A coaxial unmanned helicopter rotor control system

Abstract

The present application provides a coaxial unmanned helicopter rotor control system for controlling the flight attitude of the unmanned helicopter, the operating system includes: a swash plate, a torque arm and a steering gear, the torque arm and the steering gear are respectively connected to the two sides of the swash plate, and the steering gear is connected to the swash plate through a connecting rod; a joint bearing is arranged inside the swash plate, the joint bearing includes a joint bearing inner ring and a joint bearing outer ring, the joint bearing inner ring is integrally connected to the main shaft, and the joint bearing outer ring is rotatably connected to the outer peripheral side of the joint bearing inner ring. The control system of the present application has the characteristics of simple structure, easy assembly, high production efficiency, simple control and low cost.

Description

Technical Field

[0001] The present application relates to the technical field of unmanned helicopters, and in particular to a coaxial unmanned helicopter rotor control system. Background Art

[0002] At present, an unmanned helicopter includes an airframe, a power unit, a rotor system and a control system. The rotor system includes a hub and blades. The helicopter generates lift through rotating blades to balance weight and flight resistance, and generates control forces in the front, back, left and right directions. The control system is used to control the attitude and track of the helicopter and change the motion state of the helicopter. The traditional coaxial unmanned helicopter rotor control system includes components such as servos, variable pitch pull rods and automatic tilt devices. A large number of rod systems are mainly used to control the coaxial helicopter. This control system is currently very mature, but it also has some shortcomings: first, in the prior art, the swash plate that moves up and down along the axis requires at least three servos to drive its movement, which increases the weight of the product and increases the production cost; second, the two servos in the traditional operating system are distributed at an angle of 120 degrees, and the flight control algorithm of this arrangement is difficult; in addition, the traditional control system has a complex structure, is difficult to assemble, and has a high cost. It has high requirements for blade consistency, and high process requirements for miniaturization. Summary of the invention

[0003] The purpose of the present application is to provide a coaxial unmanned helicopter rotor control system, which has the characteristics of simple structure, easy assembly, high production efficiency, simple control and low cost.

[0004] To achieve the above-mentioned purpose, the present application provides a coaxial unmanned helicopter rotor control system, comprising: a swash plate, a torque arm and a servo.

[0005] The torque arm and the steering gear are respectively connected to two sides of the swash plate, and the steering gear is connected to the swash plate through a connecting rod;

[0006] A spherical bearing is arranged inside the swash plate, and the spherical bearing includes a spherical bearing inner ring and a spherical bearing outer ring. The spherical bearing inner ring is integrally connected to the main shaft of the unmanned helicopter, and the spherical bearing outer ring is rotatably connected to the outer peripheral side of the spherical bearing inner ring.

[0007] As above, wherein the inclined plate includes a fixed plate and a movable plate, the fixed plate is sleeved on the outer peripheral side of the outer ring of the spherical bearing, and the inner peripheral wall of the fixed plate is fixedly connected to the outer peripheral wall of the outer ring of the spherical bearing, the movable plate is rotatably connected to the fixed plate and is located on the outer peripheral side of the fixed plate, the fixed plate is connected to the servo gear, and the movable plate is connected to the torque arm.

[0008] As above, one end of the torque arm is connected to the propeller hub of the unmanned helicopter through a variable pitch rocker arm; and the other end is connected to the swash plate.

[0009] As above, wherein the fixed plate is connected with an anti-torsion arm.

[0010] As above, wherein the torque arm comprises a first torque arm and a second torque arm respectively connected to two ends of the hub, and the first torque arm and the second torque arm are respectively connected to two ends of the swash plate.

[0011] As above, wherein the steering gear comprises a first steering gear and a second steering gear, the first steering gear is connected to the swash plate via a first connecting rod; the second steering gear is connected to the swash plate via a second connecting rod.

[0012] As above, wherein the center line of the first steering gear and the center line of the second steering gear are arranged at an angle of 90 degrees.

[0013] As above, wherein the output end of the first servo is connected to the first connecting rod through a first swing rod, one end of the first swing rod is fixedly connected to the output end of the first servo, and the other end of the first swing rod is rotatably connected to the first connecting rod.

[0014] As above, wherein one end of the first connecting rod away from the first rocker arm is connected to the tilting plate through a fixed rod.

[0015] As above, wherein the output end of the second servo is connected to the second connecting rod through a second swing rod, one end of the second swing rod is fixedly connected to the output end of the second servo, and the other end of the second swing rod is rotatably connected to the second connecting rod.

[0016] The beneficial effects achieved by this application are as follows:

[0017] (1) The swash plate of the present application is connected to the two ends of the propeller hub through two torque arms respectively. The servo drives the swash plate to tilt. The swash plate does not move up and down along the main shaft, but rotates around the inner ring of the joint bearing inside it. In the prior art, the swash plate that moves up and down along the shaft requires at least three servos to drive its movement, while the swash plate of the present application rotates around the inner ring of the joint bearing inside it only requires two servos to drive it. The present application has the advantages of reducing production costs and reducing product weight.

[0018] (2) The center lines of the two servos of the present application are arranged at a 90-degree angle, which can achieve mechanical decoupling control. The two servos control the pitch and roll attitude of the drone respectively without interfering with each other. Compared with the traditional servos distributed at an angle of 120 degrees, the flight control algorithm of the present application is less difficult and the control is simpler.

[0019] (3) The present application adopts two motors and two servos to realize the functions of the traditional coaxial rotor system. The rotor control system has a simple structure and low cost. The miniaturization of the rotor control system has low process requirements and is simple to assemble. The product production efficiency is high. The rotor control system has low requirements for blade consistency, which greatly reduces the production cost and design iteration cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For those skilled in the art, other drawings can also be obtained based on these drawings.

[0021] Figure 1 The present invention is a schematic diagram of the three-dimensional structure of a coaxial unmanned helicopter rotor control system.

[0022] Figure 2 The present invention is a front view of a coaxial unmanned helicopter rotor control system.

[0023] Figure 3 The present invention is a schematic diagram of the internal structure of a swash plate of a coaxial unmanned helicopter rotor control system.

[0024] Figure 4 The present invention is a schematic diagram of the arrangement of a servo of a coaxial unmanned helicopter rotor control system.

[0025] Figure numerals: 1-hub center piece; 2-pitch hub; 3-swash plate; 4-torque arm; 5-servo gear; 6-main shaft; 7-motor; 8-connecting rod; 9-pitch rocker arm; 10-upper rotor; 11-anti-torque arm; 12-spherical bearing inner ring; 13-spherical bearing outer ring; 31-fixed plate; 32-moving plate; 33-fixed rod; 41-first torque arm; 42-second torque arm; 51-first servo gear; 52-second servo gear; 81-first connecting rod; 82-second connecting rod; 83-first rocker arm; 84-second rocker arm. DETAILED DESCRIPTION

[0026] The following is a clear and complete description of the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0027] like Figure 1-3As shown, a coaxial unmanned helicopter rotor control system is connected to the upper rotor 10 of the unmanned helicopter. The control system includes: a swash plate 3, a torque arm 4 and a steering gear 5. The torque arm 4 and the steering gear 5 are respectively connected to the two sides of the swash plate 3. The end of the torque arm 4 away from the swash plate 3 is connected to the propeller hub of the unmanned helicopter. The steering gear 5 is connected to the swash plate 3 through a connecting rod 8. A joint bearing is arranged inside the swash plate 3. The joint bearing includes a joint bearing inner ring 12 and a joint bearing outer ring 13. The joint bearing inner ring 12 is integrally connected to the main shaft 6. The joint bearing outer ring 13 is rotatably connected to the outer peripheral side of the joint bearing inner ring 12. The steering gear 5 drives the swash plate 3 to tilt at a certain angle through the connecting rod 8. The joint bearing outer ring 13 rotates and tilts at a certain angle relative to the joint bearing inner ring 12. After the swash plate 3 is tilted, the torque arm 4 drives the propeller hub to change pitch, thereby realizing the pitch or roll control of the unmanned helicopter.

[0028] like Figure 1 and 2 As shown, the hub includes a hub central piece 1 and a variable pitch hub 2, and the hub central piece 1 is sleeved on the main shaft 6; the main shaft 6 is connected to a motor 7; wherein the variable pitch hub 2 includes a first variable pitch hub and a second variable pitch hub symmetrically connected at both ends of the hub central piece 1; the motor 7 is sleeved on the main shaft 6, the stator of the motor 7 is connected to the main shaft, and the rotor is connected to the hub, and the motor rotates to drive the hub to rotate, and the main shaft 6 does not move. After the motor 7 rotates, it drives the hub central piece 1, the variable pitch hub 2, the torque arm 4 and the upper rotor 10 to rotate.

[0029] like Figure 1 As shown, the swash plate 3 is sleeved on the main shaft 6 and is spaced apart from the hub center piece 1. The side of the swash plate 3 close to the hub center piece 1 is connected to the variable pitch hub 2 through the torque arm 4 and the variable pitch rocker arm 9, and the other side is connected to the steering gear 5 through the connecting rod 8. After the steering gear 5 rotates, the swash plate 3 is driven to tilt at a certain angle through the connecting rod 8. After the swash plate 3 tilts, the torque arm 4 is driven to move, thereby driving the variable pitch rocker arm 9 and the variable pitch hub 2 to rotate, thereby changing the variable pitch angle of the upper rotor 10, and realizing the control of the flight attitude of the unmanned helicopter. The steering gear 5 controls the attitude of the swash plate 3 and the cyclic pitch of the rotor through the connecting rod 8, thereby controlling the flight attitude of the unmanned helicopter.

[0030] like Figure 2 As shown, one end of the torque arm 4 close to the variable pitch hub 2 is connected to the variable pitch hub 2 through the variable pitch rocker arm 9; the other end is connected to the swash plate 3. After the swash plate 3 is tilted, the torque arm 4 is driven to move a certain distance upward or downward, and the torque arm 4 drives the variable pitch rocker arm 9 to swing upward or downward at a certain angle. The variable pitch rocker arm 9 drives the variable pitch hub 2 to rotate a certain angle relative to the hub central part 1, and the variable pitch hub 2 drives the rotor at its tail to swing a certain angle relative to the horizontal direction, thereby realizing the change of the flight attitude of the unmanned helicopter.

[0031] According to a specific embodiment of the present invention, the pitch rocker arm 9 includes a first pitch rocker arm fixedly connected to the first pitch propeller hub and a second pitch rocker arm fixedly connected to the second pitch propeller hub, the center lines of the first pitch propeller hub and the second pitch propeller hub coincide, and the first pitch rocker arm and the second pitch rocker arm are respectively fixedly connected on both sides of the center lines of the first pitch rocker arm and the second pitch rocker arm.

[0032] like Figure 3 As shown, a spherical bearing is arranged inside the swash plate 3, and the spherical bearing includes a spherical bearing inner ring 12 and a spherical bearing outer ring 13. The spherical bearing outer ring 13 is sleeved on the outer periphery of the spherical bearing inner ring 12 and is rotatably connected with the spherical bearing inner ring 12. The spherical bearing inner ring 12 is integrally connected with the main shaft 6. After the motor 7 rotates, the main shaft 6 and the spherical bearing inner ring 12 are both stationary. The outer peripheral wall of the spherical bearing inner ring 12 is a first arc portion protruding outward from the wall, and the first arc portion is in the shape of an arc. The inner peripheral wall of the spherical bearing outer ring 13 is a second arc portion concave inward from the wall, and the second arc portion is in the shape of an arc. The first arc portion of the spherical bearing inner ring 12 is cooperatively connected with the second arc portion of the spherical bearing outer ring 13. The swash plate 3 will not slide up and down along the main shaft 6 to control the rotor collective pitch like a traditional rotor operating system. The rotor collective pitch refers to the angle between the center line of the blade cross section and the horizontal line. The rotor collective pitch control is achieved by changing the rotation speed of the motor 7.

[0033] After the swash plate 3 of the present invention is tilted, the blade angle of the rotor on the unmanned helicopter is changed, which refers to the angle between the propeller chord and the propeller rotation plane. The blade angle is changed to achieve cyclical pitch change of the rotor, thereby changing the lift at different positions of the upper rotor rotation plane to achieve changing the flight attitude of the helicopter, and then changing the flight direction of the unmanned helicopter by changing the lift direction. The cyclical pitch change of the rotor can change the roll and pitch attitude of the helicopter; the rise and descent of the unmanned helicopter is controlled by adjusting the rotor collective pitch to obtain different total lifts, thereby realizing the vertical take-off and landing of the unmanned helicopter, and the rotor collective pitch is achieved by adjusting the speed change of the motor 7.

[0034] like Figure 3As shown, the swash plate 3 includes a fixed plate 31 and a movable plate 32. The fixed plate 31 is sleeved on the outer peripheral side of the spherical bearing outer ring 13 and is fixedly connected to the spherical bearing outer ring 13; the movable plate 32 is sleeved on the outer peripheral side of the fixed plate 31 and is rotatably connected to the fixed plate 31. The steering gear 5 is connected to the fixed plate 31, and the torque arm 4 is connected to the movable plate 32. When the steering gear 5 rotates, the steering gear 5 drives the fixed plate 31 to tilt at a certain angle through the connecting rod 8, and the fixed plate 31 drives the spherical bearing outer ring 13 to tilt at a certain angle relative to the spherical bearing inner ring 12. The fixed plate 31 and the spherical bearing outer ring 13 do not rotate with the hub central part 1, but only tilt at a certain angle relative to the spherical bearing inner ring 12 driven by the steering gear 5. After the fixed plate 31 tilts at a certain angle, it drives the movable plate 32 to tilt at a certain angle. After the movable plate 32 tilts at a certain angle, it drives the torque arm 4 to move. After the swash plate 3 tilts, it drives the variable pitch hub 2 to rotate through the torque arm 4 and the variable pitch rocker arm 9, thereby controlling the pitch and roll attitude of the unmanned helicopter.

[0035] like Figure 2 As shown, the moving plate 32 is connected to the torque arm 4, the torque arm 4 is connected to the propeller hub, and the propeller hub is connected to the motor 7. When the motor 7 rotates, the main shaft 6 does not move, and the motor 7 drives the propeller hub, the torque arm 4 and the moving plate 32 to rotate. The moving plate 32 rotates relative to the fixed plate 31, and the fixed plate 31 is relatively fixed to the joint bearing and does not rotate with the moving plate 32.

[0036] According to other specific embodiments of the present invention, the moving plate 32 may be connected to a plurality of torque arms 4, two, three, four, or even more, and each torque arm 4 is connected to a hub and a blade.

[0037] like Figure 2 and Figure 3 As shown, the fixed plate 31 is connected to the anti-torsion arm 11, which is arranged at one end of the slanting plate 3 away from the servo 5 and is located in the same straight line direction as one of the servo 5. The anti-torsion arm 11 is fixed and used to prevent the fixed plate 31 from twisting. One end of the fixed plate 31 is connected to the anti-torsion arm 11 through a fixed rod 33, and the fixed rod 33 can only move up and down relative to the anti-torsion arm 11, but cannot deflect relative to the anti-torsion arm 11. The fixed rod 33 is fixedly connected to the fixed plate 31, thereby preventing the fixed plate 31 from deflecting.

[0038] like Figure 2 As shown, the torque arm 4 includes a first torque arm 41 and a second torque arm 42 respectively connected to the variable pitch hub 2 at both ends of the hub, the first torque arm 41 and the second torque arm 42 are respectively connected to the two ends of the swash plate 3, and the points where the first torque arm 41 and the second torque arm 42 are connected to the swash plate 3 are located in the same diameter direction of the swash plate 3.

[0039] like Figure 1 and Figure 4As shown, the steering gear 5 includes a first steering gear 51 and a second steering gear 52, wherein the first steering gear 51 is used to control the pitch action of the unmanned helicopter, and the second steering gear 52 is used to control the roll action of the unmanned helicopter.

[0040] like Figure 2 As shown, the first steering gear 51 is connected to the swash plate 3 through the first connecting rod 81; the second steering gear 52 is connected to the swash plate 3 through the second connecting rod 82, the first connecting rod 81 and the second connecting rod 82 are arranged parallel to the axis direction of the main shaft 6, and the bottom ends of the first connecting rod 81 and the second connecting rod 82 are connected to the steering gear 5. The first steering gear 51 drives the first connecting rod 81 to move up and down, and the second steering gear 52 is used to drive the second connecting rod 82 to move up and down, and the first connecting rod 81 and the second connecting rod 82 are used to drive the swash plate 3 to tilt at a certain angle.

[0041] like Figure 2 As shown, the top ends of the first connecting rod 81 and the second connecting rod 82 are connected to the fixed plate 31 through the fixed rod 33. The fixed plate 31 is arranged perpendicular to the axis direction of the main shaft 6, and the fixed rod 33 is connected to the edge of the fixed plate 31 in a direction parallel to the fixed plate 31. The fixed rod 33 is used to connect the first connecting rod 81 and the second connecting rod 82 to the ends of the swash plate 3. The fixed rod 33 is rod-shaped. After the fixed rod 33 is connected between the swash plate 3 and the first connecting rod 81 and the second connecting rod 82, the first connecting rod 81 and the second connecting rod 82 are at a distance from the swash plate 3, which makes it easier to drive the swash plate 3 to tilt. The force applied by the steering gear 5 does not need to be very large to tilt the swash plate 3 to a certain angle.

[0042] According to a specific embodiment of the present invention, the top end of the first connecting rod 81 is connected to the fixed plate 31 through the first fixed rod, and the top end of the second connecting rod 82 is connected to the fixed plate 31 through the second fixed rod, and the first fixed rod and the second fixed rod are arranged vertically. The first fixed rod and the second fixed rod are used to tilt the swash plate 3 at a certain angle in two vertical directions, wherein the tilt in one direction is used to make the unmanned helicopter perform a pitching action, and the tilt in the other direction is used to make the unmanned helicopter perform a rolling action.

[0043] like Figure 1 and Figure 4 As shown, the center line of the first steering gear 51 and the center line of the second steering gear 52 are arranged at an angle of 90 degrees, the center line of the first steering gear 51 is perpendicular to the center line of the second steering gear 52, and the straight line direction where the output shaft of the first steering gear 51 is located is perpendicular to the straight line direction where the output shaft of the second steering gear 52 is located. The positions of the first steering gear 51 and the second steering gear 52 are arranged reasonably, so that the tilting action of the swash plate 3 is highly reliable and stable.

[0044] like Figure 2 and Figure 4As shown, the output end of the first steering gear 51 is connected to the first connecting rod 81 through the first swing rod 83, one end of the first swing rod 83 is fixedly connected to the output end of the first steering gear 51, and the other end of the first swing rod 83 is rotatably connected to the first connecting rod 81. After the first steering gear 51 rotates, the first swing rod 83 is driven to rotate around the connection end of the first swing rod 83 and the first steering gear 51. After the first swing rod 83 rotates, it drives the first connecting rod 81 to move up and down, and the first connecting rod 81 drives the swash plate 3 to tilt at a certain angle.

[0045] According to a specific embodiment of the present invention, one end of the first connecting rod 81 away from the first swing rod 83 is connected to the fixed plate 31 of the tilting plate 3 through the fixed rod 33, the fixed rod 33 is fixedly connected to the fixed plate 31, and the first connecting rod 81 and the fixed rod 33 are ball-jointed.

[0046] like Figure 2 and Figure 4 As shown, the output end of the second steering gear 52 is connected to the second connecting rod 82 through the second swing rod 84, one end of the second swing rod 84 is fixedly connected to the output end of the second steering gear 52, and the other end of the second swing rod 84 is rotatably connected to the second connecting rod 82. After the second steering gear 52 rotates, the second swing rod 84 is driven to rotate around the connection end of the second swing rod 84 and the second steering gear 52. After the second swing rod 84 rotates, it drives the second connecting rod 82 to move up and down, and the second connecting rod 82 drives the swash plate 3 to tilt at a certain angle.

[0047] According to a specific embodiment of the present invention, one end of the second connecting rod 82 away from the second swing rod 84 is connected to the fixed plate 31 of the tilting plate 3 through the fixed rod 33, the fixed rod 33 is fixedly connected to the fixed plate 31, and the second connecting rod 82 and the fixed rod 33 are ball-jointed.

[0048] In the present invention, the lower rotor has no pitch-changing function and only provides lift. When the unmanned helicopter needs greater lift, the motor 7 connected to the upper rotor 10 and the motor 7 connected to the lower rotor increase their power, increasing the rotor speed, and the lift of the rotor system increases. The pitch and roll control of the unmanned helicopter is only independently completed by the upper rotor 10, and the yaw control of the unmanned helicopter is achieved by the inconsistent speed of the motor 7 connected to the upper rotor 10 and the motor 7 connected to the lower rotor, which leads to inconsistent torque.

[0049] The beneficial effects achieved by this application are as follows:

[0050] (1) The swash plate of the present application is connected to the two ends of the propeller hub through two torque arms respectively. The servo drives the swash plate to tilt. The swash plate does not move up and down along the main shaft, but rotates around the inner ring of the joint bearing inside it. In the prior art, the swash plate that moves up and down along the shaft requires at least three servos to drive its movement, while the swash plate of the present application rotates around the inner ring of the joint bearing inside it only requires two servos to drive it. The present application has the advantages of reducing production costs and reducing product weight.

[0051] (2) The center lines of the two servos of the present application are arranged at a 90-degree angle, which can achieve mechanical decoupling control. The two servos control the pitch and roll attitude of the drone respectively without interfering with each other. Compared with the traditional servos distributed at an angle of 120 degrees, the flight control algorithm of the present application is less difficult and the control is simpler.

[0052] (3) The present application adopts two motors and two servos to realize the functions of the traditional coaxial rotor system. The rotor control system has a simple structure and low cost. The miniaturization of the rotor control system has low process requirements and is simple to assemble. The product production efficiency is high. The rotor control system has low requirements for blade consistency, which greatly reduces the production cost and design iteration cycle.

[0053] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should fall within the scope of the patent coverage of the present invention.

Claims

1. A coaxial unmanned helicopter rotor control system, characterized in that: include: Swashplate, torque arm and servo, The torque arm and the steering gear are respectively connected to two sides of the swash plate, and the steering gear is connected to the swash plate through a connecting rod; A spherical bearing is arranged inside the swash plate, and the spherical bearing comprises a spherical bearing inner ring and a spherical bearing outer ring, the spherical bearing inner ring is integrally connected to the main shaft of the unmanned helicopter, and the spherical bearing outer ring is rotatably connected to the outer peripheral side of the spherical bearing inner ring; The tilting plate includes a fixed plate and a movable plate, wherein the fixed plate is sleeved on the outer peripheral side of the outer ring of the spherical bearing, and the inner peripheral wall of the fixed plate is fixedly connected to the outer peripheral wall of the outer ring of the spherical bearing, the movable plate is rotatably connected to the fixed plate and is located on the outer peripheral side of the fixed plate, the fixed plate is connected to the steering gear, and the movable plate is connected to the torque arm; One end of the torque arm is connected to the propeller hub of the unmanned helicopter through a variable pitch rocker arm; the other end is connected to the swash plate; The fixed plate is connected with an anti-torsion arm; The torque arm comprises a first torque arm and a second torque arm respectively connected to two ends of the hub, and the first torque arm and the second torque arm are respectively connected to two ends of the swash plate; The steering gear comprises a first steering gear and a second steering gear, wherein the first steering gear is connected to the swash plate via a first connecting rod; and the second steering gear is connected to the swash plate via a second connecting rod; The center line of the first steering gear and the center line of the second steering gear are arranged at an angle of 90 degrees.

2. The coaxial unmanned helicopter rotor control system according to claim 1, characterized in that: The output end of the first steering gear is connected to the first connecting rod through a first swing rod, one end of the first swing rod is fixedly connected to the output end of the first steering gear, and the other end of the first swing rod is rotatably connected to the first connecting rod.

3. The coaxial unmanned helicopter rotor control system according to claim 2, characterized in that: One end of the first connecting rod away from the first swing rod is connected to the tilting plate through a fixed rod.

4. The coaxial unmanned helicopter rotor control system according to claim 1, characterized in that: The output end of the second servo is connected to the second connecting rod through a second swing rod, one end of the second swing rod is fixedly connected to the output end of the second servo, and the other end of the second swing rod is rotatably connected to the second connecting rod.

Images