Two-rotation-one-movement asymmetric fully decoupled parallel robot

Abstract

The present invention provides a two-rotation and one-movement asymmetric fully decoupled parallel robot, comprising a static platform, a moving platform and three branch kinematic chains. In the present invention, when the first rotating pair in the first branch kinematic chain is inputted as an active pair alone, the moving platform has one rotational degree of freedom, when the second moving pair in the second branch kinematic chain is inputted as an active pair alone, the moving platform has another rotational degree of freedom, and when the linear displacement of the first cylindrical pair in the third branch kinematic chain and the first rotating pair in the first branch kinematic chain are simultaneously inputted as active pairs, and the displacement of the first universal joint in the vertical direction is the same as the displacement of the first cylindrical pair, the moving platform has one degree of freedom of movement. Thus, the present invention has three degrees of freedom, namely, rotation in two directions and movement in one direction, is simple to control, and has strong practicality. It solves the problems of strong coupling of ordinary parallel mechanisms, complex kinematic calculations, and difficult path planning, and has broad application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of industrial robots, and in particular to a two-rotation-one-movement asymmetric fully decoupled parallel robot. Background Art

[0002] The parallel mechanism is composed of a moving platform and a fixed platform connected by multiple branch kinematic chains. Compared with the series mechanism, it has the advantages of compact structure, high rigidity, and strong load-bearing capacity. It has been widely used in many fields such as medical instruments, aerospace, and motion simulators.

[0003] Compared with the 6-DOF parallel mechanism, the low-DOF parallel mechanism has the advantages of fewer driving parts, fewer components, easy control, easy manufacturing, and low cost. In particular, the parallel mechanism with two rotations and one movement and three degrees of freedom has become a hot topic in this field due to its broad application prospects. At present, some scholars in my country have made certain research progress in the two-rotation-one-movement three-DOF parallel mechanism, but most of the existing parallel robot mechanisms have problems such as strong motion coupling, small working space, complex control, and poor motion accuracy. Summary of the invention

[0004] The purpose of the present invention is to provide a two-rotation and one-movement asymmetric fully decoupled parallel robot to solve the problems of strong kinematic coupling, poor decoupling and small working space of the parallel mechanism existing in the prior art.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: an asymmetric fully decoupled parallel mechanism with two rotations and one movement, including a fixed platform, a moving platform and three branch kinematic chains, a connecting column is arranged on one side of the top of the fixed platform, and the three branch kinematic chains are respectively a first branch kinematic chain, a second branch kinematic chain and a third branch kinematic chain, wherein:

[0006] The first branch kinematic chain comprises a first rotating pair, a first universal joint, a first moving pair and a second universal joint which are sequentially connected by a connecting rod, the free ends of the first rotating pair and the second universal joint are respectively connected to the connecting column and the moving platform, the axis of the first rotating pair is parallel to the inner axis of the first universal joint, the outer axis of the first universal joint is parallel to the inner axis of the second universal joint and is perpendicular to the moving direction of the first moving pair;

[0007] The second branch kinematic chain includes a second moving pair, a second rotating pair, a third moving pair and a ball pair which are sequentially connected by a connecting rod, free ends of the second moving pair and the ball pair are respectively connected to the fixed platform and the moving platform, and the axis of the second rotating pair is perpendicular to the moving direction of the third moving pair;

[0008] The third branch kinematic chain includes a first cylindrical pair and a third rotation pair connected by a connecting rod, the free ends of the first cylindrical pair and the third rotation pair are respectively connected to the fixed platform and the movable platform, and the axes of the first cylindrical pair and the third rotation pair are located in the same plane and are arranged perpendicular to each other;

[0009] The first rotating pair, the first cylindrical pair and the second moving pair are all power input ends and are respectively connected to drive motors.

[0010] Furthermore, the axis of the second rotating pair, the axis of the third rotating pair and the outer axis of the second universal joint are arranged in parallel.

[0011] Furthermore, a circular arc track matching with the second moving pair is provided on the fixed platform, and the axis of the first cylindrical pair is perpendicular to the plane where the circular arc track is located and passes through the center of the circular arc track.

[0012] Furthermore, the third revolving pair is located at the center of the moving platform, and the second universal joint, the third revolving pair and the ball joint are sequentially arranged along the length direction of the moving platform and are distributed on the same straight line.

[0013] Furthermore, two ends of the first universal joint are connected to the first rotating pair and the first moving pair through a first connecting rod and a second connecting rod respectively, and the free end of the first moving pair is connected to the second universal joint through a third connecting rod.

[0014] Furthermore, two ends of the second rotating pair are connected to the second moving pair and the third moving pair through a fourth connecting rod and a fifth connecting rod respectively, and a free end of the third moving pair is connected to the ball pair through a sixth connecting rod.

[0015] Furthermore, the first cylindrical pair and the third rotation pair are connected via a seventh connecting rod.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: in the present invention, when the first rotating pair in the first branch motion chain is inputted as an active pair alone, the movable platform has one rotational degree of freedom; when the second moving pair in the second branch motion chain is inputted as an active pair alone, the movable platform has another rotational degree of freedom; when the linear displacement of the first cylindrical pair in the third branch motion chain and the first rotating pair in the first branch motion chain are simultaneously inputted as active pairs, and the displacement of the first universal joint in the vertical direction is the same as the displacement of the first cylindrical pair, the movable platform has one degree of freedom of movement. Thus, the present invention has three degrees of freedom, namely, rotation in two directions and movement in one direction. At this time, the velocity Jacobian matrix of the mechanism is a diagonal matrix, which has completely decoupled kinematic characteristics, and is simple to control and highly practical. It solves the problems of strong coupling of ordinary parallel mechanisms, complex kinematic calculations, and difficult path planning, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the asymmetric fully decoupled parallel mechanism with two rotations and one movement according to the present invention;

[0018] Figure 2 This is a schematic diagram of the distribution of the second universal joint, ball joint and third revolute joint on the moving platform. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0020] like Figure 1 As shown, the two-rotation-one-movement asymmetric fully decoupled parallel robot of the present invention comprises a fixed platform 10 and a moving platform 20, and L1, L2, and L3 represent the first, second, and third branch kinematic chains respectively.

[0021] The first branch kinematic chain L1 includes a first rotating pair R11, a first universal joint U12, a first moving pair P13 and a second universal joint U14. One end of the first rotating pair R11 and the second universal joint U14 are directly connected to the fixed platform 10 and the moving platform 20 respectively. A connecting column for connecting the first rotating pair R11 is provided on one side of the top of the fixed platform. The first universal joint U12 is connected to the first rotating pair R11 and the first moving pair P13 through the first connecting rod 1-1 and the second connecting rod 1-2 respectively. The first moving pair P13 is connected to the second universal joint U14 through the third connecting rod 1-3. Among them, the axis of the first rotating pair R11 is parallel to the axis connected to the first connecting rod 1-1 in the first universal joint U12, that is, the inner axis, the axis connected to the second connecting rod 1-2 in the first universal joint U12, that is, the outer axis, and the axis connected to the third connecting rod 1-3 in the second universal joint U14, that is, the inner axis, and the outer axis of the first universal joint U12 is perpendicular to the moving direction of the first moving pair P13.

[0022] The second branch kinematic chain L2 includes a second mobile pair P21, a second rotation pair R22, a third mobile pair P23 and a ball pair S24. The second mobile pair P21 and the ball pair S24 are directly connected to the fixed platform 10 and the moving platform 20 respectively, the second rotation pair R22 is connected to the second mobile pair P21 and the third mobile pair P23 through the fourth connecting rod 2-1 and the fifth connecting rod 2-2 respectively, and the third mobile pair P23 is connected to the ball pair S24 through the sixth connecting rod 2-3. Among them, the axis of the second rotation pair R22 is perpendicular to the moving direction of the third mobile pair P23.

[0023] The third branch kinematic chain L3 includes a first cylindrical pair C31 and a third rotation pair R32. One end of the first cylindrical pair C31 and one end of the third rotation pair R32 are directly connected to the fixed platform 10 and the moving platform 20 respectively, and the third rotation pair R32 is connected to the first cylindrical pair C31 through the seventh connecting rod 3-1. Among them, the axis of the first cylindrical pair C31 and the axis of the third rotation pair R32 are in the same plane and perpendicular to each other.

[0024] In this embodiment, the axis of the second rotation pair R22 in the second branch motion chain L2, the axis of the third rotation pair R32 in the third branch motion chain L3 and the axis of the universal joint U13 connected to the moving platform 20, i.e., the outer axis, are parallel to each other.

[0025] To further optimize this solution, the axis of the first universal joint U12 in the first branch kinematic chain L1 connected to the second link 1-2 is parallel to the axis of the first cylindrical pair C31 in the third branch kinematic chain L3, and is perpendicular to the axis of the third rotation pair R32 in the third branch kinematic chain L3. The second moving pair P21 of the second branch kinematic chain L2 moves along the circular track, and the axis of the first cylindrical pair C31 in the third branch kinematic chain L3 is perpendicular to the plane of the circular track and passes through the center of the circular track.

[0026] To further optimize this solution, Figure 2 As shown, the second universal joint U14 in the first branch motion chain L1 and the ball joint S24 in the second branch motion chain L2 are on both sides of the moving platform 20, the third rotation joint R32 in the third branch motion chain L3 is located at the center of the moving platform 20, and the three are distributed on the same straight line.

[0027] In the parallel mechanism, the kinematic pairs connected to the fixed platform 10 in the three branch kinematic chains are respectively selected as active pairs, wherein the first cylindrical pair C31 in the third branch kinematic chain L3 uses linear displacement as active input.

[0028] The control principle of the present invention is as follows: the present invention drives the active pair through a servo motor and provides power to the moving platform 20 through three branch motion chains. The first drive motor drives the first rotation pair R11 in the first branch motion chain L1, so that the moving platform 20 rotates around the axis direction of the third rotation pair R32 in the third branch motion chain L3; the second drive motor drives the second movement pair P21 in the second branch motion chain L2, so that the moving platform 20 rotates around the axis direction of the first cylindrical pair C31 in the third branch motion chain L3; the first drive motor and the third drive motor respectively drive the first rotation pair R11 in the first branch motion chain L1 and the first cylindrical pair C31 in the third branch motion chain L3, so that the moving platform 20 moves along the axis direction of the first cylindrical pair C31 in the third branch motion chain L3, thereby realizing the parallel mechanism with two rotations and one movement in space. Three degrees of freedom.

[0029] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A two-rotation and one-movement asymmetric fully decoupled parallel robot, comprising a fixed platform, a moving platform and three branch kinematic chains, wherein a connecting column is arranged on one side of the top of the fixed platform, and characterized in that: The three branch kinematic chains are the first branch kinematic chain, the second branch kinematic chain and the third branch kinematic chain, where: The first branch kinematic chain comprises a first rotating pair, a first universal joint, a first moving pair and a second universal joint which are sequentially connected by a connecting rod, the free ends of the first rotating pair and the second universal joint are respectively connected to the connecting column and the moving platform, the axis of the first rotating pair is parallel to the inner axis of the first universal joint, the outer axis of the first universal joint is parallel to the inner axis of the second universal joint and is perpendicular to the moving direction of the first moving pair; The second branch kinematic chain includes a second moving pair, a second rotating pair, a third moving pair and a ball pair which are sequentially connected by a connecting rod, free ends of the second moving pair and the ball pair are respectively connected to the fixed platform and the moving platform, and the axis of the second rotating pair is perpendicular to the moving direction of the third moving pair; The third branch kinematic chain includes a first cylindrical pair and a third rotation pair connected by a connecting rod, the free ends of the first cylindrical pair and the third rotation pair are respectively connected to the fixed platform and the movable platform, and the axes of the first cylindrical pair and the third rotation pair are located in the same plane and are arranged perpendicular to each other; The first rotating pair, the first cylindrical pair and the second moving pair are all power input ends and are respectively connected to drive motors; the axis of the second rotating pair, the axis of the third rotating pair and the outer axis of the second universal joint are arranged in parallel; a circular arc track matching the second moving pair is opened on the fixed platform, and the axis of the first cylindrical pair is perpendicular to the plane where the circular arc track is located and passes through the center of the circular arc track; the third rotating pair is located at the center of the moving platform, and the second universal joint, the third rotating pair and the ball pair are arranged in sequence along the length direction of the moving platform and the three are distributed on the same straight line; the two ends of the first universal joint are respectively connected to the first rotating pair and the first moving pair through the first connecting rod and the second connecting rod, and the free end of the first moving pair is connected to the second universal joint through the third connecting rod.

2. The two-rotation-one-movement asymmetric fully decoupled parallel robot according to claim 1, characterized in that: The two ends of the second rotational pair are connected to the second movable pair and the third movable pair through a fourth connecting rod and a fifth connecting rod respectively, and the free end of the third movable pair is connected to the ball pair through a sixth connecting rod.

3. The two-rotation-one-movement asymmetric fully decoupled parallel robot according to claim 1, characterized in that: The first cylindrical pair and the third rotation pair are connected via a seventh connecting rod.

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