A UAV landing bracket, system and landing method

Abstract

The present invention specifically relates to a landing bracket, system and landing method for unmanned aerial vehicles, including a movable leg mechanism and a tensioning mechanism, wherein the movable leg mechanism is connected to the tensioning mechanism, the movable leg mechanism can be extended / retracted relative to the unmanned aerial vehicle, and the movable leg mechanism is a flexible structural member; the tensioning mechanism is used to tension the extended portion of the movable leg mechanism after the movable leg mechanism is extended from the unmanned aerial vehicle, and the extended portion is a rigid structure; when the unmanned aerial vehicle lands, the fuselage posture detection system detects the posture information of the unmanned aerial vehicle and gives feedback, and adjusts the height of the chain feet at different positions of the landing bracket in real time, compensates for the height difference of the landing position, maintains the fuselage level, and adjusts the fuselage height and tilt angle. The purpose is to enable the unmanned aerial vehicle to have the ability to take off and land on any ground through the bracket and system, thereby expanding the landing range of the unmanned aerial vehicle, and also avoiding the interference of the fuselage shaking and rotor wind force when the unmanned aerial vehicle performs microscopic operations.

Description

Technical Field

[0001] The present invention belongs to the technical field of precision operation of unmanned aerial vehicles, and in particular relates to a landing bracket, a system and a landing method for unmanned aerial vehicles. Background Art

[0002] Drones have a wide range of applications, especially in the field of aerial photography. They can carry different imaging equipment and perform imaging of different spectra. However, currently, drones can only take off and land in relatively flat areas, and microscopic operations on targets anywhere are of great significance, especially in the agricultural field. Microscopic observation of plant phenotypes is required in the fields of breeding new species and pesticide research and development. In some special scenarios (such as uneven areas such as hillsides), microscopic photography and microscopic sample collection of targets are also required.

[0003] The low precision of drones in microscopic operations is mainly caused by the vibration of the drone body when the motor rotates. For example, in the field of microscopic imaging, current microscopic imaging equipment (stereo microscopes and other microscopic imaging equipment) is very sensitive to vibration, so drones equipped with microscopic imaging equipment cannot obtain clear imaging targets. At the same time, the wind force caused by the rotation of the drone's rotor also causes certain interference to the drone's microscopic operations. In the field of microscopic sampling, the interference of wind force (especially the collection of plant samples) and the vibration of the fuselage make it impossible for the sampling facilities to accurately obtain the target.

[0004] Therefore, the best method for microscopic operations is to hover or stay at the location where the drone needs to be photographed, and then use support to reduce the vibration of the drone caused by the rotation of the motor, so that the drone can perform precise operations. However, due to the limitations of the landing gear, existing drones cannot hover or stay directly on roads of any shape, and cannot perform their operations. The terrain conditions restrict the take-off and landing of drones, which further restricts the drone's microscopic operations. Summary of the invention

[0005] In order to solve the above-mentioned problems, the present invention provides a UAV landing bracket, system and landing method. The bracket and system can enable the UAV to take off and land on any ground, thereby expanding the landing range of the UAV, and also avoiding the interference of the body shaking and rotor wind force when the UAV performs microscopic operations.

[0006] The technical solution adopted by the present invention is: a UAV landing bracket, including a movable leg mechanism and a tensioning mechanism, the movable leg mechanism and the tensioning mechanism are connected, the movable leg mechanism can be extended / retracted relative to the UAV, and the movable leg mechanism is a flexible structural member; the tensioning mechanism is used to tension the extended part of the movable leg mechanism after the movable leg mechanism is extended from the UAV, and the extended part is a rigid structure.

[0007] Preferably, the movable leg mechanism includes a curling portion and a supporting portion, the curling portion is flexibly wound inside the UAV; the supporting portion is connected to a tensioning mechanism, the supporting portion extends out of the UAV and is pulled and tensioned by the tensioning mechanism to form a rigid support, and the supporting portion provides supporting force for the UAV.

[0008] Preferably, the movable leg mechanism is a one-way bending chain, which is composed of a number of connecting blocks hinged in sequence, and the connecting blocks can slide relative to each other. The movable leg mechanism is driven to extend / retract to the drone through a rotating mechanism; a chain foot is provided at the end of the upper support part of the movable leg mechanism, and the chain foot is connected to the tensioning mechanism.

[0009] Preferably, the rotating mechanism includes a sprocket, which is connected to the first motor, and the sprocket is meshed with a one-way curved chain; the one-way curved chain extends outside the drone through a chain guide, and the chain guide is arranged inside the drone, and the length of the chain guide is equivalent to the length of the one-way curved chain portion tensioned by a tensioning mechanism inside the drone.

[0010] Preferably, the tensioning mechanism includes a wire wheel, on which a pull wire is provided, one end of the pull wire is fixedly connected to the wire wheel, and the other end of the pull wire passes through a chain guide and is connected to a chain foot; the wire wheel is connected to a second motor, and a wire pressing wheel is provided at an entrance end of the chain guide and close to one side of the wire wheel, the wire pressing wheel fits tightly with the pull wire, and the wire pressing wheel presses the pull wire in the same direction as the force supported by the support part.

[0011] A UAV landing system includes an actuator and a control mechanism;

[0012] The actuator is a lifting frame, a one-way bending chain is arranged inside the lifting frame, the one-way bending chain is composed of a plurality of connecting blocks hinged in sequence, two of the connecting blocks can slide relative to each other, and the one-way bending chain is driven to extend / retract to the UAV through a rotating mechanism; the one-way bending chain includes a curling part and a supporting part, the curling part is flexibly wound inside the UAV, a chain foot is arranged at the end of the upper supporting part, and the chain foot is connected to a tensioning mechanism; the supporting part extends out of the UAV and is pulled and tensioned by the tensioning mechanism to form a rigid support, and the supporting part provides support force for the UAV; the number of the actuators arranged is not less than the minimum points at which the UAV remains stable after landing;

[0013] The control mechanism includes an inclination measurement sensor, an angular velocity sensor, a pressure sensor, a distance sensor and a controller. The inclination measurement sensor and the distance sensor are arranged inside the drone, and the pressure sensor and the distance sensor are arranged on the chain foot; the inclination measurement sensor, the distance sensor, the pressure sensor, the distance sensor and the controller are connected, and the controller is connected to the rotor control motor and the actuator on the drone.

[0014] Preferably, the rotating mechanism includes a sprocket, which is connected to the first motor, and the sprocket is meshed with a one-way curved chain; the one-way curved chain extends outside the drone through a chain guide, and the chain guide is arranged inside the drone, and the length of the chain guide is equivalent to the length of the one-way curved chain portion tensioned by a tensioning mechanism inside the drone.

[0015] Preferably, the tensioning mechanism includes a wire wheel, on which a pull wire is provided, one end of the pull wire is fixedly connected to the wire wheel, and the other end of the pull wire passes through a chain guide and is connected to a chain foot; the wire wheel is connected to a second motor, and a wire pressing wheel is provided at an entrance end of the chain guide and close to one side of the wire wheel, the wire pressing wheel fits tightly with the pull wire, and the wire pressing wheel presses the pull wire in the same direction as the force supported by the support part.

[0016] A method for landing a drone comprises the following steps:

[0017] S1: Determine the landing position: The UAV evaluates the ground undulation data of the landing position during the landing process through the posture detection system in the fuselage, and evaluates the distance between the landing brackets on the fuselage of the UAV and the landing position. After determining the distance, the landing bracket is lowered according to the determined distance; the landing bracket is a lifting frame, and a one-way bending chain is arranged in the lifting frame. The one-way bending chain is composed of a plurality of connecting blocks hinged in sequence, and the two connecting blocks can slide relative to each other. The one-way bending chain is driven to extend / retract to the UAV through a rotating mechanism; the one-way bending chain includes a curling part and a supporting part, the curling part is flexibly wound in the UAV, and a chain foot is arranged at the end of the upper supporting part, and the chain foot is connected to a tensioning mechanism; the supporting part extends out of the UAV and is pulled and tensioned by the tensioning mechanism to form a rigid support, and the supporting part provides support force for the UAV;

[0018] S2: Lowering the supporting chain foot: The chain foot is lowered, and during the lowering process, the distance between the chain foot and the ground is continuously evaluated through the posture detection system in the fuselage. When the chain foot touches the ground, the final length of the chain foot is determined by the feedback of the pressure value in the posture detection system in the fuselage. The fuselage inclination angle and suspension height are detected by the fuselage posture detection system, and the rotor speed is adjusted in real time to adjust the suspension force, so as to maintain the relative stability of the rotor suspension force and the sum of the pressure on the chain foot. The rotor speed is gradually reduced to maintain the horizontal landing posture of the UAV.

[0019] S3: Fuselage posture adjustment: After the UAV lands smoothly, the posture detection system inside the fuselage evaluates the fuselage inclination data and feeds back to the controller inside the UAV. If the fuselage needs to remain level, the central processor controls the one-way bending chain in the landing bracket to extend / retract to eliminate the fuselage inclination; if the fuselage needs to have a certain inclination for operation, the landing brackets at different locations on the UAV are controlled to extend / retract according to the required inclination, so that the UAV is adjusted to the required inclination when operation is required.

[0020] Preferably, the posture detection system in the fuselage includes an inclination measurement sensor, an angular velocity sensor, a pressure sensor, a ranging sensor and a controller, the inclination sensor, infrared sensor and angular velocity sensor are arranged inside the drone, and the pressure sensor and ranging sensor are arranged on the chain foot; the inclination sensor, infrared sensor, angular velocity sensor, pressure sensor, ranging sensor and the controller are connected, and the controller is connected to the rotor control motor and actuator on the drone.

[0021] The present invention has the following beneficial effects:

[0022] 1. The landing bracket of the present invention adopts a one-way bending chain with a flexible structure, which can be curled and stored inside the drone or the shell of the landing bracket, so as to ensure that it can be extended and retracted to different lengths according to any terrain; the one-way bending chain of the present invention is tightened by a pull wire, and a rigid structure is formed after tightening, so as to support the drone. The one-way bending chain of the present invention can be converted between flexibility and rigidity as needed, so as to meet different usage requirements;

[0023] 2. The present invention determines whether the drone has landed successfully through double detection of the pressure sensor and the distance sensor at the chain foot. When the chain foot contacts the landing ground with complex terrain and the contact point supporting the chain foot avoids the detection range of the pressure sensor, the pressure sensor fails to detect the pressure value and needs to be verified by the distance sensor. The chain foot continues to be lowered. When the distance sensor of the chain foot detects that the distance between the chain foot and the landing ground no longer changes and the fuselage is tilted, it is determined that the drone chain foot has landed successfully. The successful landing of the drone is ensured by double detection.

[0024] 3. The landing bracket of the present invention is determined according to the minimum number of landing points at which the UAV can maintain stability. The extension length of each landing bracket can be adjusted separately, and each landing bracket can be independently controlled, so that the extension length can be determined according to different terrains, so that the UAV can land smoothly on various non-horizontal grounds, expanding the operating range of the UAV. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the floor stand of the present invention;

[0026] Figure 2 It is a schematic diagram of the external structure of the floor stand;

[0027] Figure 3 This is a schematic diagram of the structure of the drone. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0029] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0030] Embodiment 1

[0031] like Figure 1-3 As shown, a UAV landing bracket includes a movable leg mechanism and a tensioning mechanism, wherein the movable leg mechanism is connected to the tensioning mechanism, and the movable leg mechanism can be extended / retracted relative to the UAV, and forms a landing bracket after being extended, which can support the UAV to land smoothly on the ground, and the movable leg mechanism is a flexible structural member; the tensioning mechanism is used to tension the extended part of the movable leg mechanism after the movable leg mechanism is extended from the UAV, and the extended part is a rigid structure.

[0032] The movable leg mechanism includes a curling portion and a supporting portion. The curling portion is flexibly wound inside the drone. The curling portion is a flexible structure and can be coiled inside the drone, or a separate bracket shell is provided to arrange the movable leg mechanism therein; the supporting portion is connected to a tensioning mechanism, the supporting portion extends out of the drone and is pulled and tensioned by the tensioning mechanism to form a rigid support, and the supporting portion provides support force for the drone.

[0033] In the present invention, the movable leg mechanism is a one-way bending chain 2, which is composed of a number of connecting blocks hinged in sequence, one side of the connecting block is toothed, so that it can mesh with the sprocket 6, and the connecting blocks can slide relative to each other, that is, there is a space for relative movement between the connecting blocks, and the space can maintain the meshing with the sprocket 6. The movable leg mechanism is driven to extend / retract to the drone through a rotating mechanism; a chain foot 9 is provided at the end of the upper support part of the movable leg mechanism, and the area of ​​the chain foot 9 is an area that can support the smooth landing of the drone. The chain foot 9 is connected to the tensioning mechanism, and the tensioning mechanism is pulled to make the connecting blocks extending from the drone fit tightly one by one, thereby forming a rigid structure to provide supporting force.

[0034] The rotating mechanism includes a sprocket 6, which is connected to the first motor 14, and the sprocket 6 is meshed with the one-way bending chain 2; the one-way bending chain 2 extends outside the UAV through a chain guide 7, and the chain guide 7 is arranged inside the UAV, and the length of the chain guide 7 is equivalent to the length of the one-way bending chain 2 part tensioned by the tensioning mechanism inside the UAV. Figure 1 As shown, when vertical, there is bending space to the left, but no bending space to the right.

[0035] The tensioning mechanism includes a wire wheel 5, which is located on the non-bendable side of the one-way bending chain 2. A wire pull 4 is arranged on the wire wheel 5. One end of the wire pull 4 is fixedly connected to the wire wheel 5, and the other end of the wire pull 4 passes through the chain guide 7 and is connected to the chain foot 9; the wire wheel 5 is connected to the second motor 10, and a wire pressing wheel 3 is arranged at the entrance end of the chain guide 7 and close to the wire wheel 5. The wire pressing wheel is closely fitted with the wire pull 4, and the wire pressing wheel presses the wire pull 4 in the same direction as the force supported by the support part. When the one-way bending chain 2 cooperates with the sprocket 6, it is tangent to the edge line of the sprocket 6. One end of the one-way bending chain 2 is installed on the rotating shaft inside the shell to form a storage chain wheel 8, and one end is connected to the wire pull 4 to support the chain foot 9. The rotating shaft is installed with a spiral spring. The wire pull is stored on the wire wheel 5, which is installed on the non-bendable side of the one-way bending chain 2. In this embodiment, a one-way bending chain is adopted, and a two-way bending can also be adopted. The two sides cooperate with two wire wheels 5 to be used together for tensioning. The end of the pull wire 4 is connected to the chain foot 9 and tightened, and is closely attached to the non-bendable side of the one-way bending chain 2 through the wire pressing wheel 3. Two control motors (the first motor 14 and the second motor 10) respectively control the sprocket 6 and the wire wheel 5. Both motors control the sprocket 6 and the wire wheel 5 to rotate synchronously in opposite directions through self-locking mechanisms such as micro-turbine worms.

[0036] When the motor rotates, the one-way bending chain 2 and the pull wire 4 can be lowered or retracted synchronously, and the lowered chain is equal to the pull wire 4 in length, so the lowered chain is always pulled and cannot be bent or retracted, and the chain has the function of supporting weight. The worm gear can give the chain a self-locking function, and the chain can only be controlled by the motor to retract and release the chain, and the chain force cannot drive the motor to rotate, thereby reducing the workload of the motor. The chain guide 7 has the function of assisting the chain to straighten and prevent the chain from derailing, such as Figure 1 As shown, a partial chain guide 7 is also provided at the sprocket 6, and the gap between the chain guide 7 and the sprocket 6 constitutes a path for the one-way bending chain 2 to pass through, thereby confining the one-way bending chain 2 within the space.

[0037] The chain drone landing stand made of smaller density materials can be lifted and lowered over a longer range. The chain elongation, material and effective force area are determined by the weight of the drone and the maximum suspension force. The weight of an ordinary aerial photography drone is 200-450g. The chain foot force is not less than 1.2N. 2 For example, the effective force-bearing cross-sectional area of ​​the chain foot is 5mm 2 The material compressive strength only needs to meet 240MPa, which can be met by aluminum alloy, titanium alloy and other alloys. Taking a 1m long aluminum alloy chain as an example, its mass is less than 28g. In order to reduce weight, the casing is made of magnesium alloy, and the control motor uses a micro brushless servo reduction motor, which has a greater torque than the motor of the same volume.

[0038] Embodiment 2

[0039] Based on the drone landing bracket in the above-mentioned embodiment 1, this embodiment also provides a drone landing system, which includes an actuator and a control mechanism;

[0040] The actuator can be directly arranged inside the drone, or, as in the present embodiment, the actuator can be installed as a separate component under the drone. Figure 3As shown. The actuator is a lifting frame 1, and a one-way bending chain 2 is arranged inside the lifting frame 1. The one-way bending chain 2 is composed of a number of connecting blocks hinged in sequence, and the connecting blocks can slide relative to each other. The one-way bending chain 2 is driven to extend / retract in the UAV through a rotating mechanism; the one-way bending chain 2 includes a curling part and a supporting part, and the curling part is flexibly wound in the UAV. A chain foot 9 is arranged at the end of the upper supporting part, and the chain foot 9 is connected to a tensioning mechanism; the supporting part extends out of the UAV and is pulled and tensioned by the tensioning mechanism to form a rigid support, and the supporting part provides support force for the UAV; the number of the actuators is not less than the minimum points at which the UAV remains stable after landing. In this embodiment, four actuators are arranged on the UAV, and the actuators are respectively located at the four landing points of the UAV. The actuators can also be specifically arranged according to the landing points of the UAV according to the actual shape of the UAV;

[0041] The control mechanism (fuselage posture detection system) includes an inclination measurement sensor, an angular velocity sensor, a pressure sensor, a distance sensor and a controller. The inclination measurement sensor and the distance sensor are arranged inside the drone, and the pressure sensor and the distance sensor are arranged on the chain foot 9; the inclination measurement sensor, the angular velocity sensor, the pressure sensor, the distance sensor and the controller are connected, and the controller is connected to the rotor control motor and the actuator on the drone. The distance sensor can include an infrared distance sensor, an ultrasonic distance sensor, a laser distance sensor, etc. The drone's fuselage posture detection system can measure the data feedback such as the fuselage inclination angle and the flight altitude and control the rotor speed to adjust the drone's posture. The bottom of the chain foot is equipped with a pressure sensor and a distance sensor. When the UAV lands, the fuselage inclination angle, suspension height and other data are measured through the fuselage attitude detection system and fed back to the controller, which then controls the rotor speed to maintain horizontal suspension and lowers the chain feet at a fixed height. During the process of lowering the chain feet, the pressure value on the chain feet and the distance between the chain feet and the landing site are measured. When landing on uneven ground, the height of the chain feet at different positions on the landing bracket is adjusted accordingly to compensate for the height difference of the landing position, so that the UAV can take off and land smoothly on any ground.

[0042] The rotating mechanism includes a sprocket 6, which is connected to the first motor 14, and the sprocket 6 is meshed with the one-way bending chain 2; the one-way bending chain 2 extends outside the drone through a chain guide 7, and the chain guide 7 is arranged inside the drone, and the length of the chain guide 7 is equivalent to the length of the one-way bending chain 2 part tensioned by the tensioning mechanism inside the drone. The sprocket 6 and the wire wheel 5 are controlled by a micro motor (the first motor 14, the second motor 10), which can be a micro stepping motor, a micro servo motor or a micro DC reduction motor. The transmission between the sprocket 6, the wire wheel 5 and the motor is provided with a self-locking mechanism, so that the motor can control the chain foot to be retracted and released, and the chain foot cannot drive the motor to rotate. The self-locking mechanism can be a worm gear mechanism with a self-locking function.

[0043] The tensioning mechanism includes a wire wheel 5, on which a pull wire 4 is arranged, one end of the pull wire 4 is fixedly connected to the wire wheel 5, and the other end of the pull wire 4 passes through the chain guide 7 and is connected to the chain foot 9; the wire wheel 5 is connected to the second motor 10, and a wire pressing wheel 3 is arranged at the entrance end of the chain guide 7 and close to one side of the wire wheel 5, and the wire pressing wheel is in close contact with the pull wire 4, and the wire pressing wheel presses the pull wire 4 in the same direction as the force supported by the support part.

[0044] During the landing of the drone, the rotor speed is controlled by the feedback of the fuselage posture detection system. When the drone lands, the chain foot 9 obtains pressure corresponding to the rotor speed reduction process. The fuselage posture detection system detects the inclination of the drone, and then controls the rotor speed to maintain the horizontal suspension of the drone. When the landing bracket of the drone is extended and successfully landed, the control motor corresponding to the wire wheel 5 stops releasing the pull wire 4 and reverses to tighten the pull wire 4. The one-way bending chain 2 is tightened by the pull wire 4 and cannot be bent, so that it has a supporting function.

[0045] To detect whether the drone has landed successfully, a pressure sensor and a distance sensor are used for dual detection. When the chain foot 9 encounters an obstacle (such as a blade, etc.) that is not enough to bear the weight of the drone, the distance sensor detects that the chain foot contacts the obstacle and determines that the chain foot has landed. At this time, the pressure sensor assists in verification, and the chain foot 9 continues to be lowered. The obstacle cannot support the gravity of the drone, and it is determined that the chain foot 9 has not landed, and the chain foot 9 continues to be lowered; when the chain foot 9 contacts the landing site with complex terrain, and the contact point supporting the chain foot 9 avoids the detection range of the pressure sensor, the pressure sensor has not detected the pressure value and fails, and the distance sensor verification is required. The chain foot 9 continues to be lowered. When the distance sensor of the chain foot 9 detects that the distance between the chain foot 9 and the landing site no longer changes and the fuselage is tilted, it is determined that the drone chain foot 9 has successfully landed.

[0046] Embodiment 3

[0047] Based on the above-mentioned Embodiment 1 and Embodiment 2, this embodiment provides a method for landing a drone, including the following steps:

[0048] S1: Determine the landing position: The UAV evaluates the ground undulation data of the landing position during the landing process through the posture detection system in the fuselage, and evaluates the distance between the landing bracket on the UAV fuselage and the landing position. After determining the distance, the landing bracket is lowered according to the determined distance, and the distance sensor of the fuselage evaluates the distance between the UAV and the target object. After setting the distance h, the chain foot of the bracket is lowered at this height; the landing bracket is a lifting frame 1, and a one-way bending chain 2 is arranged in the lifting frame 1. The one-way bending chain 2 is composed of a plurality of connecting blocks hinged in sequence, and the two connecting blocks can slide relative to each other. The one-way bending chain 2 is driven to extend / retract to the UAV through a rotating mechanism; the one-way bending chain 2 includes a curling part and a supporting part, the curling part is flexibly wound in the UAV, and a chain foot 9 is arranged at the end of the upper supporting part, and the chain foot 9 is connected to a tensioning mechanism; the supporting part extends out of the UAV and is pulled and tensioned by the tensioning mechanism to form a rigid support, and the supporting part provides support force for the UAV;

[0049] S2: Lowering the supporting chain foot: The chain foot is lowered, and during the lowering process, the distance between the chain foot and the ground is continuously evaluated through the posture detection system in the fuselage. When the chain foot touches the ground, the final length of the chain foot is determined by the feedback of the pressure value in the posture detection system in the fuselage; the fuselage inclination angle and suspension height are detected by the fuselage posture detection system, and the rotation speed of the rotor is adjusted in real time to adjust the suspension force, so as to maintain the relative stability of the rotor suspension force and the sum of the pressure on the chain foot. The rotor rotation speed gradually decreases to maintain the horizontal landing of the drone; during the chain foot lowering and landing process, as the chain foot extends, the chain foot distance sensor detects that the distance from the chain foot to the ground gradually decreases until it touches the ground, and the chain foot gradually gains support force, and the pressure sensor detects the pressure value. The fuselage inclination angle and suspension height are detected by the fuselage posture detection system, and the rotation speed of the rotor is adjusted in real time to adjust the suspension force, so as to maintain the relative stability of the rotor suspension force and the sum of the pressure on the chain foot. As the chain foot pressure K gradually increases, the corresponding rotor speed gradually decreases, and the distance sensor to the chain foot detects that the distance between the chain foot and the ground is no longer decreasing, the rotor stops rotating and the chain foot pressure reaches the set critical value (if the weight of the drone is G and the number of chain feet is n, then it is G / n), and the chain foot stops lowering. Each landing bracket on the drone is controlled independently, and the chain is longer at the lower landing site and shorter at the higher landing site. This method uses the chain foot to compensate for the rugged ground and maintain the drone's horizontal landing.

[0050] S3: Fuselage posture adjustment: After the drone lands smoothly, the rotor stops rotating. The posture detection system in the fuselage evaluates the fuselage inclination data and feeds back to the central processor (controller) inside the drone. If the fuselage needs to be kept level, the central processor (controller) controls the one-way bending chain 2 in the landing bracket to extend / retract to eliminate the fuselage inclination; if the fuselage needs to have a certain inclination for operation, the landing brackets at different locations on the drone are controlled to extend / retract according to the required inclination, so that the drone is adjusted to the required inclination when the operation is required.

[0051] The posture detection system in the fuselage includes an inclination measurement sensor, a distance measurement sensor, a pressure sensor, a distance measurement sensor and a controller. The inclination measurement sensor and the distance measurement sensor are arranged inside the drone, and the pressure sensor and the distance measurement sensor are arranged on the chain foot 9; the inclination measurement sensor, the angular velocity sensor, the pressure sensor, the distance measurement sensor and the controller are connected, and the controller is connected to the rotor control motor and the actuator on the drone.

[0052] The drone posture detection system measures the inclination data of the fuselage through sensors such as inclination sensors or accelerometers and feeds back the data to the central processor. If the fuselage is detected to be tilted, the processor controls the sprocket control motor on the bracket to rotate and adjusts the chain foot height to eliminate the fuselage inclination. When operating, the drone controls all sprocket control motors to rotate synchronously to achieve the lifting and lowering of the drone in a balanced state. It can also control any sprocket control motor to rotate and change the height of any chain foot to adjust the drone's inclination and adjust it to the posture required for precise operation.

[0053] Embodiment 4

[0054] The patent is described in detail using the example of a quad-rotor drone, a quad-chain-legged drone stand, carrying microscopic imaging equipment, and accurately photographing the microscopic phenotype of a wheat plant in a wheat field.

[0055] The drone is equipped with a posture detection system, which has an inclination measurement sensor and an infrared sensor to detect the inclination of the fuselage and the flight altitude. A pressure sensor and an infrared sensor are installed at the chain foot 9 to detect the pressure on the chain foot and the distance from the chain foot to the landing site. When the drone needs to shoot the microscopic phenotype of the target wheat, the infrared sensor on the fuselage measures the distance from the drone to the highest point of the wheat; when maintaining this height relatively stable, the infrared sensor on the chain foot measures the distance from the chain foot to the ground to provide a reference for the length of the chain foot.

[0056] The drone flies to 10 to 20 cm above the wheat and keeps it level. The infrared sensor on the fuselage detects the distance between the drone and the wheat and maintains this height. At this time, the force on the drone is the suspension force generated by the rotation of the rotor, and the suspension force of each rotor is equal. After the drone is suspended, it starts to control the motor to lower the chain feet of the landing bracket. There is a chain foot 9 in the corresponding direction of each rotor. When the chain foot 9 does not touch the object, the unidirectional bending chain 2 continues to be lowered.

[0057] If any chain foot 9 touches obstacles such as wheat leaves, the chain foot 9 is subjected to the force from the leaves, the infrared sensor detects that the chain foot 9 has landed, the pressure sensor detects the pressure value, and the rotor at the corresponding position of the drone reduces the speed to reduce the suspension force. At this time, the suspension force of the rotor and the sum of the support force of the chain foot 9 remain relatively stable (if the weight of the drone G is 400g, the sum of the suspension force and the support force is about 0.98N). The chain foot 9 is continuously lowered to increase the pressure on the chain foot 9. Since the plant leaves are not enough to support the gravity of the drone, the force value detected by the chain foot 9 pressure sensor is less than the limit force for the chain foot to stop lowering. It is determined that the infrared sensor detects that the landing data is invalid. The sprocket 6 continues to rotate to drive the chain foot to lower, passing through the obstructing plant leaves. The infrared sensor re-detects the data, and the pressure sensor no longer detects the pressure value. At this time, the rotor speed corresponding to the chain foot 9 is accelerated again to increase the suspension force of the rotor to maintain the horizontal suspension of the drone.

[0058] When a chain foot 9 is lowered and touches the ridge, the infrared sensor of this chain foot 9 detects that the chain foot has landed, and the pressure sensor detects pressure again. In order to maintain the smooth landing of the UAV, the corresponding rotor reduces the rotation speed and the suspension force of the rotor is reduced; while the infrared sensor and pressure sensor of the chain foot that does not touch the ridge detect that the chain foot 9 has not landed, and the one-way bending chain 2 continues to be lowered. When the chain foot 9 that touches the ridge does not reach the set critical pressure value (the critical value is 1 / 4 of the weight of the UAV, and the rotor no longer provides suspension force for the horizontal level of the UAV), the one-way bending chain 2 continues to be lowered, the infrared sensor detects that the distance between the chain foot 9 and the landing point remains unchanged, and the pressure sensor detection value pressure continues to increase. In order to maintain the horizontal level of the UAV, the corresponding rotor speed is reduced until the pressure sensor detects that the pressure of the chain foot 9 reaches the critical value, and it is determined that the chain foot 9 has landed, and the sprocket 6 controls the motor to stop rotating, and the chain foot 9 stops being lowered. The chain foot 9 that has not landed on the ridge continues to be lowered when it does not touch the ground. When the distance sensor detects that the chain foot 9 touches the ground, the pressure on the chain foot 9 gradually increases to a critical value, and the corresponding rotor speed gradually decreases until it no longer provides suspension force for the drone. During this process, the drone's suspension height remains unchanged, and the tilt information of the drone is detected in real time through the tilt angle measurement sensor on the drone, and the rotor speed is adjusted accordingly to eliminate the fuselage tilt angle.

[0059] After the drone lands, the drone starts the tilt detection program, that is, the tilt measurement sensor detects the tilt of the fuselage. If the tilt measurement sensor detects that the fuselage is tilted, the sprocket motor is controlled to rotate, and the height of the chain foot 9 is changed to eliminate the tilt of the fuselage. If the fuselage is detected to be tilted to the left, the height of the left chain foot 9 is increased accordingly; if the fuselage is detected to be tilted to the right, the height of the right chain foot 9 is increased accordingly, so as to adjust the drone to a horizontal state.

[0060] After the drone has landed safely and adjusted its level, it is necessary to adjust the drone to a suitable position to shoot the microscopic phenotype of the plant. The height of the drone is adjusted by controlling all sprockets 6 to rotate synchronously. If it is necessary to shoot the microscopic phenotype of the plant at an angle, the height of any chain foot 9 can also be controlled to tilt the drone, and the tilt angle is detected by the inclination angle measurement sensor. During the process of shooting the microscopic phenotype of the plant by the drone, the drone and the chain foot of the bracket do not undergo mechanical movement, so the drone can be equipped with microscopic imaging equipment to accurately shoot the microscopic phenotype of the plant.

[0061] After the drone's microscopic operation is completed, the rotor is started to increase the suspension force and the drone takes off. After take-off, the sprocket controls the motor to rotate and control each chain foot of the landing bracket to rise to the initial position.

[0062] Embodiment 5

[0063] The patent is described in detail using a quad-rotor drone, a four-chain-legged drone stand, and a sampling manipulator to collect stamen samples from hillside plants as an example.

[0064] The drone is equipped with a posture detection system, which has an inclination sensor and an infrared sensor to detect the inclination of the fuselage and the flight altitude. The chain foot 9 is equipped with a pressure sensor and an infrared sensor to detect the pressure on the chain foot 9 and the distance from the chain foot to the landing site. When the drone needs to sample the stamens of the hillside plants, the infrared sensor on the fuselage measures the distance from the drone to the highest point of the target plant; when this altitude is maintained relatively stable, the infrared sensor on the chain foot 9 measures the distance from the chain foot 9 to the ground, giving a reference for the length of the chain foot 9 to be lowered.

[0065] The drone flies to 10 to 20 cm above the plant and keeps it level. The infrared sensor on the fuselage detects the distance from the drone to the highest point of the plant and maintains this height. At this time, the force exerted on the drone is the suspension force generated by the rotation of the rotor, and the suspension force of each rotor is equal. Before the chain foot 9 is lowered, the infrared sensor of each chain foot detects the distance to the landing point, which serves as a reference for the chain foot lowering distance. The drone controls the motor to lower the chain foot of the landing bracket. There is a chain foot in the corresponding direction of each rotor. When the chain foot and the infrared sensor detect that the chain foot does not touch the object, the unidirectional bending chain 2 continues to be lowered.

[0066] Since the hillside is a non-horizontal area, when the drone lands, the chain foot 9 contacts the landing site at different times and at different heights. The infrared sensor of the chain foot 9 at the top of the hillside first detects that the chain foot has landed, and the pressure sensor begins to detect the pressure to determine whether the chain foot 9 has landed. In order to maintain the drone's smooth landing, the corresponding rotor reduces the speed so that the sum of the rotor suspension force and the chain foot support force remains relatively stable, and the entire landing process is kept horizontal. After the infrared sensor of the chain foot 9 detects that the chain foot has landed, when the chain foot 9 at the top of the hillside does not reach the set critical pressure value, the one-way bending chain 2 continues to be lowered, the pressure sensor detection value pressure continues to increase, and the corresponding rotor speed continues to decrease until the pressure sensor detects that the chain foot pressure reaches the critical value, and it is determined that the chain foot 9 has landed, and the sprocket 6 controls the motor to stop, and the chain foot stops being lowered.

[0067] The infrared sensor of the chain foot at the lower part of the hillside detects that the chain foot 9 has not landed, and the corresponding one-way curved chain 2 continues to be lowered. When it touches the hillside support point, the infrared sensor of the chain foot detects that the chain foot has landed, and the chain foot continues to be lowered so that the pressure on the chain foot gradually increases to a critical value, and the corresponding rotor speed gradually decreases until it no longer provides suspension force for the drone, and the chain foot stops being lowered. During this process, the drone's suspension height remains unchanged, and the tilt information of the drone is detected in real time through the tilt sensor on the drone, and the rotor speed is adjusted accordingly to eliminate the fuselage tilt.

[0068] After the drone lands, the drone starts the tilt detection program, that is, the tilt sensor detects the tilt of the fuselage. If the tilt sensor detects that the fuselage is tilted, the sprocket motor is controlled to rotate, and the height of the chain foot is changed to eliminate the tilt of the fuselage. If the fuselage is detected to be tilted to the left, the height of the left chain foot is increased accordingly; if the fuselage is detected to be tilted to the right, the height of the right chain foot is increased accordingly, so as to adjust the drone to a horizontal state.

[0069] After the drone has landed steadily and adjusted its level, it is necessary to adjust the drone to a suitable posture to obtain samples from the stamens of the target plants. The height of the drone is adjusted by controlling the synchronous rotation of all sprockets. By controlling the height of any chain foot, the inclination of the drone is adjusted to achieve a suitable posture for collecting samples. The inclination information is measured by the inclination measurement sensor. During the process of drone microscopic collection of plant stamen samples, the drone and the bracket chain foot do not undergo mechanical movement, and there is no body shaking and rotor wind interference. Therefore, the drone can be equipped with microscopic sample collection equipment for sample collection.

[0070] The embodiments described above are only descriptions of the preferred modes of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations, modifications, and substitutions made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for landing a drone, characterized in that: The following steps are involved: S1: Determine the landing position: the drone evaluates the ground undulation data of the landing position during the landing process through the posture detection system in the fuselage, and evaluates the distance between the landing brackets on the drone fuselage and the landing position. After determining the distance, the landing bracket is lowered according to the determined distance; the landing bracket is a lifting frame (1), and a one-way bending chain (2) is arranged in the lifting frame (1). The one-way bending chain (2) is composed of a plurality of connecting blocks hinged in sequence, and the connecting blocks can slide relative to each other. The one-way bending chain (2) is driven to extend / retract to the drone through a rotating mechanism; the one-way bending chain (2) includes a curling part and a supporting part, the curling part is flexibly wound in the drone, and a chain foot (9) is arranged at the end of the supporting part, and the chain foot (9) is connected to a tensioning mechanism; the supporting part extends out of the drone and is pulled and tensioned by the tensioning mechanism to form a rigid support, and the supporting part provides support force for the drone; S2: Lowering the supporting chain foot: The chain foot is lowered, and during the lowering process, the distance between the chain foot and the ground is continuously evaluated through the posture detection system in the fuselage. When the chain foot touches the ground, the final length of the chain foot is determined by the feedback of the pressure value in the posture detection system in the fuselage. The fuselage inclination angle and suspension height are detected by the fuselage posture detection system, and the rotor speed is adjusted in real time to adjust the suspension force, so as to maintain the relative stability of the rotor suspension force and the sum of the pressure on the chain foot. The rotor speed is gradually reduced to maintain the horizontal landing posture of the UAV. S3: Body posture adjustment: After the drone lands smoothly, the posture detection system in the body evaluates the body inclination data and feeds back to the controller inside the drone. If the body needs to remain level, the central processor controls the one-way bending chain (2) in the landing bracket to extend / retract to eliminate the body inclination. If the body needs to have a certain inclination for operation, the landing brackets at different locations on the drone are controlled to extend / retract according to the required inclination, so that the drone can be adjusted to the required inclination when the operation is required.

2. The method for landing a drone according to claim 1, characterized in that: The posture detection system in the fuselage comprises an inclination measurement sensor, an angular velocity sensor, a pressure sensor, a distance sensor and a controller, wherein the inclination measurement sensor and the distance sensor are arranged inside the drone, and the pressure sensor and the distance sensor are arranged on a chain foot (9); the inclination measurement sensor, the distance sensor, the pressure sensor, the distance sensor and the controller are connected, and the controller is connected to a rotor control motor and an actuator on the drone.

Images