Control method for gliding parachute-opening landing of unmanned aerial vehicle

Abstract

The invention discloses a control method for gliding parachute-opening landing of an unmanned aerial vehicle, belongs to the technical field of safe landing of the unmanned aerial vehicle, and utilizes the unmanned aerial vehicle to enter gliding and adjust various states and parameters of the unmanned aerial vehicle to enable the unmanned aerial vehicle to meet conditions of safe parachute landing. The method comprises the following steps that an aircraft follows a route in an approaching state, and an automatic accelerator is controlled by speed; in the lifting rate zeroing stage, transverse guidance is closed, longitudinal guidance is controlled by the lifting rate, and an automatic accelerator is closed; in the gliding stage, longitudinal guidance is controlled by speed, and airspeed is equal to recovery speed; in the recovery stage, the longitudinal guidance is closed, the pitch angle is equal to the sum of the increment of the climbing angle and the increment of the attack angle of the parachute opening action, and the recovery system is started and parachute opening is performed until the aircraft lands safely to complete landing.

Description

Technical Field

[0001] This invention belongs to the field of unmanned aerial vehicle (UAV) safe landing technology, specifically relating to a control method for UAV gliding and parachute landing. Background Technology

[0002] With the rapid development of drone technology, drones have been applied in various fields and are playing an important role. However, drone accidents are also occurring frequently, and people are paying increasing attention to drone flight safety. Drone parachute technology is one way to ensure drone flight safety. During flight, a drone may need to make an emergency landing due to malfunction or other reasons. In this case, a specific triggering mechanism will deploy a parachute to slow down the drone's descent and ensure a safe landing. This is the drone parachute system.

[0003] The development history of drone parachute technology is mainly as follows:

[0004] Early Exploration (Late 20th Century): Initially, drone parachute systems were primarily used in the military as emergency escape devices to improve flight safety. Civilian Expansion (Early 21st Century): With the rise of the civilian drone market, parachute system design began to focus on lightweighting and portability to meet the diverse needs of logistics, agriculture, film and television production, and other fields.

[0005] Technological advancements (2010s): The application of new materials and technologies significantly improved the performance of parachute systems, making them more reliable and efficient;

[0006] Intelligent Development (2020s): Modern UAV parachute systems are gradually developing towards intelligence and high reliability, possessing functions such as automatic parachute deployment and automatic recovery, and can optimize landing trajectories through intelligent algorithms; Technological Advancements: Material and Structural Optimization: High-strength, corrosion-resistant materials are used to manufacture parachute wings and lines, improving the system's durability and reliability; Intelligent Control Technology: Deep reinforcement learning (DRL) and neural network control algorithms are introduced to achieve more precise trajectory planning and attitude control. Multibody Dynamics Simulation: By establishing multibody dynamics models, the attitude control and line tension during parachute descent are analyzed to optimize parachute design and performance. Remotely Controlled Parachute: Liexu Intelligent's remotely controlled parachute system can activate the parachute when necessary via remote control commands, adjusting the landing trajectory in real time to ensure safe landing of the UAV.

[0007] Traditional parachute systems typically require drones to be at specific altitudes, speeds, and attitudes to deploy properly and land safely. However, in some situations, drones may not meet the requirements for direct parachute deployment due to flight conditions such as excessive speed, low altitude, or abnormal attitude. Forcing the parachute to deploy under these circumstances may result in the parachute failing to deploy properly, or even cause greater harm to the drone and personnel on the ground. Summary of the Invention

[0008] This invention provides a control method for gliding and parachute landing of a drone, which enables the drone to enter a gliding state when it does not meet the conditions for direct parachute landing, and adjusts various states and parameters of the aircraft to meet the conditions for safe parachute landing.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A control method for gliding and parachute-deployed landing of a drone includes the following steps: During the approach phase, the drone follows the flight path, and the automatic throttle is controlled by speed. When entering the zero-rate-of-climb phase, lateral guidance is turned off, longitudinal guidance uses the rate of climb to control the pitch angle, and auto throttle is turned off. The drone's flight status is monitored in real time to determine whether the conditions for direct parachute landing are met. If not, the drone is switched to gliding mode, and its flight attitude and speed are adjusted to guide it to glide to suitable parachute landing conditions. During the gliding phase, longitudinal guidance is achieved by controlling the pitch angle with airspeed. Once the parachute landing conditions are met, the aircraft enters the recovery phase. Longitudinal guidance is deactivated, the aircraft's pitch angle is the sum of the climb angle and the angle of attack increment of the parachute deployment maneuver, the recovery system is activated, and the parachute deploys for landing.

[0011] Beneficial Effects: This invention provides a control method for gliding and parachute-deployed landing of unmanned aerial vehicles (UAVs). By monitoring the UAV's flight status (such as altitude, speed, and attitude) in real time, the system can automatically determine whether the conditions for direct parachute landing are met. If the conditions are not met, the system will automatically switch to gliding mode, adjust the UAV's flight attitude and speed, and guide it to glide to a safe altitude and speed range suitable for parachute landing. The entire process is fully automated, requiring no manual intervention, greatly improving the safety and reliability of emergency landings. Moreover, this invention effectively avoids problems such as parachute malfunction due to forced deployment, reduces the impact force on the UAV upon landing, and protects the safety of the UAV and ground personnel and facilities. The intelligent design of this invention is applicable to various types of UAVs, has broad applicability and promotional value, and provides strong protection for the safe operation of UAVs. Attached Figure Description

[0012] Figure 1 This is a control flowchart for the gliding and parachute landing of a drone in an embodiment of the present invention;

[0013] Figure 2 This is the acceleration / deceleration rate control law structure in the embodiments of the present invention;

[0014] Figure 3 This is a diagram of the track angle control structure in an embodiment of the present invention;

[0015] Figure 4 This is a structural diagram of the speed control loop in an embodiment of the present invention;

[0016] Figure 5 This is a landing code diagram used in an embodiment of the present invention;

[0017] Figure 6 This is a diagram showing the relative altitude parameters of the flight path during the landing phase of the experiment in this invention;

[0018] Figure 7 This is a diagram showing the longitudinal guidance parameters during the landing phase of the experiment in this invention.

[0019] Figure 8 This is a diagram showing the state airspeed and indicated airspeed parameters during the landing phase of the experiment in this invention;

[0020] Figure 9 This is a diagram showing the ascent and descent rates and ascent and descent rate command parameters during the landing phase of the experiment in this invention;

[0021] Figure 10 This is a diagram showing the parachute deployment parameters during the landing phase of the experiment in this invention. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments:

[0023] like Figure 1 As shown, the parachute deployment of a drone during gliding mainly consists of the following processes:

[0024] The first step is the drone's approach phase, preparing for landing. At this time, the aircraft follows the flight path, keeping its airspeed at the minimum indicated speed.

[0025] The second step is to enter the zero-rate-of-climb phase when the aircraft's position is less than the distance to the last waypoint, turn off the lateral guidance, use the rate of climb to control the pitch angle, and turn off the autothrottle.

[0026] The aforementioned climb rate control utilizes the climb rate to control the pitch angle, thereby controlling the climb rate. Convert to track tilt command Then, after conversion, the pitch angle command is obtained. ,like Figure 2 As shown, the acceleration and deceleration speeds can be determined geometrically. and track inclination The transformation relationships are as follows: , in This represents the ground speed of the drone.

[0027] like Figure 3 As shown, the track angle command Convert to pitch command The process is as follows: The relationship between pitch angle, angle of attack, and track inclination angle is as follows: , in, The pitch angle, For the angle of attack, The inclination angle of the flight path.

[0028] Considering the following relationship between the rate of change of the track inclination and the angle of attack: , in, The rate of change of the track inclination. air density, This is the actual airspeed of the drone. This is the reference area for the wing. This is the derivative of the lift coefficient with respect to the angle of attack. It's about the quality of the drone. The parameters related to the derivative of the track inclination angle with respect to the angle of attack are:

[0029] Combining the above two equations, we can obtain the transfer function from pitch angle to track inclination angle as follows: , in, For the Laplace operator.

[0030] The pitch angle controller can quickly track commands and has good robustness. The pitch angle command to pitch angle transition can be considered a first-order dynamic process, i.e.: , in, Given the control bandwidth of the pitch angle loop, and combining the above two equations, the transfer function from pitch angle command to track tilt angle can be described as: .

[0031] Design control laws to address negative points Meanwhile, an integrator is introduced, and the control law is as follows: .

[0032] The closed-loop transfer function and its corresponding characteristic equation are as follows: , .

[0033] definition and Here, represents the bandwidth and damping ratio of the track angle control loop, respectively, and the corresponding expressions are: ,

[0034] By setting the appropriate damping ratio, the bandwidth of the pitch angle loop can be controlled. Calculate the tracking gain of the track angle. for:

[0035] .

[0036] The third step involves entering the gliding phase when the indicated airspeed is less than or equal to the recovery airspeed. Longitudinal guidance is then achieved by controlling the pitch angle with airspeed, continuing this process until the drone glides to a safe altitude and speed range suitable for parachute landing. The pitch angle is then controlled by airspeed. Figure 4 As shown, the transformation relationship is as follows: , in It is the acceleration due to gravity. For pitch gain, For pitch angle command, For airspeed command, The actual airspeed is then set to the recovery speed.

[0037] Fourth, when the engine speed stops and the relative altitude is greater than the parachute deployment decision altitude, the aircraft enters the maximum pitch phase. The longitudinal guidance is turned off, and the pitch angle command is set to the sum of the climb angle and the increment of the parachute deployment angle of attack. The command code is tht_c=gamma_temp+d_tht_c. The purpose is to adjust the aircraft attitude and ensure that the parachute can deploy smoothly and stably through a specific angle of attack. After a 1-second delay, there is a buffer period before the parachute deployment action is executed, allowing the system to complete the preparation work such as mode switching and parameter adjustment in an orderly manner, making the execution of the parachute deployment action more stable and reliable. The recovery system is activated, the parachute is deployed, and during the landing phase, the control law is turned off until the aircraft touches the ground and the landing is completed.

[0038] Simulation verification

[0039] This simulation recorded the flight data of the UAV from approach to landing. Figure 6-10 The data graphs of the experimental process are displayed. Figure 6 This shows the change in the aircraft's relative altitude over time during the test. Figure 7 It shows the change of the longitudinal guidance mode over time. Figure 8 It displays the changes in airspeed and air velocity over time. Figure 9 The display shows the lifting / climbing rate command and how the lifting / climbing rate changes over time. Figure 10 The graph shows whether the parachute has deployed. The data in the graph demonstrates that the aircraft performed attitude control during the test flight, following the procedure in the parachute deployment logic diagram to ensure that the aircraft reached the appropriate conditions for parachute deployment.

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A control method for gliding and parachute-deployed landing of an unmanned aerial vehicle (UAV), characterized in that, Includes the following steps: The drone's flight status is monitored in real time to determine whether the conditions for direct parachute landing are met. If not, the drone is switched to gliding mode, and its flight attitude and speed are adjusted to guide it to glide to suitable parachute landing conditions. During the gliding phase, longitudinal guidance is achieved by controlling the pitch angle with airspeed. Once the parachute landing conditions are met, the aircraft enters the recovery phase. Longitudinal guidance is deactivated, the aircraft's pitch angle is the sum of the climb angle and the angle of attack increment of the parachute deployment maneuver, the recovery system is activated, and the parachute deploys for landing.

2. The control method for gliding and parachute landing of an unmanned aerial vehicle according to claim 1, characterized in that, Before determining whether the UAV meets the conditions for direct parachute landing, when the aircraft's position is less than the distance to the last waypoint, and it enters the zero-rate-of-climb phase, lateral guidance is turned off, and longitudinal guidance is used to control the pitch angle by the rate of climb.

3. The control method for gliding and parachute landing of an unmanned aerial vehicle according to claim 2, characterized in that, The climb rate control uses the climb rate to control the pitch angle, converts the climb rate into a track tilt command, and then converts it into a pitch angle command.

4. The control method for gliding and parachute landing of an unmanned aerial vehicle according to claim 3, characterized in that, The transfer function from pitch angle command to track tilt angle is: ， In the formula, For pitch angle command, For the inclination angle of the flight path, For parameters related to the derivative of the track inclination angle with respect to the angle of attack, The control bandwidth of the pitch angle loop, For the Laplace operator.

5. The control method for gliding and parachute landing of an unmanned aerial vehicle according to claim 4, characterized in that, Design control laws to address negative points Meanwhile, an integrator is introduced, and the control law is as follows: ， In the formula, For track angle tracking gain, This is the track angle command.

6. The control method for gliding and parachute landing of an unmanned aerial vehicle according to claim 5, characterized in that, Control bandwidth via pitch angle loop Calculate the tracking gain of the track angle. for: ， In the formula, This is the damping ratio of the track angle control loop.

7. The control method for gliding and parachute landing of an unmanned aerial vehicle according to claim 1 or 6, characterized in that, During the gliding phase, the relationship between airspeed and pitch angle is as follows: ， in It is the acceleration due to gravity. For pitch gain, For pitch angle command, For airspeed command, This is the actual airspeed.

8. The control method for gliding and parachute landing of an unmanned aerial vehicle according to claim 7, characterized in that, The airspeed is set to the recovery speed.

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