CN205614648U - Redundant driven two -degree -of -freedom spherical surface parallel mechanism of high rigidity - Google Patents

Abstract

The utility model discloses a high-rigidity redundant drive two-degree-of-freedom spherical surface parallel mechanism. The mechanism is mainly composed of a supporting center spherical auxiliary branch chain and four motion branch chains. It is characterized in that: among the four kinematic branch chains, the first kinematic branch chain and the third kinematic branch chain are symmetrically arranged, and the second kinematic branch chain and the fourth kinematic branch chain are symmetrically arranged; the first kinematic branch chain and the fourth kinematic branch chain are symmetrically arranged The three motion branch chains respectively include the U pair connected with the fixed platform, the mobile pair and the ball joint connected with the moving platform; the second movement branch chain and the fourth movement branch chain respectively include the The rotating pair, the moving pair and the spherical joint connected with the moving platform; the supporting center spherical auxiliary branch chain is composed of a central spherical joint connecting the fixed platform and the moving platform. The utility model can realize the two-dimensional rotational movement of the moving platform, and has the advantages of symmetrical structure and driving distribution, convenient arrangement of the driving device, strong bearing capacity and the like.

Description

Two-DOF Spherical Parallel Mechanism with High Stiffness and Redundant Drive

Technical field:

The utility model belongs to the technical field of parallel mechanisms with few degrees of freedom in space, in particular to spherical parallel mechanisms with redundant drives.

Background technique:

Compared with serial robots, parallel robots have the advantages of high rigidity, fast response, and high precision, and are widely used in the field of machinery industry. Due to its simple structure, easy control, low cost and the ability to meet the requirements of many applications with less than 6 degrees of freedom, the parallel robot with less degrees of freedom has become a new hotspot in robot research. Compared with the high-speed parallel mechanism, it has the characteristics of simple structure, relatively low cost of design, manufacture and control.

Spherical parallel mechanism is a special kind of parallel mechanism with few degrees of freedom in space. When the mechanism moves, all the points on the moving platform make a spherical motion around a fixed point with a constant distance. The spherical parallel mechanism has many advantages such as compact structure, flexibility and reliability. Spherical mechanisms have important application value in engineering, and have broad application prospects in aerospace, medical, electronics, machinery and other departments, such as wrist joints for robots, mechanical digital measuring machines, satellite orientation devices, sun tracking devices, radio Telescope, rotary table and part positioning device for machining. In medical engineering, spherical mechanisms can be used as abdominal surgical robots, flexible eyes, laser scanning devices for dental models, retinal anticoagulant injection devices in ophthalmic surgery, and ankle and shoulder joint repairs, etc.

Redundant drives have the advantages of improving the accuracy and fault tolerance of spherical parallel mechanisms, reducing the condition number of the Jacobian matrix of parallel mechanisms (increasing flexibility) and increasing the stiffness of parallel mechanisms. There are generally two ways to redundantly drive parallel mechanisms. One is to directly add drive joints on the basis of the original parallel mechanism on the premise of ensuring that the degree of freedom of the mechanism remains unchanged. Although this method is simple, it increases the asymmetry of the mechanism and affects the dynamic performance of the mechanism. The kinematic inverse and forward solutions of will become more complicated. Another way is to add a branch chain that is exactly the same as the branch chain in the mechanism, and ensure that the degrees of freedom of the mechanism remain unchanged, and then introduce drive joints into the added branch chain to form a redundant drive parallel mechanism. This way can install the driver on the base very easily, maintain the symmetry of the mechanism, make the inverse kinematics solution simple, and can also eliminate the multi-solution problem of the forward kinematics solution.

Invention content:

In order to solve the problems of low support stiffness and poor load capacity of the existing two-degree-of-freedom spherical parallel mechanism, two kinematic branch chains that are identical to the original mechanism are added on the basis of the RPS+UPS+S two-degree-of-freedom spherical parallel mechanism, and The degree of freedom of the mechanism is guaranteed to be unchanged, and then the driving joint is introduced into the added branch chain to form a high-stiffness redundant-driven two-degree-of-freedom spherical parallel mechanism. The mechanism has the advantages of stable support, strong load capacity, and convenient drive arrangement.

The technical scheme adopted in the utility model is:

The two-degree-of-freedom spherical parallel mechanism driven by high-stiffness redundancy is mainly composed of a fixed platform, a moving platform, a supporting center spherical sub-branch connecting the fixed platform and the moving platform, and four kinematic branch chains. It is characterized in that: among the four kinematic branch chains, the first kinematic branch chain and the third kinematic branch chain are symmetrically arranged, and the second kinematic branch chain and the fourth kinematic branch chain are symmetrically arranged.

The first kinematic branch chain and the third kinematic branch chain respectively include a U pair connected with the fixed platform, a moving pair and a ball joint connected with the moving platform; the second kinematic branch chain and the fourth kinematic branch chain The chain respectively includes a revolving pair connected with the fixed platform, a moving pair and a spherical joint connected with the moving platform; the supporting center spherical secondary branch chain is composed of a central spherical joint connecting the fixed platform and the moving platform.

The spherical centers of the five spherical joints connected to the moving platform are in the same plane; the axes of the rotating pair of the second kinematic branch chain connected to the fixed platform are parallel to the axes of the fourth kinematic branch chain; the The U pair of the first kinematic branch chain and the U pair of the third kinematic branch chain are both a T-shaped compound hinge yoke with two axes of rotation pairs perpendicular to each other. The vertical rotation axes of the two Us are collinear and parallel to the second movement The axes of the two rotating pairs in the branch chain and the fourth kinematic branch chain are parallel to each other.

The utility model has the advantages of stable support, strong load capacity, and convenient drive layout. The redundant drive mode makes the robot have better rigidity, and provides a basis for the optimization of the two-degree-of-freedom spherical parallel mechanism type and a larger selection space.

Description of drawings:

Fig. 1 is the three-dimensional structure schematic diagram of the present utility model;

detailed description:

Example 1:

The utility model is described in detail in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, the two-degree-of-freedom spherical parallel mechanism of the high-rigidity redundant drive described in the utility model is mainly composed of a fixed platform (1), a moving platform (2) and a connection between the fixed platform (1) and the moving platform (2). The support center spherical auxiliary branch chain and four motion branch chains are composed.

The supporting center spherical secondary branch chain is composed of a central spherical joint (OS) connecting the fixed platform (1) and the moving platform (2), and the spherical center of the central spherical joint (OS) is the two-degree-of-freedom spherical surface The center of motion of a parallel mechanism.

The four kinematic branch chains are respectively the first kinematic branch chain (connected by U pair 1U, connecting rod 11, moving pair 1P, connecting rod 12, and ball joint 1S in sequence), the second kinematic branch chain (successively formed by rotating Auxiliary 2R, connecting rod 21, moving pair 2P, connecting rod 22, ball hinge 2S are connected), the third motion branch chain (by U pair 3U, connecting rod 31, moving pair 3P, connecting rod 32, ball hinge 3S in sequence connected), the fourth kinematic branch chain (connected by rotating pair 4R, connecting rod 41, moving pair 4P, connecting rod 42, spherical hinge 4S successively)). Wherein, the first kinematic branch chain and the third kinematic branch chain are symmetrically arranged, and the second kinematic branch chain and the fourth kinematic branch chain are symmetrically arranged.

The first motion branch chain is connected to the fixed platform 1 through the U pair 1U, and the first movement branch chain is connected to the moving platform 2 through the ball joint 1S. The second kinematic branch chain is connected with the fixed platform 1 through the revolving pair 2R, and the second kinematic branch chain is connected with the moving platform 2 through the ball joint 2S. The third motion branch chain is connected with the fixed platform 1 through the U pair 3U, and the third motion branch chain is connected with the moving platform 2 through the ball joint 3S. The fourth motion branch chain is connected with the fixed platform 1 through the rotating pair 4R, and the fourth motion branch chain is connected with the moving platform 2 through the ball joint 4S.

The centers of spheres of the five spherical hinges 1S, 2S, 3S, 4S, and OS connected to the moving platform are in the same plane; The axes of the rotating pair 4R of the chain are parallel to each other; the U pair 1U of the first kinematic branch chain and the U pair 3U of the third kinematic branch chain are both a T-shaped composite hinge yoke with two rotating pair axes orthogonal to each other. The vertical rotation axes of the U-frames 1U, 3U are collinear and parallel to the axes of the two revolving pairs 2R, 4R in the second kinematic branch chain and the fourth kinematic branch chain.

The driving pairs of the mechanism are hydraulic cylinders or electric cylinders, which are respectively installed on the moving pairs 1P, 2P, 3P and 4P of the four motion branch chains. The drive pairs 1P and 3P on the first motion branch chain and the third motion branch chain drive and the drive pairs 2P and 4P on the second motion branch chain and the fourth motion branch chain operate in pairs, one pull and one push, drive The moving platform 2 performs a spherical motion centered on the spherical center of the central spherical hinge OS.

Claims (2)

1. The two degrees of freedom sphere parallel mechanism of the highest rigidity redundant drive, mainly by fixed platform (1), moving platform (2) and connection Support center spherical pair side chain and four movement branched chain of fixed platform (1) and moving platform (2) are constituted；It is characterized in that: described four The first movement branched chain and the 3rd movement branched chain in article movement branched chain are arranged symmetrically with, the second movement branched chain and the 4th movement branched chain pair Claim to arrange；The first described movement branched chain and the 3rd movement branched chain, include the most successively the U that is connected with fixed platform (1) secondary (1U, 3U), moving sets (1P, 3P) and the ball pivot (1S, 3S) that is connected with moving platform (2)；The second described movement branched chain and the 4th fortune Dynamic side chain, includes revolute pair (2R, 4R), moving sets (2P, 4P) and and the moving platform being connected with fixed platform (1) the most successively (2) ball pivot (2S, 4S) connected；Described support center spherical pair side chain, is connected fixed platform (1) and moving platform (2) by one Center ball pivot (0S) forms.
2. The two degrees of freedom sphere parallel mechanism of high rigidity redundant drive the most according to claim 1, it is characterised in that: described The centre of sphere of five ball pivots (1S, 2S, 3S, 4S, 0S) being connected with moving platform (2) is in the same plane；Described and fixed platform (1) connects The revolute pair (2R) of the second movement branched chain connect is parallel to each other with the axis of the revolute pair (4R) of the 4th movement branched chain；Described first The U secondary (3U) of the U of movement branched chain secondary (1U) and the 3rd movement branched chain is answering of T-shaped two revolute pair orthogonal axes anyhow Close hinge crotch, the vertical rotating axis collinear of two U width (1U, 3U) and with two in the second movement branched chain and the 4th movement branched chain The axis of revolute pair (2R, 4R) is parallel to each other.