A cross double-rotor unmanned aerial vehicle blade phase difference online monitoring and fault-tolerant control method

Abstract

The present application belongs to the technical field of aircraft equipment, and particularly relates to a cross dual-rotor unmanned aerial vehicle blade phase difference online monitoring and fault-tolerant control method, comprising the following steps: collecting phase detection signals of a first rotor and a second rotor; filtering and shaping the phase detection signals; extracting a phase reference point and recording a time stamp; calculating phase angles of the first rotor and the second rotor; calculating a current phase deviation value; setting a flight state evaluation threshold value, and comparing the previous phase deviation value with the flight state evaluation threshold value in real time, and regulating and controlling a flight attitude according to a comparison result, comprising the following steps: judging whether the current phase deviation value is less than or equal to a first threshold value. The present application online monitors the cross dual-rotor unmanned aerial vehicle blade phase difference, and realizes an active control strategy of hierarchical fault-tolerant processing when a phase mismatch trend appears, so as to improve the safety and reliability of the cross dual-rotor unmanned aerial vehicle under complex working conditions.

Description

Technical Field

[0001] This invention belongs to the field of aircraft equipment technology, specifically relating to an online monitoring and fault-tolerant control method for the phase difference of the blades of a cross-rotor unmanned aerial vehicle, applicable to cross-rotor, interleaved-rotor, synchronous meshing-rotor, and unmanned flight platforms with overlapping rotor disk areas. Background Technology

[0002] Cross-rotor drones rely on two sets of rotors arranged in an alternating pattern to generate lift. Compared with traditional multi-rotor configurations, this layout features a compact structure, high lift efficiency, and excellent hovering performance, making it particularly suitable for scenarios such as low-altitude inspection, near-wall inspection, sling transport, photovoltaic cleaning, wind turbine blade inspection, and operations in complex environments.

[0003] However, because the rotor disks of the two sets of rotors overlap or intersect in close proximity in space, the blades must maintain a strictly preset phase relationship. In actual operation, factors such as motor speed fluctuations, transmission component clearances, timing belt slippage, sensor drift, control delays, or external gusts can all cause the phase difference between the two sets of blades to deviate from the safe range, thereby causing blade interference, collisions, or severe airframe vibrations, which in severe cases can lead to flight instability or even a crash.

[0004] Current research on UAV safety control focuses primarily on attitude stabilization, closed-loop speed management, battery monitoring, and return-to-home in case of malfunction, while insufficient attention is paid to the unique safety issues of blade phase synchronization in cross-rotor systems. Although some platforms rely on mechanical synchronization transmission mechanisms to maintain phase relationships, it is still difficult to avoid the effects of gear wear, transmission slack, assembly errors, and dynamic load impacts during long-term operation. Relying solely on mechanical structures cannot meet the requirements for real-time diagnostics and fault-tolerant control.

[0005] Therefore, there is an urgent need to develop an active control strategy that can monitor the blade phase difference online and implement graded fault-tolerant processing when the phase mismatch trend occurs, so as to improve the safety and reliability of cross-rotor UAVs under complex working conditions. Summary of the Invention

[0006] The purpose of this invention is to provide an online monitoring and fault-tolerant control method for the phase difference of the blades of a cross-rotor UAV. This method can monitor the phase difference of the blades of a cross-rotor UAV online and implement an active control strategy with graded fault tolerance when a phase mismatch trend occurs, so as to improve the safety and reliability of the cross-rotor UAV under complex working conditions.

[0007] The specific technical solution adopted by this invention is as follows: A method for online monitoring and fault-tolerant control of the phase difference between the blades of a cross-rotor UAV includes the following steps: Acquire phase detection signals from the first and second rotors; Filtering and shaping of the phase detection signal; Extract the phase reference point and record the timestamp; Calculate the phase angles of the first and second rotors; Calculate the current phase deviation value; Set a flight status evaluation threshold, compare the forward phase deviation value with the flight status evaluation threshold in real time, and adjust the flight attitude based on the comparison result.

[0008] As an optional approach, comparing the forward phase deviation value with the flight status evaluation threshold in real time and adjusting the flight attitude based on the comparison results includes the following steps: Determine whether the current phase deviation value is less than or equal to the first threshold. If yes, maintain the preset flight attitude; otherwise, enter the warning judgment state. Determine whether the current phase deviation value is less than or equal to the second threshold. If yes, execute the active correction state; otherwise, continue to determine whether the third threshold has been reached. If the current phase deviation value exceeds the third threshold or the abnormal duration exceeds the preset value, the system will enter a safe landing or emergency shutdown protection state.

[0009] As an optional solution, the flight control system records the fault and prompts for maintenance during the early warning judgment state.

[0010] As an optional solution, in the active correction state, the flight control system generates the speed correction amount based on the phase detection signals of the first rotor and the second rotor using proportional compensation, proportional integral compensation or model prediction compensation methods; At the same time, the first and second rotors make output corrections based on the rotational speed correction amount to restore the preset flight attitude between the first and second rotors.

[0011] As an optional approach, the calculation of the current phase deviation value involves normalizing the first rotor phase angle, the second rotor phase angle, and the safety phase difference to a preset angle range.

[0012] As an alternative, the phase detection signals of the first rotor and the second rotor are acquired by a phase detection unit and a speed detection unit located on the rotation shaft, drive shaft or hub end of the first rotor and the second rotor.

[0013] As an optional approach, the safe landing includes the following steps: The flight control system limits the rate of change of rotational speed of the first and second rotors to prevent attitude instability caused by rapid deceleration. Maintain the current aircraft attitude, select a safe landing point, and continuously monitor phase deviation, altitude, attitude angle, and motor status during descent.

[0014] As an optional approach, the safe landing includes the following steps: The flight control system limits the rate of change of rotational speed of the first and second rotors to prevent attitude instability caused by rapid deceleration. Maintain the current aircraft attitude, select a safe landing point, and continuously monitor phase deviation, altitude, attitude angle, and motor status during descent.

[0015] As an alternative, if the phase deviation between the first rotor and the second rotor is less than a third threshold or the abnormal duration does not exceed a preset value before the safe landing, the flight control system can exit the serious fault state and switch to a power-limited return or low-speed flight state.

[0016] An online monitoring and fault-tolerant control system for the phase difference of cross-rotor UAV blades, using the online monitoring and fault-tolerant control method for the phase difference of cross-rotor UAV blades as described above, includes: A phase detection unit is used to obtain the phase angle of the first rotor and the second rotor; The rotational speed detection unit is used to obtain the rotational speeds of the first rotor and the second rotor; The signal conditioning module is used to filter, debounce, shape, and convert the phase angle and rotation speed. The flight control system is used to acquire and process pulse signals and calculate the instantaneous phase angles of the first and second rotors based on timestamps. The fault-tolerant control instruction module is used to perform multi-level threshold judgment and graded fault-tolerant control of the first and second rotors based on the instantaneous phase angle.

[0017] An electronic device, the electronic device comprising: At least one processor; and a memory communicatively connected to the at least one processor; The memory stores a computer program that can be executed by the at least one processor, which is then executed by the at least one processor to enable the at least one processor to perform the online monitoring and fault-tolerant control method for the phase difference of the cross-rotor UAV blades.

[0018] The technical effects achieved by this invention are as follows: This invention provides an online monitoring and fault-tolerant control method for the phase difference of the blades of a cross-rotor UAV. It can monitor the phase difference of the blades of the cross-rotor UAV online and implement an active control strategy with graded fault tolerance when the phase mismatch trend occurs, so as to improve the safety and reliability of the cross-rotor UAV under complex working conditions.

[0019] This invention provides an online monitoring and fault-tolerant control system for the phase difference of the blades of a cross-rotor UAV, which can monitor the risk of blade phase mismatch unique to cross-rotor UAVs online.

[0020] This invention provides an online monitoring and fault-tolerant control system for the phase difference of the propeller blades of a cross-rotor UAV. It adopts multi-level threshold judgment and graded fault-tolerant control to avoid slight disturbances directly triggering over-protection.

[0021] The present invention provides an online monitoring and fault-tolerant control method for the phase difference of cross-rotor UAV blades, which improves the reliability of fault identification by jointly judging phase deviation, rotational speed difference and abnormal duration.

[0022] This invention provides an online monitoring and fault-tolerant control system for the phase difference of cross-rotor UAV blades, which can reduce the rotational speed or ensure safe landing before actual blade collision, thereby improving flight safety.

[0023] The present invention provides an online monitoring and fault-tolerant control method for the phase difference of the blades of a cross-rotor UAV, which does not rely on complex mechanical modifications and can be implemented through sensors and flight control algorithms, making it easy to integrate on existing cross-rotor platforms. Attached Figure Description

[0024] Figure 1 This is a flowchart of an online monitoring and fault-tolerant control method for the phase difference of cross-rotor UAV blades according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the electronic device in Embodiment 1 of the present invention; Figure 3 This is a system block diagram of an online monitoring and fault-tolerant control system for the phase difference of the propeller blades of a cross-rotor UAV according to Embodiment 2 of the present invention; Figure 4 This is a schematic diagram showing the distribution of the cross-rotor UAV detection units in Embodiment 2 of the present invention; Figure 5 This is a schematic diagram of the hierarchical fault-tolerant control state transition in Embodiment 2 of the present invention; Figure 6 This is a schematic diagram of the phase deviation threshold determination in Embodiment 2 of the present invention; Figure 7 This is a flowchart of safe landing and fault data recording in Embodiment 2 of the present invention. Detailed Implementation

[0025] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.

[0026] Example 1: like Figures 1-2 As shown, a method for online monitoring and fault-tolerant control of the phase difference of cross-rotor UAV blades includes the following steps: Phase detection units are respectively installed at the rotation shaft, transmission shaft or hub end of the first rotor and the second rotor. The phase detection units are used to obtain the phase angle of the first rotor and the second rotor. A speed detection unit is also provided to obtain the speed of the first rotor and the second rotor. Acquire phase detection signals from the first and second rotors; Filtering and shaping of the phase detection signal; Extract the phase reference point and record the timestamp; Calculate the phase angles of the first rotor and the second rotor to obtain the phase angle of the first rotor. Phase angle of the second rotor ; Set safe phase difference Calculate the current phase deviation value based on the safe phase difference. The phase angles of the first rotor, the second rotor, and the safety phase difference are normalized to a preset angle range. The calculation process is as follows: (1) Formula (1) in, This indicates that the angle has been normalized to a preset angle range; Determine whether the current phase deviation value is less than or equal to the first threshold. If yes, the preset flight attitude is maintained; otherwise, the system enters a warning judgment state, during which the flight control system records the fault and prompts for maintenance. Determine whether the current phase deviation value is less than or equal to the second threshold. If yes, then execute the active correction state; otherwise, continue to determine whether the third threshold has been reached. In active correction mode, the flight control system generates speed correction amounts based on the phase detection signals of the first and second rotors, using proportional compensation, proportional-integral compensation, or model prediction compensation methods. The calculation process is as follows: Formula (2): Formula (2) in, , , These are the control gains corresponding to phase deviation, speed difference, and rate of change of phase deviation, respectively. At the same time, the first and second rotors make output corrections based on the rotational speed correction amount in order to restore the preset flight attitude between the first and second rotors; If the current phase deviation value exceeds the third threshold If the abnormal duration exceeds the preset value, it will enter the safe landing or emergency shutdown protection state.

[0027] An electronic device, see Figure 2 The electronic device includes: At least one processor; and memory that is communicatively connected to at least one processor; The memory stores a computer program that can be executed by at least one processor, which enables the at least one processor to execute the method for online monitoring and fault-tolerant control of the phase difference between the blades of a cross-rotor UAV.

[0028] The processors in the aforementioned electronic devices can be of various types, such as CPUs, GPUs, or TPUs, to adapt to different computing needs and ensure efficient processing of multidimensional complex data. The memory can be of various types, such as RAM, ROM, or SSDs, to store large amounts of data, support fast read and write operations, and ensure stable system operation. In addition, the electronic devices are equipped with high-precision sensors to monitor environmental changes in real time, ensuring the accuracy and timeliness of data acquisition, as well as arithmetic units, input devices, and output devices. The arithmetic unit can be an FPGA or ASIC, responsible for high-speed parallel computing. Input devices such as keyboards and touch screens facilitate operation, while output devices such as displays and printers intuitively display results. The entire system works in tandem to improve the response speed and decision support capabilities of the online monitoring and fault-tolerant control method for the phase difference of the cross-rotor UAV blades.

[0029] Example 2: like Figures 3-7 As shown, an online monitoring and fault-tolerant control system for the phase difference of cross-rotor UAV blades, using the online monitoring and fault-tolerant control method for the phase difference of cross-rotor UAV blades provided in Embodiment 1, includes: Phase detection unit, see Figure 4 It is set at the rotation shaft, drive shaft or hub end of the first rotor and the second rotor to obtain the phase angle of the first rotor and the second rotor. The phase detection unit can be a Hall sensor, magnetic encoder, photoelectric encoder, absolute encoder or proximity switch.

[0030] Speed ​​detection unit, see Figure 3 and Figure 4 It is set at the rotation shaft, drive shaft or hub end of the first rotor and the second rotor to obtain the rotational speed of the first rotor and the second rotor. The rotational speed detection unit can share the encoding signal with the phase detection unit, or it can be set up separately.

[0031] Signal conditioning module, see Figure 3 It is used for filtering, debouncing, shaping, and level conversion of phase angle and rotation speed.

[0032] Flight control system, see Figure 3 It is used to acquire and process pulse signals and calculate the instantaneous phase angle of the first and second rotors based on timestamps.

[0033] Fault-tolerant control instruction module, see Figure 3 It is used for multi-level threshold judgment and graded fault-tolerant control of the first and second rotors based on the instantaneous phase angle.

[0034] For details, see Figure 3 and Figure 6 Hierarchical fault-tolerant control includes: First threshold In the area of ​​slight deviation warning, the flight control system records the fault and prompts for maintenance. Second threshold In the corresponding active correction zone, the flight control system adjusts the output of the first and second electronic speed controllers to change the output power of the first and second motors, so that the rotational speeds of the first and second rotors tend to match and the phase deviation is brought back to a safe range. Third threshold In response to severe anomalies, the flight control system limits the maximum rotor speed, reduces aerodynamic loads, and enters a safe landing mode based on flight altitude and attitude.

[0035] As an alternative embodiment, see 5 and Figure 7 A safe landing includes the following steps: If the phase deviation between the first rotor and the second rotor is less than the third threshold or the abnormal duration exceeds the preset value, a serious abnormality is triggered. The flight control system limits the rate of change of rotational speed of the first and second rotors to prevent attitude instability caused by rapid deceleration. Maintain the current aircraft attitude and select a safe landing point for descent; During descent, phase deviation, altitude (e.g., real-time monitoring of ground distance via distance sensor, converted into altitude value), attitude angle, and motor status are continuously monitored. If the phase deviation between the first rotor and the second rotor is less than the third threshold or the abnormal duration does not exceed the preset value (returning to the preset flight attitude), the flight control system can exit the serious fault state and switch to the power-limited return or low-speed flight state. Determine if grounding is not detected; if not, continue monitoring during the descent process. After landing, the flight control system cuts off the output of the first and second rotors and records the fault data for subsequent maintenance and fault analysis.

[0036] In summary, this invention can be used to control both independently driven dual-motor cross-rotor UAVs and mechanically synchronously driven cross-rotor UAVs. When mechanically synchronous transmission is used, the phase detection unit can be used to monitor whether backlash accumulation, timing belt slippage, or assembly loosening occurs in the transmission system; when dual-motor independent drive is used, the phase detection unit and the flight control system work together to achieve electronic phase synchronization control.

[0037] The above description is merely an optional embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention, unless otherwise specified or limited, shall be implemented according to conventional means in the art.

Claims

1. A method for online monitoring and fault-tolerant control of the phase difference between the blades of a cross-rotor unmanned aerial vehicle, characterized in that, Includes the following steps: Acquire phase detection signals from the first and second rotors; Filtering and shaping of the phase detection signal; Extract the phase reference point and record the timestamp; Calculate the phase angles of the first and second rotors; Calculate the current phase deviation value; Set a flight status evaluation threshold, compare the forward phase deviation value with the flight status evaluation threshold in real time, and adjust the flight attitude based on the comparison result.

2. The method for online monitoring and fault-tolerant control of the phase difference of cross-rotor UAV blades according to claim 1, characterized in that: The step of comparing the forward phase deviation value with the flight status evaluation threshold in real time and adjusting the flight attitude based on the comparison result includes the following steps: Determine whether the current phase deviation value is less than or equal to the first threshold. If yes, maintain the preset flight attitude; otherwise, enter the warning judgment state. Determine whether the current phase deviation value is less than or equal to the second threshold. If yes, execute the active correction state; otherwise, continue to determine whether the third threshold has been reached. If the current phase deviation value exceeds the third threshold or the abnormal duration exceeds the preset value, the system will enter a safe landing or emergency shutdown protection state.

3. The method for online monitoring and fault-tolerant control of the phase difference of cross-rotor UAV blades according to claim 1, characterized in that: In the active correction state, the flight control system generates the speed correction amount based on the phase detection signals of the first rotor and the second rotor, using proportional compensation, proportional integral compensation or model prediction compensation methods. At the same time, the first and second rotors make output corrections based on the rotational speed correction amount to restore the preset flight attitude between the first and second rotors.

4. The method for online monitoring and fault-tolerant control of the phase difference of cross-rotor UAV blades according to claim 3, characterized in that: The calculation of the current phase deviation value involves normalizing the first rotor phase angle, the second rotor phase angle, and the safety phase difference to a preset angle range.

5. The method for online monitoring and fault-tolerant control of the phase difference of cross-rotor UAV blades according to claim 1, characterized in that: The phase detection signals of the first rotor and the second rotor are acquired by a phase detection unit and a rotational speed detection unit located on the rotation shaft, transmission shaft or hub end of the first rotor and the second rotor.

6. The method for online monitoring and fault-tolerant control of the phase difference of cross-rotor UAV blades according to claim 1, characterized in that, The safe landing includes the following steps: The flight control system limits the rate of change of rotational speed of the first and second rotors to prevent attitude instability caused by rapid deceleration. Maintain the current aircraft attitude, select a safe landing point, and continuously monitor phase deviation, altitude, attitude angle, and motor status during descent.

7. The method for online monitoring and fault-tolerant control of the phase difference of cross-rotor UAV blades according to claim 1, characterized in that: If the phase deviation between the first rotor and the second rotor is less than the third threshold or the abnormal duration does not exceed the preset value before the safe landing, the flight control system can exit the serious fault state and switch to the power-limited return or low-speed flight state.

8. The method for online monitoring and fault-tolerant control of the phase difference of cross-rotor UAV blades according to claim 1, characterized in that: After a safe landing, the flight control system cuts off the output of the first and second rotors and records fault data for subsequent maintenance and fault analysis.

9. A cross-rotor unmanned aerial vehicle (UAV) blade phase difference online monitoring and fault-tolerant control system, using the cross-rotor UAV blade phase difference online monitoring and fault-tolerant control method as described in any one of claims 1-8, comprising: A phase detection unit is used to obtain the phase angle of the first rotor and the second rotor; The rotational speed detection unit is used to obtain the rotational speeds of the first rotor and the second rotor; Its characteristic is that it further includes: The signal conditioning module is used to filter, debounce, shape, and convert the phase angle and rotation speed. The flight control system is used to acquire and process pulse signals and calculate the instantaneous phase angles of the first and second rotors based on timestamps. The fault-tolerant control instruction module is used to perform multi-level threshold judgment and graded fault-tolerant control of the first and second rotors based on the instantaneous phase angle.

10. An electronic device, characterized in that, The electronic device includes: At least one processor; and a memory communicatively connected to the at least one processor; The memory stores a computer program that can be executed by the at least one processor, which is then executed by the at least one processor to enable the at least one processor to perform the online monitoring and fault-tolerant control method for the phase difference of the cross-rotor UAV blades as described in any one of claims 1 to 8.

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