Parallel mechanism with two three-movement one-rotation movement modesTechnical Field
The invention belongs to the technical field of robots, and relates to a parallel mechanism with two three-movement one-rotation movement modes.
Background
The parallel robot mechanism is in a space multi-degree-of-freedom multi-ring closed chain form. Since the eighties of the last century, the parallel mechanism has the characteristics of high rigidity, large bearing capacity, small accumulated error, good dynamic characteristic, compact structure and the like, and is widely applied to the industrial fields of virtual axis machine tools, micro-motion operation tables, motion simulators, multi-dimensional force sensors and the like. The parallel mechanism has 2, 3, 4, 5 or 6 degrees of freedom, at present, the parallel mechanism with 6 degrees of freedom is researched more comprehensively and deeply, but the reduction of the degrees of freedom of the parallel mechanism enables the mechanism structure to be simpler, and the manufacturing and control cost to be relatively lower, so that the parallel robot with less degrees of freedom has unique advantages under the condition of meeting the expected working requirement.
The parallel mechanism with multiple motion modes has the characteristic of motion bifurcation under the singular configuration of the mechanism, and can realize multiple motion modes through fewer driving pairs and branched chains, thereby being suitable for different work requirements. And the movement mode of the mechanism is changed without reassembling the mechanism, and the movement mode is high in changing speed and simple and convenient in process. For example, under a certain light load working condition, the robot end effector is required to realize actions such as positioning and grabbing at high speed and high acceleration, and at the moment, the parallel robot can better exert the advantages of the robot end effector.
At present, three-shift one-rotation (3T1R) four-degree-of-freedom parallel mechanisms with two motion modes are rare, and the parallel mechanism of the present invention has a fixed axis of rotational freedom in one motion mode of three-shift one-rotation (3T1R) and a variable axis of rotational freedom in the other motion mode of three-shift one-rotation. The novel parallel mechanism has a certain application prospect in the fields of motion simulation, machine assembly, sorting and grabbing, parallel machine tools and the like.
Disclosure of Invention
The invention aims to provide a parallel mechanism with two three-movement one-rotation motion modes, which solves the problem that the existing four-freedom parallel mechanism is single in motion mode, cannot meet the requirement of multiple purposes of one machine in industry and is inconvenient to use.
The parallel mechanism comprises a movable platform and a fixed platform, wherein the movable platform is connected with the fixed platform through a first branched chain, a second branched chain, a third branched chain and a fourth branched chain respectively, the first branched chain and the third branched chain are oppositely arranged at two opposite corners of the bottom surface of the movable platform, the second branched chain and the fourth branched chain are oppositely arranged at the other two opposite corners of the bottom surface of the movable platform, the structures of the first branched chain and the third branched chain are similar, the positions of driving pairs are different, the structures of the second branched chain and the fourth branched chain are similar, and the positions of the driving pairs are different;
the first branch chain comprises a sliding pair P11A first connecting rod and a sliding pair P12A second connecting rod and a sliding pair P13A third connecting rod and a revolute pair R14And a revolute pair R15;
The second branch chain comprises a moving pair P21Eighth connecting rod, sliding pair P22A seventh connecting rod and a sliding pair P23A sixth connecting rod and a revolute pair R24A fifth connecting rod and a revolute pair R25。
Yet another feature of the present invention is that,
the first branched chain comprises a sliding pair P connected with the fixed platform11Of moving pair P11Sequentially connected with a first connecting rod and a sliding pair P12A second connecting rod and a sliding pair P13A third connecting rod and a revolute pair R14And a revolute pair R15Rotational pair R14And a revolute pair R15Connected to form a universal hinge and a revolute pair R15Is connected with the movable platform.
Sliding pair P11And a sliding pair P12And P of moving pair13The moving directions of the two pairs are mutually vertical, and the revolute pair R14The axis of the rotating shaft and the sliding pair P11Are parallel to the moving direction of the rotating pair R15The axis of the rotating shaft and the sliding pair P12Are parallel to each other.
The second branched chain comprises a sliding pair P connected with the fixed platform21Of moving pair P21The eighth connecting rod and the sliding pair P are connected in sequence22A seventh connecting rod and a sliding pair P23A sixth connecting rod and a revolute pair R24A fifth connecting rod and a revolute pair R25Rotational pair R24The axis of the rotating shaft and the revolute pair R25The included angle of the axes of the rotating shafts is 135 degrees, and the revolute pair R25Is connected to the movable platform.
Sliding pair P21And a sliding pair P22And a sliding pair P23The moving directions of the two pairs are mutually vertical, and the revolute pair R24The axis of the rotating shaft and the sliding pair P21Are parallel to each other.
The fifth connecting rod is an arc connecting rod, radian and revolute pair R24The axis of the rotating shaft and the revolute pair R25The included angles of the axes of the rotating shafts are the same.
The parallel mechanism has the beneficial effects that the parallel mechanism with two three-movement one-rotation motion modes solves the problems that the existing four-freedom-degree parallel mechanism is single in motion mode, cannot meet the requirement of multiple purposes of one machine in industry and is inconvenient to use, and the structure of the mechanism is simple. The parallel mechanism of the invention connects the movable platform and the fixed platform by arranging four branched chains, and the branched chains use a moving pair and a rotating pair, and form a universal hinge by two directly connected rotating pairs, thus realizing the flexible movement of the branched chains to all directions; the parallel mechanism is easy to manufacture integrally, simple to control and good in flexibility, and particularly suitable for spraying paint on the automobile bumpers, and the mechanism can adapt to bumpers of different shapes during spraying, so that the production efficiency is improved.
Drawings
FIG. 1 is a schematic view of the instantaneous degree of freedom configuration of a parallel mechanism 3T2R of the present invention having two modes of three-shift-one-rotation motion;
FIG. 2 is a schematic view of a parallel mechanism of the present invention in a fixed-axis-of-rotation mode with two modes of three-shift-one-rotation motion;
fig. 3 is a schematic view of the variable movement mode of the rotation axis of the parallel mechanism with two three-shift-one rotation movement modes according to the present invention.
In the figure, 1, a first connecting rod, 2, a second connecting rod, 3, a third connecting rod, 4, a movable platform, 5, a fifth connecting rod, 6, a sixth connecting rod, 7, a seventh connecting rod, 8, an eighth connecting rod and 9, a fixed platform.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The parallel mechanism with two three-movement one-rotation movement modes is characterized by comprising a movable platform 4 and a fixed platform 9, wherein the movable platform 4 is connected with the fixed platform 9 through a first branched chain, a second branched chain, a third branched chain and a fourth branched chain respectively, and four corners of the movable platform 4 are defined as A respectively1、A2、A3And A4The first branched chain and the third branched chain are oppositely arranged at two pairs of corners of the bottom surface of the movable platform 4, the second branched chain and the fourth branched chain are oppositely arranged at the other two pairs of corners of the bottom surface of the movable platform 4, the first branched chain and the third branched chain have similar structures and different driving pair positions, and the second branched chain and the fourth branched chain have similar structures and different driving pair positions;
the first branch chain comprises a sliding pair P11A first connectingrod 1 and a sliding pair P12A second connectingrod 2 and a sliding pair P13A third connectingrod 3 and a revolute pair R14And a revolute pair R15;
The second branch chain comprises a moving pair P21Eighth connectingrod 8 and sliding pair P22A seventh connectingrod 7 and a sliding pair P23A sixth connecting rod 6 and a revolute pair R24A fifth connecting rod 5 and a revolute pair R25;
Sliding pair P11And a sliding pair P21Is perpendicular to the moving direction of the sliding pair P21And a sliding pair P22Is perpendicular to the moving direction of the sliding pair P13And a sliding pair P23Is vertical.
The first branch chain comprises and is fixedKinematic pair P connected with table 911Of moving pair P11Sequentially connected with a first connectingrod 1 and a sliding pair P12A second connectingrod 2 and a sliding pair P13A third connectingrod 3 and a revolute pair R14And a revolute pair R15Rotational pair R14And a revolute pair R15Connected to form a universal hinge and a revolute pair R15Is connected to the bottom surface A of the movable platform 41To (3).
Sliding pair P11And a sliding pair P12And P of moving pair13The moving directions of the first connectingrod 1, the second connectingrod 2 and the third connectingrod 3 are mutually vertical in pairs, the first connecting rod, the second connecting rod and the third connecting rod are all in T shape, and a moving pair P is arranged11The movable driving pair is connected with a driving motor; revolute pair R14The axis of the rotating shaft and the sliding pair P11Are parallel to the moving direction of the rotating pair R15The axis of the rotating shaft and the sliding pair P12Are parallel to each other.
The second branch chain comprises a sliding pair P connected with the fixed platform 921Of moving pair P21The eighth connectingrod 8 and the sliding pair P are connected in sequence22A seventh connectingrod 7 and a sliding pair P23A sixth connecting rod 6 and a revolute pair R24A fifth connecting rod 5 and a revolute pair R25Rotational pair R24The axis of the rotating shaft and the revolute pair R25The included angle of the axes of the rotating shafts is 135 degrees, and the revolute pair R25Is connected to the bottom surface A of the movable platform 42To (3).
Sliding pair P in third branch13Is connected with a driving motor.
Sliding pair P in fourth branch23Is connected with a driving motor.
Sliding pair P21And a sliding pair P22And a sliding pair P23The moving directions of the first connectingrod 8, the seventh connectingrod 7 and the sixth connecting rod 6 are mutually vertical in pairs, the eighth connecting rod, the seventh connecting rod and the sixth connecting rod are all in T shape, and a sliding pair P21The driving motor is connected for moving the driving pair, and the moving pair P23As an auxiliary moving drive pair, is connected with a drive motor and a revolute pair R24The axis of the rotating shaft and the sliding pair P21Are parallel to each other.
The fifth connecting rod 5 is an arc-shaped connecting rod, radian and revolute pair R24Axis and rotation of the rotating shaftKinematic pair R25The included angles of the axes of the rotating shafts are the same.
In the parallel mechanism with two three-movement one-rotation movement modes of the invention, under the mechanism configuration shown in figure 1, a moving pair P11Along the Y-axis direction, and a sliding pair P12Along the X-axis, and a sliding pair P13Along the Z-axis direction, a revolute pair R14The axis of the rotating shaft is along the Y-axis direction, and the rotating pair R15The axis of the rotating shaft is along the X-axis direction; sliding pair P21Along the X-axis, and a sliding pair P22Along the Y-axis direction, and a sliding pair P23Along the Z-axis direction, a revolute pair R24The axis of the rotating shaft is along the Y-axis direction, and the rotating pair R25Axis of rotation of R24Is 135 deg..
In the configuration of the mechanism shown in fig. 1, which has a 3T2R motion pattern, but which is instantaneous, the mechanism has three degrees of freedom of movement, the axes of rotation of the two degrees of freedom of rotation forming the XOY plane. Controlling the sliding pair P in the first branch chain11A sliding pair P in the second branch chain21A sliding pair P in the third branch chain13A sliding pair P in the second branch chain23A sliding pair P in the fourth branch chain23The end of the fourth branched chain moves towards the negative direction of the Z axis, the end of the second branched chain moves towards the positive direction of the Z axis, so that the movable platform 4 rotates around the X axis, the mechanism moves to the mechanism configuration shown in fig. 2, the mechanism has a 3T1R movement mode, and the rotation axis is fixed and is along the direction of the X axis. In this configuration, the revolute pair R in the first branch14And a revolute pair R in the third branched chain14And a revolute pair R in the second branched chain24And revolute pair R in the fourth branch chain24Parallel to control the moving pair P in the first branch chain11A sliding pair P in the second branch chain21A sliding pair P in the third branch chain13A sliding pair P in the fourth branch chain23Control of the movement pattern may be achieved.
In the configuration of the mechanism shown in FIG. 1, the kinematic pair P in the first branch chain is controlled11A sliding pair P in the second branch chain21And a sliding pair P23A sliding pair P in the third branch chain13A sliding pair P in the fourth branch chain23So that the movable platform 4 rotates around the axis parallel to the Y axis, and then the mechanism enters another 3T1R motion mode, the instantaneous rotating shaft axis of the 3T1R motion mode is changed, and the change of the rotating shaft axis is similar to the instantaneous rotating shaft axis of the connecting rod of the spherical 4R mechanism, and the rotating shaft axis rotates around the rotating center and changes continuously. In this configuration, the revolute pair R in the first branch chain14The axis of the rotating shaft and a revolute pair R in the third branched chain14The axes of the rotating shafts are parallel, and the revolute pair R in the second branched chain24The axis of the rotating shaft and a revolute pair R in the fourth branched chain24The axes of the rotating shafts are parallel. Under the motion mode, the sliding pair P in the first branch chain is controlled11A sliding pair P in the second branch chain21A sliding pair P in the third branch chain13And a mobile pair P in the fourth branch23Control of the movement pattern may be effected.
The parallel mechanism of the invention connects the movable platform and the fixed platform by arranging four branched chains, and the branched chains use a moving pair and a rotating pair, and form a universal hinge by two directly connected rotating pairs, thus realizing the flexible movement of the branched chains to all directions; the parallel mechanism is easy to manufacture integrally, simple to control and good in flexibility, and particularly suitable for spraying paint on automobile bumpers, the mechanism can adapt to bumpers of different shapes during spraying, and further production efficiency is improved.