Foldable single-rotor slow-descent unpowered aircraft and control method thereof

Abstract

The invention discloses a foldable single-rotor slow-descent unpowered aircraft and a control method thereof, and belongs to the technical field of air-drop rescue and aviation. The aircraft mainly comprises a central main shaft, a foldable rotor wing mechanism, a gravity center adjusting mechanism and a control system. The foldable rotor wing mechanism is folded and stored before being released and is automatically unfolded after being released; the gravity center adjusting mechanism changes the overall gravity center of the aircraft by moving the position of the balancing weight, and therefore in the unpowered free falling process, the falling posture, the rotating speed and the falling speed of the aircraft are controlled through the coupling effect of aerodynamic lift force, aerodynamic resistance and gravity. The aircraft is simple in structure, low in cost, convenient to store and transport, capable of achieving stable spinning slow descent and accurate attitude control under the unpowered condition, and particularly suitable for scenes such as material air-drop, data collection, emergency rescue and low-altitude Internet of Things.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aviation technology and unmanned aerial vehicles, and particularly relates to a foldable aircraft capable of achieving slow descent by aerodynamic spinning without power and realizing accurate landing point control and a control method thereof. BACKGROUND

[0002] In the fields of material air drop, battlefield supply, disaster reconnaissance, data collection, low-altitude Internet of Things, etc., it is necessary to deliver the load from an aerial platform to a ground target point safely and accurately. The falling trajectory of the traditional parachute system is easily affected by wind disturbance, the landing point accuracy is poor, and the horizontal maneuvering capability is not available. Some powered unmanned aerial vehicles or guided ammunition have high accuracy, but are high in cost, complex in structure, limited in endurance time, and not applicable in some electromagnetic silent environments.

[0003] Unpowered spinning aircraft (such as the principle of "maple seed") provide a low-cost and high-reliability solution. They rely on airflow to drive the rotor to spin to generate lift and slow down the descent speed. However, most of the existing such devices can only achieve simple slow descent and cannot effectively control the falling trajectory, or their control mechanisms are complex and difficult to realize miniaturization and low cost.

[0004] Therefore, there is an urgent need for an unpowered flying device that has the advantages of convenient storage and transportation, slow descent stability, and controllable landing point. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art and provide an unpowered slow descent aircraft with simple structure, foldability, and accurate attitude control capability and a control method thereof.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: A foldable single-rotor slow descent unpowered aircraft, comprising a central main shaft, a foldable rotor mechanism, a gravity center adjusting mechanism, and a control system.

[0007] The foldable rotor mechanism is installed at the top of the central main shaft and is composed of at least two rotor arms and blades. The rotor arms are connected to the main shaft through folding mechanisms such as torsion spring hinges. In the storage state, the rotor arms are folded close to the main shaft, greatly reducing the volume; after being released, they are quickly unfolded under the action of torsion springs or driving mechanisms and enter the working state.

[0008] The gravity center adjusting mechanism is the core of the present application for control. It includes a counterweight block movable along a guide rail and a motor driving the same. The guide rail can be arranged along the axial direction of the main shaft (controlling the pitch), or can be designed to move in the radial plane (controlling the roll and yaw, and then controlling the horizontal direction).

[0009] The control system is integrated with a microprocessor, power supply and sensors (such as IMU, GPS). It receives sensor data, calculates the deviation between the current flight state and the target state, and then issues instructions to the gravity center adjustment mechanism to move the counterweight, thereby changing the center of gravity of the entire system. When the center of gravity deviates from the aerodynamic center (pressure center), a control moment is generated, causing the aircraft to pitch or tilt, thereby changing the direction of the aerodynamic force and achieving trajectory control.

[0010] The control method of the present application comprises: - Release and deployment: after being thrown from the plane or drone, the rotors automatically pop open.

[0011] - Stable spinning and data sensing: the aircraft falls under the action of gravity, and the airflow drives the rotors to spin to generate lift, entering the stable spinning and slow descent phase. Sensors continuously collect data.

[0012] - Active attitude control: the control system calculates the deviation from the target landing point based on GPS coordinates and inertial data. By moving the counterweight, the pitch and tilt angles of the aircraft are finely adjusted. For example, when flying forward is needed, the counterweight is moved forward, causing the nose to pitch down, and the lift vector generates a forward component, pushing the aircraft forward.

[0013] - Landing preparation: when approaching the ground, the attitude can be adjusted to vertical and land gently at the lowest speed.

[0014] The present application has the following advantages: 1. Completely unpowered: relying only on aerodynamic principles, it has good concealment and unlimited endurance.

[0015] 2. High precision control: attitude control is achieved by moving internal counterweights, breaking through the limitations of traditional unpowered aircraft.

[0016] 3. Easy to store and transport: foldable design makes it small in volume before launch, especially suitable for carrying large quantities inside limited space carriers.

[0017] 4. Low cost and high reliability: simple mechanical structure, no complex propulsion system, low cost and low failure rate. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a schematic diagram of the three-dimensional structure of the aircraft in the deployed state.

[0019] Figure 2 is a flowchart of the control method of the present application. DETAILED DESCRIPTION

[0020] The present application will be described in detail below in conjunction with the drawings and specific examples.

[0021] As Figure 1 shown, the foldable single-rotor slow-falling unpowered aircraft of the present application includes a central main shaft. The upper end of the main shaft is connected with a wing arm through a torsion spring hinge, and the end of each rotor arm is fixed with a high-lift-drag ratio blade. In the non-working state, the rotor arm can be retracted and folded. The middle part of the main shaft is provided with a gravity center adjusting mechanism, and the lower part is a load cabin for placing materials.

[0022] As Figure 1 shown, one specific embodiment of the gravity center adjusting mechanism includes a guide rail fixed along the axis of the main shaft, an axial counterweight block that can slide along the guide rail, and a micro stepping motor driven by a lead screw. When the motor rotates, it drives the lead screw nut pair, thereby driving the counterweight block to move up and down accurately.

[0023] The control system includes a main control MCU 71 (micro control unit) which is electrically connected with the sensor module (including IMU, GPS), the driving circuit (used for controlling the gravity center adjusting motor) and the unfolding mechanism driver respectively. The power supply supplies power to the whole system.

[0024] The working process of the present application is as Figure 2 shown: - S1: Deployment: the aircraft is thrown out of the carrier.

[0025] - S2: Rotor unfolding: the main control MCU 71 detects the free-fall state and instructs the unfolding mechanism driver to unlock, and the rotor arm 2 rapidly unfolds to the horizontal position under the action of the torsion spring.

[0026] - S3: Stable spinning slow-falling: air flow acts on the blades, driving the whole aircraft to rotate around the main shaft and generating upward lift to offset part of the gravity, entering the stable slow-falling stage.

[0027] - S4: Perception and decision: GPS and IMU continuously provide position, speed, attitude angle data. MCU 71 compares these data with the preset target landing point and calculates the required counterweight block moving direction and distance through the built-in control algorithm (such as PID controller).

[0028] - S5: Control execution: MCU 71 controls the stepping motor through the driving circuit to move the counterweight block to the specified position. The gravity center offset causes the aircraft attitude to change, thereby realizing turning, accelerating or decelerating.

[0029] - S6: Loop judgment: constantly repeat S4 and S5 until the height of the aircraft is lower than the safety threshold.

[0030] - S7: Landing: adjust the aircraft to a vertical attitude and land smoothly.

[0031] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements within the technical scope disclosed by the present application can be easily conceived by those skilled in the art, and shall be covered within the protection scope of the present application.

Claims

1. A foldable single rotor, parafoil, unpowered aircraft, characterized by: The aircraft comprises a central shaft, a foldable rotor mechanism, a gravity center adjusting mechanism and a control system. The foldable rotor mechanism is installed on the upper part of the central shaft and comprises a rotor arm and a propeller blade arranged at the end of the rotor arm. The rotor arm is connected with the central shaft through a folding mechanism, so that the rotor arm can be switched between a storage state and a deployment state. The gravity center adjusting mechanism is arranged on the central shaft and is used to change the overall gravity center position of the aircraft. The control system is electrically connected with the foldable rotor mechanism and the gravity center adjusting mechanism, and is used to control the deployment and folding of the rotor arm and the adjustment of the gravity center position by the gravity center adjusting mechanism.

2. A foldable single rotor, slow motion, non-powered flying vehicle according to claim 1, characterized in that: The folding mechanism is one of a torsion spring hinge, a shape memory alloy actuator or a hinge mechanism driven by a motor.

3. A foldable single rotor, slow motion, non-powered flying vehicle according to claim 1 or 2, characterized in that: The gravity center adjusting mechanism comprises a guide rail, a counterweight and a driving unit. The guide rail is arranged along the axial direction or the radial direction of the central shaft. The counterweight is slidably arranged on the guide rail. The driving unit is connected with the counterweight and is used to drive the counterweight to move along the guide rail.

4. A foldable single rotor, slow motion, non-powered flying vehicle according to claim 3, characterized in that: The driving unit is a micro stepping motor, a servo motor or a linear motor.

5. The foldable single rotor, slow motion, non-powered aerial vehicle of claim 1 wherein: A sensor module is further arranged on the central shaft. The sensor module comprises one or more of a GPS module, an inertial measurement unit, a barometer and a gyroscope. The sensor module is in communication connection with the control system.

6. The foldable single rotor, slow motion, non-powered aerial vehicle of claim 1 wherein: The propeller blade profile is a thin film profile, a symmetrical profile or a concave-convex profile with high lift-drag ratio.

7. The foldable single rotor, slow motion, non-powered aerial vehicle of claim 1, wherein: The lower part of the central shaft is provided with a load cabin for accommodating the materials or equipment to be dropped.

8. A control method for the foldable single rotor, slow motion, non-powered flying vehicle of any of claims 1-7, characterized in that The method comprises the following steps: A release and deployment step: after the aircraft is released from the carrier, the control system sends a command to switch the foldable rotor mechanism from the storage state to the deployment state. A data acquisition step: the attitude, position and height information of the aircraft is acquired in real time by the sensor module. An attitude control step: the control system calculates the required gravity center offset according to the preset target landing point and the real-time acquired data, drives the gravity center adjusting mechanism to move the counterweight to the target position, changes the relative position of the aerodynamic center and the gravity center to generate a control moment, and thus adjusts the falling trajectory and attitude of the aircraft.

9. The control method according to claim 8, characterized in that: In the attitude control step, the trajectory correction of the aircraft in the horizontal direction is realized by controlling the movement of the counterweight in the radial plane. The rotation rate and the falling speed are adjusted by controlling the axial movement of the counterweight to change the pitch angle of the aircraft.

10. The control method according to claim 8, characterized in that: A pre-landing preparation step is further included: when the aircraft descends to a predetermined height, the control system can instruct the gravity center adjusting mechanism to move the counterweight to the center position, so that the aircraft lands stably in a vertical attitude, or instructs the rotor mechanism to be partially folded to reduce the landing impact.

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