RO127277A2 - Method and modules for reconfiguration of parallel robots - Google Patents

Abstract

The invention relates to a method for obtaining, by reconfiguration, a system of parallel robots having various mobility degrees and to some modules necessary for such a reconfiguration, respectively. According to the invention, the method consists, in a first stage, in selecting the number of mobility degrees (M) of a robot, then selecting the number (b) of linkages of PSR type so that, finally, a number (a) of linkages of PSU type results based on the relation M=a+b, the reconfigurability of the structures being ensured by using the same mounting dimensions between the connection elements of some kinematic couples. The modules claimed by the invention have two combinations of linkages: a linkage (SPU) comprising three joints (1, 2 and 3), namely a spherical joint, a prism-shaped joint and a universal joint, and a linkage (SPR) comprising three joints (4, 5 and 6), namely a shperical joint, a prism-shaped joint and a rotation joint, where a reconfigurable joint can integrate only SPR linkages, only PSU linkages or combinations of PSR and PSU linkages, the linkages of the same type in a structure being identical.

Description

The invention relates to a method of obtaining by reconfiguration of a system of parallel robots with different degrees of mobility and respectively to the typical and modularized elements necessary for this reconfiguration.

Parallel robots have a fixed platform and a mobile platform, the two platforms being connected through a number of identical or different kinetic chains. Depending on the number of kinetic chains, the number and type of active and passive couples, a wide range of parallel robots with varying degrees of mobility have been developed. The choice of a certain structure, with a certain number of degrees of mobility is also made according to the specificity of the application that the robot will serve.

The design and realization of the desired structure of a parallel robot presents disadvantages related to the particularities of each structure, because each structure contains its own elements.

Also, there are known methods of realizing reconfigurable structures of parallel robots that use kinematic chains and modularized links that allow the configuration and reconfiguration of the robot. The disadvantage of the known methods is due to the fact that they allow only a limited range of robots and, in some cases, they require structure-specific elements. Another disadvantage of the known methods is that it does not offer an algorithm on which to choose the modules according to the desired structure.

The technical problem that the invention solves consists in the realization of a system of reconfigurable parallel robots by using a method of generating the kinematic schemes of these robots and by using typical constructive elements that make it possible to reconfigure the structures.

The method of generating the kinematic schemes offers a system of relations and an algorithm for generating the topology of the robot which is based on two types of basic modules.

Two types of kinematic chains are used to create reconfigurable structures:

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- kinematic chain called SPU (Sphere - Prismatic - Universal) which is composed of a spherical joint, a prismatic joint having the role of torque motors and respectively a universal joint, of cardan cross type.

- kinematic chain called SPR (Spherical-Prismatic-Rotational) which is composed of a spherical joint, a prismatic joint and a rotating joint respectively.

In determining the topological variants of the system of parallel robots reconfigurable with vertical actuators, the following hypotheses are considered:

a) each robot has a fixed platform and at most one mobile platform;

b) the mobile platform is connected to the fixed platform only with kinematic chains of the type SPR and / or SPU;

c) the number of kinetic chains of the SPU type is noted with a;

d) the number of SPR-type kinetic chains is noted with b;

e) all prismatic joints are active (motors).

The degree of mobility of a parallel robot whose elements are not subject to common geometrical constraints is calculated by the relation:

M = 6n-SC5-4C4-3C3-2C2-C1 (1) where: M is the degree of mobility of the robot, n - the number of movable elements of the robot,

Ci, (i = l, 5) - the number of joints that allow (6-i) movements.

It is observed that:

ί Ξ: Ο _Λ α>0.6> 0 (2) n = 2a + 2b + 1 (3) CS = a + 2b (4) C4 = a (5) <73 = a + b (6)

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C2 = CI = O i

replacing relations (3), ... (7) in relation (1) results:

(7)

M = 6-b, (8)

It was also observed that:

(9)

From relations (8) and (9) it follows:

a = 0, b = 3, M = 3, a = 2, b = 2, M-4, (10) (H)

= 4, b = l, M = 5, (12) = 6, b = 0, M = 6, (13)

Relationships (10) define topologically the reconfigurable parallel robot with three degrees of mobility, consisting of a fixed platform, a mobile platform and three kinematic chains of the SPR type (b = 3).

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Relationships (11) define topologically the reconfigurable parallel robot with four degrees of mobility, consisting of a fixed platform, a mobile platform, two kinematic chains of the SPU type (a = 2) and two kinematic chains of the SPR type (b = 2).

Relationships (12) define topologically the reconfigurable parallel robot with five degrees of mobility, consisting of a fixed platform, a mobile platform, four kinematic chains of the SPU type (a = 4) and a kinematic chain of the SPR type (b = l).

Relationships (13) define topologically the reconfigurable parallel robot with four degrees of mobility, consisting of a fixed platform, a mobile platform and six kinematic chains of the SPU type (a = 6).

The following is an example of the application of the invention in connection with FIGS. 1, 10, which represents:

- Figure 1, schematic of the SPU kinematic chain;

- figure 2, the schematic of the SPR kinematic chain;

- figure 3, the diagram of a robot with three degrees of freedom;

- figure 4, the diagram of a robot with four degrees of freedom;

- figure 5, the diagram of a robot with five degrees of freedom;

figure 6, the diagram of a robot with six degrees of freedom;

- figure 7, rotation torque;

- figure 8, the universal coupling;

- Figure 9, the spherical coupling.

The system of parallel robots reconfigurable with proposed vertical actuators contains four variants according to the invention, which can be reconfigured by adding or removing kinetic chains.

The system uses two types of kinetic chains: SPU and SPR. A kinematic chain called SPU - Sphere - Prismatic - Universal, (figure 1) which consists of a spherical joint (1), a prismatic joint (2) and a universal joint (3) respectively.

Another type of kinematic chain (figure 2), called SPR (Spherical-Prismatic-Rotational) is composed of a spherical joint (4), a prismatic joint (5) and a rotating joint (6) respectively.

By combining a number of SPU kinetic chains with a b number of SPR kinetic chains, variants of parallel robots with 3, 4, 5 and 6 degrees of freedom result.

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The structure of a parallel robot with three degrees of mobility (figure 3) contains three SPR-type kinetic chains that connect a fixed platform (9) with a mobile platform (10). The kinematic diagram of this robot consists of: fixed platform (9), mobile platform (10), spherical joints (11), (12), (13), prismatic joints (14), (15), (16) and joints of rotation (17), (18), (19).

The variant of a robot with four degrees of mobility (figure 4) contains two kinematic chains of the type SPR and respectively two chains of the type SPU, which connect the fixed platform (9) with the mobile platform (10). The kinematic scheme of this robot consists of: fixed platform (9), mobile platform (10), spherical joints (20), (21), (22), (23), prismatic joints (24), (25), ( 26), (27), universal joints (28), (29), and rotary joints (30), (31).

The variant of the robot with five degrees of mobility (figure 5) contains a kinematic chain of the SPR type and four chains of the SPU type respectively that connect a fixed platform (9) with a mobile platform (10). The kinematic diagram of this robot consists of: fixed platform (9), mobile platform (10), spherical joints (32), (33), (34), (35), (36) prismatic joints (37), (38 ), (39), (40), (41), universal joints (42), (43), (44), (45) and rotary joint (46).

The structure of the robot with six degrees of mobility (Figure 6) contains six chains of the SPU type with which the fixed platform (9) connects with the mobile platform (10). The kinematic diagram of this robot consists of: fixed platform (9), mobile platform (10), spherical joints (47), (48), (49), (50), (51), (52), prismatic joints ( 53), (54), (55), (56), (57), (58), universal joints (59), (60), (61), (62), (63), (64).

The reconfigurability of the structures is ensured by using the same mounting dimensions between the elements that make up the robots. Thus, the rotating joint (figure 7), the universal joint (figure 8), the spherical joint (figure 9) and the fastening element (figure 10) have mounting dimensions (L and D).

The rotation torque 6 consists of an element 65 and an element 66, both having the terminal parts with mounting dimensions L and D identical.

The universal coupling 3 is composed of an element 67 and an element 68 and a cardan 69. The connecting elements 67 and 68 have the terminal parts with the mounting dimensions L and D identical.

The spherical coupling 1 is composed of a cardan 70 and two elements 71 and 72 having the terminal parts with mounting dimensions L and D identical.

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The connection between the couples from the part of the fixed platform 9 and those from the part of the mobile platform 10 is made through the translation couples.

The following advantages are obtained by applying the invention;

reconfigurable structure, with easy possibilities of extension or restriction;

- generating the kinematic scheme by conveniently choosing the number b of the SPU type chains;

the use of typical kinematic couplings;

- low cost and high reliability.

Claims (4)

1. The method of generating kinematic structures for reconfigurable parallel robots, robots consisting of a fixed platform (9), a mobile platform (10), a number of kinematic type chains (PSUs), each PSU chain being composed of -a serum torque (1), a prismatic torque (2), with the role of a torque motor and a universal torque (3), a number of kinematic chains (PSR), composed of a spherical torque (4), a prismatic couple (5) and a rotation couple (6), characterized in that, in order to achieve reconfigurable structures of robots, in the first stage the number of degrees of freedom M of the robot is chosen, during the second stage, choose the number b of kinetic chains b of type PSR, then, based on the relation M = a + b results the number a of kinetic chains of type (PSU), the reconfigurability of the structures being ensured by using the same mounting dimensions between the connection elements of the couples cinematics. 2. The method of generating kinematic structures for reconfigurable parallel robots, characterized in that the topology of the robot with three degrees of freedom given by the relation (10) consists of a fixed platform (9), a mobile platform (10) and a number of three PSR kinetic chains (b = 3), the topology of the robot with four degrees of freedom given by the relation (11) consists of a fixed platform (9), a mobile platform (10), a number of two kinetic chains of PSR type (b = 2) and a number of two PSU type chains (a = 2), the topology of the robot with five degrees of freedom given by the relation (12) consists of a fixed platform (9), a mobile platform ( 10), a kinematic chain of type PSR (b = 1) and a number of four kinematic chains of type PSU (a = 4), and the topology of the robot with six degrees of freedom given by the relation (12) consists of a fixed platform (9), a mobile platform (10) and a number of six PSU chains (a = 6). 3. Modules of reconfiguration of parallel robots, characterized in that they use two combinations of types of kinetic chains, a kinematic chain called (SPU), which consists of a spherical joint (1), a prismatic joint (2) and respectively a universal joint (3) and another type of kinematic chain, called (SPR), consisting of a spherical joint (4), a prismatic joint (5) and a rotating joint (6), respectively, a reconfigurable structure integrate only type chains (SPR), only type chains (PSU) or combinations of chains (PSR) and (PSU), the chains of the same type in a structure being identical. ^ -2010-00887-2 k -09- 2010 4. Parallel robot reconfiguration modules according to claim 3, characterized in that the reconfigurability of the structures is ensured by using the same mounting dimensions between the couplings (1), (2), (3) and (6) that form the kinematic chains, all having the connecting elements with the mounting dimensions (L and D) identical.