CN113835438B - Control method for catapult-assisted take-off of unmanned aerial vehicle - Google Patents
Control method for catapult-assisted take-off of unmanned aerial vehicle Download PDFInfo
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Abstract
The invention discloses a control method for catapult-assisted take-off of an unmanned aerial vehicle, and belongs to the field of unmanned aerial vehicle control; firstly, powering up the unmanned aerial vehicle for standby, keeping the control surfaces in the middle position, and initializing and setting take-off parameters; monitoring a ground station instruction in real time, and controlling the rocket to ignite and enter a first stage of taking off after receiving the instruction to enter a take-off state; judging the ground speed and the airspeed of the unmanned aerial vehicle, and if the ground speed and the airspeed are larger than the set threshold, successfully igniting and entering a second stage; otherwise, the ignition fails, and the take-off process is stopped. Then, judging the current height of the unmanned aerial vehicle in real time, entering a third stage after the current height reaches the safe height, controlling the engine to linearly increase to a climbing throttle, controlling the unmanned aerial vehicle to fly to a first waypoint of a preset task route, and simultaneously starting longitudinal position control, heading position control and heading attitude control; and when the GPS or the measurement and control data link is abnormal, the heading, the altitude and the speed of the unmanned aerial vehicle are regulated and controlled. The invention ensures the reliability of the system and realizes the fully-autonomous take-off process.
Description
Technical Field
The invention belongs to the technical field of unmanned aerial vehicle control, and particularly relates to a control method for catapult-assisted take-off of an unmanned aerial vehicle.
Background
In recent years, while unmanned aerial vehicles rapidly develop, the variety is also more and more abundant, executable tasks are also more and more complex, and unmanned and low-cost advantages make unmanned aerial vehicles more and more important in the military industry.
According to different take-off modes of the unmanned aerial vehicle, the unmanned aerial vehicle is divided into running take-off, hand throwing take-off, catapult take-off and the like, and the advantages and the disadvantages of the unmanned aerial vehicle exist respectively, wherein enough mechanical energy is obtained in a very short time under the action of a booster rocket during the catapult take-off of the unmanned aerial vehicle, so that the unmanned aerial vehicle reaches the safe flying height and speed before the rocket booster falls off, and the unmanned aerial vehicle continues to fly under the action of an engine after the rocket booster falls off. The take-off mode has good maneuverability, can take off smoothly in more complex task environments and take-off environments, has less limit on required take-off fields, and can also carry out transmission take-off on the ground or ships, so that the take-off mode has wide application prospect.
When the unmanned aerial vehicle catapults and takes off, the control of taking off is important, wherein the unmanned aerial vehicle magnetic compass is influenced by magnetic environments such as a catapult frame or an catapult box in the standby and take-off stages before taking off, the magnetic heading precision obtained by the magnetic compass is obviously reduced and even cannot be used, and after taking off, the magnetic compass still needs to be corrected for a period of time to obtain more accurate heading measurement precision. If the takeoff control method is not improved, the flight safety is seriously threatened.
Disclosure of Invention
The invention provides a control method for catapult-assisted take-off of an unmanned aerial vehicle, which aims at the defects of the prior art and is suitable for controlling the unmanned aerial vehicle to take off by one key by a flight control system.
The control method of the catapult-assisted take-off of the unmanned aerial vehicle comprises the steps of igniting a rocket in a first stage; the unmanned aerial vehicle at the second stage climbs to a safe height; and a third stage of entering a first waypoint of the mission route from the safe altitude;
the method comprises the following specific steps:
step one, electrifying an unmanned aerial vehicle A to be launched, loading the unmanned aerial vehicle A into a launching frame for standby, keeping each control surface in a neutral position, and initializing and setting a pitch angle, a roll angle and a course angle of catapult-assisted take-off, a lower limit of flying height and a preset mission course.
Step two, the unmanned plane A monitors the control instruction of the ground station in real time, and enters a take-off state from the ground state after receiving an effective take-off instruction;
thirdly, a flight control system of the unmanned aerial vehicle A sends out a signal to control the rocket to ignite, and the rocket pops up together with the unmanned aerial vehicle A to enter a first stage of taking off;
step four, after the rocket is ignited, the flight control system judges the ground speed and the airspeed of the unmanned aerial vehicle A, and when the ground speed and the airspeed of the unmanned aerial vehicle A are greater than a set threshold value, the rocket is successfully ignited, and the second stage is entered; if the ground speed or airspeed is far below the set threshold after ignition for a period of time, the rocket is considered to fail to ignite, the take-off process is stopped, and the engine is shut down.
In the first stage and the second stage, the rudder of the unmanned aerial vehicle A maintains the middle position, and the longitudinal attitude control and the rolling attitude control are started;
the longitudinal attitude control takes an initial preset take-off pitch angle as input of a PID controller, takes the current pitch angle and pitch angle speed of the unmanned aerial vehicle A as feedback, and calculates and outputs rudder quantity delta of an elevator e Keeping a set take-off climbing angle of the unmanned aerial vehicle A;
rudder amount delta of the output elevator e The calculation formula is as follows:
wherein ,
is pitch angle feedback coefficient>
Is pitch integral coefficient>
Is the pitch angle rate feedback coefficient, θ 0 For the initially set pitch angle, θ is the current pitch angle of the unmanned aerial vehicle a, and q is the current pitch angle rate of the unmanned aerial vehicle a;
the roll attitude control keeps the roll angle of the unmanned aerial vehicle A to be 0 DEG, takes the target roll angle 0 DEG initially set by the unmanned aerial vehicle A as the input of a PID controller, takes the current roll angle and the roll angle speed of the unmanned aerial vehicle A as feedback, and calculates and outputs the rudder delta of the aileron a ；
Output rudder delta of aileron a The calculation formula is as follows:
wherein ,
for roll angle feedback coefficient +.>
For roll angle integral coefficient +.>
Is a roll angle speed feedback coefficient,
for the initially set roll angle +.>
And p is the current roll angle speed of the unmanned aerial vehicle A.
Step five, the flight control system judges the current height of the unmanned aerial vehicle A in real time, when the unmanned aerial vehicle A reaches the safe height, the unmanned aerial vehicle A enters a third stage, the flight control system sends a signal to control the engine to start, the engine throttle is linearly increased from an idle throttle to a climbing throttle, and the unmanned aerial vehicle A is separated from a rocket;
step six, after entering the third stage, the flight control system controls the unmanned aerial vehicle A to fly to the first waypoint of the preset task route, and simultaneously starts longitudinal position control, course position control and course attitude control;
in the third stage, taking the ground speed direction of the unmanned aerial vehicle as a course angle to replace a magnetic course angle; the longitudinal position control is height control, the height of the first waypoint is input by a PID controller, the current height and lifting speed of the unmanned aerial vehicle A are used as feedback, a target pitch angle between the unmanned aerial vehicle A and the first waypoint is calculated, and a longitudinal control loop of cascade PID is formed with longitudinal attitude control;
the altitude control law is expressed as follows:
the heading position control is side offset control, the side offset of the current position of the unmanned aerial vehicle A and the first waypoint is used as the input of a PID controller, the target heading angle between the unmanned aerial vehicle A and the first waypoint is calculated, and then the target heading angle is used as the input of a heading attitude controller, and the rudder amount of the unmanned aerial vehicle A is calculated and output through the PID controller;
the course position control law is shown in the following formula:
wherein ,
is a lateral offset feedback coefficient->
For the side offset integral coefficient, +.>
As the lateral speed feedback coefficient, deltaL is the current lateral offset of the unmanned plane A, v e For the current lateral speed of unmanned aerial vehicle a, ψ c And outputting a target course angle of the unmanned aerial vehicle A for the controller.
The course attitude control law is shown in the following formula:
wherein ,
for course angle feedback coefficient, +.>
For course angle integral coefficient, +.>
As the course angular velocity feedback coefficient, psi is the current course angle of the unmanned aerial vehicle A, r is the current course angular velocity of the unmanned aerial vehicle A, delta r The rudder amount of the unmanned aerial vehicle A is output by the controller.
When each waypoint on the mission route is tracked, the roll outer ring of the unmanned aerial vehicle A inputs the course and the lateral offset from each waypoint, and performs coordinated turning together with course control, and the controller outputs a target roll angle
And then outputting the aileron rudder quantity of the unmanned plane A according to the roll attitude control law.
The roll outer loop control law is shown as the following formula:
wherein ,
is a lateral offset feedback coefficient->
For the side offset integral coefficient, +.>
For lateral velocity feedback coefficient, K YR And the heading angle feedback coefficient.
Step seven, in the third stage, when the GPS or the measurement and control data link is abnormal and the abnormal time is less than the set time, controlling the unmanned aerial vehicle to keep the heading, the altitude and the speed unchanged until the data are normal; otherwise, if the abnormal time exceeds the set time, the unmanned aerial vehicle is controlled to keep the constant angular rate and spiral.
The invention has the advantages that:
(1) According to the control method for the catapult-assisted take-off of the unmanned aerial vehicle, provided by the invention, the workflow and control law output of rocket ignition and engine starting in the take-off section are designed, the reliability of a system is ensured, the fully-autonomous take-off flow is realized, and one-key take-off can be realized through ground station operation;
(2) According to the control method for the catapult-assisted take-off of the unmanned aerial vehicle, the protection threshold values such as the pitch angle, the roll angle and the height are preset in the preparation stage before the take-off of the unmanned aerial vehicle, and the target state values of the unmanned aerial vehicle are controlled to be within the protection threshold values in the flight process, so that the flight safety of the unmanned aerial vehicle is ensured;
(3) According to the control method for the catapult-assisted take-off of the unmanned aerial vehicle, corresponding logic judgment is made for the rocket dumb situation possibly occurring after take-off, so that the loss caused by the dumb situation is reduced to the greatest extent;
(4) The invention discloses a control method for catapult-assisted take-off of an unmanned aerial vehicle, which aims at GPS or communication data link interference possibly occurring in the flight of the unmanned aerial vehicle, and establishes a corresponding control strategy and protection logic;
(5) According to the unmanned aerial vehicle catapult-assisted take-off control method, when magnetic heading measurement of the unmanned aerial vehicle is subjected to magnetic interference and cannot be used, an additional sensor is not needed, the ground speed direction can be measured through the GPS, and the ground speed direction is used as a control algorithm for input, so that unmanned aerial vehicle heading control is realized, and the unmanned aerial vehicle catapult-assisted take-off control method has the advantages of being low in cost and high in reliability.
Drawings
FIG. 1 is a flow chart of a method for controlling the take-off of an catapult-assisted take-off unmanned aerial vehicle according to the invention;
fig. 2 is a flowchart of an unmanned aerial vehicle catapult-assisted take-off in an embodiment of the invention;
fig. 3 is a longitudinal control block diagram of an unmanned aerial vehicle according to an embodiment of the present invention;
fig. 4 is a heading control block diagram of an unmanned aerial vehicle according to an embodiment of the present invention;
fig. 5 is a transverse control block diagram of an unmanned aerial vehicle according to an embodiment of the present invention.
Detailed Description
Specific embodiments of the present invention will be described below with reference to the accompanying drawings.
The invention provides a method for controlling the take-off of an catapult-assisted take-off unmanned aerial vehicle, which comprises the steps of igniting a rocket in a first stage; the unmanned aerial vehicle at the second stage climbs to a safe height; and a third stage of entering a first waypoint of the mission route from the safe altitude;
as shown in fig. 1, the specific steps are as follows:
step one, electrifying an unmanned aerial vehicle A to be launched, loading the unmanned aerial vehicle A into a launching frame for standby, keeping each control surface in a neutral position, and initializing and setting a pitch angle, a roll angle and a course angle of catapult-assisted take-off, a lower limit of flying height and a preset mission course.
The control rudder surface of the unmanned aerial vehicle comprises ailerons, rudders and elevators; the take-off pitch angle is set according to the pitch angle of the ejection frame, the rolling angle is set to be 0 degrees, and the course angle is set to be the standby course angle before take-off; the lower limit of the flying height is the lowest flying height of the unmanned aerial vehicle relative to the ground altitude of an airport when the unmanned aerial vehicle executes a mission route, and the flying safety height of the unmanned aerial vehicle is the ground altitude plus the lower limit of the flying height; the mission route consists of a plurality of waypoints, and each waypoint comprises longitude and latitude, altitude, airspeed and other information;
step two, the unmanned plane A monitors the control instruction of the ground station in real time, and enters a take-off state from the ground state after receiving an effective take-off instruction;
the unmanned plane and the ground station mutually transmit data through a wireless data link;
thirdly, a flight control system of the unmanned aerial vehicle A sends out a signal to control the rocket to ignite, and the rocket pops up together with the unmanned aerial vehicle A to enter a first stage of taking off;
the rocket ignition signal is high-level effective;
step four, after the rocket is ignited, the flight control system judges the ground speed and the airspeed of the unmanned aerial vehicle A, and when the ground speed and the airspeed of the unmanned aerial vehicle A are greater than a set threshold value, the rocket is successfully ignited, and the second stage is entered; if the ground speed or airspeed is far below the set threshold after ignition for a period of time, the rocket is considered to fail to ignite, the take-off process is stopped, and the engine is shut down.
In the first stage and the second stage, the rudder of the unmanned aerial vehicle A maintains the middle position, and the longitudinal attitude control and the rolling attitude control are started; and outputting amplitude limiting through a PID controller, so that the target pitch angle and the target roll angle of the unmanned aerial vehicle do not exceed the set threshold.
The longitudinal attitude control takes an initial preset take-off pitch angle as input of a PID controller, takes the current pitch angle and pitch angle speed of the unmanned aerial vehicle A as feedback, and calculates and outputs rudder quantity delta of an elevator e Keeping a set take-off climbing angle of the unmanned aerial vehicle A;
rudder amount delta of the output elevator e The calculation formula is as follows:
wherein ,
is pitch angle feedback coefficient>
Is pitch integral coefficient>
Is the pitch angle rate feedback coefficient, θ 0 For the initially set pitch angle, θ is the current pitch angle of the unmanned aerial vehicle a, and q is the current pitch angle rate of the unmanned aerial vehicle a;
the roll attitude control keeps the roll angle of the unmanned aerial vehicle A to be 0 DEG, takes the target roll angle 0 DEG initially set by the unmanned aerial vehicle A as the input of a PID controller, takes the current roll angle and the roll angle speed of the unmanned aerial vehicle A as feedback, and calculates and outputs the rudder delta of the aileron a ；
Output rudder delta of aileron a The calculation formula is as follows:
wherein ,
for roll angle feedback coefficient +.>
For roll angle integral coefficient +.>
Is a roll angle speed feedback coefficient,
for the initially set roll angle +.>
And p is the current roll angle speed of the unmanned aerial vehicle A.
Step five, the flight control system judges the current height of the unmanned aerial vehicle A in real time, when the unmanned aerial vehicle A reaches the safe height, the unmanned aerial vehicle A enters a third stage, the flight control system sends a signal to control the engine to start, the engine throttle is linearly increased from an idle throttle to a climbing throttle, and the unmanned aerial vehicle A is separated from a rocket;
the engine start signal is active high; when the unmanned aerial vehicle A reaches the safety height, the rocket ignition signal becomes low;
step six, after entering the third stage, the flight control system controls the unmanned aerial vehicle A to fly to the first waypoint of the preset task route, and simultaneously starts longitudinal position control, course position control and course attitude control;
in the third stage, taking the ground speed direction of the unmanned aerial vehicle as a course angle to replace a magnetic course angle;
the longitudinal position control, namely the height control, is shown in fig. 3, the height of the first waypoint is taken as the input of a PID controller, the current height and the lifting speed of the unmanned aerial vehicle A are taken as the feedback, the target pitch angle between the unmanned aerial vehicle A and the first waypoint is calculated, and a longitudinal control loop of cascade PID is formed with the longitudinal attitude control;
the altitude control law is expressed as follows:
The course position control, namely the lateral offset control, is shown in fig. 4, wherein the lateral offset of the current position of the unmanned aerial vehicle A and the first waypoint is used as the input of a PID controller, the target course angle between the unmanned aerial vehicle A and the first waypoint is calculated and obtained, and then is used as the input of a course gesture controller, and the rudder amount of the unmanned aerial vehicle A is calculated and output through the PID controller;
the course position control law is shown in the following formula:
wherein ,
is a lateral offset feedback coefficient->
For the side offset integral coefficient, +.>
As the lateral speed feedback coefficient, deltaL is the current lateral offset of the unmanned plane A, v e For the current lateral speed of unmanned aerial vehicle a, ψ c And outputting a target course angle of the unmanned aerial vehicle A for the controller.
The course attitude control law is shown in the following formula:
wherein ,
for course angle feedback coefficient, +.>
For course angle integral coefficient, +.>
As the course angular velocity feedback coefficient, psi is the current course angle of the unmanned aerial vehicle A, r is the current course angular velocity of the unmanned aerial vehicle A, delta r The rudder amount of the unmanned aerial vehicle A is output by the controller.
As shown in fig. 5, when tracking each waypoint on the mission course, the roll outer loop of the unmanned plane a inputs the heading and lateral offset from each waypoint, performs coordinated turning together with heading control, and the controller outputs a target roll angle
And then outputting the aileron rudder quantity of the unmanned plane A according to the roll attitude control law.
The roll outer loop control law is shown as the following formula:
wherein ,
is a lateral offset feedback coefficient->
For the side offset integral coefficient, +.>
For lateral velocity feedback coefficient, K YR And the heading angle feedback coefficient.
Step seven, in the third stage, when the GPS or the measurement and control data link is abnormal and the abnormal time is less than the set time, controlling the unmanned aerial vehicle to keep the heading, the altitude and the speed unchanged until the data are normal; otherwise, if the abnormal time exceeds the set time, the unmanned aerial vehicle is controlled to keep the constant angular rate and spiral.
Examples
As shown in fig. 2, the specific flow is as follows:
(1) The unmanned aerial vehicle is powered on, is loaded into a launching frame for standby and ready for take-off, each control surface keeps a median position, a take-off target pitch angle, a target roll angle and a target yaw angle are set in an initialized mode, a flight height lower limit is set, and a mission route is preset.
The unmanned aerial vehicle control rudder surface comprises ailerons, rudders and elevators, the take-off target pitch angle is set according to the pitch angle of the ejection frame, and the take-off target pitch angle is set to 25 degrees, namely the take-off control unmanned aerial vehicle climbs at the pitch angle of 25 degrees; the target rolling angle is set to 0, and the target yaw angle is set to be the standby course angle before taking off; each waypoint of the mission route comprises longitude and latitude, altitude, flying airspeed and other information. The lower limit of the altitude of the unmanned aerial vehicle is the lowest altitude of the unmanned aerial vehicle relative to the altitude of the airport ground when the unmanned aerial vehicle executes the mission route, in the example, the altitude of the airport is about 1400 meters, and the lower limit of the altitude is set to be 90 meters, so that the altitude of the unmanned aerial vehicle when the unmanned aerial vehicle flies is not lower than 1490 meters; the altitude of the first waypoint of the mission route is set to 1600 meters.
(2) After receiving an effective take-off instruction sent by a ground station, the unmanned aerial vehicle enters a take-off state from a ground state, and the flight control system starts to execute a take-off control flow and enters step (3).
The unmanned aerial vehicle and the ground station mutually transmit data through a wireless data link, the unmanned aerial vehicle starts to detect a control instruction of the ground station after being electrified, and the unmanned aerial vehicle automatically enters a take-off process after receiving a take-off instruction;
(3) The specific method of the rocket ignition take-off control flow is as follows:
(3.1) the flight control system sends a path of switching signal to control the rocket to ignite and pop up together with the unmanned aerial vehicle; after the rocket is ignited, the engine accelerator is placed at 30% idle speed; the rocket ignition signal lasts for 2 seconds, so that the unmanned aerial vehicle is ensured to climb to a safe height, and then the rocket ignition signal becomes low;
after receiving a take-off instruction, the flight control system automatically starts timing by a program counter in flight control software and is used for controlling the execution sequence and duration of each subsequent instruction;
after the rocket is ignited and taken off, the unmanned aerial vehicle rudder keeps the middle position, and the longitudinal attitude control and the rolling attitude control are started.
The target pitch angle controlled by the longitudinal attitude is kept to be 25 degrees, the target pitch angle of the unmanned aerial vehicle is input by taking the target pitch angle of the unmanned aerial vehicle as a PID controller, and the rudder quantity of the elevator is calculated and output by the controller, so that the unmanned aerial vehicle can keep a take-off climbing angle of 25 degrees and can smoothly reach a safe height; the roll attitude control takes a target roll angle 0 degree of the unmanned aerial vehicle as the input of a PID controller, and calculates and outputs the rudder quantity of the aileron through the controller, so that the roll angle is kept to be 0 degree in the process of taking off and ejecting the unmanned aerial vehicle, and the pneumatic performance of the unmanned aerial vehicle is prevented from being deteriorated or a transverse velocity component is prevented from being generated due to the roll;
after the rocket is ignited and taken off, the flight control system judges the ground speed and the airspeed of the unmanned aerial vehicle in real time, when the ground speed of the unmanned aerial vehicle is greater than 5m/s and the airspeed is greater than 10m/s, the rocket is successfully ignited, otherwise, the rocket is considered to be failed to be ignited, the take-off process is stopped, and the engine is shut down.
(3.2) when the rocket is ignited, the unmanned aerial vehicle climbs under the boosting of the rocket, meanwhile, the flight control system judges whether the current height of the unmanned aerial vehicle reaches the safe height in real time, namely whether the current flight height is larger than the lower limit 1490 m of the flight height, when the current height of the unmanned aerial vehicle is larger than the lower limit 1490 m of the flight height and lasts for more than 1 second, the flight control system sends a switch signal to control the engine to start, the start signal lasts for 5 seconds, the accelerator is increased from 30% to 80% after the engine is started, the accelerator is increased in a mode of softening instructions, the linear increase is performed within 2 seconds, and then the engine start signal becomes lower;
and (3.3) after the engine is started, the flight control system controls the unmanned aerial vehicle to fly to a first target navigation point of a preset mission route, and simultaneously starts course attitude control and outer ring position control, wherein the outer ring position control comprises longitudinal position control and course position control.
In the steps (3.1) and (3.2), rocket ignition signals and engine starting signals sent by the flight control system are high-level effective;
in the step (3.3), longitudinal position control, namely height control, is input by taking the target height of the unmanned aerial vehicle as a PID controller, and the target pitch angle is calculated and output by the controller, so that a longitudinal control loop of cascade PID is formed with longitudinal attitude control; in the embodiment, after the target waypoint is switched, the altitude gradient control is executed, namely the unmanned aerial vehicle is controlled to execute the altitude control by the oblique line formed by the current point and the target waypoint;
in the step (3.3), course position control, namely lateral offset control, is performed, so that the course tracking precision of the unmanned aerial vehicle is ensured; the position control takes the lateral offset of the current position of the unmanned aerial vehicle and the target waypoint as the input of a PID controller, and the target course angle is calculated by the controller; the target course angle is used as the input of the course attitude controller, and the PID controller calculates and outputs rudder amount;
in the step (3.3), when tracking a target course, the unmanned plane roll attitude control and the course control together perform coordinated turning, the controller inputs the deviation of the course and the lateral deviation, outputs a target roll angle through the PID controller, and then outputs the aileron rudder quantity in the roll attitude control (3.1).
In the step (3.3), because the unmanned aerial vehicle is subjected to ferromagnetic interference, the work of the magnetic compass on the unmanned aerial vehicle is interfered by the magnetic field of the soft magnet, so that the magnetic heading angle measured by the magnetic compass has larger deviation and even cannot be used, and the magnetic heading angle can be recovered to be normal after the unmanned aerial vehicle takes off, in the example, the unmanned aerial vehicle takes the heading angle direction, namely the ground speed direction, as the heading angle in the take-off section of the unmanned aerial vehicle to replace the heading angle of the magnetic compass; after the unmanned aerial vehicle takes off, judging the ground speed of the unmanned aerial vehicle in real time, and taking the ground speed direction of the unmanned aerial vehicle as a course angle after the local speed is greater than 5 m/s;
the following protections are performed while step (3.3) is performed:
(a) The unmanned plane executes pitch angle protection and roll angle protection to prevent overlarge pitch angle and roll angle in flight, so that the aircraft stalls;
the specific operation is as follows: outputting amplitude limiting through a controller, so that the target pitch angle and the target roll angle of the unmanned aerial vehicle do not exceed a set threshold;
(b) After the unmanned aerial vehicle reaches the safe height, the unmanned aerial vehicle executes height protection, and the target height for controlling the unmanned aerial vehicle to fly is not lower than the lower limit 1490 m;
(c) The unmanned aerial vehicle performs communication interrupt protection: if GPS or measurement and control data link is abnormal in flight, if abnormal time is less than 5 minutes, controlling the unmanned aerial vehicle to keep the heading, the altitude and the speed unchanged until the data is recovered to be normal; and if the abnormal time exceeds 5 minutes, controlling the unmanned aerial vehicle to maintain the constant angular rate spiral.
Claims (2)
1. The control method for the catapult-assisted take-off of the unmanned aerial vehicle is characterized by comprising the following steps of:
step one, electrifying an unmanned aerial vehicle A to be launched, loading the unmanned aerial vehicle A into a launching frame for standby, keeping the control surfaces in the middle position, and initializing and setting a pitch angle, a roll angle and a course angle of catapult-assisted take-off, a lower limit of flying height and a preset mission course;
step two, the unmanned plane A monitors the control instruction of the ground station in real time, and enters a take-off state from the ground state after receiving an effective take-off instruction;
thirdly, a flight control system of the unmanned aerial vehicle A sends out a signal to control the rocket to ignite, and the rocket pops up together with the unmanned aerial vehicle A to enter a first stage of taking off;
step four, after the rocket is ignited, the flight control system judges the ground speed and the airspeed of the unmanned aerial vehicle A, and when the ground speed and the airspeed of the unmanned aerial vehicle A are greater than a set threshold value, the rocket is successfully ignited, and the second stage is entered; if the ground speed or airspeed is far lower than the set threshold after ignition for a period of time, the rocket is considered to fail to ignite, the take-off process is stopped, and the engine is shut down;
step five, the flight control system judges the current height of the unmanned aerial vehicle A in real time, when the unmanned aerial vehicle A reaches the safe height, the unmanned aerial vehicle A enters a third stage, the flight control system sends a signal to control the engine to start, the engine throttle is linearly increased from an idle throttle to a climbing throttle, and the unmanned aerial vehicle A is separated from a rocket;
step six, after entering the third stage, the flight control system controls the unmanned aerial vehicle A to fly to the first waypoint of the preset task route, and simultaneously starts longitudinal position control, course position control and course attitude control;
in the third stage, taking the ground speed direction of the unmanned aerial vehicle as a course angle to replace a magnetic course angle; the longitudinal position control is height control, the height of the first waypoint is input by a PID controller, the current height and lifting speed of the unmanned aerial vehicle A are used as feedback, a target pitch angle between the unmanned aerial vehicle A and the first waypoint is calculated, and a longitudinal control loop of cascade PID is formed with longitudinal attitude control;
the altitude control law is expressed as follows:
the heading position control is side offset control, the side offset of the current position of the unmanned aerial vehicle A and the first waypoint is used as the input of a PID controller, the target heading angle between the unmanned aerial vehicle A and the first waypoint is calculated, and then the target heading angle is used as the input of a heading attitude controller, and the rudder amount of the unmanned aerial vehicle A is calculated and output through the PID controller;
the course position control law is shown in the following formula:
wherein ,
is a lateral offset feedback coefficient->
For the side offset integral coefficient, +.>
As the lateral speed feedback coefficient, deltaL is the current lateral offset of the unmanned plane A, v e For the current lateral speed of unmanned aerial vehicle a, ψ c The target course angle of the unmanned aerial vehicle A is output by the controller;
the course attitude control law is shown in the following formula:
wherein ,
for course angle feedback coefficient, +.>
For course angle integral coefficient, +.>
As the course angular velocity feedback coefficient, psi is the current course angle of the unmanned aerial vehicle A, r is the current course angular velocity of the unmanned aerial vehicle A, delta r The rudder amount of the unmanned aerial vehicle A is output by the controller;
when each waypoint on the mission route is tracked, the roll outer ring of the unmanned aerial vehicle A inputs the course and the lateral offset from each waypoint, and performs coordinated turning together with course control, and the controller outputs a target roll angle
Then outputting the aileron rudder quantity of the unmanned plane A according to a roll attitude control law;
the roll outer loop control law is shown as the following formula:
wherein ,
is a lateral offset feedback coefficient->
For the side offset integral coefficient, +.>
For lateral velocity feedback coefficient, K YR The heading angle feedback coefficient;
step seven, in the third stage, when the GPS or the measurement and control data link is abnormal and the abnormal time is less than the set time, controlling the unmanned aerial vehicle to keep the heading, the altitude and the speed unchanged until the data are normal; otherwise, if the abnormal time exceeds the set time, the unmanned aerial vehicle is controlled to keep the constant angular rate and spiral.
2. The method for controlling catapult-assisted take-off of an unmanned aerial vehicle according to claim 1, wherein in the fourth step, in the first and second stages, the rudder of the unmanned aerial vehicle a maintains a neutral position, and the longitudinal attitude control and the roll attitude control are started;
the longitudinal attitude control takes an initial preset take-off pitch angle as input of a PID controller, takes the current pitch angle and pitch angle speed of the unmanned aerial vehicle A as feedback, and calculates and outputs rudder quantity delta of an elevator e Keeping a set take-off climbing angle of the unmanned aerial vehicle A;
rudder amount delta of the output elevator e The calculation formula is as follows:
wherein ,
is pitch angle feedback coefficient>
Is pitch integral coefficient>
Is the pitch angle rate feedback coefficient, θ 0 For the initially set pitch angle, θ is the current pitch angle of the unmanned aerial vehicle a, and q is the current pitch angle rate of the unmanned aerial vehicle a;
the roll attitude control keeps the roll angle of the unmanned aerial vehicle A to be 0 DEG, takes the target roll angle 0 DEG initially set by the unmanned aerial vehicle A as the input of a PID controller, takes the current roll angle and the roll angle speed of the unmanned aerial vehicle A as feedback, and calculates and outputs the rudder delta of the aileron a ；
Output rudder delta of aileron a The calculation formula is as follows:
wherein ,
for roll angle feedback coefficient +.>
For roll angle integral coefficient +.>
For roll angle speed feedback coefficient, +.>
For the initially set roll angle +.>
And p is the current roll angle speed of the unmanned aerial vehicle A. />
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