Deformable unmanned aerial vehicle and control method thereof

Abstract

The deformable unmanned aerial vehicle comprises a vehicle body and four rotor wing mechanisms fixed to the vehicle body, one end of each rotor wing mechanism is hinged to the vehicle body, and the other end of each rotor wing mechanism is provided with a propeller mechanism; a sliding block limiting mechanism for driving the four rotor wing mechanisms to synchronously rotate is arranged on the aircraft body, and the sliding block limiting mechanism is used for driving the four rotor wing mechanisms to synchronously fold towards the inner side. The method further comprises the steps of control methods from S1 to S5. The deformable unmanned aerial vehicle can adapt to various complex flight environment working conditions, has good flexibility and maneuverability, adopts the mechanism principle similar to an umbrella, designs the rotors capable of moving up and down to adapt to different flight environments, and better completes various flight tasks. The deformable unmanned aerial vehicle is a four-rotor variable mechanism unmanned aerial vehicle which can automatically deform, autonomously plan a path and automatically sail, and efficient self-adaptive flight of the unmanned aerial vehicle in a complex environment is achieved.

Description

Technical Field

[0001] The present invention relates to the field of robotics technology, and in particular to a deformable unmanned aerial vehicle and a control method thereof. Background Art

[0002] Unmanned vehicles can be used to perform military or civilian applications such as monitoring, reconnaissance, and exploration. Unmanned vehicles can be equipped with functional payloads, such as sensors for collecting environmental data. For example, remote-controlled unmanned aerial vehicles, including fixed-wing and rotary-wing aircraft, can be used to provide aerial imagery of otherwise inaccessible environments.

[0003] Traditional quad-rotor drones mostly use the classic X-shaped quad-rotor mode, in which the drone body is rigidly connected to the motor and propeller mechanism through a connecting rod. Traditional quad-rotor drones can maintain good stability, but the drone rotors are in an immobile state, making the overall size of the drone relatively large and not well suited for a variety of complex working environments. Often, due to the large size of their own rotors, they are unable to work by crossing obstacles and are limited by the flight environment. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a deformable UAV and a control method thereof.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0006] Provided are a deformable UAV and a control method thereof, comprising an airframe and four rotor mechanisms fixed on the airframe, wherein one end of the rotor mechanism is hinged to the airframe, and the other end is provided with a propeller mechanism; a slider limiting mechanism is provided on the airframe for driving the four rotor mechanisms to rotate synchronously, and the slider limiting mechanism is used for driving the four rotor mechanisms to be synchronously retracted inwards.

[0007] Furthermore, each rotor mechanism includes two upper connecting rods, two lower connecting rods and a linkage rod. The two upper connecting rods are fixedly connected to form an upper support arm, and the two lower connecting rods are fixedly connected to form a lower support arm. One end of the upper support arm and the lower support arm are connected through a motor compartment support frame. The motor compartment support frame is used to install the propeller mechanism. The other end of the upper support arm is hinged to the body through a fourth pin shaft, and the other end of the lower support arm is hinged to the body through a second pin shaft. One end of the linkage rod is hinged to the lower support arm through a first pin shaft, and the other end is hinged to the slider limiting mechanism through a third pin shaft.

[0008] Furthermore, the two upper connecting rods are fixedly connected via two first reinforcing connecting plates, and the two lower connecting rods are fixedly connected via two second reinforcing connecting plates.

[0009] Furthermore, the propeller mechanism includes a motor, a propeller and a barrel-shaped motor cabin, the propeller is fixed to the output end of the motor, the motor is fixed in the motor cabin, and the motor cabin is fixedly connected to the rotor mechanism through two first bolts and two second bolts.

[0010] Furthermore, the body includes an upper top plate and a bottom support plate, the upper top plate and the bottom support plate are fixedly connected by four positioning columns, and eight structural pillars are arranged between the upper top plate and the bottom support plate, and every two structural pillars are used to rotatably connect the rotor mechanism, and the structural pillars are hinged to the rotor mechanism; two frame legs are fixed to the bottom of the bottom support plate.

[0011] Furthermore, a middle partition is fixed at the bottom of the four structural pillars, and the middle partition is used to limit the slider limiting mechanism.

[0012] Furthermore, the slider limiting mechanism includes a cross-shaped central slider and a slider electric cylinder that drives the central slider to move vertically. The four side ends of the central slider are hinged to the rotor mechanism. The four side ends of the central slider are provided with guide holes. The bottom of the slider electric cylinder is fixed on the machine body, and the telescopic end of the slider electric cylinder is fixedly connected to the central slider.

[0013] Furthermore, it also includes a control system, which includes a power module, a flight control module, a GPS module, a three-dimensional depth recognition camera, a UAV dynamics module and a motor drive module. The power module is electrically connected to the flight control module, the GPS module, the three-dimensional depth recognition camera, the UAV dynamics module and the motor drive module are all electrically connected to the flight control module, and the three-dimensional depth recognition camera is arranged at the bottom of the body.

[0014] A control method for a deformable drone comprises the following steps:

[0015] S1: Before the flight mission begins, set the initial position of the drone and the initial position of the destination in the flight control module, and use the flight control module to set the flight path and flight altitude; the initial position includes longitude and latitude, the upper and lower limits of the flight altitude during the flight process, the upper limit of the flight speed, and the longitude, latitude and altitude of the destination;

[0016] S2: After the flight mission begins, the motor starts working, the drone rises to the set flight altitude, and then flies above the destination coordinates; during the flight, the 3D depth recognition camera identifies the front of the drone, and the flight control module controls whether the drone automatically avoids obstacles and bypasses;

[0017] S3: After arriving at the destination coordinates, the drone performs coordinate calibration. After confirming that its own position coordinates are consistent with the set destination coordinates, it hovers at the set target height to perform the flight mission;

[0018] S4: After the drone completes the mission at the destination, it returns to the destination.

[0019] S41: swapping the coordinates of the initial position of the drone and the initial position of the destination set in step S1, and starting the return mission, the process is the same as step S2;

[0020] S42: After returning to the initial position coordinates of the drone, the slider electric cylinder starts working to put the drone in an unfolded posture;

[0021] S43: The 3D depth recognition camera looks down to identify whether there are obstacles during the landing process. If no obstacles are identified below the drone, it will land slowly at the lowest speed; if no obstacles are identified below the drone, the landing position coordinates will be changed to avoid obstacles;

[0022] S44: After landing, the motor stops working, the slider electric cylinder returns to the initial state, and the four rotor mechanisms return to the initial state;

[0023] S5: Repeat steps S1-S4 to complete the next flight mission.

[0024] Furthermore, in step S2, the drone uses the three-dimensional depth recognition camera in conjunction with the flight control module to achieve obstacle avoidance and detour as follows:

[0025] S21: Establish a three-dimensional spatial coordinate system using the center of mass of the deformable drone as the coordinate origin;

[0026] S22: The 3D depth recognition camera collects images in front of the drone frame by frame, and the flight control module determines obstacles based on the collected images.

[0027] S23: The flight control module selects normal flight or proceeds to the next step according to the proportion of obstacles in the left and right anchor frames;

[0028] S24: The flight control module selects the hovering mode or automatic obstacle avoidance and detour according to the ratio of the obstacles on the left and right sides to the area of ​​the anchor frame. If automatic obstacle avoidance and detour is selected, the next step is performed.

[0029] S25: The flight control module adjusts the thrust control constants of several propellers according to the proportion of the left and right anchor frames to achieve obstacle avoidance and detour.

[0030] The beneficial effects of the present invention are:

[0031] The deformable UAV of the present invention can change the horizontal position of the rotor and the overall size of the UAV according to the working environment during the operation of the UAV. It has good flexibility and maneuverability while maintaining stability and is suitable for a variety of different working environments.

[0032] The deformable UAV of the present invention can adapt to a variety of complex flight environments and working conditions, has good flexibility and maneuverability, adopts an umbrella-like mechanism principle, and is designed with rotors that can move up and down to adapt to different flight environments and better complete various flight missions.

[0033] Compared with the traditional four-rotor UAV, the present invention has a simple mechanical structure, low production cost, and is suitable for different flight environments, that is, a four-rotor UAV with high flexibility and strong maneuverability. The mechanism principle of an umbrella is adopted, the rotor is improved into a movable form, and a central movable connecting plate is added, which is like the skeleton of an umbrella.

[0034] The unmanned robot of the present invention is a four-rotor variable mechanism drone that can automatically transform, autonomously plan paths, and automatically navigate, thereby realizing efficient adaptive flight of drones in complex environments. Traditional four-rotor drones mostly adopt the classic X-shaped four-rotor mode, in which the drone fuselage is rigidly connected to the motor and propeller mechanism through a connecting rod. This mode can maintain good stability, but it also causes the disadvantage of the overall size of the drone being too large. It can complete the work well in open places, but it is subject to many restrictions in the face of a changeable and complex environment. Therefore, based on this reason and drawing on the structural design of traditional four-rotors, the mechanism principle of an umbrella is adopted, and the four-rotor mechanism is designed to be movable. The four-rotor mechanism can move up and down according to the working environment to change the overall size of the drone, improve the maneuverability and flexibility of the drone, and enable it to adapt to different flight environments and mission requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The overall structure of the deformable UAV of the present invention is shown in FIG. Figure 1 ;

[0036] Figure 2 The overall structure of the deformable UAV of the present invention is shown in FIG. Figure 2 ;

[0037] Figure 3 This is a schematic diagram of the structure of the deformable UAV of the present invention without the control system part;

[0038] Figure 4 It is a schematic diagram of the structure of the rotor mechanism and the propeller mechanism;

[0039] Figure 5 Schematic diagram of the slider limit mechanism and the body structure Figure 1 ;

[0040] Figure 6 Schematic diagram of the slider limit mechanism and the body structure Figure 2 ;

[0041] Figure 7It is a schematic diagram of the structure of the rotor mechanism, propeller mechanism, slider limit mechanism and fuselage;

[0042] Figure 8 for Figure 7 A partial enlarged view of the middle A;

[0043] Fig. 9 This is a schematic diagram of the distribution of propellers at four locations;

[0044] Fig.10 Flowchart of propeller control for drone to avoid obstacles.

[0045] The main components in the figure are described as follows:

[0046] 1. Rotor mechanism; 11. Upper connecting rod; 12. Lower connecting rod; 13. Linkage rod; 14. Motor cabin support frame; 15. First reinforcement connecting plate; 16. Second reinforcement connecting plate; 17. First pin shaft; 18. Second pin shaft; 19. Third pin shaft; 10. Fourth pin shaft;

[0047] 2. Propeller mechanism; 21. Propeller; 22. Motor compartment; 23. Motor; 24. First bolt; 25. Second bolt;

[0048] 3. Machine body; 31. Upper plate; 32. Positioning column; 33. Bottom support plate; 34. Middle partition; 35. Structural pillar; 36. Frame leg;

[0049] 4. Slider limit mechanism; 41. Center slider; 42. Slider electric cylinder;

[0050] 5. Control system; 51. Three-dimensional depth recognition camera. DETAILED DESCRIPTION

[0051] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0052] like Figure 1 , 2 As shown in FIG. 3 , the deformable UAV includes a body 3 and four rotor mechanisms 1 fixed on the body 3. One end of each rotor mechanism 1 is hinged to the body 3, and the other end is provided with a propeller mechanism 2. The body 3 is provided with a slider limit mechanism 4 that drives the four rotor mechanisms 1 to rotate synchronously. The slider limit mechanism 4 is used to drive the four rotor mechanisms 1 to fold inward synchronously, so that the shape of the UAV becomes slender and easy to pass through narrow airspace with obstacles.

[0053] like Figure 4 As shown, the rotor mechanism 1 includes two parallel upper connecting rods 11, two parallel lower connecting rods 12 and a linkage rod 13. The two parallel upper connecting rods 11 are fixedly connected to form an upper support arm, and the two parallel lower connecting rods 12 are fixedly connected to form a lower support arm. One end of the upper support arm and the lower support arm are connected through a motor compartment support frame 14. The motor compartment support frame 14 is used to install the propeller mechanism 2. The other end of the upper support arm is hinged to the body 3 through a fourth pin shaft 10, and the other end of the lower support arm is hinged to the body 3 through a second pin shaft 18. One end of the linkage rod 13 is hinged to the lower support arm through a first pin shaft 17, and the other end is hinged to the slider limit mechanism 4 through a third pin shaft 19. The two linkage rods 13 connect the movement of the rotor with the slider limit mechanism 4, and the movement of the linkage rod 13 is controlled by the slider limit mechanism 4, thereby controlling the synchronous up and down movement of the four rotor mechanisms 1. In this embodiment, two linkage rods 13 are provided on each rotor mechanism 1, and each linkage rod 13 is hinged with a connecting rod 12, and the two linkage rods 13 are connected to the rotor mechanism 1 and the slider limit mechanism 4 by force. The rotor mechanism 1 adopts a double parallel connecting rod connection method to ensure the stability of the motor placement, and the propeller direction is always vertically upward. The two pairs of parallel connecting rods are cleverly connected by a hollow support plate, which reduces the overall weight of the drone and enables the shaft rod part to evenly disperse the force when subjected to external force, thereby improving the structural strength and stability of the drone. The two upper connecting rods 11 are fixedly connected by two first reinforcement connecting plates 15, and the two lower connecting rods 12 are fixedly connected by two second reinforcement connecting plates 6. The first reinforcement connecting plate 15 and the first reinforcement connecting plate 15 ensure the structural strength and movement stability of the rotor, and improve the structural rigidity of the rotor. The specific working principle is as follows: one end of the upper connecting rod 11 and the lower connecting rod 12 is hinged to the body 3, and one end of the linkage rod 13 is hinged to the lower connecting rod 12. By controlling the slider limit mechanism 4 to move up and down, the distal ends of the four rotor mechanisms 1 are driven to retract inward, thereby changing the body shape of the UAV, making the UAV body shape become slender, and more convenient to pass through narrow obstacle airspace.

[0054] The propeller mechanism 2 includes a motor 23, a propeller 21 and a barrel-shaped motor compartment 22. The propeller 21 is fixed to the output end of the motor 23, and the motor 23 is fixed in the motor compartment 22. The motor compartment 22 is fixedly connected to the rotor mechanism 1 through two first bolts 24 and two second bolts 25. The rotor mechanism 1 adopts a double parallel connecting rod connection method to ensure the stability of the motor placement, and the propeller direction is always vertically upward. The two pairs of parallel connecting rods are cleverly connected by a hollow support plate, which reduces the overall weight of the drone and enables the shaft part to evenly disperse the force when subjected to external force, thereby improving the structural strength and stability of the drone.

[0055] like Figure 5 and 6As shown, the fuselage 3 includes an upper top plate 31 and a bottom support plate 33. The upper top plate 31 and the bottom support plate 33 are fixedly connected by four positioning columns 32. Eight structural pillars 35 are also arranged between the upper top plate 31 and the bottom support plate 33. Every two structural pillars 35 are used to rotate and connect the rotor mechanism 1. The structural pillars 35 are hinged with the rotor mechanism 1. The structural pillars 35 are provided with upper hinge holes that cooperate with the fourth pin shaft 10 and lower hinge holes that cooperate with the second pin shaft 18. Two frame legs 36 are fixed at the bottom of the bottom support plate 33. An intermediate partition 34 is fixed at the bottom of the four structural pillars 35. The intermediate partition 34 is used to limit the slider limit mechanism 4. The fuselage 3 is divided into two layers, the upper layer is placed with key control components such as the flight control module, the numerical control board, and the GPS module, and the lower layer is the core area of ​​structural deformation. In this core area, the slider limit mechanism 4 can move up and down according to a specific track constrained by constraints to achieve rapid deformation and adjustment of the drone structure.

[0056] like Figure 7 and 8 As shown, the slider limiting mechanism 4 includes a cross-shaped central slider 41 and a slider electric cylinder 42 that drives the central slider 41 to move vertically. The four side ends of the central slider 41 are hinged with the rotor mechanism 1. The four side ends of the central slider 41 are provided with guide holes that cooperate with the positioning column 32. The bottom of the slider electric cylinder 42 is fixed on the body 1, and the telescopic end of the slider electric cylinder 42 is fixedly connected to the central slider 41. Specific working principle: the telescopic end of the slider electric cylinder 42 drives the central slider 41 to slide up and down. Under the guidance of the positioning column 32, the central slider 41 drives the linkage rods 13 on the four rotor mechanisms 1 to move up and down, so that the linkage rods 13 are used to drive the lower arm of the rotor mechanism 1 to rotate, thereby realizing the inward retraction of the four rotor mechanisms 1. In order to ensure that the quadcopter always stays on the same horizontal plane during the movement and maintain the stability of the drone movement, a slider limit mechanism 4 is designed. The positioning column 32 determines the movement trajectory of the center slider 41; it is connected to the four rotor mechanisms by a pin shaft, and the slider electric cylinder 42 controls the reciprocating motion of the four rotor mechanisms, so that the four rotor mechanisms move up and down within the travel range. At the same time, the upper top plate 31 and the middle partition plate 34 will limit the upper and lower limit positions of the center slider 41 to ensure that it is in the correct range of motion.

[0057] It also includes a control system 5, which includes a power module, a flight control module, a GPS module, a three-dimensional depth recognition camera 51, a drone dynamics module and a motor drive module. The power module is electrically connected to the flight control module, and the GPS module, the three-dimensional depth recognition camera 51, the drone dynamics module and the motor drive module are all electrically connected to the flight control module. The three-dimensional depth recognition camera 51 is arranged at the bottom of the body 1. The flight control module is preferably provided with a display screen, for example, a Ledi OSD module. The drone dynamics module is responsible for calculating and updating various key information of the drone according to the input force and torque, including position, speed, attitude and angular velocity, etc. When the drone is subjected to the action of an external force, the module will receive the data of the external force, and then combine the physical properties of the drone to deduce the motion state of the drone under the action of these forces. The drone dynamics module is responsible for calculating and updating various key information of the drone according to the input force and torque, including position, speed, attitude and angular velocity, etc. When the drone is subjected to the action of an external force, the module will receive the data of the external force, and then combine the physical properties of the drone to deduce the motion state of the drone under the action of these forces. In addition, the control system also includes a position controller and an attitude controller. The main task of the position controller is to ensure that the drone can move to the specified position accurately and stably; the attitude controller consists of two parts, the inner loop is responsible for controlling the angular velocity, and the outer loop is responsible for controlling the angle. This strategy ensures that the drone can respond to operating instructions stably and accurately whether it is hovering, cruising or performing complex maneuvers. The GPS module is responsible for providing the drone's latitude and longitude information, the visual acquisition and analysis module is responsible for obstacle avoidance during the flight process, and the flight control module is the core of the drone's control system. All information is collected here and fed back to the drone to make a response plan.

[0058] The control method of the deformable UAV comprises the following steps:

[0059] S1: Before the flight mission begins, set the initial position of the drone and the initial position of the destination in the flight control module, and use the flight control module to set the flight path and flight altitude; the initial position includes longitude and latitude, the upper and lower limits of the flight altitude during the flight process, the upper limit of the flight speed, and the longitude, latitude and altitude of the destination;

[0060] S2: After the flight mission begins, the motor 23 starts working, the drone rises to the set flight altitude, and then flies above the destination coordinates; the flight coordinates and flight parameters such as speed and altitude of the drone are displayed in real time in the map of the flight control module. During the flight, the three-dimensional depth recognition camera 51 recognizes the front of the drone, and the flight control module controls whether the drone automatically avoids obstacles; the recognition work specifically includes acquiring images, gridding the images, and mapping them into grids in three-dimensional space. This part is a prior art and will not be repeated here; the specific principle of automatic obstacle avoidance by the drone: the position of the obstacles in the identified anchor frame and the obstacles in front of the mark are obtained, the relative position data with the drone is obtained, the position information is transmitted to the control system, and the side with fewer obstacles is selected to control the motor 23 to move in the x or y axis direction; for example, if there are too many obstacles on the right side, the power of the two motors 23 on the right side is increased, the two propellers on the right side obtain greater lift, and the drone moves to the left; under normal circumstances, no movement in the z-axis direction is performed to avoid obstacles; if there are too many obstacles in the identified anchor frame and autonomous obstacle avoidance cannot be performed, a hovering command is issued, waiting for the operator to take over;

[0061] S3: After arriving at the destination coordinates, the drone performs coordinate calibration. After confirming that its own position coordinates are consistent with the set destination coordinates, it hovers at the set target height to perform the flight mission;

[0062] S4: After the drone completes the mission at the destination, it returns to the destination.

[0063] S41: swapping the coordinates of the initial position of the drone and the initial position of the destination set in step S1, and starting the return mission. The process is the same as step S2. Specifically, the drone rises to the set flight altitude corresponding to the initial position of the destination, and then flies to the set flight altitude corresponding to the initial position of the drone.

[0064] S42: After returning to the initial position coordinates of the drone, the slider electric cylinder 42 starts to work, controlling the four rotor mechanisms 1 to unfold, so that the drone is in an unfolded posture, forming a shape similar to an umbrella;

[0065] S43: The three-dimensional depth recognition camera 51 identifies whether there are obstacles during the landing process. If no obstacles are identified below the drone, the drone will land slowly at the lowest speed; if no obstacles are identified below the drone, the landing position coordinates will be changed to avoid obstacles;

[0066] S44: After landing, the motor 23 stops working, the slider electric cylinder 42 returns to the initial state, and the four-way rotor mechanism 1 returns to the initial state;

[0067] S5: Repeat steps S1-S4 to complete the next flight mission;

[0068] In step S2, the method for the drone to avoid obstacles is as follows:

[0069] S21: Taking the center of mass of the deformable UAV as the coordinate origin, a spatial three-dimensional coordinate system is established; specifically, the direction facing the three-dimensional recognition camera is the positive direction of the x-axis, the right side of the three-dimensional recognition camera is the positive direction of the y-axis, and the upper side of the UAV is the positive direction of the z-axis;

[0070] S22: The three-dimensional depth recognition camera 51 collects images in front of the drone frame by frame, and the flight control module determines obstacles on the collected images; in the present invention, the detection distance of the three-dimensional depth recognition camera 51 is 15 meters;

[0071] S23: The flight control module selects normal flight or proceeds to the next step according to the proportion of obstacles in the left and right anchor frames. Specifically, during the flight, the three-dimensional depth recognition camera 51 detects the obstacles in front of it frame by frame (the positive direction of the x-axis in the figure), and divides the left and right sides of the image recognition anchor frame into two areas α and β. The proportions of the obstacle areas in the α area and the β area are A and B respectively. The control process is as follows: Fig.10 , specifically:

[0072] If A≥10%S or B≥10%S is satisfied, S is the area of ​​the entire image recognition anchor frame, and the flight control module determines that obstacle avoidance is required, and controls the slider electric cylinder 42 to move, changing the drone to a folded state, and proceeding to the next step;

[0073] If A<10%S or B<10%S, the drone will continue to fly normally without changing its flight attitude;

[0074] S24: The flight control module selects to enter the hovering mode or automatically bypass the obstacle according to the ratio of the left and right obstacles to the anchor frame area. If automatic obstacle avoidance is selected, proceed to the next step. Specifically:

[0075] If A+B≥75%S is satisfied, the drone enters the hovering mode and sends a signal to the flight control system, waiting for the operator to take over; if there is an obstacle only in the α area or the β area, it is necessary to avoid the obstacle and bypass it, then the k2 and k3 values ​​are adjusted synchronously to increase the motor thrust of propeller 2 and propeller 3, so that the drone moves in the positive direction of the y axis until the 3D depth recognition camera 51 recognizes that the area ratio of the obstacle in front meets A<10%S or B<10%S, at which time the motor thrust of propeller 2 and propeller 3 returns to the normal flight speed and the drone flies normally;

[0076] If A+B<75%S, and obstacles are recognized in both areas α and β, compare the sizes of A and B and proceed to the next step;

[0077] S25: The flight control module adjusts the propeller 1 thrust control constant k1, propeller 2 thrust control constant k2, propeller 3 thrust control constant k3, propeller 4 thrust control constant k4 according to the size of A and B, so as to avoid obstacles and bypass them. Specifically:

[0078] If A≥B, the values ​​of k2 and k3 are adjusted synchronously to increase the thrust of propeller 2 and propeller 3 motors, so that the drone moves a certain distance in the positive direction of the y-axis until the three-dimensional depth recognition camera 51 recognizes that the area ratio of the obstacle in front satisfies A<10%S or B<10%S. At this time, the thrust of propeller 2 and propeller 3 motors returns to normal flight speed and the drone flies normally.

[0079] If A<B, then adjust the values ​​of k1 and k4 synchronously, increase the thrust of propeller 1 and propeller 4 motors, and move the drone in the negative direction of the Y axis for a distance until the three-dimensional depth recognition camera 51 recognizes that the area ratio of the obstacle in front meets A<10%S or B<10%S, at which time the thrust of propeller 1 and propeller 4 motors returns to normal flight speed and the drone flies normally;

[0080] In this control method, the thrust control constant k corresponding to the propeller is combined with the motor power value distribution model to distribute the power control of the four motors: the deformable drone adopts an X-shaped frame, such as Fig. 9 , the motor power value distribution model used is as follows:

[0081]

[0082] Where F1 is the output tension value of the motor corresponding to propeller 1, F2 is the output tension value of the motor corresponding to propeller 2, F3 is the output tension value of the motor corresponding to propeller 3, and F4 is the output tension value of the motor corresponding to propeller 4; d Enter the thrust value for the system base; θ and φ are Euler angles, is the yaw angle of the x-axis, θ is the roll angle of the y-axis, φ is the pitch angle of the z-axis, and θ pwm ,φ pwm , Represents the analog signals of yaw angle, roll angle and pitch angle in the control system; k1, k2, k3 and k4 are the thrust control constants corresponding to the propeller, and the control constant range is between 0 and 1000; pwm baseis the basic value of the analog signal, and the basic value is 1000; therefore, in the control system, by controlling the k values ​​corresponding to the four propellers, the output thrust of the four propellers can be controlled; for example, the maximum speed of the selected motor is 10000 rpm, and the drone is set to gradually increase from 0 to 5000 rpm when it starts. At this time, k1, k2, k3, and k4 are all adjusted to 500, and the power of the four motors is 50%, achieving a hovering state; during normal flight, the values ​​of k2 and k4 are 700, and k1 and k3 remain unchanged, and the drone moves forward. Move forward; when obstacle avoidance is required, the k value is set to 850 and the motor output power is 85%. If obstacle avoidance is required on the α side, increase the k2 and k3 values ​​to 850, increase the propeller output thrust, adjust the k1 and k4 values ​​to 500, reduce the propeller output thrust on this side, and move the drone to the β side; the highest k value of the drone is set to 950, and the motor output power is 95%, at which time the maximum power is obtained; after reaching the target location, k1, k2, k3, and k4 are all adjusted to 500 to achieve a hovering state, and then gradually decrease to 0, and the drone lands.

[0083] Specifically, the force and torque generated by the propeller rotation and the propeller speed satisfy the following relationship:

[0084]

[0085] Where f is the total thrust generated by the four propellers, τ x , τ y , τ z The propellers are

[0086] The torque generated on the x, y, and z axes; c T is the propeller thrust coefficient; c M is the propeller torque coefficient; d is the distance from the fuselage to any motor, and the distances from the motors to the fuselage are equal at all four locations; They are the angular velocities corresponding to propeller 1, propeller 2, propeller 3, and propeller 4 respectively.

[0087] The position and attitude of the drone during flight change. Specifically, the position and attitude of the drone are controlled by the drone position and attitude dynamics model. Among them, the rotation order of the drone is defined: first around the z-axis of the body, then around the y-axis of the body, and finally around the x-axis of the body. Specifically, the drone position and attitude dynamics model is as follows:

[0088]

[0089]

[0090] in, is the total rotation matrix of the drone; R(φ) is the sub-rotation matrix for rotating φ around axis x; R(θ) is the sub-rotation matrix for rotating θ around axis y; Rotation around axis z The sub-rotation matrix of .

Claims

1. A deformable drone, characterized in that: It comprises a machine body (3) and four rotor mechanisms (1) fixed on the machine body (3), wherein one end of each rotor mechanism (1) is hinged to the machine body (3) and the other end is provided with a propeller mechanism (2); The machine body (3) is provided with a slider limiting mechanism (4) for driving the four rotor mechanisms (1) to rotate synchronously, and the slider limiting mechanism (4) is used to drive the four rotor mechanisms (1) to be retracted synchronously inwards.

2. The deformable UAV and control method thereof according to claim 1, characterized in that: The rotor mechanism (1) comprises two upper connecting rods (11), two lower connecting rods (12) and a linkage rod (13); the two upper connecting rods (11) are fixedly connected to form an upper support arm; the two lower connecting rods (12) are fixedly connected to form a lower support arm; one end of the upper support arm and the lower support arm are connected via a motor cabin support frame (14); the motor cabin support frame (14) is used to install a propeller mechanism (2); the other end of the upper support arm is hinged to the body (3) via a fourth pin shaft (10); the other end of the lower support arm is hinged to the body (3) via a second pin shaft (18); one end of the linkage rod (13) is hinged to the lower support arm via a first pin shaft (17); the other end is hinged to a slider limiting mechanism (4) via a third pin shaft (19).

3. The deformable drone according to claim 1, characterized in that: The two upper connecting rods (11) are fixedly connected via two first reinforcing connecting plates (15), and the two lower connecting rods (12) are fixedly connected via two second reinforcing connecting plates (6).

4. The deformable drone according to claim 1, characterized in that: The propeller mechanism (2) comprises a motor (23), a propeller (21) and a barrel-shaped motor cabin (22); the propeller (21) is fixed to the output end of the motor (23); the motor (23) is fixed in the motor cabin (22); and the motor cabin (22) is fixedly connected to the rotor mechanism (1) via two first bolts (24) and two second bolts (25).

5. The deformable drone according to claim 1, characterized in that: The body (3) comprises an upper top plate (31) and a bottom support plate (33); the upper top plate (31) and the bottom support plate (33) are fixedly connected via four positioning columns (32); eight structural pillars (35) are also arranged between the upper top plate (31) and the bottom support plate (33); every two of the structural pillars (35) are used to rotatably connect the rotor mechanism (1); the structural pillars (35) are hinged to the rotor mechanism (1); and two frame legs (36) are fixed to the bottom of the bottom support plate (33).

6. The deformable drone according to claim 5, characterized in that: The bottoms of the structural pillars (35) are fixed with intermediate partitions (34), and the intermediate partitions (34) are used to limit the slider limiting mechanism (4).

7. The deformable drone according to claim 1, characterized in that: The slider limiting mechanism (4) comprises a cross-shaped central slider (41) and a slider electric cylinder (42) for driving the central slider (41) to move vertically, the four side ends of the central slider (41) are hinged to the rotor mechanism (1), the four side ends of the central slider (41) are provided with guide holes, the bottom of the slider electric cylinder (42) is fixed on the machine body (1), and the telescopic end of the slider electric cylinder (42) is fixedly connected to the central slider (41).

8. The deformable drone according to claim 1, characterized in that: The invention also comprises a control system (5), wherein the control system (5) comprises a power module, a flight control module, a GPS module, a three-dimensional depth recognition camera (51), an unmanned aerial vehicle dynamics module and a motor drive module, wherein the power module is electrically connected to the flight control module, the GPS module, the three-dimensional depth recognition camera (51), the unmanned aerial vehicle dynamics module and the motor drive module are all electrically connected to the flight control module, and the three-dimensional depth recognition camera (51) is arranged at the bottom of the body (1).

9. A control method for a deformable drone according to any one of claims 1 to 8, characterized in that: The steps include: S1: Before the flight mission begins, set the initial position of the drone and the initial position of the destination in the flight control module, and use the flight control module to set the flight path and flight altitude; the initial position includes longitude and latitude, the upper and lower limits of the flight altitude during the flight process, the upper limit of the flight speed, and the longitude, latitude and altitude of the destination; S2: After the flight mission begins, the motor (23) starts working, the drone rises to the set flight altitude, and then flies above the destination coordinates; during the flight, the three-dimensional depth recognition camera (25) identifies the front of the drone, and the flight control module controls whether the drone automatically avoids obstacles and bypasses; S3: After arriving at the destination coordinates, the drone performs coordinate calibration. After confirming that its own position coordinates are consistent with the set destination coordinates, it hovers at the set target height to perform the flight mission; S4: After the drone completes the mission at the destination, it returns to the destination. S41: swapping the coordinates of the initial position of the drone and the initial position of the destination set in step S1, and starting the return mission, the process is the same as step S2; S42: After returning to the initial position coordinates of the UAV, the slider electric cylinder (42) starts to work, so that the UAV is in an unfolded posture; S43: The three-dimensional depth recognition camera (51) identifies whether there are obstacles during the landing process. If no obstacles are identified below the drone, the drone will land slowly at the lowest speed; if no obstacles are identified below the drone, the landing position coordinates will be changed to avoid obstacles; S44: After landing, the motor (23) stops working, the slider electric cylinder (42) returns to the initial state, and the four-way rotor mechanism (1) returns to the initial state; S5: Repeat steps S1-S4 to complete the next flight mission.

10. The control method of a deformable UAV according to claim 7, characterized in that: In step S2, the drone uses the three-dimensional depth recognition camera (51) in conjunction with the flight control module to achieve obstacle avoidance and detour as follows: S21: Establish a three-dimensional spatial coordinate system using the center of mass of the deformable drone as the coordinate origin; S22: The three-dimensional depth recognition camera (51) collects images in front of the drone frame by frame, and the flight control module determines obstacles in the collected images; S23: The flight control module selects normal flight or proceeds to the next step according to the proportion of obstacles in the left and right anchor frames; S24: The flight control module selects the hovering mode or automatic obstacle avoidance and detour according to the ratio of the obstacles on the left and right sides to the area of ​​the anchor frame. If automatic obstacle avoidance and detour is selected, the next step is performed. S25: The flight control module adjusts the thrust control constants of several propellers according to the proportion of the left and right anchor frames to achieve obstacle avoidance and detour.

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