A phase control method for a compound wing eVTOL multicopter

Abstract

The application discloses a phase control method for a composite wing eVTOL multi-rotor, the multi-rotor is a six-rotor structure, the six rotors are arranged in two rows, a first row includes a first rotor, a second rotor and a third rotor, and a second row includes a fourth rotor, a fifth rotor and a sixth rotor. It is aimed at the special structure of the six-rotor of the composite wing eVTOL configuration, realizes the accurate control of the fixed phase difference of 90 degrees between adjacent rotors, monitors the phase state in real time and calibrates, adapts to the initialization, vertical take-off, transition and cruising of the ground in each flight stage, reduces the airflow interference between the rotors, reduces the interference noise between the rotors, improves the flight stability, is suitable for other multi-rotor structures and enhances the universality.

Description

Technical Field

[0001] This invention relates to the field of multi-rotor aircraft control technology, specifically to a phase control method for a compound wing eVTOL multi-rotor. Background Technology

[0002] eVTOL (Electric Vertical Take-Off and Landing) aircraft, as a new type of aircraft, combines the advantages of helicopter vertical take-off and landing with the high-speed cruise of fixed-wing aircraft, and has broad application prospects in urban commuting, emergency rescue, logistics transportation and other fields. Multi-rotor structures are the core power source for the vertical take-off phase of compound-wing eVTOLs. Among them, the six-rotor structure is widely used in mainstream eVTOL models such as VoloRegion due to its high power redundancy and good flight stability.

[0003] In existing technologies, eVTOL rotor control primarily focuses on speed regulation to achieve attitude control and lift adjustment, but neglects phase coordination control between rotors. Since adjacent rotors in a six-rotor system typically rotate in opposite directions, if the phase of adjacent rotors is not fixed, the rotor blades may rotate synchronously at the same speed. This leads to strong airflow interference between adjacent rotors, causing airflow vortices, increased aerodynamic noise, and other problems. Consequently, it affects the aircraft's flight stability and causes significant noise interference, especially during takeoff and landing and transition phases. This interference can significantly reduce the aircraft's attitude control accuracy and greatly decrease community acceptance, potentially even posing flight safety hazards.

[0004] Furthermore, existing multi-rotor phase control methods are mostly designed for closely spaced six-rotor aircraft, failing to consider the special structure of compound wing eVTOL models such as VoloRegion, where six-rotor (multi-rotor) aircraft are divided into two rows (multiple even-numbered rows) and arranged accordingly. This makes them unsuitable for the phase control requirements of such models. At the same time, existing methods do not incorporate motor pole pair parameters for angle calibration, resulting in insufficient phase detection accuracy and an inability to accurately maintain the phase difference. Moreover, during the cruise phase, phase locking is not performed after the rotors stop working, and the rotor blades are prone to rotation due to airflow disturbances, affecting the aerodynamic shape of the aircraft and increasing cruise drag.

[0005] Therefore, for the special arrangement structure of the compound wing eVTOL configuration six-rotor, designing a phase control method that can achieve a fixed 90-degree phase difference between adjacent rotors, real-time monitoring and calibration, and adapt to each flight stage has become the key to solving the above technical problems. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a phase control method for a compound wing eVTOL multi-rotor. It is designed for the special structure of a six-rotor compound wing eVTOL configuration (two rows arranged in opposite directions), and achieves precise control of a fixed 90-degree phase difference between adjacent rotors. It monitors and calibrates the phase status in real time, adapts to various flight stages such as ground initialization, vertical takeoff, transition, and cruise, reduces airflow interference between rotors, lowers interference noise between rotors, and improves flight stability. At the same time, it is compatible with other multi-rotor structures, enhancing versatility.

[0007] The solution of the present invention to the aforementioned technical problem is:

[0008] A phase control method for a compound-wing eVTOL multi-rotor, wherein the multi-rotor is a six-rotor structure arranged in two rows. The first row includes rotors 1, 2, and 3 (arranged sequentially from front to back), and the second row includes rotors 4, 5, and 6 (arranged sequentially from front to back). Rotors 1 and 4 are positioned at the front of the eVTOL, rotors 2 and 5 are positioned in the middle of the eVTOL, and rotors 3 and 6 are positioned at the rear of the eVTOL. Rotors 1 and 4 are in phase but rotate in opposite directions; rotors 2 and 5 are in phase but rotate in opposite directions; rotors 3 and 6 are in phase but rotate in opposite directions; and adjacent rotors (rotors 1 and 2, 2 and 3, 4 and 5, 5 and 6) rotate in opposite directions. The control method includes the following steps:

[0009] S1. Set phase control reference: With the forward direction of eVTOL as the 0-degree reference line, define one blade of each two-bladed rotor as the reference blade, and set the initial reference angle to the 12 o'clock direction (i.e., the direction perpendicular to the 0-degree reference line).

[0010] The definitions of each parameter need to be clarified here:

[0011] - eVTOL forward direction 0-degree reference line: This is the forward direction of the aircraft during normal flight. It serves as a reference for all phase angles and can be located by the aircraft's heading sensor. The positioning accuracy is ≤0.5 degrees, ensuring the accuracy of the phase reference.

[0012] - Reference blade: For each dual-bladed rotor, one blade is selected as the reference object for phase detection and control. It is preferable to select the starting blade in the rotor rotation direction (e.g., for a clockwise rotating rotor, select the blade with the initial position at the 12 o'clock position as the reference blade). The selection of the reference blade must be calibrated before the aircraft leaves the factory and remain fixed after calibration to avoid phase control deviation due to the replacement of the reference blade.

[0013] - Initial reference angle 12 o'clock direction: that is, the direction that is perpendicular to the 0-degree reference line of the eVTOL forward direction and upward, corresponding to a mechanical angle of 90 degrees (with the 0-degree reference line as horizontal forward and clockwise as the direction of angle increase). This initial angle is the reference position for phase initialization, ensuring that the initial phase reference of all rotors is consistent.

[0014] S2. Ground Initialization Phase Calibration: When the eVTOL is not in flight and is stationary on the ground, the phase control algorithm is activated to initialize the phase of the six rotors, so that a fixed phase difference of 90 degrees is formed between the reference blades of adjacent rotors (rotor 1 and rotor 2, rotor 2 and rotor 3, rotor 4 and rotor 5, rotor 5 and rotor 6). That is, if the reference blade of the preceding rotor is at the 12 o'clock position, the reference blade of the adjacent following rotor is at the 3 o'clock position.

[0015] The specific initialization process and parameter explanations are as follows:

[0016] S21. Stationary State Detection: The attitude sensor and wheel-mounted sensor of eVTOL are used to detect whether the aircraft is stationary on the ground. The criteria for judging the stationary state are: the attitude angle deviation of the aircraft is ≤ ±1 degree, the pressure value of the wheel-mounted sensor is ≥ the preset threshold (the preset threshold is 80% of the empty weight of the aircraft to ensure that the aircraft has not left the ground), and the duration is ≥ 1 second; if it is not stationary, the initialization program is paused until the stationary conditions are met.

[0017] S22. Reference Blade Initial Position Calibration: Control the six-rotor motor to idle (speed ≤ 50 rpm to avoid danger caused by high-speed rotor rotation), collect the real-time position of each rotor reference blade through the motor encoder, if the reference blade is not in the 12 o'clock position (deviation > ±1 degree), output the control signal through the motor drive module to adjust the motor rotation angle, and accurately adjust the reference blade to the 12 o'clock position with an adjustment accuracy ≤ ±0.5 degrees; after the adjustment is completed, control the motor to stop rotating, and keep the reference blade position unchanged.

[0018] S23. Setting the phase difference between adjacent rotors: Taking rotor 1 as the reference (reference blade at the 12 o'clock position), control the reference blade of rotor 2 (adjacent to rotor 1, rotating in the opposite direction) to rotate to the 3 o'clock position, forming a 90-degree mechanical phase difference; where, if rotor 1 rotates clockwise, rotor 2 rotates counterclockwise, and the reference blade rotates to the 3 o'clock position (90 degrees clockwise rotation); if rotor 1 rotates counterclockwise, rotor 2 rotates clockwise, and the reference blade rotates to the 9 o'clock position (90 degrees counterclockwise rotation), ensuring that adjacent rotor blades rotating in opposite directions are misaligned, reducing airflow interference; after the phase difference is adjusted, detect the mechanical angle difference between the reference blades of rotor 1 and rotor 2. If the deviation is > ±1 degree, readjust until the requirements are met.

[0019] S24. Subsequent adjacent rotor phase adjustment: Using rotor No. 2 as the reference, control the reference blade of rotor No. 3 (adjacent to rotor No. 2, rotating in the opposite direction) to a position with a 90-degree phase difference from the reference blade of rotor No. 2. The adjustment logic is the same as in step S23, ensuring that the phase difference between rotor No. 2 and rotor No. 3 is 90 degrees. Similarly, using rotor No. 4 as the reference, control rotor No. 5, and using rotor No. 5 as the reference, control rotor No. 6, ensuring that the phase difference between rotor No. 4 and rotor No. 5, and between rotor No. 5 and rotor No. 6, is 90 degrees.

[0020] S25. Corresponding rotor phase synchronization: Control the reference blade of rotor 4 (corresponding to rotor 1) to maintain the same phase as rotor 1 (12 o'clock direction), and simultaneously activate the reverse rotation mode of rotor 4 (opposite to the rotation direction of rotor 1); Control the reference blade of rotor 5 (corresponding to rotor 2) to maintain the same phase as rotor 2, and activate the reverse rotation mode of rotor 5 (opposite to the rotation direction of rotor 2); Control the reference blade of rotor 6 (corresponding to rotor 3) to maintain the same phase as rotor 3, and activate the reverse rotation mode of rotor 6 (opposite to the rotation direction of rotor 3); The phase synchronization accuracy of the corresponding rotors is ≤ ±0.5 degrees, ensuring that the phases of the two rotor rows are synchronized.

[0021] S26. Initialization Verification: After initialization, start the phase detection module to collect the phase signal of each rotor at a sampling frequency of 100Hz, and detect whether the phase difference between adjacent rotors (rotor 1-rotor 2, rotor 2-rotor 3, rotor 4-rotor 5, rotor 5-rotor 6) is 90 degrees ± 1 degree, and whether the phases of the corresponding rotors (rotor 1-rotor 4, rotor 2-rotor 5, rotor 3-rotor 6) are the same (deviation ≤ ± 0.5 degrees); if there is a deviation, repeat steps S22-S25 until all phase parameters meet the preset requirements; after the verification is passed, the phase initialization is completed and the system enters the takeoff-ready state.

[0022] S3. Phase maintenance during vertical take-off and transition phase: After the eVTOL starts the vertical take-off program, it monitors the rotational speed and phase of each rotor in real time. When the rotational speed of each rotor reaches the preset stable value and maintains the same rotational speed, the phase of each rotor is adjusted in real time through the phase control algorithm to ensure that the 90-degree phase difference between adjacent rotors is always maintained, while maintaining the same phase of the corresponding rotors (rotor 1 and rotor 4, rotor 2 and rotor 5, rotor 3 and rotor 6).

[0023] The relevant parameters and control logic for this step are explained in detail below:

[0024] - Vertical take-off procedure start conditions: After the pilot issues the vertical take-off command, the system detects that the battery voltage is ≥ the preset threshold, there is no fault signal in the motor, and the phase initialization completion signal is valid, then the vertical take-off procedure can be started; During the vertical take-off phase, the speed of each rotor gradually increases from idle speed to the preset vertical take-off speed (usually 1500-2000 rpm), with an increase rate of 50-100 rpm / s, to avoid sudden changes in speed that may cause phase deviation.

[0025] - Rotor speed stability judgment criteria: The absolute value of the deviation between the real-time rotational speed of each rotor and the preset target rotational speed (the target rotational speed during the vertical take-off phase is 1500-2000 rpm, and the target rotational speed during the transition phase is dynamically adjusted according to the flight attitude, with a range of 1000-2000 rpm) is ≤ ±10 rpm, and the duration of this deviation is ≥ 0.5s; when the rotational speed deviation exceeds this range, the phase maintenance program is paused, and the rotational speed of each rotor is adjusted to a stable state first through the rotational speed control algorithm before the phase maintenance is restored, so as to avoid phase difference loss of control due to rotational speed fluctuations.

[0026] - Real-time phase maintenance logic: The phase control algorithm adopts a PID control strategy, with the 90-degree phase difference between adjacent rotors as the target value and the real-time acquired phase difference as the feedback value. The control signal is output to each rotor motor drive module to adjust the rotation angle of the motor and realize closed-loop control of the phase difference. The PID control parameters are adjusted to ensure the response speed and stability of phase adjustment and avoid phase oscillation.

[0027] - Corresponding rotor phase synchronization maintenance: During the phase maintenance process, the phase signals of rotor 1 and rotor 4, rotor 2 and rotor 5, and rotor 3 and rotor 6 are compared in real time. If the phase deviation is > ±0.5 degrees, the phase of the corresponding rotor is adjusted immediately to ensure phase coordination between the two rows of rotors and avoid imbalance of lift between the left and right sides of the aircraft due to phase deviation of the corresponding rotor.

[0028] S4. Cruise Phase Phase Lock: When the eVTOL enters the cruise phase, the six rotors stop working, and the reference blades of all rotors are fixed at 0 degrees (in the same direction as the eVTOL's forward direction) until the cruise phase ends and the system re-enters the vertical take-off or transition phase.

[0029] The relevant parameters and control logic for this step are explained in detail below:

[0030] - Cruise phase judgment criteria: The eVTOL's flight speed reaches the preset cruise speed (usually ≥120km / h), and the power output of the fixed wing and the thrust ducted fan reaches the preset stable value (fixed wing lift ≥80% of the total weight of the aircraft, thrust ducted fan thrust ≥110% of the flight drag of the aircraft), and the duration is ≥1s; at this time, the system determines that it has entered the cruise phase and issues a six-rotor stop working command.

[0031] - Rotor Stop Operation: Upon receiving the stop command, control each rotor motor to gradually reduce its speed at a rate of 100-150 rpm / s until the speed drops to 0 rpm. After the motors stop rotating, activate the mechanical locking mechanism (such as an electromagnetic lock) to lock each rotor blade in the 0-degree direction (consistent with the eVTOL forward direction). The locking accuracy is ≤ ±1 degree to prevent the rotor from rotating due to airflow disturbances, ensuring a smooth aerodynamic shape during the aircraft's cruise phase and reducing cruise drag.

[0032] - Cruise phase phase unlocking conditions: When the pilot issues a command to leave the cruise phase (such as needing to land or adjust flight attitude), the system detects that the flight speed has dropped below the cruise speed (<60km / h) and the power output of the fixed wing and thrust ducted fan has dropped below the preset threshold. The mechanical locking mechanism is immediately unlocked and the phase initialization procedure is initiated to prepare for the subsequent vertical takeoff or transition phase.

[0033] S5. Real-time phase monitoring and calibration: Throughout the entire phase control process (except for the cruise phase), the motor speed signal and phase signal of each rotor are collected in real time. Angle calibration is performed in combination with the number of motor pole pairs. The calculation formula is: actual phase angle = collected motor electrical angle ÷ number of motor pole pairs. This ensures that the collected phase signal accurately reflects the actual phase state of the rotor. When the same speed is detected but the phase difference deviates from the preset value of 90 degrees, the phase adjustment program is immediately started to correct the phase difference to the preset range.

[0034] The relevant parameters and calibration logic for this step are explained in detail below:

[0035] - Signal acquisition module: The speed signal is acquired through the motor encoder at a frequency of 200Hz and an acquisition accuracy of ≤1rpm; the phase signal is acquired through the motor's built-in Hall sensor or encoder at a frequency of 100Hz-200Hz and an acquisition accuracy of ≤0.1 degrees; the acquired signals are filtered (using Kalman filtering algorithm with a filtering coefficient of 0.05-0.1) to eliminate noise interference and ensure signal accuracy.

[0036] - Motor pole pair parameter description: The number of motor pole pairs N is a positive integer, and the specific number is determined according to the motor model used in eVTOL; the conversion relationship between motor electrical angle and mechanical angle is: electrical angle = mechanical angle × N. Therefore, the actual phase angle (mechanical angle) = the collected motor electrical angle ÷ N. This formula can be used to convert the collected electrical angle into the actual mechanical phase angle of the rotor, avoiding phase detection deviation caused by the number of motor pole pairs.

[0037] - Phase calibration frequency: Phase calibration is performed every 10ms. That is, based on the collected electrical angle and the number of motor pole pairs, the actual phase angle is calculated and compared with the preset phase value (90-degree phase difference between adjacent rotors, the same phase of corresponding rotors). If there is a deviation, the phase adjustment program is started immediately.

[0038] - Phase Deviation Correction Logic: When the rotation speed is the same (deviation ≤ ±10 rpm) but the phase difference between adjacent rotors deviates from 90 degrees ± 5 degrees, the phase adjustment program is started. According to the direction and magnitude of the deviation, the corresponding control signal is output to adjust the motor rotation angle and correct the phase difference. The adjustment response time is ≤ 0.1s and the adjustment accuracy is ≤ ±1 degree, ensuring that the phase difference is quickly restored to the preset range. If the phase deviation continues to exceed ±10 degrees and the duration is ≥ 0.3s, the system issues a fault alarm signal and reduces the rotor speed to ensure flight safety.

[0039] Furthermore, the control method of the present invention can be adapted to other multi-rotor structures (such as quadcopters, octagonals, twelve-rotors, sixteen-rotors, etc.). When adapting, the phase difference setting of adjacent rotors (maintaining the core requirement of 90 degrees) and the phase synchronization rules of the corresponding rotors are adjusted according to the number and arrangement of the multi-rotor to achieve the same phase control effect, which has strong versatility.

[0040] The outstanding effects of this invention are:

[0041] (1) Special arrangement structure for the compound airfoil eVTOL configuration adapted to six rotors: In view of the characteristics of the six rotors being divided into two rows and correspondingly arranged (rotor 1 and rotor 4, rotor 2 and rotor 5, rotor 3 and rotor 6 correspond to each other, and adjacent rotors rotate in opposite directions), a corresponding phase control logic was designed to ensure that the corresponding rotors have the same phase and the phase difference between adjacent rotors is 90 degrees, which perfectly adapts to the structural requirements of the model and solves the problem that the existing methods cannot adapt to this kind of special arrangement.

[0042] (2) Improve flight stability and reduce airflow interference: By fixing the 90-degree phase difference between adjacent rotors, the rotor blades at the same rotation speed are precisely misaligned, avoiding airflow interference caused by synchronous blade rotation, reducing aerodynamic noise and airflow vortices, significantly improving flight stability during the eVTOL vertical take-off and transition phases, and improving attitude control accuracy. At the same time, the opposing rotation of adjacent rotors can cancel out some of the torque, and compared with rotation in the same direction, it can significantly reduce the interference noise between rotors.

[0043] (3) High phase control accuracy: Angle calibration is performed by combining the number of motor pole pairs. The motor electrical angle is converted into the actual mechanical phase angle of the rotor by formula, eliminating the detection deviation caused by the motor pole pairs. At the same time, PID control strategy and high-frequency signal acquisition are adopted to ensure the control accuracy and stability of phase difference. The phase adjustment response is fast and the deviation is small.

[0044] (4) Adaptation to all flight phases: Corresponding phase control strategies were designed for the characteristics of each phase, including ground initialization, vertical takeoff, transition, and cruise. Ground initialization ensures accurate phase reference, vertical takeoff and transition phases maintain phase difference, and cruise phase locks phase, achieving precise phase control throughout the entire phase and improving the overall flight performance of the aircraft.

[0045] (5) High versatility: It is not only applicable to six-rotor structures, but also adaptable to other multi-rotor structures. The same control effect can be achieved simply by adjusting the phase control rules according to the number and arrangement of rotors. It has a wide range of applications. Attached Figure Description

[0046] Figure 1 A top view of the composite wing eVTOL structure and phase arrangement;

[0047] Figure 2 Here is a flowchart of the overall phase control method;

[0048] Figure 3 A detailed flowchart for initializing phase calibration on the ground;

[0049] Figure 4 This is a schematic diagram illustrating the principle of real-time phase monitoring and calibration. Detailed Implementation

[0050] For example, see below. Figures 1 to 4 As shown, this embodiment takes a six-rotor compound wing eVTOL configuration as an example. The six rotors are arranged in two rows. The first row (left row) includes rotor 1, rotor 2, and rotor 3 (arranged from front to back). The second row (right row) includes rotor 4, rotor 5, and rotor 6 (arranged from front to back). Rotor 1 and rotor 4 are arranged at the front of the eVTOL, rotor 2 and rotor 5 are arranged in the middle, and rotor 3 and rotor 6 are arranged at the rear. Rotor 1, rotor 3, and rotor 5 all rotate clockwise, while rotor 2, rotor 4, and rotor 6 all rotate counterclockwise (opposite to the rotation direction of the corresponding rotors). The number of motor pole pairs N=2, the preset vertical take-off speed is 1800 rpm, the cruising speed is 80 km / h, and the phase detection sampling frequency is 150 Hz.

[0051] The specific steps of the phase control method in this embodiment are as follows:

[0052] S1. Set phase control reference: With the forward direction of eVTOL as the 0-degree reference line (horizontally forward), define the left blade of each two-bladed rotor as the reference blade, and set the initial reference angle to the 12 o'clock direction (vertically upward with the 0-degree reference line, and the mechanical angle is 90 degrees).

[0053] S2. Ground initialization phase calibration:

[0054] S21. Detect whether the eVTOL is stationary on the ground. The attitude angle deviation is detected by the attitude sensor as 0.3 degrees, and the pressure value of the wheel-mounted sensor is 90% of the empty weight of the aircraft for 1.5 seconds. If the stationary condition is met, start the initialization program.

[0055] S22. Control the idle speed of each rotor motor (40 rpm), collect the position of each reference blade through the encoder, find that the reference blade of rotor No. 3 is 2 degrees off from the 12 o'clock position, adjust it precisely to the 12 o'clock position through motor drive, with an adjustment accuracy of 0.3 degrees; after all rotor reference blades are adjusted, control the motor to stop rotating.

[0056] S23. Using rotor 1 (clockwise rotation) as a reference (reference blade at 12 o'clock direction), control the reference blade of rotor 2 (counterclockwise rotation) to rotate 90 degrees clockwise to the 3 o'clock direction (mechanical angle 180 degrees). Detect that the phase difference between rotor 1 and rotor 2 is 90 degrees, with a deviation of 0.2 degrees, which meets the requirements.

[0057] S24. Using rotor 2 (rotating counterclockwise) as a reference, control the reference blade of rotor 3 (rotating clockwise) to rotate 90 degrees clockwise to the 6 o'clock position (mechanical angle 270 degrees), with a phase difference of 90 degrees and a deviation of 0.1 degrees; using rotor 4 (rotating counterclockwise) as a reference, control the reference blade of rotor 5 (rotating clockwise) to the 3 o'clock position, and the reference blade of rotor 6 (rotating counterclockwise) to the 6 o'clock position, ensuring that the phase difference between rotor 4 and rotor 5, and between rotor 5 and rotor 6, is 90 degrees.

[0058] S25. Control rotor 4 (rotating counterclockwise) to keep the reference blade at the 12 o'clock position (same as rotor 1), rotor 5 (rotating clockwise) to keep the reference blade at the 3 o'clock position (same as rotor 2), and rotor 6 (rotating counterclockwise) to keep the reference blade at the 6 o'clock position (same as rotor 3). The phase deviation of the corresponding rotors is 0.2 degrees, which meets the synchronization requirements.

[0059] S26. Collect the phase signal of each rotor at a sampling frequency of 150Hz. The phase difference between adjacent rotors is detected to be 90 degrees ± 0.3 degrees. The corresponding rotor phase deviation is ≤ 0.2 degrees. The initialization verification is passed and the aircraft enters the takeoff-ready state.

[0060] S3. Phase maintenance during the vertical rise and transition phases:

[0061] Initiate the vertical lift program, increasing the speed of each rotor from 40 rpm to 1800 rpm at a rate of 80 rpm / s. During the increase, adjust the speed in real time to ensure that the speed deviation is ≤ ±10 rpm. When the speed stabilizes at 1800 rpm for 0.6 seconds, initiate the phase maintenance program.

[0062] The system uses a PID control strategy to collect phase signals from each rotor in real time and calculates the actual phase angle (collected electrical angle ÷ 2). When the phase difference between rotor 2 (counterclockwise) and rotor 3 (clockwise) deviates from 90 degrees by 3 degrees, a control signal is output to adjust the rotation angle of the motor of rotor 3. After 0.08 seconds, the phase difference returns to 90 degrees, with an adjustment accuracy of 0.5 degrees. At the same time, the system compares the phases of rotors 1 (clockwise) and 4 (counterclockwise), 2 (counterclockwise) and 5 (clockwise), and 3 (clockwise) and 6 (counterclockwise) in real time to ensure that the corresponding rotor phases are synchronized with a deviation of ≤0.3 degrees.

[0063] During the transition phase, the target rotation speed is adjusted to 1500 rpm based on the flight attitude. After the rotation speed stabilizes, the 90-degree phase difference between adjacent rotors is maintained to ensure flight stability during the transition phase.

[0064] S4. Phase lock during cruise phase:

[0065] When the eVTOL reaches a flight speed of 80 km / h, the fixed-wing lift reaches 85% of the total weight of the aircraft, and the ducted fan thrust reaches 115% of the flight drag, and this lasts for 1.2 seconds, it is determined that the aircraft has entered the cruise phase. The system then controls each rotor motor to decelerate to 0 rpm at a rate of 120 rpm / s, activates the electromagnetic lock, and locks all rotor reference blades in the 0-degree direction (consistent with the forward direction) with a locking accuracy of 0.8 degrees.

[0066] S5. Real-time phase monitoring and calibration:

[0067] During the ground initialization, vertical take-off, and transition phases, rotational speed and phase signals were acquired at a frequency of 150Hz. After Kalman filtering, the actual phase angle was calculated using N=2. Calibration was performed every 10ms. When it was detected that the rotational speeds of rotor 1 (clockwise) and rotor 2 (counterclockwise) were the same (1800rpm) but the phase difference deviated by 90 degrees by 6 degrees, the adjustment program was immediately initiated. After 0.09s, the phase difference was corrected to 90 degrees ± 0.4 degrees. No phase deviation exceeding the standard occurred during the entire process, and the phase control was stable and reliable.

[0068] When it is necessary to disengage from the cruise phase, the flight speed is reduced to 55 km / h, the power output of the fixed wing and the thrust ducted fan is reduced to below the preset threshold, the electromagnetic lock is unlocked, the phase initialization program is restarted, and preparations are made for subsequent vertical takeoff.

[0069] In this embodiment, through the above control method, the phase difference between adjacent rotors of the six-rotor is always maintained within the range of 90 degrees ± 1 degree, corresponding to a rotor phase synchronization accuracy of ≤ 0.5 degrees. The airflow interference during vertical take-off and transition is significantly reduced, the flight attitude is stable, and the rotor locking is reliable during the cruise phase, fully meeting the control requirements of the six-rotor compound wing eVTOL configuration.

[0070] Finally, the above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention, and the patent protection scope of the present invention should be defined by the claims.

Claims

1. A phase control method for a compound wing eVTOL multirotor, characterized in that, The multi-rotor has a six-rotor structure, which is arranged symmetrically in two rows. The first row includes rotor 1 (1), rotor 2 (2), and rotor 3 (3) arranged from front to back. The second row includes rotor 4 (4), rotor 5 (5), and rotor 6 (6) arranged from front to back. Rotor 1 (1) and rotor 4 (4) are arranged at the front of the electric vertical take-off and landing aircraft, and rotor 2 (2) and rotor 5 (5) are arranged at the front of the aircraft. In the middle of the electric vertical takeoff and landing (EVTOL) aircraft, rotors 3 (3) and 6 (6) are arranged correspondingly at the tail of the EVTOL aircraft; rotors 1 (1) and 4 (4) are in the same phase but rotate in opposite directions, rotors 2 (2) and 5 (5) are in the same phase but rotate in opposite directions, rotors 3 (3) and 6 (6) are in the same phase but rotate in opposite directions, and adjacent rotors in the same column rotate in opposite directions; the control method includes the following steps: S1. Set phase control reference: Take the forward direction of the electric vertical take-off and landing aircraft as the 0-degree reference line, define one blade of each two-bladed rotor as the reference blade, and set the initial reference angle to the 12 o'clock direction. S2. Ground initialization phase calibration: When the electric vertical take-off and landing aircraft is not in take-off and is stationary on the ground, the phase control algorithm is activated to initialize the phase of the six rotors, so that a fixed mechanical phase difference of 90 degrees is formed between the reference blades of adjacent rotors in the same column. That is, if the reference blade of the previous rotor is in the 12 o'clock direction, the reference blade of the adjacent next rotor is in the 3 o'clock direction, while ensuring that the reference blades of the corresponding rotors in the two columns are completely identical. S3. Phase maintenance during vertical take-off and transition phase: After the electric vertical take-off and landing aircraft starts the vertical take-off procedure, the rotational speed and phase of each rotor are monitored in real time. When the rotational speed of each rotor reaches the preset stable value and maintains the same rotational speed, the phase of each rotor is adjusted in real time through the phase control algorithm to ensure that the 90-degree fixed mechanical phase difference between adjacent rotors in the same row is always maintained, and at the same time, the phases of the corresponding rotors in the two rows are the same. S4. Cruise Phase Phase Lock: When the electric vertical takeoff and landing aircraft enters the cruise phase, all six rotors stop working, and the reference blades controlling all rotors are fixed at 0 degrees until the cruise phase ends and the aircraft re-enters the vertical takeoff or transition phase. S5. Real-time Phase Monitoring and Calibration: Throughout the phase control process, the motor speed signal and motor electrical angle signal of each rotor are collected in real time. Combined with the number of motor pole pairs N, the angle is calibrated. The calculation formula is: Actual mechanical phase angle = collected motor electrical angle ÷ number of motor pole pairs N, ensuring that the collected phase signal accurately reflects the actual phase state of the rotor. When it is detected that the rotor speeds are the same, but the phase difference between adjacent rotors in the same column deviates from the preset allowable range of 90 degrees, the phase adjustment program is immediately started to correct the phase difference to the preset range, ensuring the phase control accuracy.

2. The phase control method for a compound wing eVTOL multirotor according to claim 1, characterized in that, In step S2, the specific process of phase initialization is as follows: S21. Control the six rotors to be stationary, detect the initial position of the reference blades of each rotor, and if the reference blades are not in the 12 o'clock position, adjust them to the 12 o'clock position through motor drive. S22. Using rotor No. 1 as a reference, keep its reference blade at the 12 o'clock position, and control the reference blade of rotor No. 2 (2) to rotate to the 3 o'clock position, so that rotor No. 1 (1) and rotor No. 2 (2) form a 90-degree phase difference. S23. Using rotor No. 2 (2) as a reference, control the reference blade of rotor No. 3 (3) to rotate to a position with a 90-degree phase difference from the reference blade of rotor No. 2 (2), so as to ensure that the phase difference between rotor No. 2 (2) and rotor No. 3 (3) is 90 degrees. S24. Using rotor 1 (1) as a reference, control the reference blade of rotor 4 (4) to keep it in the same phase as rotor 1 (1), and at the same time start the reverse rotation mode of rotor 4 (4), which is opposite to the rotation direction of rotor 1 (1). S25. Using rotor No. 2 (2) as a reference, control the reference blade of rotor No. 5 (5) to maintain the same phase as rotor No. 2 (2), and at the same time start the reverse rotation mode of rotor No. 5 (5), which is opposite to the rotation direction of rotor No. 2 (2). S26. Using rotor No. 3 (3) as a reference, control the reference blade of rotor No. 6 (6) to keep it in the same phase as rotor No. 3 (3), and at the same time start the reverse rotation mode of rotor No. 6 (6), which is opposite to the rotation direction of rotor No. 3 (3). S27. After initialization, check whether the mechanical phase difference between adjacent rotors in the same column is 90 degrees ± 1 degree and whether the phases of corresponding rotors in two columns are the same, ensuring that the phase deviation is ≤ ± 0.5 degrees. If there is a deviation, repeat steps S22 to S26 until the preset requirements are met.

3. The phase control method for a compound wing eVTOL multirotor according to claim 1, characterized in that, In step S3, the criterion for judging stable rotation speed is: the absolute value of the deviation between the real-time rotation speed of each rotor and the preset target rotation speed is ≤ ±10 rpm, and the duration of this deviation state is ≥ 0.5s; when the rotation speed deviation exceeds this range, the phase maintenance program is paused, the rotation speed is adjusted to a stable state first, and then the phase maintenance is resumed.

4. The phase control method for a compound wing eVTOL multirotor according to claim 1, characterized in that, In step S5, the sampling frequency of phase monitoring is 100Hz-200Hz, and the preset allowable deviation range of the phase difference between adjacent rotors in the same column is ±5 degrees. When the phase difference is detected to deviate from this range, the response time of the phase adjustment program is ≤0.1s, the adjustment accuracy is ≤±1 degree, and the rotational speed stability of each rotor is not affected during the adjustment process.

5. The phase control method for a compound wing eVTOL multirotor according to claim 1, characterized in that, The number of motor pole pairs is N. The motor electrical angle is acquired through the motor's built-in Hall sensor or encoder, with an acquisition accuracy of ≤0.1 degrees, ensuring that the calculation accuracy of the actual phase angle is ≤0.1÷N degrees.

6. The phase control method for a compound wing eVTOL multirotor according to claim 1, characterized in that, The 90-degree phase difference between adjacent rotors in the same column is the mechanical phase difference, that is, the mechanical angle difference between two adjacent rotor reference blades is 90 degrees. The conversion relationship with the electric angle of the motor is: mechanical phase difference = electric angle difference ÷ N, where N is the number of motor pole pairs, to ensure the accuracy of phase detection and control.

7. The phase control method for a compound wing eVTOL multirotor according to claim 1, characterized in that, During the cruise phase, the criteria for stopping the six rotors are as follows: the flight speed of the electric vertical take-off and landing aircraft reaches the preset cruise speed, which is usually ≥120km / h, and the power output of the fixed wing and the thrust ducted fan reaches the preset stable value for a duration of ≥1s; at this time, the power of each rotor motor is cut off, and the rotor blades are fixed at 0 degrees by a mechanical locking mechanism to prevent the rotors from rotating due to airflow disturbance.

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