Variable pitch structure and control method for single-layer variable pitch coaxial twin propeller unmanned aerial vehicle

Abstract

The application discloses a variable-pitch structure and a control method for a single-layer variable-pitch coaxial double-propeller unmanned aerial vehicle, relates to the technical field of variable-pitch control of coaxial double-propeller unmanned aerial vehicles, and comprises an active single-layer variable-pitch mechanism and a passive single-layer variable-pitch mechanism. When the single-layer variable-pitch coaxial double-propeller unmanned aerial vehicle needs to move horizontally, the active variable-pitch propeller layer is driven by the rotating swash plate mechanism to actively change the pitch, thereby generating a horizontal moment; the passive variable-pitch propeller layer is passively tilted under the action of aerodynamic force to generate a horizontal moment, the fixed propeller hub connection structure of the original passive variable-pitch propeller layer is changed, the passive single-layer variable-pitch mechanism is adopted, a passive variable-pitch propeller hub and a pair of propeller hub movable pins are added, the propeller hub movable pin is arranged at an angle of 45 degrees or 135 degrees with the propeller hub axis, so that the propeller hub movable pin also changes the pitch periodically under the action of aerodynamic force, the reaction moment caused by the gyroscopic effect during high-speed flight is reduced, and the unmanned aerial vehicle has better controllability and flight stability.

Description

Technical Field

[0001] This invention relates to the field of coaxial dual-propeller unmanned aerial vehicle (UAV) variable pitch control technology, and in particular to a variable pitch structure and control method for a single-layer variable pitch coaxial dual-propeller UAV. Background Technology

[0002] The aerodynamic layout of a coaxial twin-rotor UAV is similar to that of a common helicopter. However, unlike helicopters, the coaxial twin-rotor layout eliminates the tail rotor commonly found on helicopters, using two coaxially arranged propellers of the same diameter. Like helicopters, it uses swashplates or vector steering mechanisms to control the aircraft's pitch and roll degrees of freedom.

[0003] Traditional single-layer variable-pitch coaxial dual-propeller drones consist of a variable-pitch blade layer and a constant-pitch blade layer. The variable-pitch blade layer provides active horizontal torque, stabilizes the flight attitude, and generates the horizontal torque required for flight; the constant-pitch blade layer is responsible for balancing the motor's rotational torque and providing vertical lift. Typically, the constant-pitch blade layer in a single-layer variable-pitch coaxial dual-propeller drone uses either a shaftless design or a 90° rotating shaft design.

[0004] When the drone needs to move horizontally, the variable-pitch blade layer actively generates a horizontal torque, while the constant-pitch blade layer passively tilts under the action of the force to generate a horizontal torque. At the same time, due to the action of the gyro torque, a large reaction force is generated, which makes the drone's controllability and flight stability worse. Summary of the Invention

[0005] To address the technical problem of existing single-layer variable-pitch coaxial dual-propeller UAVs where, during horizontal movement, the variable-pitch blade layer actively generates a horizontal torque, while the constant-pitch blade layer passively tilts and generates a horizontal torque under pressure, and simultaneously, the gyroscopic torque generates a large reaction force, thus degrading the UAV's maneuverability and flight stability, this invention provides a variable-pitch structure and control method for a single-layer variable-pitch coaxial dual-propeller UAV. The technical solution adopted is as follows:

[0006] The pitch-changing structure for a single-layer variable-pitch coaxial dual-propeller UAV includes an active single-layer pitch-changing mechanism and a passive single-layer pitch-changing mechanism. The active single-layer pitch-changing mechanism includes a rotary motor connector and a swashplate mechanism. The swashplate mechanism is connected to one output shaft of the coaxial motor of the coaxial dual-propeller UAV via the rotary motor connector. The swashplate mechanism drives the active pitch-changing blade layer of the coaxial dual-propeller UAV to perform active periodic pitch-changing. The passive single-layer pitch-changing mechanism drives the passive pitch-changing blade layer of the coaxial dual-propeller UAV to perform passive periodic pitch-changing under the passive action of aerodynamic force.

[0007] The passive single-layer variable pitch mechanism includes a passive variable pitch rotor hub, a pair of rotor hub movable pins, and a connecting rotor hub. The output shaft on the other side of the coaxial motor of the coaxial dual-propeller UAV is connected and installed to one side of the passive variable pitch rotor hub, driving the passive variable pitch rotor hub to rotate. The other side of the passive variable pitch rotor hub is rotatably connected to one side of the connecting rotor hub through a pair of rotor hub movable pins. A pair of blades of the passive variable pitch rotor blade layer of the coaxial dual-propeller UAV are installed on both sides of the connecting rotor hub. The pair of rotor hub movable pins are symmetrically located on both sides of the passive variable pitch rotor hub, and their axes coincide. After installation, the axis of the pair of rotor hub movable pins forms a set angle α with the axis of the passive variable pitch rotor blade layer of the coaxial dual-propeller UAV.

[0008] By adopting the above technical solution, when a single-layer variable-pitch coaxial dual-propeller UAV needs to move horizontally, the active variable-pitch propeller layer actively changes pitch under the drive of the rotating swashplate mechanism, generating a horizontal torque. The passive variable-pitch propeller layer is passively tilted under the passive action of aerodynamic force, generating a horizontal torque. At the same time, due to the action of gyro torque, a large reaction force is generated, which makes the UAV's controllability and flight stability worse.

[0009] A passive single-layer variable pitch mechanism is adopted, changing the fixed hub connection structure of the original passive variable pitch blade layer. A passive variable pitch hub and a pair of hub movable pins are added. The hub movable pins are arranged at a typical angle of 45° (or 135°) with the hub axis, so that it will also perform periodic pitch changes under the passive aerodynamic action, reducing the reaction torque caused by the gyro effect during high-speed flight, and giving the UAV better controllability and flight stability.

[0010] Optionally, a swashplate mechanism drives a pair of upper blades of a coaxial dual-propeller UAV to perform active periodic pitch changes. The pair of lower blades of the coaxial dual-propeller UAV are respectively installed at the blade mounting positions connected to the propeller hub. Under the passive action of aerodynamic forces, the pair of lower blades passively change pitch under the action of a pair of movable pins on the propeller hub.

[0011] Optionally, a swashplate mechanism drives a pair of lower blades of a coaxial dual-propeller UAV to perform active periodic pitch change. The pair of upper blades of the coaxial dual-propeller UAV are respectively installed at the blade mounting positions connected to the propeller hub. Under the passive action of aerodynamic force, the pair of upper blades passively change pitch under the action of a pair of movable pins of the propeller hub.

[0012] By adopting the above technical solution, the vertical position relationship between the active pitch control blade layer and the passive pitch control blade layer is not limited. The active pitch control blade layer can be on top or on the bottom without affecting the pitch control effect.

[0013] Optionally, the passive variable-pitch propeller hub has multiple connecting pins on its top and a pair of symmetrical hub movable pin connecting plates on both sides. Each pair of hub movable pin connecting plates has a pin hole. One end of the hub movable pin passes through the pin hole. The connecting hub has a pair of pin holes, and the axes of the pair of pin holes coincide with the included angle α. The other end of the hub movable pin passes through the pin hole of the connecting hub. Both ends of the hub movable pin are limited by retaining rings, and the hub movable pin can rotate freely within the pin holes of the hub movable pin connecting plates and the connecting hub.

[0014] By adopting the above technical solution, the passive single-layer variable pitch mechanism changes the original fixed hub connection structure of the passive variable pitch propeller layer. Multiple connecting pins at the top of the passive variable pitch hub are inserted into the power output turntable of the coaxial motor, making the rotation drive more reliable. A pair of hub movable pin connecting plates are used to connect a pair of hub movable pins below. Because the pitch change action of the passive variable pitch propeller layer is driven by aerodynamic force, no power is required. The hub movable pins can rotate freely in the pin holes of the hub movable pin connecting plates and the pin holes of the connecting hub, so that the passive variable pitch propeller layer can synchronously perform periodic pitch change under the passive action of aerodynamic force, reducing the reaction torque caused by the gyro effect during high-speed flight, and giving the single-layer variable pitch coaxial dual-propeller UAV better controllability and flight stability.

[0015] Optionally, the axis of a pair of hub pivot pins forms an angle α with the axis of the passive variable pitch blade layer of the coaxial dual-propeller UAV, or 120°≤α≤150°.

[0016] Optionally, the axis of a pair of hub pivot pins forms an angle α with the axis of the passive variable pitch blade layer of the coaxial dual-propeller UAV, where α = 45° or α = 135°.

[0017] By adopting the above technical solution, the rotor hub movable pin is arranged at a typical angle of 45° or 135° with the rotor hub axis, so that it will also perform periodic pitch changes under the passive action of aerodynamic force, and will not generate large torque due to the angle. This reduces the reaction torque caused by the gyro effect during high-speed flight, giving the UAV better controllability and flight stability.

[0018] Optionally, the swashplate mechanism includes a pitch control base, a first pitch control drive servo, a pitch control base, a second pitch control drive servo, a pitch control floating support base, a cage support frame, a blade support, a first link assembly, a second link assembly, a guide member, and a sliding rod.

[0019] One side of the variable pitch mount is drivenly connected to the rotary motor connecting seat to provide rotational power. The bottom of the housing of the first variable pitch drive servo is detachably mounted on the other side of the variable pitch mount. The bottom of the housing of the second variable pitch drive servo is detachably mounted on the upper surface of the housing of the first variable pitch drive servo. The bottom of the cage-type support frame is detachably mounted around the upper surface of the variable pitch mount. The variable pitch floating support is mounted on top of the cage-type support frame and located above the second variable pitch drive servo. The variable pitch floating support is provided with a shaft connector. The blade support includes a support base and a support rod. One end of the support rod is detachably mounted at the shaft connector, and the support base is mounted on the support... At the other end of the strut, the variable pitch floating support is fitted onto the outer wall of the strut and moves up and down on the outer wall of the strut. The two ends of the first linkage assembly are respectively connected to the power output shaft of the first variable pitch drive servo and one side of the variable pitch floating support. The two ends of the second linkage assembly are respectively connected to the power output shaft of the second variable pitch drive servo and one side of the variable pitch floating support. The guide has an elongated hole in the middle. One end of the guide is fixed on the variable pitch floating support and is located opposite the connection side of the first linkage assembly and the variable pitch floating support. One end of the sliding rod is connected to one side of the variable pitch floating support, and the other end moves up and down in the elongated hole of the guide.

[0020] By adopting the above technical solution, the main function of the rotating swashplate mechanism is to drive the active pitch variable blade layer to rotate normally while simultaneously driving the active pitch variable blade layer to rotate independently, so that the active pitch variable blade layer generates a horizontal torque. During normal operation, the power output shafts of the first and second pitch variable drive servos are both in a self-locking state. One output shaft of the coaxial motor drives the entire rotating swashplate mechanism and the active pitch variable blade layer to rotate through the rotary motor connector, providing lift. When horizontal movement is required, the active pitch variable blade layer needs to be driven to change pitch. The power output shaft of the first pitch variable drive servo can achieve the overall deflection of the active pitch variable blade layer through the first linkage assembly, thereby achieving single-layer active pitch change. The power output shaft of the second pitch variable drive servo can achieve the deflection of the active pitch variable blade layer at a certain angle through the second linkage assembly, thereby correcting the deflection of the main body attitude of the micro coaxial dual-propeller UAV caused by the offset lift.

[0021] The swashplate mechanism is a type of mechanism that enables active pitch control of a single blade layer; other implementations can also achieve single-layer active pitch control.

[0022] The pitch control method for a single-layer variable-pitch coaxial dual-propeller UAV adopts a pitch control structure for the single-layer variable-pitch coaxial dual-propeller UAV. The upper and lower power output shafts of the coaxial motor drive the rotating swashplate mechanism and the passive single-layer pitch control mechanism to rotate, thereby driving the active pitch control blade layer and the passive pitch control blade layer to rotate. When horizontal movement is required, the rotating swashplate mechanism drives the active pitch control blade layer of the coaxial dual-propeller UAV to perform active periodic pitch control.

[0023] The passive variable-pitch blade layer follows the active variable-pitch blade layer in passive periodic pitch change under the passive aerodynamic action, reducing the reaction torque caused by the gyro effect during flight.

[0024] Optionally, the active pitch blade layer is a pair of upper blades and the passive pitch blade layer is a pair of lower blades, or the active pitch blade layer is a pair of lower blades and the passive pitch blade layer is a pair of upper blades.

[0025] In summary, the present invention has at least one of the following beneficial technical effects:

[0026] This invention provides a pitch-changing structure and control method for a single-layer variable-pitch coaxial dual-propeller UAV. When the single-layer variable-pitch coaxial dual-propeller UAV needs to move horizontally, the active pitch-changing blade layer actively changes pitch under the drive of the rotating swashplate mechanism, generating a horizontal torque. The passive pitch-changing blade layer passively tilts under the passive aerodynamic action, generating a horizontal torque. The original fixed hub connection structure of the passive pitch-changing blade layer is changed to a passive single-layer pitch-changing mechanism, which adds a passive pitch-changing hub and a pair of hub movable pins. The hub movable pins are arranged at a typical angle of 45° or 135° with the hub axis, so that they also perform periodic pitch changes under the passive aerodynamic action. This reduces the reaction torque caused by the gyroscopic effect during high-speed flight, giving the UAV better maneuverability and flight stability. Attached Figure Description

[0027] Figure 1 This is a three-dimensional structural schematic diagram of the passive single-layer variable pitch mechanism for a single-layer variable pitch coaxial dual-propeller UAV of the present invention;

[0028] Figure 2 This is a top view of the passive single-layer variable pitch mechanism for a single-layer variable pitch coaxial dual-propeller UAV of the present invention.

[0029] Figure 3 This is a schematic diagram of the variable pitch structure of the rotor hub of the present invention, which is used for a single-layer variable pitch coaxial dual-propeller UAV, with the movable pin of the rotor hub and the rotor hub axis arranged at a typical value of 45°.

[0030] Figure 4 This is a schematic diagram of the overall state structure of the variable pitch structure of the present invention for a single-layer variable pitch coaxial dual-propeller UAV installed on the UAV;

[0031] Figure 5 This is a three-dimensional structural diagram of the overall state of the variable pitch structure of the present invention installed on a single-layer variable pitch coaxial dual-propeller UAV.

[0032] Figure 6 This is a schematic diagram of the variable pitch floating support structure of the active single-layer variable pitch mechanism for the variable pitch structure of a single-layer variable pitch coaxial dual-propeller UAV of the present invention.

[0033] Figure 7 This is a schematic diagram of the propeller support structure for the variable pitch structure of a single-layer variable pitch coaxial dual-propeller UAV of the present invention.

[0034] Explanation of reference numerals in the attached drawings: 1. Coaxial motor; 2. Passive single-layer variable pitch mechanism; 21. Passive variable pitch rotor hub; 211. Connecting pin; 212. Rotary hub movable pin connecting plate; 22. Rotary hub movable pin; 23. Connecting rotor hub; 30. Rotary motor connecting seat; 31. Variable pitch seat; 32. First variable pitch drive servo; 33. Variable pitch drive seat; 34. Second variable pitch drive servo; 35. Variable pitch floating support seat; 351. Shaft connector; 36. Cage support frame; 371. Support seat; 372. Support rod; 38. First linkage assembly; 39. Second linkage assembly; 40. Guide component; 41. Sliding rod; 100. Coaxial dual-propeller UAV; 102. Upper blade; 103. Lower blade. Detailed Implementation

[0035] The following combination Figures 1-7 The present invention will be described in further detail below.

[0036] This invention discloses a variable pitch structure and control method for a single-layer variable pitch coaxial dual-propeller unmanned aerial vehicle.

[0037] Reference Figure 1 - Figure 6 The variable pitch structure for a single-layer variable pitch coaxial dual-propeller UAV includes an active single-layer variable pitch mechanism and a passive single-layer variable pitch mechanism 2. The active single-layer variable pitch mechanism includes a rotary motor connecting seat 30 and a rotary swashplate mechanism. The rotary swashplate mechanism is connected to one side of the output shaft of the coaxial motor 1 of the coaxial dual-propeller UAV 100 via the rotary motor connecting seat 30. The rotary swashplate mechanism drives the active variable pitch propeller layer of the coaxial dual-propeller UAV 100 to perform active periodic variable pitch. The passive single-layer variable pitch mechanism 2 drives the passive variable pitch propeller layer of the coaxial dual-propeller UAV 100 to perform passive periodic variable pitch under the passive action of aerodynamic force.

[0038] The passive single-layer variable pitch mechanism 2 includes a passive variable pitch rotor hub 21, a pair of rotor hub movable pins 22, and a connecting rotor hub 23. The output shaft on the other side of the coaxial motor 1 of the coaxial dual-propeller UAV 100 is connected and installed to one side of the passive variable pitch rotor hub 21 to drive the passive variable pitch rotor hub 21 to rotate. The other side of the passive variable pitch rotor hub 21 is rotatably connected to one side of the connecting rotor hub 23 through a pair of rotor hub movable pins 22. A pair of blades of the passive variable pitch rotor blade layer of the coaxial dual-propeller UAV 100 are installed on both sides of the connecting rotor hub 23. The pair of rotor hub movable pins 22 are symmetrically located on both sides of the passive variable pitch rotor hub 21 and their axes coincide. After installation, the axis of the pair of rotor hub movable pins 22 forms a set angle α with the axis of the passive variable pitch rotor blade layer of the coaxial dual-propeller UAV 100.

[0039] When a single-layer variable-pitch coaxial dual-propeller UAV needs to move horizontally, the active variable-pitch propeller layer actively changes pitch under the drive of the rotating swashplate mechanism, generating a horizontal torque. The passive variable-pitch propeller layer is passively tilted under the passive action of aerodynamic force, generating a horizontal torque. At the same time, due to the action of gyro torque, a large reaction force is generated, which makes the UAV's controllability and flight stability worse.

[0040] A passive single-layer variable pitch mechanism 2 is adopted, which changes the fixed hub connection structure of the original passive variable pitch blade layer. A passive variable pitch hub 21 and a pair of hub movable pins 22 are added. The hub movable pins are arranged at a typical angle of 45° (or 135°) with the hub axis, so that it will also perform periodic pitch change under the passive aerodynamic action, reducing the reaction torque caused by the gyro effect during high-speed flight, and giving the UAV better controllability and flight stability.

[0041] The rotating swashplate mechanism drives a pair of upper blades 102 of the coaxial dual-propeller UAV 100 to perform active periodic pitch changes. A pair of lower blades 103 of the coaxial dual-propeller UAV 100 are respectively installed at the blade mounting positions connected to the rotor hub 23. Under the passive action of aerodynamic force, the pair of lower blades 103 are passively pitched by a pair of rotor hub movable pins 22.

[0042] The rotating swashplate mechanism drives a pair of lower blades 103 of the coaxial dual-propeller UAV 100 to perform active periodic pitch changes. A pair of upper blades 102 of the coaxial dual-propeller UAV 100 are respectively installed at the blade mounting positions connected to the rotor hub 23. Under the passive action of aerodynamic force, the pair of upper blades 102 are passively pitched by a pair of rotor hub movable pins 22.

[0043] The vertical relationship between the active and passive pitch control blade layers is not limited; the active pitch control blade layer can be on top or on the bottom without affecting the pitch control effect.

[0044] The passive variable pitch rotor hub 21 has multiple connecting pins 211 on its top and a pair of rotor hub movable pin connecting plates 212 symmetrically arranged on both sides. Each pair of rotor hub movable pin connecting plates 212 has a pin hole. One end of the rotor hub movable pin 22 passes through the pin hole. The connecting rotor hub 23 has a pair of pin holes, and the axes of the pair of pin holes coincide with the included angle α. The other end of the rotor hub movable pin 22 passes through the pin hole of the connecting rotor hub 23. Both ends of the rotor hub movable pin 22 are limited by retaining rings, and the rotor hub movable pin 22 can rotate freely in the pin holes of the rotor hub movable pin connecting plates 212 and the pin holes of the connecting rotor hub 23.

[0045] The passive single-layer variable pitch mechanism 2 changes the fixed hub connection structure of the passive variable pitch blade layer. The top of the passive variable pitch hub 21 has multiple connecting pins 211 inserted into the power output turntable of the coaxial motor 1, making the rotation drive more reliable. A pair of hub movable pin connecting plates 212 are used to connect a pair of hub movable pins 22 below. Because the pitch change action of the passive variable pitch blade layer is driven by aerodynamic force, no power is required. The hub movable pins 22 are located in the pin holes of the hub movable pin connecting plates 212 and the pin holes of the connecting hub 23 and can rotate freely. This allows the passive variable pitch blade layer to synchronously change pitch periodically under the passive action of aerodynamic force, reducing the reaction torque caused by the gyro effect during high-speed flight, and giving the single-layer variable pitch coaxial dual-propeller UAV better controllability and flight stability.

[0046] The axis of a pair of rotor hub movable pins 22 forms an angle α with the axis of the passive variable pitch blade layer of the coaxial dual-propeller UAV 100, or 120°≤α≤150°.

[0047] The axis of a pair of hub movable pins 22 forms an angle α with the axis of the passive variable pitch blade layer of the coaxial dual-propeller UAV 100, where α = 45° or α = 135°.

[0048] The rotor hub movable pin is arranged at a typical angle of 45° (or 135°) with the rotor hub axis, so that it will also perform periodic pitch changes under the passive action of aerodynamic forces, and will not generate large torque due to the angle. This reduces the reaction torque caused by the gyro effect during high-speed flight, giving the UAV better controllability and flight stability.

[0049] The swashplate mechanism includes a pitch control seat 31, a first pitch control drive servo 32, a pitch control drive seat 33, a second pitch control drive servo 34, a pitch control floating support seat 35, a cage support frame 36, a blade support, a first link assembly 38, a second link assembly 39, a guide 40, and a sliding rod 41.

[0050] One side of the variable pitch seat 31 is connected to the rotary motor connecting seat 30 for providing rotational power. The bottom of the housing of the first variable pitch drive servo 32 is detachably mounted on the other side of the variable pitch seat 31. The bottom of the housing of the second variable pitch drive servo 34 is detachably mounted on the upper surface of the housing of the first variable pitch drive servo 32. The bottom of the cage support frame 36 is detachably mounted around the upper surface of the variable pitch seat 31. The variable pitch floating support seat 35 is mounted on top of the cage support frame 36 and located above the second variable pitch drive servo 34. The variable pitch floating support seat 35 is provided with a shaft connector 351. The blade support includes a support base 371 and a support rod 372. One end of the support rod 372 is detachably mounted on the shaft connector 351, and the support base 371 is mounted on the support rod. At the other end of 372, the variable pitch floating support 35 is fitted onto the outer wall of the support rod 372 and moves up and down on the outer wall of the support rod 372. The two ends of the first linkage assembly 38 are respectively connected to the power output shaft of the first variable pitch drive servo 32 and one side of the variable pitch floating support 35. The two ends of the second linkage assembly 39 are respectively connected to the power output shaft of the second variable pitch drive servo 34 and one side of the variable pitch floating support 35. The guide member 40 has an elongated hole in the middle. One end of the guide member 40 is fixed on the variable pitch floating support 35 and is located opposite the connection side of the first linkage assembly 38 and the variable pitch floating support 35. One end of the sliding rod 41 is connected to one side of the variable pitch floating support 35, and the other end moves up and down in the elongated hole of the guide member 40.

[0051] The main function of the swashplate mechanism is to drive the active pitch variable blade layer to rotate while simultaneously driving it to rotate independently, thereby generating a horizontal torque. During normal operation, the power output shafts of the first pitch variable drive servo 32 and the second pitch variable drive servo 34 are both in a self-locking state. One output shaft of the coaxial motor 1 drives the entire swashplate mechanism and the active pitch variable blade layer to rotate through the rotary motor connector 30, providing lift. When horizontal movement is required, the active pitch variable blade layer needs to be driven to change pitch. The power output shaft of the first pitch variable drive servo 32 can achieve the overall deflection of the active pitch variable blade layer through the first linkage assembly 38, thus achieving single-layer active pitch variable. The power output shaft of the second pitch variable drive servo 34 can achieve the deflection of the active pitch variable blade layer at a certain angle through the second linkage assembly 39, thereby correcting the attitude deflection of the micro coaxial dual-propeller UAV body 100 caused by the offset lift.

[0052] The swashplate mechanism is a type of mechanism that enables active pitch control of a single blade layer; other implementations can also achieve single-layer active pitch control.

[0053] The pitch control method for a single-layer variable-pitch coaxial dual-propeller UAV adopts a pitch control structure for the single-layer variable-pitch coaxial dual-propeller UAV. The upper and lower power output shafts of the coaxial motor 1 drive the rotating swashplate mechanism and the passive single-layer pitch control mechanism 2 to rotate, thereby driving the active pitch control blade layer and the passive pitch control blade layer to rotate. When horizontal movement is required, the rotating swashplate mechanism drives the active pitch control blade layer of the coaxial dual-propeller UAV 100 to perform active periodic pitch control.

[0054] The passive variable-pitch blade layer follows the active variable-pitch blade layer in passive periodic pitch change under the passive aerodynamic action, reducing the reaction torque caused by the gyro effect during flight.

[0055] The active pitch blade layer consists of a pair of upper blades 102, and the passive pitch blade layer consists of a pair of lower blades 103, or the active pitch blade layer consists of a pair of lower blades 103, and the passive pitch blade layer consists of a pair of upper blades 102. Specific Implementation Example 1:

[0057] At a certain moment, the active variable pitch blade layer is the upper propeller assembly, and the passive variable pitch blade layer is the lower propeller assembly. The hub movable pin is arranged at a typical 45° angle with the hub axis. The flight control system controls the upper and lower power output shafts of the coaxial motor 1 to drive the rotating swashplate mechanism and the passive single-layer variable pitch mechanism 2 to rotate at a speed of up to 50 rpm. The flight control system controls the power output shaft of the first variable pitch drive servo 32 to rotate, which drives the variable pitch floating support 35 to deflect by 8° through the first linkage assembly 38. At this time, the active variable pitch blade layer performs periodic pitch changes with a pitch change angle of 8°. The active variable pitch blade layer and the passive variable pitch blade layer maintain a high speed of 50 rpm. The passive variable pitch blade layer follows the periodic pitch changes under the passive aerodynamic action with a pitch change angle of 6°. During the entire lateral movement process, the single-layer variable pitch coaxial dual-propeller UAV is smoothly controlled and flies stably. By reading the attitude data of the UAV flight control, the maximum sway amplitude is calculated to be less than 2%. Specific Implementation Example 2:

[0059] At a certain moment, the active variable pitch blade layer is the upper propeller assembly, the passive variable pitch blade layer is the lower propeller assembly, the rotor hub movable pin is arranged at a 10° angle with the rotor hub axis, the flight parameters and control parameters are consistent with specific embodiment 1, the single-layer variable pitch coaxial dual propeller UAV is not smoothly controlled during the entire lateral movement process, and the flight state shows obvious shaking. By reading the attitude data of the UAV flight control, it is calculated that the maximum shaking amplitude reaches 30%. Specific Implementation Example 3:

[0061] At a certain moment, the active variable pitch blade layer is the upper propeller assembly, and the passive variable pitch blade layer is the lower propeller assembly. The rotor hub movable pin is arranged at a 20° angle with the rotor hub axis. The flight parameters and control parameters are consistent with those of Specific Embodiment 1. During the entire lateral movement process, the single-layer variable pitch coaxial dual-propeller UAV is not smoothly controlled, and the flight state shows obvious shaking. By reading the attitude data of the UAV flight control, it is calculated that the maximum shaking amplitude reaches 20%. Specific Implementation Example 4:

[0063] At a certain moment, the active variable pitch blade layer is the upper propeller assembly, and the passive variable pitch blade layer is the lower propeller assembly. The rotor hub movable pin is arranged at a 30° angle with the rotor hub axis. The flight parameters and control parameters are consistent with those of Specific Embodiment 1. During the entire lateral movement process, the single-layer variable pitch coaxial dual-propeller UAV control experienced intermittent unevenness, and the flight state showed shaking. By reading the attitude data of the UAV flight control, it was calculated that the maximum shaking amplitude did not exceed 10%, which is within the acceptable range. Specific Implementation Example 4:

[0065] At a certain moment, the active variable pitch blade layer is the upper propeller assembly, and the passive variable pitch blade layer is the lower propeller assembly. The rotor hub movable pin is arranged at a 60° angle with the rotor hub axis. The flight parameters and control parameters are consistent with those of Specific Embodiment 1. During the entire lateral movement process, the single-layer variable pitch coaxial dual-propeller UAV experienced intermittent unevenness in control, and the flight state showed shaking. By reading the attitude data of the UAV flight control, it was calculated that the maximum shaking amplitude did not exceed 10%, which is within the acceptable range.

[0066] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A variable pitch structure for a single layer variable pitch coaxial twin propeller drone, characterized by: The application relates to a coaxial dual-propeller unmanned aerial vehicle (100) with a single-layer variable-pitch mechanism, which comprises an active single-layer variable-pitch mechanism and a passive single-layer variable-pitch mechanism (2). The passive single-layer variable-pitch mechanism (2) comprises a passive variable-pitch hub (21), a pair of hub movable pin shafts (22) and a connecting hub (23), one side of a power output shaft of the coaxial motor (1) of the coaxial dual-propeller unmanned aerial vehicle (100) is connected with one side of the passive variable-pitch hub (21) and drives the passive variable-pitch hub (21) to rotate, the other side of the passive variable-pitch hub (21) is rotatably connected with one side of the connecting hub (23) through the pair of hub movable pin shafts (22), and a pair of propellers of the passive variable-pitch propeller layer of the coaxial dual-propeller unmanned aerial vehicle (100) are installed on the two sides of the connecting hub (23). The top of the passive variable-pitch hub (21) is provided with a plurality of connecting pin shafts (211), and a pair of hub movable pin shaft connecting plates (212) are symmetrically arranged on the two sides; one end of the hub movable pin shaft (22) penetrates through the pin shaft hole, a pair of pin shaft holes are arranged on the connecting hub (23) and the shaft lines of the pin shaft holes coincide with the included angle alpha, the other end of the hub movable pin shaft (22) penetrates through the pin shaft hole of the connecting hub (23), the two ends of the hub movable pin shaft (22) are respectively limited by the stop ring, and the hub movable pin shaft (22) is freely rotatable in the pin shaft hole of the hub movable pin shaft connecting plate (212) and the pin shaft hole of the connecting hub (23); and the plurality of connecting pin shafts (211) of the top of the passive variable-pitch hub (21) are insertedly connected with the power output rotating disc of the coaxial motor (1).

2. The variable pitch structure for a single layer variable pitch coaxial twin propeller drone according to claim 1, wherein: The rotating swash plate mechanism drives a pair of upper propellers (102) of the coaxial dual-propeller unmanned aerial vehicle (100) to perform active periodic variable-pitch, and a pair of lower propellers (103) of the coaxial dual-propeller unmanned aerial vehicle (100) are respectively installed in propeller mounting positions of the connecting hub (23), and the pair of lower propellers (103) are passively pitched under the action of the pair of hub movable pin shafts (22) under the passive action of aerodynamic force.

3. The variable pitch structure for a single layer variable pitch coaxial twin propeller drone according to claim 1, wherein: The pair of lower blades (103) of the coaxial dual-propeller unmanned aerial vehicle (100) is driven by the swash plate mechanism to actively change the periodic pitch, and the pair of upper blades (102) of the coaxial dual-propeller unmanned aerial vehicle (100) is respectively installed in the blade mounting position of the connecting hub (23), and under the passive action of aerodynamic force, the pair of upper blades (102) is passively pitched under the action of the pair of hub movable pins (22).

4. The variable pitch structure for a single layer variable pitch coaxial twin propeller drone according to claim 1, wherein: The axis of the pair of hub movable pins (22) and the axis of the passive pitch blade layer of the coaxial dual-propeller unmanned aerial vehicle (100) form an angle α, 30°≤α≤60°, or 120°≤α≤150°.

5. The variable pitch structure for a single layer variable pitch coaxial twin propeller drone according to claim 1, wherein: The axis of the pair of hub movable pins (22) and the axis of the passive pitch blade layer of the coaxial dual-propeller unmanned aerial vehicle (100) form an angle α, α=45° or α=135°.

6. The variable pitch structure for a single layer variable pitch coaxial twin propeller drone according to claim 5, wherein: The swash plate mechanism includes a pitch seat (31), a first pitch driving rudder (32), a pitch driving seat (33), a second pitch driving rudder (34), a pitch floating support seat (35), a cage support frame (36), a blade support, a first connecting rod assembly (38), a second connecting rod assembly (39), a guide (40), and a sliding rod (41). One side of the pitch seat (31) is in transmission connection with the rotating motor connecting seat (30) for providing rotating power, the bottom of the shell of the first pitch driving rudder (32) is detachably installed on the other side of the pitch seat (31), the bottom of the shell of the second pitch driving rudder (34) is detachably installed on the upper surface of the shell of the first pitch driving rudder (32), the bottom of the cage support frame (36) is detachably installed around the upper surface of the pitch seat (31), the pitch floating support seat (35) is installed on the top of the cage support frame (36) and above the second pitch driving rudder (34), the pitch floating support seat (35) is provided with an axle connecting piece (351), the blade support includes a support seat (371) and a support rod (372), one end of the support rod (372) is detachably installed at the axle connecting piece (351), the support seat (371) is installed at the other end of the support rod (372), the pitch floating support seat (35) is sleeved on the outer wall of the support rod (372) and moves up and down on the outer wall of the support rod (372), the two ends of the first connecting rod assembly (38) are respectively connected with the power output shaft of the first pitch driving rudder (32) and one side of the pitch floating support seat (35), the two ends of the second connecting rod assembly (39) are respectively connected with the power output shaft of the second pitch driving rudder (34) and one side of the pitch floating support seat (35), the middle part of the guide (40) is provided with a long position hole, one end of the guide (40) is fixed on the pitch floating support seat (35) and located opposite to the side where the first connecting rod assembly (38) is connected with the pitch floating support seat (35), one end of the sliding rod (41) is connected with one side of the pitch floating support seat (35) and the other end moves up and down in the long position hole of the guide (40).

7. A variable pitch control method for a single layer variable pitch coaxial twin propeller drone, characterized in that: The variable-pitch structure of claim 6 is used for variable-pitch control of the single-layer variable-pitch coaxial dual-propeller unmanned aerial vehicle, the upper and lower power output shafts of the coaxial motor (1) drive the rotating swash plate mechanism and the passive single-layer variable-pitch mechanism (2) to rotate, thereby driving the active variable-pitch blade layer and the passive variable-pitch blade layer to rotate, when horizontal movement is required, the rotating swash plate mechanism drives the active variable-pitch blade layer of the coaxial dual-propeller unmanned aerial vehicle (100) to perform active periodic variable-pitch; The passive variable-pitch blade layer follows the active variable-pitch blade layer to perform passive periodic variable-pitch under the passive action of aerodynamic force, thereby reducing the reaction torque caused by the gyroscopic effect during flight.

8. The variable pitch control method for a single-layer variable pitch coaxial twin-propeller UAV according to claim 7, characterized in that: The active variable-pitch blade layer is a pair of upper blades (102), and the passive variable-pitch blade layer is a pair of lower blades (103), or the active variable-pitch blade layer is a pair of lower blades (103), and the passive variable-pitch blade layer is a pair of upper blades (102).

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