CN116009421A - Universal simulation method for full-freedom fixed-wing aircraft - Google Patents
Universal simulation method for full-freedom fixed-wing aircraft Download PDFInfo
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Abstract
The invention provides a general simulation method of a full-freedom fixed-wing aircraft, which comprises the following steps: planning an expected flight track, and simulating a fixed wing aircraft; acquiring the current position, the current airspeed and the actual attitude angle of the fixed-wing aircraft in the simulation step length; acquiring control surface adjustment quantity and throttle adjustment quantity of the fixed wing aircraft based on the expected flight track, the current position, the current airspeed and the actual attitude angle of the fixed wing aircraft; and adjusting the fixed wing aircraft based on the control surface adjustment amount and the throttle adjustment amount to complete the simulation of the motion characteristics of the fixed wing aircraft. The invention realizes the gesture and position control, can complete automatic driving according to the task waypoints, designs an automatic interpolation smoothing algorithm of the waypoints on a sub-basis, and avoids the phenomenon that part of task routes on two waypoints which are far apart are connected with each other due to the curvature of the earth are lower than a sea level.
Description
Technical Field
The invention belongs to the technical field of simulation, and particularly relates to a general simulation method for a full-freedom fixed-wing aircraft.
Background
The fight simulation deduction software needs mathematical models of various weaponry equipment to simulate the movement process of the equipment and further simulate the fight performance of the equipment on the basis. As a basis for modern aeronautical forces, a simulation model of a fixed-wing aircraft is indispensable. Unmanned planes, fighters, bombers, and even cruise missiles can fall into the category of fixed wing aircraft.
In a combat deduction simulation environment, an aerial target such as a fixed-wing combat aircraft, a fixed-wing unmanned aerial vehicle, a cruise missile and the like is one of the most common weaponry. However, full-degree-of-freedom aircraft models are an interdisciplinary problem involving aerodynamics, aircraft design, and attitude control, and three degrees of freedom particle simulation fixed-wing aircraft have traditionally been employed to simplify the model. Although the particle model is simple and convenient, the defect of the particle model is more prominent along with the continuous improvement of the requirements of operational simulation deduction on the equipment performance fidelity:
the three-degree-of-freedom aircraft model based on rigid particles cannot truly simulate the motion state of an aircraft in simulation scenes such as fight deduction and the like due to lack of attitude data.
In normal combat and empty pipe scenarios, which typically have low, medium and high speed aircraft, a kinetic model is required that simulates various airspeeds to simulate various aircraft in scene deduction.
The position and posture data output by the dynamic model are abstract, and if visual display can be realized, the user can accurately grasp the flight state.
In combat deduction, formation and multi-machine parallel simulation are often caused, and time sequence control becomes an important factor affecting simulation effect.
Disclosure of Invention
In order to solve the technical problems, the invention provides a general simulation method of a full-freedom fixed-wing aircraft, which realizes gesture and position control and can complete automatic driving according to a task waypoint. An automatic interpolation smoothing algorithm of the waypoints is designed on the sub-basis, and the phenomenon that part of task routes on the connecting lines of two waypoints which are far apart are lower than a sea level due to the curvature of the earth is avoided.
In order to achieve the above object, the present invention provides a general simulation method for a full-freedom fixed wing aircraft, including:
planning an expected flight track, and simulating a fixed wing aircraft;
acquiring the current position, the current airspeed and the actual attitude angle of the fixed-wing aircraft in the simulation step length;
acquiring control surface adjustment quantity and throttle adjustment quantity of the fixed wing aircraft based on the expected flight track, the current position, the current airspeed and the actual attitude angle of the fixed wing aircraft;
and adjusting the fixed wing aircraft based on the control surface adjustment amount and the throttle adjustment amount to complete the simulation of the motion characteristics of the fixed wing aircraft.
Optionally, acquiring the current position and the actual attitude angle of the fixed-wing aircraft includes:
the stress condition and the rotation moment of each direction of the fixed wing aircraft are obtained;
decomposing the stress condition and the rotation moment to all directions of a carrier coordinate system, and obtaining components of force and moment;
based on the components of the force and the moment, acquiring the speed and the angular speed of the fixed wing aircraft in each direction of the current step length;
integrating the speeds and the angular speeds in all directions, acquiring the displacement and the rotation angle of the fixed wing aircraft in the current step length, and acquiring the current position and the actual attitude angle based on the displacement and the rotation angle.
Optionally, obtaining the control surface adjustment amount of the fixed-wing aircraft includes:
acquiring a desired position based on the desired flight trajectory, and randomly setting a desired airspeed;
acquiring a desired attitude angle based on the current position and the desired position;
acquiring an attitude error based on the expected attitude angle and the actual attitude angle;
and acquiring the control surface adjustment quantity of the fixed wing aircraft based on the attitude error.
Optionally, acquiring the throttle adjustment of the fixed-wing aircraft includes:
and acquiring an airspeed error based on the current airspeed and the expected airspeed, and acquiring the throttle adjustment of the fixed-wing aircraft based on the airspeed error.
Optionally, obtaining the desired attitude angle includes:
acquiring a position error between the current position and the expected position;
and acquiring the expected attitude angle based on the position error.
Optionally, the desired attitude angle includes: a desired roll angle and a desired pitch angle;
acquiring the desired attitude angle includes:
decomposing the position error into a heading error in a horizontal plane and an elevation error in a vertical direction;
acquiring the expected roll angle based on the heading error;
and acquiring the expected pitch angle based on the elevation error.
Optionally, adjusting the fixed wing aircraft includes:
adjusting the heading error and the altitude error of the fixed-wing aircraft based on the control surface adjustment;
and adjusting the airspeed error of the fixed-wing aircraft based on the throttle adjustment.
Optionally, planning the desired flight trajectory includes:
planning a route point, and acquiring an initial expected flight track based on the route point;
and carrying out self-smoothing processing on the initial expected flight trajectory to obtain the expected flight trajectory.
Optionally, performing the self-smoothing process on the initial desired flight trajectory includes:
acquiring a linear distance d between two adjacent waypoints in the initial expected flight trajectory;
if the straight line distance D is larger than a preset distance threshold D, calculating a D/D value, and rounding up the D/D value to obtain an integer n;
inserting n-1 route points between two adjacent route points, and dividing the route between the two adjacent route points into n parts;
and if the linear distance D between the divided adjacent two waypoints is smaller than the preset distance threshold D, ending the self-smoothing processing.
Optionally, setting the desired airspeed includes:
acquiring an air speed ratio based on the desired airspeed and a standard airspeed; the airspeed ratio is: p=v/Vs, p represents the air speed ratio, vs represents the standard airspeed, V represents the desired airspeed;
when 0< p <1, calculating the position and the posture of the model according to the standard airspeed Vs, multiplying the current position by p for equal-proportion reduction before outputting the current position, and keeping the actual posture angle unchanged;
when p=1, calculating the position and the posture of the model according to the standard airspeed Vs, and normally outputting the current position and the actual posture angle;
when p is more than 1, calculating the position and the gesture of the model according to the standard airspeed Vs, and shortening the time point of external output from t to ta+ (t-ta)/p; the time point of the external output is as follows: the cumulative time after the start of the simulation, ta, represents the time at which the airspeed is changed.
Compared with the prior art, the invention has the following advantages and technical effects:
according to the dynamics equation, a full-freedom dynamics model of the fixed wing aircraft is established as a kernel, attitude and position control is realized, and automatic driving can be completed according to the mission waypoints. An automatic interpolation smoothing algorithm of the waypoints is designed on the sub-basis, and the phenomenon that part of task routes on the connecting lines of two waypoints which are far apart are lower than a sea level due to the curvature of the earth is avoided.
The simulation algorithm of dynamic step length under the virtual time domain is designed, and a basic dynamics model kernel can be used for simulating a fixed wing aircraft which spans various airspeeds of low, medium and high. The method solves the actual requirements of the airplane with low speed, medium speed and high speed in the deduction scene, and simultaneously saves the workload of independently modeling the airplane in each speed interval, thereby realizing the generalization of the airplane model.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application, illustrate and explain the application and are not to be construed as limiting the application. In the drawings:
FIG. 1 is a schematic diagram of a dynamics model and a flight control system according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a simulation flow of a fixed wing aircraft model in accordance with an embodiment of the present invention;
FIG. 3 is a schematic view of an embodiment of the present invention with waypoint connection altitude below sea level;
FIG. 4 is a schematic diagram of simulation results of a single-machine model driver visual software according to an embodiment of the present invention;
FIG. 5 is a visual schematic diagram of a multi-machine formation parallel simulation according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of an automatic interpolation smoothing algorithm for waypoints according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of an airspeed simulation algorithm for space-time output proportional adjustment in accordance with an embodiment of the present invention;
fig. 8 is a timing control schematic diagram of formation flight according to an embodiment of the present invention.
Detailed Description
It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
It should be noted that the steps illustrated in the flowcharts of the figures may be performed in a computer system such as a set of computer executable instructions, and that although a logical order is illustrated in the flowcharts, in some cases the steps illustrated or described may be performed in an order other than that illustrated herein.
The invention provides a general simulation method of a full-freedom fixed-wing aircraft, which comprises the following steps:
planning an expected flight track, and simulating a fixed wing aircraft;
acquiring the current position, the current airspeed and the actual attitude angle of the fixed-wing aircraft in the simulation step length;
acquiring control surface adjustment quantity and throttle adjustment quantity of the fixed wing aircraft based on the expected flight track, the current position, the current airspeed and the actual attitude angle of the fixed wing aircraft;
and adjusting the fixed wing aircraft based on the control surface adjustment amount and the throttle adjustment amount to complete the simulation of the motion characteristics of the fixed wing aircraft.
Further, obtaining the current position and the actual attitude angle of the fixed-wing aircraft includes:
the stress condition and the rotation moment of each direction of the fixed wing aircraft are obtained;
decomposing the stress condition and the rotation moment to all directions of a carrier coordinate system, and obtaining components of force and moment;
based on the components of the force and the moment, acquiring the speed and the angular speed of the fixed wing aircraft in each direction of the current step length;
integrating the speeds and the angular speeds in all directions, acquiring the displacement and the rotation angle of the fixed wing aircraft in the current step length, and acquiring the current position and the actual attitude angle based on the displacement and the rotation angle.
Further, obtaining the control surface adjustment amount of the fixed wing aircraft includes:
acquiring a desired position based on the desired flight trajectory, and randomly setting a desired airspeed;
acquiring a desired attitude angle based on the current position and the desired position;
acquiring an attitude error based on the expected attitude angle and the actual attitude angle;
and acquiring the control surface adjustment quantity of the fixed wing aircraft based on the attitude error.
Further, obtaining the throttle adjustment of the fixed wing aircraft includes:
and acquiring an airspeed error based on the current airspeed and the expected airspeed, and acquiring the throttle adjustment of the fixed-wing aircraft based on the airspeed error.
Further, obtaining the desired attitude angle includes:
acquiring a position error between the current position and the expected position;
and acquiring the expected attitude angle based on the position error.
Further, the desired attitude angle includes: a desired roll angle and a desired pitch angle;
acquiring the desired attitude angle includes:
decomposing the position error into a heading error in a horizontal plane and an elevation error in a vertical direction;
acquiring the expected roll angle based on the heading error;
and acquiring the expected pitch angle based on the elevation error.
Further, adjusting the fixed wing aircraft includes:
adjusting the heading error and the altitude error of the fixed-wing aircraft based on the control surface adjustment;
and adjusting the airspeed error of the fixed-wing aircraft based on the throttle adjustment.
Further, planning the desired flight trajectory includes:
planning a route point, and acquiring an initial expected flight track based on the route point;
and carrying out self-smoothing processing on the initial expected flight trajectory to obtain the expected flight trajectory.
Further, performing a self-smoothing process on the initial desired flight trajectory includes:
acquiring a linear distance d between two adjacent waypoints in the initial expected flight trajectory;
if the straight line distance D is larger than a preset distance threshold D, calculating a D/D value, and rounding up the D/D value to obtain an integer n;
inserting n-1 route points between two adjacent route points, and dividing the route between the two adjacent route points into n parts;
and if the linear distance D between the divided adjacent two waypoints is smaller than the preset distance threshold D, ending the self-smoothing processing.
Further, setting the desired airspeed includes:
acquiring an air speed ratio based on the desired airspeed and a standard airspeed; the airspeed ratio is: p=v/Vs, p represents the air speed ratio, vs represents the standard airspeed, V represents the desired airspeed;
when 0< p <1, calculating the position and the posture of the model according to the standard airspeed Vs, multiplying the current position by p for equal-proportion reduction before outputting the current position, and keeping the actual posture angle unchanged;
when p=1, calculating the position and the posture of the model according to the standard airspeed Vs, and normally outputting the current position and the actual posture angle;
when p is more than 1, calculating the position and the gesture of the model according to the standard airspeed Vs, and shortening the time point of external output from t to ta+ (t-ta)/p; the time point of the external output is as follows: the cumulative time after the start of the simulation, ta, represents the time at which the airspeed is changed.
Examples
The embodiment provides a general simulation method of the full-freedom fixed-wing aircraft; the universal fixed wing aircraft simulation model is designed, the motion characteristics of the fixed wing aircraft can be simulated, the fixed wing aircraft is matched with the fixed wing aircraft simulation model in posture and guidance control, and the fixed wing aircraft simulation model has the capability of automatic flight. The model can simulate various air targets for the comprehensive simulation platform.
Fixed wing aircraft: aerocraft with an inactive wing designed on the coanda effect as a lift principle is the most common aircraft configuration. Compared with another common aircraft helicopter, the fixed wing aircraft has the outstanding advantages of large lift coefficient, fuel saving, high speed and long voyage; however, the suspension is impossible, and stall is easy to occur when the speed is too low.
Full degree of freedom: the movement of the object can be decomposed into translation and rotation. Establishing a three-dimensional Cartesian reference coordinate system, wherein the translation of the mass center along 3 coordinate axes is 3 degrees of freedom; the pitch, roll and yaw of the object about these 3 coordinate axes are then 3 rotational degrees of freedom. The 6 degrees of freedom describing the translation and rotation of the aircraft are collectively referred to as the full degree of freedom.
Generalizing: it means that a set of full-freedom aircraft models can simulate various aircraft from low speed to high speed, and different examples of the models can play different roles in the simulation deduction environment. All aircraft have 6 degrees of freedom in position and posture, and can truly simulate the motion of the aircraft.
The implementation of the method mainly depends on a dynamics model and a flight control system, and as shown in fig. 1, the functions of the method are as follows:
1) The dynamic model is a motion model which is built according to the aerodynamic characteristics of the fixed wing aircraft and has the functions of translation and rotation.
2) The flight control module takes the position and the gesture as feedback signals, and subtracts the expected position and the current position to obtain a position error, and the flight control module converts the position error into expected heading, pitching and rolling signals, namely the expected gesture by using a PID control rate; the expected gesture is subtracted from the current gesture to obtain a gesture error, and 3 control surfaces of a rudder, an elevator and an aileron of the aircraft are adjusted by a flight control, so that the gesture error is eliminated. The airspeed control and attitude control of the aircraft are substantially decoupled and are directly throttle adjusted.
The aircraft executes a flight mission on the comprehensive simulation platform, and begins with planning mission waypoints, and the connection line of the mission waypoints is the expected flight track. After the simulation starts, the general model controls the aircraft to adjust the attitude and move along the expected track.
The method for controlling the position comprises the following steps:
a) The position error is decomposed into heading error in the horizontal plane and elevation error in the vertical direction.
b) The heading error is converted into a desired roll angle by processing with a PID controller. Because the roll motion and yaw motion of the fixed wing aircraft are coupled, the heading error of the aircraft can be finally eliminated through moderate roll.
c) The elevation error is converted into a desired pitch angle by processing with a PID controller. Pitching motion controls the climb and dive of the aircraft, enabling the fly height to be varied.
Attitude control of the aircraft is achieved at the periphery of the position control. The specific method comprises the following steps:
a) And adjusting the aileron to control the roll, and controlling the heading by using the coupling relation of the roll and the heading.
b) The pitch is controlled by adjusting the elevator, and the flying height is controlled by using the pitch.
c) If there is side-slip movement of the aircraft, the rudder is adjusted to inhibit side-slip and the airspeed vector is controlled to the longitudinal plane of symmetry of the aircraft.
d) The desired airspeed and the actual airspeed are subtracted to obtain airspeed error, and the throttle is adjusted to eliminate the airspeed error so as to achieve the purpose of controlling the airspeed.
As shown in FIG. 2, in one simulation step, each model of the aircraft performs simulation calculations according to the following steps:
1) And calculating the lift force and the resistance under the current airspeed and the attitude and the rotation moment of the aircraft in all directions by using a dynamics model.
2) The force and moment of the airplane are decomposed into all directions of a carrier coordinate system, and the components of the force and moment are obtained.
3) Based on the force and moment components, the speed and angular velocity of the aircraft in each direction of the current step size are calculated.
4) Integrating the speeds and the angular speeds in all directions to obtain the displacement and the rotation angle of the aircraft in the step length, and obtaining the position and the attitude of the aircraft.
5) A position error between the current position and the desired position (the next waypoint to be traveled to) is calculated.
6) The flight control module converts the position error into a desired attitude angle using the PID control rate.
7) And making a difference between the expected attitude angle and the actual attitude angle to obtain an attitude error.
8) And the flight control module calculates the control surface adjustment quantity of the aircraft according to the attitude error.
9) The current airspeed is subtracted from the desired airspeed to obtain a speed error, and the speed error is multiplied by an adjustment coefficient to obtain the throttle adjustment of the aircraft, so that the actual airspeed of the next step is closer to the desired airspeed.
As long as the position and the gesture of each airplane can be accurately controlled, the simulation of multiple airplanes can be further realized, because the multiple airplane simulation is a parallel extension of single machine simulation.
The aircraft model flies according to the connecting line of the waypoints under the control of an autopilot algorithm, and the expected flight track corresponding to the two adjacent remote waypoints is likely to appear in a part lower than the sea level. As shown in fig. 3.
If two adjacent waypoints a and B are too far apart, a portion of the corresponding desired wayline segment AB will be below sea level, subject to the curvature of the earth. It is clear that such a mission plan is not practical. The problem of low elevation can be solved by inserting new waypoints C, D between A, B and adjusting the desired way to ACDB using an automatic interpolation smoothing algorithm.
In a task planning stage of an initial simulation stage, a user sequentially inputs route points of an airplane by means of a simulation guiding and adjusting program, and a flight track is set; after the expected track is subjected to self-smoothing treatment, the aircraft flies in a more reasonable path, so that the phenomenon that an error movement path which is violated to normal is generated in simulation due to low elevation is avoided.
The more the combat scene simulation approaches the real environment, the more accurate the simulation of the equipment performance is realized, and the simulation of the single machine model driven visualization software is shown in fig. 4. The same is true of aircraft models, real world fighter aircraft, having different performance parameters to meet the respective fighter needs, where the most critical performance index is airspeed. To simulate wide-spectrum flight targets with low to high airspeed, algorithms have been designed that can adjust the spatio-temporal output signal to the aircraft dynamics model. The algorithm realizes simulation of different airspeed aircrafts by using one core model, and obviously saves development and maintenance costs.
The generalized simulation model supports multi-machine parallel simulation, including formation flight, as shown in fig. 5. The multi-machine parallel simulation has high requirements on the time sequence control of each plane. The simulation steps of all aircraft must be exactly synchronized to be consistent in attitude and position control.
If simulation time sequences of a plurality of aircrafts cannot be kept synchronous, a lot of confusion is caused to a deduction process, for example, the aircrafts arrive at a preset position in advance or in retard, and the simulation time sequences cannot be matched with other models; for formation flights, if the simulation timing of members is not synchronized, formation confusion may result.
The processing flow of the automatic interpolation smoothing algorithm of the waypoints is as shown in fig. 6:
in the task planning stage, the straight line distance d between the newly input waypoint B and the last waypoint A is checked. If d is greater than the distance threshold value 50Km (generally set to 50-80 Km, 50Km is taken as 4 in the figure), calculating the value of d/50, rounding up to obtain an integer n, then interpolating the longitude and latitude high linearity between A and B, inserting n-1 route points to divide the route from A to B into n sections; if the B-to-A distance of the new way is less than the threshold, no interpolation smoothing is performed. The subsequent waypoints are then continuously input and processed according to the same logic until the mission planning is completed. The route point interpolation is necessarily processed according to the longitude and latitude height smoothing. If such rectangular navigation coordinate system is interpolated in the north east, the problem of the mission course being below sea level is still unavoidable.
The model opens an airspeed setting interface for this purpose, considering the user's need to dynamically adjust the aircraft airspeed to more truly reflect the flight motion. This requires that various airspeeds be simulated in addition to the conventional 9 simulation steps, as well as complement and refinement. In order to simulate fixed wing aircraft with various airspeeds by using a set of simulation models, the most straightforward approach is to build a dynamic model library that is sufficient to cover these airspeeds, however, the resulting model maintenance work is also quite burdensome and not practically feasible. The user randomly sets the aircraft airspeed through the open airspeed setting interface, and the set aircraft airspeed is the desired airspeed. The embodiment provides an airspeed simulation algorithm for adjusting the space-time output proportion, as shown in fig. 7, the airspeed simulation algorithm is used for adjusting the airspeed ratio of a standard model, and the output of a space-time signal is adjusted, so that the problem is solved on the basis of a standard dynamics model. Assuming that a new aircraft airspeed V is set at the time ta at the time of simulation, the calculated airspeed ratio p=v/Vs, vs representing the standard airspeed, which is the recommended flight speed of the standard model, for example 35m/s. This velocity is determined by the aerodynamic properties of the standard model; according to the value of p, 3 cases are treated:
and 0< p <1, calculating the position and the posture of the model according to the standard airspeed Vs, multiplying p before outputting the position component, and carrying out equal proportion reduction, wherein the posture component is kept unchanged. From the simulation effect, the airspeed is reduced by the same duration and shorter than the distance that the airspeed flies at Vs.
Position component: converting the displacement of the carrier coordinate system into vector components under the navigation coordinate system, wherein the vector components comprise displacement components of 3 components in the north direction, the east direction and the bottom direction; i.e. the current position of the acquired aircraft model. Gesture component: here, it refers to the euler angle describing the rotational relationship between the carrier coordinate system and the navigation coordinate system, including roll angle, pitch angle, and heading angle 3 to components; i.e. the actual attitude angle of the acquired aircraft model.
p=1, the position and attitude of the model are calculated as the standard airspeed Vs, the normal output position and attitude components.
And p is 1, the position and the gesture of the model are calculated according to the standard airspeed Vs, and the time point of external output is shortened to ta+ (t-ta)/p from t. From the simulation effect, the aircraft arrives at the same position earlier than the airspeed of Vs, and the airspeed is quickened. ta represents the time at which the airspeed is changed.
Each set of 6 degree-of-freedom outputs (3 displacement components +3 attitude angle components) corresponds to a simulation time t, which represents the accumulated time after the start of the simulation.
There are two ways to model airspeed on a standard model:
simulating low-speed flight, reducing the displacement component output by the standard model in equal proportion, but keeping the simulation time unchanged, so that the ratio of displacement to time is reduced, and obtaining the low-quick-result
The high-speed flight is simulated, the displacement component calculated by simulation is kept unchanged, the simulation output time after the airspeed is regulated is shortened, the ratio of the displacement to the time is increased, and the airspeed is increased.
The model supports multi-machine parallel simulation represented by formation, in which all members observe uniform and strict timing control. For formation simulation, the model comprehensively uses a promise-future template and an atomic template of C++, so that the next round of simulation is performed after all machines complete the same simulation step length of a long machine.
The timing control of the formation flight is shown in fig. 8, in which the signal quantity of all the wings is informed by the long-range aircraft, and is encapsulated by the condition-value. After finishing the simulation calculation of one step length, the long machine calls a notifyall function, all machine threads finish waiting to be shifted into an active state, and then the available threads are applied for in a thread pool, and the same simulation step length calculation is started respectively.
And after any one of the bureau threads finishes step length calculation, the self-subtracting atomic type counter. Because the counter is an atomic operation, the self-subtraction call can ensure that the counter returns to zero after the simulation thread of the last aircraft finishes the calculation of the step length, the value of the future variable is assigned at the moment, and the long aircraft can be reversely informed to start the simulation calculation of the next step length.
The embodiment has the following beneficial effects:
according to the dynamics equation, a full-freedom dynamics model of the fixed wing aircraft is established as a kernel, attitude and position control is realized, and automatic driving can be completed according to the mission waypoints. An automatic interpolation smoothing algorithm of the waypoints is designed on the sub-basis, and the phenomenon that part of task routes on the connecting lines of two waypoints which are far apart are lower than a sea level due to the curvature of the earth is avoided.
The simulation algorithm of dynamic step length under the virtual time domain is designed, and a basic dynamics model kernel can be used for simulating a fixed wing aircraft which spans various airspeeds of low, medium and high. The method solves the actual requirements of the airplane with low speed, medium speed and high speed in the deduction scene, and simultaneously saves the workload of independently modeling the airplane in each speed interval, thereby realizing the generalization of the airplane model.
The synchronous control strategy of parallel simulation of a plurality of planes is designed, and the time sequence control problem among threads of a long-wing aircraft is solved by replacing a mutual exclusive lock with an atomic variable.
The multifunctional aircraft simulation model in this embodiment has the following advantages:
the full-freedom-degree motion state of the fixed wing aircraft from low airspeed to high can be simulated, and the fixed wing aircraft has the capability of self-stabilizing the gesture and automatically flying according to the waypoint.
The device has the capability of automatically smoothing the waypoints, automatically overcomes the influence of the curvature of the earth, and ensures the accuracy of expected flight trajectories.
Reliable multithreading synchronous control can realize strict consistency of multi-machine parallel simulation on time sequence, which is the basic guarantee of formation control flight.
The foregoing is merely a preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions easily conceivable by those skilled in the art within the technical scope of the present application should be covered in the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (10)
1. The universal simulation method for the full-freedom fixed-wing aircraft is characterized by comprising the following steps of:
planning an expected flight track, and simulating a fixed wing aircraft;
acquiring the current position, the current airspeed and the actual attitude angle of the fixed-wing aircraft in the simulation step length;
acquiring control surface adjustment quantity and throttle adjustment quantity of the fixed wing aircraft based on the expected flight track, the current position, the current airspeed and the actual attitude angle of the fixed wing aircraft;
and adjusting the fixed wing aircraft based on the control surface adjustment amount and the throttle adjustment amount to complete the simulation of the motion characteristics of the fixed wing aircraft.
2. The full-degree-of-freedom fixed wing aircraft universal simulation method of claim 1, wherein obtaining the current position and actual attitude angle of the fixed wing aircraft comprises:
the stress condition and the rotation moment of each direction of the fixed wing aircraft are obtained;
decomposing the stress condition and the rotation moment to all directions of a carrier coordinate system, and obtaining components of force and moment;
based on the components of the force and the moment, acquiring the speed and the angular speed of the fixed wing aircraft in each direction of the current step length;
integrating the speeds and the angular speeds in all directions, acquiring the displacement and the rotation angle of the fixed wing aircraft in the current step length, and acquiring the current position and the actual attitude angle based on the displacement and the rotation angle.
3. The full-freedom fixed-wing aircraft general simulation method of claim 2, wherein obtaining the control surface adjustment of the fixed-wing aircraft comprises:
acquiring a desired position based on the desired flight trajectory, and randomly setting a desired airspeed;
acquiring a desired attitude angle based on the current position and the desired position;
acquiring an attitude error based on the expected attitude angle and the actual attitude angle;
and acquiring the control surface adjustment quantity of the fixed wing aircraft based on the attitude error.
4. The full-freedom fixed-wing aircraft general simulation method of claim 3, wherein obtaining the throttle adjustment of the fixed-wing aircraft comprises:
and acquiring an airspeed error based on the current airspeed and the expected airspeed, and acquiring the throttle adjustment of the fixed-wing aircraft based on the airspeed error.
5. The full degree-of-freedom fixed wing aircraft general simulation method of claim 4, wherein obtaining the desired attitude angle comprises:
acquiring a position error between the current position and the expected position;
and acquiring the expected attitude angle based on the position error.
6. The full degree-of-freedom fixed wing aircraft general simulation method of claim 5, wherein the desired attitude angle comprises: a desired roll angle and a desired pitch angle;
acquiring the desired attitude angle includes:
decomposing the position error into a heading error in a horizontal plane and an elevation error in a vertical direction;
acquiring the expected roll angle based on the heading error;
and acquiring the expected pitch angle based on the elevation error.
7. The method of claim 6, wherein adjusting the fixed wing aircraft comprises:
adjusting the heading error and the altitude error of the fixed-wing aircraft based on the control surface adjustment;
and adjusting the airspeed error of the fixed-wing aircraft based on the throttle adjustment.
8. The full degree-of-freedom fixed wing aircraft general simulation method of claim 1, wherein planning the desired flight trajectory comprises:
planning a route point, and acquiring an initial expected flight track based on the route point;
and carrying out self-smoothing processing on the initial expected flight trajectory to obtain the expected flight trajectory.
9. The full-freedom fixed-wing aircraft general simulation method of claim 8, wherein performing a self-smoothing process on the initial desired flight trajectory comprises:
acquiring a linear distance d between two adjacent waypoints in the initial expected flight trajectory;
if the straight line distance D is larger than a preset distance threshold D, calculating a D/D value, and rounding up the D/D value to obtain an integer n;
inserting n-1 route points between two adjacent route points, and dividing the route between the two adjacent route points into n parts;
and if the linear distance D between the divided adjacent two waypoints is smaller than the preset distance threshold D, ending the self-smoothing processing.
10. A full degree-of-freedom fixed wing aircraft generic simulation method according to claim 3, wherein setting the desired airspeed comprises:
acquiring an air speed ratio based on the desired airspeed and a standard airspeed; the airspeed ratio is: p=v/Vs, p represents the air speed ratio, vs represents the standard airspeed, V represents the desired airspeed;
when 0< p <1, calculating the position and the posture of the model according to the standard airspeed Vs, multiplying the current position by p for equal-proportion reduction before outputting the current position, and keeping the actual posture angle unchanged;
when p=1, calculating the position and the posture of the model according to the standard airspeed Vs, and normally outputting the current position and the actual posture angle;
when p is more than 1, calculating the position and the gesture of the model according to the standard airspeed Vs, and shortening the time point of external output from t to ta+ (t-ta)/p; the time point of the external output is as follows: the cumulative time after the start of the simulation, ta, represents the time at which the airspeed is changed.
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