A distributed asynchronous tilt-rotor aircraft and control method

Abstract

The present invention relates to the field of aircraft technology, and discloses a distributed asynchronous tilt-rotor aircraft and a control method, comprising: receiving instructions from the ground to obtain ground instructions, obtaining position information, speed information and the health status of the aircraft; deciding the flight mode to be adopted; when in a multi-rotor mode, adopting an optimized cross-tilt angle to enhance the yaw control performance of the aircraft; when in a fixed-wing mode, providing an optimized control amount; when in a transition flight mode, obtaining corresponding control strategies based on different asynchronous tilt strategies for control; adjusting the aircraft attitude according to control instructions; being conducive to controlling different flight modes by adopting corresponding control allocation algorithms, being able to effectively solve the problems of complex control and low reliability encountered by the tilt-rotor aircraft during the transition process, realizing the flight capability of the tilt-rotor aircraft in the full angle of attack and full speed range during the transition process, and avoiding the aircraft from stalling during the transition process.

Description

Technical Field

[0001] The present invention relates to the field of aircraft technology, and more specifically to a distributed asynchronous tilt-rotor aircraft and a control method thereof. Background Art

[0002] A tilt-rotor aircraft is an aircraft that combines the characteristics of a helicopter and a fixed-wing aircraft. It has both a rotor and a fixed wing, and the rotor can be switched between a vertical position and a horizontal position. This aircraft has the advantages of both a helicopter's vertical / short takeoff and landing and a fixed-wing aircraft's high-speed cruise. It can take off and land in a small space or in places without sufficient runways, greatly improving its flexibility and adaptability. Through the tilt mechanism of the rotor shaft, the tilt-rotor aircraft can flexibly switch between helicopter mode (vertical takeoff and landing and hovering), transition mode (smooth transition from helicopter mode to fixed-wing mode), fixed-wing aircraft mode (high-speed cruise) and forward flight mode (long-distance flight), thereby combining the vertical take-off and landing capability of a helicopter and the high-speed cruise performance of a fixed-wing aircraft, providing the aircraft with great flexibility and a wide range of applications.

[0003] Tilt-rotor aircraft need to have the control capabilities of both helicopters and fixed-wing aircraft, and face complex control conversion and control redundancy problems during the transition process; tilt-rotor aircraft are very prone to accidents during the transition from vertical take-off and landing mode to horizontal flight mode, mainly due to power component failure and transition stall; in addition to component failure, gusts and control algorithms often cause transition stall; however, the current conventional tilt-rotor aircraft and control method design must ensure that the tilt transition process is completed within its transition corridor, and the aircraft's transition flight control is complex and easily affected by the environment, making it difficult to ensure the safety of the aircraft during the transition process.

[0004] In view of this, the present invention proposes a distributed asynchronous tilt-rotor aircraft and a control method. The distributed tilt-rotor multi-rotor aircraft has a high power redundancy. At the same time, the asynchronous tilt control technology can achieve flight capabilities at all angles of attack and speeds, providing higher reliability and stronger feasibility in tilt control, thereby significantly reducing the risk of accidents during the tilt transition stage. Summary of the invention

[0005] In order to overcome the above-mentioned defects of the prior art, the present invention provides a distributed asynchronous tilt-rotor aircraft and a control method to solve the problems existing in the above-mentioned background technology.

[0006] The present invention provides the following technical solution: a distributed asynchronous tilt-rotor aircraft and a control method, comprising the following steps:

[0007] Step S01: The aircraft flight control system receives the ground command and obtains the ground command, and obtains the position information and speed information through the aircraft's sensors and filtering algorithms; at the same time, the aircraft's health status is obtained based on the aircraft's components' health information;

[0008] Step S02: Combine the autopilot command preset by the flight control system with the ground command, the health status of the aircraft, and the position information and speed information of the aircraft to decide the flight mode to be adopted; if it is in the multi-rotor mode, execute step S03; if it is in the fixed-wing mode, execute step S04; if it is in the transition flight mode, execute step S05;

[0009] Step S03: When the aircraft is in the multi-rotor mode, the aircraft attitude is controlled by the speed difference of the power motor, and the yaw control performance of the aircraft is enhanced by using an optimized cross-tilt angle;

[0010] Step S04: When the aircraft is in fixed-wing mode, the control allocation algorithm gives an optimized control amount according to the flight speed and control efficiency;

[0011] Step S05: When the aircraft is in the transition flight mode, asynchronous tilting is used to complete the transition flight, and corresponding control strategies are obtained based on different asynchronous tilting strategies for control;

[0012] Step S06: The aircraft's actuator adjusts the aircraft's attitude according to the control command, and at the same time captures the flight status through the installed sensors, which are fed back to the flight control system after filtering and fusion, providing input data for the autopilot command and control allocation algorithm.

[0013] Preferably, the ground instructions include ground station instructions and remote control instructions, and the sensors include position sensors, inertial navigation sensors and other sensors, the position sensor includes a GPS sensor; the inertial navigation sensor includes a three-axis accelerometer and a three-axis gyroscope; the other sensors include a magnetometer, a pressure gauge and a laser ranging sensor.

[0014] Preferably, in the multi-rotor mode in step S03, all the tilt motors are controlled at a preset cross-tilt angle within the range of positive 85 degrees to positive 95 degrees; cross-tilt controls the tilt motor angle, and this mode is mainly for vertical take-off and landing flight. All ailerons will be controlled at negative 90 degrees, and the aircraft will achieve attitude control of yaw, pitch and roll through the speed difference of the power motors, and the altitude control of the aircraft is achieved by increasing or decreasing the common speed of all motors.

[0015] Preferably, in the fixed-wing mode in step S04, all the tilt motors are controlled at a tilt angle of 0 degrees. For pitch control, in this mode, the pitch of the aircraft is mainly controlled by the tilt motor angle and the aileron actuation. When flying at low speed, the tilt motor angle is controlled, and when flying at high speed, the aileron actuation is controlled. For yaw control, in this mode, the yaw of the aircraft is mainly controlled by the power motor speed and the rudder actuation. When flying at low speed, the speed difference of the power motors on the left and right sides is controlled, and when flying at high speed, the rudder actuation is controlled.

[0016] Preferably, in the transition flight mode in step S05, the aircraft will use asynchronous tilt to complete the transition flight; the asynchronous tilt will give priority to tilting the 4 tilt power systems in the middle of the front and rear ailerons; in this mode, the 4 peripheral tilt power systems are mainly responsible for the yaw control and roll control of the aircraft, and cooperate with the ailerons to support pitch moment balancing.

[0017] Preferably, the asynchronous tilting strategies in step S05 include two types, namely:

[0018] Strategy 1: First tilt the 4 tilt power systems between the front and rear ailerons. At this time, the control strategy of the control allocation algorithm is as follows:

[0019] Step a1: All ailerons return to the center;

[0020] Step b1: The four tilting power systems between the front and rear ailerons gradually tilt to about zero degrees, and the control allocation algorithm dynamically adjusts the speed and tilting rate of the eight power motors;

[0021] Step c1: As the flight speed increases, the lift provided by the wing continues to increase. When the lift provided by the wing reaches 50%, the remaining four tilting power systems are gradually tilted, and the control allocation algorithm dynamically adjusts the speed and tilting rate of the eight power motors.

[0022] Strategy 2: Tilt the two tilt power systems in the middle of the front aileron first; at this time, the control strategy of the control allocation algorithm is as follows:

[0023] Step a2: All ailerons return to the center;

[0024] Step b2: The two tilt power systems in the middle of the front aileron gradually tilt to zero degrees, controlling the upward deflection of the rear aileron, the downward deflection of the front aileron and the speed of the power motor to balance the additional torque generated during the tilting process; at the same time, the control allocation algorithm will dynamically adjust the speed and tilt rate of the four ailerons and eight power motors to cope with disturbances;

[0025] Step c2: As the flight speed increases, the lift provided by the wing increases continuously; when the lift provided by the wing reaches the first threshold, the two tilting power systems in the middle of the rear wing are gradually tilted, and the ailerons are gradually returned to the center; at the same time, the control allocation algorithm will dynamically adjust the speed and tilt rate of the four ailerons and eight power motors to cope with disturbances;

[0026] Step d2: When the lift provided by the wing further increases to the second threshold, the remaining four tilt power systems are gradually tilted. At the same time, the control allocation algorithm will dynamically adjust the speed and tilt rate of the eight power motors to cope with disturbances.

[0027] Preferably, the distributed asynchronous tilt-rotor aircraft includes a fuselage, a front wing, a rear wing and a vertical tail, and the distributed asynchronous tilt-rotor aircraft contains 8 sets of tilt power systems, each set of tilt power system is composed of a tilt motor, a power motor, a rotor and a connecting mechanism, the tilt power system is symmetrically installed on the leading edges of the front and rear wings, the rotor is installed on the output shaft of the power motor, the power motor is driven by the tilt motor through the connecting mechanism, and the power motor drives the rotor to rotate through the output shaft after receiving the command output by the flight control system; after receiving the command output by the flight control system, the tilt motor drives the power motor and the rotor through the connecting mechanism to realize tilt actuation, and the front and rear wings are arranged in a staggered manner, that is, the rear wing is higher than the front wing, the front and rear wings are provided with two pairs of ailerons, and the vertical tail is provided with a rudder.

[0028] Preferably, the actuators of the aircraft in step S06 include 8 tilt power systems, two pairs of ailerons and 1 rudder, and the controlled parameters include the rotation angles of 8 tilt motors and the rotation speeds of 8 power motors in the 8 tilt power systems, the actuation angles of 4 ailerons and the actuation angle of 1 rudder.

[0029] Preferably, the aircraft is in a multi-rotor mode during the vertical take-off and landing flight phase, in a fixed-wing mode during the cruising flight phase, and in a transition flight mode during the tilt-transition flight phase.

[0030] Technical effects and advantages of the present invention:

[0031] The present invention is provided with step S03, step S04 and step S05, which is conducive to controlling different flight modes by adopting corresponding control allocation algorithms, and can effectively solve the problems of complex control and low reliability encountered by the tilt-rotor aircraft in the transition process, and realize the flight capability of the tilt-rotor aircraft in the full angle of attack and full speed range in the transition process, and avoid the aircraft from stalling in the transition process; not only the influence of disturbance on the aircraft is taken into account, but also the control efficiency of the actuator under different flight states is included in the control allocation, thereby improving the safety and flight efficiency of the aircraft, and the flight performance is excellent. At the same time, there are many redundant actuators, and the control can be reconstructed through the control allocation algorithm when the power fails, and the reliability is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a flow chart of the distributed asynchronous tilt-rotor aircraft control method of the present invention.

[0033] Figure 2 The framework diagram of the distributed asynchronous tilt-rotor aircraft control method of the present invention is DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention. In addition, the forms of the various structures recorded in the following embodiments are merely illustrative. The distributed asynchronous tilt-rotor aircraft and control method involved in the present invention are not limited to the various structures recorded in the following embodiments. All other implementations obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0035] like Figure 1 As shown, the present invention provides a distributed asynchronous tilt-rotor aircraft and a control method, comprising the following steps:

[0036] Step S01: The aircraft flight control system receives instructions from the ground to obtain ground instructions, which include but are not limited to ground station instructions and remote control instructions, and obtains position information and speed information through various sensors and filtering algorithms of the aircraft; at the same time, the health status of the aircraft is obtained according to the health information of the aircraft components, such as judging whether the tilt motor, power motor, and rudder servo are failed through speed feedback;

[0037] The sensors include but are not limited to position sensors, inertial navigation sensors and other sensors. The position sensors include but are not limited to GPS sensors, which can obtain the longitude, latitude, altitude and other position information of the aircraft in real time and accurately, and are the basis of flight trajectory control; the inertial navigation sensors include but are not limited to three-axis accelerometers, three-axis gyroscopes, etc., which are used to measure the acceleration and angular velocity of the aircraft, and then calculate the speed and attitude information. The accelerometer can measure the linear acceleration of the center of mass of the aircraft, and the gyroscope can sense the angular velocity change of the aircraft; the other sensors include but are not limited to magnetometers, pressure gauges and laser ranging sensors, etc., which help improve the accuracy of position information and speed information;

[0038] Step S02: Combine the autopilot command preset by the flight control system with the ground command, the health status of the aircraft, and the position information and speed information of the aircraft to decide the flight mode to be adopted; if it is in the multi-rotor mode, execute step S03; if it is in the fixed-wing mode, execute step S04; if it is in the transition flight mode, execute step S05;

[0039] Step S03: When the aircraft is in the multi-rotor mode, the aircraft attitude is controlled by the speed difference of the power motor, and the yaw control performance of the aircraft is enhanced by using an optimized cross-tilt angle;

[0040] Step S04: When the aircraft is in fixed-wing mode, the control allocation algorithm gives the optimized control amount according to the flight speed and control efficiency; when flying at low speed, the pitch is mainly controlled by the tilt motor angle; when flying at high speed, it is mainly controlled by the aileron, and the yaw control is combined with the power motor and the rudder; at low speed, it is achieved by adjusting the speed difference of the power motor, and at high speed, it is mainly achieved by the deflection of the rudder; the roll control is mainly achieved by the deflection of the front aileron, and the rear aileron provides assistance when the torque is insufficient;

[0041] Step S05: When the aircraft is in the transition flight mode, asynchronous tilting is used to complete the transition flight, and corresponding control strategies are obtained based on different asynchronous tilting strategies for control; during the whole process, the control allocation algorithm adjusts the control amount of each actuator in real time according to the flight speed and control efficiency;

[0042] Step S06: The aircraft's actuator adjusts the aircraft's attitude according to the control command, and at the same time captures the flight status through the installed sensors, which are fed back to the flight control system after filtering and fusion, providing input data for the autopilot command and control allocation algorithm.

[0043] In this embodiment, it should be specifically explained that in step S03, step S04 and step S05, the flight control system generates expected instructions based on the autopilot instructions, and the control allocation algorithm calculates the optimized tilt motor angle, power motor speed and control instructions for rudder actuation based on the aircraft health status, flight status and the control efficiency of the actuator in this mode.

[0044] In this embodiment, it should be specifically explained that in the multi-rotor mode in step S03, all the tilt motors will be controlled at a preset cross-tilt angle within the range of positive 85 degrees to positive 95 degrees; the cross-tilt can significantly reduce the yaw throttle caused by installation errors and disturbances by controlling the tilt motor angle, improve the yaw control effect of the multi-rotor aircraft, and thus reduce the installation accuracy requirements of the rotor power system; since this mode is mainly for vertical take-off and landing flight, in order to reduce the vertical resistance, all ailerons will be controlled at about negative 90 degrees, and the aircraft will achieve yaw, pitch and roll attitude control through the speed difference of the power motor; the four sets of tilt power systems on the periphery of the aircraft have higher control efficiency due to their longer lever arms, so their tilt motors and power motors will be allocated more attitude control proportions; the altitude control of the aircraft is achieved by increasing or decreasing the common speed of all motors; in addition, the influence of external disturbances (such as gusts, vibrations, etc.) on the flight state will be adjusted by the control allocation algorithm to adjust the control amount of each actuator to achieve the purpose of anti-disturbance.

[0045] In this embodiment, it should be specifically explained that in the fixed-wing mode in step S04, all the tilt motors will be controlled at a tilt angle of about 0 degrees. At this time, the flight speed will greatly affect the control efficiency of each actuator, and thus affect the control allocation; for pitch control, in this mode, the pitch of the aircraft is mainly controlled by the tilt motor angle and aileron actuation. When flying at low speed, controlling the tilt motor angle is more efficient; and when flying at high speed, controlling the aileron actuation is more efficient; for yaw control, in this mode, the yaw of the aircraft is mainly controlled by the power motor speed and rudder actuation. When flying at low speed, controlling the speed difference of the power motors on the left and right sides is more efficient; and when flying at high speed, controlling the rudder actuation is more efficient; the roll of the aircraft will be achieved by aileron actuation, so the control allocation algorithm of the aircraft in this mode will give optimized control instructions for the tilt motor angle, power motor speed and rudder actuation according to the actuator efficiency and disturbance at different flight speeds.

[0046] In the present embodiment, it should be specifically explained that in the transition flight mode in step S05, the aircraft will use asynchronous tilt to complete the transition flight; because the four peripheral tilt power systems have longer lever arms and higher control efficiency for the aircraft attitude control, the asynchronous tilt will give priority to the four tilt power systems between the front and rear ailerons; in this mode, the four peripheral tilt power systems are mainly responsible for the yaw control and roll control of the aircraft, and cooperate with the ailerons to support pitch moment balancing. In theory, the asynchronous tilt strategy prevents the aircraft from stalling during the transition process, and the flight speed is controllable, thus achieving the flight capability of full angle of attack and full speed range.

[0047] In this embodiment, it should be specifically explained that the asynchronous tilting strategies in step S05 include two types, namely:

[0048] Strategy 1: First tilt the 4 tilt power systems between the front and rear ailerons. At this time, the control strategy of the control allocation algorithm is as follows:

[0049] Step a1: All ailerons return to the center;

[0050] Step b1: The four tilting power systems between the front and rear ailerons gradually tilt to about zero degrees, and the control allocation algorithm dynamically adjusts the speed and tilting rate of the eight power motors;

[0051] Step c1: As the flight speed increases, the lift provided by the wing continues to increase. When the lift provided by the wing reaches about 50%, the remaining four tilting power systems are gradually tilted, and the control allocation algorithm dynamically adjusts the speed and tilting rate of the eight power motors.

[0052] Strategy 2: Tilt the two tilt power systems in the middle of the front aileron first. This will introduce additional nose-down pitching moment, which can be balanced by aileron actuation. The control strategy of the control allocation algorithm is as follows:

[0053] Step a2: All ailerons return to the center;

[0054] Step b2: The two tilt power systems in the middle of the front aileron gradually tilt to about zero degrees, controlling the upward deflection of the rear aileron, the downward deflection of the front aileron and the speed of the power motor to balance the additional torque generated during the tilting process; at the same time, the control allocation algorithm will dynamically adjust the speed and tilt rate of the four ailerons and eight power motors to cope with disturbances;

[0055] Step c2: As the flight speed increases, the lift provided by the wing increases continuously; when the lift provided by the wing reaches the first threshold, the two tilting power systems in the middle of the rear wing are gradually tilted, and the ailerons are gradually returned to the center; at the same time, the control allocation algorithm will dynamically adjust the speed and tilt rate of the four ailerons and eight power motors to cope with disturbances;

[0056] Step d2: When the lift provided by the wing further increases to the second threshold, the remaining four tilting power systems are gradually tilted, and the control allocation algorithm dynamically adjusts the speed and tilting rate of the eight power motors to cope with disturbances;

[0057] The first threshold and the second threshold are set by those skilled in the art according to the actual situation of the aircraft, and this embodiment does not specifically limit their specific values.

[0058] In this embodiment, it should be specifically explained that the distributed asynchronous tilt-rotor aircraft includes a fuselage, a front wing, a rear wing and a vertical tail. The distributed asynchronous tilt-rotor aircraft includes 8 sets of tilt power systems, each of which is composed of a tilt motor, a power motor, a rotor and a connecting mechanism. The tilt power system is symmetrically installed on the leading edges of the front and rear wings, and the rotor is installed on the output shaft of the power motor. The power motor is driven by the tilt motor through the connecting mechanism. After the power motor receives the command output by the flight control system, it drives the rotor to rotate through the output shaft; after the tilt motor receives the command output by the flight control system, it drives the power motor and the rotor through the connecting mechanism to realize the tilt actuation. The front and rear wings are arranged in a staggered manner, that is, the rear wing is higher than the front wing, and the distance between the front and rear wings in the horizontal projection is widened to reduce the balancing resistance and the interference of the incoming flow, and improve the aerodynamic efficiency of the aircraft. The front and rear wings are provided with two pairs of ailerons, and the vertical tail is provided with a rudder. In different flight modes, the tilt power system can provide the aircraft with lift, thrust and the torque required to maintain the attitude.

[0059] In this embodiment, it should be specifically explained that the actuators of the aircraft in step S06 include 8 sets of tilt power systems, two pairs of ailerons and 1 rudder, and the controlled parameters include the rotation angles of 8 tilt motors and the speeds of 8 power motors in the 8 sets of tilt power systems, the actuation angles of 4 ailerons and the actuation angle of 1 rudder, a total of 21 control parameters; the same and symmetrical actuators use similar but fine-tuned control parameters to deal with interference;

[0060] The flight modes of the distributed asynchronous tilt-rotor aircraft include a multi-rotor mode, a transition flight mode and a fixed-wing mode.

[0061] In this embodiment, it should be specifically explained that during the vertical take-off and landing flight stage, the aircraft is in a multi-rotor mode, that is, the tilt motors of the 8 tilt power systems will be controlled at a tilt angle of about positive 90 degrees, the two pairs of ailerons will be controlled at an actuation angle of about negative 90 degrees, and the rudder will be controlled at about 0 degrees. Since the installation and design errors have a significant impact on the yaw control in actual engineering, a cross-tilt solution is adopted to determine the initial tilt angle of the tilt power system through an optimization algorithm. During this flight stage, the attitude control of the aircraft will be mainly or completely controlled by the 4 peripheral tilt power systems through Differential control is completed, that is, pitch control is achieved through the rotation speed of the power motors of the front and rear tilt power systems, roll control is achieved through the rotation speed of the power motors of the left and right tilt power systems, yaw control is achieved through the rotation speed of the power motors of the clockwise and counterclockwise tilt power systems, and altitude control is achieved through the speed changes of all power motors. The four inner tilt power systems participate in attitude control as little as possible because of their short lever arms and low control efficiency. When the four outer tilt power systems find it difficult to achieve the target aircraft attitude control, the four inner tilt power systems will intervene in the control, which is achieved by the control allocation algorithm;

[0062] During the cruise flight phase, the aircraft is in fixed-wing mode, that is, the tilt motors of the 8 tilt power systems will be controlled at a tilt angle of about 0 degrees. During this flight phase, the pitch control of the aircraft is achieved by the tilt motor and aileron actuation, and the control distribution of the tilt motor and aileron is determined based on the control efficiency and optimization algorithm; when the level flight speed is slow, the pitch control of the aircraft is mainly achieved by controlling the tilt motor angle of the aircraft's tilt power system. When the level flight speed is fast, the pitch of the aircraft is mainly achieved by the up and down deflection of the rear aileron. When the torque is insufficient, the front aileron can also be increased. The yaw control of the aircraft is achieved by the power motor and rudder actuation. The control distribution of the power motor and aileron is determined based on the control efficiency and optimization algorithm. When the level flight speed is slow, the yaw of the aircraft is achieved by controlling the symmetrical power motor speed difference. When the level flight speed is fast, the yaw of the aircraft is mainly achieved by the left and right deflection of the rudder. The roll of the aircraft is mainly achieved by the up and down deflection of the front aileron. When the torque is insufficient, the rear aileron can also be increased.

[0063] During the tilt transition flight phase, the aircraft is in a transition flight mode. At this time, the aircraft will use asynchronous tilting to complete the transition flight, that is, part of the tilt power system will first tilt to about 0 degrees to provide forward flight speed. As the wing lift continues to increase, the remaining tilt power system will be gradually tilted; during this flight phase, the pitch control of the aircraft is mainly achieved by controlling the actuation of the rear aileron and the speed difference of the power motors of the front and rear tilt power systems at about 90 degrees. The tilted power system supplements the torque by tilting up and down near 0 degrees to resist interference. The control amount is determined by the control allocation algorithm based on the flight speed and control efficiency; the yaw control of the aircraft is mainly achieved by controlling the actuation of the rudder and the speed difference of the tilted symmetrical power motors. At the same time, the tilt power system at about 90 degrees supplements the anti-interference ability of the yaw control by the cross-tilted tilt angle; the roll control of the aircraft is mainly achieved by controlling the actuation of the front aileron and the speed difference of the power motors of the left and right tilt power systems at about 90 degrees. The control amount is determined by the control allocation algorithm based on the flight speed and control efficiency.

[0064] In this embodiment, it should be specifically explained that the filtering algorithm can adopt Kalman filtering. Since sensor data is often affected by factors such as noise and error, it is necessary to process the data through the filtering algorithm to improve the accuracy and stability of the data. Kalman filtering is an optimal estimation algorithm based on a state space model. It realizes accurate estimation of the system state by predicting and correcting the system state. In the aircraft position solution, Kalman filtering can represent the position, speed and attitude of the aircraft as a state vector, and realizes optimal estimation of these information by predicting and correcting the state vector. According to the dynamic model of the system, the system state is predicted, the system state vector is predicted through the state transfer matrix to obtain a predicted state vector, and the covariance matrix of the predicted state vector is calculated to describe the uncertainty of the predicted state vector. According to the measurement data of the sensor, the predicted state vector is corrected, and the predicted state vector is compared with the sensor measurement data to obtain a correction vector. The covariance matrix of the correction vector is calculated to describe the uncertainty of the correction vector. By repeating the prediction and correction steps, the Kalman filter continuously updates the state vector, thereby realizing accurate estimation of the position, speed and attitude of the aircraft.

[0065] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0066] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A distributed asynchronous tilt-rotor aircraft and a control method, characterized in that: The following steps are involved: Step S01: The aircraft flight control system receives the ground command and obtains the ground command, and obtains the position information and speed information through the aircraft's sensors and filtering algorithms; at the same time, the aircraft's health status is obtained based on the aircraft's components' health information; Step S02: Combine the autopilot command preset by the flight control system with the ground command, the health status of the aircraft, and the position information and speed information of the aircraft to decide the flight mode to be adopted; if it is in the multi-rotor mode, execute step S03; if it is in the fixed-wing mode, execute step S04; if it is in the transition flight mode, execute step S05; Step S03: When the aircraft is in the multi-rotor mode, the aircraft attitude is controlled by the speed difference of the power motor, and the yaw control performance of the aircraft is enhanced by using an optimized cross-tilt angle; Step S04: When the aircraft is in fixed-wing mode, the control allocation algorithm gives an optimized control amount according to the flight speed and control efficiency; Step S05: When the aircraft is in the transition flight mode, asynchronous tilting is used to complete the transition flight, and corresponding control strategies are obtained based on different asynchronous tilting strategies for control; Step S06: The aircraft's actuator adjusts the aircraft's attitude according to the control command, and at the same time captures the flight status through the installed sensors, which are fed back to the flight control system after filtering and fusion, providing input data for the autopilot command and control allocation algorithm.

2. A distributed asynchronous tilt-rotor aircraft and control method according to claim 1, characterized in that: The ground instructions include ground station instructions and remote control instructions, and the sensors include position sensors, inertial navigation sensors and other sensors. The position sensor includes a GPS sensor; the inertial navigation sensor includes a three-axis accelerometer and a three-axis gyroscope; the other sensors include a magnetometer, a pressure gauge and a laser ranging sensor.

3. A distributed asynchronous tilt-rotor aircraft and control method according to claim 2, characterized in that: In the multi-rotor mode in step S03, all the tilt motors are controlled at a preset cross-tilt angle within the range of positive 85 degrees to positive 95 degrees; cross-tilt controls the tilt motor angle, and this mode is mainly for vertical take-off and landing flight. All ailerons will be controlled at negative 90 degrees, and the aircraft will achieve attitude control of yaw, pitch and roll through the speed difference of the power motors. The altitude control of the aircraft is achieved by increasing or decreasing the common speed of all motors.

4. A distributed asynchronous tilt-rotor aircraft and control method according to claim 3, characterized in that: In the fixed-wing mode in step S04, all the tilt motors are controlled at a tilt angle of 0 degrees. For pitch control, in this mode, the pitch of the aircraft is mainly controlled by the tilt motor angle and the aileron actuation. When flying at low speed, the tilt motor angle is controlled, and when flying at high speed, the aileron actuation is controlled. For yaw control, in this mode, the yaw of the aircraft is mainly controlled by the power motor speed and the rudder actuation. When flying at low speed, the speed difference of the power motors on the left and right sides is controlled, and when flying at high speed, the rudder actuation is controlled.

5. A distributed asynchronous tilt-rotor aircraft and control method according to claim 4, characterized in that: In the transition flight mode in step S05, the aircraft will use asynchronous tilt to complete the transition flight; the asynchronous tilt will give priority to tilting the 4 tilt power systems in the middle of the front and rear ailerons; in this mode, the 4 peripheral tilt power systems are mainly responsible for the yaw control and roll control of the aircraft, and cooperate with the ailerons to support pitch moment balancing.

6. A distributed asynchronous tilt-rotor aircraft and control method according to claim 5, characterized in that: The asynchronous tilting strategies in step S05 include two types, namely: Strategy 1: First tilt the 4 tilt power systems between the front and rear ailerons. At this time, the control strategy of the control allocation algorithm is as follows: Step a1: All ailerons return to the center; Step b1: The four tilting power systems between the front and rear ailerons gradually tilt to about zero degrees, and the control allocation algorithm dynamically adjusts the speed and tilting rate of the eight power motors; Step c1: As the flight speed increases, the lift provided by the wing continues to increase. When the lift provided by the wing reaches 50%, the remaining four tilting power systems are gradually tilted, and the control allocation algorithm dynamically adjusts the speed and tilting rate of the eight power motors. Strategy 2: Tilt the two tilt power systems in the middle of the front aileron first; at this time, the control strategy of the control allocation algorithm is as follows: Step a2: All ailerons return to the center; Step b2: The two tilt power systems in the middle of the front aileron gradually tilt to zero degrees, controlling the upward deflection of the rear aileron, the downward deflection of the front aileron and the speed of the power motor to balance the additional torque generated during the tilting process; at the same time, the control allocation algorithm will dynamically adjust the speed and tilt rate of the four ailerons and eight power motors to cope with disturbances; Step c2: As the flight speed increases, the lift provided by the wing increases continuously; when the lift provided by the wing reaches the first threshold, the two tilting power systems in the middle of the rear wing are gradually tilted, and the ailerons are gradually returned to the center; at the same time, the control allocation algorithm will dynamically adjust the speed and tilt rate of the four ailerons and eight power motors to cope with disturbances; Step d2: When the lift provided by the wing further increases to the second threshold, the remaining four tilt power systems are gradually tilted. At the same time, the control allocation algorithm will dynamically adjust the speed and tilt rate of the eight power motors to cope with disturbances.

7. A distributed asynchronous tilt-rotor aircraft and control method according to claim 6, characterized in that: The distributed asynchronous tilt-rotor aircraft comprises a fuselage, a front wing, a rear wing and a vertical tail. The distributed asynchronous tilt-rotor aircraft includes 8 sets of tilt-rotor power systems, each of which is composed of a tilt-rotor motor, a power motor, a rotor and a connecting mechanism. The tilt-rotor power systems are symmetrically installed on the leading edges of the front and rear wings, and the rotor is installed on the output shaft of the power motor. The power motor is driven by the tilt-rotor motor through the connecting mechanism. After receiving the command output by the flight control system, the power motor drives the rotor to rotate through the output shaft; after receiving the command output by the flight control system, the tilt-rotor motor drives the power motor and the rotor through the connecting mechanism to realize tilt actuation. The front and rear wings are arranged in a staggered manner, that is, the rear wing is higher than the front wing, the front and rear wings are provided with two pairs of ailerons, and the vertical tail is provided with a rudder.

8. A distributed asynchronous tilt-rotor aircraft and control method according to claim 7, characterized in that: In step S06, the actuators of the aircraft include 8 tilt power systems, two pairs of ailerons and 1 rudder, and the controlled parameters include the rotation angles of 8 tilt motors and the rotation speeds of 8 power motors in the 8 tilt power systems, the actuation angles of 4 ailerons and the actuation angle of 1 rudder.

9. A distributed asynchronous tilt-rotor aircraft and control method according to claim 8, characterized in that: The aircraft is in a multi-rotor mode during the vertical take-off and landing flight phase, in a fixed-wing mode during the cruising flight phase, and in a transition flight mode during the tilt transition flight phase.

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