Pan-tilt mechanism

Abstract

The present invention discloses a pan-tilt mechanism, which includes a base, a first driving device, a control system, and a first damping structure. The first driving device includes a first motor, a first output gear, and a bracket. The first motor is fixed on the base, and the first motor is in transmission connection with the first output gear to drive the first output gear to rotate. The first output gear is rotatably mounted on the base. The bracket is fixed on the first output gear, and the bracket is used for mounting a photographing device. The control system includes a first encoder assembly and a controller. The first encoder assembly is electrically connected to the controller, and the controller is electrically connected to the first motor. The first damping structure is used to provide a frictional force that hinders the rotation of the first output gear, so that when the first motor stops working, the position of the first output gear remains unchanged. Compared with the prior art, the pan-tilt mechanism of the present invention can eliminate the influence of backlash on the position accuracy of the pan-tilt mechanism.

Description

Technical Field

[0001] The present invention relates to the technical field of video acquisition, in particular to a pan-tilt mechanism. Background Art

[0002] A gimbal (pan / tilt head) is a supporting platform for a camera, typically consisting of a drive unit and a control system. The drive unit includes a motor, which is used to rotate the camera. In existing technologies, the control system typically uses an encoder to monitor the angular displacement of the motor's output shaft and calculates the camera's angular displacement based on this information. However, due to backlash, there is a certain discrepancy between the camera's actual rotation angle and the calculated angle, reducing the positioning accuracy of the gimbal mechanism. Summary of the Invention

[0003] The object of the present invention is to provide a pan-tilt mechanism for eliminating the influence of return clearance on the position accuracy of the pan-tilt mechanism.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention discloses a pan-tilt mechanism, comprising: a base;

[0006] a first driving device, comprising a first motor, a first output gear, and a bracket; the first motor is fixed to the base and is in transmission connection with the first output gear to drive the first output gear to rotate; the first output gear is rotatably mounted on the base; the bracket is fixed to the first output gear, and the bracket is used to mount the photographing device;

[0007] a control system comprising a first encoder assembly and a controller, wherein the first encoder assembly is electrically connected to the controller, and the controller is electrically connected to the first motor; the first encoder assembly is used to monitor the actual angle of the first output gear and transmit it to the controller, and the controller is used to control the movement of the first motor;

[0008] The first damping structure is used to provide a friction force that hinders the rotation of the first output gear, so that the position of the first output gear remains unchanged when the first motor stops working.

[0009] Preferably, the first damping structure includes a damping member, and the damping member is in contact with the base and the first output gear at the same time.

[0010] Preferably, the first damping structure further includes a locking member, and the locking member is used to apply a locking force that brings the first output gear and the base closer to each other, so that the first output gear and the base squeeze the damping member.

[0011] Preferably, the locking member is fixedly connected to the first output gear;

[0012] The first encoder assembly includes a first magnetic encoder and a first magnet. The first magnet is fixedly connected to the locking member, and the first magnetic encoder is fixed to the base; the first output gear, the first magnet, and the first magnetic encoder are coaxial.

[0013] Preferably, the locking member includes a mounting seat and a countersunk head screw; the mounting seat is in sliding contact with the side of the base away from the first output gear; the shank of the countersunk head screw passes through the mounting seat and is fixedly connected to the first output gear, and the head of the countersunk head screw abuts against the mounting seat to fixedly connect the first output gear to the mounting seat; the first magnet is fixed to the mounting seat; the mounting seat, the countersunk head screw, and the first magnet are coaxial.

[0014] Preferably, the pan-tilt mechanism further includes a second driving device, and the second driving device includes a second motor and a second output gear; the second motor is fixed to the bracket, and the second motor is in transmission connection with the second output gear to drive the second output gear to rotate; the axis of the second output gear is perpendicular to the axis of the first output gear;

[0015] The second output gear is used to be fixedly connected to the photographing device to drive the photographing device to rotate; the bracket is used to be rotatably connected to the photographing device to support the photographing device;

[0016] The control system includes a second encoder assembly. The second encoder assembly is electrically connected to the controller, and the controller is electrically connected to the second motor; the second encoder assembly is used to monitor the actual angle of the second output gear and transmit it to the controller, and the controller is used to control the operation of the second motor.

[0017] Preferably, the pan-tilt mechanism further includes a second damping structure, and the second damping structure is used to provide a frictional force that hinders the rotation of the second output gear, so that when the second motor stops working, the position of the second output gear remains unchanged.

[0018] Preferably, the second damping structure is an interference fit structure between the second output gear and the bracket.

[0019] Preferably, the second encoder assembly includes a second magnetic encoder and a second magnet. The second magnet is fixedly connected to the second output gear, and the second magnetic encoder is fixed to the bracket; the second output gear, the second magnet, and the second magnetic encoder are coaxial.

[0020] Preferably, the controller includes a motor drive PCB fixed to the base;

[0021] The first encoder assembly is electrically connected to the motor drive PCB, and the motor drive PCB is electrically connected to the first motor;

[0022] A pitch detection PCB is fixed on the bracket. The second encoder assembly is electrically connected to the pitch detection PCB, the pitch detection PCB is electrically connected to the motor drive PCB, and the motor drive PCB is electrically connected to the second motor.

[0023] The present invention has achieved the following technical effects compared with the prior art:

[0024] In the present invention, the control system does not monitor the angle of the output shaft of the first motor, but monitors the angle of the first output gear. Therefore, it is not affected by the backlash of the first driving device. When the first output gear rotates to the specified position, the first motor stops working, and the first output gear stops rotating under the action of friction and maintains its position unchanged. Therefore, the pan-tilt mechanism of this embodiment can improve the position accuracy of the first output gear, and further improve the position accuracy of the imaging device indirectly mounted on the first output gear. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0026] Figure 1 It is a top view of the pan-tilt mechanism of the embodiment of the present invention when both the horizontal and pitch rotations are 0°;

[0027] Figure 2 It is a sectional view in the front view direction of the pan-tilt mechanism of the embodiment of the present invention when both the horizontal and pitch rotations are 0°;

[0028] Figure 3 The front view of the pan-tilt mechanism of the embodiment of the present invention when both the horizontal and pitch rotations are 0°;

[0029] Figure 4 It is a right view of the pan-tilt mechanism of the embodiment of the present invention when both the horizontal and pitch rotations are 0°;

[0030] Figure 5 It is a left view of the pan-tilt mechanism of the embodiment of the present invention when both the horizontal and pitch rotations are 0°;

[0031] Figure 6The top view when the pan-tilt mechanism of the embodiment of the present invention rotates horizontally by 45° and pitches by 0°;

[0032] Figure 7 The top view when the pan-tilt mechanism of the embodiment of the present invention rotates horizontally by -45° and pitches by 0°;

[0033] Figure 8 The left view when the pan-tilt mechanism of the embodiment of the present invention rotates horizontally by 0° and pitches by -18°;

[0034] Figure 9 The left view when the pan-tilt mechanism of the embodiment of the present invention rotates horizontally by 0° and pitches by 18°;

[0035] Figure 10 The axonometric view when the pan-tilt mechanism of the embodiment of the present invention rotates horizontally by 0° and pitches by -18°;

[0036] Figure 11 The axonometric view of the pan-tilt mechanism of the embodiment of the present invention in another direction.

[0037] Explanation of reference numerals: 1 - base; 2 - U-shaped bracket with sector gear; 3 - fixed seat; 4 - shooting device; 5 - transmission cable; 6 - first motor; 7 - first worm; 8 - first double gear; 9 - motor wire of the first motor; 10 - first magnet; 11 - first magnetic encoder; 12 - second motor; 13 - second worm; 14 - second double gear; 15 - motor wire of the second motor; 16 - second magnet; 17 - second magnetic encoder; 18 - second output gear; 19 - mounting seat; 20 - damping member; 21 - motor drive PCB; 22 - pitch detection PCB; 23 - video cable; 24 - countersunk head screw. Detailed implementation manners

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0039] The purpose of the present invention is to provide a pan-tilt mechanism for eliminating the influence of backlash on the position accuracy of the pan-tilt mechanism.

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. The fixed connection in this embodiment can be a direct fixed connection (direct contact) or an indirect fixed connection (no contact). The fixed connection method can be a detachable fixed connection method such as fixing by fasteners, or a non-detachable fixed connection method such as welding or bonding. In the drawings of this embodiment, the first drive device is used to adjust the horizontal angle of the shooting device, and the second drive device is used to adjust the pitch angle of the shooting device.

[0041] Reference Figures 1 to 11 This embodiment provides a pan-tilt mechanism, including a base 1, a first driving device, a control system and a first damping structure.

[0042] Among them, the first driving device includes a first motor 6, a first output gear and a bracket. The first motor 6 is fixed on the base 1, and the first motor 6 is connected to the first output gear to drive the first output gear to rotate. The first output gear is rotatably mounted on the base 1. The bracket is fixed on the first output gear, and the bracket is used to install the shooting device 4. The shooting device 4 can output the shooting data through the video cable 23, or output the shooting data through wireless transmission. As a possible example, in this embodiment, the first output gear is a fan-shaped gear, and the bracket is a U-shaped bracket, and the opening of the U-shaped bracket faces the side away from the base 1. Since the bracket and the first output gear are fixed as a whole, the U-shaped bracket 2 with a fan-shaped gear is used to represent this whole in the accompanying drawings. According to different actual needs, those skilled in the art may also choose other forms of first output gears and brackets, for example, the first output gear is a circular gear, and the bracket is a square-shaped bracket.

[0043] The control system includes a first encoder assembly and a controller. The first encoder assembly is electrically connected to the controller, and the controller is electrically connected to the first motor 6. The first encoder assembly is used to monitor the actual angle of the first output gear and transmit it to the controller, which is used to control the operation of the first motor 6.

[0044] The first damping structure is used to provide a friction force that hinders the rotation of the first output gear, so that when the first motor 6 stops working, the position of the first output gear remains unchanged.

[0045] The working principle of the pan-tilt mechanism is as follows:

[0046] In this embodiment, the control system does not monitor the angle of the output shaft of the first motor 6 (the initial end of the transmission chain of the first driving device), but monitors the angle of the first output gear (the terminal end of the transmission chain of the first driving device). Therefore, it is not affected by the backlash of the first driving device. When the first output gear rotates to the specified position, the first motor 6 stops working, and the first output gear stops rotating under the action of friction and remains in place. Since the rotational speed of the first output gear is low and the friction is large, its inertial sliding distance is approximately zero. Therefore, the pan-tilt mechanism of this embodiment can improve the position accuracy of the first output gear, and further improve the position accuracy of the photographing device 4 indirectly mounted on the first output gear.

[0047] As a possible example, in this embodiment, the first damping structure includes a damping member 20, and the damping member 20 is in contact with both the base 1 and the first output gear at the same time. The damping member 20 can be made of rubber, or other materials such as silica gel. Those skilled in the art can select a material with a corresponding friction coefficient according to the actual friction coefficient requirements.

[0048] As a possible example, in this embodiment, a receiving groove for embedding the damping member 20 is formed between the first output gear and the base 1 to limit the position of the damping member 20.

[0049] As a possible example, in this embodiment, the damping member 20 is annular, and the receiving groove is correspondingly also annular. The damping member 20 and the receiving groove are coaxial with the first output gear. According to different actual needs, those skilled in the art can also select other shapes of the damping member 20. For example, there are multiple damping members 20 and they are square-shaped. The multiple square-shaped damping members are arranged in a circumferential array centered on the axis of the first output gear, and the base 1 is provided with receiving grooves corresponding to the square-shaped damping members.

[0050] As a possible example, in this embodiment, the first damping structure further includes a locking member for applying a locking force that makes the first output gear and the base 1 approach each other, so that the first output gear and the base 1 squeeze the damping member 20 to maintain a certain friction force. There are various types of locking members, and those skilled in the art can select according to actual needs. For example, the locking member can include a bolt, a nut and a spring. The nut is located on the side of the first output gear away from the base 1. The screw part of the bolt sequentially passes through the base 1 and the first output gear, and the screw part of the bolt is threadedly connected to the nut. The head part of the bolt is located on the side of the base 1 away from the first output gear. The spring is sleeved outside the screw part of the bolt, and both ends of the spring are abutted against the head part of the bolt and the base 1 respectively, and the spring is compressed. In this way, the locking force can be provided by the spring to make the first output gear and the base 1 squeeze the damping member 20.

[0051] As a possible example, in this embodiment, the locking member is fixedly connected to the first output gear so that the locking member and the first output gear rotate synchronously. The first encoder assembly includes a first magnetic encoder 11 and a first magnet 10. The first magnet 10 is fixedly connected to the locking member so that the first magnet 10 and the first output gear rotate synchronously. The first magnetic encoder 11 is fixed on the base 1. The first magnetic encoder 11 is used to sense the angle of the first magnet 10 and transmit the angle information to the controller. The first output gear, the first magnet 10 and the first magnetic encoder 11 are coaxial. Depending on actual needs, those skilled in the art may also choose other types of commonly used encoder assemblies, such as photoelectric encoder assemblies.

[0052] As a possible example, in this embodiment, the locking member includes a mounting seat 19 and a countersunk nail 24. The mounting seat 19 is in sliding contact with the side of the base 1 away from the first output gear. The body of the countersunk nail 24 passes through the mounting seat 19 and is fixedly connected to the first output gear. The head of the countersunk nail 24 abuts against the mounting seat 19 to securely connect the first output gear to the mounting seat 19. The first magnet 10 is fixed to the mounting seat 19. The mounting seat 19, the countersunk nail 24, and the first magnet 10 are coaxial.

[0053] As a possible example, in this embodiment, the mounting base 19 is provided with a mounting groove for mounting the first magnet 10, and the first magnet 10 is fixed in the mounting groove. The mounting base 19 has a groove on its surface facing the first output gear, and the first output gear has a protrusion on its surface facing the mounting base 19. The protrusion engages with the groove, and both the protrusion and the groove are coaxial with the first output gear.

[0054] As a possible example, in this embodiment, the pan-tilt mechanism further includes a second drive device, which includes a second motor 12 and a second output gear 18. The second motor 12 is fixed to the bracket, and the second motor 12 is transmission-connected to the second output gear 18 to drive the second output gear 18 to rotate. The axis of the second output gear 18 is perpendicular to the axis of the first output gear. When in use, the axis of the first output gear is usually set vertically, and the axis of the second output gear 18 is usually set horizontally. Depending on actual needs, those skilled in the art may also choose other angles.

[0055] The second output gear 18 is fixedly connected to the camera 4 to drive the camera 4 in rotation. The bracket is rotatably connected to the camera 4 to support the camera 4. Specifically, in this embodiment, the camera 4 is fixed within the fixing base 3, which is rotatably connected to the bracket, thereby achieving an indirect rotational connection between the bracket and the camera 4. It should be understood that the rotation axis of the rotational connection between the bracket and the camera 4 should be collinear with the axis of the second output gear 18.

[0056] The control system includes a second encoder assembly. The second encoder assembly is electrically connected to the controller, and the controller is electrically connected to the second motor 12. The second encoder assembly is used to monitor the actual angle of the second output gear 18 and transmit it to the controller, and the controller is used to control the operation of the second motor 12. Instead of monitoring the angle of the output shaft of the second motor 12 (the initial end of the transmission chain of the second driving device), the control system monitors the angle of the second output gear 18 (the terminal end of the transmission chain of the second driving device), so it will not be affected by the backlash of the second driving device.

[0057] In this embodiment, by simultaneously providing the first driving device and the second driving device, the pan-tilt mechanism can better adjust the angle of the photographing device 4.

[0058] As a possible example, in this embodiment, the pan-tilt mechanism further includes a second damping structure. The second damping structure is used to provide a frictional force that hinders the rotation of the second output gear 18, so that when the second motor 12 stops working, the position of the second output gear 18 remains unchanged. When the second output gear 18 rotates to a specified position, the second motor 12 stops working, and the second output gear 18 stops rotating under the action of the frictional force and remains in position.

[0059] As a possible example, in this embodiment, the second damping structure is an interference fit structure between the second output gear 18 and the bracket. According to different actual needs, those skilled in the art can also select other forms of the second damping structure. For example, a damping rubber ring is provided between the contact surfaces (rotating contact positions) of the second output gear 18 and the bracket.

[0060] As a possible example, in this embodiment, the second encoder assembly includes a second magnetic encoder 17 and a second magnet 16. The second magnet 16 is fixedly connected to the second output gear 18, the second magnetic encoder 17 is fixed on the bracket, and the second magnetic encoder 17 is used to sense the angle of the second magnet 16. The second output gear 18, the second magnet 16, and the second magnetic encoder 17 are coaxial. According to different actual needs, those skilled in the art can also select other types of common encoder assemblies, such as optoelectronic encoder assemblies, etc.

[0061] As a possible example, in this embodiment, the controller includes a motor drive PCB 21 (PCB refers to a printed circuit board) fixed on the base 1. The first encoder assembly is electrically connected to the motor drive PCB 21, and the motor drive PCB 21 is electrically connected to the first motor 6. The first encoder assembly transmits the actual angle of the first output gear to the motor drive PCB 21, and the motor drive PCB 21 calculates and processes the actual angle and then controls the operation of the first motor 6.

[0062] A pitch detection PCB 22 is fixed on the support. The second encoder assembly is electrically connected to the pitch detection PCB 22. The pitch detection PCB 22 is electrically connected to the motor drive PCB 21. The motor drive PCB 21 is electrically connected to the second motor 12. The second encoder assembly transmits the actual angle of the second output gear 18 to the pitch detection PCB 22, and then to the motor drive PCB 21 (specifically through the transmission cable 5). After calculating and processing the actual angle, the motor drive PCB 21 controls the operation of the second motor 12.

[0063] As a possible example, in this embodiment, both the first magnet 10 and the second magnet 16 are neodymium iron boron magnets. According to different actual needs, those skilled in the art can also choose other types of magnets.

[0064] As a possible example, in this embodiment, the first driving device includes a first worm 7, a first worm gear, a first input gear and a first pin shaft. The output shaft of the first motor 6 is fixedly connected to the first worm 7 and is coaxial. The first worm 7 meshes with the first worm gear. The first worm gear and the first input gear are fixed on the first pin shaft. The first input gear meshes with the first output gear. The second driving device includes a second worm 13, a second worm gear, a second input gear and a second pin shaft. The output shaft of the second motor 12 is fixedly connected to the second worm 13 and is coaxial. The second worm 13 meshes with the second worm gear. The second worm gear and the second input gear are fixed on the second pin shaft. The second input gear meshes with the second output gear 18. According to different actual needs, those skilled in the art can also choose other types of the first driving device and the second driving device, as long as they can drive the first output gear and the second output gear 18 to rotate. In this embodiment, both the first driving device and the second driving device use a worm and worm gear reduction mechanism. Those skilled in the art can also choose other types of reduction mechanisms or use a reduction motor with a built-in reduction mechanism. To reduce the size of the pan-tilt mechanism, the first motor 6 and the second motor 12 can be selected as micro permanent magnet stepper motors.

[0065] It should be noted that, in order to reduce weight and cost, in the first driving device and the second driving device, the transmission components other than the motor are usually made of plastic. The plastic worm gear is difficult to process and has a relatively high cost. The plastic helical gear is easy to process and has a relatively low cost. When the load is small, the helical gear can replace the worm gear. Therefore, in this embodiment, the first worm gear and the second worm gear can be worm gears or helical gears with a shape similar to that of a worm gear. When the first worm gear and the second worm gear are helical gears, the first worm gear and the first input gear form a first double gear 8, and the second worm gear and the second input gear form a second double gear 14.

[0066] As a possible example, in this embodiment, the photographing device 4 is equipped with a 14 mm lens. The entire length of the pan-tilt mechanism is 54 mm, the width is 52 mm, and the height is 35 mm. The horizontal rotation range of the photographing device 4 is from -45° to +45°, and the pitch rotation range is from -18° to +18°. The repeat positioning accuracy of the photographing device 4 is not greater than 0.15°, and the noise within 20 cm is not greater than 40 dB.

[0067] In this specification, specific examples are used to elaborate on the principles and implementation manners of the present invention. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present invention. At the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation on the present invention.

Claims

1. A pan-tilt mechanism, characterized in that, Comprising: Base; A first driving device, the first driving device including a first motor, a first output gear and a bracket; The first motor is fixed on the base, the first motor is in transmission connection with the first output gear to drive the first output gear to rotate; the first output gear is rotatably mounted on the base; the bracket is fixed on the first output gear, and the bracket is used for mounting a photographing device; A control system, the control system including a first encoder assembly and a controller, the first encoder assembly is electrically connected to the controller, and the controller is electrically connected to the first motor; the first encoder assembly is used for monitoring the actual angle of the first output gear and transmitting it to the controller, and the controller is used for controlling the operation of the first motor; A first damping structure, the first damping structure is used for providing a frictional force to impede the rotation of the first output gear, so that when the first motor stops working, the position of the first output gear remains unchanged; The first damping structure includes a damping member, and the damping member is in contact with both the base and the first output gear; The first damping structure further includes a locking member, and the locking member is used for applying a locking force to make the first output gear and the base approach each other, so that the first output gear and the base squeeze the damping member.

2. The pan-tilt mechanism according to claim 1, wherein, The locking member is fixedly connected to the first output gear; The first encoder assembly includes a first magnetic encoder and a first magnet, the first magnet is fixedly connected to the locking member, and the first magnetic encoder is fixed on the base; the first output gear, the first magnet and the first magnetic encoder are coaxial.

3. The pan-tilt mechanism according to claim 2, wherein The locking member includes a mounting seat and a countersunk head screw; the mounting seat is in sliding contact with the side of the base away from the first output gear; the shank of the countersunk head screw passes through the mounting seat and is fixedly connected to the first output gear, and the head of the countersunk head screw abuts against the mounting seat to fixedly connect the first output gear and the mounting seat; the first magnet is fixed on the mounting seat; the mounting seat, the countersunk head screw and the first magnet are coaxial.

4. The pan-tilt mechanism according to claim 1, wherein It further includes a second driving device, the second driving device including a second motor and a second output gear; the second motor is fixed on the bracket, and the second motor is in transmission connection with the second output gear to drive the second output gear to rotate; The axis of the second output gear is perpendicular to the axis of the first output gear; The second output gear is used for being fixedly connected to the photographing device to drive the photographing device to rotate; the bracket is used for being rotatably connected to the photographing device to support the photographing device; The control system includes a second encoder assembly, the second encoder assembly is electrically connected to the controller, and the controller is electrically connected to the second motor; the second encoder assembly is used for monitoring the actual angle of the second output gear and transmitting it to the controller, and the controller is used for controlling the operation of the second motor.

5. The pan-tilt mechanism according to claim 4, characterized in that, It further includes a second damping structure, and the second damping structure is used to provide a frictional force that hinders the rotation of the second output gear, so that when the second motor stops working, the position of the second output gear remains unchanged.

6. The pan-tilt mechanism according to claim 5, characterized in that, The second damping structure is an interference fit structure between the second output gear and the bracket.

7. The pan-tilt mechanism according to claim 4, characterized in that The second encoder assembly includes a second magnetic encoder and a second magnet. The second magnet is fixedly connected to the second output gear, and the second magnetic encoder is fixed on the bracket; the second output gear, the second magnet and the second magnetic encoder are coaxial.

8. The pan-tilt mechanism according to claim 4, characterized in that, The controller includes a motor drive PCB fixed on the base; The first encoder assembly is electrically connected to the motor drive PCB, and the motor drive PCB is electrically connected to the first motor; A pitch detection PCB is fixed on the bracket. The second encoder assembly is electrically connected to the pitch detection PCB, the pitch detection PCB is electrically connected to the motor drive PCB, and the motor drive PCB is electrically connected to the second motor.

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