CN102689304B - Three-freedom-degree mobile parallel robot mechanism - Google Patents

Abstract

The invention relates to a three-degree-of-freedom mobile parallel robot mechanism, which includes a moving platform and a fixed platform. Three branch kinematic chains with the same structure and orthogonal distribution in space are arranged between the moving and fixed platforms. , each branch kinematic chain is composed of the first moving pair, the first rotating pair, the second rotating pair, the parallelogram structure and the kinematic pair in series, and the moving directions of the three first moving pairs corresponding to the three branched kinematic chains are perpendicular to each other , and have a spatially orthogonal distribution. The mechanism can be used as an end effector of industrial robots, medical robots and micro-manipulation robots. The mechanism has simple structure, good kinematics decoupling and high motion performance.

Description

A three-degree-of-freedom mobile parallel robot mechanism

technical field

The invention relates to the field of industrial robots, in particular to a non-overconstrained fully decoupled three-degree-of-freedom parallel robot mechanism.

Background technique

The parallel robot mechanism is generally composed of a moving platform, a fixed platform and several branches (generally 2~6). Compared with the traditional serial mechanism, the parallel robot mechanism has the advantages of strong load capacity, high precision, high stiffness, fast speed response and small self-weight-to-load ratio. Parallel robotic mechanism has become a research hotspot in the field of mechanism and robotics in the past two decades.

For the general parallel robot mechanism, its kinematic coupling is very strong, one motion output of the moving platform often needs multiple input control, and the kinematic solution is complicated, such as the famous 6-DOF Steward parallel mechanism, the kinematics of this mechanism There are 40 groups of solutions; another example is the 3-DOF mobile Delta parallel mechanism, which consists of 12 ball pairs, 3 revolving pairs and 14 rods, and has 16 groups of kinematic solutions with a relatively complex structure. Tsai L-W designed a new type of three-dimensional mobile parallel mechanism based on the Delta mechanism (US Patent, No. 5656905, published on August 12, 1997). Although the structure is relatively simple compared with the former, its kinematic solution is eight times. The stronger the kinematic coupling of the parallel robot mechanism, the more the number of kinematic solutions, the smaller the working space relative to the volume of the mechanism, and the more difficult the trajectory planning and precision control of the mechanism. Kong X-W designed a 3-CRR parallel mechanism, which consists of only 3 cylindrical pairs, 6 rotating pairs and 6 rods. The structure is relatively simple, but the angle theory between the axis of the rotating pair and the cylindrical pair and the normal line of the moving platform plane The value is 54.7356 degrees, which puts forward higher requirements for the processing and assembly of related parts.

Domestic scholars have also made a series of achievements in the research of three-dimensional mobile parallel mechanisms, such as a "three-translation space parallel robot mechanism" disclosed in Chinese patent 201010225496.4. Although the structure of this mechanism is relatively simple, it has strong kinematic coupling. Therefore, designing a parallel mechanism with simple structure, good kinematic decoupling and high kinematic performance has become a new research topic in this field.

Contents of the invention

The purpose of the present invention is to provide a non-overconstrained fully decoupled three-degree-of-freedom parallel robot mechanism to solve the problems of limited decoupling and complex structure of the parallel robot mechanism in the prior art.

In order to solve the above problems, the technical solution of the present invention is:

A three-degree-of-freedom mobile parallel robot mechanism, including a moving platform and a fixed platform. Three branch kinematic chains with the same structure and orthogonal distribution in space are arranged between the moving and fixed platforms. Between the fixed platform and the moving platform , each branch kinematic chain is composed of the first moving pair, the first rotating pair, the second rotating pair, the parallelogram structure and the kinematic pair in series. Between the first moving pair and the first rotating pair, the second rotating pair The pair and the kinematic pair are respectively connected by the second member and the third member. The parallelogram structure and the kinematic pair are composed of the following two forms: the first form, the parallelogram structure includes four axes parallel to each other The first, second, third, and fourth connecting members connected between the quadrilateral revolving pairs and the four quadrilateral revolving pairs, the axes of each of the quadrilateral revolving pairs, the first revolving pairs, and the second revolving pairs are all aligned with the corresponding first moving The moving directions of the pairs are parallel to each other, the second rotating pair is installed in the middle of the first connecting member, and the third connecting member in the parallelogram structure is installed on the moving platform through the moving pair In the above, the kinematic pair is composed of a rotating pair whose axis coincides with the center line of the third connecting member; in the second form, the parallelogram structure is surrounded by the first, second, and fourth connecting members and a moving platform, The second and fourth connecting members are arranged parallel to each other on the two ends of the first connecting member through corresponding quadrilateral rotating pairs, and the axes of the quadrangular rotating pairs, the first rotating pair and the second rotating pair are parallel to the moving direction of the corresponding first moving pair, the second rotating pair is installed in the middle of the first connecting member, and the other ends of the second and fourth connecting members pass through the corresponding moving pair and the moving platform respectively. connected, the kinematic pair is a universal joint or a spherical joint;

The moving directions of the three first moving pairs corresponding to the three branched kinematic chains are perpendicular to each other and distributed in a spatially orthogonal manner.

The moving platform is a regular hexagon with opposite sides parallel and non-adjacent sides having the same length, and the three kinematic pairs corresponding to each branch kinematic chain are respectively arranged on the non-adjacent sides of the moving platform.

The moving platform is provided with three guide rails with three guiding directions distributed orthogonally in space, and the three first moving pairs corresponding to each branch kinematic chain are respectively assembled on the corresponding three guide rails.

The three-degree-of-freedom mobile parallel robot mechanism also includes a linear motor or a ball screw drive mechanism driven by a servo motor that is respectively connected to the corresponding first moving pair to drive each first moving pair to move linearly along the corresponding guide rail.

The beneficial effects of the present invention are: the three branched kinematic chains are respectively the first, second and third branched kinematic chains, and the moving directions of the first moving pair corresponding to the three branched kinematic chains are respectively the X direction and the Y direction which are perpendicular to each other in the space and Z direction, when the moving platform needs to reciprocate along the X direction, the moving platform can be driven by driving the first moving pair of the first branch kinematic chain to move along the X direction, during which, the first 2. The third branch kinematic chain performs adaptive movement; when the moving platform needs to reciprocate along the Y direction, the moving platform can be driven by driving the second moving pair of the second branch kinematic chain to move along the Y direction, where During the process, the first and third branch kinematic chains do adaptive motion; when the moving platform is required to reciprocate along the Z direction of the track, it can be achieved by driving the third moving pair of the third branch kinematic chain to move along the Z direction. The moving platform is driven, and in the process, the first and second branch kinematic chains perform adaptive motion; finally, the non-over-constrained and completely decoupled three-degree-of-freedom mobile parallel robot mechanism of the present invention is realized. The kinematics and mechanical properties of the parallel robot mechanism are the same in any direction in the entire working space, and the one-to-one control relationship between the motion input and output of the mechanism can be realized, that is, one motion output of the moving platform only needs one driver to control. The kinematic decoupling of the existing robot mechanism is poor, and one output of the mechanism's dynamic platform requires multiple input controls.

Description of drawings

Fig. 1 is the structural representation of embodiment 1 of the present invention;

Fig. 2 is the structural representation of embodiment 2 of the present invention;

Fig. 3 is a schematic structural diagram of Embodiment 3 of the present invention.

Detailed ways

An embodiment 1 of a three-degree-of-freedom mobile parallel robot mechanism is shown in Figure 1: it includes a fixed platform 10, a moving platform 20, and three kinematic chains that connect the fixed platform 10 and the moving platform 20 with the same structure and are orthogonal in space. The moving platform 10 adopts a regular hexagonal structure with opposite sides parallel and non-adjacent sides equal in length. The three branch kinematic chains are the first branch kinematic chain L1 , the second branch kinematic chain L2 and the third branch kinematic chain L3 .

The three directions perpendicular to each other in the space are respectively defined as X direction, Y direction and Z direction, and the fixed platform 10 is provided with X guide rails 1-1 and Y guide rails respectively extending along the X direction, Y direction and Z direction. 1-2 and Z guide rail 1-3, the first branch kinematic chain L1 is set corresponding to X guide rail 1-1, the second branch kinematic chain L2 is set corresponding to Y guide rail 1-2, and the third branch kinematic chain L3 is set corresponding to Z guide rails 1-3 should be set correspondingly. The three branched kinematic chains have exactly the same structural form, and each branched kinematic chain is sequentially connected in series by the first moving pair P1, the first rotating pair R1, the second rotating pair R2, the parallelogram structure Pa and the moving pair R3; The quadrilateral structure Pa consists of four quadrilateral rotating pairs parallel to the axes and the first connecting member 4a, the second connecting member 4b, the third connecting member 4d and the fourth connecting member 4c connected between the four quadrangular rotating pairs, four The quadrilateral revolving pair and four connecting members form a closed loop, and the four quadrilateral revolving pairs are respectively the first quadrilateral revolving pair Ra1, the second quadrilateral revolving pair Ra2, the third quadrilateral revolving pair Ra3 and the fourth quadrilateral Revolving pair Ra4, the moving direction of the first moving pair P1 is parallel to the axes of the corresponding first rotating pair R1, the second rotating pair R2 and the four quadrilateral rotating pairs in the parallelogram structure, and is perpendicular to the axis of the moving pair R3; Between the first moving pair P1 and the first rotating pair R1, between the first rotating pair R1 and the second rotating pair R2 are connected through the second member 2 and the third member 3; the second rotating pair is installed in the middle of the member 4a point position; the parallelogram linkage mechanism is installed on the moving platform through the kinematic pair R3, the kinematic pair R3 is composed of a rotating pair whose axis coincides with the centerline of the third connecting member 4d, and the kinematic pair R3 is directly fixed on the moving platform 20; three The axis of the first moving pair P1 of the branch kinematic chain is distributed orthogonally in space, that is, the X direction 1-1, the Y guide rail 1-2 and the Z guide rail 1-3 are perpendicular to each other; the first moving pair P1 of each branch kinematic chain is The active pair, whose output mode is linear, is used to control the movement of the braking platform along the direction of its own slideway; the drive device is connected to the reducer at the power output end of the servo motor, and the reducer is connected to the ball screw mechanism by transmission, and the ball screw The form in which the lever mechanism is connected with the corresponding mobile pair transmission. (or servo motor + ball screw structure, or linear motor, or linear slide).

The non-overconstrained fully decoupled three-degree-of-freedom mobile parallel robot mechanism of the present invention can be used to drive the first branch kinematic chain L1 when the moving platform needs to reciprocate along the X-guiding rail 1-1 during the work project. The first moving pair P1 drives the moving platform 20, and in the process, the second and third branch kinematic chains perform adaptive motion; when the moving platform is required to reciprocate along the Y guide rail 1-2, The moving platform 20 can be driven by driving the second moving pair of the second branch kinematic chain L2, and in the process, the first and third branch kinematic chains perform adaptive motion; when the moving platform 20 is required When reciprocating along the Z guide rail 1-3, the moving platform 20 can be driven by driving the third moving pair of the third branch kinematic chain L3. In the process, the first and second branch kinematic chains Do adaptive motion; finally realize the non-over-constrained fully decoupled three-degree-of-freedom mobile parallel robot mechanism of the present invention. Since the Jacobian matrix of the mechanism is a unit matrix, the value of its condition number and determinant is always equal to 1, so the kinematics of the mechanism is not only completely decoupled, but also has completely isotropic performance, that is, the mechanism moves along any direction in the entire working space The kinematics and mechanical properties are the same; the motion input and output of this mechanism can realize a one-to-one control relationship, that is, one motion output of the moving platform 20 only needs to be controlled by one driver, which solves the kinematic solution of the existing robot mechanism Poor coupling, the problem that one output of the moving platform of the mechanism requires multiple input controls; in addition, the existence of the kinematic pair R3 in each branch not only makes the mechanism change from an over-constrained mechanism to a non-over-constrained mechanism, but more importantly, makes each branch The assembly relationship between the kinematic chain and the moving platform 20 is greatly simplified. The invention relates to a three-dimensional mobile terminal actuator that can be used in the fields of industrial robots, medical robots, micro-manipulation robots, virtual machine tools and the like.

An embodiment 2 of a three-degree-of-freedom mobile parallel robot mechanism is shown in Figure 2: the difference between embodiment 2 and embodiment 1 is that the parallelogram structure is composed of the first quadrilateral revolving pair Ra1, the second quadrilateral It is surrounded by the shape rotating pair Ra2, the first universal hinge U1, the second universal hinge U2, and the first connecting member 4a, the second connecting member 4b, the fourth connecting member 4c and the moving platform 20, the parallelogram No. The two and four connecting members are arranged on the two ends of the first connecting member 4a parallel to each other through the corresponding first quadrilateral rotating pair Ra1 and the second quadrilateral rotating pair Ra2, each of the quadrilateral rotating pairs, The axes of the first rotating pair R1 and the second rotating pair R2 are parallel to the moving direction of the corresponding first moving pair P1, and the second rotating pair R2 is installed at the midpoint of the first connecting member 4a, so The other ends of the second and fourth connecting members are installed on the moving platform 20 through the first universal hinge U1 and the second universal hinge U2 respectively. The first universal hinge U1 has a first rotation axis U1-1 parallel to the moving direction of the corresponding first moving pair P1 and a second rotation axis U1-2 parallel to the centerline of the first connecting member 4a; The second universal joint U2 has a first rotation axis U2-1 parallel to the moving direction of the corresponding first moving pair P1 and a second rotation axis U2-2 parallel to the centerline of the first connecting member 4a.

Embodiment 3 of a three-degree-of-freedom mobile parallel robot mechanism is shown in Figure 3: the difference between Embodiment 3 and Embodiment 2 is that the first universal joint U1 connected between the second connecting member 4b and the moving platform 20 Transform into the first ball joint S1 and the second universal joint U2 connected between the fourth connecting member 4c and the moving platform 20 into the second ball joint S2.

Claims (4)

1. a three free degree moving parallel connected robot mechanism, comprise moving platform and fixed platform, it is characterized in that: described is dynamic, identical and the sub-chain that the is distribution in orthogonal space of three version is provided with between fixed platform, between fixed platform to moving platform, each sub-chain is by the first moving sets, first revolute pair, second revolute pair, parallelogram sturcutre and kinematic pair sequential series form, between described first moving sets and the first revolute pair, be connected with the 3rd component by second component respectively between first revolute pair and the second revolute pair, described parallelogram sturcutre and kinematic pair are by following two kinds of forms: the first form, described parallelogram sturcutre comprises quadrangle revolute pair that four axis are parallel to each other and is connected to first between four quadrangle revolute pairs, two, three, four connecting elements, described each quadrangle revolute pair, first revolute pair, the axis of the second revolute pair is all parallel to each other with the moving direction of corresponding first moving sets, the second described revolute pair is arranged on the middle part of described first connecting elements, the 3rd connecting elements in described parallelogram sturcutre is arranged on described moving platform by described kinematic pair, the revolute pair that described kinematic pair is overlapped with the center line of described 3rd connecting elements by axis is formed, described kinematic pair is directly fixed on moving platform, the second form, described parallelogram sturcutre is by first, two, four connecting elements and moving platform surround, described second, the two ends being arranged at described first connecting elements that four connecting elements are parallel to each other respectively by the quadrangle revolute pair of correspondence, described each quadrangle revolute pair, first revolute pair, the axis of the second revolute pair is all parallel to each other with the moving direction of corresponding first moving sets, the second described revolute pair is arranged on the middle part of described first connecting elements, described second, the other end of four connecting elements is connected with moving platform respectively by corresponding sports pair, described kinematic pair is universal hinge or ball pivot,

The moving direction of three the first moving sets that described three sub-chains are corresponding is mutually vertical, and the distribution in orthogonal space.

2. three free degree moving parallel connected robot mechanism according to claim 1, it is characterized in that: described moving platform is that opposite side is parallel and the regular hexagonal that non-conterminous edge lengths is equal, and three kinematic pairs that described each sub-chain is corresponding are arranged on the non-conterminous limit of described moving platform respectively.

3. three free degree moving parallel connected robot mechanism according to claim 1, it is characterized in that: described moving platform is provided with three guide rails that three guide direction are orthogonal space distribution, three the first moving sets that described each sub-chain is corresponding are assemblied on three corresponding guide rails respectively.

4. three free degree moving parallel connected robot mechanism according to claim 3, is characterized in that: described three free degree moving parallel connected robot mechanism also comprises and is in transmission connection with corresponding first moving sets respectively to drive each first moving sets along the linear electric motors of corresponding guide rail rectilinear motion or the ball-screw transmission mechanism by driven by servomotor.