CN110901916B

CN110901916B - Aircraft and flight control method and device thereof

Info

Publication number: CN110901916B
Application number: CN201911232730.3A
Authority: CN
Inventors: 艾田付; 徐彬; 项昌乐; 樊伟; 张一博; 邢志强
Original assignee: Beijing Institute of Technology BIT; Chongqing Innovation Center of Beijing University of Technology
Current assignee: Beijing Institute of Technology BIT; Chongqing Innovation Center of Beijing University of Technology
Priority date: 2019-12-05
Filing date: 2019-12-05
Publication date: 2022-10-14
Anticipated expiration: 2039-12-05
Also published as: CN110901916A

Abstract

The invention relates to an aircraft and a flight control method and device thereof, compared with an open rotor type aircraft, the ducted aircraft can meet the requirement of high-altitude approach flight, compared with the prior scheme, the ducted aircraft researches the relationship between the wall effect generated when the aircraft approaches the wall surface and the distance between the aircraft and the wall surface, takes the influence brought by the wall effect into the construction of an aircraft model, obtains the relationship between the distance between the aircraft and the wall surface and the system stability through analysis, and further converts the relationship into the minimum safe distance allowed to approach, namely the minimum safe distance between the aircraft and the wall surface under the condition of complete machine system stability, and carries out flight control on the aircraft based on the minimum safe distance obtained by considering the wall effect, obviously, the stability and the safety of the aircraft during approach wall surface flight (mainly refers to the working condition that the approach wall surface is suspended to execute operation) can be improved.

Description

Aircraft and flight control method and device thereof

Technical Field

The application belongs to the technical field of air approach operation and flight control, and particularly relates to an aircraft and a flight control method and device thereof.

Background

As an aircraft, research related to unmanned aerial vehicles has become a research hotspot in today's society. Among them, it is the future development trend to utilize aerial unmanned aerial vehicle and relevant equipment to replace the people to carry out aerial job task. Aerial unmanned aerial vehicle carries on operation equipment and replaces the people to accomplish aerial operation task, can reduce economic cost, reduce intensity of labour and reduce the safety risk of carrying out work task.

In future aerial operation, the unmanned aerial vehicle is required to be capable of performing remote photographing, reconnaissance and other operations, and also required to meet requirements for repairing high-altitude equipment or performing high-altitude rescue and the like, and the requirements for the unmanned aerial vehicle to be close to a wall surface or perform interactive contact operation with the environment can be met, so that the unmanned aerial vehicle can safely fly close to the wall surface (mainly referring to a working condition that the unmanned aerial vehicle is suspended close to the wall surface to perform operation) and is a prerequisite basis for achieving the contact operation of the unmanned aerial vehicle and the wall surface.

Most of the existing unmanned aerial vehicles cannot fly close to the wall surface, if the existing mainstream unmanned aerial vehicle is mostly of an open rotor type, the unmanned aerial vehicle of the open rotor type structure generally can be far away from various wall surfaces in the environment when working, and generally cannot be competent when flying in a compact and complex environment or needing to be close to the wall surface for operation; however, a few studies on the approach wall surface by the unmanned aerial vehicle only generally use the aerodynamic effect between the unmanned aerial vehicle and the wall surface, that is, the wall surface effect, as an external disturbance, and utilize a related control algorithm to eliminate adverse effects caused by the disturbance as much as possible, for example, the unmanned aerial vehicle attitude can be suspended stably through estimating the disturbance magnitude by the adaptive neural network algorithm and adjusting the control law of the controller, so as to maintain the stability of the operation of the unmanned aerial vehicle on the approach wall surface. However, this has only carried out certain compensation to the aerodynamic effect between unmanned aerial vehicle and the wall from compensating external disturbance angle, is difficult to eliminate the adverse effect that the disturbance brought completely, especially when unmanned aerial vehicle and wall apart from very little, and these interferences still can influence unmanned aerial vehicle's working property to stability when being difficult to guarantee unmanned aerial vehicle to the wall completely, the corresponding unmanned aerial vehicle that leads to still has the potential safety hazard when being close the operation of wall.

From this, aircrafts such as current unmanned aerial vehicle can not approach the wall surface to fly, or only compensate as an external disturbance simply the wall surface effect that unmanned aerial vehicle and wall surface produced, are difficult to guarantee the stability of unmanned aerial vehicle when approaching the wall surface to a higher degree, still have the potential safety hazard.

Disclosure of Invention

In view of this, an object of the present application is to provide an aircraft and a flight control method and apparatus thereof, where the influence of a wall effect on a whole machine model is taken into consideration to incorporate the wall effect into the construction of an aircraft model, so as to determine a minimum safe distance between the aircraft and a wall surface on the premise of a complete machine system being stable, and finally, stability and safety performance of the aircraft when approaching the wall surface in the air are guaranteed based on the minimum safe distance.

A flight control method of an aircraft, wherein the aircraft is a ducted aircraft; the method comprises the following steps:

determining the association relation between the resultant force vector and resultant moment vector of the aircraft and the distance from the aircraft to the wall surface under the wall surface effect;

constructing a first dynamic model of the aircraft in the presence of wall effect based on the incidence relation; the first dynamic model comprises the resultant force vector and the resultant moment vector expressed based on the distance;

determining a first space state equation when the aircraft has a wall effect based on the first dynamic model; the system matrix and the control matrix of the first space state equation comprise the distance;

constructing a first closed loop system when the aircraft has a wall effect by using a given target feedback controller and a system matrix and a control matrix of the first space state equation; the target feedback controller is a feedback controller which can enable the second closed-loop system to maintain stable when the aircraft has no wall surface effect;

determining the minimum value of the distance which can enable the first closed loop system to maintain stable, and obtaining the minimum safe distance from the aircraft to the wall surface;

controlling the flight of the aircraft based on the minimum safe distance.

In the above method, preferably, the distance from the aircraft to the wall surface is the distance d from the center of the rotor of the aircraft to the wall surface _WE The resultant force vector comprises: the total system lift vector and the gravity vector of the aircraft under the wall effect hovering working condition; the resultant torque vector includes: the reaction torque vector and the tilting torque vector of the aircraft under the wall effect hovering working condition;

the determining of the association relationship between the resultant force vector and the resultant moment vector of the aircraft and the distance from the aircraft to the wall surface under the wall surface effect includes:

determining a system total lift vector to distance ratio d for an aircraft _WE The association relationship between/R;

determining a reactive torque vector to distance ratio d for an aircraft _WE The association relationship between/R;

determining a tilting moment vector to distance ratio d of an aircraft _WE The association relationship between/R;

based on the ratio d of the total lift force vector, the reaction torque vector and the tilting torque vector of the system to the distance respectively _WE Determining the correlation between the total lift vector, the reaction torque vector and the tilting torque vector of the system and the distance d _WE The incidence relation between the two;

wherein the distance ratio d _WE the/R is the distance d from the center of the rotor wing of the aircraft to the wall surface _WE To the aircraft propeller radius R.

The above method, preferably, before the building the first dynamic model of the aircraft with the wall effect based on the correlation, further includes:

constructing a second dynamic model when the aircraft has no wall effect; the inputs to the second dynamical model include a resultant force vector F to which the aircraft is subjected excluding gravity _b Aerodynamic moment vector M to which the aircraft as a whole is subjected _b And aircraft gravity F _g The output comprises a linear velocity vector, an angular velocity vector and an Euler angle vector of the aircraft body, and the total system lift vector of the aircraft is the sumExternal force vector F _b Component force in Z-axis direction of the aircraft body, and reaction torque vector of the aircraft is aerodynamic moment vector M _b The amount of moment about the Z axis.

In the above method, preferably, the building a first dynamic model of the aircraft with a wall effect based on the correlation includes:

determining a correction factor alpha for correcting the total lift vector of the system and a correction factor beta for correcting the reaction torque vector based on the incidence relation, and determining an expression of the tilting torque vector; the expressions of the correction factors alpha and beta and the tilting moment vector include the distance d _WE ；

Using the correction factor alpha to the resultant external force vector F in the second dynamic model _b Correcting component force in the Z-axis direction of the machine body; using the correction factor beta to the aerodynamic moment vector M in the second dynamic model _b Correcting the moment around the Z axis; and introducing the tilting moment vector into the input of the second dynamic model to obtain the first dynamic model when the aircraft has the wall effect.

In the above method, preferably, the first kinetic model is a nonlinear system; the determining a first spatial equation of state for the aircraft with the wall effect based on the first dynamical model includes:

linearizing the first kinetic model into a linear system at a system equilibrium point of the first kinetic model;

and determining a state space equation corresponding to the linear system after the first dynamic model is linearized based on a preset identification technology to obtain a first state space equation when the aircraft has a wall effect.

In the above method, preferably, the second kinetic model is a nonlinear system; the method for constructing the first closed-loop system when the aircraft has the wall effect by using a given target feedback controller and the system matrix and the control matrix of the first space state equation comprises the following steps:

linearizing the second kinetic model into a linear system at a system balance point of the second kinetic model;

determining a state space equation corresponding to the linear system after the second dynamic model is linearized based on a preset identification technology to obtain a second state space equation when the aircraft has no wall surface effect;

determining a second closed loop system of the aircraft without the wall effect based on the second state space equation;

determining a target feedback controller capable of maintaining the second closed loop system stable when the aircraft has no wall effect;

and constructing a first closed loop system when the aircraft has the wall effect by using the target feedback controller and the system matrix and the control matrix of the first space state equation.

A flight control device of an aircraft, wherein the aircraft is a ducted aircraft; the device comprises:

the first determining unit is used for determining the association relationship between the resultant force vector and the resultant moment vector of the aircraft and the distance between the aircraft and the wall surface under the wall surface effect;

the first construction unit is used for constructing a first dynamic model when the aircraft has the wall effect based on the incidence relation; the first dynamic model comprises the resultant force vector and the resultant moment vector expressed based on the distance;

the second determination unit is used for determining a first space state equation when the aircraft has the wall effect based on the first dynamic model; the system matrix and the control matrix of the first space state equation comprise the distance;

the second construction unit is used for constructing a first closed-loop system when the aircraft has the wall effect by utilizing a given target feedback controller and a system matrix and a control matrix of the first space state equation; the target feedback controller is a feedback controller which can enable the second closed-loop system to maintain stable when the aircraft has no wall effect;

a third determining unit, configured to determine a minimum value of the distance that enables the first closed-loop system to maintain stable, so as to obtain a minimum safe distance from the aircraft to the wall surface;

a control unit for controlling the flight of the aircraft based on the minimum safe distance.

The above device is preferably arranged such that the distance from the aircraft to the wall surface is the distance d from the center of the rotor of the aircraft to the wall surface _WE Said resultant force vector comprising: the total system lift vector and the gravity vector of the aircraft under the wall effect hovering working condition; the resultant torque vector includes: the reaction torque vector and the tilting torque vector of the aircraft under the wall effect hovering working condition;

the first determining unit is specifically configured to:

determining a reactive torque vector to distance ratio d for an aircraft _WE The incidence relation between the/Rs;

determining a tilting moment vector to distance ratio d of an aircraft _WE The incidence relation between the/Rs;

based on the ratio d of the total lift force vector, the reaction torque vector and the tilting torque vector of the system to the distance _WE Determining the correlation between the total lift vector, the reaction torque vector and the tilting torque vector of the system and the distance d _WE The incidence relation between the two;

The above apparatus, preferably, further comprises:

the third construction unit is used for constructing a second dynamic model when the aircraft has no wall effect before the first construction unit constructs the first dynamic model when the aircraft has the wall effect based on the incidence relation; the inputs to the second dynamical model include a resultant force vector F to which the aircraft is subjected excluding gravity _b Aerodynamic moment vector M to which the aircraft as a whole is subjected _b And aircraft gravity F _g The output includes linear velocity vector, angular velocity vector and Euler angle vector of aircraft body, and the flight is carried outThe system total lift vector of the device is the resultant external force vector F _b Component force in the Z-axis direction of the body, and the reaction torque vector of the aircraft is the aerodynamic moment vector M _b An amount of moment about the Z-axis.

The above apparatus, preferably, the first building unit is specifically configured to:

determining a correction factor alpha for correcting the total lift vector of the system and a correction factor beta for correcting the reaction torque vector based on the incidence relation, and determining an expression of the tilting moment vector; the distance d is included in the expressions of the correction factors alpha and beta and the tilting moment vector _WE ；

Using the correction factor alpha to the resultant force vector F in the second dynamic model _b Correcting component force in the Z-axis direction of the machine body; using the correction factor beta to the aerodynamic moment vector M in the second dynamic model _b Correcting the moment around the Z axis; and introducing the tilting moment into the input of the second dynamic model to obtain the first dynamic model when the aircraft has the wall effect.

In the above apparatus, preferably, the first kinetic model and the second kinetic model are respectively a nonlinear system;

the second determining unit is specifically configured to:

determining a state space equation corresponding to the linear system after the first dynamic model is linearized based on a preset identification technology to obtain a first state space equation when the aircraft has a wall effect;

the second building unit is specifically configured to:

determining a second closed-loop system of the aircraft without the wall effect based on the second state space equation;

An aircraft, comprising: a fuselage and at least two ducted propeller systems;

further comprising:

a controller for flight controlling the aircraft based on the minimum safe distance in the flight control method as described above; alternatively, an external control signal is received and the flight control of the aircraft is performed based on the control signal, which is a signal generated based on the minimum safe distance in the flight control method as described above.

According to the scheme, the ducted aircraft can meet the requirement of high-altitude approaching flight compared with an open rotor aircraft, and compared with the existing scheme, the ducted aircraft researches the relationship between the wall effect generated when the aircraft approaches the wall surface and the distance between the aircraft and the wall surface, considers the influence brought by the wall effect into the construction of an aircraft model, obtains the relationship between the distance between the aircraft and the wall surface and the system stability through analysis, and further converts the relationship into the minimum safe distance allowed to approach, namely the minimum safe distance between the aircraft and the wall surface under the condition that the whole system is stable, performs flight control on the aircraft based on the minimum safe distance obtained by considering the wall effect, and obviously improves the stability and safety when the aircraft flies near the wall surface (mainly refers to the working condition that the aircraft hovers near the wall surface to execute operation).

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a coaxial counter-rotor double-duct unmanned aerial vehicle provided in an alternative embodiment of the present application;

FIG. 2 is a schematic flow chart diagram of a method for flight control of an aircraft according to an alternative embodiment of the present application;

fig. 3 is a schematic view of wall effect streamlines of a ducted drone provided in an alternative embodiment of the present application;

FIG. 4 (a) is a schematic view of the total lift at different distance ratios provided by an alternative embodiment of the present application;

FIG. 4 (b) is a schematic illustration of the reaction torque at different distance ratios as provided by an alternative embodiment of the present application;

FIG. 4 (c) is a schematic illustration of the tilting moment at different distance ratios provided by the alternative embodiment of the present application;

fig. 5 is a view of a dynamic model structure of the ducted unmanned aerial vehicle provided in the alternative embodiment of the present application when no wall effect is considered;

fig. 6 is a view of a dynamic model structure of the ducted unmanned aerial vehicle provided in the alternative embodiment of the present application, in consideration of a wall effect;

FIG. 7 is a schematic representation of one configuration of a flight control apparatus for an aircraft according to an alternative embodiment of the present application;

FIG. 8 is a schematic representation of another configuration of a flight control apparatus for an aircraft according to an alternative embodiment of the present application;

FIG. 9 is a schematic structural diagram of an aircraft according to an alternative embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort belong to the protection scope of the present application.

The application discloses an aircraft and a flight control method and device thereof, wherein the wall effect is brought into the construction of an aircraft model by considering the influence of the wall effect on the whole aircraft model, the minimum safety distance between the aircraft and the wall surface under the premise of the stability of the whole system is determined, and finally the stability and the safety performance of the aircraft when approaching the wall surface in the air are guaranteed based on the minimum safety distance.

In this application the aircraft mainly indicates to carry on the unmanned aerial vehicle that the operation equipment substitute people got to accomplish aerial operation task, and at present, the unmanned aerial vehicle structural style of mainstream is open rotor formula mostly, and various walls in the environment can be kept away from to open rotor structure unmanned aerial vehicle during operation generally, when flying or need be approached the wall and carry out the operation under the environment compact in space and complicated, generally can not be competent. Ducted drones can work in more hazardous, complex, and unknown environments than open rotor drones. Due to the existence of the duct, the internal paddle can be prevented from being in direct contact with the outside, and when an accident happens, the paddle cannot be directly ejected to people, so that the safety performance of the paddle is higher. In addition, due to the effect of the airflow in the duct lip, the ducted drone generates more thrust than an open rotor drone at the same blade size. And the ducted unmanned aerial work platform can replace human to carry out work tasks in complex and narrow environments due to the characteristics of compact structure, large load and high safety.

In view of duct formula unmanned aerial vehicle's above-mentioned advantage, this application mainly is directed against duct formula unmanned aerial vehicle, researches its safe flight scope that can ensure system stability, security under the wall effect influences, and then carries out flight control to it.

Alternatively, the ducted drone may be a coaxial counter-oar dual ducted drone, the wall which approaches when performing aerial work being generally a vertical wall or wall. For the convenience of understanding, the following first briefly describes the components and functions of the components of the coaxial counter-rotating double-duct unmanned aerial vehicle.

As shown in fig. 1, the coaxial contra-rotor dual-ducted drone is mainly composed of two ducted propeller systems 101 and a fuselage 102. The two ducted propeller systems 101 are arranged in a longitudinal row and symmetrically arranged on two sides of the fuselage 102. Set up two structures, the same and coaxial screw that sets up of size in duct screw system 101: an upper paddle and a lower paddle. The rotating directions of the upper paddle and the lower paddle are opposite, and unbalanced moment generated in the rotating process can be mutually offset. The ducted propeller system 101 is further provided with a driving motor, the propeller is connected with the motor, rotating power is output through the motor, and the motor support 103 is used for fixing the motor. A battery, a flight control system, and the like are provided in the body 102. A control rudder 104 is fixedly connected below each of the two ducts, and the control rudder 104 has an aerodynamic control surface for generating a control torque in the roll direction. The lift force of the whole double-duct unmanned aerial vehicle is provided by four propellers in the front duct and the rear duct, pitching and yawing moments are provided by the speed difference between the propellers in the front duct and the rear duct, the pitching channel of the pitching direction is generated by the rotating speed difference of the propellers in the front duct and the rear duct to control the body, the rolling channel of the body is controlled by the moment of the rolling direction generated by the deflection of the control surface, the yawing channel of the body is controlled by the torque difference generated by the rotation directions of the upper propeller and the lower propeller in each duct in the opposite directions, and the attitude control of the body is realized. In addition, landing gear 105 may be included.

Referring to fig. 1, when the ducted drone flies close to a wall surface, an operation executing component is generally in the middle of the fuselage, so that the duct generally faces the wall surface in the Y-axis direction or the negative Y-axis direction.

This application is mainly to foretell duct formula unmanned aerial vehicle, the research is under the flight operating mode of hovering, when receiving the influence of wall effect, unmanned aerial vehicle is to the distance of wall and the stable relation of system self, and then on this basis, in the construction of incorporating the aircraft model with the wall effect, confirm the minimum safe distance between unmanned aerial vehicle and the wall under the stable prerequisite of complete machine system, and then reach the safe flight control that carries on to unmanned aerial vehicle, guarantee unmanned aerial vehicle stability and the purpose of security when approaching the wall operation.

Referring to fig. 2, a schematic flow chart of a flight control method of an aircraft provided by the present application for a ducted unmanned aerial vehicle is shown in fig. 2, where the flight control method may include the following processing procedures:

step 201, determining the association relationship between the resultant force vector and resultant moment vector of the aircraft under the wall effect and the distance from the aircraft to the wall surface.

The inventor finds that, when the coaxial contra-propeller ducted unmanned aerial vehicle is suspended close to a vertical wall, the wall can prevent free movement of air, so that the airflow at a duct lip close to one side of the wall is decelerated, the static pressure at the duct lip is increased, an unbalanced moment is finally formed, the duct lip is driven to tilt towards one side of the vertical wall, and a wall effect streamline is shown in fig. 3, wherein 301 represents a wall, 302 represents a duct wall, 303 represents an upper propeller blade, 304 represents a lower propeller blade, and 305 represents a duct wall. Form unbalanced moment is promptly for the moment of verting, because can seriously influence duct formula unmanned aerial vehicle's stability when this moment is too big, makes unmanned aerial vehicle vert to the wall, and then leads to very obvious "bumping the wall phenomenon", therefore it can't ignore in the analysis of the influence that the wall effect brought the complete machine.

Therefore, in the embodiment of the application, when the first dynamic model in the wall effect is constructed and the aircraft is subjected to flight control based on the model, the consideration of the tilting moment vector of the aircraft in the wall effect hovering working condition can be taken into consideration, and in addition, the factors such as the total lift vector and the gravity vector of the system of the aircraft in the wall effect hovering working condition, the reaction torque vector of the aircraft in the wall effect hovering working condition and the like can be considered.

Thus, in this step 201, the resultant force vector may include, but is not limited to: the total lift vector and the gravity vector of the system when the aircraft is in the wall effect hovering working condition; the resultant torque vector may include, but is not limited to: the reaction torque vector and the tilting torque vector of the aircraft under the wall effect hovering working condition. In addition, the present inventionThe embodiment specifically adopts the distance d from the center of a rotor wing of the aircraft to the wall surface _WE To indicate the distance of the aircraft to the wall.

The inventor analyzes the current d through CFD (computational fluid Dynamics) simulation experiments _WE Data of total tension vector, reaction torque vector and tilting torque vector of unmanned aerial vehicle system when/R is different ratios, wherein d _WE The distance from the center of the rotor wing of the unmanned aerial vehicle to the vertical wall surface, R is the radius of the propeller, and the ratio d between the total lift vector, the reactive torque vector and the tilting torque vector of the system of the aircraft and the distance is obtained _WE The incidence relation among the vectors, the reaction torque vector and the tilting moment vector of the system obtained in a simulation experiment are respectively compared with the distance d _WE The relationship between/R can be seen in FIG. 4 (a), FIG. 4 (b), and FIG. 4 (c), respectively.

On this basis, convertible different distances d that obtain duct formula unmanned aerial vehicle to wall _WE And fitting the data of the total lift vector, the reactive torque vector and the tilting torque vector of the unmanned aerial vehicle system by a least square method to obtain the correlation expressions of the distance from the unmanned aerial vehicle to the wall surface and the total lift vector, the reactive torque vector and the tilting torque vector of the system.

Step 202, constructing a first dynamic model of the aircraft with wall effect based on the incidence relation; the first kinetic model includes the resultant force vector and the resultant moment vector expressed based on the distance.

In the embodiment of the present application, the first dynamic model in the presence of the wall effect is a model that is constructed on the basis of the second dynamic model in the absence of the wall effect, so that the second dynamic model in the absence of the wall effect of the aircraft can be constructed in advance before the first dynamic model in the absence of the wall effect.

Under the condition of not considering the wall effect, a system model equation of the double-duct unmanned aerial vehicle, namely a second dynamic model without the wall effect can be deduced according to the leaf element theory and the momentum theory, and a dynamic model structure diagram of the system without the wall effect is established, wherein the dynamic model structure diagram is used for the dynamic modelThe structural diagram can be specifically referred to FIG. 5, wherein u _col ，u _lat ，u _lon And u _ped Respectively representing the normalized control quantities of the throttle (height), the transverse (roll), the longitudinal (pitch) and the heading (yaw) channels. After the corresponding actuating mechanism of the unmanned aerial vehicle inputs the quantities, the output is the rotor rotation speed and the control surface angle of the ducted system, and based on the rotor rotation speed and the control surface angle, the coaxial counter-propeller system can generate a corresponding resultant external force vector F _b And a pneumatic moment vector M _b Wherein, F _b Specifically representing the resultant external force vector, M, of the unmanned aerial vehicle except gravity _b Specifically, the aerodynamic moment vector that unmanned aerial vehicle whole received.

Resultant force vector F from system _b Pneumatic moment vector M _b And aircraft gravity F _g And deriving a nonlinear dynamical equation of the system by using a Newton Euler equation so as to obtain a nonlinear dynamical system, wherein the system is also a second dynamical model of the unmanned aerial vehicle without the wall effect. Wherein the inputs to the second dynamical model include a resultant force vector F to which the aircraft is subjected excluding gravity _b Aerodynamic moment vector M to which the aircraft as a whole is subjected _b And aircraft gravity F _g The output comprises three direction linear velocity vectors (u, v, w) of the unmanned plane body ^T Three directional angular velocity vectors of body (p, q, r) ^T And Euler angle vector (phi, theta, psi) of body ^T 。

It should be noted that the total lift vector of the system of the unmanned aerial vehicle is the resultant external force vector F _b Component force in Z-axis direction of the body, and reaction torque vector is the aerodynamic moment vector M _b The amount of moment about the Z axis.

On the basis, a first dynamic model of the aircraft with wall effect is constructed, and the first dynamic model can be realized through the following processing procedures:

1) Determining a correction factor alpha for correcting the total lift vector of the system and a correction factor beta for correcting the reaction torque vector based on the incidence relation, and determining an expression of the tilting torque vector;

when no wall surface exists around the unmanned aerial vehicle, the duct does not have the wall surface effect, which is equal to that when the system is modeled, because the distance between the duct wall surface and the wall surface is far enough, the influence caused by the wall surface effect is very small, the influence can be ignored and is not included in the model, and when the constraint environment exists, the influence caused by the wall surface effect needs to be considered together when modeling.

In consideration of the influence caused by the wall effect, the embodiment specifically corrects the total lift vector and the reactive torque vector of the system in the unconstrained environment, that is, corrects the total lift vector and the reactive torque vector of the system in the second dynamic model in the unconstrained environment, so that the influence caused by the wall effect is incorporated into the construction of the whole model of the unmanned aerial vehicle. In order to correct the total lift vector and the reaction torque vector of the system, correction factors of force and moment are determined respectively.

The correction factor alpha for correcting the total lift vector of the system when the system has wall effect and the distance ratio d _WE The relation/R can be obtained based on the ratio of the total lift vector of the system under different distance ratios (with wall effect) to the total lift vector of the system under the unconstrained environment, and the correction factor beta for correcting the counter torque vector when the system has the wall effect is similar to alpha and can be obtained based on the ratio of the counter torque vector of the system under different distance ratios (with wall effect) to the counter torque vector of the system under the unconstrained environment. At the same time, tilting moment vector M _y And also has a certain relation with the distance ratio, which can be expressed by the distance ratio.

3) Using the correction factor alpha to the resultant external force vector F in the second dynamic model _b Correcting component force in the Z-axis direction of the machine body; using the correction factor beta to the aerodynamic moment vector M in the second dynamic model _b Correcting the moment around the Z axis; and introducing the tilting moment vector into the input of the second dynamic model to obtain the first dynamic model when the aircraft has the wall effect.

Determining the correction factors alpha and beta and the tilting moment vector M _y Based on the above, the second power of the correction factor alpha without wall effect can be further utilizedLearning the System Total Lift vector (F) of the model _b Component force in the Z-axis direction of the body) is corrected, and the reactive torque vector (M) of the second dynamic model in the absence of the wall surface effect is corrected by the correction factor β _b The amount of torque about the Z-axis) is corrected for the tilting torque vector M _y When the unmanned aerial vehicle has the wall effect, the tilting torque vector M can be independently added into the model in the modeling of the first dynamic model of the unmanned aerial vehicle _y Finally, a first dynamic model of the unmanned aerial vehicle during the wall effect is obtained, and the model structure diagram of the first dynamic model during the wall effect can be specifically referred to fig. 6.

Wherein, in figure 6, the first and second images,

l is a system total lift force correction matrix, and N is a system reactive torque correction matrix.

When having the wall effect unmanned aerial vehicle's first dynamic model compares with unmanned aerial vehicle's second dynamic model when not having the wall effect, in having brought the model into power that the wall effect brought and the change and the moment of verting, finally obtained the nonlinear dynamical system who contains the wall effect.

Step 203, determining a first space state equation when the aircraft has a wall effect based on the first dynamic model; the system matrix and the control matrix of the first spatial state equation comprise the distance.

According to a nonlinear dynamical system linearization theory, the first dynamical model is simplified and processed into a linear system at a system balance point of the first dynamical model, and a state space equation corresponding to the linear system after the first dynamical model is linearized is determined based on a relevant identification technology, such as Unscented Kalman Filter (UKF) parameter estimation, so as to obtain a first state space equation when the aircraft has a wall surface effect.

The first state space equation for the system with wall effect can be expressed as:

where x is a 9-dimensional system state vector in state space, x = [ u, v, w, p, q, r, φ, θ, ψ] ^T As described above, wherein (u, v, w) ^T Is the linear velocity vector of the machine body in three directions, (p, q, r) ^T Is the angular velocity vector of the organism in three directions (phi, theta, psi) ^T Is the Euler angle vector of the body. u is the normalized control input vector, u = [ u = [ [ u ] _col ,u _lat ,u _lon ,u _ped ] ^T Wherein u is _col ，u _lat ，u _lon And u _ped Respectively corresponding to the normalized control quantity of an accelerator (height), a transverse (rolling), a longitudinal (pitching) and a course (yawing) channel; a 'is a system matrix when the wall surface effect exists, B' is a control matrix when the wall surface effect exists, and A 'and B' comprise the distance d from the center of a rotor wing of the aircraft to the wall surface _WE 。

Step 204, constructing a first closed-loop system when the aircraft has a wall effect by using a given target feedback controller and a system matrix and a control matrix of the first space state equation; the target feedback controller is a feedback controller which can enable the second closed loop system to maintain stable when the aircraft has no wall surface effect.

The process of specifying the target feedback controller is described below.

Firstly, according to a nonlinear dynamical system linearization theory, the second dynamical model is simplified and processed into a linear system at a system balance point of the second dynamical model, and a state space equation corresponding to the linear system after the second dynamical model is linearized is determined based on a relevant identification technology, such as UKF parameter estimation and the like, so that a second state space equation when the aircraft has no wall surface effect is obtained.

The second state space equation when the system has no wall effect can be expressed as:

in the formula, A is a system matrix without wall effect, and B is a control matrix without wall effect; unlike A 'and B', A and B do not include the distance d from the center of the rotor to the wall surface of the aircraft _WE . The meanings of x and u can be found in the above description.

And then, an open-loop system and a closed-loop system of the unmanned aerial vehicle without the wall effect can be further determined according to the system matrix A and the control matrix B in the second state space equation without the wall effect.

The expression of the open-loop system without wall effect is as follows:

G(s)＝C(sI-A) ^-1 B+D；

in the formula, s is a complex variable, I is an identity matrix, C and D are constants, and preferably, C = eye (9) D = zeros (9, 4).

The expression of the closed-loop system (i.e., the second closed-loop system) in the absence of the wall effect is as follows:

the ducted unmanned aerial vehicle is an unstable open-loop system, and needs a feedback controller to adjust to ensure the stability of the unmanned aerial vehicle, so that a feedback controller which can enable the closed-loop system of the unmanned aerial vehicle to be stable and usable when no wall surface effect exists can be designed, for example, an LQR controller, the controller matrix is K, and the controller which can enable the closed-loop system of the unmanned aerial vehicle to maintain stability when no wall surface effect exists can be used as the given target feedback controller.

After the target feedback controller is determined, a first closed-loop system of the aircraft during the wall effect can be constructed according to the target feedback controller and the system matrix A 'and the control matrix B' of the first space state equation.

Specifically, the expression of the open loop system in the case of the wall effect is as follows:

G′(s)＝C(sI-A′) ^-1 B′+D；

for the meanings of the letters in the formulae, reference is made to the above.

The expression of the closed-loop system in which the wall surface effect is effective (i.e., the first closed-loop system) is as follows:

in the formula, the value of K is the controller matrix of the target feedback controller.

And step 205, determining the minimum value of the distance which can enable the first closed loop system to maintain stable, and obtaining the minimum safe distance from the aircraft to the wall surface.

In the case of wall effect, due to d _WE Change in/R, system resultant force vector F _b And aerodynamic moment vector M _b All change with moment vector etc. vert, lead to duct formula unmanned aerial vehicle's dynamics model expression also to change, correspondingly also can lead to closed loop system

With consequent changes. The stability judgment condition of the multi-input multi-output closed loop system comprises that all characteristic values of a system matrix A' have negative real parts, but the method is not limited in this way, therefore, the minimum distance from the unmanned aerial vehicle to the wall surface can be calculated and obtained based on the condition when the stability of the system can be guaranteed, and the distance is the minimum safety distance from the unmanned aerial vehicle to the wall surface on the premise that the first closed loop system can be kept stable, namely the minimum safety distance from the unmanned aerial vehicle to the wall surface when the unmanned aerial vehicle can be in balanced and stable approach to the wall surface under the working condition of hovering.

And 206, performing flight control on the aircraft based on the minimum safe distance.

Finally, flight control may be performed on the aircraft as it needs to hover near the wall to perform aerial work based on the minimum safe distance.

When the aircraft is close to the wall surface to work, the distance between the aircraft and the wall surface is controlled to be at least not less than the minimum safety distance, so that the stability and the safety of the aircraft in the process of closing the wall surface to work in the air are guaranteed. Specifically, the minimum allowable approach distance between the aircraft and the wall surface when the aircraft approaches the wall surface and suspends may be set according to the configuration of the aircraft and/or the type of the controller within a range greater than or equal to the minimum safe distance, and the minimum allowable approach distance is within a range greater than or equal to the minimum safe distance, so as to ensure the safety and stability of the aircraft during operation under the condition of approaching the wall surface and suspending.

It should be noted that, after the feedback controller with a good effect is selected for the unmanned aerial vehicles of the same type and model, the minimum safe distance is unchanged, so that the processing procedure for determining the minimum safe distance from the unmanned aerial vehicle to the wall surface can be completed in advance, and subsequently, the flight control during approaching the unmanned aerial vehicle to the wall surface operation can be directly performed based on the predetermined minimum safe distance.

In summary, compared with an open rotor aircraft, the ducted aircraft can meet the requirement of high-altitude approach flight, and compared with the existing scheme, the method researches the relationship between the wall effect generated when the aircraft approaches the wall surface and the distance between the aircraft and the wall surface, considers the influence brought by the wall effect into the construction of an aircraft model, obtains the relationship between the distance between the aircraft and the wall surface and the system stability through analysis, and further converts the relationship into the minimum safe distance allowing approach, namely the minimum safe distance between the aircraft and the wall surface under the condition of stable whole system, performs flight control on the aircraft based on the minimum safe distance obtained by considering the wall effect, and obviously improves the stability and safety when the aircraft approaches the wall surface to fly (mainly refers to the working condition that the approach wall surface hovers to execute operation).

Corresponding to the flight control method of the aircraft, an alternative embodiment of the present application further discloses a flight control device of an aircraft, and referring to fig. 7, the flight control device includes:

a first determining unit 701, configured to determine a resultant force vector and an association relationship between a resultant torque vector of the aircraft and a distance between the aircraft and the wall surface under the wall surface effect;

a first building unit 702, configured to build, based on the association relationship, a first dynamic model when the aircraft has a wall effect; the first dynamic model comprises the resultant force vector and the resultant moment vector expressed based on the distance;

a second determining unit 703, configured to determine, based on the first dynamic model, a first spatial state equation when the aircraft has a wall effect; the system matrix and the control matrix of the first space state equation comprise the distance;

a second constructing unit 704, configured to construct a first closed-loop system when the aircraft has a wall effect, by using a given target feedback controller and a system matrix and a control matrix of the first space state equation; the target feedback controller is a feedback controller which can enable the second closed-loop system to maintain stable when the aircraft has no wall effect;

a third determining unit 705, configured to determine a minimum value of the distance that enables the first closed-loop system to maintain stable, so as to obtain a minimum safe distance from the aircraft to the wall surface;

a control unit 706 for controlling the flight of the aircraft based on the minimum safe distance.

In an alternative embodiment of the disclosed embodiment, the distance from the aircraft to the wall surface is the distance d from the center of the aircraft rotor to the wall surface _WE The resultant force vector comprises: the total lift vector and the gravity vector of the system when the aircraft is in the wall effect hovering working condition; the resultant torque vector includes: the reaction torque vector and the tilting torque vector of the aircraft under the wall effect hovering working condition;

the first determining unit 701 is specifically configured to:

based on the ratio d of the total lift force vector, the reaction torque vector and the tilting torque vector of the system to the distance respectively _WE The association relation between the/R and the system sum is determinedLift force vector, reaction torque vector and tilting torque vector are respectively connected with distance d _WE The incidence relation between the two;

In an optional implementation manner of the embodiment of the present application, as shown in fig. 8, the method may further include: a third building unit 707 for:

before the first building unit 702 builds the first dynamic model when the aircraft has the wall effect based on the association relationship, a second dynamic model when the aircraft has no wall effect is built; the inputs to the second dynamical model include a resultant force vector F to which the aircraft is subjected excluding gravity _b Aerodynamic moment vector M to which the whole aircraft is subjected _b And aircraft gravity F _g The output comprises a linear velocity vector, an angular velocity vector and an Euler angle vector of an aircraft body, and the total system lift vector of the aircraft is the resultant external force vector F _b Component force in Z-axis direction of the aircraft body, and reaction torque vector of the aircraft is aerodynamic moment vector M _b An amount of moment about the Z-axis.

In an optional implementation manner of the embodiment of the present application, the first constructing unit 702 is specifically configured to:

determining a correction factor alpha for correcting the total lift vector of the system and a correction factor beta for correcting the reaction torque vector based on the incidence relation, and determining an expression of the tilting torque vector; the distance d is included in the expressions of the correction factors alpha and beta and the tilting moment vector _WE ；

Using the correction factor alpha to the resultant external force vector F in the second dynamic model _b Correcting component force in the Z-axis direction of the machine body; using the correction factor beta to the aerodynamic moment vector M in the second dynamic model _b Correcting the moment around the Z axis; and introducing the tilting moment into the input of the second dynamic model to obtain the first dynamic model when the aircraft has the wall effect.

In an optional implementation manner of the embodiment of the present application, each of the first kinetic model and the second kinetic model is a nonlinear system;

the second determining unit 703 is specifically configured to:

the second constructing unit 704 is specifically configured to:

based on a preset identification technology, determining a state space equation corresponding to the linear system after the second dynamic model is linearized, and obtaining a second state space equation when the aircraft has no wall effect;

The flight control device of the aircraft disclosed in the embodiment of the present application is relatively simple in description because it corresponds to the flight control method of the aircraft disclosed in the above embodiment, and for the relevant similarities, please refer to the description of the flight control method part of the aircraft in the above embodiment, and details are not described here.

In addition, the application also discloses an aircraft which is a ducted aircraft, and more particularly, the aircraft can be but is not limited to a coaxial counter-oar double-ducted unmanned aerial vehicle. With reference to the schematic structural diagram of the aircraft shown in fig. 8, the aircraft may comprise:

a fuselage 801 and at least two ducted propeller systems 802;

wherein, under the condition that the aircraft includes two ducted propeller systems 802, the aircraft may further include two control rudders, the two ducted propeller systems 802 adopt a longitudinal form and are symmetrically arranged on both sides of the fuselage 801, and the two control rudders are respectively and fixedly connected below the ducts of each ducted propeller system 802. Under the condition that the aircraft comprises more than two ducted propeller systems 802, the aircraft can fly by differential steering of propellers in different ducts, certainly, the aircraft can also fly by means of a control rudder, and the control can be more stable by means of the control rudder, so that the effect is better.

The specific structure and functions of the ducted aircraft can be described with reference to fig. 1 and the related description of the structure and functions of the ducted unmanned aerial vehicle with reference to fig. 1, and are not repeated here.

In addition, the aircraft comprises a controller 804 for flight control of the aircraft based on the minimum safe distance determined in the flight control method as described above; alternatively, an external control signal is received and the aircraft is subjected to flight control based on the control signal, the control signal being a signal generated based on the minimum safe distance in the flight control method as described above.

Specifically, as an optional implementation manner, the aircraft such as the unmanned aerial vehicle can be subjected to flight control on the aircraft by taking the self-controller as an execution subject based on the minimum safety distance determined in the flight control method, so as to ensure the stability and safety performance of the aircraft when the aircraft flies close to the wall surface in the air; or, as another optional embodiment, the control device may further receive an external control signal, where the external control signal may be, for example, a control signal generated by a control handle or a control station of the unmanned aerial vehicle based on the minimum safety distance, and after the unmanned aerial vehicle receives the external control signal, the unmanned aerial vehicle controls a working condition that the unmanned aerial vehicle works close to the wall surface based on the external control signal, and by controlling a distance between the aircraft and the wall surface to be at least not less than the minimum safety distance, stability and safety performance of the aircraft flying close to the wall surface in the air are guaranteed.

In summary, compared with an open rotor aircraft, the ducted aircraft can meet the requirement of high-altitude approach flight, and compared with the existing scheme, the ducted aircraft researches the relationship between the wall effect generated when the aircraft approaches the wall surface and the distance between the aircraft and the wall surface, considers the influence brought by the wall effect in the construction of an aircraft model, obtains the relationship between the distance between the aircraft and the wall surface and the system stability through analysis, obtains a minimum safe distance allowing approach through conversion, namely the minimum safe distance between the aircraft and the wall surface on the premise of the complete machine system stability, performs flight control on the aircraft based on the minimum safe distance obtained by considering the avoidance effect, and obviously improves the stability and safety of the aircraft during working. Based on this application scheme, when unmanned aerial vehicle is close the wall during operation, through control the distance between unmanned aerial vehicle and the wall not less than at least minimum safe distance can make stability and security when the aircraft is close the wall operation in the air can ensure.

It should be noted that, in the present specification, the embodiments are all described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments may be referred to each other.

For convenience of description, the above system or apparatus is described as being divided into various modules or units by function, respectively. Of course, the functionality of the various elements may be implemented in the same one or more pieces of software and/or hardware in the practice of the present application.

From the above description of the embodiments, it is clear to those skilled in the art that the present application can be implemented by software plus a necessary general hardware platform. Based on such understanding, the technical solutions of the present application may be essentially or partially implemented in the form of a software product, which may be stored in a storage medium, such as a ROM/RAM, a magnetic disk, an optical disk, etc., and includes several instructions for enabling a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method according to the embodiments or some parts of the embodiments of the present application.

Finally, it is further noted that, herein, relational terms such as first, second, third, fourth, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising a," "8230," "8230," or "comprising" does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element.

The foregoing is only a preferred embodiment of the present application and it should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present application, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. The flight control method of the aircraft is characterized in that the aircraft is a ducted aircraft; the method comprises the following steps:

determining the incidence relation between the resultant force vector and resultant moment vector of the aircraft and the distance from the aircraft to the wall surface under the wall surface effect, wherein the distance from the aircraft to the wall surface is the distance d from the center of a rotor wing of the aircraft to the wall surface _WE Said resultant force vector comprising: the total lift vector and the gravity vector of the system when the aircraft is in the wall effect hovering working condition; the resultant torque vector includes: when the aircraft is hovering in the presence of wall effectA reaction torque vector and a tilting torque vector;

constructing a first dynamic model of the aircraft when the aircraft has a wall effect based on the incidence relation; the first dynamic model comprises the resultant force vector and the resultant moment vector expressed based on the distance;

controlling the flight of the aircraft based on the minimum safe distance;

wherein before the building of the first dynamic model when the aircraft has the wall effect based on the incidence relation, the method further comprises the following steps:

constructing a second dynamic model when the aircraft has no wall effect; the inputs to the second dynamical model include a resultant force vector F to which the aircraft is subjected excluding gravity _b Aerodynamic moment vector M to which the whole aircraft is subjected _b And aircraft gravity F _g The output comprises a linear velocity vector, an angular velocity vector and an Euler angle vector of an aircraft body, and the total system lift vector of the aircraft is the resultant external force vector F _b Component force in the Z-axis direction of the body, and the reaction torque vector of the aircraft is the aerodynamic moment vector M _b An amount of moment about the Z axis;

wherein the building of the first dynamic model of the aircraft with the wall effect based on the incidence relation comprises the following steps:

determining a correction factor alpha and a correction factor pair for correcting the total lift vector of the system based on the incidence relationA correction factor beta for correcting the reaction torque vector is obtained, and an expression of the tilting torque vector is determined; the expressions of the correction factors alpha and beta and the tilting moment vector include the distance d _WE ；

Using the correction factor alpha to the resultant force vector F in the second dynamic model _b Correcting component force in the Z-axis direction of the machine body; using the correction factor beta to the aerodynamic moment vector M in the second dynamic model _b Correcting the moment around the Z axis; and introducing the tilting moment vector into the input of the second dynamic model to obtain the first dynamic model when the aircraft has the wall effect.

2. The method of claim 1,

3. The method of claim 1, wherein the first kinetic model is a non-linear system; the determining a first space state equation when the aircraft has the wall effect based on the first dynamic model comprises:

4. The method of claim 3, wherein the second kinetic model is a non-linear system; the method for constructing the first closed-loop system when the aircraft has the wall effect by using a given target feedback controller and the system matrix and the control matrix of the first space state equation comprises the following steps:

linearizing the second kinetic model into a linear system at a system equilibrium point of the second kinetic model;

5. A flight control device of an aircraft is characterized in that the aircraft is a ducted aircraft; the device comprises:

a first determining unit, configured to determine a correlation between a resultant force vector and a resultant moment vector of the aircraft and a distance from the aircraft to the wall surface under the wall surface effect, where the distance from the aircraft to the wall surface is a distance d from a center of a rotor of the aircraft to the wall surface _WE Said resultant force vector comprising: the total system lift vector and the gravity vector of the aircraft under the wall effect hovering working condition; the resultant torque vector includes: the reaction torque vector and the tilting torque vector of the aircraft under the wall effect hovering working condition;

the first building unit is used for building a first dynamic model when the aircraft has the wall effect based on the incidence relation; the first dynamic model comprises the resultant force vector and the resultant moment vector expressed based on the distance;

the second determining unit is used for determining a first space state equation when the aircraft has the wall effect based on the first dynamic model; the system matrix and the control matrix of the first space state equation comprise the distance;

the second construction unit is used for constructing a first closed-loop system when the aircraft has the wall effect by utilizing a given target feedback controller and a system matrix and a control matrix of the first space state equation; the target feedback controller is a feedback controller which can enable the second closed-loop system to maintain stable when the aircraft has no wall surface effect;

a third determining unit, configured to determine a minimum value of the distance that enables the first closed-loop system to maintain stability, so as to obtain a minimum safe distance from the aircraft to the wall surface;

a control unit for controlling the flight of the aircraft based on the minimum safe distance;

the third construction unit is used for constructing a second dynamic model when the aircraft has no wall effect before the first construction unit constructs the first dynamic model when the aircraft has the wall effect based on the incidence relation; the inputs to the second dynamical model include a resultant force vector F to which the aircraft is subjected excluding gravity _b Aerodynamic moment vector M to which the whole aircraft is subjected _b And aircraft gravity F _g The output comprises a linear velocity vector, an angular velocity vector and an Euler angle vector of an aircraft body, and the total system lift vector of the aircraft is the resultant external force vector F _b Component force in the Z-axis direction of the body, and the reaction torque vector of the aircraft is the aerodynamic torque vectorM _b An amount of moment about the Z axis;

the first building unit is specifically configured to:

6. The apparatus of claim 5,

the first determining unit is specifically configured to:

7. The apparatus of claim 5, wherein the first kinetic model and the second kinetic model are each a non-linear system;

the second determining unit is specifically configured to:

the second building unit is specifically configured to:

8. An aircraft, characterized in that it comprises: the aircraft body and at least two ducted propeller systems;

further comprising:

a controller for flight control of the aircraft based on the minimum safe distance in the method according to any one of claims 1-4; or, receiving an external control signal and performing flight control on the aircraft based on the control signal, wherein the control signal is a signal generated based on the minimum safe distance in the method according to any one of claims 1 to 4.