Automatic control method of four-power-source tilting aircraft

Abstract

The invention discloses an automatic control method of a four-power-source tiltable aircraft, relates to the technical field of flight control of tiltable aircrafts, is realized based on a PX4 flight control system, and is suitable for a tiltable aircraft provided with four independent tiltable power sources and corresponding tilting execution mechanisms. According to the method, through configuration of a tilting angle control module, a power distribution module and a full-stage flight logic scheduling module, full-stage automatic control of vertical take-off and landing, suspension, horizontal take-off, fixed-point horizontal flight, automatic cruise, one-key return flight, fixed-angle flight, power source fault handling and the like is achieved. Smooth transition of all flight modes is achieved, the stability of the attitude, the height and the position of the tiltable aircraft in different flight stages is maintained, meanwhile, the functions of automatic obstacle avoidance, fault emergency and the like are integrated, flight safety is guaranteed, flight stability and applicability are improved, and the method can be widely applied to various tiltable aircraft operation scenes.

Description

Technical Field

[0001] This invention relates to the field of tilt-rotor aircraft flight control technology, specifically to an automatic control method for a four-power-source tilt-rotor aircraft. Background Technology

[0002] Tiltrotor aircraft combine the advantages of multi-rotor vertical takeoff and landing / hovering with fixed-wing high-speed cruise, and have become an important development direction in the field of tiltrotor aircraft. During mode switching, the aerodynamic characteristics and control logic of such tiltrotor aircraft undergo significant changes, placing higher demands on the autonomy and coordination of the control system.

[0003] Existing technologies have explored various tilt-rotor configurations and control schemes. For example, invention patent CN105083551B discloses a tiltrotor aircraft and its control method, which achieves vertical takeoff and landing and horizontal flight through the cooperation of tilt mechanism and pitch mechanism. However, this scheme focuses on mechanism design and basic operation, and does not propose an integrated control process for fully autonomous, multi-stage mission profiles, nor does it solve the problem of coordinated allocation and smooth transition during mode switching of four power sources. In addition, invention patent CN119916700A proposes a passive fault-tolerant control method and system for tiltrotor aircraft based on a nonlinear variable parameter model. This method focuses on designing a fault-tolerant controller for actuator failures, improving system safety, but its control method does not involve full-mission automatic scheduling and unified multi-mode control allocation for the special configuration where all four power sources are tiltable, making it difficult to achieve fully autonomous flight from vertical takeoff and landing, hovering, transition to cruise, and return.

[0004] As can be seen from the existing technologies described above, although some progress has been made in tiltrotor aircraft, there is still a lack of an integrated control method for four-power-source fully tiltable configurations that can achieve autonomous control throughout the entire flight phase without human intervention and can collaboratively manage the tilt angles and thrust of the four power sources. This results in a heavy operational burden and an unstable mode switching process for tiltrotor aircraft when performing complex missions, limiting their application effectiveness and reliability.

[0005] Therefore, there is an urgent need in this field for a control method that can cover the entire mission profile of a four-powered tilt-rotor aircraft and achieve highly automated flight, in order to address the shortcomings of existing technologies in terms of global autonomy and control smoothness. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an automatic control method for a four-power-source tiltable aircraft. By configuring tilt angle control, power distribution, and full-stage flight logic scheduling modules based on the PX4 flight control system, the tilt angle and thrust of the four independent tiltable power sources are coordinated and controlled to achieve autonomous control and smooth mode transition throughout the entire flight phase, maintaining flight attitude, altitude, and position stability, thus overcoming the lack of fully autonomous integrated control in existing technologies.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: an automatic control method for a four-power-source tiltable aircraft, the method being implemented based on the PX4 flight control system. The four-power-source tiltable aircraft includes four independently tiltable power sources and corresponding tilting actuators. The method includes the following steps:

[0008] Step 1: Vertical Take-off and Landing Control: Controlling the tilt angle of the four power sources. Vertical takeoff or vertical landing can be achieved by adjusting the rotation speed of the four power sources, while maintaining the stability of the tiltable aircraft's attitude.

[0009] Step 2, Suspension Attitude Control: In At the same time, based on the attitude, position and altitude data collected by the sensors, the required attitude correction amount is calculated, and the roll, pitch, yaw attitude, altitude and position stability of the tiltable aircraft is maintained by adjusting the speed difference of the four power sources.

[0010] Step 3, Horizontal Takeoff Control: Starting from the hovering state, continuously adjust at a preset rate to ensure the tilt angle of the four power sources is changed without abrupt changes. Adjusting from 0° to 90° simultaneously increases the total thrust of the four power sources, allowing the tilting aircraft to accelerate horizontally to a preset cruise speed.

[0011] Step 4, Fixed-point horizontal flight control: In In horizontal flight, the current coordinates are compared with the target fixed point coordinates, and the thrust of the power source and the control surfaces are adjusted to maintain the stability of the tiltable aircraft at the target fixed point position.

[0012] Step 5, Horizontal Landing Control: Starting from horizontal flight, continuously adjust at a preset rate to ensure the tilt angle of the four power sources is changed without abrupt changes. Adjusting from 90° to 0° simultaneously reduces the total thrust of the four power sources, causing the tilting aircraft to decelerate and switch to vertical landing mode.

[0013] Step Six: Fixed Angle Flight Control: Lock the user-defined fixed tilt angle. ,in and combined with this The dynamic vector is adjusted to regulate the speed difference between the four power sources in order to maintain the attitude stability of the tiltable aircraft.

[0014] Step 7: Automatic Cruise Control: Analyze the preset multi-waypoint path and control the tilt-rotor aircraft in... In horizontal flight mode, fly in waypoint sequence;

[0015] Step 8, One-click return control: Store the return reference point, and after triggering the return, control the tiltable aircraft to fly towards the return reference point. When the tiltable aircraft reaches the preset altitude and horizontal distance threshold above the return reference point, switch to landing mode to complete the return.

[0016] Step Nine, Power Source Failure Response Control: When one or more power sources are detected to have failed, the tilt angle of the power sources that are not experiencing failure will be adjusted. Adjust to 90°, control the flight attitude through the control surfaces in fixed-wing mode, and perform a gliding emergency landing;

[0017] In this invention, the PX4 flight control system is selected as the control core. Its open-source nature facilitates the integration of newly added tilt angle control, power distribution and full-stage flight logic scheduling modules. It also natively supports the fusion of data from multiple sensors such as IMU, GPS, and barometer, and has high-precision attitude calculation and real-time control capabilities. It can accurately coordinate the tilt angle adjustment and speed distribution of four independent tilt power sources to ensure smooth transition of each flight mode and stable flight attitude.

[0018] Furthermore, the PX4 flight control system includes:

[0019] The tilt angle control module receives commands during the flight phase and outputs servo control signals to the tilt actuator to lock or adjust the tilt angle of the four power sources. ;

[0020] The power distribution module is used to calculate the target rotational speed of each of the four power sources based on the flight phase and the output of the attitude controller;

[0021] The full-stage flight logic scheduling module is used to trigger and switch between vertical takeoff and landing, hovering, horizontal takeoff, fixed-point horizontal flight, horizontal landing, fixed-angle flight, automatic cruise, and the one-key return control in step eight.

[0022] Furthermore, the tilt angle control module receives feedback signals from the servo motor of the tilt actuator to control the tilt angle of the four power sources. Closed-loop control is implemented to correct angle drift.

[0023] Furthermore, in step one, during vertical takeoff, the rotational speed of the four power sources is gradually increased from the lowest value to the hovering speed; during vertical landing, the rotational speed of the four power sources is gradually decreased from the hovering speed; when the PX4 flight control system detects a ground contact signal determined by data collected by the barometer and inertial measurement unit mounted on the tilt-rotor aircraft, it controls the power sources to cut off power.

[0024] The barometer and inertial measurement unit are used to collect roll angle, pitch angle, yaw angle and three-axis angular velocity data of the tiltable aircraft.

[0025] Furthermore, in steps three and five, the tilt angle The adjustment rate is constant or varies according to a preset acceleration curve.

[0026] Furthermore, the triggering conditions for the one-key return-to-home control in step eight include: receiving a manual return-to-home command sent by the ground station, the PX4 flight control system detecting that the remaining battery power is lower than a preset threshold, or the communication interruption duration between the PX4 flight control system and the ground station exceeding a preset time threshold.

[0027] Furthermore, in step seven, when the obstacle avoidance sensor equipped on the tilt-plane detects an obstacle, the waypoint navigation module generates a temporary detour waypoint, controls the tilt-plane to fly along the temporary detour waypoint, and after avoiding the obstacle, controls the tilt-plane to return to the next waypoint on the original cruise path.

[0028] Furthermore, the power distribution module is based on a fixed tilt angle. The total thrust Decomposed into vertical lift components With horizontal thrust component Based on the requirements of the vertical lift component and the horizontal thrust component, the target rotational speed of the four power sources is calculated.

[0029] Furthermore, the data collected by the sensors in step two includes roll angle, pitch angle, yaw angle and three-axis angular velocity collected by the IMU inertial measurement unit, latitude and longitude coordinates collected by the GPS positioning module, and altitude data collected by the barometer.

[0030] Furthermore, in step nine, the roll, pitch, and yaw attitudes of the tilt-rotor aircraft are controlled by adjusting the deflection angles of the aileron servo, elevator servo, and rudder servo.

[0031] Compared with existing technologies, this automatic control method for a four-power-source tiltable aircraft has the following advantages:

[0032] I. This invention constructs a tilt angle control module, a power distribution module, and a full-stage flight logic scheduling module based on the PX4 flight control system, forming an integrated control framework covering the entire flight mission profile, including vertical takeoff and landing, hovering, horizontal takeoff, stationary flight, cruise, and return. It coordinates and regulates the tilt angle and thrust distribution of four independent tiltable power sources, achieving smooth transitions between various flight modes, significantly reducing the operational burden, improving the autonomy and coordination of tiltable aircraft flight, and ensuring attitude and position stability in different flight stages.

[0033] Second, when a power source failure is detected, the system can quickly switch the remaining normal power source to fixed-wing mode, stabilize the flight attitude through control surfaces and implement an emergency landing. During the cruise, it can detect obstacles through obstacle avoidance sensors and generate temporary waypoints to avoid collision risks. When the return-to-home trigger conditions are met, it can autonomously fly toward the reference point and land accurately, adapting to diverse operational needs.

[0034] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0036] Figure 1 This is a step diagram of the present invention;

[0037] Figure 2 This is a diagram showing the system architecture and flight mode control relationship of the present invention;

[0038] Figure 3 This is a flowchart illustrating the operation of the present invention. Detailed Implementation

[0039] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0040] Example 1

[0041] like Figure 1 and Figure 2As shown, this embodiment discloses an automatic control method for a four-power-source tiltable aircraft. This method is based on the PX4 open-source flight control system and is applicable to tiltable aircraft equipped with four independently tiltable power sources and corresponding tilt actuators. The tiltable aircraft body also includes a sensor group, an aerodynamic control surface servo mechanism, and a landing gear system. The sensor group includes an IMU inertial measurement unit, a GPS positioning module, a magnetic compass, a barometer, and optional obstacle avoidance sensors. The aerodynamic control surface servo mechanism is used to control the deflection of the ailerons, elevators, and rudder. The tilt actuator is driven by a servo motor, enabling precise adjustment and locking of the power source tilt angle.

[0042] This embodiment constructs an automatic control framework covering the entire flight mission profile by adding a tilt angle control module, a power distribution module, and a full-stage flight logic scheduling module to the PX4 native firmware. The specific implementation methods of each control step are described in detail below.

[0043] In this embodiment, the software module configuration of the PX4 flight control system is the core of achieving fully autonomous control. The functions and cooperation logic of each newly added module are as follows:

[0044] Tilting Angle Control Module: Receives flight phase commands from the full-stage flight logic scheduling module, outputs servo control signals to the tilt actuator to lock or adjust the tilt angle of the power source; simultaneously receives servo feedback signals from the tilt actuator and corrects angle drift through closed-loop control to ensure tilt angle control accuracy.

[0045] Power distribution module: Based on the current flight phase, the output of the attitude controller and the tilt angle, it calculates the target rotational speed of the four power sources to achieve coordinated thrust distribution and ensure the dynamic balance between vertical lift and horizontal thrust.

[0046] Full-stage flight logic scheduling module: As the control center, it receives ground station instructions or sensor trigger signals, triggers and switches between various flight stages such as vertical takeoff and landing, hovering, and horizontal takeoff according to preset logic, and coordinates the working sequence of each module.

[0047] Waypoint navigation module: parses the waypoint data preset by the ground station, generates flight path instructions, and provides navigation support for automatic cruise and one-click return.

[0048] Fault detection module: Real-time monitoring of power source operating status, sensor data validity and communication link status; triggers corresponding fault response logic when an anomaly is detected.

[0049] The vertical takeoff and landing control adopts multi-rotor control logic, which achieves attitude stabilization and lift control through coordinated adjustment of the power source speed. The specific implementation process is as follows:

[0050] When the ground station sends the "vertical takeoff" command, the full-stage flight logic scheduling module triggers "vertical takeoff mode" and sends an angle lock command to the tilt angle control module. The tilt angle control module outputs servo control signals to maintain the tilt angle of the four power sources at a constant value. At this point, the thrust of the power source is vertically upward, providing vertical lift for the tilt-rotor aircraft.

[0051] The power distribution module receives altitude data from the barometer and uses incremental adjustment logic to control the power source speed: initially, the power source speed is at its lowest value, then gradually increases to the hovering speed to ensure a smooth takeoff for the tilt-type aircraft. During speed adjustment, the attitude control module uses roll angle data collected by the IMU. Pitch angle and yaw angle The data is used to adjust the speed difference between the four power sources through a PID control algorithm to maintain attitude stability. The core algorithm of attitude control is as follows:

[0052] For roll attitude control, its control output quantity The formula for calculation is:

[0053]

[0054] in, To determine the desired roll attitude angle, The actual roll angle measured by the IMU. This is the proportional coefficient for roll control, used for rapid response to attitude deviations. The integral coefficient for roll control is used to eliminate static deviation. The differential coefficient for roll control is used to suppress attitude oscillations.

[0055] The algorithm for pitch attitude control is the same as that for roll attitude control; only the relevant parameters need to be replaced with the parameters corresponding to the pitch angle. , , , Its control output is .

[0056] Output of yaw attitude control The calculation formula is:

[0057]

[0058] in , The initial heading angle at takeoff, This is the actual measured yaw angle.

[0059] Target speeds of the four power sources , , , From the reference speed The result is obtained by superimposing the outputs of each attitude control, and the specific allocation logic is as follows:

[0060]

[0061]

[0062]

[0063]

[0064] Reference speed The power distribution module dynamically adjusts the altitude based on the deviation between the barometer-measured altitude and the desired altitude to ensure a smooth vertical ascent speed for the tilt-rotor aircraft.

[0065] During vertical descent, after receiving the "vertical descent" command, maintain the tilt angle. Unchanged. The power distribution module gradually reduces the reference speed of the four power sources at a preset rate. The attitude control module continues to maintain stable roll, pitch, and yaw attitude using the aforementioned PID algorithm. When the ground clearance measured by the barometer reaches the preset landing threshold and the IMU detects a sudden change in vertical acceleration, it is determined that the tilting aircraft is about to touch down. The power distribution module immediately cuts off the power source to complete the landing process.

[0066] Suspension attitude control This is achieved in multi-rotor mode, with the core objective of maintaining the position, altitude, and attitude stability of the tilt-rotor aircraft. The specific implementation is as follows:

[0067] After the hover state is triggered, the PX4 flight control system collects data from various sensors in real time: the IMU continuously outputs the roll angle. Pitch angle Yaw angle and the corresponding three-axis angular velocities; GPS output of the real-time position coordinates of the tiltable aircraft. Barometer outputs real-time altitude .

[0068] Attitude stabilization control uses the PID algorithm from the vertical takeoff and landing phase to ensure... , Stable around 0 Stabilize at the initial heading angle. Position stabilization control is achieved through a position-velocity dual-loop PID controller. First, the position deviation is calculated:

[0069]

[0070]

[0071] in The coordinates of the target position in the suspended state.

[0072] Convert positional deviation into horizontal speed command:

[0073]

[0074]

[0075] in , , and , , These are the proportional coefficient, integral coefficient, and derivative coefficient for position control in the X and Y directions, respectively.

[0076] The speed control loop is based on the actual horizontal speed measured by GPS. The deviation from the speed command generates an attitude angle correction, which is then added to the desired angle for attitude control to achieve closed-loop position stabilization.

[0077] Altitude stability control is achieved by comparing barometer data with the desired altitude. The deviation calculation, its reference speed adjustment amount for:

[0078]

[0079] in , , For highly controlled PID parameters, Used to dynamically correct the reference speed of the four power sources To ensure high stability.

[0080] Horizontal takeoff control achieves a smooth transition from a hovering state to a fixed-wing level flight state. The core of this system is the smooth adjustment of the tilt angle and the coordinated increase of total thrust. The specific implementation is as follows:

[0081] When the ground station sends a "horizontal takeoff" command, or when the full-stage flight logic scheduling module detects stable hovering, the "horizontal takeoff mode" is triggered. At this time, the tilt angle control module adjusts the tilt angle of the power source according to a preset pattern. The angle is gradually increased from 0° to 90°. To avoid attitude oscillations caused by sudden changes in the dynamic vector, The adjustment adopts a three-segment curve of uniform acceleration-uniform speed-uniform deceleration, and its variation law is as follows:

[0082]

[0083] in, Angular acceleration is the angle of tilt. The duration of the uniform acceleration phase, , The duration of the uniform velocity phase, This is the moment when the tilt is complete. .

[0084] While adjusting the tilt angle, the power distribution module simultaneously increases the total thrust of the four power sources. This is to balance the changes in the vertical lift component during the tilting process. Total thrust The calculation is based on the principle of force balance in the vertical direction:

[0085]

[0086] in, For the gravity of a tilting aircraft, The vertical aerodynamic drag is proportional to the square of the flight speed and can be calibrated through aerodynamic characteristic tests. For tilt angle The corresponding vertical lift component coefficient.

[0087] The power distribution module calculates the target total thrust in real time according to the above formula. The thrust is evenly distributed among the four power sources to ensure the thrust of each power source i. Simultaneously, the speed control module, in conjunction with the horizontal speed data collected by GPS, adjusts the horizontal thrust component. This allows the horizontal speed of the tilting aircraft to gradually increase to the preset cruise speed.

[0088] Throughout the entire horizontal takeoff transition, the attitude control module works continuously, combining the attitude data collected by the IMU with the tilt angle data fed back by the servos, dynamically adjusting the speed difference of each power source and the deflection of the aerodynamic control surfaces to suppress attitude oscillations and ensure a smooth transition.

[0089] Fixed-point level flight control In fixed-wing mode, this is achieved through the coordination of attitude control and position control to maintain the stability of the tiltable aircraft at the target fixed point. The specific implementation is as follows:

[0090] Upon receiving the "fixed-point flight" command, the full-stage flight logic scheduling module switches to "fixed-point level flight mode," at which point the power source tilt angle remains at 90°, and the total thrust provides the power for level flight.

[0091] Attitude control employs the angle-angular rate dual-loop PID control commonly used in fixed-wing aircraft.

[0092] Inner loop control of angular rate: roll angular rate measured by IMU Pitch rate yaw rate For feedback, a servo control signal is output, whose roll rate control output... for:

[0093]

[0094] in The desired roll rate command is output from the outer angle loop; , , These are the PID parameters for roll rate control; This is the command for the aileron deflection angle.

[0095] Pitch rate control output and yaw rate control output The algorithm is the same as above, only the corresponding angular rate parameter and PID coefficient need to be replaced.

[0096] Outer loop angle control: Based on the attitude angle expectation command output by the position control module, the actual attitude angle measured by the IMU is compared to generate the angular rate expectation command. Taking roll angle as an example:

[0097]

[0098] in The roll angle expectation command is generated by the position control module. , , These are the PID parameters for roll angle control.

[0099] Position control employs a position-velocity dual-loop structure, similar to the position control logic in hovering, but requires parameter adaptation to the aerodynamic characteristics of a fixed wing. Target stationary coordinates. The location is set by the ground station, and GPS collects the actual position in real time. The position deviation is converted into the desired attitude angle command through a dual-loop PID controller, and then the position is stabilized through attitude control.

[0100] Horizontal landing control achieves a smooth transition from fixed-wing horizontal flight to vertical landing. Its core lies in the smooth, reverse adjustment of the tilt angle and the coordinated reduction of total thrust. The specific implementation is as follows:

[0101] Upon receiving the "horizontal descent" command, the full-stage flight logic scheduling module switches to "horizontal descent mode." First, the speed control module gradually decelerates the tilt-type aircraft's horizontal speed to a preset transition speed by reducing the total thrust of the power source and adjusting the aerodynamic control surfaces.

[0102] Subsequently, the tilt angle control module adjusts the tilt angle according to a three-segment curve, which is the opposite of the horizontal takeoff phase. The temperature gradually decreases from 90° to 0°, and its pattern of change is similar to that of the horizontal takeoff phase. The formula is symmetrical; simply replace the target angle from 90° to 0°.

[0103] During the tilt angle adjustment process, the power distribution module simultaneously reduces the total thrust. Ensure vertical force balance:

[0104]

[0105] The parameters are defined in the same way as those in the horizontal takeoff phase. The total thrust of the target is calculated in real time using this formula to prevent tilt-type aircraft from experiencing abnormal altitude gain during the transition.

[0106] When tilt angle When the temperature drops to 0° and the horizontal speed is below the preset threshold, the full-stage flight logic scheduling module switches to "vertical landing mode". The subsequent process is the same as the landing process in vertical take-off and landing control. The smooth landing is achieved by gradually reducing the speed of the power source. After landing, the power source is de-energized.

[0107] Fixed-angle flight control allows users to set any tilt angle between 0° and 90°, enabling the tilting aircraft to achieve stable flight at that fixed angle. The specific implementation is as follows:

[0108] Users input a fixed tilt angle via ground station. The full-stage flight logic scheduling module triggers the "fixed angle flight mode" and will The signal is sent to the tilt angle control module. The tilt angle control module outputs a servo control signal, driving the power source to tilt to... After locking, it performs closed-loop control by receiving feedback signals from the servo motor to correct angle drift and ensure... The control precision.

[0109] Power distribution module according to Calculate the vertical lift component and the horizontal thrust component of the total thrust:

[0110]

[0111]

[0112] in The total thrust is set according to the flight mission requirements.

[0113] Attitude control module combined The dynamic vector direction is adjusted using a hybrid control strategy: when When approaching 0°, the speed difference control in multi-rotor mode is the primary method, supplemented by aerodynamic control surfaces; when When approaching 90°, aerodynamic control is the primary method, supplemented by speed difference control; when When in the intermediate range, the two control methods work together. The attitude control output is the superposition of the speed difference correction and the control surface deflection angle command, ensuring attitude stability at a fixed tilt angle.

[0114] Automatic cruise control enables tilt-type aircraft to fly autonomously along multi-waypoint paths preset by the ground station, supporting obstacle avoidance capabilities. Specifically, the user presets the coordinates of multiple waypoints along the cruise path using the ground station. Upon receiving the "Auto Cruise" command and setting the cruise speed, the full-stage flight logic scheduling module switches to "Auto Cruise Mode" and triggers the level takeoff procedure, allowing the tilt-rotor aircraft to enter... Horizontal flight state.

[0115] The waypoint navigation module parses the preset waypoint data and uses a geodetic coordinate system-based trajectory planning algorithm to calculate the reference heading angle between the current waypoint and the next waypoint. :

[0116]

[0117] in The coordinates of the current waypoint The coordinates are for the next waypoint.

[0118] The attitude control module will reference the heading angle As the desired yaw angle command, the rudder deflection is controlled via a PID algorithm, enabling the tiltable aircraft to fly along the reference heading. The speed control module maintains the preset cruise speed by adjusting the total thrust of the power source.

[0119] When a tilt-type aircraft is equipped with obstacle avoidance sensors, these sensors detect obstacles along the flight path in real time during cruise. If an obstacle is detected at a distance less than a safe threshold, the waypoint navigation module immediately generates a temporary detour waypoint, calculates the detour path, and controls the tilt-type aircraft to adjust its course to avoid the obstacle. Once the obstacle avoidance sensors no longer detect obstacles and the tilt-type aircraft returns to the extension of its original cruise path, the waypoint navigation module controls the tilt-type aircraft to return to the original cruise path and continue flying according to the preset waypoint sequence.

[0120] One-click return control supports both manual and automatic triggering modes to ensure the safe return of tiltable aircraft to the return reference point. The specific implementation is as follows:

[0121] The storage logic for the return reference point is as follows: When a tilt-type aircraft takes off, the GPS collects the coordinates of the takeoff point. The coordinates are stored in the PX4 flight control system's storage unit as the default return-to-home reference point; users can also send an "update return-to-home" command via the ground station to update the current position coordinates of the tiltable aircraft to a new return-to-home reference point.

[0122] The trigger conditions for one-click return to home include: the ground station sending a manual return-to-home command; the PX4 flight control system detecting that the remaining battery power is lower than a preset threshold; and the communication interruption between the PX4 flight control system and the ground station lasting longer than a preset time threshold.

[0123] After the return-to-home is triggered, the full-stage flight logic scheduling module switches to "return-to-home mode," and the waypoint navigation module sets the return-to-home reference point as the target waypoint and calculates the current position. Relative heading angle to the return reference point :

[0124]

[0125] The attitude control module controls the steering of the tiltable aircraft. During directional flight, the speed control module adjusts the flight speed to the return-to-home speed. When the GPS detects that the tiltable aircraft has reached the preset altitude above the return-to-home reference point, the full-stage flight logic scheduling module switches to "vertical landing mode" and completes a precise landing according to the vertical landing procedure.

[0126] The power source failure response control aims to ensure a safe emergency landing of a tiltable aircraft through mode switching and attitude control in the event of a failure of one or more power sources. The specific implementation is as follows:

[0127] The fault detection module monitors the operating status of the four power sources in real time. By collecting the speed feedback signals, current signals, and voltage signals of the power sources, it determines whether the power sources are in normal working condition. When a fault is detected in one or more power sources, the fault detection module immediately sends a fault signal to the full-stage flight logic scheduling module.

[0128] Upon receiving a fault signal, the full-stage flight logic scheduling module immediately triggers the "fault emergency mode" and sends a command to the tilt angle control module to quickly adjust the tilt angle of the remaining normal power sources to 90°, switching to fixed-wing flight mode. At this time, the total thrust is provided by the remaining normal power sources, and the thrust is redistributed through the power distribution module to ensure the power requirements for level flight.

[0129] The attitude control module switches to pure aerodynamic control surface logic, which controls the deflection angles of the ailerons, elevators, and rudder to achieve stable control of the roll, pitch, and yaw attitudes of the tilt-rotor aircraft.

[0130] Roll attitude control: by adjusting the aileron deflection angle This generates a rolling torque, which counteracts the attitude deviation caused by the faulty power source;

[0131] Pitch attitude control: by adjusting the elevator deflection angle This generates a pitching moment, maintaining the pitching attitude stability of the tiltable aircraft;

[0132] Yaw attitude control: by adjusting the rudder deflection angle This generates a yaw moment, correcting the heading deviation.

[0133] The speed control module gradually reduces the flight speed, while the waypoint navigation module guides the tilt-plane to the nearest flat area. When the flight speed drops to the preset gliding speed, the power distribution module gradually reduces the total thrust of the remaining power sources, allowing the tilt-plane to enter a gliding state and ultimately achieve an emergency landing by gliding, minimizing the risk of crash.

[0134] Example 2

[0135] In some optional implementations, this embodiment details the specific steps of an automatic control method for a four-powered tiltrotor aircraft during operation. It can be understood that this workflow, based on the control module and logic described in Embodiment 1, aims to achieve a complete operational process for the tiltrotor aircraft from startup to mission completion through fully autonomous flight phase scheduling. Specific steps are combined with... Figure 3 The operation flowchart shown is used for explanation.

[0136] Specifically, the workflow includes the following steps:

[0137] 1. System initialization and self-test

[0138] After the tilt-rotor aircraft is powered on, the PX4 flight control system first executes a hardware initialization procedure, including sensor calibration and communication link checks. The fault detection module monitors the status of the power source, servos, and sensors in real time. If the self-test passes, the system enters standby mode; otherwise, it reports an error and awaits processing. For example, the self-test process ensures that all components are in normal working order before flight, avoiding flight risks due to hardware failure.

[0139] 2. Vertical Takeoff Phase

[0140] Upon receiving the "vertical takeoff" command from the ground station, the full-stage flight logic scheduling module triggers the vertical takeoff mode. The tilt angle control module outputs control signals to lock the tilt angle of the four power sources at 0°, meaning the thrust direction is vertically upward. The power distribution module gradually increases the power source speeds from the lowest value to the hovering speed, while the attitude control module adjusts the speed difference based on IMU data to maintain the stability of the tiltable aircraft's attitude. During vertical takeoff, altitude control dynamically adjusts the reference speed using barometer data to ensure a smooth takeoff.

[0141] 3. Suspension stabilization stage

[0142] After vertical takeoff, the system automatically switches to hover mode. Maintaining a 0° roll angle, the position control module generates speed commands based on GPS coordinates and barometer altitude using dual-loop PID control, which are then converted into attitude corrections. Specifically, the attitude control module adjusts the power source speed difference to maintain stable roll, pitch, and yaw angles, while the altitude control module dynamically compensates for altitude deviations. The hover phase can be used to await mission instructions or conduct environmental observations.

[0143] 4. Horizontal takeoff transition phase

[0144] Upon receiving the "level takeoff" command or after achieving stable hovering, the full-stage flight logic scheduling module triggers the level takeoff mode. The tilt angle control module smoothly adjusts the power source tilt angle from 0° to 90° according to a preset curve. Simultaneously, the power distribution module increases the total thrust to balance the changes in the vertical lift component, ensuring the tiltable aircraft accelerates horizontally to cruise speed. Throughout the transition, the attitude control module, in conjunction with control surface control, suppresses attitude oscillations, achieving a seamless switch from multi-rotor mode to fixed-wing mode.

[0145] 5. Automatic cruise and waypoint navigation phase

[0146] Once in level flight, the system can perform automatic cruise. The waypoint navigation module analyzes the multi-waypoint path preset by the ground station, calculates the reference heading angle, and adjusts the rudder deflection via the attitude control module to ensure the tilt-plane aircraft flies in waypoint sequence. The speed control module maintains the preset cruise speed. If equipped with obstacle avoidance sensors, the system generates temporary waypoints when obstacles are detected, controlling the tilt-plane aircraft to avoid obstacles and return to the original path. This feature enhances environmental adaptability and is suitable for complex operational scenarios.

[0147] 6. Fixed-point level flight phase

[0148] During cruise, if hovering at a specific location or performing precise tasks is required, a fixed-point level flight mode can be triggered. The tilt angle is maintained at 90°, and the position control module compares the current coordinates with the target fixed-point coordinates, generating attitude angle commands through dual-loop PID control. The attitude control module adjusts the power source thrust and control surface deflection to maintain the stability of the tiltable aircraft at the target position. This stage is suitable for applications requiring precise positioning, such as surveying and surveillance.

[0149] 7. One-click return phase

[0150] Return-to-home (ROW) trigger conditions include manual command, low battery, or communication interruption. Upon triggering, the full-stage flight logic scheduling module switches to ROW mode, and the waypoint navigation module sets the ROW reference point as the target and calculates the relative heading angle. The tilt-adjustable aircraft flies towards the reference point, switching to vertical landing mode upon approach. During the ROW process, the speed control module reduces the flight speed to ensure stability, ultimately achieving a safe landing via vertical landing.

[0151] 8. Horizontal descent transition phase

[0152] Starting from level flight, the system executes the level descent procedure. The tilt angle control module smoothly adjusts the power source tilt angle from 90° to 0° according to the reverse curve, while the power distribution module reduces the total thrust, causing the tiltable aircraft to decelerate and switch to vertical landing mode. The attitude control module maintains attitude stability throughout the transition, avoiding abnormal altitude changes. When the tilt angle drops to 0° and the speed falls below the threshold, the system enters the vertical landing sub-procedure.

[0153] 9. Vertical Descent and Landing Phase

[0154] In vertical descent mode, the power distribution module gradually reduces the power source speed, while the altitude control module adjusts the descent rate based on barometer data. Upon detecting a ground contact signal, the system cuts off power to the power source, completing the landing. This process ensures a smooth and safe descent.

[0155] 10. Emergency Fault Handling Phase

[0156] If a power source failure is detected at any stage, the fault detection module immediately triggers the emergency mode. The tilt angle control module adjusts the tilt angle of the remaining normal power sources to 90°, switching to fixed-wing mode. The attitude control module maintains the flight attitude through pure control surfaces, the power distribution module redistributes thrust, and controls the tiltable aircraft to glide to a safe area for an emergency landing. This function significantly improves the system's fault tolerance and safety.

[0157] 11. Task completion and system shutdown

[0158] After completing the mission, the aircraft can tilt back to return to base and land. The system automatically executes shutdown procedures, including data saving and power-off of components. Users can check the mission status and perform subsequent analysis via the ground station.

[0159] The above steps fully cover the autonomous workflow of a four-power tilting aircraft. Through modular design and logical scheduling, it achieves smooth transition and stable control of various flight modes, demonstrating good feasibility and practicality. It can be widely applied in logistics, inspection, surveying and mapping and other fields.

[0160] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An automatic control method for a four-power-source tiltable aircraft, characterized in that, This method is based on the PX4 flight control system. The four-power-source tiltable aircraft includes four independently tiltable power sources and corresponding tilting actuators. The method includes: Step 1: Vertical Take-off and Landing Control: Controlling the tilt angle of the four power sources. Vertical takeoff or vertical landing can be achieved by adjusting the rotation speed of the four power sources, while maintaining the stability of the tiltable aircraft's attitude. Step 2, Suspension Attitude Control: In At the same time, based on the attitude, position and altitude data collected by the sensors, the required attitude correction amount is calculated, and the roll, pitch, yaw attitude, altitude and position stability of the tiltable aircraft is maintained by adjusting the speed difference of the four power sources. Step 3, Horizontal Takeoff Control: Starting from the hovering state, continuously adjust at a preset rate to ensure the tilt angle of the four power sources is changed without abrupt changes. Adjusting from 0° to 90° simultaneously increases the total thrust of the four power sources, enabling the tilt-type aircraft to accelerate horizontally to the preset cruise speed. Step 4, Fixed-point horizontal flight control: In In horizontal flight, the current coordinates are compared with the target fixed point coordinates, and the thrust of the power source and the control surfaces are adjusted to maintain the stability of the tiltable aircraft at the target fixed point position. Step 5, Horizontal Landing Control: Starting from horizontal flight, continuously adjust at a preset rate to ensure the tilt angle of the four power sources is changed without abrupt changes. Adjusting from 90° to 0° simultaneously reduces the total thrust of the four power sources, causing the tilting aircraft to decelerate and switch to vertical landing mode. Step Six: Fixed Angle Flight Control: Lock the user-defined fixed tilt angle. ,in and combined with this The dynamic vector is adjusted to regulate the speed difference between the four power sources in order to maintain the attitude stability of the tiltable aircraft. Step 7: Automatic Cruise Control: Analyze the preset multi-waypoint path and control the tilt-rotor aircraft in... In horizontal flight mode, fly in waypoint sequence; Step 8, One-click return control: Store the return reference point, and after triggering the return, control the tiltable aircraft to fly towards the return reference point. When the tiltable aircraft reaches the preset altitude and horizontal distance threshold above the return reference point, switch to landing mode to complete the return. Step Nine, Power Source Failure Response Control: When one or more power sources are detected to have failed, the tilt angle of the power sources that are not experiencing failure will be adjusted. Adjust to 90°, control the flight attitude through the control surfaces in fixed-wing mode, and perform a gliding emergency landing.

2. The automatic control method for a four-power-source tiltable aircraft according to claim 1, characterized in that, The PX4 flight control system includes: The tilt angle control module receives commands during the flight phase and outputs servo control signals to the tilt actuator to lock or adjust the tilt angle of the four power sources. ; The power distribution module is used to calculate the target rotational speed of each of the four power sources based on the flight phase and the output of the attitude controller; The full-stage flight logic scheduling module is used to trigger vertical takeoff and landing, hovering, horizontal takeoff, fixed-point horizontal flight, horizontal landing, fixed-angle flight, automatic cruise, and the one-key return control in step eight.

3. The automatic control method for a four-power-source tiltable aircraft according to claim 2, characterized in that, The tilt angle control module controls the tilt angle of the four power sources by receiving feedback signals from the servo motor of the tilt actuator. Closed-loop control is implemented to correct angle drift.

4. The automatic control method for a four-power-source tiltable aircraft according to claim 1, characterized in that, In step one, during vertical takeoff, the rotation speed of the four power sources is gradually increased from the lowest value to the hovering speed; during vertical landing, the rotation speed of the four power sources is gradually decreased from the hovering speed; when the PX4 flight control system detects a ground contact signal determined by data collected by the barometer and inertial measurement unit mounted on the tilt-rotor aircraft, it controls the power sources to cut off power. The barometer and inertial measurement unit are used to collect roll angle, pitch angle, yaw angle and three-axis angular velocity data of the tiltable aircraft.

5. The automatic control method for a four-power-source tiltable aircraft according to claim 1, characterized in that, In steps three and five, the tilt angle The adjustment rate is constant or varies according to a preset acceleration curve.

6. The automatic control method for a four-power-source tiltable aircraft according to claim 1, characterized in that, The triggering conditions for the one-key return-to-home control in step eight include: receiving a manual return-to-home command sent by the ground station, the PX4 flight control system detecting that the remaining battery power is lower than a preset threshold, or the communication interruption time between the PX4 flight control system and the ground station exceeds a preset time threshold.

7. The automatic control method for a four-power-source tiltable aircraft according to claim 1, characterized in that, In step seven, when the obstacle avoidance sensor of the tilt-mounted aircraft detects an obstacle, the waypoint navigation module generates a temporary detour waypoint, controls the tilt-mounted aircraft to fly along the temporary detour waypoint, and after avoiding the obstacle, controls the tilt-mounted aircraft to return to the next waypoint on the original cruise path.

8. The automatic control method for a four-power-source tiltable aircraft according to claim 2, characterized in that, The power distribution module is based on a fixed tilt angle. The total thrust Decomposed into vertical lift components With horizontal thrust component Based on the vertical lift and horizontal thrust requirements needed to maintain the tiltable aircraft's attitude stability, constant altitude, and target flight speed, the target rotational speed of the four power sources is calculated.

9. The automatic control method for a four-power-source tiltable aircraft according to claim 1, characterized in that, The data collected by the sensors in step two includes roll angle, pitch angle, yaw angle and three-axis angular velocity collected by the IMU inertial measurement unit, latitude and longitude coordinates collected by the GPS positioning module, and altitude data collected by the barometer.

10. The automatic control method for a four-power-source tiltable aircraft according to claim 1, characterized in that, In step nine, the roll, pitch, and yaw attitudes of the tilt-rotor aircraft are controlled by adjusting the deflection angles of the aileron servo, elevator servo, and rudder servo.

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