A PU type parallel robot mechanism without accompanying motion

Abstract

The application provides a PU type parallel robot mechanism without accompanying motion, three movement pairs are arranged to enable a moving platform to realize motion with one degree of freedom, three universal pairs are arranged to enable the moving platform to realize motion with two degrees of freedom, and the sliding of the corresponding universal pairs of the first supporting chain and the second supporting chain on the circular arc guide rail can avoid the accompanying motion of the mechanism, so that the parallel mechanism of the application avoids the occurrence of the accompanying motion, and the moving platform of the mechanism does not move unexpectedly after continuous rotation; because the occurrence of the accompanying motion is avoided, the PU type two-rotation-one-movement parallel mechanism of the application reduces the control difficulty and improves the motion precision of the moving platform.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of robot technology, in particular to a PU type parallel robot mechanism without accompanying motion. BACKGROUND

[0002] The two rotation directions of the PU type (two rotations and one translation) parallel mechanism are not affected by the mechanism translation motion, and the axes of the two rotation directions are located on the moving platform in the initial position and the single rotation position. Since the PU type parallel mechanism has good posture adjustment capability, it is widely used in ankle rehabilitation mechanisms, parallel power spindle heads and the like. The main disadvantage of the PU type parallel mechanism is that continuous rotation of part of the mechanism may cause unexpected translation motion, i.e. accompanying motion. The accompanying motion is an inherent property of the mechanism itself and cannot be eliminated by parameter optimization or compensated in real time by the robot control system, thus affecting the actual application scenarios of this type of mechanism. SUMMARY

[0003] In order to solve the problem of limited application scenarios caused by accompanying motion of the two rotations and one translation mechanism in the prior art, the present application provides a PU type parallel robot mechanism without accompanying motion, which does not produce unexpected translation motion, thus having higher motion accuracy and lower control difficulty, and can be adapted to more occasions with high precision requirements.

[0004] The technical solution of the present application is as follows: a PU type parallel robot mechanism without accompanying motion, comprising: a fixed platform, a moving platform and three structurally identical branch chains, the branch chains being arranged between the moving platform and the fixed platform;

[0005] characterized in that it further comprises: a circular arc guide rail, a universal joint and a driving joint seat;

[0006] The circular arc guide rail is arranged on the moving platform, and two of the circular arc guide rails are located on the circumference of the same circle and are symmetrically arranged based on the center of the circle.

[0007] The branch chain comprises: a branch chain link, one end of each branch chain link being connected to the moving platform through the universal joint, and the other end being connected to the driving joint seat through a rotation joint; and the driving joint seat being connected to the fixed platform based on a translation joint.

[0008] Two of the three universal joints are slidingly installed on one of the circular arc guide rails to form an arc translation joint, and the two branch chains are referred to as a first branch chain and a second branch chain; and the other branch chain is referred to as a third branch chain.

[0009] The third branch chain corresponds to the universal joint fixedly connected to the moving platform, and the connecting point of the universal joint of the third branch chain on the moving platform is on the line connecting the center of the circle of the circular arc guide rail and the center of the circle of the other circular arc guide rail, and the line is perpendicular to the line connecting the centers of the two circular arc guide rails.

[0010] The axes of the two moving pairs corresponding to the first branch chain and the second branch chain are on the same straight line, and the axis of the moving pair of the third branch chain is perpendicular to the axes of the other two moving pairs.

[0011] It is further characterized in that:

[0012] The three moving pairs are driving pairs;

[0013] The universal joint is connected to the branch chain connecting rod through rotating pair two and connected to the moving platform through rotating pair three, and the rotating shafts of the rotating pair two and the rotating pair three intersect and are perpendicular to each other;

[0014] One end of the branch chain connecting rod is provided with a U-shaped seat, and the other end is provided with a T-shaped structure; the universal joint comprises a cross structure and a connecting seat; one side of the cross structure and the connecting seat form the rotating pair three, and the other side and the U-shaped seat form the rotating pair two; the vertical edge of the T-shaped structure is connected to the branch chain connecting rod, and the horizontal edge and the driving pair seat form the rotating pair one;

[0015] The fixed platform is provided in a T-shaped frame structure, the vertical edge of the T-shaped frame is arranged at the center point of the horizontal edge and is perpendicular to the horizontal edge, and the driving pair seats of the first branch chain and the second branch chain respectively form the moving pairs with the horizontal edge;

[0016] The rotating shafts of the rotating pairs one of the first branch chain and the second branch chain are parallel to each other and are perpendicular to the rotating shaft of the rotating pair one of the third branch chain;

[0017] The connecting position of the universal joint and the moving platform comprises the bottom of the moving platform or the side wall of the moving platform.

[0018] The parallel mechanism provided in the application is a PU type parallel robot mechanism without accompanying motion, the arrangement of the three moving pairs can make the moving platform realize one degree of freedom motion, the three universal joints can make the moving platform realize two degrees of freedom motion, the sliding of the universal joints corresponding to the first branch chain and the second branch chain on the circular arc guide rail can avoid the occurrence of the accompanying motion of the mechanism, so that the parallel mechanism avoids the occurrence of the accompanying motion, and the mechanism shaft does not move unexpectedly after continuous rotation; because the occurrence of the accompanying motion is avoided, the PU type two-rotation-one-motion parallel mechanism improves the precision of the motion of the moving platform. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1It is a schematic diagram of the whole parallel robot mechanism structure without accompanying motion of the PU type of the present application;

[0020] Figure 2 It is a schematic diagram of the connecting structure of the universal joint and the moving platform;

[0021] Figure 3 It is an example diagram of the moving effect in the two-rotation-one-motion of the parallel mechanism of the present application;

[0022] Figure 4 It is an example diagram of the rotating effect in the two-rotation-one-motion of the parallel mechanism of the present application Figure 1 ;

[0023] Figure 5 It is an example diagram of the rotating effect in the two-rotation-one-motion of the parallel mechanism of the present application Figure 2 . DETAILED DESCRIPTION

[0024] As shown in Figures 1-5 , the present application comprises a PU type parallel robot mechanism without accompanying motion, which comprises a fixed platform 1, a moving platform 2, and a circular arc guide rail, a universal joint, a driving joint seat, and three structurally identical branch chains, which are arranged between the moving platform 2 and the fixed platform 1.

[0025] The circular arc guide rail is arranged on the moving platform 2, and two circular arc guide rails are located on the circumference of the same circle and are symmetrically arranged based on the center of the circle, that is, the connecting line of the center points of the two circular arc guide rails passes through the center of the circle. The connection position of the universal joint with the moving platform 2 includes the bottom of the moving platform 2 or the side wall of the moving platform 2. The circular arc guide rail can be arranged on the bottom of the moving platform 2, with the track downward, or on the side wall of the bottom of the moving platform 2, with the track outward; in this embodiment, both the first circular arc guide rail 15 and the second circular arc guide rail 25 are arranged on the bottom of the moving platform 2. The parallel mechanism in the present application has a simple structure and is more practical.

[0026] Two of the three universal joints are respectively slidingly connected to one circular arc guide rail, the circular arc guide rail limits the universal joint to perform arc line sliding with the center of the circular arc guide rail as the center, forming an arc line moving joint. The two branch chains connected with the circular arc guide rail are denoted as the first branch chain and the second branch chain, and the corresponding universal joints are denoted as the first universal joint and the second universal joint; the other branch chain is denoted as the third branch chain, and the corresponding universal joint is the third universal joint. The third universal joint is fixedly connected to the moving platform 2, and the connecting point of the third universal joint on the moving platform 2 and the center line of the circular arc guide rail pass through the center of the circle, which is perpendicular to the connecting line of the center points of the first circular arc guide rail 15 and the second circular arc guide rail 25 and intersects at the center.

[0027] The part of the PU type mechanism in the prior art is limited by the limited rotation angle of the spherical hinge, resulting in poor rotation ability of the moving platform of the mechanism, and the circular arc guide rail is arranged in the technical scheme of the application, the rotation range of the circular arc guide rail is large, the rotation ability of the moving platform during rotation of the mechanism is effectively improved, and compared with the existing spherical hinge structure, the machining difficulty is also greatly reduced.

[0028] The branched chain includes: branched chain connecting rods, one end of each branched chain connecting rod is connected to the moving platform 2 through a universal joint, and the other end is connected to the driving vice seat through a rotating joint; the driving vice seat is connected to the fixed platform 1 based on a moving joint; the axes of the two moving joints corresponding to the first branched chain and the second branched chain are located on the same straight line, and the axis of the moving joint of the third branched chain is perpendicular to the axes of the other two moving joints.

[0029] In this embodiment, the branched chain connecting rod of the first branched chain is the first branched chain connecting rod 12, and the first branched chain corresponds to the first driving vice seat 11; the branched chain connecting rod in the second branched chain is the second branched chain connecting rod 22, and the corresponding second driving vice seat 21; the branched chain connecting rod corresponding to the third branched chain is the third branched chain connecting rod 32, and the corresponding third driving vice seat 31. The fixed platform 1 is arranged as a T-shaped frame structure, the vertical edge of the T-shaped frame is arranged at the center point of the horizontal edge and is perpendicular to the horizontal edge, the first driving vice seat 11 and the horizontal edge of the fixed platform 1 constitute a first moving joint 101, the second driving vice seat 21 and the horizontal edge of the fixed platform 1 constitute a second moving joint 201, and the third driving vice seat 31 and the vertical edge of the fixed platform 1 constitute a third moving joint 301. The axes of the first moving joint 101 and the second moving joint 101 are on the same straight line and are perpendicular to the axis of the third moving joint 301.

[0030] Through the restriction of the horizontal edge of the fixed platform 1 and the two circular arc guide rails based on the center of symmetry, it is ensured that the first branched chain and the second branched chain are completely symmetrically arranged between the fixed platform and the moving platform.

[0031] One end of the branched chain connecting rod is arranged as a U-shaped seat, and the other end is arranged as a T-shaped structure. One end of the first branched chain connecting rod 12 is a first U-shaped seat 16, and the other end is a first T-shaped structure 17; one end of the second branched chain connecting rod 22 is a second U-shaped seat 26, and the other end is a second T-shaped structure 27; one end of the third branched chain connecting rod 32 is a third U-shaped seat 36, and the other end is a third T-shaped structure 37; the horizontal edge of the first T-shaped structure 17 and the first driving vice seat 11 constitute a first rotating joint 102, the second T-shaped structure 27 and the second driving vice seat 21 constitute a second rotating joint 202, and the third T-shaped structure 37 and the third driving vice seat 31 constitute a third rotating joint 302. The rotation axes of the first rotating joint 102 and the second rotating joint 202 are parallel to each other and are perpendicular to the rotation axis of the third rotating joint 302.

[0032] Each universal joint is connected with a branch chain connecting rod through rotating joint two, and is connected with the moving platform 2 through rotating joint three; and the rotating shafts of the rotating joint two and the rotating joint three intersect and are perpendicular to each other. In a specific implementation, the universal joint can be implemented based on the universal joint in the prior art.

[0033] In the embodiment, the universal joint comprises a cross structure and a connecting seat; the three universal joints are of the same structure, as shown in Figure 2 As shown in the figure, the structure of the universal joint is described by taking the first universal joint as an example. The first universal joint comprises a first cross structure 13 and a first connecting seat 14, and the first connecting seat 14 is slidingly installed in a first circular arc guide rail 15; the connecting seat is provided in a U-shaped structure, one side of the first cross structure 13 is inserted into the U-shaped mouth of the first connecting seat 14 at both ends, thereby constituting a first rotating joint three; the other side of the first cross structure 13 is inserted into a first U-shaped seat 16, thereby constituting a first rotating joint two with the first U-shaped seat 16, and the rotating shafts of the first rotating joint three and the first rotating joint two intersect and are perpendicular to each other. Similarly, a second connecting seat 24 is slidingly installed in a second circular arc guide rail 25, one side of a second cross structure 23 is inserted into the U-shaped mouth of the second connecting seat 24 at both ends, thereby constituting a second rotating joint three, and the other side of the second cross structure 23 constitutes a second rotating joint two with a second U-shaped seat 26; and a third connecting seat 34 is fixedly installed at the bottom of the moving platform 2, one side of a third cross structure 33 is inserted into the U-shaped mouth of the third connecting seat 34 at both ends, thereby constituting a third rotating joint three, and the other side of the third cross structure 33 constitutes a third rotating joint two with a third U-shaped seat 36.

[0034] In the embodiment, the first moving joint 101, the second moving joint 201 and the third moving joint 301 are set as driving joints and are driven by motors respectively, so as to ensure the realization of the two-rotation-one-movement of the moving platform; the remaining movement joints are follow-up joints and do not need to be driven by motors.

[0035] Based on the first moving joint 101, the second moving joint 201 and the third moving joint 301, the moving platform 2 can realize one degree of freedom of movement, and based on the first universal joint, the second universal joint and the third universal joint, the moving platform 2 can realize two degrees of freedom of rotation. The arc line sliding of the first universal joint on the first circular arc guide rail 15 and the arc line movement of the second universal joint on the second circular arc guide rail 25 can make the moving platform avoid the occurrence of accompanying movement in the movement, reduce the difficulty of control, and improve the accuracy of the movement of the moving platform.

[0036] Suppose Figure 1 is the initial state of the institution of the present application. Based on Figure 1The state in the figure, the motor will be started to move the first mobile vice 101 along the T-shaped fixed platform 1, the second mobile vice 201, the third mobile vice 301 to the center position of the T-shaped fixed platform 1 at the same time, with the movement of the three driving vices, the angles of the three first rotating vices 102, the second rotating vice 202 and the third rotating vice 302 change accordingly, if the three driving vices move to the center at the same speed, there will be no relative sliding between the first circular arc guide rail 15 and the second circular arc guide rail 25 and the universal joint connected with them, until to reach Figure 3 The position shown in the figure, the moving platform 2 realizes the movement in the vertical direction. Figures 3-5 The point O in the figure represents the center of motion of the moving platform.

[0037] Based on Figure 1 The state in the figure, the motor will be started to move the first mobile vice 101 along the T-shaped fixed platform 1, the second mobile vice 201, the third mobile vice 301 to the center position of the T-shaped fixed platform 1 at the same time, with the movement of the three driving vices, the angles of the three first rotating vices 102, the second rotating vice 202 and the third rotating vice 302 change accordingly, if the three driving vices move to the center at the same speed, there will be no relative sliding between the first circular arc guide rail 15 and the second circular arc guide rail 25 and the universal joint connected with them, until to reach Figure 4 The effect in the figure.

[0038] Based on Figure 4 The state in the figure, the motor will be started to move the first mobile vice 101 along the T-shaped fixed platform 1, the second mobile vice 201, the third mobile vice 301 to the center position of the T-shaped fixed platform 1 at the same time, with the movement of the three driving vices, the angles of the three first rotating vices 102, the second rotating vice 202 and the third rotating vice 302 change accordingly, if the three driving vices move to the center at the same speed, there will be no relative sliding between the first circular arc guide rail 15 and the second circular arc guide rail 25 and the universal joint connected with them, until to reach Figure 5 The effect in the figure.

[0039] In the embodiments of the application, the third driving sub-seat 31, the third branch chain connecting rod 32, the third cross structure 33, and the third connecting seat 34 are located in a vertical plane perpendicular to the plane of the fixed platform 1, denoted as a third branch chain plane, and the third driving sub-seat 31, the third branch chain connecting rod 32, the third cross structure 33, and the third connecting seat 34 can only move in the third branch chain plane; the first driving sub-seat 11, the first branch chain connecting rod 12, the first cross structure 13, and the first connecting seat 14 are located in a first branch chain plane, and these components can only move in the first branch chain plane; the second driving sub-seat 21, the second branch chain connecting rod 22, the second cross structure 23, and the second connecting seat 24 are located in a second branch chain plane, and these components can also only move in the second branch chain plane; the first branch chain plane and the second branch chain plane are the same plane, denoted as a first plane, and the first plane is also perpendicular to the plane of the fixed platform 1, so that the third branch chain plane is perpendicular to the first plane, and the intersection line of the two planes is the trajectory of the motion center of the movable platform; the intersection line is a vertical straight line perpendicular to the guide rail, so that the motion of the motion center of the movable platform has no other direction of movement, that is, there is no accompanying motion.

[0040] After the technical solution of the application is used, the PU-type two-rotation-one-translation parallel mechanism without accompanying motion does not produce movement other than the expected movement, so that the motion precision is higher, the control difficulty is lower, and it can be adapted to more occasions with high precision requirements, such as rehabilitation mechanisms, surgical robots, and the like. Meanwhile, the parallel mechanism in the application uses a moving pair as a driving pair, so that the driving is more stable and accurate.

Claims

1. A PU-type parallel robot mechanism with unaccompanied motion, comprising: A fixed platform, a movable platform, and three branches with the same structure, wherein the branches are arranged between the movable platform and the fixed platform; It is characterized in that it also includes: an arc guide rail, a universal joint and a driving joint seat; The arc guide rails are arranged on the movable platform, and the two arc guide rails are located on the circumference of the same circle and are symmetrically arranged based on the center of the circle; The branch chain includes: a branch link, one end of each branch link is connected to the moving platform via the universal joint, and the other end is connected to the driving sub-base via a rotating joint; the driving sub-base is connected to the fixed platform based on a moving joint; Two of the three universal joints are slidably mounted on one of the arc guide rails to form an arc moving pair. The two branches are denoted as the first branch and the second branch; the other branch is denoted as the third branch. The universal joint corresponding to the third branch chain is fixedly connected to the moving platform, and a line connecting the connection point of the universal joint of the third branch chain on the moving platform and the center of the circle where the circular arc guide rail is located is perpendicular to a line connecting the center points of the two circular arc guide rails; The axes of the two movable pairs corresponding to the first and second branches are located on the same straight line, and the axis of the movable pair of the third branch is perpendicular to the axes of the other two movable pairs; The three moving pairs are configured as driving pairs.

2. The PU-type parallel robot mechanism with unaccompanied motion according to claim 1, characterized in that: The universal joint is connected to the branch link through a second rotating joint, and is connected to the movable platform through a third rotating joint; and the rotation axes of the second rotating joint and the third rotating joint intersect and are perpendicular to each other.

3. The PU-type parallel robot mechanism with unaccompanied motion according to claim 2, characterized in that: A U-shaped seat is provided at one end of the branch link, and a T-structure is provided at the other end; the universal joint includes a cross structure and a connecting seat; one side of the cross structure and the connecting seat constitute the rotating pair three, and the other side and the U-shaped seat constitute the rotating pair two; the vertical side of the T-structure is connected to the branch link, and the horizontal side and the driving pair seat constitute the rotating pair one.

4. The PU-type parallel robot mechanism with unaccompanied motion according to claim 1, characterized in that: The fixed platform is configured as a T-frame structure, wherein the vertical side of the T-frame is configured at the center point of the horizontal side and is perpendicular to the horizontal side, and the driving sub-seats of the first branch chain and the second branch chain respectively form the moving sub-seats with the horizontal side.

5. The PU-type parallel robot mechanism with unaccompanied motion according to claim 1, characterized in that: The rotation axes of the first rotational pair of the first branch chain and the second branch chain are parallel to each other and perpendicular to the rotation axis of the first rotational pair of the third branch chain.

6. The PU-type parallel robot mechanism with unaccompanied motion according to claim 1, characterized in that: The connection position between the universal joint and the moving platform includes: the bottom of the moving platform or the side wall of the moving platform.

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