Parallel robot mechanism with movable telecentric point

Abstract

According to the parallel robot mechanism with the movable telecentric point, the telecentric point is arranged on the fixed platform, deformation of the fixed platform is achieved based on the multi-rotating-pair branched chain of the fixed platform, and then free movement of the position of the telecentric point is achieved; the first branch chain, the second branch chain and the connecting rods for connecting the two platforms jointly form a first parallelogram, universal pairs at the two ends of the third branch chain are connected to the first parallelogram through the movable platform and the fixed platform correspondingly, and the first parallelogram can move in the two perpendicular directions at the same time based on the first branch chain and the second branch chain. Further, a telecentric point on the third branch chain can be driven to move around the telecentric point in rotation freedom degrees in two directions; the driving devices are arranged on the moving pairs of the three parallel branch chains, the three moving pairs are controlled to move synchronously, the distance between the movable platform and the fixed platform is adjusted, and then the size of the mechanism is adjusted.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent traffic control, and specifically to a parallel robot mechanism with a movable telecentric point. Background Art

[0002] At present, most of the robot mechanisms with movable telecentric points are generally serial mechanisms. The errors of serial mechanisms will accumulate step by step. Therefore, most of the telecentric movable parallel robot mechanisms based on serial mechanisms have low precision. The errors of parallel mechanisms are shared by multiple branches together. Therefore, the comprehensive error of the moving platform is small, which is suitable for the high-precision medical field. In addition, due to the closed-loop structure of the parallel mechanism, its stiffness characteristics are significantly higher than those of serial mechanisms, and the deformation is smaller under the same load. At present, only a small number of telecentric movable mechanisms are parallel mechanisms. For example, the patent with the application number CN202311418325.7 discloses a double-platform parallel robot mechanism that supports the movement of the telecentric point in three-dimensional space. However, in order to realize the movement of the secondary moving platform driving the instrument arm with three degrees of freedom of two rotations and one translation based on the telecentric point in space, a primary moving platform 5 and a secondary moving platform 10 are set in the mechanism. The primary branch is a P-R-Pa-R branch and the secondary branch is a U-R-R branch. Because there are many branches and relatively complex kinematic pairs in the mechanism, it is not applicable to all scenarios; at the same time, due to the relatively complex structure, the assembly difficulty of the mechanism is large, and the manufacturing cost is high. Summary of the Invention

[0003] In order to solve the problems that the complex structure of the existing telecentric movable parallel mechanism restricts the application scenarios and the assembly difficulty is large, the present invention provides a double-parallelogram telecentric movable parallel robot mechanism, which can meet the requirement of adjustable telecentric point, has a simple overall structure of the mechanism, reduces the manufacturing and assembly difficulty, and the structural dimensions can be flexibly adjusted, and can be applicable to more application scenarios.

[0004] The technical solution of the present invention is as follows: A parallel robot mechanism with a movable telecentric point, which includes: a moving platform and a fixed platform, and the moving platform and the fixed platform are connected through parallel branches; It is characterized in that: the parallel branches include: a first branch, a second branch and a third branch; the structures of the three parallel branches are the same and are arranged parallel to each other; the three parallel branches are all based on UPU branches; The UPU branch includes: a universal joint one, a branch moving pair and a universal joint two connected in sequence; The first branch and the second branch are connected through two platform connecting linkages, and the first branch, the second branch and the two platform connecting linkages together form a first parallelogram; the four universal joints are respectively located at the four vertices of the first parallelogram; Both the moving platform and the fixed platform are realized based on multi-revolute-joint branches; Each of the multi-revolute-joint branches includes N platform revolute joints connected in sequence. The first and the last platform revolute joints in the multi-revolute-joint branch are simultaneously connected to the same platform connecting link. Another set of adjacent platform revolute joints are connected through a rotating shaft of the universal joint in the third branch. The remaining adjacent platform revolute joints are connected based on in-platform links. The N platform revolute joints form an N-sided polygon; The rotating shafts of all the platform revolute joints are parallel to each other and are simultaneously perpendicular to the plane where the fixed platform is located; The fixed platform and the moving platform are respectively connected to a universal joint in the third branch and are arranged on the same side of the first parallelogram; The intersection point of the two rotating shafts of the universal joint in the third branch connected to the fixed platform is set as the telecentric point.

[0005] Its further features are as follows: In the multi-revolute-joint branch, the value of N is greater than or equal to 6; The lengths of the three parallel branches are the same; All the in-platform links are of equal length; When the moving platform and the fixed platform are in the default state, the intersection points of the three parallel branches and the fixed platform are respectively located at the three vertices of an equilateral triangle; Among the universal joints connected to both ends of the platform connecting link connected to the fixed platform, select one universal joint as the driving revolute joint for controlling the rotation of the telecentric point; a driving device is respectively connected to two mutually perpendicular rotating shafts of the driving revolute joint; Among the four platform revolute joints connected to the platform connecting link, select one platform revolute joint on each of the upper and lower platform connecting links as the driving prismatic joint for controlling the position movement of the telecentric point; driving devices are connected to the two driving prismatic joints; All the branch prismatic joints in the three branches are used as driving joints for dimension change, and a driving device is respectively connected to each driving joint for dimension change.

[0006] A parallel robot mechanism with a movable telecentric point provided in this application has its telecentric point set on a fixed platform. Based on the multi-revolute-joint linkages of the fixed platform, deformation of the fixed platform is achieved, and further free movement of the position of the telecentric point is realized. The first linkage, the second linkage, and the two platform-connecting linkages together form a first parallelogram. The universal joints at both ends of the third linkage are respectively connected to the first parallelogram through a moving platform and a fixed platform. The first parallelogram can generate movements in two mutually perpendicular directions based on the first linkage and the second linkage, and further can drive the telecentric point on the third linkage to achieve rotational freedom of movement in two directions around the telecentric point. By arranging drive devices on the prismatic joints of the three parallel linkages, controlling the three prismatic joints to perform synchronous movements, adjustment of the distance between the moving platform and the fixed platform is realized, and further adjustment of the size of the mechanism is achieved. The parallel robot mechanism in this application has a simple structure. Only revolute joints and universal joints can be used to achieve rotational freedom of movement in two directions around the telecentric point. Therefore, the overall complexity of the mechanism is not high, it is easy to assemble, and the uncertainty of the mechanism in singular configurations is reduced. At the same time, the three linkages can realize adjustment of the overall height of the mechanism, changing the height of the mechanism, so that the same mechanism can be applicable to more application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a schematic structural diagram of the double-parallelogram parallel mechanism with a movable telecentric point of this application; Figure 2 is a schematic diagram of specific structural markings of the structure of the double-parallelogram telecentric movable parallel robot mechanism of this application; Figure 3 is a schematic structural diagram of the fixed platform; Figure 4 is Figure 1 the enlarged structural diagram at position A in Figure 5 is Figure 1 the enlarged structural diagram at position B in Figure 6 is Action Example 1 of the structure of the double-parallelogram telecentric movable parallel robot mechanism; Figure 7 is Action Example 2 of the structure of the double-parallelogram telecentric movable parallel robot mechanism; Figure 8 is Action Example 3 of the structure of the double-parallelogram telecentric movable parallel robot mechanism; Figure 9 is a schematic structural diagram of the second parallelogram.

[0008] In the figure, 1 is the fixed platform; 11 is the first rotating pair of the fixed platform; 12 is the second rotating pair of the fixed platform; 13 is the third rotating pair of the fixed platform; 14 is the fourth rotating pair of the fixed platform; 15 is the fifth rotating pair of the fixed platform; 16 is the sixth rotating pair of the fixed platform; 17 is the first connecting rod of the fixed platform, 18 is the second connecting rod of the fixed platform, 19 is the third connecting rod of the fixed platform, 110 is the fourth connecting rod of the fixed platform, 111 is the fifth connecting rod of the fixed platform; 2 is the first branch chain; 21 is the first universal pair of the first branch chain; 22 is the sliding pair of the first branch chain; 23 is the second universal pair of the first branch chain; 231 is the first U-shaped connecting piece of the second universal pair of the first branch chain; 232 is the second U-shaped connecting piece of the second universal pair of the first branch chain; 3 is the second branch chain; 31 is the first universal pair of the second branch chain; 32 is the sliding pair of the second branch chain; 33 is the second universal pair of the second branch chain; 4 is the third branch chain; 41 is the first universal pair of the third branch chain; 42 is the sliding pair of the third branch chain; 421 is the tubular part; 422 is the rod-shaped part; 43 is the second universal pair of the third branch chain; 431 is the U-shaped connecting piece of the second universal pair of the third branch chain; 5 is the moving platform; 51 is the first rotating pair of the moving platform; 52 is the second rotating pair of the moving platform; 53 is the third rotating pair of the moving platform; 531 is the rotating shaft of the third rotating pair of the moving platform; 532 is the U-shaped connecting piece of the third rotating pair of the moving platform; 54 is the fourth rotating pair of the moving platform; 541 is the rotating shaft of the fourth rotating pair of the moving platform; 542 is the U-shaped connecting piece of the fourth rotating pair of the moving platform; 55 is the fifth rotating pair of the moving platform; 56 is the sixth rotating pair of the moving platform; 57 is the first connecting rod of the moving platform; 6 is the telecentric point. Detailed implementation mode

[0009] As Figures 1 to 9 shown, the present invention includes a parallel robot mechanism with a movable telecentric point 6, which includes: a fixed platform 1 and a moving platform 5, and the moving platform 5 and the fixed platform 1 are connected through parallel branch chains.

[0010] The parallel branch chains include: a first branch chain 2, a second branch chain 3 and a third branch chain 4; the structures of the three parallel branch chains are the same and are arranged in parallel with each other; the three parallel branch chains are all based on the UPU (universal pair - sliding pair - universal pair) branch chain. Because the structures of the three branch chains are that two universal pairs are connected based on a sliding pair, the three branch chains can be of equal length or unequal length. In this embodiment, in order to ensure reducing the moving error and improving the processing efficiency, the three parallel branch chains are set as branch chains of equal length. The structures of the rotating pairs, universal pairs and sliding pairs used in this application can all be realized based on the existing module products in the prior art.

[0011] The UPU branch chain includes: a universal pair one, a branch chain sliding pair, and a universal pair two connected in sequence. Specifically, the first branch chain 2 includes: a first branch chain universal pair one 21, a first branch chain sliding pair 22, and a first branch chain universal pair two 23; the second branch chain 3 includes: a second branch chain universal pair one 31, a second branch chain sliding pair 32, and a second branch chain universal pair two 33; the third branch chain 4 includes: a third branch chain universal pair one 41, a third branch chain sliding pair 42, and a third branch chain universal pair two 43.

[0012] The two rotating shafts of each universal pair: the m rotating shaft and the n rotating shaft are perpendicular to each other, forming a cross-shaped structure.

[0013] As Figure 2 In the shown embodiment, the first branch chain 2 and the second branch chain 3 are of equal length, and the first fixed-platform link 17 and the first moving-platform link 57 are of equal length. Then: the first branch chain 2, the second branch chain 3, the first fixed-platform link 17, and the first moving-platform link 57 together form a first parallelogram. The first branch chain universal pair one 21, the first branch chain universal pair two 23, the second branch chain universal pair one 31, and the second branch chain universal pair two 33 are located at the four vertex positions of the first parallelogram. The m rotating shafts of each universal pair: are parallel to each other and parallel to the plane where the fixed platform is located; based on the m rotating shafts of the four vertex universal pairs, the first parallelogram can deform at various angles within its plane. Based on the n rotating shafts of the four vertex universal pairs, the first parallelogram can swing at different angles with respect to the moving platform 1; among them, the m rotating shafts and the n rotating shafts of the four universal pairs are respectively marked as *m and *m in the figure.

[0014] In the first parallelogram, when the universal pairs are connected to each other by connecting rods, both ends of each rotating shaft are simultaneously connected to the two branches of the same U-shaped connecting piece, and the closed segments of the U-shaped connecting piece are connected based on the connecting rods. As Figure 4 Shown, it is a detailed structural schematic diagram of the first branch chain universal pair two 23. Both ends of the m rotating shaft (marked as 23m in the figure) of the first branch chain universal pair two 23 are respectively connected to the first branch chain universal pair two U-shaped connecting piece one 231, and both ends of the n rotating shaft (marked as 23n in the figure) are respectively connected to the first branch chain universal pair two U-shaped connecting piece two 232; the closed segment of the first branch chain universal pair two U-shaped connecting piece one 231 is connected to the second branch chain universal pair two 33 through the first moving-platform link 57.

[0015] The sliding pair in this embodiment includes a tubular part and a rod-shaped part. As Figure 2 Shown, taking the third branch chain sliding pair 42 as an example to illustrate the detailed structure of the sliding pair. The tubular part 421 is a tubular part with one end open. One end of the rod-shaped part 422 is inserted into the inner cavity of the tubular part 421, and the other end is connected to the third branch chain universal pair one 41. The closed end of the tubular part 421 is connected to the third branch chain universal pair two 43.

[0016] Between the first parallelogram and the third branch chain 4, the connection is realized through the moving platform 5 and the fixed platform 1; that is, two connection endpoints 171 are provided on the first link 17 of the fixed platform, which are respectively connected to the first rotating pair 11 of the fixed platform and the sixth rotating pair 16 of the fixed platform on the fixed platform 1; two connection endpoints are also provided at symmetric positions of the first link 57 of the moving platform with respect to the first link 17 of the fixed platform, which are respectively connected to the first rotating pair 51 of the moving platform and the sixth rotating pair 56 of the moving platform.

[0017] When the first link 17 of the fixed platform is installed through a mounting bracket (not marked in the figure), when the m-axis and n-axis of the universal joints at the four vertices of the first parallelogram swing at different angles and in different directions, the first parallelogram can drive the telecentric point 6 at the bottom of the third branch chain 4 to perform rotational freedom movement in two directions around the telecentric point through the fixed platform 1 and the moving platform 5.

[0018] Both the moving platform 5 and the fixed platform 1 are realized based on multi-rotating pair branch chains. Each multi-rotating pair branch chain includes N sequentially connected platform rotating pairs. The moving platform 5 and the fixed platform 1 are arranged in parallel, and the axes of all the platform rotating pairs in the moving platform 5 and the fixed platform 1 are parallel to each other and perpendicular to the plane where the fixed platform 1 is located at the same time. The first and last platform rotating pairs in the multi-rotating pair branch chain are simultaneously connected to the same platform connecting link, another group of adjacent platform rotating pairs are simultaneously connected to both ends of a rotating shaft of a third universal joint, and the remaining adjacent platform rotating pairs are connected based on connecting links, and the N sequentially connected platform rotating pairs form an N-sided polygon.

[0019] In this embodiment, the fixed platform 1 is connected to the first third universal joint 41, the moving platform 5 is connected to the second third universal joint 43, and the fixed platform 1 and the moving platform 5 are arranged on the same side of the first parallelogram. The intersection of the m-axis (marked as 41m in the figure) and the n-axis (marked as 41n in the figure) of the first third universal joint 41 connected to the fixed platform 1 is set as the telecentric point 6.

[0020] In order to form a polygon, the minimum value of N is 3. In this application, the shape of the fixed platform 1 is deformed by the rotation of the moving pair of the fixed platform 1 in its plane, thereby driving the position of the telecentric point 6 to change. The range that the position of the telecentric point 6 can reach is related to the side length of the fixed platform 1 and also related to the number of rotating pairs included in the fixed platform 1. However, if the value of N is too small, for example, when N is 3, it will cause many positions that the telecentric point 6 cannot reach, that is, there are too many dead points of the telecentric point 6. Therefore, in order to reduce the dead points of the telecentric point 6 within the range of the fixed platform 1, the value of N needs to be increased, but if the value of N is too large, the number of driving pairs for deforming the fixed platform 1 needs to be increased in order to achieve precise deformation. Therefore, in specific implementation, it is necessary to select the size of the side length of the fixed platform 1 and the number of moving pairs according to actual needs.

[0021] In this application, through multiple revolute pairs, the fixed platform and the moving platform are designed as a multi-link closed-loop structure, enabling it to achieve more complex output trajectories, reducing dead points, improving mechanical efficiency, lowering manufacturing and maintenance costs. The position of the centrode can be adjusted arbitrarily within the plane, with a large working space, and the adjustment of the centrode position is simple and easy to achieve.

[0022] In the multi-revolute pair branch chain of this embodiment, the value of N is equal to 6. Specifically, the side length dimension of the fixed platform is selected according to the actual height of the operating table. When N is 6, both platforms are planar six-bar mechanisms, and one driving pair is respectively arranged on the fixed platform 1 and the moving platform 5 to meet the actual working needs. Since the structures of the moving platform 5 and the fixed platform 1 are the same, both being 6R branches (6 revolute pairs), and their connection positions with the third branch chain 4 are also the same. As Figure 3 shown, taking the fixed platform 1 as an example to illustrate the structures of the two moving platforms and the fixed platform. Among the 6 sides of the fixed platform 1, there are four connecting rods with the same length: the second connecting rod 18 of the fixed platform, the third connecting rod 19 of the fixed platform, the fourth connecting rod 110 of the fixed platform, the fifth connecting rod 111 of the fixed platform. The other two sides are respectively between the two connection endpoints 171 on the first connecting rod 17 of the fixed platform and the m rotating shaft (marked as 41m in the figure) of the first universal pair 41.

[0023] The fixed platform 1 altogether includes 6 platform revolute pairs: the first revolute pair 11 of the fixed platform, the second revolute pair 12 of the fixed platform, the third revolute pair 13 of the fixed platform, the fourth revolute pair 14 of the fixed platform, the fifth revolute pair 15 of the fixed platform, and the sixth revolute pair 16 of the fixed platform. When the first revolute pair 11 and the sixth revolute pair 16 of the fixed platform are simultaneously connected to the first connecting rod 17 of the fixed platform, the m rotating shaft of the first universal pair 41 can be placed between any two adjacent revolute pairs except between the first revolute pair 11 and the sixth revolute pair 16 of the fixed platform. In this embodiment, in order to ensure the accuracy of the centrode movement, the m rotating shaft of the first universal pair 41 is arranged on the opposite side of the first connecting rod 17 of the fixed platform, so that the number of connecting rods on both sides of the centrode 6 is the same, ensuring more accurate control of the centrode 6 movement. Similarly, the m rotating shaft (marked as 43m in the figure) of the second universal pair 43 is arranged between the third revolute pair 53 and the fourth revolute pair 54 of the moving platform.

[0024] The revolute pairs in this application include: a linear rotating shaft and a U-shaped connecting piece. When the two ends of the m rotating shafts of the two universal pairs are respectively connected to the moving pairs, as Figure 5As shown, taking the m rotation axis of the third universal pair 43 as an example, the specific connection method will be described. The third rotating pair 53 of the moving platform includes: the rotating shaft 531 of the third rotating pair of the moving platform and the U-shaped connecting member 532 of the third rotating pair of the moving platform; and the fourth rotating pair 54 of the moving platform includes: the rotating shaft 541 of the fourth rotating pair of the moving platform and the U-shaped connecting member 542 of the fourth rotating pair of the moving platform; both ends of the n rotation axis (marked as 43n in the figure) of the third universal pair 43 are respectively connected to the inner side of the open end of the U-shaped connecting member 431 of the third link universal pair 2, and both ends of the m rotation axis (marked as 43m in the figure) of the third universal pair 43 are respectively connected to the closed section of the U-shaped connecting member 542 of the fourth rotating pair of the moving platform and the U-shaped connecting member 532 of the third rotating pair of the moving platform.

[0025] The position of the telecentric point is determined by the position constraint relationship provided by the moving platform and the fixed platform. Among the 4 platform rotating pairs connected to the connecting rod for platform connection, one platform rotating pair is selected from each of the upper and lower connecting rods for platform connection and set as the driving pair for moving to control the position movement of the telecentric point, and a driving device is provided on the driving pair for moving. As Figure 1 shown, in this embodiment, the first rotating pair 11 of the fixed platform and the first rotating pair 51 of the moving platform are selected as the driving pairs for moving to control the position movement of the telecentric point. The rotating shafts of the first rotating pair 11 of the fixed platform and the first rotating pair 51 of the moving platform are respectively connected to a driving motor to control the synchronous rotation of the first rotating pair 11 of the fixed platform and the first rotating pair 51 of the moving platform to achieve the position movement of the telecentric point 6. The motor connected to the first rotating pair 11 of the fixed platform is denoted as: driving motor E1, and the motor connected to the first rotating pair 5 of the moving platform is denoted as: driving motor E2. Once the telecentric point 6 moves to the preset position, the two driving motors are locked to lock the position of the telecentric point 6. Figure 1 At the marked positions E1~E4, they are the connection positions of the motor and the driving pair.

[0026] Figure 1 It is the initial state of the mechanism, that is, the first parallelogram is perpendicular to the horizontal plane, the first parallelogram is a rectangle with an interior angle of 90 degrees, and both the fixed platform 1 and the moving platform 5 are parallel to the horizontal plane; when the fixed platform 1 and the moving platform 5 are in the initial position, the telecentric point 6 is located on the left-right symmetry center line of the fixed platform 1. Based on Figure 1 this position, the driving motor E1 and the driving motor E2 rotate clockwise at the same time to move the position of the telecentric point 6 clockwise to Figure 6 as shown and then lock the two driving motors.

[0027] In order to ensure balanced force and improve the rigid strength of the overall structure, in this embodiment, when the parallel mechanism is in the initial state, a triangle is drawn with the three universal joints, namely the second-link universal joint two 32, the first-link universal joint two 22, and the third universal joint two 43 as the vertices. The positions of the three universal joints are just at the vertices of an equilateral triangle. Similarly, when the mechanism is in the initial state, the second-link universal joint one 31, the first-link universal joint one 21, and the third universal joint one 41 are also at the vertices of an equilateral triangle.

[0028] The position of the fixed-platform first connecting rod 17 is fixed. The rotation axes of all platform rotating pairs in the fixed platform 1 are perpendicular to the horizontal plane and also perpendicular to the fixed-platform first connecting rod 17. The lengths of the three parallel links are the same, which can ensure that the plane angle of the fixed platform does not change during the movement of the fixed-platform deformation telecentric point. When the position of the telecentric point 6 is locked, when the first parallelogram deforms, the moving platform 5 changes in position and angle along with the moving-platform first connecting rod 57. The moving platform 5 and the fixed platform 1 are connected by the third link 4, and the angle of the telecentric point 6 changes with the swing of the first parallelogram.

[0029] Among the link universal joints at both ends of the platform connecting link connected to the fixed platform 1, one link universal joint is selected as the rotating driving pair for controlling the rotation of the telecentric point; a driving motor is respectively arranged on two mutually perpendicular rotating shafts of the rotating driving pair. In this embodiment, the first-link universal joint one 21 is selected as the rotating driving pair; the n rotating shaft (marked as 21n in the figure) of the first-link universal joint one 21 is connected to a driving motor, and the motor is denoted as: motor E3; the m rotating shaft (marked as 21m in the figure) of the first-link universal joint one 21 is connected to a driving motor, and the motor is denoted as: motor E4.

[0030] Figure 6 The first parallelogram in is perpendicular to the horizontal plane. On the basis of the position in Figure 6 , motor E3 is started to drive the n rotating shaft of the first-link universal joint one 21 to rotate 30°, and then motor E3 stops. Then the first parallelogram rotates around the rotating shaft 21n to form an angle of 60° with the horizontal plane. The moving platform 5 changes in position and angle along with the moving-platform first connecting rod 57. As shown in Figure 7 , the moving platform 5 drives the third link 4 to change in angle. At this time, the telecentric point 6 generates a rotation around the rotating shaft 41m; a connection line L is obtained by connecting the intersection point of the two rotating shafts of the third universal joint two 43 and the telecentric point 6. The angle of the telecentric point 6 is as shown by the connection line L. At this time, the included angle between the connection line L and the XY plane is 60°.

[0031] In Figure 7On the basis of this, the motor E4 starts, driving the rotation of the m rotating shaft of the first branch universal pair 21. When the first branch 2 forms an angle of 60° with the horizontal plane, the motor E4 stops. Then the first parallelogram deforms as it rotates around the rotating shaft 21m, and the moving platform 5 changes its position and angle along with the first link 57 of the moving platform, as Figure 8 shown. The moving platform 5 drives the third branch 4 to change its angle. At this time, the telecentric point 6 rotates around the rotating shaft 41n; at this time, the angle between the connecting line L and the plane where ZX is located is 30°.

[0032] Driven by the motor E3 and the motor E4, the telecentric point 6 rotates around the rotating shafts m and n of the third branch universal hinge 41. At the same time, due to the structural locking between the fixed platform 1 and the moving platform 5, the telecentric point 6 does not move during the rotation. In practical applications, a moving pair can be added at the telecentric point, enabling the parallel structure in this application to achieve a motion of 2 rotations and 1 translation.

[0033] In this application, the branch moving pairs in the three branches are used as driving pairs for size change, and each branch moving pair is respectively connected to a driving device. The driving device connected to the branch moving pair can be realized based on the precision linear module that can achieve linear movement in the prior art. As Figure 1 shown, the linear drive modules E5 - E7 are respectively installed on the three moving pairs, and the specific connection method is realized according to the prior art. For example, the module body is set on the tubular part, and the output end is connected to the rod-shaped part. When it is necessary to adjust the distance between the moving platform 5 and the fixed platform 1, the three linear drive modules are synchronously driven, and the rod-shaped part is driven to move linearly in the inner cavity of the tubular part, then the distance between the two platforms can be changed, realizing the adjustment of the structural size of the parallel robot in this application. Furthermore, it is ensured that the technical solution of this application can be applied to more scenarios.

[0034] As Figure 9As shown, the three parallel branches are parallel to each other, and the fixed platform 1 is parallel to the moving platform 5. At this time, the plane formed by the third branch 4, the moving platform 5, the fixed platform 1, and the plane formed by the first branch 2 and the second branch 3 forms a second parallelogram. In this application, two parallelogram structures are designed in the branches, so that when the mechanism is in any position, the two parallelogram relationships still exist. Based on the two parallelograms, the telecentric point can be moved arbitrarily within the plane. And the three branch structures of this application are simple, consisting only of prismatic pairs and universal joints, so the overall complexity of the mechanism is not high, it is easy to assemble and reduce the uncertainty of the mechanism in singular configurations. The three branch structures in this application are simple and evenly distributed, with balanced force, improved stiffness, which is helpful for the modularization and standardization of the design and convenient for manufacturing. The branches of this application are parallel mechanisms, and the error is shared by multiple branches together. Therefore, the comprehensive error of the moving platform is small, which is suitable for the high-precision medical field. The parallel mechanism of this application is formed by three independent kinematic chains (branches) connecting the moving platform and the static platform together. The branches, the moving platform, and the fixed platform together form a closed-loop structure, and the load is shared by multiple branches together, with high overall stiffness. The serial mechanism in the prior art is an open-chain structure, where the joints and linkages are connected in series in sequence, and the end load needs to be transmitted to the base through all joints, resulting in error accumulation and deformation superposition, and weak rigidity. Therefore, the parallel mechanism of this application has a closed-loop structure, making its stiffness characteristics significantly higher than those of traditional serial mechanisms, with less deformation under the same load.

Claims

1. A parallel robot mechanism with a movable telecentric point, comprising: A moving platform and a fixed platform, wherein the moving platform and the fixed platform are connected via a parallel branch chain; The invention is characterized in that: the parallel branch chain comprises: a first branch chain, a second branch chain and a third branch chain; the three parallel branch chains have the same structure and are arranged in parallel with each other; the three parallel branch chains are all implemented based on the UPU branch chain; The UPU branch chain comprises: a universal joint first, a branch chain moving joint and a universal joint second which are connected in sequence; The first branch chain and the second branch chain are connected by two platform connecting rods, and the first branch chain, the second branch chain and the two platform connecting rods together form a first parallelogram; the four universal joints are respectively located at the four vertices of the first parallelogram; The moving platform and the fixed platform are both realized based on multiple rotating sub-branch chains; Each of the multi-rotation pair branches includes N platform rotation pairs connected in sequence, the first and last two platform rotation pairs in the multi-rotation pair branch are simultaneously connected to the same platform connection connecting rod, another group of adjacent platform rotation pairs are connected through a rotating shaft of a universal joint in the third branch, and the remaining adjacent platform rotation pairs are connected based on the platform inner connecting rod, and the N platform rotation pairs form an N-sided polygon; The rotation axes of all the platform rotation pairs are parallel to each other and perpendicular to the plane where the fixed platform is located; The fixed platform and the movable platform are respectively connected to a universal joint in the third branch chain, and are arranged on the same side of the first parallelogram; The intersection of the two rotating shafts of the universal joint in the third branch chain connected to the fixed platform is set as the telecentric point.

2. The parallel robot mechanism with a movable telecentric point according to claim 1, characterized in that: In the multi-rotation sub-branch chain, the value of N is greater than or equal to 6.

3. The parallel robot mechanism with a movable telecentric point according to claim 1, characterized in that: The three parallel-connected branches have the same length.

4. The parallel robot mechanism with a movable telecentric point according to claim 1, characterized in that: All of the inner links of the platform are of equal length.

5. The parallel robot mechanism with a movable telecentric point according to claim 1, characterized in that: When the moving platform and the fixed platform are in a default state, the intersection points of the three parallel branches and the fixed platform are respectively located at the three vertices of an equilateral triangle.

6. The parallel robot mechanism with a movable telecentric point according to claim 1, characterized in that: Among the universal joints connected at both ends of the platform connecting rod connected to the fixed platform, one universal joint is selected as a rotation driving pair for controlling the rotation of the telecentric point; a driving device is respectively connected to two mutually perpendicular rotating shafts of the rotation driving pair.

7. The parallel robot mechanism with a movable telecentric point according to claim 1, characterized in that: Among the four platform rotation pairs connected to the platform connecting rod, one platform rotation pair is selected on each of the upper and lower platform connecting rods, and is set as a moving driving pair for controlling the movement of the distal point position; and a driving device is connected to the two moving driving pairs.

8. The parallel robot mechanism with a movable telecentric point according to claim 1, characterized in that: The branch chain moving pairs in the three branches are all used as driving pairs for size change, and each of the driving pairs for size change is connected to a driving device respectively.

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