CN107139165A - The Six-freedom-degree space docking mechanism of series-parallel connection - Google Patents

Abstract

A six-degree-of-freedom adjustment mechanism includes a bottom-up two-dimensional translation platform, a parallel lifting mechanism and a parallel adjustment platform. The two-dimensional mobile platform provides degrees of freedom in the X and Y directions; the parallel lifting mechanism is The ultra-statically indeterminate structure realizes the freedom of movement in the Z direction through four RPR branch chains, which not only increases the rigidity and stability of the mechanism, but also improves the speed resolution of the lift to a certain extent; the parallel adjustment platform has an X, Y, Z rotation degrees of freedom, the ball joint connection in the middle increases the bearing capacity of the installation and adjustment platform, and at the same time reduces the load of the other four drive branch chains. Compared with the traditional parallel adjustment platform, the present invention completely decouples movement and rotation through a layered drive strategy. Through kinematics analysis and finite element analysis, the invention has good stability and rigidity, relatively simple system control, and fully meets the requirements for installation and adjustment of medium-sized and large-scale devices.

Description

Hybrid six-degree-of-freedom space docking mechanism

technical field

The invention relates to space motion docking, in particular to a hybrid six-degree-of-freedom space docking mechanism.

Background technique

In 1965, German Stewart published the famous article "Six Degrees of Freedom Platform" on the British magazine ImechE. The platform includes three motion branches, and the platform can perform six degrees of freedom. The platform is used in flight simulators. Since then, the parallel platform gradually entered people's field of vision and became a research hotspot. New processing equipment based on this principle is constantly emerging, because of its good dynamic characteristics, it is widely used in production activities and is mainly used in the assembly industry, such as the application of Stewart mechanisms to automobile assembly lines, autonomous walking robots, and robot arms. Since the mechanism is a highly coupled system, it is difficult to obtain the forward kinematics solution and the kinematics control is difficult.

Investigating Chinese invention patents in recent years, Lu Yi of Yanshan University and others invented a 3-handed 3SPR+3RPS series-parallel robot. The series connection of two parallel robots with three branches is a six-degree-of-freedom gripper. mechanism. This type of mechanism has redundant degrees of freedom, but poor stiffness and small movement space. Cao Chongzhen of Shanghai Jiaotong University and others used three identical two-drive branches to form a mobile six-degree-of-freedom hybrid robot, and realized the six-degree-of-freedom movement of the moving platform, resulting in good decoupling of each branch chain and no accumulated error. Li Xining of Northwestern Polytechnical University and others connected the XY two-dimensional motion platform, the Z-axis rotation platform and the 3RHS parallel platform in series to form a six-degree-of-freedom hybrid mechanism, which is used for the pose adjustment of small and medium-sized parts of the aircraft. Realize partial decoupling of the mechanism and flexible adjustment of six degrees of freedom. Yu Xiaoliu of Anhui University of Technology and others invented a six-degree-of-freedom robot pose detection device based on a series-parallel mechanism, which can take into account both the detection accuracy and the work space requirements, and realize the comprehensive measurement and real-time display of the position and posture of the measured object, which improves the Check line rate. Chen Wuyi of Beijing University of Aeronautics and Astronautics disclosed a six-degree-of-freedom redundant parallel mechanism. Aiming at the shortcomings of small working space and small attitude space of the parallel mechanism, the connection relationship between the two ends of the branch chain and the spherical joint and the rotating pair are changed. The motion relationship of the moving platform relative to the circular guide rail effectively solves the adjustment of the singular pose of the workpiece on the parallel mechanism.

After a comprehensive analysis of the above mechanism, it is found that the advantages and disadvantages of the parallel mechanism are very obvious. Its small movement space limits the application of the parallel mechanism in industry, and it is used in the adjustment of small parts. Coupling is not ideal leading to control difficulties. Therefore, a mechanism that takes into account the space travel of the mechanism, the rigidity of the mechanism, the stability and the ease of control is still a difficult problem to be solved.

Contents of the invention

The invention provides a six-degree-of-freedom adjustment mechanism, which has a large working space, stable operation and good structural rigidity to ensure that it can bear a large load. It has wide application value and development prospects for the clean and precise adjustment and installation of modular components of large devices, aerospace detection equipment, underground mining equipment, disaster rescue equipment and other adjacent areas.

Technical solution of the present invention is as follows:

A six-degree-of-freedom adjustment mechanism is characterized in that the mechanism includes a bottom-up two-dimensional translation platform, a parallel lifting mechanism and a parallel adjustment platform:

The two-dimensional translation platform includes a bottom-up base plate, a first moving plate and a second moving plate; the first moving guide rail and the second moving guide rail are parallel to each other and installed on the right and left sides of the base plate, while The first slider and the second slider are respectively installed on the first moving guide rail and the second moving guide rail correspondingly and connected with the bottom of the first moving plate; the third moving guide rail and the fourth moving guide rail are installed parallel to each other on The rear and front ends of the first moving plate, the third slider and the fourth slider are respectively installed on the third moving guide rail and the fourth moving guide rail and are connected with the second moving plate The direction of the first moving guide rail, the second moving guide rail and the third moving guide rail and the fourth moving guide rail are perpendicular to each other; the first supporting base and the second supporting base are installed on the described moving guide rail by screws The two ends in the middle of the bottom plate are used for the installation of the first screw rod. The direction of the first screw rod is parallel to the second moving guide rail and is located in the middle of the first moving guide rail and the second moving guide rail. The first nut bracket is fixed on the lower surface of the first moving plate, the first motor is installed on one side of the first screw rod, and the first motor and the first screw rod form the driving module of the first moving plate; The three support bases and the fourth support base are installed on the left and right ends of the first moving plate by screws for the installation of the second screw rod. The direction of the second screw rod is parallel to the fourth moving guide rail and located at the third moving guide rail. In the middle of the guide rail and the fourth moving guide rail, the second nut bracket sleeved on the second screw rod is fixed on the lower surface of the second moving plate, and the second motor is installed on one side of the second screw rod. The second motor and the second screw rod form the driving module of the second moving plate;

The parallel lifting mechanism includes a base, 4 RPR branch chains and a moving platform, the base is fixed on the second moving plate, and the four RPR branch chains are respectively moved by the lower end rotating pair, the middle pair and the upper revolving pair are connected in series to form a linear drive branch, the lower revolving pair of each RPR is connected to the base, the upper revolving pair is connected to the moving platform, and the kinematic pairs at both ends of the four RPR branch chains are connected to the The connection between the above-mentioned base and the moving platform is distributed in a symmetrical cross shape, forming a 4RPR mechanism;

The parallel adjustment platform includes a fixed platform, 4 SPS branch chains, a center branch chain and a moving platform, the fixed platform is fixed on the moving platform of the parallel lifting mechanism, and the center support The upper end of the chain is the upper end ball dumpling, the lower end is a flange plate, the upper end ball joint is connected with the center of the moving platform, and the flange plate of the center branch chain is fixedly connected with the described fixed platform through the connecting frame. The central branch of the chain passes through the connecting frame and the center line of the central branch coincides with the center line of the connecting frame;

The four SPS branch chains are all composed of upper spherical hinges, moving pairs and lower spherical hinges in series. The four lower spherical hinges of the SPS branch chains are hinged on the fixed platform. The four corners are distributed in a square shape. An upper ball hinge is hinged at the four corners of the moving platform and is distributed in a rectangle, and the positioning platform is located directly below the moving platform, forming a 4SPS-S mechanism. The two-dimensional moving platform, the fixing platform and the The centers of the moving platforms are on the same vertical line.

The four branch chains of the parallel lifting mechanism are divided into two driving branch chains and two driven branch chains, and the driven branch chains and the driving branch chains are respectively symmetrically distributed.

The advantages of the present invention are:

1. The two-dimensional mobile platform of the six-degree-of-freedom adjustment mechanism of the present invention provides the freedom of movement in the X and Y directions; the 4RPR parallel lifting mechanism is a super-static structure, and the freedom of movement in the Z direction is realized through four RPR branch chains, which not only increases The rigidity and stability of the mechanism are improved, and the speed resolution of the lifting can be improved to a certain extent; the 4-SPS-1S installation and adjustment platform has rotation degrees of freedom along X, Y, and Z, and the spherical hinge connection of the central branch increases the installation Adjust the carrying capacity of the platform while reducing the load on the other four drive chains. The two-dimensional translation stage and the 4RPR mechanism provide a large-stroke movement in the three directions of X, Y, and Z, and have a large working space. The statically indeterminate structure makes the structure have high stability and good rigidity, and at the same time, the structure is simple and can carry a large load. The installation and leveling mechanism uses the four-point leveling center fixing principle, and the mechanism has high rigidity, strong bearing capacity, fast speed, and no accumulated error.

2. The six-degree-of-freedom adjustment mechanism of the present invention has wide application value and development prospects in the clean and precise adjustment and installation of large-scale device modular components, aerospace detection equipment, underground mining equipment, and disaster rescue equipment.

Description of drawings

Fig. 1 is a three-dimensional structural schematic diagram of a six-degree-of-freedom adjustment mechanism of the present invention;

Fig. 2 is the assembly diagram of the two-dimensional translation stage of the present invention

3 is a half-sectional view of the assembly of the two-dimensional translation platform of the present invention;

Figure 4 is a top view of the 4RPR parallel lifting mechanism module

Figure 5 is a three-dimensional schematic diagram of a 4RPR parallel lifting mechanism module;

Figure 6 is a schematic diagram of the 4SPS-1S parallel adjustment platform;

Fig. 7 is a half-sectional schematic diagram of a six-degree-of-freedom adjustment mechanism of the present invention;

Fig. 8 is a top view of the six-degree-of-freedom adjustment mechanism of the present invention.

detailed description

Please refer to Figures 1 to 8, it can be seen from the figures that the six-degree-of-freedom adjustment mechanism of the present invention includes a bottom-up two-dimensional translation platform 1, a parallel lifting mechanism 2 and a parallel adjustment platform 3:

The two-dimensional translation platform 1 includes a bottom-up bottom plate 1-1, a first moving plate 1-3 and a second moving plate 1-6; a first moving guide rail 1-11 and a second moving guide rail 1-14 are parallel to each other and installed on the right and left sides of the bottom plate 1-1, while the first slider 1-2 and the second slider 1-15 are respectively installed on the first moving guide rail 1-11, The second moving guide rail 1-14 is connected to the bottom of the first moving plate 1-3; the third moving guide rail 1-5 and the fourth moving guide rail 1-10 are installed parallel to each other on the first moving plate 1-3 The rear and front ends on the top, the third slider 1-2 and the fourth slider 1-9 are installed on the third moving guide rail 1-5 and the fourth moving guide rail 1-10 respectively and are connected with the described The bottom of the second moving plate 1-6 is connected, the first moving guide rail 1-11, the second moving guide rail 1-14 are connected with the third moving guide rail 1-5, the fourth moving guide rail 1-10 The direction is perpendicular to each other; the first support seat 1-13 and the second support seat 1-17 are installed on the two ends in the middle of the bottom plate 1-1 by screws for the installation of the first screw rod 1-12, and the first screw rod 1-12 The direction is parallel to the second moving guide rail 1-14 and is located in the middle of the first moving guide rail 1-11 and the second moving guide rail 1-14, and the first nut sleeved on the first screw rod 1-12 The bracket 1-16 is fixed on the lower surface of the first moving plate 1-3, the first motor is installed on one side of the first screw 1-12, and the first motor and the first screw rod form the first moving plate. The drive module of the plate 1-3; the third support seat 1-7 and the fourth support seat 1-19 are installed on the left and right ends of the first moving plate 1-3 through screws for the installation of the second screw rod 1-8, the second The direction of the second screw 1-8 is parallel to the fourth moving guide rail 1-10 and is located in the middle of the third moving guide rail 1-5 and the fourth moving guide rail 1-10, and is sleeved on the second screw rod 1-10. The second nut bracket 1-18 on 8 is fixed on the lower surface of the second moving plate 1-6, and the second motor is installed on one side of the second screw rod 1-8, and the second motor and the second The screw rod constitutes the driving module of the second moving plate 1-6;

The parallel lifting mechanism 2 includes a base 2-1, 4 RPR branch chains and a moving platform 2-2, the base 2-1 is fixed on the second moving plate 1-6, The four RPR branch chains are respectively composed of lower end rotating pairs 2-4, 2-5, 2-8, 2-10, middle moving pairs 2-3, 2-6, 2-7, 2-9, upper end rotating pairs 2- 15, 2-16, 2-17, and 2-18 are connected in series to form a linear drive branch. The lower end of each RPR is connected to the base 2-1, and the upper end of the rotation pair is connected to the moving platform 2-1. 2 are connected, and the kinematic pairs at both ends of the four RPR branch chains are connected to the base 2-1 and the moving platform 2-2 in a symmetrical cross-shaped distribution;

The parallel adjustment platform 3 includes a fixed platform 3-17, 4 SPS branch chains, a central branch chain 3-6 and a moving platform 3-8, and the fixed platform 3-17 is fixed on the On the moving platform 2-2 of the parallel lifting mechanism, the upper end of the center branch chain 3-6 is the upper ball dumpling 3-11, the lower end is a flange 3-18, and the upper end ball hinge 3-11 is connected to the The center of the moving platform 3-8 is connected, and the flange plate 3-18 at the lower end of the center branch chain is fixedly connected to the fixed platform 3-17 through the connecting frame 3-3, and the center branch chain 3-6 wears The center line of the connecting frame 3-3 and the central branch chain (3-6) coincides with the center line of the connecting frame 3-3; the four SPS branch chains 3-2, 3-5 . 3-7, 3-9, 3-10, 3-12 are connected in series, and the four lower spherical hinges 3-7, 3-9, 3-10, 3-12 of the SPS branch chain are hinged on the fixed platform 3 The four corners on the -17 are distributed in a square shape, and the four upper spherical hinges 3-1, 3-4, 3-14, and 3-16 are hinged on the four corners of the moving platform 3-8 and are distributed in a rectangular shape. The fixed platform 3-4 is located directly below the movable platform 3-8, forming a 4SPS-1S mechanism, and the centers of the two-dimensional mobile platform 1, the fixed platform 3-4 and the movable platform 3-8 are at the same on a vertical line.

The four branch chains of the parallel lifting mechanism 2 are divided into two driving branch chains and two driven branch chains, and the driven branch chains and the driving branch chains are respectively symmetrically distributed.

The drive input of the two-dimensional mobile platform 1 is two mutually perpendicular second lead screws 1-8 and the first lead screw 1-12, and the drive input of 4RPR is two mutually symmetrical branch chains 2-3, 2 -7, the drive input of 4SPS-1S is four branch chains 3-2, 3-5, 3-13, 3-15, and the whole system is eight drive inputs 1-8, 1-12, 2-3, 2- 7, 3-2, 3-5, 3-13, 3-15, six outputs, the first four inputs control three-dimensional (X, Y, Z) movement components, 4SPS-1S four inputs are control inputs for three-axis rotation components , to realize the decoupling of translation and rotation. Realize the adjustment and docking of the six degrees of freedom of the module.

Experiments show that the two-dimensional mobile platform of the six-degree-of-freedom adjustment mechanism of the present invention provides freedom of movement in the X and Y directions; the 4RPR parallel lifting mechanism is an ultra-static structure, and the freedom of movement in the Z direction is realized through four RPR branch chains, not only The rigidity and stability of the mechanism are increased, and the speed resolution of the lifting can be improved to a certain extent; the 4-SPS-1S installation and adjustment platform has rotation degrees of freedom along X, Y, and Z, and the ball joint connection of the central branch chain is increased. Install and adjust the bearing capacity of the platform, and at the same time reduce the load of the other four drive branch chains. The two-dimensional translation stage and the 4RPR mechanism provide a large-stroke movement in the three directions of X, Y, and Z, and have a large working space. The statically indeterminate structure makes the structure have high stability and good rigidity, and at the same time, the structure is simple and can carry a large load. The installation and leveling mechanism uses the four-point leveling center fixing principle, and the mechanism has high rigidity, strong bearing capacity, fast speed, and no accumulated error.

The six-degree-of-freedom adjustment mechanism of the present invention has wide application value and development prospects in the clean and precise adjustment and installation of modular components of large-scale devices, aerospace detection equipment, underground mining equipment, disaster rescue equipment, and the like.

Claims (2)

1. a kind of six degree of freedom adjustment mechanism, it is characterised in that：The mechanism includes two-dimension translational platform (1) from bottom to top, parallel connection Lifting mechanism (2) and parallel regulating platform (3)：

Described two-dimension translational platform (1) includes bottom plate (1-1), the first dynamic plate (1-3) and the second dynamic plate (1-6) from bottom to top； First moving guide rail (1-11) and the second moving guide rail (1-14) are parallel to each other and the right left side on described bottom plate (1-1) Both sides, while the first sliding block (1-2) and the second sliding block (1-15) are respectively correspondingly arranged on the first described moving guide rail (1- 11), it is connected on the second moving guide rail (1-14) and with the lower section of the first dynamic plate (1-3)；3rd moving guide rail (1-5) and the 4th is moved Move the rear preceding two ends that guide rail (1-10) is parallel to each other on the described first dynamic plate (1-3), the 3rd sliding block (1-2) and the 4th Sliding block (1-9) is respectively correspondingly arranged on the 3rd described moving guide rail (1-5), on the 4th moving guide rail (1-10) and with it is described The second dynamic plate (1-6) lower section connection, described the first moving guide rail (1-11), the second moving guide rail (1-14) with it is described 3rd moving guide rail (1-5), the direction of the 4th moving guide rail (1-10) are mutually perpendicular to；First support base (1-13), the second support The two ends that seat (1-17) is arranged in the middle of described bottom plate (1-1) by screw are installed for the first screw rod (1-12), the first screw rod The direction of (1-12) is parallel with described the second moving guide rail (1-14) and positioned at described the first moving guide rail (1-11) and the The centre of two moving guide rails (1-14), the first nut bracket (1-16) being set on the first screw rod (1-12) is fixed on described The lower surface of first dynamic plate (1-3), the first motor is arranged on the side of the first screw rod (1-12), the first described motor and first The drive module of the dynamic plate (1-3) of screw mandrel composition first；3rd support base (1-7) and four-supporting (1-19) are installed by screw Left and right ends in the middle of the first dynamic plate (1-3) supply the installation of the second screw rod (1-8), the direction of the second screw rod (1-8) with it is described The 4th moving guide rail (1-10) it is parallel and in described the 3rd moving guide rail (1-5) and the 4th moving guide rail (1-10) Between, the second nut bracket (1-18) being set on the second screw rod (1-8) is fixed on the following table of the dynamic plate (1-6) of described second Face, the second motor is arranged on the side of the second screw rod (1-8), the second described motor and the dynamic plate (1- of the second screw mandrel composition second 6) drive module；

Described lifting mechanism in parallel (2) includes a pedestal (2-1), 4 RPR side chains and a moving platform (2-2), described Pedestal (2-1) is fixed on the dynamic plate (1-6) of described second, four RPR side chains respectively by lower end revolute pair (2-4,2-5,2-8, 2-10), middle prismatic pair (2-3,2-6,2-7,2-9), upper end revolute pair (2-15,2-16,2-17,2-18) each in series one Individual linear drives branch, each RPR lower end revolute pair is connected with described pedestal (2-1), and upper end revolute pair is moved with described Platform (2-2) is connected, and the connection of the kinematic pair at the two ends of four RPR side chains and described pedestal (2-1) and moving platform (2-2) is equal In symmetrical crossing distribution, 4RPR mechanisms are constituted；

Described parallel regulating platform (3) include a fixed platform (3-17), 4 SPS side chains, a center side chain (3-6) and One moving platform (3-8), described fixed platform (3-17) is fixed on the moving platform (2-2) of described lifting mechanism in parallel, institute The upper end for the center side chain (3-6) stated is upper end ball dumpling (3-11), and lower end is a ring flange (3-18), upper end ball pivot (3-11) Be connected with the center of described moving platform (3-8), the ring flange (3-18) of the lower end of the center side chain by link (3-3) with Described fixed platform (3-17) is fixedly connected, and described center side chain (3-6) passes through described link (3-3) and center side chain The center line of (3-6) is overlapped with the center line of described link (3-3)；

4 described SPS side chains (3-2,3-5,3-13,3-15) are by upper ball pivot (3-1,3-4,3-14,3-16), prismatic pair (3-2,3-5,3-13,3-15) and lower ball pivot (3-7,3-9,3-10,3-12) are in series, lower ball pivot (3-7,3- of SPS side chains 9th, 3-10,3-12) it is hinged on the square distribution in corner on described fixed platform (3-17), described upper ball pivot (3-1,3- 4th, 3-14,3-16) corner of described moving platform (3-8) and rectangular distribution are hinged on, described fixed platform (3-4) is located at institute The underface for the moving platform (3-8) stated, constitutes 4SPS-1S mechanisms, described two-dimensional movement platform (1), fixed platform (3-4) and moves The center of platform (3-8) is on same vertical curve.

2. six degree of freedom adjustment mechanism according to claim 1, it is characterised in that the 4 of described lifting mechanism in parallel (2) Bar side chain is divided into driving side chain and each two of driven side chain, and driven side chain and driving side chain are each symmetrical.