A two-mode parallel robot mechanism based on a reconfigurable motion platform

Abstract

The present application provides a two-mode parallel robot mechanism based on a reconfigurable moving platform, which adjusts the distance between the three V-shaped structures by using a moving pair on the moving platform, and controls whether the axes of the rotating shafts of the connecting rotating pairs intersect, thereby realizing the switching of the two motion modes of the reconfigurable moving platform: three rotations and two movements and one rotation and two movements; the present application can realize the reconstruction of the motion mode without changing the internal motion pairs of the branch chain, which reduces the complexity of the mode reconstruction, reduces the number of drive pairs in the branch chain, and thus reduces the moment of inertia during motion. The structures of the three branches of the present application are completely consistent and do not contain complex motion pairs, and the requirements for the stiffness and assembly accuracy of the mechanism components are relatively low. The overall structure is simple, easy to modularize and process and manufacture, and it can be applied to production and assembly tasks that require multiple motion modes.

Description

Technical Field

[0001] The present invention relates to the field of mechanism and robotics technology, and in particular to a two-mode parallel robot mechanism based on a reconfigurable motion platform. Background Art

[0002] Parallel robots play a crucial role in industrial production. Their advantages include high precision, high rigidity, fast response, and excellent load performance. They have become a research hotspot in the field of industrial robotics and have been successfully applied in machining, automated production lines, motion simulators, and other fields. Compared to traditional single-mode industrial robots, reconfigurable parallel robots can switch between different motion modes, possessing varying motion capabilities and properties, and adapting to diverse tasks. They are gaining increasing attention and favor among researchers.

[0003] However, existing reconfigurable parallel robot structures, such as the patent with publication number CN115026792A, have a large number of branched motion pairs within the mechanism, and the assembly conditions that need to be met are complex. At the same time, the switching of motion modes is achieved through structural changes within the branches. The control method of mode switching is relatively complex, and higher requirements are also placed on the stiffness and assembly accuracy of the mechanism, resulting in high costs and limited usage scenarios. Summary of the Invention

[0004] In order to solve the problems in the existing artificial reconfigurable parallel robot structure that the branch structure is more complex than the cross, and the motion mode switching achieved by the structural changes inside the branch leads to a more complicated control method, the present invention provides a two-mode parallel robot mechanism based on a reconfigurable motion platform, which has a simple structure, a small number of single-degree-of-freedom motion pairs, easy motion mode switching, good processing performance, and is easy to modularize and manufacture.

[0005] The technical solution of the present invention is as follows: a two-mode parallel robot mechanism based on a reconfigurable motion platform, comprising: a fixed base and a reconfigurable motion platform, characterized in that: the fixed base and the reconfigurable motion platform are connected by a first branch chain, a second branch chain, and a third branch chain, and the three branches have the same structure, namely, PRRRR branches;

[0006] The reconfigurable dynamic platform includes: three V-shaped structures and three dynamic platform connecting rods. The V-shaped structure includes two equal-length tubular sides with an included angle of 60 degrees. The shape and size of the inner cavity of the tubular side are adapted to the outer diameter of the dynamic platform connecting rod. Each dynamic platform connecting rod is arranged between two V-shaped structures. The two ends of each dynamic platform connecting rod are respectively inserted into one of the tubular sides with a clearance fit to form a moving pair for the dynamic platform. The three V-shaped structures and the three dynamic platform connecting rods form an equilateral triangle.

[0007] The first branch chain, the second branch chain and the third branch chain are respectively connected to a vertex of the reconfigurable dynamic platform through a connecting rotation pair.

[0008] It is further characterized by:

[0009] The branched chain structure includes: a first link, a second link, a third link, and a fourth link, one end of the first link is mounted on the fixed base via a branched chain moving pair, the other end of the first link is connected to one end of the second link to form a first revolving pair, the other end of the second link is connected to one end of the third link via a second revolving pair; the other end of the third link is connected to one end of the fourth link via a third revolving pair; the other end of the fourth link is connected to a vertex of the reconfigurable mobile platform via the connecting revolving pair;

[0010] The branch chain moving pair, the first rotating pair, and the second rotating pair form a plane pair, wherein the rotation axes of the first rotating pair and the second rotating pair are always parallel and perpendicular to the movement axis of the branch chain moving pair; the plane pair is connected to the third rotating pair and the connecting rotating pair, wherein the rotation axes of the third rotating pair and the connecting rotating pair always intersect at a point;

[0011] The motion axes of the three branch chain moving pairs are located in the same plane;

[0012] In the reconfigurable dynamic platform, any dynamic platform uses a mobile pair as a reconfigurable platform driving pair to control the configuration change of the reconfigurable platform to complete the mode switching of the mechanism;

[0013] The branch moving pair of the first branch chain, the branch moving pair of the second branch chain, the branch moving pair of the third branch chain, the first rotating pair of the first branch chain, and the third rotating pair of the first branch chain are simultaneously configured as drive pairs, and corresponding drive motors are respectively configured;

[0014] The motion modes supported by the reconfigurable motion platform include: three rotations and two movements and one rotation and two movements;

[0015] In the three-rotation-two-movement mode, the intersection of the three rotation pairs in the three branches and the rotation axis of the connecting rotation pair overlaps at one point;

[0016] In the one-rotation-two-movement mode, the intersection points of the rotation axes of the three rotation pairs in the three branch chains and the connecting rotation pairs do not intersect with each other.

[0017] The present application provides a two-mode parallel robot mechanism based on a reconfigurable moving platform, which adjusts the distance between the three V-shaped structures by using a moving pair on the moving platform, and controls whether the axes of the rotating shafts of the connecting rotating pairs intersect, thereby realizing the switching of the two motion modes of the reconfigurable moving platform: three rotations and two movements and one rotation and two movements; the present application can realize the reconstruction of the motion mode without changing the internal motion pairs of the branch chain, which reduces the complexity of the mode reconstruction, reduces the number of drive pairs in the branch chain, and thus reduces the moment of inertia during motion. The structures of the three branches of the present application are completely consistent and do not contain complex motion pairs, and the requirements for the stiffness and assembly accuracy of the mechanism components are relatively low. The overall structure is simple, easy to modularize and process and manufacture, and it can be applied to production and assembly tasks that require multiple motion modes. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0019] Figure 2 Schematic diagram of the structure of branch chain 1 of the present invention;

[0020] Figure 3 It is the general posture of the reconfigurable platform in the three-rotation and two-movement mode;

[0021] Figure 4 It is the general posture of the reconfigurable platform in one rotation and two movement modes.

[0022] Figure 5 This is the general posture of the mechanism of the present invention in the three-rotation and two-movement mode;

[0023] Figure 6 This is the general posture of the mechanism of the present invention in the one-rotation two-movement mode;

[0024] In the figure: 1 first branch chain; 11 first link of first branch chain; 12 second link of first branch chain; 13 third link of first branch chain; 14 fourth link of first branch chain; 2 second branch chain; 21 first link of second branch chain; 22 second link of second branch chain; 23 third link of second branch chain; 24 fourth link of second branch chain; 3 third branch chain; 31 first link of third branch chain; 32 second link of third branch chain; 33 third link of third branch chain; 34 fourth link of third branch chain; 4 reconfigurable braking platform; 41 first V-shaped structure; 411 first tubular side 1; 412 first tubular side 2; 42 second V-shaped structure; 421 second tubular side 1; 422 second tubular side 2; 43 third V-shaped structure; 431 third tubular side 1; 432 third tubular side 2;

[0025] 44 first moving platform connecting rod, 45 second moving platform connecting rod, 46 third moving platform connecting rod; 5 fixed base;

[0026] 1-1 first branch chain moving pair, 1-2 first rotational pair 1, 1-3 first rotational pair 2, 1-4 first rotational pair 3, 1-5 first connecting rotational pair;

[0027] 2-1 second branch chain moving pair, 2-2 second rotational pair 1, 2-3 second rotational pair 2, 2-4 second rotational pair 3, 2-5 second connecting rotational pair;

[0028] 3-1 the third branch chain moving pair, 3-2 the third rotation pair one, 3-3 the third rotation pair two, 3-4 the third rotation pair three, 3-5 the third connecting rotation pair. DETAILED DESCRIPTION

[0029] like Figures 1 to 6 As shown, the present application includes a two-mode parallel robot mechanism based on a reconfigurable moving platform, which includes: a fixed base 5 and a reconfigurable moving platform 4, and the fixed base 5 and the reconfigurable moving platform 4 are connected by a first branch chain 1, a second branch chain 2, and a third branch chain 3.

[0030] The reconfigurable dynamic platform 4 includes three V-shaped structures: a first V-shaped structure 41 , a second V-shaped structure 42 , and a third V-shaped structure 43 , and three dynamic platform connecting rods: a first dynamic platform connecting rod 44 , a second dynamic platform connecting rod 45 , and a third dynamic platform connecting rod 46 .

[0031] The V-shaped structure includes two tubular sides of equal length with an angle of 60°. The shape and size of the inner cavity of the tubular side are adapted to the outer diameter of the connecting rod for the movable platform. Each connecting rod for the movable platform is arranged between the two V-shaped structures. The two ends of each connecting rod for the movable platform are respectively inserted into a tubular side with a clearance fit to form a moving pair for the movable platform. The three V-shaped structures and the three connecting rods for the movable platform form an equilateral triangle.

[0032] Taking the first V-shaped structure 41 as an example, the first V-shaped structure 41 comprises two tubular sides of identical size and shape: a first tubular side 411 and a second tubular side 412. The inner cavity of the first tubular side 411 is adapted to the outer diameter of the second movable platform connecting rod 45, while the inner cavity of the second tubular side 412 is adapted to the outer diameter of the third movable platform connecting rod 46. In specific implementations, the shape of the movable platform connecting rod can be a round rod, a triangular rod, or a multi-sided rod, depending on specific needs.

[0033] The two ends of the second moving platform connecting rod 45 are respectively inserted into the inner cavities of the second tubular side 422 and the first tubular side 411, forming a moving pair for the moving platform. Similarly, the two ends of the first moving platform connecting rod 44 are respectively inserted into the inner cavities of the second tubular side 421 and the third tubular side 432, forming a moving pair for the moving platform; the two ends of the third moving platform connecting rod 46 are respectively inserted into the inner cavities of the third tubular side 431 and the first tubular side 412, forming a moving pair for the moving platform. In the reconfigurable moving platform 4, any one of the moving platform moving pairs can serve as a reconfigurable platform driving pair, controlling the configuration changes of the reconfigurable platform and thus completing the mode switching of the mechanism.

[0034] The first branch chain 1 is connected to a vertex of the reconfigurable mobile platform 4 through a first connecting rotation pair 1-5, the second branch chain 2 is connected to a second connecting rotation pair 2-5, and the third branch chain 3 is connected to a third connecting rotation pair 3-5.

[0035] The three branches have the same structure, comprising a first link, a second link, a third link, and a fourth link. One end of the first link is mounted on a fixed base 5 via a branch link moving pair. The other end of the first link is connected to one end of the second link, forming a revolute pair 1. The other end of the second link is connected to one end of the third link via a revolute pair 2. The other end of the third link is connected to one end of the fourth link via a revolute pair 3. The other end of the fourth link is connected to a vertex of the reconfigurable movable platform 4 via a connecting revolute pair. The branch link moving pair, revolute pair 1, and revolute pair 2 form a planar pair, with the rotational axes of revolute pairs 1 and 2 always parallel and perpendicular to the axis of motion of the branch link moving pair. The planar pair is then connected to revolute pair 3 and the connecting revolute pair, with the rotational axes of revolute pair 3 and the connecting revolute pair always intersecting at a point.

[0036] like Figure 2 As shown, the branch chain structure is described using the first branch chain 1 as an example. The branch chain structure includes: a first link 11, a second link 12, a third link 13, and a fourth link 14. One end of the first link 11 is mounted on the fixed base 5 via a first branch chain moving pair 1-1. The other end of the first link 11 is connected to one end of the second link 12 to form a first rotation pair 1-2. The other end of the second link 12 is connected to one end of the third link 13 via a first rotation pair 1-3. The other end of the third link 13 is connected to one end of the fourth link 14 via a first rotation pair 1-4. The other end of the fourth link 14 is connected to a vertex link of the reconfigurable mobile platform 4 via a first connecting rotation pair 1-5.

[0037] The three branches have the same structure, all PRR (RR) branches. P stands for translational pair, and R stands for rotational pair. The three rotational pairs in each branch, combined with the connecting rotational pair, form a spherical subchain (RR).

[0038] In the first branch chain 1, the first branch chain moving pair 1-1, the first rotation pair 1-2 and the first rotation pair 2 1-3 form a plane pair, and the rotation axes of the first rotation pair 1-2 and the first rotation pair 2 1-3 are always parallel and perpendicular to the movement axis of the first branch chain moving pair 1-1; the plane pair is connected to the first rotation pair 3 1-4 and the first connecting rotation pair 1-5; the first rotation pair 3 1-4 and the first connecting rotation pair 1-5 constitute a spherical sub-chain (RR), and the rotation axes of the two always intersect at one point.

[0039] The motion axes of the three branched movable pairs are located in the same plane. That is, in the first branch 1, the second branch 2, and the third branch 3, the motion axes of the three movable pairs mounted on the fixed base 5: the first movable pair 1-1, the second movable pair 2-1, and the third movable pair 3-1 are always located in the same plane.

[0040] The first moving pair 1-1 in the first branch chain 1, the second moving pair 2-1 in the second branch chain 2, the third moving pair 3-1 in the third branch chain 3, the first rotating pair 1-2 in the first branch chain 1, and the first rotating pair 1-4 in the first branch chain 1 are driving pairs, and corresponding driving motors are respectively provided.

[0041] The motion modes supported by the reconfigurable motion platform 4 include: three rotations and two movements 3T2R and one rotation and two movements 1T2R.

[0042] In the three-rotation and two-movement mode, the intersection of the rotation axis of the three rotation pairs in the three branches and the connecting rotation pair overlaps at one point;

[0043] In the one-rotation-two-movement mode, the intersection points of the rotational axes of the rotational pairs three in the three branch chains and the connecting rotational pairs do not intersect with each other.

[0044] Specifically, the intersection of the extended lines of the rotation axis of the rotation pair of each branch chain and the connecting rotation pair is located in the direction of the reconfigurable mobile platform 4. In the three-rotation two-movement mode, the intersection is located on the normal line passing through the plane of the reconfigurable mobile platform 4 and its geometric center point. Figure 3 and Figure 6 In the embodiment, the reconfigurable braking platform 4 is placed horizontally, and the intersection of each rotational pair 3 and the extended line of the rotation axis of the connecting rotational pair can be located above or below the reconfigurable braking platform 4. In this embodiment, the intersection of the rotation axis of the first rotational pair 3 1-4 and the first connecting rotational pair 1-5 is located below the reconfigurable braking platform 4.

[0045] At the same time, according to the angles between the rotation axes of the first connecting rotating pairs 1-5, the second connecting rotating pairs 2-5, and the third connecting rotating pairs 3-5 and the plane where the reconfigurable movable platform 4 is located, and the different positions of the intersections of the rotating pairs 3 and the rotation axes of the connecting rotating pairs, in actual implementation, the specific positions where the intersections of the rotating pairs 3 in the three branches overlap with the rotation axes of the connecting rotating pairs can be set according to specific circumstances. Figure 3 and Figure 5 In the embodiment shown, when the reconfigurable movable platform 4 is in the shortest state, the intersection of the rotational axis of the third rotational pair in the three branches and the connecting rotational pair overlaps at one point.

[0046] In this embodiment, when the first movable platform connecting rod 44, the second movable platform connecting rod 45, and the third movable platform connecting rod 46 are all completely retracted into the first V-shaped structure 41, the second V-shaped structure 42, and the third V-shaped structure 43, the reconfigurable movable platform 4 is in a state of an equilateral triangle with the smallest side length, the intersection of the first rotating pair 3 1-4 and the rotation axis of the first connecting rotating pair 1-5, the intersection of the second rotating pair 3 2-4 and the rotation axis of the second connecting rotating pair 2-5, and the intersection of the third rotating pair 3-4 and the rotation axis of the third connecting rotating pair 3-5, the three intersections overlap at point O.

[0047] Ensure that the three intersection points overlap at point O. The first moving pair 1-1 in the first branch chain 1, the second moving pair 2-1 in the second branch chain 2, the third moving pair 3-1 in the third branch chain 3, the first rotating pair 1-2 and the first rotating pair 1-4 in the first branch chain 1 serving as the driving pair are driven by corresponding driving motors to realize the three rotations and two movements of the reconfigurable dynamic platform 4.

[0048] In this embodiment, the platform movable pair where the first movable platform connecting rod 44 is located is configured as the driving pair of the movable platform. The driving structure causes the second tubular side 1 421 and the third tubular side 2 432 to be simultaneously driven at a uniform speed toward the midpoint of the side where the first movable platform connecting rod 44 is located, or simultaneously driven at a uniform speed toward the end points on both sides of the side where the first movable platform connecting rod 44 is located, thereby adjusting the length of the side where the first movable platform connecting rod 44 is located. Because the structures of the first V-shaped structure 41, the second V-shaped structure 42, and the third V-shaped structure 43 are fixed, when the length of the side where the first movable platform connecting rod 44 is located changes, the movable pairs where the second and third movable platform connecting rods 45, 46 are located will also change synchronously, achieving simultaneous and equal length changes in the lengths of the sides where the second and third movable platform connecting rods 45, 46 are located.

[0049] Therefore, in the three-rotation and two-movement mode, the driving structure causes the second tubular side 1 421 and the third tubular side 2 432 to be driven simultaneously toward the two end points of the side where the first moving platform connecting rod 44 is located at a uniform speed, thereby lengthening the side where the first moving platform connecting rod 44 is located. Figure 4 As shown, the second moving platform connecting rod 45 and the third moving platform connecting rod 46 are located in the moving pair, which will be lengthened synchronously, and then the intersection of the rotating pair of each branch chain and the rotating axis of the connecting rotating pair will be separated and will not intersect with each other, and the mechanism will enter the one rotation and two movement mode. Figure 6 As shown, the intersection of the rotation axis of the first rotating pair 3 1-4 and the first connecting rotating pair 1-5 is O1, the intersection of the rotation axis of the second rotating pair 3 2-4 and the second connecting rotating pair 2-5 is O2, and the intersection of the rotation axis of the third rotating pair 3-4 and the third connecting rotating pair 3-5 is O3. Points O1, O2 and O3 do not intersect each other.

[0050] Keeping points O1, O2 and O3 non-intersecting, the first moving pair 1-1 in the first branch 1, the second moving pair 2-1 in the second branch 2, the third moving pair 3-1 in the third branch 3, the first rotating pair 1-2 and the first rotating pair 1-4 in the first branch 1 as the driving pair are driven by corresponding driving motors to realize the one rotation and two movement movement of the reconfigurable dynamic platform 4.

[0051] After using the technical solution of the present invention, two different motion modes can be realized, namely three rotations and two movements and one rotation and two movements. The technical solution of this application has the advantages of simple structure, high precision, and easy control of mode switching. The structures of the three branches of this mechanism are completely consistent and do not contain complex motion pairs. It is easy to modularize and process and manufacture. It can be applied to production and assembly tasks that require multiple motion modes.

Claims

1. A two-mode parallel mechanism based on a reconfigurable dynamic platform, comprising: The fixed base and the reconfigurable braking platform are characterized in that: the fixed base and the reconfigurable braking platform are connected by a first branch chain, a second branch chain, and a third branch chain, and the three branch chains have the same structure, namely, PRRRR branches; The branch chain structure comprises: a branch chain moving pair, a rotating pair 1, a rotating pair 2, a rotating pair 3 and a connecting rotating pair connected in sequence; The reconfigurable dynamic platform includes: three V-shaped structures and three dynamic platform connecting rods. The V-shaped structure includes two equal-length tubular sides with an included angle of 60 degrees. The shape and size of the inner cavity of the tubular side are adapted to the outer diameter of the dynamic platform connecting rod. Each dynamic platform connecting rod is arranged between two V-shaped structures. The two ends of each dynamic platform connecting rod are respectively inserted into one of the tubular sides with a clearance fit to form a moving pair for the dynamic platform. The three V-shaped structures and the three dynamic platform connecting rods form an equilateral triangle. The first branch chain, the second branch chain and the third branch chain are respectively connected to a vertex of the reconfigurable dynamic platform through a connecting rotation pair; In the reconfigurable dynamic platform, any dynamic platform uses a moving pair as a reconfigurable platform driving pair to control the configuration change of the reconfigurable platform to complete the mode switching of the mechanism.

2. The two-mode parallel mechanism based on a reconfigurable dynamic platform according to claim 1, characterized in that: The branched chain structure includes: a first link, a second link, a third link, and a fourth link, one end of the first link is mounted on the fixed base via a branched chain movable pair, the other end of the first link is connected to one end of the second link to form a first revolving pair, the other end of the second link is connected to one end of the third link via a second revolving pair; the other end of the third link is connected to one end of the fourth link via a third revolving pair; the other end of the fourth link is connected to a vertex of the reconfigurable mobile platform via the connecting revolving pair; The branch chain moving pair, the rotating pair 1 and the rotating pair 2 form a plane pair, and the rotation axes of the rotating pair 1 and the rotating pair 2 are always parallel and perpendicular to the movement axis of the branch chain moving pair; the plane pair is connected to the rotating pair 3 and the connecting rotating pair, and the rotation axes of the rotating pair 3 and the connecting rotating pair always intersect at one point.

3. The two-mode parallel mechanism based on a reconfigurable dynamic platform according to claim 2, characterized in that: The motion axes of the three branch chain moving pairs are located in the same plane.

4. The two-mode parallel mechanism based on a reconfigurable dynamic platform according to claim 1, characterized in that: The branch moving pair of the first branch chain, the branch moving pair of the second branch chain, the branch moving pair of the third branch chain, the rotating pair 1 in the first branch chain, and the rotating pair 3 in the first branch chain are simultaneously set as driving pairs, and corresponding driving motors are respectively set.

5. The two-mode parallel mechanism based on a reconfigurable dynamic platform according to claim 2, characterized in that: The motion modes supported by the reconfigurable motion platform include: three rotations and two movements and one rotation and two movements; In the three-rotation-two-movement mode, the intersection of the three rotation pairs in the three branches and the rotation axis of the connecting rotation pair overlaps at one point; In the one-rotation-two-movement mode, the intersection points of the rotation axes of the rotation pairs three in the three branch chains and the connecting rotation pairs do not intersect with each other.

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