency-hopping-based non-contact electric pitch control method for aircraft, comprising: using a frequency-hopping signal transmission method to control the pitch control motor to rotate at a constant speed at a certain angle, thereby changing the pitch of the aircraft propeller.

[0012] Preferably, the microcontroller switches between different control types and sends different motor control data frames to the wireless frequency hopping transmission module 1;

[0013] The 485 interface circuit of the wireless frequency hopping transmission module converts the 485 signal into a high-frequency radio signal, and the transmitting antenna sends the high-frequency radio signal to the receiving end.

[0014] The receiving antenna receives high-frequency radio signals, which are then converted into 485 differential signals by the wireless frequency hopping transmission module 2 to control the long-distance wireless communication of the variable pitch motor; at the same time, the control end receives servo status data returned by the sensors in the variable pitch mechanism of the receiving end.

[0015] Preferably, in the wireless frequency hopping transmission module, after the active handshake party is powered on, it cyclically sends handshake frames at a preset fixed handshake transmission frequency. Then, the microcontroller configures the radio frequency chip to receive mode until it receives the handshake reception confirmation frame from the receiver, then stops sending, starts a timer interrupt, and performs frequency hopping at a certain time interval according to a preset frequency hopping sequence. The handshake success indicator light stays on.

[0016] After the passive handshake unit of the wireless frequency hopping transmission module is powered on, it cyclically scans for handshake frames at a preset fixed receiving frequency. Once a handshake frame is received, the loop ends, a handshake reception confirmation frame is sent, a timer interrupt is activated, and frequency hopping is performed at preset time intervals according to a pre-defined frequency hopping sequence. A handshake success indicator light remains constantly on. This completes the handshake and achieves synchronized frequency hopping.

[0017] This invention provides a frequency-hopping-based non-contact electric pitch control system and method for aircraft. It utilizes aircraft propeller pitch control to achieve wireless frequency-hopping electric control. The wireless frequency-hopping transmission section performs a synchronization frequency change based on timestamp values ​​after a handshake between the sender and receiver according to a preset frequency-hopping sequence. The frequency-hopping transmission module includes a function to automatically calibrate the local timestamp according to weights after receiving frames. The ground control terminal for wireless frequency-hopping electric pitch control uses the wireless frequency-hopping transmission module to convert the 485 signal and transmit it wirelessly over a long distance via an antenna. Upon receiving the signal, the receiver controls the pitch motor. The coupling coil group powers the receiver, and various motor data are fed back to the control terminal via sensors. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A block diagram of the overall structure of an aircraft electric pitch control system based on frequency hopping provided by the present invention;

[0021] Figure 2 This is a hardware connection diagram of the wireless frequency hopping transmission module provided by the present invention;

[0022] Figure 3 The schematic diagram of the 485 chip provided for this invention;

[0023] Figure 4 This is a schematic diagram of the radio frequency section of the wireless frequency hopping transmission module provided by the present invention.

[0024] Figure 5 The minimum system module circuit diagram of the wireless frequency hopping transmission module provided by the present invention;

[0025] Figure 6 Circuit diagram of the voltage regulator / boost module provided by this invention;

[0026] Figure 7 A wireless power supply transmission circuit diagram for the coil provided by the present invention;

[0027] Figure 8 A circuit diagram of a coil wireless power supply receiver provided for this invention. Detailed Implementation

[0028] The present invention will be further explained below with reference to specific implementation schemes, but this explanation does not limit the scope of the invention.

[0029] This invention discloses a frequency-hopping-based electric pitch control system for aircraft, comprising a battery 1, a microcontroller 2, a wireless frequency-hopping transmission module 3, a transmitting antenna 4, a receiving antenna 5, a wireless frequency-hopping transmission module 6, an electric servo motor 7, a servo motor driver 8, a sensor 9, a step-down voltage regulator module 10, a receiving coil 11, a transmitting coil 12, and a battery 13.

[0030] The control unit integrates a battery 1, a microcontroller 2, a wireless frequency hopping transmission module 3, and an antenna 4. The receiving unit integrates a receiving antenna 5, a wireless frequency hopping transmission module 6, an electric servo motor 7, a servo motor driver 8, a sensor 9, a step-down voltage regulator module 10, a receiving coil 11, a transmitting coil 12, and a battery 13. The control unit is powered by the battery 1, and the microcontroller 2 is connected to the wireless frequency hopping transmission module 3 via a 485 chip. The wireless frequency hopping transmission module 3 is connected to the transmitting antenna 4. Different control types are switched using the microcontroller's peripheral buttons, sending different motor control data frames to control the motors in communication with the aircraft propeller electric variable pitch system receiver. Simultaneously, the control unit receives data returned by sensors in the variable pitch mechanism of the receiver.

[0031] The receiving end consists of a receiving antenna 5 connected to a wireless frequency hopping transmission module 6, which in turn is connected to a variable pitch mechanism. A battery 13 is connected to a transmitting coil 12, which wirelessly transmits power to a receiving coil 11. The receiving coil 11, connected to a step-down voltage regulator module 10, then delivers stable power to the entire receiving end.

[0032] The pitch-changing mechanism is integrated with an electric servo motor 7, a servo motor driver 8, and sensors 9 for temperature, angle, etc., enabling functions such as driving, control, and feedback. The wireless frequency-hopping transmission module 3 and the wireless frequency-hopping transmission module 6 have the same hardware integration structure and adopt a half-duplex working mode, enabling synchronous frequency switching for data transmission.

[0033] To ensure interference resistance in signal transmission, all connections between communication devices, except for power lines, must use twisted-pair shielded cables. The twisting method ensures that the induced electromotive forces generated by external interference on the two conductors are equal in magnitude and opposite in direction, thus canceling each other out and suppressing interference. The outer shielding layer further blocks external electromagnetic signals from interfering with the internal transmitted signals, ensuring the integrity and accuracy of the signal during transmission.

[0034] The transmitting coil 6 and the receiving coil 7 form a coupled coil group, both of which are wound in a circular coil manner. The transmitting coil is powered by a rechargeable battery. The two coils are electromagnetically induced, and the receiving coil induces an electromotive force in the magnetic field, thereby generating current to realize wireless power transmission.

[0035] In the coupling coil group, the transmitting coil is in a fixed state, while the receiving coil and receiving antenna need to rotate at high speed along with the aircraft rotor and variable pitch motor. Under the condition of high speed rotation, the antenna and coil must be able to work stably and the power supply and signal transmission must not be significantly affected. Therefore, a shell made of high strength, lightweight material with good electromagnetic compatibility should be used to wrap the structure.

[0036] The control unit uses an STM32Z8T6 microcontroller as its main control chip. Different control types are switched via the microcontroller's peripheral buttons, sending different motor control data frames. After passing through an RS485 chip, the data frames are sent to a wireless frequency-hopping transmission module. This module has a RS485 interface circuit, which converts the RS485 signal into a high-frequency radio signal, which is then transmitted via a transmitting antenna. The receiving end has a receiving antenna to receive this high-frequency radio signal. The receiving end's wireless frequency-hopping transmission module then converts the high-frequency radio signal into a RS485 differential signal to control the variable-pitch motor, achieving long-distance wireless communication. Simultaneously, the control unit receives servo status data returned by sensors in the variable-pitch mechanism at the receiving end. To ensure the radio electromagnetic wave anti-interference capability of signal transmission, this invention includes a half-duplex wireless frequency hopping transmission system with a 485 interface, responsible for data interaction between the control end and the receiving end. Wireless frequency hopping transmission module 3 and wireless frequency hopping transmission module 6 form a half-duplex transmission module group with synchronous frequency hopping function. At the hardware level, the wireless frequency hopping transmission module integrates a 485 interface circuit, a microcontroller minimum system circuit, a wireless radio frequency circuit, and a power supply circuit. At the software code level, one is the active sender of handshake frames, and the other is the passive receiver of handshake frames. After a successful handshake, the frequency hopping time start is synchronized. It has a dynamic time synchronization calibration function.

[0037] The aforementioned wireless frequency hopping transmission module 3.6 for both the transmitting and receiving ends has the same hardware structure, differing only in software code between the active and passive handshake parties. After power-on, the active handshake party actively sends handshake frames cyclically at a preset fixed handshake transmission frequency. After transmission, the microcontroller configures the RF chip to receive mode until it receives a handshake reception confirmation frame from the receiver. Upon receiving this frame, it stops transmitting, starts a timer interrupt, and performs frequency hopping at preset time intervals according to a pre-defined frequency hopping sequence. A handshake success indicator light remains constantly on. Similarly, after power-on, the passive handshake party cyclically scans for received handshake frames at a preset fixed receiving frequency. Upon receiving a handshake frame, it exits the loop, sends a handshake reception confirmation frame, starts a timer interrupt, and performs frequency hopping at preset time intervals according to a pre-defined frequency hopping sequence. A handshake success indicator light remains constantly on. This completes the handshake and achieves synchronized frequency hopping.

[0038] The wireless frequency hopping transmission module uses the MAX3485 chip as the interface circuit, serving as the data interaction interface for the pitch mechanism or ground control terminal. It uses the NRF24L01 chip as the radio frequency chip, which supports up to 125 frequency points with a channel spacing of 1MHz. Utilizing the chip's electrical characteristics, the microcontroller modifies the values ​​of its configuration registers, thereby changing its communication operating frequency.

[0039] In addition, the present invention also provides a method for an aircraft electric variable pitch control system based on frequency hopping. The main principle is to control the variable pitch motor to rotate at a constant speed and change the pitch of the aircraft propeller by transmitting signals in a frequency hopping manner.

[0040] After a successful handshake, the module enters a working scanning loop. The wireless frequency hopping transmission module first checks for data frames from the 485 interface. If present, the microcontroller encapsulates the data frame according to a specific communication protocol. The encapsulated data frame includes the sender's local timestamp, data type information, and the data itself. This encapsulated data frame is then transmitted via the antenna. The module immediately switches to receive mode, waiting for an ACK from the receiver. If no ACK is received, it switches back to transmit mode and retransmits. If an ACK is received, the current transmission loop ends, and the module returns to the working scanning loop. If no ACK is received after exceeding the transmission limit, the current process ends, and the module returns to the working scanning loop. If there are no data frames on the 485 interface, a wireless receive scan is performed. If no data is found, the process of scanning the 485 interface and then scanning the wireless receive scan is repeated. If data is found, the data frame is parsed, and the data portion is forwarded to the 485 interface for transmission. This achieves half-duplex operation.

[0041] The data frame parsing function of the wireless transmission module parses out the timestamp information of the sender. The timestamp information is used as the basis for judging the timer interrupt. The microcontroller calibrates the local timestamp according to a certain weight, thereby realizing the dynamic time synchronization calibration function.

[0042] The variable-pitch motor is powered by a coupling coil assembly, which consists of circular coils. A rechargeable battery powers the transmitting coil. The transmitting and receiving coils, through electromagnetic induction, induce an electromotive force in a magnetic field, generating a current that transmits electrical energy to the variable-pitch motor, achieving wireless power transmission. Since the electromagnetic induction effect is significantly affected by factors such as the size and distance between the two coils, the coupling effect can vary under different environments. Therefore, a stabilizing circuit must be included in the wireless variable-pitch receiver to prevent damage to the wireless transmission module and the variable-pitch motor due to excessive coupling current. The transmitting coil in the coupling coil assembly is fixed, while the receiving coil and antenna rotate at high speed along with the aircraft rotor and variable-pitch motor. To ensure stable operation of the antenna and coils during high-speed rotation without significant impact on power supply and signal transmission, a high-strength, lightweight shell with good electromagnetic compatibility should be used to encase this structure.

[0043] The variable pitch motor is equipped with various sensors such as temperature and angle, and supports the main control panel to query the motor's real-time status. During operation, every time the main control panel sends a control command, the variable pitch motor can return its angle, voltage, power and other data to the transmitter through the drive response. After receiving the data, the main control panel displays it on its LCD screen so that the operator can understand the motor status.

[0044] To ensure interference resistance in signal transmission, all connections between communication devices, except for power lines, must use twisted-pair shielded cables. The twisting method ensures that the induced electromotive forces generated by external interference on the two conductors are equal in magnitude and opposite in direction, thus canceling each other out and suppressing interference. The outer shielding layer further blocks external electromagnetic signals from interfering with the internal transmitted signals, ensuring the integrity and accuracy of the signal during transmission.

[0045] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0046] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A frequency-hopping-based non-contact electric pitch control system for aircraft, characterized in that, It includes a control terminal and a receiving terminal; the control terminal includes a battery (1), a microcontroller (2), a wireless frequency hopping transmission module (3) and a transmitting antenna (4). The battery (1) powers the control terminal. The microcontroller (2) is connected to the wireless frequency hopping transmission module (3). The wireless frequency hopping transmission module (3) is connected to the transmitting antenna (4). The receiving end includes a variable pitch mechanism, a receiving antenna (5), a second wireless frequency hopping transmission module (6), a step-down voltage regulator module (10), a second battery (13), and a power wireless transmission module; the second battery (13) supplies power to the receiving end through the power wireless transmission module and the step-down voltage regulator module (10); The wireless frequency hopping transmission module 1 (3) and the wireless frequency hopping transmission module 2 (6) have the same integrated structure, forming a half-duplex transmission module group with synchronous frequency hopping function.

2. The frequency-hopping-based non-contact electric pitch control system for aircraft according to claim 1, characterized in that, The wireless power transmission module includes a receiving coil (11) and a transmitting coil (12). The receiving coil (11) and the transmitting coil (12) form a coupling coil group, which are all wound in a circular coil manner.

3. The frequency-hopping-based non-contact electric pitch control system for aircraft according to claim 1, characterized in that, The integrated structure of the wireless frequency hopping transmission module one (3) and the wireless frequency hopping transmission module two (6) includes: a 485 interface circuit, a microcontroller minimum system circuit, a wireless radio frequency circuit, and a power supply circuit.

4. A frequency-hopping-based non-contact electric pitch control method for aircraft, characterized in that, include: The variable pitch motor is controlled to rotate at a constant speed and a certain angle by using frequency hopping transmission signal method, thereby changing the pitch of the aircraft propeller.

5. The frequency-hopping-based non-contact electric pitch control method for aircraft according to claim 4, characterized in that, The microcontroller switches between different control types and sends different motor control data frames to the wireless frequency hopping transmission module (3). The 485 interface circuit of the wireless frequency hopping transmission module (3) converts the 485 signal into a high-frequency radio signal, and the transmitting antenna sends the high-frequency radio signal to the receiving end. The receiving antenna receives high-frequency radio signals, and the wireless frequency hopping transmission module 2 (6) converts the high-frequency radio signals into 485 differential signals to control the long-distance wireless communication of the variable pitch motor; at the same time, the control end receives the servo status data returned by the sensor in the variable pitch mechanism of the receiving end.

6. The frequency-hopping-based non-contact electric pitch control method for aircraft according to claim 4, characterized in that, After the active handshake party in the wireless frequency hopping transmission module (3) is powered on, it sends handshake frames in a loop at a preset fixed handshake transmission frequency. Then, the microcontroller configures the radio frequency chip to receive mode until it receives the handshake reception confirmation frame from the receiver and stops sending. The timer interrupt is enabled, and frequency hopping is performed at a certain time interval according to the preset frequency hopping sequence. The handshake success indicator light is always on. After the passive handshake unit of the wireless frequency hopping transmission module 2 (6) is powered on, it scans cyclically at a preset fixed receiving frequency to see if a handshake frame is received. Once a handshake frame is received, it exits the loop, sends a handshake reception confirmation frame, enables a timer interrupt, and performs frequency hopping at certain time intervals according to a preset frequency hopping sequence. The handshake success indicator light remains on. This completes the handshake and achieves synchronous frequency hopping.

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