Control system and launching method of air-based mounting launching folding wing unmanned aerial vehicle

Abstract

The invention discloses a control system and a launching method of an air-based mounting launching folding wing unmanned aerial vehicle, before a sub-aircraft is thrown and launched, a master aircraft sends a sub-aircraft voltage signal to be continuously monitored by a sub-aircraft flight controller, after a throwing moment is entered, the master aircraft is powered off, an unlocking device is opened, and the sub-aircraft flight controller starts to monitor the voltage for a period of time after the voltage disappears; and at the moment, the V tail controls pitching and participates in rolling control. After a certain period of time, the flight control controls the locking steering engine to unlock, so that the wings start to be unfolded until the wings are unfolded in place, at the moment, the ailerons participate in control, and an unpowered diving pull-up control stage is entered; after a certain period of time, the wings are controlled to be locked. And then flight control judges that the attitude is stable and the air speed is stable, the engine is started after the attitude and the air speed are stable, the rotating speed of the engine is judged, if starting fails, starting operation is repeated for three times, after the engine is started, an air route task is normally carried out, the ground station throwing process is quitted, and normal flight control logic is entered. By means of the method, air-based launching folding wing unmanned aerial vehicle full-process control can be achieved.

Description

Technical Field

[0001] The present invention belongs to the field of unmanned aerial vehicle control, and in particular relates to a control system and a launching method for an air-based mounted launching folding-wing unmanned aerial vehicle. Background Art

[0002] Nowadays, drones are limited by their own software, hardware, and design conditions, and have limitations in certain application environments. For a single drone, small drones cannot perform missions thousands of kilometers away due to insufficient fuel and short range. When using large drones, the high cost and high risk are taken into consideration, so the concept of mother-child cooperation came into being. This model uses a large unmanned (manned) drone with a long flight time and long range as the mother aircraft of the system, and 1 to 2 small drones are mounted under the aircraft as sub-aircraft. When the mother aircraft carries the sub-aircraft and flies within the combat range of the sub-aircraft, the mounting device is opened to launch the sub-aircraft from the air. After the sub-aircraft is launched, it starts to control its own folding mechanism to restore the normal flight body; it turns on normal flight control, controls the attitude, and stabilizes the track. After the sub-aircraft performs the mission, it is mostly recovered by parachute recovery, net capture recovery, etc., or directly uses disposable sub-aircraft such as cruise missiles.

[0003] The mode of dropping sub-drones from mother-and-child drones and sub-drones participating in combat has greatly increased the combat range of small drones, making it possible for a large number of small drones to participate in long-distance reconnaissance and strike missions, greatly reducing the cost of long-distance combat. At the same time, small drones participating in combat missions also have the advantages of high concealment. The technology of sub-drone mounting is also relatively mature. The mounted sub-drones are often designed with a wing folding mechanism. When in the mounted state, the integrated wing will rotate 90° and be located below the fuselage parallel to the fuselage. It looks like a normal mounted missile. This design also greatly reduces the flight resistance of the mother-and-child drone during flight. Since a mother aircraft can mount multiple sub-drones, multiple mother aircraft can release sub-drones at the same time when performing a mission, which can form cluster communication between sub-drones and use cluster methods to carry out saturation strikes, greatly improving the success rate of the mission.

[0004] The close integration of medium and large drones with small and micro drones overcomes their respective limitations. This combination can fully utilize the powerful firepower and long endurance of medium and large drones, while taking advantage of the flexibility and maneuverability of small and micro drones. Medium and large drones can carry more ammunition and equipment and can perform more complex and decisive tasks, while small and micro drones can provide real-time intelligence on the battlefield, conduct reconnaissance and strike enemy targets. The advantage of this combination is that it can complete a wider range of tasks and combat needs by utilizing the complementary characteristics of various types of drones.

[0005] The airborne launch control of the sub-machine can be divided into the control logic at the time of jettisoning and the control method of the sub-machine after normal start-up. After normal start-up, the initial attitude of the aircraft may be more complicated, and the three-axis angles and three-axis angular velocities are irregular, and the classic PID control algorithm is often used. In the control logic at the moment of jettisoning, in order to prevent the sub-machine from colliding with the mother machine after the sub-machine is unlocked, the sub-machine often does not start control immediately. In this way, the sub-machine and the mother machine will maintain a safe height difference, and the recovery of the sub-machine wing folding mechanism can also be completed during this period. It can be seen that a reasonable construction of a set of timing logics for unhooking, sub-machine wing popping, sub-machine driving, sub-machine unpowered gliding start-up, and sub-machine powered start-up is the key to safely completing the jettisoning process of the mother-and-child aircraft. Among the existing casting control methods, there is a control method for casting a quad-rotor UAV, which adopts a PID control algorithm and a fuzzy control method based on this technology; some existing methods also design a set of aircraft platform mission processes, and the unmanned sub-machine's mission execution process is mainly divided into an on-hook stage, a descent and deployment, a mission stage, and a recovery / self-destruction stage. The key descent and deployment stage is that the unmanned sub-machine opens the parachute and lands at a predetermined position after being dropped, unfolds the rotor after stabilizing its posture, and starts controllable powered flight after taking off the parachute. Summary of the invention

[0006] In view of the above problems, the present invention proposes a control system and a launching method for an air-based mounted launch of a folding-wing UAV. In addition to normal control of the UAV flight, the present invention designs a launch process for air-based launch of the UAV. Secondly, for each link of the air-based launch process, the control timing and time interval are designed to ensure the stability and safety of the air-based launch, the control method and control law of each link are designed, and the protection logic in the air-based launch process is designed. These are written into the flight control hardware to complete the design of the full-process flight control system.

[0007] The control system of the air-based mounted launch folding-wing UAV of the present invention comprises a folding-wing V-tail layout UAV, a mounting mother machine, a flight control and navigation system module, a ground station module, air-based launch flight control software, a rack hook, etc.

[0008] The detailed steps of the technical solution of the control system and launching method of the air-based mounted launching folding-wing UAV of the present invention are as follows:

[0009] Step 1: The mother machine continuously supplies a voltage signal to the daughter machine as the signal voltage for airborne transmission.

[0010] Step 2: The ground terminal confirms that the conditions for delivery are met and sends a delivery signal to the host machine, which enters the delivery state;

[0011] Step 3: The slave aircraft flight control continuously monitors the voltage signal sent by the master aircraft in step 1.

[0012] Step 4: The operator of the main machine cuts off the voltage signal, the locking device of the main machine is unlocked, the hook is opened, and the sub-machine is launched;

[0013] Step 5: The slave aircraft flight control ADC detects the voltage signal. If the monitored voltage signal is 0 for a certain period of time, it means that it has been separated from the mother aircraft. The current time is recorded as T0 and the process goes to step 6.

[0014] Step 6: The control surfaces of the tail wing of the sub-aircraft begin to be controlled, and the roll attitude of the aircraft in the folded state is adjusted by deflecting the control surfaces of the tail wing to suppress the lateral roll of the folded body.

[0015] Step 7. After a period of time from time T0, it is time T1; at time T1, the flight control sends a command to the wing lock servo, the wing lock servo opens, and controls the wings to start rotating and unfolding.

[0016] Step 8: After the wing lock servo is turned on, it takes a while to reach the moment T2, at which time the wings are fully deployed and the ailerons intervene to control and stabilize the attitude of the sub-aircraft; after the wings are fully deployed, it takes a while to reach the moment T3', at which time the flight control sends a command to the wing lock servo, and the wing lock servo locks the wings.

[0017] Step 9. After the wings are fully deployed, the sub-machine enters the unpowered gliding stage. At this time, the sub-machine dives at high speed and is pulled up and controlled by unpowered dive. After a period of time, the attitude is stable, and the attitude stabilization time is T3; if the height of the sub-machine is lower than the minimum parachute opening height, the parachute is opened and landed; if the height of the sub-machine is not lower than the minimum parachute opening height after the attitude is stable, proceed to step 10.

[0018] Step 10: At T3, the flight control gives the engine start command to determine whether the engine has started. The engine start completion time is recorded as T4. If the engine is detected to be not started, it will restart after an interval of 2 seconds. If the engine fails to start 3 times and the height of the sub-machine is lower than the minimum parachute opening height, the parachute will be opened for landing. If the height is greater than the minimum parachute opening height, the unpowered glide will continue. During the glide, the engine will be started by the ground station. If the start fails and the height of the sub-machine is lower than the minimum parachute opening height, the parachute will be opened for landing.

[0019] Step 11. After the engine is started, exit the air-based launch process and the aircraft enters the mission phase.

[0020] Step 12: Use the traditional control laws in the air-based launch flight control module to carry out normal route missions until parachute recovery.

[0021] In the above-mentioned air-based launch method of the folding-wing UAV, protection logic is designed in the stages of throwing and pulling up the sub-machine to ensure the safety of air-based launch, including:

[0022] (1) Engine start failure protection

[0023] When the engine fails to ignite three times, the engine start failure protection logic is entered; at this time, the UAV will no longer start the engine and start to glide without power. The target waypoint of the glide is the home point. At this time, the home point is located at the initial point of the start of the casting, but the height is 150m. After reaching the home point, it starts to circle around the home point and waits for the next instruction from the ground station; during the entire protection period, the ground station is used to issue manual ignition instructions, or switch to semi-autonomous mode and use the remote control to manually control the UAV; if the engine is still not successfully started, during the circling and descending process, if it is below the height protection line, the height protection is triggered and the UAV opens the parachute to land.

[0024] (2) Forced pull up

[0025] When the altitude of the UAV during the pull-up control process reaches 800m, and the flight control determines that the UAV attitude has not yet reached stability, it starts to force the pull-up, the engine starts, and switches to the pitch channel control law under the normal flight state, with a target pitch angle of 0°.

[0026] (3) Posture protection

[0027] In the normal flight state of the sub-machine, if the sub-machine pitch is greater than 70° and roll is greater than 90°, and it is not corrected within 4 seconds, the attitude protection of the drone will be triggered. The flight control assumes that the drone is out of control at this time and will issue a parachute opening command;

[0028] (4) High protection

[0029] When the drone's altitude is lower than 100m, the altitude protection is triggered and the drone opens its parachute to land.

[0030] The timing logic of the above-mentioned air-based launch method of the folding-wing UAV is:

[0031] Sequence 1: When detecting the separation signal, the ADC detects that the voltage becomes 0V, and continuously detects the separation signal for 200ms to prevent misjudgment caused by voltage instability. The separation signal is continuously detected for 200ms, and the current time when the separation is detected is recorded as T0. At this time, the control is started, and the attitude of the aircraft in the folded state is adjusted through the tail rudder.

[0032] Sequence 2: unfold the wings. The moment T1 is 300ms after the detachment is detected. At this time, the flight control sends a command to the wing lock servo. The servo turns on and the wings start to rotate and unfold. T1 = T0 + 300ms.

[0033] Timing three: Lock the wings. 1300ms after the servo is turned on, it is time T2. At this moment, the wings are fully unfolded, T2=T1+1300ms. After the wings are fully unfolded, it takes 500ms to reach time T3', T3'=T2+500ms. The flight control gives the wing lock servo command, and the servo locks the wings.

[0034] Sequence 4: After the wings are fully deployed, the aircraft enters the unpowered gliding stage. After Nms, the attitude is considered stable, N = 5s~20s; at this time, if the altitude is lower than the minimum parachute opening altitude, the parachute will be opened for landing.

[0035] Sequence 5: At T3, the flight control gives the engine start command, T3 = T2 + Nms; 3.3s later, it is determined whether the engine has started, that is, the speed is greater than 2000rpm for 3 seconds to prevent the wind from blowing the blades to rotate at high speed instantly and causing misjudgment. The start completion time is recorded as T4; if it is detected that it has not started, it will restart after an interval of 2s.

[0036] Sequence 6: When the engine is started, the aircraft enters the mission phase after the attitude stabilizes. If the engine is started successfully once, T4 = T3 + 3300ms, otherwise T4 is calculated based on the actual number of ignitions and time.

[0037] The advantages of the present invention are:

[0038] (1) The control system and launch method for an air-based mounted launch of a folding-wing UAV provided by the present invention provide a larger combat radius for the patrol vehicle. Compared with the traditional throwing method, the air-based launch process and control method can stably and safely complete the airdrop mission, and have been verified by flight tests.

[0039] (2) The present invention provides a control system and a launch method for an air-based mounted launch of a folding-wing UAV, and designs a set of reasonable air-based launch processes and timing logic, which to a large extent ensure the safety of the mother and child aircraft and the attitude stability of the child aircraft during the launch process.

[0040] (3) The present invention provides a control system and a launching method for an air-based mounted launch of a folding-wing UAV, which specifically designs a control method for two control stages: folded tail wing attitude adjustment control and gliding pull-up control, so that the flight in the throwing stage is safer and more stable. The modified protection logic also allows the sub-machine to adapt to the needs of the throwing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a flow chart of the air-based launch method of a folding-wing UAV according to the present invention;

[0042] Figure 2 This is a schematic diagram of the mother-and-child aircraft during the launch process of the air-based mounted launch of the folding-wing UAV of the present invention;

[0043] Figure 3 The present invention discloses a launch timing logic diagram of a method for launching an air-based mounted folding-wing UAV. DETAILED DESCRIPTION

[0044] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0045] The control system of the air-based mounted launch folding-wing UAV of the present invention comprises a folding-wing V-tail layout UAV, a mounting mother machine, a flight control and navigation module, a ground station module, an air-based launch flight control module, a hook and a hook ring.

[0046] The belly of the mounting mother aircraft is equipped with a hook, and the upper part of the fuselage of the child aircraft is equipped with two longitudinally arranged hook rings. When on the ground, the hook is connected to the hook ring, and the mother and child aircraft are locked; when arriving at the air-based launch site, the mother aircraft sends a casting command (voltage signal) to the flight control of the child aircraft, and at the same time, the hook on the belly of the mother aircraft is released, and the child aircraft is launched, performing a quasi-horizontal throwing motion. The flight control and navigation module is installed on the child aircraft, responsible for the communication between the child aircraft and the mother aircraft, and between the child aircraft and the ground station. The child aircraft is equipped with an air-based launch flight control module to ensure the successful air-based launch of the child aircraft and stable and normal flight. The ground station module is responsible for communication with the flight control, sending command signals, and observing the aircraft status.

[0047] The aforementioned air-based launch flight control module is the design core of this patent, including the launch control part of the air-based launch UAV and the launch timing logic part of the air-based launch UAV, the launch process control law part of the air-based launch UAV, the traditional control law part and the protection logic part.

[0048] Based on the air-based launch flight module, a launch control method for an air-based mounted launch of a folding-wing UAV is implemented, such as Figure 1 , Figure 2 As shown, the details are as follows:

[0049] Step 1: Preparation before leaving:

[0050] The mother aircraft continuously supplies a DC28V voltage signal to the sub-aircraft as the signal voltage for airborne transmission. During the idle flight phase, you need to manually click the release button in the ground station to send a release signal to the mother aircraft and enter the release state. Only then can the mother aircraft proceed with the subsequent release process, avoiding misjudgment caused by voltage signal fluctuations. When the release state is not entered, the flight control of the sub-aircraft will not monitor the voltage and will not enter the release control process.

[0051] Step 2: Confirmation of delivery:

[0052] The ground end confirms that the conditions for delivery are met (all equipment is in normal status and the separation signal is normal), manually clicks the delivery button in the ground station, sends a delivery signal to the mother machine, and enters the delivery state.

[0053] Step 3: Voltage monitoring:

[0054] The flight control of the slave aircraft continuously monitors the DC28V voltage (range 0-36V) and does not start the release process if it does not receive the arming command.

[0055] Step 4: Sub-machine placement:

[0056] The operator of the main machine presses the disengagement button (cuts off the DC28V voltage), the locking device of the main machine is unlocked, the hook opens, and the sub-machine is released.

[0057] Step 5: Detect the separation signal:

[0058] The slave aircraft flight control ADC detects the separation signal, that is, the voltage changes from 28V to 0V (from presence to absence), and continues to detect the separation signal for a period of time to determine that the voltage signal has been cut off and the slave aircraft has been separated from the mother aircraft.

[0059] Step 6: Folding tail wing attitude control:

[0060] When the separation signal is continuously detected to the set time, the current time is recorded as T0. At this time, the control surface of the tail wing of the sub-machine begins to control, and the roll attitude of the folded aircraft is adjusted by deflecting the tail wing control surface to suppress the lateral roll of the folded body.

[0061] Step 7: Unfold the wings:

[0062] After the slave aircraft is confirmed to be detached at time T0, a period of time passes to time T1, at which time the flight control sends a command to the wing lock servo, the wing lock servo opens, and controls the wings to start rotating and unfolding.

[0063] Step 8: Lock the wings:

[0064] After a period of time, the wing lock servo is turned on, which is the moment T2. At this moment, the wing is fully deployed, and the aileron intervenes to control the attitude of the sub-machine. After the wing is fully deployed, after a period of time, it is the moment T3'. At this moment, the flight control sends a command to the wing lock servo, and the wing lock servo locks the wing.

[0065] Step 9: Unpowered gliding:

[0066] After the wings are fully deployed, the sub-machine enters the unpowered gliding stage. At this time, the sub-machine dives at high speed and is pulled up by unpowered dive control. After a period of time, the attitude is stable, and the attitude stability time is T3; the stability condition is determined by the flight control, mainly including the three-axis attitude and airspeed judgment conditions; if the height of the sub-machine is lower than the minimum parachute opening height, the parachute is opened and landed. If the height of the sub-machine is not lower than the minimum parachute opening height after the attitude is stable, proceed to step ten.

[0067] Step 10: Start the engine:

[0068] At T3, the flight control gives the engine start command to determine whether the engine has started (speed> 2000rpm), and the engine start completion time is recorded as T4; if it is detected that the engine has not started, it will restart after an interval of 2s; if the engine fails to start 3 times and the height of the sub-machine is lower than the minimum parachute opening height, the parachute will be opened and landed. If the height of the sub-machine is greater than the minimum parachute opening height, it will continue to glide without power. During the gliding process, the engine will be started by the ground station. If the start fails and the height of the sub-machine is lower than the minimum parachute opening height, the parachute will be opened and landed.

[0069] Step 11. After the engine is started, exit the air-based launch process and the aircraft enters the mission phase.

[0070] Step 12: Use the traditional control laws in the air-based launch flight control module to carry out normal route missions until parachute recovery.

[0071] During the above control method, from the start of the airborne launch of the sub-machine to the complete opening of the wings, the sub-machine of the drone is in a wing folded state or a "semi-folded state" being unfolded. Due to the lack of lateral roll damping brought by the wings, the lateral stability of the drone is poor. Once the side wind causes lateral force and torque, the drone will have a large roll angle and roll angular velocity, which is not conducive to control after the wings are unfolded, and it is possible to cause the drone to enter an unstable mode or attitude divergence. Since the present invention adopts a folding wing V-tail layout drone, the tail of the drone adopts a "V-tail" layout, and the tail is at an angle of 30° to the horizontal direction. When the two tails are differential, the lift on one side of the tail increases and the lift on the other side decreases. Decomposed in the horizontal direction, similar to the aileron, a certain roll torque can be provided to suppress the roll of the drone in the "folded state" and maintain the stability of the roll direction. Therefore, the present invention designs a folding tail attitude control method, in which the folding tail participates in the attitude control, and by allocating a part of the stroke of the "V-tail", an additional roll torque is generated differentially to suppress the lateral roll.

[0072] The rudder travel of the tail of the folding wing V-tail layout drone is plus or minus 15°. When the tail is adjusted, the tail also needs to be controlled in pitch to maintain stability in the pitch direction. However, after the drone is thrown, it first takes a head-down dive flight mode, waits for the wings to be fully unfolded, and then pulls up, so it does not need too much pitch torque to maintain level flight. Therefore, the design of the present invention adopts a 5° V-tail rudder travel to control pitch, and the control logic is the normal control logic. The 10° V-tail rudder travel is used to control roll, and the inner loop PID control is adopted. The target control amount is the target roll angle of the drone Φ a and the current roll angle of the drone Φ c The difference between the two is due to the target roll angle Φ of the drone at this stage. a It is always 0°, so the target control amount is also the UAV roll angle Φc , perform PID link operation on the control quantity, and finally obtain the V tail differential steering quantity δ r1 The control law is as follows:

[0073]

[0074] in, is the gain link control parameter, is the integral link control parameter, is the differential link gain.

[0075] The start time of the above-mentioned folded tail attitude control is the launch time of the drone submachine, that is, T0, when the flight control receives the disappearance of the AD28V voltage. At this time, the mother and submachine are separated, and the submachine performs a quasi-parallel motion, and the V-tail starts to control and suppress roll. The end time of the folded tail attitude control is the moment when the wing is fully unfolded, that is, T2, at which time the submachine aileron starts to control, and the conventional control method is used to control the lateral stability of the drone. At the same time, the V-tail control logic is transformed into the normal control logic to control the heading and pitch.

[0076] During the above control method, the pitch channel control method adopted in the unpowered dive and pull-up control link is the pitch-airspeed closed-loop control, and the roll channel is kept at 0°. Since the initial speed of the UAV is 55m / s, and the cruising speed of the UAV is 50m / s, after the air-based launch, the UAV will dive down for a short period of time. At the beginning of the unpowered dive and pull-up control, the flight state of the UAV is a large angle, high-speed head-down dive, so the pitch-airspeed closed-loop control is adopted, and the airspeed is controlled by controlling the elevator surface, so that the UAV raises its head and slows down, and finally achieves the stability of the pitch attitude and airspeed. The present invention designs a set of attitude stability judgment logic, and after stabilization, the flight control automatically determines whether it has reached a stable state. After reaching a stable state, the flight control sends an engine ignition command. The starting time of the unpowered dive and pull-up control stage is the time when the wings are fully unfolded and the ailerons are controlled; the end time is the time when the flight control determines that the attitude of the UAV is stable and the engine is started for the first time. The pitching control in the present invention is different from the pitching channel control in the normal control mode, and adopts a set of independent control laws and new control parameters, which are specifically:

[0077] The various physical quantities and control parameters in the unpowered dive and pull-up control stage are:

[0078] The pull-up phase indicator temp: temp shows 2 for pull-up preparation; shows 1 for pull-up in progress; shows 0 for pull-up completion;

[0079] Pitch control airspeed proportional coefficient The default value is 2.

[0080] Pitch control airspeed integral coefficient Default 0.1;

[0081] The initial value of the UAV speed V0 measured at the beginning of the pull-up control;

[0082] The speed V of the drone at the moment measured during the pull-up phase;

[0083] Given the final target speed value V c : Cruising speed 50m / s;

[0084] Given the initial speed offset ΔV;

[0085] Exponential transition time constant T: default is 2s;

[0086] Target speed V in the pull-up control phase tar : A function that changes exponentially with time T, with the initial time being V0+ΔV and the final time being V c ;

[0087] The following table summarizes the various state quantities and control parameters in the pull-up control stage:

[0088] Table 1: Table of various state quantities and control parameters in the pull-up control stage

[0089]

[0090]

[0091] The above pitch-airspeed closed-loop control uses the PI link to control the airspeed stability of the UAV. The control law is as follows:

[0092]

[0093] Get the elevator amount δ of the UAV in the pull-up control phase e_pull , used to control speed stability and pitch angle stability.

[0094] During the above control method, the present invention also designs a flight control attitude stability judgment logic, which is used as a command signal for engine start. The judgment logic for flight control attitude stability is: the pull-up is determined to be complete only when the current pitch is within ±12 degrees, the roll angle is within ±10 degrees, and the current airspeed is within the set airspeed (i.e., the cutoff airspeed) value ±3. The engine start is started at this time. In the present invention, during the air-based launch phase of the drone sub-machine, the flight state and flight logic are different from the normal flight state, and some conventional protection logics are not applicable. Therefore, the present invention also designs a series of protection logics during the sub-machine throwing and pulling-up phases, such as altitude protection and forced pull-up, to ensure the safety of air-based launch.

[0095] (1) Engine start failure protection

[0096] In the launch control method of the present invention, after the flight control determines that the attitude of the drone is stable, the engine will be ignited and started. After ignition, the flight control determines the propeller speed. If the ignition fails, a secondary ignition will be performed, and a total of three ignitions will be performed. Due to the influence of factors such as altitude, temperature, and airspeed, the success rate of high-altitude ignition is lower than that of ground ignition. Once the three ignitions fail, the engine start failure protection logic is entered. At this time, the drone no longer starts the engine and starts to glide without power. The target waypoint of the glide is the "home" point. At this time, the "home" point is located at the initial point of the start of the throw, but the height is 150m. After reaching the "home" point, it starts to hover around the home point and wait for the next instruction from the ground station. During the entire protection period, the ground station can be used to perform manual ignition instructions, or it can be switched to semi-autonomous mode and the drone can be manually controlled by remote control. If the engine is not successfully started, during the circling and descending process, if it is lower than the height protection line, the height protection is triggered and the drone opens the parachute to land.

[0097] (2) Forced pull up

[0098] After the wings are fully extended, the initial state of the aircraft is a nose-down dive attitude. At this time, the engine is not started, and it begins to glide without power. At the same time, the elevator controls the drone to slowly pull up. The control law of the pull-up process is independent of the control law of the pitch channel of the drone under normal circumstances. If the pull-up process is relatively slow, it will affect the subsequent engine start sequence, so a forced pull-up protection is set. When the drone's pull-up control process drops to 800m, and the flight control determines that the drone's attitude has not reached stability, it starts to force pull up, the engine is started, and it switches to the pitch channel control law under normal flight status, and the target pitch angle is 0°.

[0099] (3) Posture protection

[0100] Under normal flight conditions, the sub-machine will not have extreme attitude conditions. Therefore, when the sub-machine's pitch is greater than 70° and its roll is greater than 90°, and it does not correct within 4 seconds, the drone's attitude protection will be triggered. The flight control assumes that the drone is out of control and will issue a parachute opening command. During the drone's airborne launch phase, especially when the wings have not yet unfolded, it is normal for the drone to have large attitudes in pitch and roll for a long time. At this time, there is no need to trigger attitude protection. Instead, it is necessary to wait for the drone's wings to unfold and then slowly adjust the drone's attitude. Therefore, the drone's attitude protection logic during the airdrop phase is canceled. When the drone's airdrop process is successfully completed, that is, the engine is ignited successfully, the attitude protection logic is restored to normal flight conditions. (4) Altitude protection

[0101] Similar to the normal flight state, in the launch control method of the present invention, there is also a corresponding altitude protection to prevent a certain process error in the air-based launch, which may cause the UAV to crash at high speed. When the UAV altitude is lower than 100m, the altitude protection is triggered and the UAV opens its parachute to land.

[0102] In addition to the aforementioned launch control method process design, it is necessary to design the time intervals between each process, which is also called the air-based launch timing logic design. A suitable air-based launch timing logic can make the control process of the folding-wing UAV air-based launch more reasonable, more stable and safer, and can also reduce the risk of collision between the sub-machine and the mother machine, and reduce the large changes in the sub-machine's posture during the air-based launch process, thereby ensuring the success of the air-based launch mission. Therefore, the timing logic design in the present invention is as follows: Figure 3 As shown, the details are as follows:

[0103] Sequence 1: When detecting the separation signal, the ADC detects that the voltage changes to 0V (from presence to absence), and continuously detects the separation signal for 200ms to prevent misjudgment caused by voltage instability. The separation signal is continuously detected for 200ms, and the current time of separation detection is recorded as T0. At this time, the control is started, and the attitude of the aircraft in the folded state is adjusted through the tail rudder.

[0104] Sequence 2: unfold the wings. The moment T1 is 300ms after the detachment is detected. At this time, the flight control sends a command to the wing lock servo. The servo turns on and the wings start to rotate and unfold. T1 = T0 + 300ms.

[0105] Timing three: Lock the wings. 1300ms after the servo is turned on, it is time T2. At this moment, the wings are fully unfolded, T2=T1+1300ms. After the wings are fully unfolded, it takes 500ms to reach time T3', T3'=T2+500ms. The flight control gives the wing lock servo command, and the servo locks the wings.

[0106] Sequence 4: After the wings are fully deployed, the aircraft enters the unpowered gliding stage. After Nms, the attitude is considered stable, N = 5s ~ 20s; at this time, if the altitude is lower than the minimum parachute opening altitude, the parachute will be opened for landing. Sequence 5: At T3, the flight control gives the engine start command, T3 = T2 + Nms. After 3.3s, it is determined whether the engine has been started, that is, the speed is greater than 2000rpm for 3 seconds to prevent the wind from blowing the blades to rotate at high speed and causing misjudgment. The start completion time is recorded as T4; if it is detected that it has not started, it will restart after an interval of 2s; if the start fails 3 times and the altitude is greater than the minimum parachute opening altitude, it will continue to glide without power. If the altitude is lower than the minimum parachute opening altitude, the parachute will be opened for landing.

[0107] Sequence 6: When the engine is started, the aircraft enters the mission phase after the attitude stabilizes. If the engine is started successfully once, T4 = T3 + 3300ms, otherwise T4 is calculated based on the actual number of ignitions and time.

Claims

1. A method for launching an air-based mounted folding-wing UAV, characterized in that: The specific steps are: Step 1: The mother machine continuously supplies a voltage signal to the daughter machine as a signal voltage for airborne transmission; Step 2: The ground terminal confirms that the conditions for delivery are met and sends a delivery signal to the host machine, which enters the delivery state; Step 3: The flight control of the slave aircraft continuously monitors the voltage signal sent by the master aircraft in step 1; Step 4: The operator of the main machine cuts off the voltage signal, the locking device of the main machine is unlocked, the hook is opened, and the sub-machine is launched; Step 5: The slave flight control ADC detects the voltage signal. If the monitored voltage signal is 0 for a certain period of time, it means that it has been separated from the mother aircraft. The current time is recorded as T0 and the process goes to step 6. Step 6: The control surface of the tail wing of the sub-aircraft begins to be controlled, and the roll attitude of the aircraft in the folded state is adjusted by deflecting the control surface of the tail wing to suppress the lateral roll of the folded body; Step 7: After a period of time from time T0, time T1 comes. At time T1, the flight control sends a command to the wing lock servo, and the wing lock servo opens, controlling the wings to start rotating and unfolding. Step 8: After the wing lock servo is turned on, a period of time passes, which is called time T2. At this time, the wing is fully deployed, and the aileron intervenes to control the attitude of the sub-machine; after the wing is fully deployed, a period of time passes, which is called time T3'. At this time, the flight control sends a command to the wing lock servo, and the wing lock servo locks the wing; Step 9. After the wings are fully deployed, the sub-machine enters the unpowered gliding stage. At this time, the sub-machine dives at high speed and is pulled up and controlled by unpowered dive. After a period of time, the attitude is stable, and the attitude stability time is T3; if the height of the sub-machine is lower than the minimum parachute opening height, the parachute is opened and landed; if the height of the sub-machine is not lower than the minimum parachute opening height after the attitude is stable, step 10 is performed; Step 10: At T3, the flight control sends an engine start command to determine whether the engine has started. The engine start completion time is recorded as T4. If it is detected that the engine has not started, it will restart after an interval of 2 seconds. If the engine fails to start three times and the height of the sub-machine is lower than the minimum parachute opening height, the parachute will be opened for landing. If the height is greater than the minimum parachute opening height, the unpowered glide will continue. During the glide, the engine will be started by the ground station. If the start fails and the height of the sub-machine is lower than the minimum parachute opening height, the parachute will be opened for landing. Step 11: After the engine is started, exit the air-based launch process and the aircraft begins to enter the mission phase; Step 12: Use the traditional control laws in the air-based launch flight control module to carry out normal route missions until parachute recovery.

2. A method for launching an airborne folding-wing UAV as claimed in claim 1, characterized in that: In step six, the folded tail attitude control method is used, and the folded tail participates in the attitude control, and a 5° V-tail rudder stroke is allocated to control the pitch, and the control logic is the normal control logic; the 10° V-tail rudder stroke controls the roll, and the inner loop PID control is adopted, and the target control amount is the target roll angle Φ of the UAV a and the current roll angle of the drone Φ c The difference between the two is due to the target roll angle Φ of the drone at this stage. a It is always 0°, so the target control amount is also the UAV roll angle Φ c , perform PID link operation on the control quantity, and finally obtain the V tail differential steering quantity δ r1 ; The control law is: in, is the gain link control parameter, is the integral link control parameter, is the differential link gain.

3. A method for launching an air-based mounted folding-wing UAV as claimed in claim 1, characterized in that: In step nine, the pitch channel control method used in the power-free dive pull-up control is the pitch-airspeed closed-loop control. The various physical quantities and control parameters in the power-free dive pull-up control stage are: The pull-up phase indicator temp: temp shows 2 for pull-up preparation; shows 1 for pull-up in progress; shows 0 for pull-up completion; Pitch control airspeed proportional coefficient The default value is 2. Pitch control airspeed integral coefficient Default 0.1; The initial value of the UAV speed V0 measured at the beginning of the pull-up control; The speed V of the drone at the moment measured during the pull-up phase; Given the final target speed value V c : Cruising speed 50m / s; Given the initial speed offset ΔV; Exponential transition time constant T: default is 2s; Target speed V in the pull-up control phase tar : A function that changes exponentially with time T, with the initial time being V0+ΔV and the final time being V c ; The PI link is used to control the airspeed stability of the UAV. The control law is as follows: Get the elevator amount δ of the UAV in the pull-up control phase e_pull , used to control speed stability and pitch angle stability.

4. A method for launching an air-based mounted folding-wing UAV as claimed in claim 1, characterized in that: In step 9, the attitude stability judgment logic is: the current sub-aircraft pitch is within ±12 degrees, the roll angle is within ±10 degrees, and the current sub-aircraft airspeed is within the set airspeed value ±3.

5. The method for launching an air-based mounted folding-wing UAV as claimed in claim 1, characterized in that: The protection logic is designed during the drop and pull-up phases of the submachine to ensure the safety of air-based launch, including: (1) Engine start failure protection When the engine fails to ignite three times, the engine start failure protection logic is entered; at this time, the UAV will no longer start the engine and start to glide without power. The target waypoint of the glide is the home point. At this time, the home point is located at the initial point of the start of the casting, but the height is 150m. After reaching the home point, it starts to circle around the home point and waits for the next instruction from the ground station; during the entire protection period, the ground station is used to issue manual ignition instructions, or switch to semi-autonomous mode and use the remote control to manually control the UAV; if the engine is still not successfully started, during the circling and descending process, if it is below the height protection line, the height protection is triggered and the UAV opens the parachute to land. (2) Forced pull up When the altitude of the UAV during the pull-up control process reaches 800m, and the flight control determines that the UAV attitude has not yet reached stability, it starts to force the pull-up, the engine starts, and switches to the pitch channel control law under the normal flight state, with a target pitch angle of 0°. (3) Posture protection In the normal flight state of the sub-machine, if the sub-machine pitch is greater than 70° and roll is greater than 90°, and it is not corrected within 4 seconds, the attitude protection of the drone will be triggered. The flight control assumes that the drone is out of control at this time and will issue a parachute opening command; (4) High protection When the drone's altitude is lower than 100m, the altitude protection is triggered and the drone opens its parachute to land.

6. The method for launching an air-based mounted folding-wing UAV as claimed in claim 1, characterized in that: The sequential logic is: Timing 1: When detecting the separation signal, the ADC detects that the voltage has changed to 0V, and continuously detects the separation signal for 200ms to prevent misjudgment caused by voltage instability. The separation signal is continuously detected for 200ms, and the current time of separation detection is recorded as T0. At this time, the control is started, and the attitude of the aircraft in the folded state is adjusted through the tail rudder; Sequence 2: Wing unfolding. 300ms after the detachment is detected, which is T1. At this time, the flight control sends a command to the wing lock servo. The servo turns on and the wing starts to rotate and unfold. T1 = T0 + 300ms. Timing three: Lock the wings. After 1300ms from the servo opening, it is T2, at which the wings are fully deployed. T2 = T1 + 1300ms. After the wings are fully deployed, it takes 500ms to reach T3'. T3' = T2 + 500ms. The flight control sends a command to the servo to lock the wings, and the servo locks the wings. Sequence 4: After the wings are fully deployed, the aircraft enters the unpowered gliding stage. After Nms, the attitude is considered stable, N = 5s ~ 20s; at this time, if the altitude is lower than the minimum parachute opening altitude, the parachute will be opened for landing; Sequence 5: At T3, the flight control gives the engine start command, T3 = T2 + Nms; 3.3s later, it is determined whether the engine has started, that is, the speed is greater than 2000rpm for 3 seconds to prevent the wind from blowing the blades to rotate at high speed and causing misjudgment. The start completion time is recorded as T4; if it is detected that it has not started, it will restart after an interval of 2s; Sequence 6: When the engine is started, the aircraft enters the mission phase after the attitude stabilizes. If the engine is started successfully once, T4 = T3 + 3300ms, otherwise T4 is calculated based on the actual number of ignitions and time.

7. A control system for launching an airborne folding-wing UAV, characterized in that: It includes a folding wing V-tail layout UAV, a mounting mother machine, a flight control and navigation module, a ground station module, an air-based launch flight control module, and a hook and shackle; The belly of the mounting mother aircraft is installed with a hook, and the upper part of the fuselage of the child aircraft is installed with two longitudinally arranged hook rings. When on the ground, the hook is connected with the hook ring, and the mother and child aircraft are locked; when arriving at the air-based launch site, the mother aircraft sends a throwing command to the flight control of the child aircraft, and at the same time the hook on the belly of the mother aircraft is released, and the child aircraft is launched, performing a quasi-horizontal throwing movement; the flight control and navigation module is installed on the child aircraft, which is used for communication between the child aircraft and the mother aircraft and between the child aircraft and the ground station; the child aircraft is equipped with an air-based launch flight control module to ensure the successful air-based launch of the child aircraft and stable and normal flight; the ground station module is responsible for communication with the flight control, sending command signals, and observing the aircraft status; the air-based launch flight control module includes a launch control part of the air-based launch UAV and a launch timing logic part of the air-based launch UAV, a launch process control law part of the air-based launch UAV, a traditional control law part, and a protection logic part.

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