Mechanical arm device and control method

Abstract

The invention discloses a mechanical arm device and a control method, and relates to the technical field of semiconductor processing equipment. According to the mechanical arm, the first driving shaft and the second driving shaft are controlled to be matched with each other in a specific transmission ratio to achieve arm extending, arm retracting and rotating motion of the mechanical arm, and specifically, during arm extending, the transmission ratio of the first driving shaft to the second driving shaft is 1:-1; during arm retraction, the transmission ratio of the first driving shaft to the second driving shaft is-1: 1; when the relative positions of the first shell and the second shell are kept unchanged and the first shell and the second shell rotate, the transmission ratio of the first driving shaft to the second driving shaft is 1: 1. Through specific structural arrangement and simple cooperative control over the first driving shaft and the second driving shaft, an external controller only needs to send a rotation instruction following a fixed transmission ratio to the two driving shafts according to an expected motion mode (arm stretching or arm retracting or rotating); the response speed and reliability of the device can be improved, and meanwhile the overall cost is reduced; the overall structure is compact and reliability is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor processing equipment, and more particularly to a mechanical arm device and a control method. BACKGROUND

[0002] In the process of manufacturing semiconductor chips, wafers need to be transferred between different process equipment (such as ion implanters, measurement machines, etc.) stations with high precision, and this process relies on the coordinated movement of the mechanical arm to extend, retract and rotate. Currently, the precision requirements for wafer transfer in semiconductor manufacturing are increasingly stringent in order to avoid process defects or damage caused by wafer deviation; at the same time, in order to improve production efficiency, the mechanical arm structure is required to be simplified and responsive.

[0003] In the prior art, the mechanical arm for wafer transfer mostly detects the mechanical arm posture in real time through sensors, and adjusts the driving shaft angle with the help of complex algorithms to compensate for the movement deviation. However, this scheme has the following problems: there is a lack of transmission ratio constraint between the driving shafts, and the shafts are prone to deviate from the preset station direction during the extension or retraction process due to inter-shaft coordination errors, which requires repeated calibration, reducing the transfer efficiency; the mechanical arm posture stability is poor, which cannot guarantee the precise alignment of the wafer center and the mechanical arm center during the movement process, and posture deviation is prone to occur; in addition, the additional sensors and calibration algorithms not only increase the hardware cost and control complexity of the mechanical arm, but also may cause transfer failure due to sensor failure or algorithm delay, which is difficult to adapt to the high reliability requirements of semiconductor manufacturing.

[0004] Therefore, it is necessary to provide a new mechanical arm device and control method to meet the high precision, high reliability and low cost requirements of semiconductor wafer transfer. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a mechanical arm device and a control method to solve the problems in the prior art.

[0006] To achieve the above-mentioned purpose, the technical solution of the present application is as follows: In a first aspect of the present application, a mechanical arm device is provided, comprising: a first housing, a second housing, a mechanical arm for picking and placing wafers, a first transmission shaft, a second transmission shaft, a third transmission shaft, a first driving shaft, a second driving shaft, a first transmission mechanism and a second transmission mechanism; The first transmission shaft is fixedly arranged on one side inside the first housing, the second transmission shaft is fixedly arranged on the other side inside the first housing, and the upper end extends into the second housing, and the third transmission shaft is fixedly arranged on the other side inside the second housing. The first transmission mechanism comprises a first transmission wheel, a second transmission wheel and a first transmission member, the first transmission wheel is rotationally connected with the first transmission shaft through a first bearing, the second transmission wheel is rotationally connected with the second transmission shaft through a second bearing, the upper end of the second transmission wheel extends to the outside of the first shell and is fixedly connected with the bottom of the second shell, and a gap is formed between the outer periphery of the second transmission wheel and the first shell, and the first transmission member is arranged between the first transmission and the second transmission; The second transmission mechanism comprises a third transmission wheel and a second transmission member, the third transmission wheel is rotationally connected with the third transmission shaft through a third bearing, the upper end of the third transmission wheel extends to the outside of the second shell and is fixedly connected with the mechanical arm, and the second transmission member is arranged between the second transmission shaft and the third transmission wheel; The first drive shaft and the second drive shaft are arranged on one side of the first transmission shaft, the first drive shaft is fixedly connected with the bottom of the first shell, and the second drive shaft extends to the first shell through the center of the first drive shaft and the first transmission shaft and is fixedly connected with the first transmission wheel; The distance from the center line of the first transmission shaft to the center line of the second transmission shaft is equal to the distance from the center line of the second transmission shaft to the center line of the third transmission shaft; The first drive shaft and the second drive shaft are configured to rotate cooperatively at a preset transmission ratio to realize the stretching, shortening or rotating of the mechanical arm device, and the center line of the first transmission shaft, the center line of the third transmission shaft and the center line of the mechanical arm are coplanar.

[0007] Further, the first transmission wheel, the second transmission wheel and the third transmission wheel are all belt wheels, and the first transmission member and the second transmission member are both synchronous belts; or, the first transmission wheel, the second transmission wheel and the third transmission wheel are all gears, and the first transmission member and the second transmission member are both transmission chains.

[0008] Further, the ratio of the diameters of the outer peripheral working surfaces of the first transmission wheel and the second transmission wheel is 1:1.

[0009] Further, the ratio of the diameters of the outer peripheral working surfaces of the second transmission shaft and the third transmission wheel is 1:2.

[0010] Further, when the mechanical arm device moves to the position where the center line of the first transmission shaft coincides with the center line of the third transmission shaft, the first connecting line between the center line of the mechanical arm and the center line of the third transmission shaft is perpendicular to the second connecting line between the center line of the second transmission shaft and the center line of the third transmission shaft on the same plane, so that the first connecting line can always intersect with the center line of the first transmission shaft 29 when the mechanical arm device moves at any position.

[0011] In the second aspect, the application provides a control method based on the mechanical arm device, and the control method comprises the following steps: The first driving shaft and the second driving shaft are controlled to rotate at a preset transmission ratio. When the mechanical arm device is extended, the transmission ratio of the first driving shaft and the second driving shaft is controlled to be 1:-1. When the mechanical arm device is retracted, the transmission ratio of the first driving shaft and the second driving shaft is controlled to be-1:1. When the mechanical arm device rotates while keeping the relative position of the first shell and the second shell unchanged, the transmission ratio of the first driving shaft and the second driving shaft is controlled to be 1:1.

[0012] Further, when the initial relative angle between the first shell and the second shell is α, and the second driving shaft is controlled to rotate to an angle β between the first shell and the second shell, the first driving shaft and the second driving shaft are controlled to rotate in opposite directions at (α+β) / 2.

[0013] Further, during the extension, retraction or rotation of the mechanical arm device, the center line of the first transmission shaft, the center line of the third transmission shaft and the center line of the mechanical arm are always coplanar.

[0014] Compared with the prior art, the application has the following advantages: The mechanical arm device and the control method provided by the application can improve the wafer transmission efficiency, ensure the transmission stability and reliability, and improve the response speed and reliability of the device while reducing the overall cost. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a cross-sectional structural schematic diagram of the mechanical arm device.

[0016] Figure 2 is a three-dimensional structural schematic diagram of the mechanical arm device.

[0017] Figure 3 is a schematic diagram of the motion state of the mechanical arm device Figure 1 .

[0018] Figure 4 is a schematic diagram of the motion state of the mechanical arm device Figure 2 .

[0019] Figure 5is a schematic diagram of a motion state of a mechanical arm device of the present application Figure 3 . DETAILED DESCRIPTION

[0020] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details set forth in this description. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to unnecessarily obscure aspects of the present application.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0022] Embodiment 1 Reference Figures 1 to 5 As shown in the figure, the embodiment provides a mechanical arm device, comprising: A first housing 12, a second housing 20, a mechanical arm 26 for taking and placing a wafer, a first transmission shaft 11, a second transmission shaft 15, a third transmission shaft 21, a first drive shaft 27, a second drive shaft 28, a first transmission mechanism 19 and a second transmission mechanism 25; wherein the first housing 12 and the second housing 20 provide a closed installation space and a support reference for internal transmission components; The first transmission shaft 11 is fixedly arranged on one side inside the first housing 12, the second transmission shaft 15 is fixedly arranged on the other side inside the first housing 12, and the upper end extends into the second housing 20, and the third transmission shaft 21 is fixedly arranged on the other side inside the second housing 20; in Figure 1 The first transmission shaft 11 is located on the right side inside the first housing 12, and the second transmission shaft 15 is located on the left side inside the first housing 12, and the two are arranged oppositely; The first transmission mechanism 19 comprises a first transmission wheel 13, a second transmission wheel 16 and a first transmission member 18, the first transmission wheel 13 is rotatably connected with the first transmission shaft 11 through a first bearing 14, the second transmission wheel 16 is rotatably connected with the second transmission shaft 15 through a second bearing 17, the transmission wheel is connected with the corresponding transmission shaft through the bearing, which reduces the rotation friction coefficient and realizes flexible rotation of the transmission wheel on the corresponding transmission shaft, the upper end of the second transmission wheel 16 extends to the bottom of the second housing 20 outside the first housing 12 and is fixedly connected, and a gap is formed between the outer periphery of the second transmission wheel 16 and the first housing 12 (to avoid the influence of the first housing 12 on the rotation of the second transmission wheel 16), and the first transmission member 18 is arranged between the first transmission wheel 13 and the second transmission wheel 16; In the illustrated embodiment, the first transmission wheel 13 and the second transmission wheel 16 are both belt wheels, and the corresponding first transmission member 18 is a synchronous belt; the first transmission member 18 is wrapped around the outer peripheral working surfaces of the first transmission wheel 13 and the second transmission wheel 16 with constant tension and without relative sliding, that is, compared with the use of chains and gears, the present embodiment preferably adopts the mode of belt wheel transmission, which can meet the cleanliness of the wafer processing workshop; the belt wheel and the synchronous belt (mostly made of polyurethane / rubber material) have very small wear, do not need additional lubrication or only need a small amount of dry lubrication, and will not produce metal debris, lubricating oil leakage and other pollutants. Further, the engagement of the synchronous belt and the belt wheel has no rigid gap, the transmission ratio is accurate, and there will be no idling error (positioning lag caused by gear engagement gap) of gear transmission; in addition, the belt wheel and the synchronous belt structure are simple and light in weight, and can be flexibly arranged inside the two housings; and the maintenance is simple and the replacement cost is low.

[0023] Optionally, in some high load or high torque transmission scenarios, a gear and chain combination can be selected.

[0024] The second transmission mechanism 25 includes a third transmission wheel 22 and a second transmission member 24, the third transmission wheel 22 is rotationally connected with the third transmission shaft 21 through a third bearing 23, the upper end of the third transmission wheel 22 extends to the outside of the second housing 20 and is fixedly connected with the mechanical arm 26, and the second transmission member 24 is arranged around the second transmission shaft 15 and the third transmission wheel 22; similarly, in the present embodiment, the third transmission wheel 22 is preferably a belt wheel, and the second transmission member 24 is preferably a synchronous belt, that is, the second transmission member 24 is wrapped around the outer peripheral working surfaces of the second transmission shaft 15 and the third transmission wheel 22 with constant tension and without relative sliding, for transmitting power to the third transmission wheel 22; The first drive shaft 27 and the second drive shaft 28 are both arranged on one side of the first transmission shaft 11, the first drive shaft 27 is fixedly connected with the bottom of the first housing 12, the second drive shaft 28 extends through the center of the first drive shaft 27 and the first transmission shaft 11 to the first housing 12, and is fixedly connected with the first transmission wheel 13 for driving the first transmission wheel 13 to rotate; it can be understood that the center of the first drive shaft 27 and the first transmission shaft 11 are both formed with a through hole for the second drive shaft 28 to pass through, and a gap is also formed between the outer peripheral sidewall of the second drive shaft 28 and the inner wall of the through hole, so as to avoid the influence of the first drive shaft 27 and the first transmission shaft 11 on the rotation of the second drive shaft 28; the first drive shaft 27 and the second drive shaft 28 form a coaxial nested structure and do not affect each other, which can greatly optimize the installation space, make the driving structure more compact, and adapt to the narrow installation environment inside the equipment.

[0025] In the first transmission mechanism 19 and the second transmission mechanism 25, the ratio of the outer peripheral working surface diameter of the first transmission wheel 13 to the second transmission wheel 16 is 1:1, so that the speed and torque from the first transmission wheel 13 to the second transmission wheel 16 remain unchanged; the ratio of the outer peripheral working surface diameter of the second transmission shaft 15 to the third transmission wheel 22 is 1:2, so that the speed from the second transmission shaft 15 to the third transmission wheel 22 is halved and the torque is increased, which is beneficial to realize the pick-and-place of the wafer and also provides a prerequisite for the coordinated rotation of the subsequent two drive shafts (the first drive shaft 27 and the second drive shaft 28), ensuring the motion state of the end effector.

[0026] Optionally, a belt pulley can also be fixedly installed on the upper end of the second transmission shaft 15, so that the second transmission member 24 is arranged on the second transmission shaft 15, and at this time, the ratio of the diameter of the belt pulley on the upper end of the second transmission shaft 15 to the outer peripheral working surface of the third transmission wheel 22 is set to 1:2.

[0027] The distance from the center line 29 of the first transmission shaft 11 to the center line 30 of the second transmission shaft 15 is equal to the distance from the center line 30 of the second transmission shaft 15 to the center line 31 of the third transmission shaft 21; this can provide a prerequisite for the coordinated rotation of the subsequent two drive shafts (the first drive shaft 27 and the second drive shaft 28), reduce the posture deviation of the end effector, and also reduce the complexity of the control method during use, facilitating the debugging and maintenance of the device.

[0028] The first drive shaft 27 and the second drive shaft 28 are configured to be able to rotate coordinately at a preset transmission ratio, so that when the manipulator device is in the arm extension, arm retraction or rotation, the first transmission shaft center line 29, the third transmission shaft center line 31 and the manipulator center line 32 are coplanar, thereby realizing the accurate, efficient and stable pick-and-place of the wafer.

[0029] Reference Figure 2 As shown in the figure, in the embodiment, when the manipulator device moves to the position where the first transmission shaft center line 29 coincides with the third transmission shaft center line 31, on the same plane, the first connecting line 33 between the manipulator center line 32 and the third transmission shaft center line 31 is perpendicular to the second connecting line 34 between the second transmission shaft center line 30 and the third transmission shaft center line 31, so that the first connecting line 33 can always intersect with the first transmission shaft center line 29 when the manipulator device moves at any position.

[0030] In the embodiment, the first driving shaft 27 is driven to sequentially transmit power to the first housing 12, the second transmission shaft 15, the second transmission member 24, the third transmission wheel 22, and finally drive the first housing 12 to rotate while also driving the mechanical arm 26 to rotate; the second driving shaft 28 is driven to sequentially transmit power to the first transmission wheel 13, the first transmission member 18, the second transmission wheel 16, and finally drive the second housing 20 to rotate, thereby adjusting the angle between the second housing 20 and the first housing 12.

[0031] In the embodiment, based on the specific transmission ratios of the first transmission mechanism 19 and the second transmission mechanism 25, the preset transmission ratio of the first driving shaft 27 and the second driving shaft 28 is as follows: when the mechanical arm device needs to be controlled to perform an arm extension movement, the preset transmission ratio of the first driving shaft 27 and the second driving shaft 28 is 1:-1; when the mechanical arm device needs to be controlled to perform an arm retraction movement, the preset transmission ratio of the first driving shaft 27 and the second driving shaft 28 is set to-1:1; when the first housing 12 and the second housing 20 need to be kept in a relative position unchanged, the preset transmission ratio of the first driving shaft 27 and the second driving shaft 28 is 1:1.

[0032] In the embodiment, clockwise rotation is positive, and counterclockwise rotation is negative.

[0033] It can be understood that the above preset transmission ratio is set based on the specific structure of the mechanical arm device in the embodiment. When the mechanical arm device needs to perform different movement modes, the transmission ratio of the first driving shaft 27 and the second driving shaft 28 can be adjusted accordingly to achieve fast and accurate wafer picking and placing, that is, to achieve wafer transfer between different stations without the need for additional sensors for real-time monitoring and adjustment. Of course, when the transmission ratios of the first transmission mechanism 19 and the second transmission mechanism 25 in the mechanical arm device are different, the transmission ratio of the first driving shaft 27 and the second driving shaft 28 also needs to be adjusted adaptively, and the process is more complex. Therefore, in the embodiment, the transmission ratio of the first transmission mechanism 19 is set to 1:1, and the structure of the second transmission mechanism 25 is set to 1:2.

[0034] Embodiment 2 The embodiment provides a control method based on the mechanical arm device in embodiment 1. Clockwise rotation is positive, and counterclockwise rotation is negative. The control method comprises the following steps. The first driving shaft 27 and the second driving shaft 28 are controlled to rotate at a preset transmission ratio; wherein, When the mechanical arm device extends the arm, the transmission ratio of the first driving shaft 27 and the second driving shaft 28 is controlled to be 1:-1; When the mechanical arm device retracts the arm, the transmission ratio of the first driving shaft 27 and the second driving shaft 28 is controlled to be-1:1; When the mechanical arm device keeps the first shell 12 and the second shell 20 in the relative position unchanged and rotates, the transmission ratio of the first drive shaft 27 and the second drive shaft 28 is 1:1.

[0035] Specifically, referring to Figure 3 As shown, the mechanical arm device is in the initial position, at this time, the work station one 35 places a wafer 36, the mechanical arm extends the work station one 35 along the direction 37, takes the wafer, and then reverses the arm to the initial position along the direction 37, and then keeps the first shell 12 and the second shell 20 in the relative position unchanged (the included angle is α), rotates along the rotation direction 38 to the work station two 39, and extends the work station two 39 along the direction 40 to place the wafer.

[0036] When the mechanical arm is in any position, the first transmission shaft center line 29, the third transmission shaft center line 31 and the mechanical arm center line 32, the three center lines correspond to three collinear points in the same plane, that is, the first transmission shaft center line 29, the third transmission shaft center line 31 and the mechanical arm center line 32 are coplanar; it can ensure that the mechanical arm completes the taking and placing of the wafer at the highest speed.

[0037] That is, the extension, retraction and rotation movement of the mechanical arm all need the first drive shaft 27 and the second drive shaft 28 to cooperate to realize with a fixed transmission ratio.

[0038] Taking the extension of the mechanical arm along the direction 37 to the work station one 35 as an example: Counterclockwise is negative and clockwise is positive, for example, Figure 4 As shown, if the first drive shaft 27 is fixed, the second drive shaft 28 is rotated counterclockwise to the included angle between the first shell 12 and the second shell 20 is β, at this time, the rotation angle of the second drive shaft 28 is -(α+β), and the angle of the mechanical arm deviating from the direction 37 is γ.

[0039] According to the transmission ratio relationship of the first transmission mechanism 19 and the second transmission mechanism 25, that is, the transmission ratio of the first transmission wheel 13 and the second transmission wheel 16 in the first transmission mechanism 19 is 1:1, and the transmission ratio of the second transmission shaft 15 and the third transmission wheel 22 in the second transmission mechanism 25 is 1:2, it can be obtained that: γ=(α+β) / 2; At this time, the first drive shaft 27 and the second drive shaft 28 need to be rotated clockwise at the same time (α+β) / 2, as shown, Figure 5 Only in this way can the mechanical arm extend along the direction 37, that is, extend along the preset direction to take the wafer.

[0040] Therefore, when extending the arm: The rotation angle of the first drive shaft 27 is (α+β) / 2; The rotation angle of the second drive shaft 28 is -(α+β)+(α+β) / 2=-(α+β) / 2; When the arm is stretched, the transmission ratio of the first drive shaft 27 to the second drive shaft 28 is 1:-1; When the arm is retracted, the transmission ratio of the first drive shaft 27 to the second drive shaft 28 is-1:1; When the first housing 12 and the second housing 20 are kept in a relative position and rotated, the transmission ratio of the first drive shaft 27 to the second drive shaft 28 is 1:1.

[0041] In summary, in the embodiment, the wafer transmission efficiency can be improved, and the transmission stability and reliability can be ensured; the specific structure is combined with the simple cooperative control of the first drive shaft and the second drive shaft, so that the external controller only needs to send a rotation instruction following a fixed transmission ratio to the two drive shafts according to the expected motion mode (stretching the arm, retracting the arm, or rotating); the response speed and reliability of the device can be improved, and the overall cost is reduced; the overall structure is compact and reliable.

[0042] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0043] In the present application, unless otherwise specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise specified. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0044] In the description of the specification, the description of the terms "the embodiment", "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any suitable manner in at least one embodiment or example. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0045] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0046] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and simple improvement made on the essential content of the present application shall be included in the protection scope of the present application.

Claims

1. A robotic arm apparatus, characterized by, The utility model relates to a wafer transfer device, which comprises: a first housing (12), a second housing (20), a mechanical arm (26) for taking and placing a wafer, a first transmission shaft (11), a second transmission shaft (15), a third transmission shaft (21), a first drive shaft (27), a second drive shaft (28), a first transmission mechanism (19) and a second transmission mechanism (25); the first transmission shaft (11) is fixedly arranged on one side inside the first housing (12), the second transmission shaft (15) is fixedly arranged on the other side inside the first housing (12), and the upper end extends into the second housing (20), and the third transmission shaft (21) is fixedly arranged on the other side inside the second housing (20); the first transmission mechanism (19) comprises a first transmission wheel (13), a second transmission wheel (16) and a first transmission member (18), the first transmission wheel (13) is rotatably connected with the first transmission shaft (11) through a first bearing (14), the second transmission wheel (16) is rotatably connected with the second transmission shaft (15) through a second bearing (17), the upper end of the second transmission wheel (16) extends out of the first housing (12) and is fixedly connected with the bottom of the second housing (20), and a gap is formed between the outer periphery of the second transmission wheel (16) and the first housing (12), and the first transmission member (18) is arranged between the first transmission (13) and the second transmission (16); the second transmission mechanism (25) comprises a third transmission wheel (22) and a second transmission member (24), the third transmission wheel (22) is rotatably connected with the third transmission shaft (21) through a third bearing (23), the upper end of the third transmission wheel (22) extends out of the second housing (20) and is fixedly connected with the mechanical arm (26), and the second transmission member (24) is arranged between the second transmission shaft (15) and the third transmission wheel (22); the first drive shaft (27) and the second drive shaft (28) are arranged on one side of the first transmission shaft (11), the first drive shaft (27) is fixedly connected with the bottom of the first housing (12), and the second drive shaft (28) extends through the center of the first drive shaft (27) and the first transmission shaft (11) into the first housing (12) and is fixedly connected with the first transmission wheel (13); the distance from the center line (29) of the first transmission shaft (11) to the center line (30) of the second transmission shaft (15) is equal to the distance from the center line (30) of the second transmission shaft (15) to the center line (31) of the third transmission shaft (21); the first drive shaft (27) and the second drive shaft (28) are configured to rotate cooperatively at a preset transmission ratio, so that the center line (29) of the first transmission shaft (11), the center line (31) of the third transmission shaft (21) and the center line (32) of the mechanical arm (26) are coplanar when the mechanical arm device is stretching, retracting or rotating.

2. The robot device according to claim 1, characterized in that, The first transmission wheel (13), the second transmission wheel (16) and the third transmission wheel (22) are all belt wheels, and the first transmission member (18) and the second transmission member (24) are all synchronous belts; or, the first transmission wheel (13), the second transmission wheel (16) and the third transmission wheel (22) are all gear wheels, and the first transmission member (18) and the second transmission member (24) are all transmission chains.

3. The robotic arm device of claim 1, wherein, The ratio of the diameter of the outer peripheral working surface of the first transmission wheel (13) to the diameter of the outer peripheral working surface of the second transmission wheel (16) is 1:

1.

4. The robot device according to claim 3, characterized in that The ratio of the diameter of the outer peripheral working surface of the second transmission shaft (15) to the diameter of the outer peripheral working surface of the third transmission wheel (22) is 1:

2.

5. The robot device according to claim 4, characterized in that, When the mechanical arm device moves to the state that the first transmission shaft center line (29) coincides with the third transmission shaft center line (31), the first connecting line (33) between the mechanical arm center line (32) and the third transmission shaft center line (31) is perpendicular to the second connecting line (34) between the second transmission shaft center line (30) and the third transmission shaft center line (31) on the same plane.

6. A control method for the robot device according to claim 5, characterized by, The control method comprises: According to the movement mode of the mechanical arm device, the first drive shaft (27) and the second drive shaft (28) are controlled to rotate in a preset transmission ratio; wherein, When the mechanical arm device extends the arm, the transmission ratio of the first drive shaft (27) and the second drive shaft (28) is controlled to be 1:-1; When the mechanical arm device retracts the arm, the transmission ratio of the first drive shaft (27) and the second drive shaft (28) is controlled to be -1:1; When the mechanical arm device rotates while keeping the relative position of the first shell (12) and the second shell (20) unchanged, the transmission ratio of the first drive shaft (27) and the second drive shaft (28) is controlled to be 1:

1.

7. The control method according to claim 6, characterized by When the arm is extended, when the initial relative angle between the first shell (12) and the second shell (20) is α, and the second drive shaft (28) is rotated alone to the angle between the first shell (12) and the second shell (20) is β, the first drive shaft (27) and the second drive shaft (28) are controlled to rotate in opposite directions at the same time (α+β) / 2.

8. The control method according to claim 6, characterized by, During the process of extending the arm, retracting the arm or rotating the mechanical arm device, the first transmission shaft center line (29), the third transmission shaft center line (31) and the mechanical arm center line (32) are always coplanar.

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