A Structure and Control Method of a Linear Multi-Rotor Plant Protection UAV Based on Tilt-Rotor

Abstract

The present invention discloses a structure and control method of a linear multi-rotor plant protection unmanned aerial vehicle based on a tilt-rotor, including a main lift power structure, a tilt power structure, and a main body frame structure; the main body frame structure is located in the middle section; the main lift power structures are distributed at the left and right ends of the main body frame structure, and the tilt power structures are symmetrically distributed between the main body frame structure and the main lift power structures; the vector power structure of the present invention has flexible attitude changes, can ensure that the unmanned aerial vehicle operates more smoothly and accurately, improves the operation efficiency, and at the same time adapts to the complex operation environment with diverse terrains in China.

Description

Technical Field

[0001] The present invention relates to the fields of unmanned aerial vehicle control and agricultural plant protection, and is a linear multi-rotor plant protection unmanned aerial vehicle and control method for adjusting the attitude by tilting the rotor. Background Art

[0002] In recent years, numerous technological changes in the agricultural field have promoted the transformation of China from a large agricultural country to a powerful agricultural country. The proposal of intensive agriculture and precision agriculture requires integrating technology into agriculture. In the field of agricultural plant protection, the emergence of plant protection unmanned aerial vehicles indicates that it has been widely recognized that plant protection unmanned aerial vehicles replace traditional sprayers for field plant protection operations. Plant protection unmanned aerial vehicles not only have higher operation efficiency but also have better spraying effects than manual spraying. However, at present, there are still many problems in the actual application of plant protection unmanned aerial vehicles.

[0003] At present, plant protection unmanned aerial vehicles mainly include quad-rotor unmanned aerial vehicles, fixed-wing unmanned aerial vehicles, helicopters, etc. Multi-rotor unmanned aerial vehicles are driven by motors. Although the cost is low, due to their small size, poor load-carrying capacity, narrow operation spray width, and obvious interference between rotors, the operation efficiency is poor and they cannot meet the requirements of high-efficiency and precision operations. Fixed-wing plant protection unmanned aerial vehicles fly at a high altitude and have a long endurance time, but the downward pressure wind field is small, the droplet penetration is poor, and the adhesion rate is low. At the same time, fixed-wing requires a professionally trained pilot, and individual growers generally cannot use it. Plant protection helicopters are driven by fuel, which can, to a certain extent, make up for the deficiencies of the former two, but their cost is high, the later maintenance price is high, the overall quality requirements for pilots are higher, and the economic pressure on farmers is greater. The linear multi-rotor plant protection aircraft proposed in Patent CN202023305357.0 effectively expands the operation spray width through a linear structure and reduces the rotor interference effect, but the control is difficult, and multiple attitude adjustment motors are required to maintain the attitude stability of the aircraft, and the energy utilization rate is poor. Summary of the Invention

[0004] Aiming at the above problems, the present invention proposes a linear tilt-wing plant protection unmanned aerial vehicle and control method, which effectively combines the advantages of a wide operation spray width of a linear aircraft and high energy utilization rate of a fixed wing by using a tilting structure, meeting the needs of modern agriculture. The linear mechanical structure directly increases the operation spray area of the unmanned aerial vehicle. At the same time, the "one"-shaped rotor layout effectively reduces interference, makes the downward pressure wind field of the rotor uniform and sufficient for operation, and reduces the waste of pesticides caused by repeated operations. The energy utilization rate of the motors of the tilt-wing structure is high, and the attitude change is flexible, which can ensure that the operation of the unmanned aerial vehicle is smoother and more accurate.

[0005] The present invention discloses a linear multi-rotor plant protection unmanned aerial vehicle based on tilting rotors. This plant protection unmanned aerial vehicle is mainly aimed at the scattered planting plots in China. In large-area continuous operation scenarios, the one-time operation spray width is large and the operation efficiency is high.

[0006] The technical solution of the present invention includes: a structure of a linear multi-rotor plant protection UAV based on a tilt-rotor, which includes a main lift power structure, a tilt power structure, and a main body frame structure; the main body frame structure is located in the middle section; the main lift power structures are distributed at the left and right ends of the main body frame structure, and the tilt power structures are symmetrically distributed between the main body frame mechanism and the main lift power structures;

[0007] The main lift power structure includes a main lift blade 1, a main lift motor 2, a main lift motor fixing plate 3, a main lift electronic speed controller 4, a first pipe clamp, a centrifugal nozzle 6, a sub-control fixing plate 7, a main lift sub-control circuit board 8, and a main rod 9; the main lift blade 1 is fixed to the main lift motor 2 by screws, the main lift motor 2 is fixed to the main lift motor fixing plate 3 by screws, and then clamped by the first pipe clamp and fixed to the main rod 9 together with the centrifugal nozzle 6 at the lower end; the main lift electronic speed controller 4 and the main lift sub-control board 8 are respectively fixed on two sub-control fixing plates 7 and fixed to the main rod 9 by the first pipe clamp. The main lift sub-control board 8 receives commands from the control board 26, gives signals to the main lift electronic speed controller 4, drives the main lift motor 2 to rotate, and the centrifugal nozzle 6 integrates a motor electronic speed controller inside and can be directly driven to adjust the speed by receiving the PWM signal of the main lift sub-control circuit board 8;

[0008] The tilt power structure includes a tilt carbon plate 10, a tilt sub-control circuit board 11, a servo fixing aluminum part 12, a servo 13, a tilt electronic speed controller 14, a clamping aluminum part 15, a second pipe clamp, a tilt motor fixing plate 17, a bearing fixing aluminum part 18, a tilt carbon tube 19, a bearing 20, a tilt motor 21, and a tilt blade 22; the upper part of the tilt carbon plate 10 is fixed with the tilt sub-control board 11 and the tilt electronic speed controller 14 by screws; the upper parts of the two tilt carbon plates 10 are fixed to the main rod 9 by the first pipe clamp; a tilt carbon tube 19 is provided at the middle part of the lower end of the tilt carbon plate 10, and both ends of the tilt carbon tube 19 are fixed by two bearings 20 and two second pipe clamps. The bearing fixing aluminum part 18 is used to fix the bearing 20. The two clamping aluminum parts 15 jointly hoop the tilt carbon tube 19 on the one hand, and on the other hand, there is a perforation on the tilt carbon tube 19 to make the fixing positions of the clamping aluminum parts 15 relatively consistent; a servo fixing aluminum part 12 is provided at a position close to one end of the tilt carbon tube 19, the servo fixing aluminum part 12 fixes the servo 13, and the output shaft of the servo 13 is nested in the groove of the clamping aluminum part 15 to drive the entire tilt carbon tube 19 to rotate; the tilt blade 22 is fixed to the tilt motor 21 by a nut; the installation hole of the tilt motor 21 on the tilt motor fixing plate 17 can be connected to two second pipe clamps and fixed to the tilt carbon tube 19;

[0009] The main frame structure includes a spirit level 23, an inertial navigation module 24, shock pads 25, a control board 26, a GPS antenna 27, a programmer 28, a remote control receiver 29, a tee 30, a small battery 31, a small battery fixing plate 32, a water pump fixing plate 33, a water pump 34, an on-board battery 35, a battery fixing plate 36, a cross bar 37, a pin board 38, a water tank fixing plate 39, a leg carbon tube 40, a water tank 41, a water level gauge 42, a landing carbon tube 43, and a fixed carbon plate 44; the inertial navigation module 24, the programmer 28, the remote control receiver 29, and the water level gauge 42 are connected to the control board 26 through the interfaces on the control board 26 and transmit data to the control board 26. The small battery 31 supplies power to the control board 26 and the above sensors through the battery interface on the control board 26; the spirit level 23, the shock pads 25, the control board 26, the GPS antenna 27, the programmer 28, and the receiver 29 are rigidly connected to the fixed carbon plate 44 through screws; the two leg carbon tubes 40 are connected and fixed to the main rod 9 through the tee 30; the two fixed carbon plates 44 are fixed to the main rod 9 through four first pipe clamps, screws, and nuts; the water pump fixing plate 33 is fixed to the leg carbon tube 40 through two first pipe clamps, and there are positioning and mounting holes for the water pump 34 on it, facilitating the fixing of the water pump 34; the small battery 31 is bound to the small battery fixing plate 32 through a battery tie, enabling quick replacement; the small battery fixing plate 32 is fixed to the main rod 9 through two first pipe clamps; the pin board 38 and the water tank fixing plate 39 have the same pipe clamp positioning holes and are fixed to the cross bar 37 through four first pipe clamps, and the cross bar 37 is connected to the leg carbon tube 40 through the tee 30; the on-board battery 35 is the main power supply module of the drone and is fixed to the battery fixing plate 36 through a battery tie, and the battery fixing plate 36 is connected to the pin board 38 through a chute; there are positioning and mounting holes for the water tank 41 on the water tank fixing plate 39, facilitating the fixing of the water tank; the water level gauge 42 is located at the bottom of the water tank 41 and measures the water level height of the water tank based on the ultrasonic principle; the two leg carbon tubes 40 are fixedly connected to the landing carbon tube 43 through two tees 30 respectively, for the landing buffer of the drone.

[0010] Further, the clamping aluminum part 15 adopts a structure with a long steering arm, which can effectively reduce the gear wear of the high-frequency rotation of the servo 13. At the same time, there is enough space with a sufficient margin on the tilting carbon plate 10, facilitating the 360-degree rotation of the clamping aluminum part 15 connected to the servo 13.

[0011] Further, the inertial navigation module 24 is adhered to the shock pad 25 through three layers of shock-absorbing materials; the spirit level 23 is used to calibrate the zero bias of the initial angle of the drone; the GPS antenna 27 is used for the inertial navigation module 24 to receive GNSS data; the programmer 28 is used for the software test of the drone; the receiver 29 is responsible for receiving the remote control instructions and transmitting the data to the control board 26.

[0012] Further, the pin board 38 has a chute structure and positioning holes for pulling the pin, facilitating the quick replacement of the battery.

[0013] A structural control method for a linear multi-rotor plant protection UAV based on a tilt-rotor, comprising the following steps:

[0014] Step 1, respectively establish the dynamic models of the three-axis rotation and translation of the UAV;

[0015] Step 2, initialize the main control chip and the external sensors;

[0016] Step 3, perform self-check on the UAV sensors. If the self-check is abnormal, display an alarm through the external expansion light strip and repeat Step 3. If it is normal, proceed to Step 4;

[0017] Step 4, wait for the operator to unlock through human-computer interaction, and the UAV switches from the self-locking state to the waiting-to-take-off state;

[0018] Step 5, receive human-computer interaction data, and the UAV performs task switching. The tasks are specifically the attitude mode, the altitude-keeping mode, the point-positioning mode, and the one-key landing mode. When the GPS signal is weak or lost, it will be forced to switch from the point-positioning mode to the altitude-keeping mode. In the attitude mode, the UAV will read and control the information related to the attitude angle and angular velocity; in the altitude-keeping mode, the UAV will read and control the attitude angle, angular velocity, speed, and flight altitude information; in the point-positioning mode, the UAV will read and control the attitude angle, angular velocity, speed, and position information and support the functions of trajectory planning and tracking; in the one-key landing mode, the UAV will end the current task and slowly descend in place; according to the dynamic model of the tilt-rotor plant protection UAV established in Step 1, adopt a composite control method combining PID and active disturbance rejection controller, and combining cascade control and parallel control; to address the problem that control signals are prone to loss caused by the ultra-long fuselage, adopt a master-slave control strategy based on CAN communication for the main control and sub-control;

[0019] Step 6, after the UAV lands safely, the system control is turned off, and return to Step 4.

[0020] The main lifting blade 1 of the present invention is a 32-inch carbon fiber composite blade, which is responsible for providing a continuous and stable downward wind field and lift. The main lifting motor 2 is horizontally fixed to provide power to the main lifting blade 1. In view of the easy generation of coupling during the rotation of different motors, the main lifting motors 2 are set to have the same rotational speed and opposite rotational directions to eliminate coupling. The tilting blade 22 of the present invention is a 22-inch carbon fiber composite blade, which is responsible for providing the lift for pitch and yaw changes. The tilting motor 21 is fixed to the tilting motor fixing plate 17 by screws and nuts, and is fixed to the tilting carbon tube 19 by a 25-mm pipe clamp 16 to ensure that the motor and the servo rotate coaxially. By controlling the servo to drive the motor to change the rotational direction, the changes in the pitch angle and the yaw angle are completed, increasing the flexibility and endurance of the whole machine. A tripod carbon tube 40 is provided in the middle of the fuselage to provide stable takeoff and landing points. The on-board battery 35 is stored at the upper end of the battery fixing plate 36 extending from the transverse carbon rod of the frame, and the operation medicine box 41 is fixed at the lower end of the plane to ensure that the center of gravity of the whole machine is located below the middle of the main rod, which is beneficial to balance control.

[0021] Considering that the straight-line tilting multi-rotor plant protection UAV uses a 3-meter-long carbon tube main rod 9 as the main load-bearing and moving platform, and the layout of the signal lines is relatively long and vulnerable to interference, the present invention adopts an interactive control of master-sending and slave-controlling based on CAN bus communication. The control board 26 is the main control board for perception, operation and control, and the tilting sub-control circuit board 11 receives the instructions from the main control board through the CAN bus and directly controls the motors and servos to perform corresponding actions.

[0022] The control method of the present invention uses a composite control method combining PID and active disturbance rejection controller, and combining cascade control and parallel control. The tilting-wing plant protection UAV can directly obtain the corresponding force in the X-axis direction by adjusting the tilting rotor, instead of only being able to achieve it by adjusting the corresponding attitude angle like an ordinary multi-rotor UAV. The specific control method is to divide the attitude control and position control of the tilting-wing plant protection UAV into two independent control systems. Each control structure is a cascade feedback control, and then the two control results are added together to form a parallel control. The attitude control is composed of a cascade of an angle controller, an angular velocity controller, and an angular acceleration controller. The angle data and the angular velocity data are estimated by a combined navigation algorithm, and the angular acceleration is estimated by a differential tracker in the active disturbance rejection control algorithm. The position control is similar to the attitude control, and is composed of a cascade of a position controller, a speed controller, and an acceleration controller. The position information and the speed information are estimated by a combined navigation algorithm, and the acceleration information is estimated by a differential tracker.

[0023] The present invention is mainly applied to liquid medicine spraying and granular sowing in the process of plant protection operations. It can meet multi-directional autonomous operations for various diverse and complex terrains such as plains, mountains, and hills. Different from the multi-rotor plant protection unmanned aerial vehicles (UAVs) currently on the market, the present invention adopts a linear flight structure different from traditional UAVs. Two main lift motors 2 and two tilt motors 21 are evenly distributed, ensuring the uniform distribution of the downward wash airfield, reducing the interference flow between the rotors, making the droplets more uniformly attached to the crop canopy while generating penetration force. Different operation methods can be adopted for different operation sites. For small plots or rugged terrains, single-machine operation is adopted, manually controlled by an operator, and a medicine box and battery matching the plot are carried to directly complete the plant protection task, reflecting the flexibility and operability of the plant protection operation. For large plots, the length of the main rod can be adjusted according to the operation requirements, and the spraying width can be flexibly increased according to the site specifications to improve the operation efficiency.

[0024] Compared with traditional plant protection UAVs, the innovative points of the present invention are as follows:

[0025] (1) "One"-shaped power distribution, main lift power structure, tilt power structure, and main body frame structure; the main body frame structure is located in the middle section; the main lift power structure is distributed at the left and right ends of the main body frame structure, and the tilt power structure is symmetrically distributed between the main body frame mechanism and the main lift power structure; the interference flow between the rotors is reduced, the spraying width is widened, the downward pressure airfield of the rotors is evenly and fully operated, the waste of pesticides caused by repeated operations is reduced, and the operation effect is good.

[0026] (2) Vector-type power structure, with flexible attitude changes, which can ensure smoother and more accurate operations of the UAV, improve the operation efficiency, and at the same time adapt to the complex operation environment with diverse terrains in China.

[0027] (3) Master-slave interactive control, which can not only ensure that long-distance communication is not easily interfered, but also reduce the system risk through real-time monitoring and inspection algorithms. Description of the Drawings

[0028] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0029] Figure 2 is a schematic diagram of the connecting component between the main lift rotor and the spray rod of the present invention;

[0030] Figure 3 is a schematic diagram of the tilt power structure of the present invention; (a) is a schematic diagram of one-sided tilt power structure; (b) is a schematic diagram of the other-sided tilt power structure;

[0031] Figure 4 is a schematic diagram of the specific structure of the upper part of the main body frame structure of the present invention;

[0032] Figure 5 is a schematic diagram of the main body frame structure of the present invention;

[0033] Figure 6 Schematic diagram of the interactive control of the master-slave control of the present invention;

[0034] Figure 7 Dimension marking diagram of the dynamic model of the present invention;

[0035] Figure 8 Block diagram of the control system of the present invention;

[0036] Figure 9 Control flow chart of the present invention;

[0037] Figure 2 In it, 1 - main lifting blade, 2 - main lifting motor, 3 - main lifting motor fixing plate, 4 - main lifting electronic speed controller, 5 - 40mm pipe clamp, 6 - centrifugal nozzle, 7 - slave control fixing plate, 8 - main lifting slave control board, 9 - main rod.

[0038] Figure 3 In it, 10 - tilting carbon plate, 11 - tilting slave control board, 12 - servo fixing aluminum part, 13 - servo, 14 - tilting electronic speed controller, 15 - clamping aluminum part, 16 - 25mm pipe clamp, 17 - tilting motor fixing plate, 18 - bearing fixing aluminum part, 19 - tilting carbon tube, 20 - bearing, 21 - tilting motor, 22 - tilting blade.

[0039] Figure 4 In it, 23 - level gauge, 24 - inertial navigation module, 25 - shock pad, 26 - control board, 27 - GPS antenna, 28 - programmer, 29 - receiver.

[0040] Figure 5 In it, 30 - tee, 31 - small battery, 32 - small battery fixing plate, 33 - water pump fixing plate, 34 - water pump, 35 - airborne battery, 36 - battery fixing plate, 37 - cross bar, 38 - pin board, 39 - water tank fixing plate, 40 - leg carbon tube, 41 - water tank, 42 - water level gauge, 43 - landing carbon tube, 44 - fixing carbon plate. Detailed implementation manner

[0041] A structure of a linear multi-rotor plant protection UAV based on a tilt-rotor includes a main lift power structure, a tilt power structure, and a main body frame structure; the main lift power structure includes a main lift blade 1, a main lift motor 2, a main lift motor fixing plate 3, a main lift electronic speed controller 4, a 40mm pipe clamp 5 (the first pipe clamp), a centrifugal nozzle 6, a sub-control fixing plate 7, a main lift sub-control circuit board 8, and a carbon fiber main rod 9; the main lift blade 1 is preferably a 32-inch blade and is fixed to the main lift motor 2 by screws. The main lift motor 2 is fixed to the main lift motor fixing plate 3 by screws and then clamped by the 40mm pipe clamp 5 and fixed to the main rod 9 together with the centrifugal nozzle 6. The main lift motor fixing plate 3 is compatible with most motor mounting holes on the market and has a certain universality. The centrifugal nozzle 6 can be applied to multiple varieties of pesticides, with adjustable atomization, quick replacement, and effectively improving the plant protection efficiency of the present invention. The main lift electronic speed controller 4 and the main lift sub-control board 8 are respectively fixed on two sub-control fixing plates 7 and fixed to the main rod 9 by the 40mm pipe clamp 5 to ensure that the rotation of the main lift blade 1 will not be interfered. A single main lift sub-control board 8 can control 1 main lift motor 2 and 1 centrifugal nozzle 6. The main lift sub-control board 8 receives commands from the control board 26, gives signals to the main lift electronic speed controller 4, and drives the main lift motor 2 to rotate. The centrifugal nozzle 6 integrates a motor electronic speed controller inside and can be directly driven and speed-regulated by receiving the PWM signal of the main lift sub-control board 8.

[0042] The tilt power structure includes a tilt carbon plate 10, a tilt sub-control circuit board 11, a servo fixing aluminum part 12, a servo 13, a tilt electronic speed controller 14, a clamping aluminum part 15, a 25mm pipe clamp 16, a tilt motor fixing plate 17, a bearing fixing aluminum part 18, a tilt carbon tube 19, a bearing 20, a tilt motor 21, and a tilt blade 22; the tilt carbon plate 10 is fixed with the tilt sub-control board 11 and the tilt electronic speed controller 14 by screws; two tilt carbon plates 10 are fixed to the main rod 9 by the 40mm pipe clamp 5; the tilt carbon tube 19 is fixed between two tilt carbon plates through two bearings 20 and two 25mm pipe clamps (the second pipe clamp); the bearing is a standard bearing with an inner diameter of 25 mm and an outer diameter of 37 mm, facilitating the rotation of the servo 13; two clamping aluminum parts 15 on the one hand jointly hoop the tilt carbon tube 19, and on the other hand, there is a perforation on the tilt carbon tube 19 to make the fixing positions of the clamping aluminum parts 15 relatively consistent; the output shaft of the servo 13 is nested in the groove of the clamping aluminum part 15 to drive the entire tilt carbon tube 19 to rotate; the clamping aluminum part 15 adopts a long servo arm structure, which can effectively reduce the gear wear of the high-frequency rotation of the servo 13. At the same time, there is enough margin space on the tilt carbon plate 10 to facilitate the 360-degree rotation of the clamping aluminum part 15 connected to the servo 13; the tilt blade 22 is fixed to the tilt motor 21 by a nut; the installation holes of the tilt motor 21 on the tilt motor fixing plate 17 can be connected to two 25mm pipe clamps 16 and fixed to the tilt carbon tube 19.

[0043] The main frame structure includes a spirit level 23, an inertial navigation module 24, shock pads 25, a control board 26, a GPS antenna 27, a programmer 28, a remote control receiver 29, a tee joint 30, a small battery 31, a small battery fixing plate 32, a water pump fixing plate 33, a water pump 34, an on-board battery 35, a battery fixing plate 36, a cross bar 37, a pin board 38, a water tank fixing plate 39, a leg carbon tube 40, a water tank 41, a water level gauge 42, a landing carbon tube 43, and a fixed carbon plate 44. The spirit level 23, shock pads 25, control board 26, GPS antenna 27, programmer 28, and receiver 29 are rigidly connected together through screws and the fixed carbon plate 44. The inertial navigation module 24 is adhered to the shock pad 25 through three layers of shock-absorbing materials; the spirit level 23 is used to zero-bias calibrate the initial angle of the drone; the GPS antenna 27 is used for the inertial navigation module 24 to receive GNSS data; the programmer 28 is used for software testing of the drone; the receiver 29 is responsible for receiving remote control instructions and transmitting data to the control board 26. The two leg carbon tubes 40 are connected and fixed to the main rod 9 through the tee joint 30; the two fixed carbon plates 44 are fixed to the main rod 9 through four 40mm pipe clamps 5 and screws and nuts; the water pump fixing plate 33 is fixed to the leg carbon tube 40 through two 40mm pipe clamps 5, and it has positioning and mounting holes for the water pump 34 to facilitate the fixing of the water pump 34; the small battery 31 is bound to the small battery fixing plate 32 through a battery tie, enabling quick replacement; the small battery fixing plate 32 is fixed to the main rod 9 through two 40mm pipe clamps 5; the pin board 38 and the water tank fixing plate 39 have the same pipe clamp positioning holes and are fixed to the cross bar 37 through four 40mm pipe clamps 5, and the cross bar 37 is connected to the leg carbon tube 40 through the tee joint 30; the pin board 38 has a chute structure and positioning holes for pulling the pin, facilitating quick replacement of the battery; the on-board battery 35 is the main power supply module of the drone and is fixed to the battery fixing plate 36 through a battery tie, and the battery fixing plate 36 is connected to the pin board 38 through a chute; the water tank fixing plate 39 has positioning and mounting holes for the water tank 41 to facilitate the fixing of the water tank; the water level gauge 42 is located at the bottom of the water tank 41 and measures the water level height of the water tank based on the ultrasonic principle; the two leg carbon tubes 40 are respectively fixedly connected to the landing carbon tube 43 through two tee joints 30 for the landing buffer of the drone.

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

[0045] Figure 1 The following shows the overall structure schematic diagram of the present invention. The present invention uses a 3-meter-long carbon fiber tube with a diameter of 40 mm as the main body, symmetrically equipped with 2 tilting structures perpendicular to the fuselage and facing downwards, which improves the wind field utilization efficiency of the tilting propellers 22.

[0046] Figure 2The following is a schematic diagram of the main lifting power structure of the present invention. The main lifting propeller 1 is preferably a 32-inch propeller and is the main source of lift. The main lifting motor 2 is fixed to the main lifting motor fixing plate 3 by screws and then clamped by a 40mm pipe clamp 5, and is fixed to the main rod 9 together with the centrifugal nozzle 6. The main lifting motor fixing plate 3 is compatible with most of the motor mounting holes on the market and has a certain universality. The centrifugal nozzle 6 can be applied to multiple varieties of pesticides, with adjustable atomization, quick replacement, and effectively improving the plant protection efficiency of the present invention. The main lifting electronic speed controller 4 and the main lifting sub-control board 8 are respectively fixed on two sub-control fixing plates 7 and fixed to the main rod 9 by a 40mm pipe clamp 5 to ensure that the rotation of the main lifting propeller 1 will not be interfered. A single main lifting sub-control board 8 can control 1 main lifting motor 2 and 1 centrifugal nozzle 6. The main lifting sub-control board 8 receives commands from the control board 26, gives signals to the main lifting electronic speed controller 4, and drives the main lifting motor 2 to rotate. The centrifugal nozzle 6 integrates a motor electronic speed controller inside and can be directly driven and speed-regulated by receiving the PWM signal of the main lifting sub-control board 8.

[0047] Figure 3 The following is a schematic diagram of the tilting power structure of the present invention. The tilting carbon plate 10 of the present invention is fixed with a tilting sub-control board 11 and a tilting electronic speed controller 14 by screws; two tilting carbon plates 10 are fixed to the main rod 9 by a 40mm pipe clamp 5; the tilting carbon tube 19 is fixed between two tilting carbon plates by two bearings 20 and two 25mm pipe clamps; the bearings adopt standard bearings with an inner diameter of 25 mm and an outer diameter of 37 mm to facilitate the rotation of the steering gear 13; on the one hand, two clamping aluminum parts 15 jointly hoop the tilting carbon tube 19, and on the other hand, there is a perforation on the tilting carbon tube 19 to make the fixing positions of the clamping aluminum parts 15 relatively consistent; the output shaft of the steering gear 13 is nested in the groove of the clamping aluminum part 15 to drive the entire tilting carbon tube 19 to rotate; the clamping aluminum part 15 adopts a structure with a long steering arm, which can effectively reduce the gear wear of the high-frequency rotation of the steering gear 13. At the same time, there is enough margin space on the tilting carbon plate 10 to facilitate the 360-degree rotation of the clamping aluminum part 15 connected to the steering gear 13; the tilting motor 21 is fixed with a tilting propeller 22 by a nut; the installation hole of the tilting motor 21 on the tilting motor fixing plate 17 can be connected to two 25mm pipe clamps 16 and fixed to the tilting carbon tube 19.

[0048] Figure 4 The following is a schematic diagram of the specific structure of the upper part of the main body frame of the present invention, showing the main control and test modules of the present invention. The level 23, the shock pad 25, the control board 26, the GPS antenna 27, the burner 28, and the receiver 29 are all hard-connected to the fixed carbon plate 44. The inertial navigation module 24 is adhered to the shock pad 25 through three layers of shock-absorbing materials; the level 23 is used to perform zero-bias calibration on the initial angle of the unmanned aerial vehicle; the GPS antenna 27 is used for the inertial navigation module 24 to receive GNSS data; the burner 28 is used for software testing of the unmanned aerial vehicle; the receiver 29 is responsible for receiving remote control commands and transmitting the data to the control board 26.

[0049] Figure 5 This is a schematic diagram of the main frame structure of the present invention. Two tripod carbon tubes 40 are connected and fixed to the main rod 9 through a tee joint 30; two fixed carbon plates 44 are fixed to the main rod 9 by four 40mm pipe clamps 5 and screws and nuts; the water pump fixing plate 33 is fixed to the tripod carbon tube 40 by two 40mm pipe clamps 5, and there are positioning and installation holes for the water pump 34 thereon, which is convenient for fixing the water pump 34; the small battery 31 is bound to the small battery fixing plate 32 by a battery tie, and can be quickly replaced; the small battery fixing plate 32 is fixed to the main rod 9 by two 40mm pipe clamps 5; the pin plate 38 and the water tank fixing plate 39 have the same pipe clamp positioning holes and are fixed to the cross bar 37 by four 40mm pipe clamps 5, and the cross bar 37 is connected to the tripod carbon tube 40 through a tee joint 30; the pin plate 38 has a chute structure and positioning holes for pulling the pin, which is convenient for quickly replacing the battery; the on-board battery 35 is the main power supply module of the unmanned aerial vehicle and is fixed to the battery fixing plate 36 by a battery tie, and the battery fixing plate 36 is connected to the pin plate 38 through a chute; the water tank fixing plate 39 has positioning and installation holes for the water tank 41, which is convenient for fixing the water tank; the water level gauge 42 is located at the bottom of the water tank 41 and measures the water level height of the water tank according to the ultrasonic principle; the two tripod carbon tubes 40 are respectively fixedly connected to the landing carbon tube 43 through two tee joints 30 for the landing buffer of the unmanned aerial vehicle.

[0050] Figure 6 This is a schematic diagram of the interactive control of the master-slave control of the present invention. To address the problem that control signals are prone to loss due to the ultra-long fuselage, the present invention adopts a master-slave control strategy of master control - sub-control based on CAN communication, and designs an algorithm for real-time detection and real-time verification to ensure the stability and reliability of control signals during the flight of the unmanned aerial vehicle. The control board 26 is the main control board for perception, operation, and control, and the tilt sub-control circuit board 11 receives instructions from the main control board through the CAN bus and directly controls the motors and servos to perform corresponding actions. Real-time monitoring and verification are carried out between the two. When the main control board detects the loss of the sub-control board, it will provide an alarm message to the user through the upper-layer embedded system board using human-computer interaction. At the same time, when the sub-control boards 1 and 2 (main lift sub-control board 8) detect the loss of the main control board (control board 26), they will immediately enter the protection mechanism and stop all motor and servo controls to prevent misoperations from harming the safety of personnel's lives.

[0051] Figure 7 This is a dimension marking diagram of the dynamic model of the present invention. The present invention uses Euler angles θ, ψ to describe the attitude of the unmanned aerial vehicle, that is, the angle between the on-board coordinate system and the ground inertial coordinate system. The ground inertial coordinate system adopts the northeast celestial coordinate system. Among them, the center of mass of the tilt-wing plant protection unmanned aerial vehicle is the origin of the on-board coordinate system, the X-axis is perpendicular to the arm and points to the nose, the Y-axis is parallel to the arm and points to the left side of the nose, and the Z-axis is perpendicular to the arm and points upward. Figure 7Among them, the length from the tilting motor to the main rod is L1, the length from the main rod to the center of gravity is L2, the length of the tilting force arm is L3, the length of the main lifting force arm is L4, the thickness of the motor is L5, and the angles by which the left and right steering gears deviate from the vertical position are θ L and θ R (observed along the +Y direction, clockwise rotation is positive), the total mass of the UAV is m, and the acceleration due to gravity is g. The present invention is based on the three-axis torque and the lift F generated by the four rotors is F = [F L2 F L1 F R1 F R2 T to perform a dynamic analysis and obtain a three-axis rotational dynamics model:

[0052]

[0053] Among them, K torque represents the air counter-torque coefficient, which reflects the relationship between the lift generated by the rotation of the rotor and the counter-torque generated by air friction.

[0054] At the same time, a three-axis translational dynamics model of the UAV is established:

[0055]

[0056] Among them, is the rotation matrix for converting the onboard coordinate system to the ground inertial coordinate system.

[0057] Figure 9 is the control flow chart of the present invention. The execution steps of the entire system are as follows:

[0058] Step 1, initialize the main control chip and initialize the external sensors.

[0059] Step 2, self-check the UAV sensors. If the self-check is abnormal, display an alarm through the external expansion light strip and repeat Step 2. If it is normal, proceed to Step 3.

[0060] Step 3, wait for the operator to unlock through human-computer interaction, and the UAV switches from the self-locking state to the waiting-to-take-off state.

[0061] ​Step 4: Receive human-computer interaction data, and the drone switches tasks, specifically including attitude mode, altitude-holding mode, point-positioning mode, and one-key landing mode. When the GPS signal is weak or lost, it will be forced to switch from point-positioning mode to altitude-holding mode. In attitude mode, the drone will read and control information related to attitude angles and angular velocities; in altitude-holding mode, the drone will read and control attitude angles, angular velocities, speeds, and flight altitudes; in point-positioning mode, the drone will read and control attitude angles, angular velocities, speeds, position information, and support waypoint planning and tracking functions; in one-key landing mode, the drone will end the current task and slowly descend in place.

[0062] Figure 8 is the control system block diagram of the present invention. According to Figure 7 the established dynamic model of the tilt-rotor plant protection drone, a composite control method combining PID and active disturbance rejection controller, and combining cascade control and parallel control is adopted. The tilt-rotor plant protection drone can directly obtain the corresponding force in the X-axis direction by adjusting the tilt-rotors, without the need to achieve it by adjusting the corresponding attitude angles like ordinary multi-rotor drones. This control method specifically divides the attitude control and position control of the tilt-rotor plant protection drone into two independent control systems. Each control structure is a cascade feedback control, and then the two control results are added together to form a parallel control. The attitude control is composed of a cascade of an angle controller, an angular velocity controller, and an angular acceleration controller. The angle data and angular velocity data are estimated by a combined navigation algorithm, and the angular acceleration is estimated by a differential tracker in the active disturbance rejection control algorithm. The position control is similar to the attitude control, composed of a cascade of a position controller, a speed controller, and an acceleration controller. The position information and speed information are estimated by a combined navigation algorithm, and the acceleration information is estimated by a differential tracker. To address the problem of easy loss of control signals caused by the ultra-long fuselage, the present invention adopts the above-mentioned master-slave control strategy based on CAN communication.

[0063] Step 5: After the drone lands safely, the system control is turned off, and it returns to Step 3.

Claims

1. A structure of a linear multi-rotor plant protection UAV based on a tilt-rotor, characterized in that, It includes a main lifting power structure, a tilting power structure, and a main body frame structure; the main body frame structure is located in the middle section; the main lifting power structures are distributed at the left and right ends of the main body frame structure, and the tilting power structures are symmetrically distributed between the main body frame structure and the main lifting power structures; The main lifting power structure includes a main lifting propeller (1), a main lifting motor (2), a main lifting motor fixing plate (3), a main lifting electronic speed controller (4), a first pipe clamp, a centrifugal nozzle (6), a sub-control fixing plate (7), a main lifting sub-control board (8), and a main rod (9); the main lifting propeller (1) is fixed to the main lifting motor (2) with screws, the main lifting motor (2) is fixed to the main lifting motor fixing plate (3) with screws, and then clamped by the first pipe clamp and fixed to the main rod (9) together with the centrifugal nozzle (6) at the lower end; the main lifting electronic speed controller (4) and the main lifting sub-control board (8) are respectively fixed to two sub-control fixing plates (7) and fixed to the main rod (9) by the first pipe clamp. The main lifting sub-control board (8) receives commands from the control board (26), gives signals to the main lifting electronic speed controller (4), drives the main lifting motor (2) to rotate, and the centrifugal nozzle (6) integrates a motor electronic speed controller inside and can directly drive the speed regulation by receiving the PWM signal from the main lifting sub-control board (8); The tilting power structure includes a tilting carbon plate (10), a tilting sub-control board (11), a servo motor fixing aluminum part (12), a servo motor (13), a tilting electronic speed controller (14), a clamping aluminum part (15), a second pipe clamp, a tilting motor fixing plate (17), a bearing fixing aluminum part (18), a tilting carbon tube (19), a bearing (20), a tilting motor (21), and a tilting propeller (22); the tilting carbon plate (10) fixes the tilting sub-control board (11) and the tilting electronic speed controller (14) to the upper part with screws; the upper parts of two tilting carbon plates (10) are fixed to the main rod (9) by the first pipe clamp; a tilting carbon tube (19) is provided at the middle part of the lower end of the tilting carbon plate (10), and both ends of the tilting carbon tube (19) are fixed by two bearings (20) and two second pipe clamps. The bearing fixing aluminum part (18) is used to fix the bearing (20). The two clamping aluminum parts (15) jointly clamp the tilting carbon tube (19) on one hand, and on the other hand, there is a perforation on the tilting carbon tube (19) to make the fixing positions of the clamping aluminum parts (15) relatively consistent; a servo motor fixing aluminum part (12) is provided at a position close to one end of the tilting carbon tube (19), the servo motor fixing aluminum part (12) fixes the servo motor (13), and the output shaft of the servo motor (13) is nested in the groove of the clamping aluminum part (15) to drive the entire tilting carbon tube (19) to rotate; the tilting propeller (22) is fixed to the tilting motor (21) with a nut; the mounting holes of the tilting motor (21) on the tilting motor fixing plate (17) can be connected to two second pipe clamps and fixed to the tilting carbon tube (19); The main frame structure includes a spirit level (23), an inertial navigation module (24), a shock pad (25), a control board (26), a GPS antenna (27), a programmer (28), a receiver (29), a tee (30), a small battery (31), a small battery fixing plate (32), a water pump fixing plate (33), a water pump (34), an on-board battery (35), a battery fixing plate (36), a cross bar (37), a pin board (38), a water tank fixing plate (39), a tripod carbon tube (40), a water tank (41), a water level gauge (42), a landing carbon tube (43), and a fixed carbon plate (44); The inertial navigation module (24), the programmer (28), the receiver (29), and the water level gauge (42) are connected to the control board (26) through the interfaces on the control board (26) and transfer data to the control board (26). The small battery (31) supplies power to the control board (26) and the sensors through the battery interface on the control board (26); The spirit level (23), the shock pad (25), the control board (26), the GPS antenna (27), the programmer (28), and the receiver (29) are rigidly connected to the fixed carbon plate (44) through screws; The two tripod carbon tubes (40) are connected and fixed to the main rod (9) through the tee (30); The two fixed carbon plates (44) are fixed to the main rod (9) by four first pipe clamps and screws and nuts; The water pump fixing plate (33) is fixed to the tripod carbon tube (40) by two first pipe clamps, and there are positioning and mounting holes for the water pump (34) on it, which facilitates the fixing of the water pump (34); The small battery (31) is bound to the small battery fixing plate (32) by battery ties and can be quickly replaced; The small battery fixing plate (32) is fixed to the main rod (9) by two first pipe clamps; The pin board (38) and the water tank fixing plate (39) have the same pipe clamp positioning holes and are fixed to the cross bar (37) by four first pipe clamps. The cross bar (37) is connected to the tripod carbon tube (40) through the tee (30); The on-board battery (35) is the main power supply module of the UAV and is fixed to the battery fixing plate (36) by battery ties. The battery fixing plate (36) is connected to the pin board (38) through a chute; There are positioning and mounting holes for the water tank (41) on the water tank fixing plate (39), which facilitates the fixing of the water tank; The water level gauge (42) is located at the bottom of the water tank (41) and measures the water level height of the water tank based on the ultrasonic principle; The two tripod carbon tubes (40) are fixedly connected to the landing carbon tube (43) through two tees (30) respectively, which is used for the landing buffer of the UAV.

2. The structure of a linear multi-rotor plant protection UAV based on a tilt-rotor according to claim 1, wherein The clamping aluminum part (15) adopts the structure of a long steering arm, which can effectively reduce the gear wear of the high-frequency rotation of the servo (13). At the same time, there is enough space with a sufficient margin on the tilting carbon plate (10), which facilitates the 360-degree rotation of the clamping aluminum part (15) connected to the servo (13).

3. The structure of a linear multi-rotor plant protection UAV based on a tilt-rotor, according to claim 1, is characterized in that The inertial navigation module (24) is adhered to the shock pad (25) through three layers of shock-absorbing materials; The spirit level (23) is used to calibrate the zero bias of the initial angle of the UAV; The GPS antenna (27) is used for the inertial navigation module (24) to receive GNSS data; The programmer (28) is used for software testing of the drone; the receiver (29) is responsible for receiving the instructions from the remote controller and transmitting the data to the control board (26).

4. The structure of a linear multi-rotor plant protection UAV based on a tilt-rotor, as claimed in claim 1, wherein The pin board (38) is provided with a chute structure and positioning holes for pulling the pins, which facilitates the quick replacement of the battery.

5. A structural control method for a linear multi-rotor plant protection UAV based on a tilt-rotor, characterized in that It includes the following steps: Step 1, respectively establish the dynamic models of the three-axis rotation and translation of the drone; Step 2, initialize the main control chip and the external sensors; Step 3, self-check the drone sensors. If the self-check is abnormal, the alarm will be displayed through the extended light strip and step 3 will be repeated. If it is normal, go to step 4; Step 4, wait for the human-computer interaction to unlock, and the drone switches from the self-locking state to the waiting-to-take-off state; Step 5, receive the human-computer interaction data, and the drone performs task switching. The tasks are specifically the attitude mode, the altitude-holding mode, the point-positioning mode, and the one-key landing mode. When the GPS signal is weak or lost, it will be forced to switch from the point-positioning mode to the altitude-holding mode; in the attitude mode, the drone will read and control the information related to the attitude angle and angular velocity; in the altitude-holding mode, the drone will read and control the attitude angle, angular velocity, speed, and flight altitude information; in the point-positioning mode, the drone will read and control the attitude angle, angular velocity, speed, and position information and support the function of flight path planning and tracking; in the one-key landing mode, the drone will end the current task and slowly descend in place; according to the dynamic model of the tilt-rotor plant protection drone established in step 1, a composite control method combining PID and active disturbance rejection controller, and combining cascade control and parallel control is adopted; to address the problem that the control signal is prone to loss caused by the ultra-long fuselage, a master-slave control strategy based on CAN communication for the main control-sub-control is adopted; Step 6, after the drone lands safely, the system control is turned off, and return to step 4.

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