CN-121973157-A - Three-degree-of-freedom parallel mechanism with two space rotation and one space movement and mechanical device

CN121973157ACN 121973157 ACN121973157 ACN 121973157ACN-121973157-A

Abstract

The present disclosure provides a three-degree-of-freedom parallel mechanism with two-rotation and one-movement space, which comprises a fixed platform, a movable platform and three main branched chains. Each main chain supports the movable platform to realize the three-degree-of-freedom motion of two rotation and one movement, and each main chain comprises a first branched chain and a second branched chain, wherein the first end of the first branched chain and the first end of the second branched chain are connected with the spherical surface of the movable platform through an equivalent spherical hinge, the second end of the first branched chain is rotationally connected with the fixed platform, and the second end of the second branched chain is rotationally connected with the fixed platform through a revolute pair. The parallel mechanism has the advantages of strong bearing capacity, high rigidity, high fault tolerance capability, high reliability and high stability, can realize stable support and stable motion of the movable platform, realizes spherical connection through an equivalent spherical hinge, realizes three-degree-of-freedom flexible motion with two rotation and one movement only through a rotation hinge mode, and has the advantages of large working space, small accumulated error, timely motion response and high motion output efficiency and precision.

Inventors

LIU XIAOFEI
ZHOU HAN
Bu Yuantao
HE JINYANG
WANG YU

Assignees

燕山大学

Dates

Publication Date: 20260505
Application Date: 20260317

Claims (7)

1. A three degree of freedom parallel mechanism for two rotations and one movement in space, comprising: A fixed platform; A movable platform; The three-degree-of-freedom motion comprises two rotary motions around two axes of different surfaces in space and one motion along the normal direction of the fixed platform, wherein each main chain comprises a first branched chain and a second branched chain, the first end of the first branched chain and the first end of the second branched chain are connected with the spherical surface of the movable platform through equivalent spherical hinges, the second end of the first branched chain is rotationally connected with the fixed platform, and the second end of the second branched chain is rotationally connected with the fixed platform through a revolute pair; Wherein each of the first branch chains comprises; the first end of the first upper connecting rod is connected with the movable platform through the equivalent spherical hinge; The first end of the first lower connecting rod is rotationally connected with the second end of the first upper connecting rod through a first revolute pair, and the second end of the first lower connecting rod is rotationally connected with the fixed platform through a second revolute pair; Each of the second branches comprises: The first end of the second upper connecting rod is respectively connected with the first end of the first upper connecting rod and the movable platform through the equivalent spherical hinge; the first end of the second lower connecting rod is rotationally connected with the second end of the second upper connecting rod through a third revolute pair, and the second end of the second lower connecting rod is rotationally connected with the fixed platform through a fourth revolute pair.
2. The mechanism of claim 1, wherein the equivalent spherical hinge comprises: The first rotating shaft is rotationally connected with the movable platform, and the rotating axis of the first rotating shaft is perpendicular to the movable platform; the second rotating shaft is rotationally connected with the first rotating shaft, and the rotating axis of the second rotating shaft is perpendicular to the rotating axis of the first rotating shaft; And the rotating axis of the third rotating shaft is perpendicular to the rotating axis of the second rotating shaft and the axis of the first rotating shaft respectively.
3. The mechanism of claim 1, wherein the second revolute pair and the fourth revolute pair of each main branch chain are arranged in a manner comprising: The arrangement points of the second revolute pairs are uniformly distributed on the circular arc of a first circumscribing circle, and the axis of each second revolute pair is tangential to the first circumscribing circle, wherein the first circumscribing circle is a circumscribing circle formed by the connection points of each second revolute pair and the fixed platform; The arrangement points of the fourth revolute pairs are uniformly distributed on the circular arc of a second circumscribed circle, and the axis of each fourth revolute pair is tangent to the second circumscribed circle, wherein the second circumscribed circle is a circumscribed circle formed by the connection points of each fourth revolute pair and the fixed platform; the diameter of the first circumscribing circle is larger than that of the second circumscribing circle.
4. The mechanism of claim 1, wherein axes of the first revolute pair, the second revolute pair, the third revolute pair, and the fourth revolute pair in each of the main branches are parallel to each other.
5. The mechanism of claim 1, wherein the arrangement points of the equivalent spherical hinges are uniformly distributed on the circular arc of a third circumcircle of the movable platform, and the third circumcircle is a circumcircle formed by connecting points of the equivalent spherical hinges and the movable platform.
6. The mechanism of claim 1, further comprising: The power source is used for driving the second revolute pair and the fourth revolute pair in the main branched chains to enable the first lower connecting rod and the second lower connecting rod to do rotary motion relative to the customized platform respectively; wherein, two rotational movements around two axes of space different face, along a motion of fixed platform normal direction, include: The first lower connecting rod and the second lower connecting rod rotate relative to the fixed platform and respectively drive the first upper connecting rod and the second upper connecting rod to do rotary motion relative to the first lower connecting rod and the second lower connecting rod; The first upper connecting rod and the second upper connecting rod rotate relative to the first lower connecting rod and the second lower connecting rod and drive the movable platform to move in a spherical surface relative to the first upper connecting rod and the second upper connecting rod; The movable platform moves in a spherical mode relative to the first upper connecting rod and the second upper connecting rod, and simultaneously two rotary motions around two axes of different planes of space are achieved, and one moving motion along the normal direction of the fixed platform is achieved.
7. A mechanical device comprising the three degree of freedom parallel mechanism of any one of claims 1 to 6.

Description

Three-degree-of-freedom parallel mechanism with two space rotation and one space movement and mechanical device Technical Field The present disclosure relates to the field of parallel robots, and more particularly to a three-degree-of-freedom parallel mechanism with two rotations and one movement in space. Background The parallel robot has the advantages of small accumulated error, high motion precision, high response speed and the like, and plays a key role in industrial production. By virtue of the excellent characteristics, the parallel robot with less degrees of freedom can be used for scenes such as posture adjustment, precision manufacturing, medical operation and the like. The space two-to-one-shift parallel mechanism belongs to a very typical few-degree-of-freedom parallel mechanism, and is widely focused in academic and industrial fields due to the characteristics of simple structure, easy control and the like. The existing two-to-one-shift parallel mechanism is often asymmetric in structure, insufficient in rigidity, small in bearing capacity and low in fault tolerance. In the related art, a moving pair is often selected as a sliding driving pair for the two-rotation and one-movement low-freedom parallel mechanism, but the existing power source is a rotating motor, and the rotating motion of the motor can be converted into the linear motion only by additionally introducing linear mechanical structures such as a linear sliding table or a ball screw, and the introduction of the linear mechanical structures enables the parallel structure to have a certain power response delay, so that the output efficiency and the output precision of the rotating motor are reduced. Therefore, friction and gaps in the moving pair become error sources of the two-rotation one-movement parallel mechanism, transmission precision of the parallel mechanism is reduced, extra mechanical complexity of the two-rotation one-movement parallel mechanism is increased, and the whole parallel mechanism is complex. The information disclosed in the background section of the present disclosure is only for enhancement of understanding of the general background of the present disclosure and is not to be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is known to a person skilled in the art. Disclosure of Invention In view of the above, the present disclosure provides a three-degree-of-freedom parallel mechanism and a mechanical device with two-rotation and one-movement space. According to a first aspect of the present disclosure, there is provided a three degree of freedom parallel mechanism for spatial two-rotation one-movement, comprising: A fixed platform; A movable platform; The three-degree-of-freedom motion comprises two rotary motions around two axes of different surfaces in space and one motion along the normal direction of the fixed platform, wherein each main chain comprises a first branched chain and a second branched chain, the first end of the first branched chain and the first end of the second branched chain are connected with the spherical surface of the movable platform through equivalent spherical hinges, the second end of the first branched chain is rotationally connected with the fixed platform, and the second end of the second branched chain is rotationally connected with the fixed platform through a revolute pair; Wherein each of the first branch chains comprises; the first end of the first upper connecting rod is connected with the movable platform through the equivalent spherical hinge; The first end of the first lower connecting rod is rotationally connected with the second end of the first upper connecting rod through a first revolute pair, and the second end of the first lower connecting rod is rotationally connected with the fixed platform through a second revolute pair; Each of the second branches comprises: The first end of the second upper connecting rod is respectively connected with the first end of the first upper connecting rod and the movable platform through the equivalent spherical hinge; the first end of the second lower connecting rod is rotationally connected with the second end of the second upper connecting rod through a third revolute pair, and the second end of the second lower connecting rod is rotationally connected with the fixed platform through a fourth revolute pair. According to an embodiment of the present disclosure, the equivalent spherical hinge includes: The first rotating shaft is rotationally connected with the movable platform, and the rotating axis of the first rotating shaft is perpendicular to the movable platform; the second rotating shaft is rotationally connected with the first rotating shaft, and the rotating axis of the second rotating shaft is perpendicular to the rotating axis of the first rotating shaft; And the rotating axis of the third rotating shaft is perpendicular to the rotating axis of the second rotating sha