CN114603329B - 3PRS-3RRR double-platform device for intelligent assembly - Google Patents
3PRS-3RRR double-platform device for intelligent assembly Download PDFInfo
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Abstract
The application discloses a 3PRS-3RRR dual-platform device for intelligent assembly, include: an upper platform, comprising: a plurality of first branches, each of the first branches being a P-R-S pair connection; the P-R-S pair comprises: a moving pair P pair, a first revolute pair R pair and a ball pair S pair, wherein the first revolute pair R pair is arranged on the moving pair P pair, and the ball pair S pair is arranged on the first revolute pair R pair; the tail ends of a plurality of first branched chains are arranged on the same tail end connecting piece; a lower platform, comprising: a plurality of second branches, each of which comprises a plurality of second revolute pair R pairs connected in series; wherein the upper platform is mounted on the lower platform. The upper platform and the lower platform have multiple degrees of freedom, space assembly tasks which can be completed by the multiple degrees of freedom can be executed with high precision and high efficiency, and a large number of simple assembly tasks need to be repeatedly executed with high precision in the actual production process.
Description
Technical Field
The application belongs to the technical field of automation and robots, and particularly relates to 3PRS-3RRR double-platform equipment for intelligent assembly.
Background
The automatic assembly is an important technology in the manufacturing industry, and in order to improve the assembly efficiency in the industrial production process, reduce the assembly error, and simultaneously improve the automation level of the manufacturing industry, an automatic intelligent assembly device with high precision and high speed is designed. The existing assembly equipment is not intelligent, is difficult to work with intelligent sensors such as vision and force sense, and meanwhile, the stability of the equipment is poor. In addition, most existing motion work platforms do not have the characteristics of high precision and rapidity, and the task requirement of precise assembly is difficult to complete.
Disclosure of Invention
In view of the foregoing drawbacks or shortcomings of the prior art, the technical problem to be solved by the present application is to provide a 3PRS-3RRR dual platform device for intelligent assembly.
In order to solve the technical problems, the application is realized by the following technical scheme:
the application provides a 3PRS-3RRR dual-platform device for intelligent assembly, comprising:
an upper platform, comprising: a plurality of first branches, each of the first branches being a P-R-S pair connection; the P-R-S pair comprises: a moving pair P pair, a first revolute pair R pair and a ball pair S pair, wherein the first revolute pair R pair is arranged on the moving pair P pair, and the ball pair S pair is arranged on the first revolute pair R pair; the tail ends of a plurality of first branched chains are arranged on the same tail end connecting piece;
a lower platform, comprising: a plurality of second branches, each of which comprises a plurality of second revolute pair R pairs connected in series;
wherein the upper platform is mounted on the lower platform.
Optionally, the 3PRS-3RRR dual platform device for intelligent assembly, wherein the mobile pair P pair includes: the device comprises a first driving motor, a coupler, a first guide rail, a ball screw and a first sliding block, wherein the first driving motor is connected with the ball screw arranged on the first guide rail through the coupler and drives the ball screw to rotate and drive the first sliding block on the ball screw to move up and down, and the first sliding block is arranged on the ball screw.
Optionally, the 3PRS-3RRR dual platform device for intelligent assembly described above, wherein the first revolute pair R pair is mounted on the first slider.
Optionally, the 3PRS-3RRR dual platform device for intelligent assembly described above, wherein the ball pair S pair comprises: and the first equivalent S pair, the second equivalent S pair and the third equivalent S pair are formed by intersecting a plurality of rotation axes at one point, wherein the first equivalent S pair, the second equivalent S pair and the third equivalent S pair are all arranged on the revolute pair R pair.
Optionally, the 3PRS-3RRR dual platform device for intelligent assembly described above, wherein the end connector is further provided with a six-dimensional force and moment sensor for detecting a contact force and a contact moment.
Optionally, the 3PRS-3RRR dual platform device for intelligent assembly described above, wherein the second revolute pair R pair comprises: the device comprises a first R pair, a second R pair and a third R pair, wherein the first R pair is rotatably arranged on a second rack, the first R pair transmits rotary motion through an inner connecting rod, the inner connecting rod is connected with an outer connecting rod through the second R pair, and the outer connecting rod is rotatably connected with a bearing platform through the third R pair.
Optionally, the 3PRS-3RRR dual platform device for intelligent assembly described above, wherein the lower platform further comprises: the first R pairs are arranged on the rotating shaft supporting seat; and/or, further comprising: a second driving motor for driving a plurality of the first R pairs to rotate; and/or, further comprising: the support frame is used for installing the second driving motor.
Optionally, the 3PRS-3RRR dual platform device for intelligent assembly described above, wherein the rotation axes of a plurality of the first R pairs are arranged in a coincident manner.
Optionally, in the 3PRS-3RRR dual platform device for intelligent assembly, the number of the first branches is three, and the upper platform includes: a 3PRS mechanism having one degree of freedom of movement in a vertical direction and two degrees of freedom of rotation in a plane, i.e., three degrees of freedom; the number of the second branched chains is three, and the lower platform comprises: a 3RRR mechanism having lateral movement, longitudinal movement, and rotation about a vertical direction, i.e., three degrees of freedom; the dual platform device has six degrees of freedom.
Optionally, the 3PRS-3RRR dual platform device for intelligent assembly described above, wherein the upper platform is connected to a box through a first rack, and the box is mounted on the lower platform;
and/or the lower platform is arranged on the electrical cabinet through a second rack;
and/or a first driving controller, a first cooling fan and a first sensor main board are arranged in the box body;
and/or a second driving controller, a second cooling fan and a second sensor main board are arranged in the electrical cabinet;
and/or the electrical cabinet is in a packaging box body form, and the side surface of the electrical cabinet is also provided with an external interface, an emergency stop switch, a status display lamp, a power supply and a control switch.
Compared with the prior art, the application has the following technical effects:
the upper platform and the lower platform have multiple degrees of freedom, space assembly tasks which can be completed by the multiple degrees of freedom can be executed with high precision and high efficiency, and in the actual production process, a large number of simple assembly tasks need to be repeatedly executed with high precision, such as the procedures of memory bank mounting, bolt tightening and the like in the common 3C industry, and the assembly of a mouse receiver and a battery and the like can be executed through the application; the method has the advantages of high degree of freedom, high precision, high speed, flexible movement, capability of repeatedly executing assembly actions and the like.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the detailed description of non-limiting embodiments, made with reference to the following drawings, in which:
fig. 1: the embodiment of the application is used for the perspective view of the intelligent assembled 3PRS-3RRR double-platform device;
fig. 2: in an embodiment of the present application, the upper platform is schematically configured;
fig. 3: in an embodiment of the present application, a schematic structural diagram of a lower platform;
fig. 4: a motion diagram of a 3PRS mechanism in an embodiment of the present application;
fig. 5: a simplified diagram of a 3PRS mechanism in an embodiment of the present application;
fig. 6: a schematic diagram of a 3PRS mechanism in an embodiment of the present application;
fig. 7: a motion schematic of the 3RRR mechanism in an embodiment of the present application;
fig. 8: a schematic of a 3RRR mechanism in an embodiment of the present application;
fig. 9: a schematic diagram of a 3RRR mechanism in an embodiment of the present application;
fig. 10: the embodiment of the application is used for a motion schematic diagram of the intelligent assembly 3PRS-3RRR double-platform device.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
As shown in fig. 1 to 3, in one embodiment of the present application, a 3PRS-3RRR dual platform device for intelligent assembly includes:
upper platform 1, comprising: the first branched chains are connected by a P-R-S pair (P: a moving pair; R: a rotating pair; S: a ball pair); the P-R-S pair comprises: a moving pair P, a first revolute pair R15 and a ball pair S, wherein the first revolute pair R15 is mounted on the moving pair P and the ball pair S is mounted on the first revolute pair R15; the ends of a plurality of the first branches are mounted on the same end connector 110;
a lower platform 2 comprising: a plurality of second branches, each of which comprises a plurality of second revolute pair R pairs connected in series; a bearing platform 21 is also arranged on the lower platform 2;
wherein the upper platform 1 is mounted on the lower platform 2.
The upper platform 1 and the lower platform 2 of the embodiment have multiple degrees of freedom, can perform space assembly tasks which can be completed by requiring multiple degrees of freedom with high precision and high efficiency, and in the actual production process, a large number of simple assembly tasks need to be repeatedly performed with high precision, for example, the common procedures of memory card assembly, bolt tightening and the like in the 3C industry, and the mouse receiver and battery assembly and the like can all perform the assembly tasks through the embodiment; the embodiment also has the advantages of high degree of freedom, high precision, high speed, flexible movement, capability of repeatedly executing assembly actions and the like.
Further, the upper platform 1 has three degrees of freedom of movement, including up and down movement, rotation around the lateral direction, and rotation around the longitudinal direction, and the lower platform 2 has three degrees of freedom of movement, including lateral movement, longitudinal movement, and rotation around the vertical direction. In this embodiment, the upper stage 1 has three degrees of freedom, and the lower stage 2 has three degrees of freedom for illustration.
In a specific application, the assembly object and the workpiece can be placed on the bearing platform 21, and the female assembly is fixedly assembled by using a certain fixture. By means of the lateral, longitudinal movement and rotation about the vertical direction of the lower platform 2, the assembly position and the picking position can be positioned with a high degree of accuracy.
In this embodiment, as shown in fig. 2, the pair of moving pairs P includes: the first driving motor 11 is connected with the ball screw arranged on the first guide rail 13 through the coupler 12 and drives the ball screw to rotate and drive the first slider 14 on the ball screw to move up and down, and the first slider 14 is arranged on the ball screw. The moving pair P is an active pair, and the corresponding first driving motor 11 is connected with the ball screw installed on the first guide rail 13 through the coupling 12, so as to drive the ball screw to rotate and drive the first slider 14 on the ball screw to move up and down. The three first branched chains are symmetrically distributed and completely consistent in structure, the driving pairs of the three first branched chains are P pairs, the driving pairs are driven by the corresponding three motors, and rotary motion is converted into linear motion through the ball screw.
Alternatively, the first slider 14 is preferably a slider nut.
The revolute pair R pair 15 is mounted on the first slider 14. Wherein, the revolute pair R pair 15 is a passive pair.
The ball pair S pair comprises: a first equivalent S pair 16, a second equivalent S pair 17, and a third equivalent S pair 18, each of which is formed by intersecting a plurality of rotation axes at a single point, wherein the first equivalent S pair 16, the second equivalent S pair 17, and the third equivalent S pair 18 are mounted on the revolute pair R pair. Wherein, the ball pair S pair is a passive pair.
It is also noted that the ball pair S pair is not a conventional complete independent S pair. Specifically, when the rotation axes of the three revolute pairs intersect at one point, both the motion performance and the calculation manner thereof are considered to be equivalent to those of the S pair in the mechanics, and thus are called equivalent spherical hinge pairs (S pairs).
The ends of the first branches are mounted on the same end connector 110, and further, the ends of the first equivalent S pair 16, the second equivalent S pair 17 and the third equivalent S pair 18 are commonly mounted on the same end connector 110.
Further, to improve accuracy and efficiency in the assembly process and to improve fault tolerance in the assembly process, six-dimensional force and moment sensors 111 for detecting contact force and contact moment are further installed on the end connector 110, so that the assembly process is fed back and controlled in real time by the detected force in the assembly process. Meanwhile, the auxiliary visual positioning can be carried out on the upper platform 1 by matching with visual equipment, so that the automatic assembly level is further improved.
Optionally, a specific end effector is mounted below the six-dimensional force and moment sensor 111 as required by a particular assembly task. Since the upper platform 1 can move up and down and has a rotation around the lateral direction and a rotation around the longitudinal direction, the upper platform 1 can be controlled so that the end effector grips and seats the assembled part.
In this embodiment, as shown in fig. 1, the upper platform 1 is connected to the box 3 through a first frame 19, and the box 3 is mounted on the lower platform 2. Further, optionally, a first driving controller, a first cooling fan and a first sensor motherboard are installed in the case 3.
As shown in fig. 3, the second revolute pair R pair includes: the first R pair 27, the second R pair and the third R pair, wherein the first R pair 27 is rotatably mounted on the second rack 28, the first R pair 27 transmits rotary motion through the inner connecting rod 24, the inner connecting rod 24 is connected with the outer connecting rod 22 through the second R pair, and the outer connecting rod 22 is rotatably connected with the bearing platform 21 through the third R pair. Wherein the first R pair 27 is an active pair, and the second R pair and the third R pair are passive pairs.
Further preferably, in the present embodiment, the second revolute pair R pairs are preferably provided with three, wherein each of the second revolute pair R pairs is driven by a second driving motor 25 provided separately and corresponding thereto. It is further preferred that the second drive motor 25 is used for driving the first R pair 27, wherein the first drive motor is further provided with a second drive belt 26 matching thereto.
The second R pair includes, but is not limited to: the connecting shaft 23 is described above by way of example only.
Further, the lower platform further comprises: the rotating shaft supporting seat 29, a plurality of the first R pairs 27 are installed on the rotating shaft supporting seat 29, and the rotating shaft supporting seat 29 mainly plays a role of installation and supporting. Further preferably, in this embodiment, three first R pairs 27 (driving pairs) are disposed, the rotation axes of the three first R pairs 27 are disposed in a overlapping manner, and the three driving pairs are driven by their corresponding second driving motors 25 independently.
The lower platform 2 further comprises: a support frame 210, wherein the support frame 210 is used for installing the second driving motor 25.
In this embodiment, three second driving motors 25 are symmetrically distributed at 120 ° and three corresponding supporting frames 210 are correspondingly designed. Of course, the supporting frame 210 may also be configured as an integrally formed structure.
Further, in this embodiment, the lower platform 2 is mounted on the electrical cabinet 4 through the second rack 28, and the second driving controller, the second cooling fan and the second sensor motherboard are mounted in the electrical cabinet 4.
Further alternatively, the electrical cabinet 4 is in the form of a packaging box 3, and the side surface of the electrical cabinet is also provided with an external interface, a scram switch, a status display lamp and a power supply and control switch.
In performing the assembly task, the positioning of the assembled workpiece and the assembled master may be measured and positioned according to the determined fixed position, or a visual positioning device may be used. The six-degree-of-freedom double-motion platform supports carrying of an industrial vision camera for positioning and workpiece detection, so that the assembly process is more intelligent.
Further preferably, the number of the first branches is three, and the upper platform 1 includes: a 3PRS mechanism having one degree of freedom of movement in a vertical direction and two degrees of freedom of rotation in a plane, i.e., three degrees of freedom; the number of the second branched chains is three, and the lower platform 2 includes: a 3RRR mechanism having lateral movement, longitudinal movement, and rotation about a vertical direction, i.e., three degrees of freedom; the dual-platform device has complete six degrees of freedom in space.
Specifically, the upper platform 1 has three degrees of freedom of movement, namely up-and-down movement, rotation around the transverse direction and rotation around the longitudinal direction, and the three degrees of freedom of movement are realized through a 3-PRS mechanism, namely, branched chains formed by three P-R-S pairs are connected in parallel. In each first branched chain, the moving pair P pair is an active pair, and is driven by a corresponding first driving motor 11, the first driving motor 11 drives the ball screw to rotate, and the first sliding block 14 mounted on the ball screw moves linearly, so that the P pair is formed. A corresponding pair of rotation pairs R15 is designed on the outer side of each screw nut by a bearing or the like. The first equivalent S pair 16, the second equivalent S pair 17, and the third equivalent S pair 18 intersecting at one point through three rotation axes under the rotation pair R pair 15 constitute one equivalent spherical hinge pair S pair. The three first branched end S pairs are connected in parallel to a common end connector 110.
The lower platform 2 has three degrees of freedom of movement, namely lateral movement, longitudinal movement and rotation around the vertical direction, and the three degrees of freedom of movement are realized through a 3-RRR mechanism, namely branched chains formed by three R-R-R pairs are connected in parallel. The first R pairs 27 of the three second branches are all driving pairs, and the rotation axes of the three driving pairs are coincident. The second driving motor 25 and the second driving belt 26 drive three rotating shafts, and the axes of the three rotating shafts are located at the first R pair 27. The three revolute pairs on each second branched chain are respectively positioned at the second driving motor 25 and the first R pair 27 of the driving shaft driven by the belt transmission, the connecting rod shaft 23 where the inner connecting rod 24 is connected with the outer connecting rod 22, and the connecting position where the outer connecting rod 22 is connected with the bearing platform 21.
The PRS-3RRR dual platform of this example 3 is used for the specific implementation of the assembly process:
the assembly parent component and the to-be-assembled component are fixed on the bearing platform 21 of the lower platform 2, and the three second driving motors 25 of the lower platform 2 are controlled to drive the bearing platform 21 to move in three dimensions of transverse movement, longitudinal movement, rotation around the vertical direction and the like, so that the to-be-assembled component is positioned and oriented to the end effector of the upper platform.
The three first driving motors 11 of the upper platform 1 can be controlled to drive the end effector of the upper platform 1 to move up and down, rotate around the transverse axis and rotate around the longitudinal axis, so that the posture and the position of the end effector can be further adjusted, and the end effector can conveniently take and put the parts to be assembled.
The three first driving motors 11 of the upper platform 1 and the three second driving motors 25 of the lower platform 2 are cooperatively controlled to load the fitting to be fitted into the fitting female by the determined positional and posture relationship.
During this assembly, the force and moment generated upon contact can be measured using the six-dimensional force and force sensor 111, thereby performing feedback control of the movement process. Meanwhile, the magnitude of the force and moment detected by the sensor 111 can also be used to determine whether the assembly process is completed.
Note that the end effector may be modified and replaced accordingly under different assembly tasks. For example, motorized jaws may be used as end effectors during memory stick assembly. An alternative solution is to use a sleeve with strong magnetism inside, corresponding to the type of the bolt.
When the assembly task is performed, positioning of the assembly to be assembled and the assembly master can be performed according to the determined fixed position, and visual positioning equipment can also be used. The six-degree-of-freedom double-motion platform supports carrying of an industrial vision camera for positioning and workpiece detection, so that the assembly process is more intelligent.
The control process of the present embodiment will be described in detail below.
Wherein, for 3PRS kinematics:
as shown in fig. 4 to 6, the 3PRS mechanism has one vertical movement degree of freedom and two in-plane rotation degrees of freedom, and its schematic diagram is shown in fig. 6, and the mechanism is composed of 3 branches, each of which is composed of a pair of moving pairs P, a pair of rotating pairs R15, and a pair of ball pairs S. Establishing a base coordinate system O as shown in the following diagram u -xyz and establishing an end follow-up coordinate system O 'on an end platform' u -x′y′z′。
Set the end platform in a fixed coordinate system O u Pose at-xyz
The pose is expressed in terms of ZYZ euler angles. The 3PRS mechanism has three independent degrees of freedom, which can be represented by z, phi and theta, and the terminal pose has six parameters, so that the terminal pose parameters are not independent of each other, and the other three parameters have relevance to z, phi and theta. The freedom degree property of the 3PRS shows that the mechanism can only move along the vertical direction, and no other freedom degrees exist in the movement, so that the displacement of the tail end pose in the x and y directions is always 0. To determine the parameter->
Correlations with known parameters phi, theta, assuming terminal platforms at +.>
The rotation matrix in the posture is R, and the S pairs of the tail end ball pairs are distributed on a circle with the radius R
Center coordinate a of S-pair i in base coordinate system i The method can be expressed as follows:
a i ＝p+Ra i ′ (2)
wherein p= [ x y z ]] T ，
a′ 2 ＝[0 r 0] T
The terminal parameter is dependent on the configuration of the mechanism, and the configuration arrangement is easy to know that the 3 branched chain connecting rod can only rotate around the branched chain revolute pair R pair 15, so that the ball pair S pair at the terminal of the connecting rod can only move in a determined plane perpendicular to the rotating shaft of the revolute pair R pair 15. From the above geometrical properties, the correlation between spherical hinge coordinates can be obtained as shown in the following formula:
solving and simplifying the joint formulas (1), (2) and (3) to obtain the relationship among the parameters as follows:
the rotation matrix R expressed by the ZYZ euler angle is:
combining (4) with (5)Parameters (parameters)
The correlations with the known parameters phi, theta are:
the end pose of 3PRS can be represented by x= [ X y z phi theta-phi ] by combining the above analysis.
From fig. 6, a vector closed loop equation for each branch can be constructed:
p+a i ＝c i +q i e i +l i (i＝1,2,3) (7)
wherein a is i ＝Ra i 'R is the terminal pose conversion matrix, a' i iS the position of the iS-th secondary center in the end follow-up coordinate system.
After shifting the left and right elements in formula (7), letting N i ＝p+a i -c i The following formula can be obtained:
l i ＝N i -q i e i (8)
the square post-finishing is obtained by taking both sides of the equation (8):
in equation (9), when the end pose is given, other parameters except qi are known, so the equation is a unitary quadratic equation, and the equation can be obtained by solving the equation by using the unitary quadratic equation:
there are two solutions to the equation, corresponding to the physical meaning that when an end pose is given, there are two different sets of drive input solutions. The value of the sign may be confirmed given the initial state of the institution. The sign can be ensured not to be changed without exceeding the singular point in the movement process of the mechanism. Under the configuration arrangement and coordinate system shown in fig. 6, the initial pose x= [0 0 0 0 0 0] is brought into the negative sign of the solution of the equation available in (10), i.e
So far, a unique driving input solution corresponding to any end pose of the mechanism is obtained through calculation of the geometric relationship, and the equation (11) is the inverse kinematics solution of the 3-PRS mechanism.
Wherein, for 3RRR kinematics:
as shown in fig. 7 to 9, the 3-RRR mechanism is a planar motion mechanism having one degree of freedom of rotation about the vertical direction and two degrees of freedom of movement in the plane, and its schematic diagram is shown in fig. 9 (for convenience of description, three coaxial driving pairs (first R pair 27) are separately drawn as C i ) The mechanism consists of 3 second branched chains, and each second branched chain consists of three revolute pairs. Establishing a plane-based coordinate system O shown in the following diagram d Xy and establishing an end plane follow-up coordinate system O 'on the end platform' d -x′y′。
Set the end platform in the base coordinate system O d The pose under-xy is x= [ X y θ ]]The circular radius of the tail end platform formed by three uniformly distributed revolute pairs is a, the circular radius of the base formed by three uniformly distributed revolute pairs is b, and the rotation angles of the driving input are respectively
Then the terminal plane follows the coordinate system O' d -A under x' y i The coordinates of (2) are:
plane base coordinate system O d -xy lower C i 、B i And A is a i The coordinates of (2) are:
according to the geometrical relationship of the mechanism, knowing that each second branched chain meets the requirement of |A i B i |＝|L 2 The following relation can be obtained:
wherein, each parameter has the following meaning, x, y, θ, a, b are known amounts:
D 3 ＝x-asinθ
simplifying (13) each item to obtain
Is a solution expression of (2):
from (14), it is known that the 3-RRR mechanism has two solutions for each second branch input under a certain pose, and the two solutions are correspondingly distributed in A in the upper graph i C i The two sides of the connecting line are determined according to the initial position of the connecting rod when the value is solved.
So far, a unique driving input solution corresponding to any end pose of the mechanism is obtained through calculation of the geometric relationship, and equation (14) is the inverse kinematics solution of the 3-RRR mechanism.
As shown in fig. 10, the kinematic working principle of the PRS-3RRR system of this embodiment 3 is as follows:
establishing an upper platform 1 base coordinate system O on a 3-PRS operating device u -xyz and upper stage 1 dynamic coordinate system O' u -x ' y ' z ', establishing a local base coordinate system O on a 3-RRR work platform d -xyz and lower stage 2 dynamic coordinate system O' d -x ' y ' z ', wherein O u -xyz and O d -xyz has a z-axis coaxial, x being parallel and coplanar with the y-axis, and in an initial state, the coordinate system O d -xyz and O' d -x ' y ' z ' are fully coincident. O (O) B XYZ is the global base coordinate system of the combined platform, which is built on the end platform of the lower platform 2 and moves along with the movement of the end platform of the 3-RRR mechanism, and is connected with O 'in the initial state' u -x ' y ' z ' coincide.
The whole working platform has 6 degrees of freedom, and the combined up-and-down motion can form a full-degree-of-freedom mechanism with the degrees of freedom of position and posture. The working platform has 6 inputs, namely 3 moving inputs of the upper platform 1 and 3 rotating inputs of the lower platform 2, which are respectively set as
According to the theory of mechanics, the number of the input and the number of the output degrees of freedom of the working platform are the same, and the control of all the outputs can be realized. To construct the relative motion relationship between the upper and lower platforms 2, a coordinate system O moving along with the terminal platform of the 3-RRR mechanism is taken B XYZ is used as the base coordinate system of the working platform, the local coordinate system O 'on the end platform of the upper platform 1' u -x ' y ' z ' is used as a dynamic coordinate system for the work platform, and the relative motion relationship between the upper and lower end platforms is solved under the coordinate specification.
The problem of position inverse solution of the mechanism combination can be converted into the problem of distribution of the end pose. Set up end platform in coordinate system O B The pose under XYZ can be expressed as x= [ X y z αβγ] T Corresponding homogeneous transformation matrix B T u′ And (3) representing. Similarly, a terminal motion coordinate system O 'of the upper platform 1 is set' u -x ' y ' z ' in a coordinate system O u Pose at-xyz is expressed as u T u′ Lower platform 2 terminal motion coordinate system O' d -x ' y ' z ' in a coordinate system O d Pose at-xyz is expressed as d T d′ Coordinate system O u -xyz-coordinate system O d Homogeneous transformation matrix of-xyz as d T u ，O′ d -x ' y ' z ' coordinate system to global base coordinate system O B Homogeneous transformation matrix of XYZ B T d′ The pose of the tail end of the upper platform 1 is in the global basic coordinate system O B The representation under XYZ can be calculated from the following formula:
B T u′ ＝ B T d′ [ d T d′ ] -1d T u u T u′ (15)
for the convenience of representation and visual understanding of the terminal gesture, the terminal gesture is represented by using an Euler angle method which sequentially rotates around a space coordinate axis XYZ. Because the plane corner can only be realized by the upper platform 1, and the pose of the upper platform 1 is coupled with the position of the upper platform 1, six-dimensional space output of the upper platform 1 is determined according to the output required to be realized by the upper platform 1, and then the rest position and the pose are realized by the lower platform 2, and meanwhile, the lower platform 2 compensates the accompanying motion quantity generated by the upper platform 1. The specific pose distribution process is as follows:
(1) The lower stage 2 is coaxial with the upper stage 1 in the z-axis of both the base coordinate systems in the initial state, and the lower stage 2 can rotate only about the z-axis direction. If the upper platform 1 is represented by Euler angles which rotate around the Z axis, and the pose [ alpha beta gamma ]]The same Euler angle is adopted to express, so that the pose [ alpha beta gamma ] can be conveniently expressed by utilizing the z-axis coaxial relation of the upper platform and the lower platform in the initial state]The part to be realized by the lower platform 2 is allocated to the lower platform 2. The upper platform 1 is arranged in a coordinate system O u Pose at-xyz is expressed as ZYZ euler angle
To unify the representation method, pose [ alpha beta gamma ]]Conversion to the ZYZ Euler angle is denoted +.>
The pose can be expressed as +.>
(2) The upper platform 1 is associated with motion solving. Pose (pose)
Middle position z, second euler angle θ and third euler angle +.>
Can be uniquely realized by the upper platform 1, namely z u ＝z、θ u ＝θ、/>
But due to constraint relation the upper platform 1 generates a wrap O u Concomitant motion phi of z-axis rotation of an xyz coordinate system u Displacement x u And y is u . The displacement part in the accompanying motion needs to be converted into a base coordinate system O B In XYZ to facilitate displacement compensation of the lower platform 2. Let O be d -xyz to O B The rotation matrix of XYZ is B R u Then the concomitant displacement is expressed as +.>
(3) And solving the motion component of the lower platform 2. Let the lower platform 2 be in the coordinate system O d Pose at-xyz is [ x ] d y d φ d ] T The rotation angle phi d ＝φ-φ u . Set up a coordinate system O B -XYZ to coordinate System O d -xyz rotation matrix is d R B The displacement of the lower platform 2 can be expressed as
Pose transformation d R B And B R u expressed as [ -phi ] by ZYZ Euler angle d -π 0] T And [ -phi ] d 0 0] T 。
(4) And solving the inverse kinematics solution of the upper platform 1 and the lower platform 2. Through the above solution analysis, the pose X= [ X y z alpha beta gamma] T The input of the upper platform and the lower platform can be obtained by decomposing the pose output of the upper platform and the lower platform and the inverse solution of the kinematics of the original mechanism.
So far, when the pose of the upper end platform relative to the lower end platform is given through the distribution of the position and the pose, the 6 input quantities of the upper and lower platforms are obtained, and at the moment, clear coordinated movement of the upper and lower platforms can be realized by controlling the driving motors corresponding to the six input quantities.
The upper platform and the lower platform have multiple degrees of freedom, space assembly tasks which can be completed by the multiple degrees of freedom can be executed with high precision and high efficiency, and in the actual production process, a large number of simple assembly tasks need to be repeatedly executed with high precision, such as the procedures of memory bank mounting, bolt tightening and the like in the common 3C industry, and the assembly of a mouse receiver and a battery and the like can be executed through the application; the method has the advantages of high degree of freedom, high precision, high speed, flexible movement, capability of repeatedly executing assembly actions and the like. In the present application, alternatively, the upper platform has three degrees of freedom of one movement and two rotations, and the lower platform has three degrees of freedom of lateral and longitudinal movement and rotation about a vertical axis, so the apparatus as a whole has six degrees of freedom; the end effector for assembly can be arranged on the upper platform and the lower platform, and can be provided with intelligent sensors such as force sense, vision and the like, so that intelligent assembly with high precision and high efficiency is realized; in addition, the five-degree-of-freedom motion platform can be matched with a vision and force sensor for use, and automatic positioning and force control assembly are realized. When the assembly tool is particularly applied, the assembly object and the workpiece can be placed on the bearing platform, and the female assembly is fixedly assembled by utilizing a certain tool. By means of the lateral and longitudinal movement of the lower platform and rotation about the vertical axis, the assembly position and the picking position can be positioned with a high degree of accuracy.
In the description of the present application, unless explicitly stated and limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.
In this application, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, and may also include the first and second features not being in direct contact but being in contact with each other by way of additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.
In the description of the present embodiment, the terms "upper", "lower", "left", "right", etc. azimuth or positional relationship are based on the azimuth or positional relationship shown in the drawings, and are merely for convenience of description and simplification of operations, and do not indicate or imply that the apparatus or element referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like, are used merely for distinguishing between descriptions and not for distinguishing between them.
The above embodiments are only for illustrating the technical solution of the present application, not for limiting, and the present application is described in detail with reference to the preferred embodiments. It will be understood by those skilled in the art that various modifications and equivalent substitutions may be made to the technical solution of the present application without departing from the spirit and scope of the technical solution of the present application, and it is intended to cover within the scope of the claims of the present application.
Claims (9)
1. A 3PRS-3RRR dual platform device for intelligent assembly, comprising:
an upper platform, comprising: a plurality of first branches, each of the first branches being a P-R-S pair connection; the P-R-S pair comprises: a moving pair P pair, a first revolute pair R pair and a ball pair S pair, wherein the first revolute pair R pair is arranged on the moving pair P pair, and the ball pair S pair is arranged on the first revolute pair R pair; the tail ends of a plurality of first branched chains are arranged on the same tail end connecting piece;
a lower platform, comprising: a plurality of second branches, each of which comprises a plurality of second revolute pair R pairs connected in series;
wherein the upper platform is mounted on the lower platform;
the ball pair S pair comprises: and the first equivalent S pair, the second equivalent S pair and the third equivalent S pair are formed by intersecting a plurality of rotation axes at one point, wherein the first equivalent S pair, the second equivalent S pair and the third equivalent S pair are all arranged on the revolute pair R pair.
2. The 3PRS-3RRR dual platform device for intelligent assembly of claim 1, wherein the mobile pair P pair comprises: the device comprises a first driving motor, a coupler, a first guide rail, a ball screw and a first sliding block, wherein the first driving motor is connected with the ball screw arranged on the first guide rail through the coupler and drives the ball screw to rotate and drive the first sliding block on the ball screw to move up and down, and the first sliding block is arranged on the ball screw.
3. The 3PRS-3RRR dual platform device for intelligent assembly of claim 2, wherein the first revolute pair R pair is mounted on the first slider.
4. The 3PRS-3RRR dual platform device for intelligent assembly of claim 1, wherein the end connector further has six-dimensional force and moment sensors mounted thereon for detecting contact force and contact moment.
5. The 3PRS-3RRR dual platform device for intelligent assembly of claim 1, wherein the second revolute pair R pair comprises: the device comprises a first R pair, a second R pair and a third R pair, wherein the first R pair is rotatably arranged on a second rack, the first R pair transmits rotary motion through an inner connecting rod, the inner connecting rod is connected with an outer connecting rod through the second R pair, and the outer connecting rod is rotatably connected with a bearing platform through the third R pair.
6. The 3PRS-3RRR dual platform device for intelligent assembly of claim 5, wherein the lower platform further comprises: the first R pairs are arranged on the rotating shaft supporting seat; and/or, further comprising: a second driving motor for driving a plurality of the first R pairs to rotate; and/or, further comprising: the support frame is used for installing the second driving motor.
7. The 3PRS-3RRR dual platform device for intelligent assembly of claim 5, wherein the axes of rotation of a plurality of the first R pairs are coincident.
8. The 3PRS-3RRR dual platform device for intelligent assembly of any one of claims 1 to 7, wherein the number of first branches is three and the upper platform comprises: a 3PRS mechanism having one degree of freedom of movement in a vertical direction and two degrees of freedom of rotation in a plane, i.e., three degrees of freedom; the number of the second branched chains is three, and the lower platform comprises: a 3RRR mechanism having lateral movement, longitudinal movement, and rotation about a vertical direction, i.e., three degrees of freedom; the dual-platform device has complete six degrees of freedom in space.
9. The 3PRS-3RRR dual platform device for intelligent assembly of any one of claims 1 to 7,
the upper platform is connected with a box body through a first rack, and the box body is arranged on the lower platform;
and/or the lower platform is arranged on the electrical cabinet through a second rack;
and/or a first driving controller, a first cooling fan and a first sensor main board are arranged in the box body;
and/or a second driving controller, a second cooling fan and a second sensor main board are arranged in the electrical cabinet;
and/or the electrical cabinet is in a packaging box body form, and the side surface of the electrical cabinet is also provided with an external interface, an emergency stop switch, a status display lamp, a power supply and a control switch.
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| US6135683A (en) * | 1997-11-05 | 2000-10-24 | Jongwon Kim | Parallel mechanism for multi-machining type machining center |
| DE19850708C2 (en) * | 1998-11-03 | 2000-10-26 | Ds Technologie Werkzeugmaschin | Milling head unit |
| KR100471749B1 (en) * | 2002-11-06 | 2005-03-17 | 재단법인서울대학교산학협력재단 | Micro-Motion Machine and Micro-Element Fabricating Machine Using 3 Degree of Freedom Parallel Mechanism |
| CN100446944C (en) * | 2007-04-20 | 2008-12-31 | 天津大学 | Parallel mechanism capable of implementing two degrees of freedom in rotation, and one degree of freedom in translation |
| CN104551714B (en) * | 2015-01-08 | 2017-02-01 | 清华大学 | Parallel mechanism with spatial two rotation and one translation freedom degrees |
| CN106933267A (en) * | 2017-04-24 | 2017-07-07 | 华南理工大学 | A kind of vibration measurement control device and method of hard and soft rod-type plane-parallel type platform |
| CN208614774U (en) * | 2018-06-12 | 2019-03-19 | 浙江理工大学 | A kind of mobile 3-freedom parallel mechanism of two rotation one of driving parallel arrangement |
| CN109191988A (en) * | 2018-11-16 | 2019-01-11 | 上海赢浩机电设备有限公司 | 3-PRS+3-RRR type six freedom-degree motion simulator executing agency |
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