Single-input two-translational-one-rotational parallel mechanism with lockable mobile pairs

Abstract

The application provides a single-active-input two-rotation-one-translation parallel mechanism containing a lockable moving pair, relates to the field of parallel mechanisms, and comprises a fixed platform, a movable platform, a passive branch chain and an active branch chain, the passive branch chain and the active branch chain are arranged between the fixed platform and the movable platform, and the passive branch chain comprises a rotating pair, a connecting piece, a first hook hinge, a guide rod, an end cover, an outer sleeve, an inner sleeve and a second hook hinge. The moving of the passive branch chain is realized through the screwing of the inner sleeve and the outer sleeve, the interconversion between the following state and the locking state of the moving pair is realized through the relative rotation between the end cover and the guide rod, the structure is simple, the stability is high, and the operation is more convenient and efficient, the driving pair of the active branch chain is taken as a single active driving, the passive adaptive cooperation of the passive branch chain is realized, the movable platform can realize three-degree-of-freedom motion of lifting, yawing and pitching, the overall rigidity of the mechanism is enhanced through reasonable arrangement, and greater bearing capacity is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of parallel mechanisms, and in particular relates to a single active input two-rotation one-transfer parallel mechanism containing a lockable moving pair. Background Art

[0002] Compared with the widely used six-degree-of-freedom parallel mechanism, the low-degree-of-freedom parallel mechanism has higher applicability in industrial automation fields such as precision assembly, welding and spraying, as well as medical fields such as minimally invasive surgical robots and rehabilitation equipment.

[0003] After searching, it was found that the Chinese patent with patent number CN201910833742.5 discloses a large-angle non-coplanar two-rotation and one-translation redundant drive parallel mechanism, including a fixed platform, a moving platform and two groups of first branch chain components and two groups of second branch chain components. The moving pair in each group of branch chain components is a driving pair, that is, under the action of 6 drives, two rotations around the moving platform plane and the fixed platform plane and two degrees of freedom of movement perpendicular to the moving platform direction are realized.

[0004] The Chinese patent No. 201310606428.6 provides a kinematic pair for eliminating the accompanying displacement of the mechanism, which has the function of eliminating the accompanying displacement of the mechanism. The accompanying displacement elimination mechanism is composed of four parallelogram mechanisms, which has many components and is difficult to install.

[0005] However, the above-mentioned existing technologies all have the problem that the movable joint cannot be locked during operation, resulting in an inability to accurately fix the position after the position is confirmed, which reduces their working efficiency. Therefore, it is necessary to propose a single active input two-rotation one-shift parallel mechanism with a lockable movable joint, which can realize single active input to adjust the posture and lock the posture through a passive branch chain. Summary of the Invention

[0006] In response to the problems existing in the prior art, the present invention provides a single active input two-turn and one-shift parallel mechanism containing a lockable moving pair. The present invention realizes the movement of the passive branch chain through the spiral cooperation of the inner sleeve and the outer sleeve, and realizes the mutual conversion of the following and locking states of the moving pair through the relative rotation between the end cover and the guide rod. It has high stability and is more convenient and efficient to operate. By using the driving pair of the active branch chain as a single active drive and the passive adaptive cooperation of the passive branch chain, the dynamic platform can realize the three-degree-of-freedom movement of lifting, swaying and pitching. Through reasonable arrangement, the overall rigidity of the mechanism is enhanced to achieve greater bearing capacity.

[0007] The present invention provides a single active input two-turn one-shift parallel mechanism containing a lockable movable pair, which includes a fixed platform, a movable platform, a passive branch chain and an active branch chain, the movable platform is arranged above the fixed platform, and the passive branch chain and the active branch chain are both arranged between the fixed platform and the movable platform; the passive branch chain includes a ball pair, a movable pair, a connecting piece and a second Hooke's joint, the ball pair includes a rotating pair and a first Hooke's joint, the movable pair includes a guide rod, an end cover, an outer sleeve and an inner sleeve, the first end of the rotating pair is connected to the movable platform, the first end of the first Hooke's joint is connected to the second end of the rotating pair through the connecting piece, the first end of the guide rod is connected to the second end of the first Hooke's joint, the first end of the end cover is rotatably connected to the second end of the guide rod, the first end of the outer sleeve is connected to the second end of the end cover, the first end of the inner sleeve is spirally connected to the second end of the outer sleeve, and the first end of the second Hooke's joint is connected to the second end of the inner sleeve , the fixed platform is connected to the second end of the second Hooke's hinge; the active branch chain includes a third Hooke's hinge, a driving pair and a driving pair connecting member, the first end of the third Hooke's hinge is connected to the moving platform, the first end of the driving pair is connected to the second end of the third Hooke's hinge, and the second end of the driving pair is connected to the fixed platform through the driving pair connecting member; the moving pair has a following state and a locked state, and the two states are transformed into each other; the first end of the end cover is symmetrically provided with two arc grooves and two arc flanges, and the second end of the guide rod is provided with an annular flange that cooperates with the arc groove or flange, when the annular flange of the guide rod cooperates with the arc groove of the end cover, the guide rod can move on the end cover, the outer sleeve and the inner sleeve, at this time the moving pair is in the following state; when the arc flange of the end cover is located between the two pairs of annular flanges of the guide rod, the guide rod is fixed to the end cover, the outer sleeve and the inner sleeve, and at this time the moving pair is in the locked state.

[0008] Preferably, the passive branch chains are provided with three groups of passive branch chains, and the three groups of passive branch chains are respectively arranged between the fixed platform and the movable platform at equal intervals at a circumference of 120°, and the two ends of the active branch chains are respectively connected to the center of the fixed platform and the movable platform.

[0009] Preferably, the guide rod is a hollow cylindrical structure, the length of the guide rod is greater than the length of the inner sleeve, and its diameter is smaller than the inner diameter of the inner sleeve, a first through hole is provided on the first end side wall of the guide rod, and a second through hole is provided on the second end side wall of the inner sleeve.

[0010] Preferably, the distance between the two arc-shaped flanges of the end cover is equal to the distance between the two pairs of annular flanges of the guide rod.

[0011] Preferably, an internal thread is provided on the inner side of the second end of the outer sleeve, an external thread is provided on the outer side of the first end of the inner sleeve, and the length of the external thread is greater than the length of the internal thread.

[0012] Preferably, the passive branch chain is a UPS structure, and the active branch chain is a PU structure.

[0013] Preferably, the two rotations and one shift include a rotation in a first rotation direction and a second rotation direction and a movement direction, the first rotation direction and the second rotation direction are always spatially skewed and perpendicular; the movement direction is perpendicular to the first rotation direction and the second rotation direction respectively; the positions of the first rotation direction and the second rotation direction can rotate around a fixed axis.

[0014] Preferably, the axis of the moving platform is parallel to the axis of the rotating pair, the axis of the outer rotating pair of the first Hooke's joint is perpendicular to the axis of the moving platform, the axis of the outer rotating pair of the second Hooke's joint is perpendicular to the axis of the fixed platform, and the axis of the outer rotating pair of the first Hooke's joint is perpendicular to the axis of the outer rotating pair of the second Hooke's joint.

[0015] Preferably, the axes of the guide rod, end cover, outer sleeve and inner sleeve coincide with each other, the axes of the moving pair of the passive branch chain are respectively perpendicular to the axes of the inner rotating pairs of the first Hooke's joint and the second Hooke's joint, the axes of the driving pair of the active branch chain are respectively perpendicular to the axes of the moving platform and the fixed platform, and are perpendicular to the axis of the inner rotating pair of the third Hooke's joint.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] (1) The single active input two-turn one-shift parallel mechanism with a lockable movable pair of the present invention realizes the movement of the passive branch chain through the spiral cooperation of the inner sleeve and the outer sleeve. At the same time, the mutual conversion between the follow-up and locking states of the movable pair is realized through the relative rotation between the end cover and the guide rod. It has a simple structure, high stability, and is more convenient and efficient to operate.

[0018] (2) The single active input two-rotation one-transfer parallel mechanism with a lockable moving pair of the present invention can realize the three-degree-of-freedom movement of the moving platform, namely, lifting, swaying and pitching, by using the driving pair of the active branch chain as a single active drive and the passive adaptability of the passive branch chain.

[0019] (3) The present invention contains a single active input two-turn one-shift parallel mechanism with a lockable moving pair, which is composed of three passive branches and one active branch. The three passive branches are distributed around the periphery at equal intervals, and the active branch coincides with the central axis of the mechanism, thereby enhancing the overall rigidity of the mechanism and achieving greater bearing capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the overall structure of the single active input two-rotation one-transmission parallel mechanism with a lockable moving pair according to the present invention;

[0021] Figure 2 It is a schematic top view of the overall structure of the present invention;

[0022] Figure 3 Schematic diagram of the passive branched chain structure of the present invention;

[0023] Figure 4 Schematic diagram of the structure of the active branch chain of the present invention;

[0024] Figure 5 A simplified structural diagram of the lockable movable pair of the present invention;

[0025] Figure 6 This is a schematic structural diagram of the guide rod in the lockable movable pair of the present invention;

[0026] Figure 7 This is a schematic structural diagram of the lockable movable middle end cover of the present invention;

[0027] Figure 8 It is a structural schematic diagram of the inner and outer sleeves of the lockable movable pair of the present invention;

[0028] Figure 9 It is a structural schematic diagram of the inner sleeve in the lockable movable pair of the present invention;

[0029] Figure 10 It is a schematic cross-sectional view of the structure of the lockable movable pair when the passive branch of the present invention is in the follow-up state;

[0030] Figure 11 It is a schematic cross-sectional view of the structure of the lockable movable pair when the passive branch of the present invention is in a locked state.

[0031] Main reference numerals:

[0032] Fixed platform 1, moving platform 2, passive branch chain 3, revolving pair 31, connecting piece 32, first Hooke's hinge 33, guide rod 34, annular flange 341, end cover 35, arcuate groove 351, arcuate flange 352, outer sleeve 36, inner sleeve 37, second Hooke's hinge 38, active branch chain 4, third Hooke's hinge 41, driving pair 42, driving pair connecting piece 43. DETAILED DESCRIPTION

[0033] To fully describe the technical content, objectives and effects of the present invention, the following will be described in detail with reference to the accompanying drawings.

[0034] like Figure 1 and Figure 2As shown, the present invention provides a single active input two-rotation one-transfer parallel mechanism with a lockable moving pair, which includes a fixed platform 1, a moving platform 2, a passive branch chain 3 and an active branch chain 4. The moving platform 2 is arranged above the fixed platform 1, and the passive branch chain 3 and the active branch chain 4 are arranged between the fixed platform 1 and the moving platform 2; the passive branch chain 3 is a UPS structure, and the S pair is composed of a U+R structure; the active branch chain 4 is a PU structure; wherein U represents a Hooke's joint, P represents a moving pair, S represents a ball pair, and R represents a rotating pair.

[0035] The axis of the moving platform 2 is parallel to the axis of the revolving pair 31. The axis of the outer revolving pair of the first Hooke's joint 33 is perpendicular to the axis of the moving platform 2. The axis of the outer revolving pair of the second Hooke's joint 38 is perpendicular to the axis of the fixed platform 1. The axis of the outer revolving pair of the first Hooke's joint 33 is not perpendicular to the axis of the outer revolving pair of the second Hooke's joint 38. The axis of the driving pair 42 of the active branch chain 4 is perpendicular to the axes of the moving platform 2 and the fixed platform 1, respectively, and is also perpendicular to the axis of the inner revolving pair of the third Hooke's joint 41.

[0036] The passive branch chain 3 is provided with three groups of passive branch chains, and the three groups of passive branch chains 3 are respectively arranged between the fixed platform 1 and the movable platform 2 at equal intervals of 120° around the circumference. The two ends of the active branch chain 4 are respectively connected to the center of the fixed platform 1 and the movable platform 2. The parallel mechanism can realize rotation in two directions and movement in one direction. Its first rotation direction and the second rotation direction are always spatially skewed and perpendicular; its movement direction is perpendicular to the first rotation direction and the second rotation direction; the position and direction of the first rotation direction and the second rotation direction are fixed, that is, the position of the first rotation direction and the second rotation direction can always rotate around the fixed axis.

[0037] like Figures 3 to 9 As shown, the passive branch chain 3 includes a revolving pair 31, a connecting member 32, a first Hooke's hinge 33, a guide rod 34, an end cover 35, an outer sleeve 36, an inner sleeve 37 and a second Hooke's hinge 38. The first end of the revolving pair 31 is connected to the moving platform 2, the first end of the first Hooke's hinge 33 is connected to the second end of the revolving pair 31 through the connecting member 32, the first end of the guide rod 34 is connected to the second end of the first Hooke's hinge 33, the first end of the end cover 35 is rotatably connected to the second end of the guide rod 34, the first end of the outer sleeve 36 is connected to the second end of the end cover 35, the first end of the inner sleeve 37 is spirally connected to the second end of the outer sleeve 36, the first end of the second Hooke's hinge 38 is connected to the second end of the inner sleeve 37, and the fixed platform 1 is connected to the second end of the second Hooke's hinge 38.

[0038] The active branch chain 4 includes a third Hooke's joint 41, a driving pair 42 and a driving pair connecting member 43. The first end of the third Hooke's joint 41 is connected to the moving platform 2, the first end of the driving pair 42 is connected to the second end of the third Hooke's joint 41, and the second end of the driving pair 42 is connected to the fixed platform 1 through the driving pair connecting member 43.

[0039] The ball pair of the passive branch chain 3 includes a revolute pair 31 and a first Hooke's joint 33 , and the moving pair of the passive branch chain 3 includes a guide rod 34 , an end cover 35 , an outer sleeve 36 and an inner sleeve 37 .

[0040] The axes of the guide rod 34 , the end cover 35 , the outer sleeve 36 and the inner sleeve 37 coincide with each other, and the axes of the moving pair of the passive branch chain 3 are perpendicular to the axes of the inner rotating pairs of the first Hooke's hinge 33 and the second Hooke's hinge 38 .

[0041] Two arcuate grooves 351 and two arcuate flanges 352 are symmetrically provided at the first end of the end cover 35, and an annular flange 341 connected to the arcuate groove 351 or the flange 352 is provided at the second end of the guide rod 34. The distance between the two arcuate flanges 352 is equal to the distance between the two pairs of annular flanges 341, ensuring that the moving pair can be converted to a locked state in the following state.

[0042] The guide rod 34 is a hollow cylindrical structure. The length of the guide rod 34 is greater than the length of the inner sleeve 37, and its diameter is smaller than the inner diameter of the inner sleeve 37. The first end of the guide rod 34 is provided with a first through hole, and the first through hole is connected to the first Hooke's hinge 33. The second end of the inner sleeve 37 is provided with a second through hole, and the second through hole is connected to the second Hooke's hinge 38. The inner side of the second end of the outer sleeve 36 is provided with an internal thread, and the outer side of the first end of the inner sleeve 37 is provided with an external thread, and the length of the external thread is greater than the length of the internal thread.

[0043] like Figure 10 and Figure 11 As shown, the moving pair of the passive branch chain 3 has a following state and a locking state, and the two states are transformed into each other. When the annular flange 341 of the guide rod 34 cooperates with the arc-shaped groove 351 of the end cover 35, the guide rod 34 can move on the end cover 35, the outer sleeve 36 and the inner sleeve 37, and the moving pair is in the following state; when the arc-shaped flange 352 of the end cover 35 is located between the two pairs of annular flanges 341 of the guide rod 34, the guide rod 34 is fixed to the end cover 35, the outer sleeve 36 and the inner sleeve 37, and the moving pair is in the locking state.

[0044] In actual use, the guide rod 34 is rotated so that its annular flange 341 mates with the arcuate groove 351 of the end cap 35. The guide rod 34 can now move relative to the end cap 35, outer sleeve 36, and inner sleeve 37. The driving pair 42 of the active branch chain 4 is then activated to adjust the position of the moving platform 2. When the moving platform 2 reaches the target position, the guide rod 34 is rotated so that the arcuate flange of the end cap 35 is positioned between the two pairs of annular flanges 341 of the guide rod 34. The guide rod 34 is now fixed to the end cap 35, outer sleeve 36, and inner sleeve 37, thereby switching the moving pair to a locked state and achieving the adjusted distance of the passive branch chain 3.

[0045] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A single active input two-rotation one-transmission parallel mechanism with a lockable moving pair, characterized in that: It includes a fixed platform, a moving platform, a passive branch chain and an active branch chain, wherein the moving platform is arranged above the fixed platform, and the passive branch chain and the active branch chain are both arranged between the fixed platform and the moving platform; The passive branch chain includes a ball pair, a movable pair, a connecting piece and a second Hooke's joint, the ball pair includes a revolving pair and a first Hooke's joint, the revolving pair includes a guide rod, an end cover, an outer sleeve and an inner sleeve, the first end of the revolving pair is connected to the moving platform, the first end of the first Hooke's joint is connected to the second end of the revolving pair through the connecting piece, the first end of the guide rod is connected to the second end of the first Hooke's joint, the first end of the end cover is rotatably connected to the second end of the guide rod, the first end of the outer sleeve is connected to the second end of the end cover, the first end of the inner sleeve is spirally connected to the second end of the outer sleeve, the first end of the second Hooke's joint is connected to the second end of the inner sleeve, and the fixed platform is connected to the second end of the second Hooke's joint; The active branch chain includes a third Hooke's joint, a driving pair and a driving pair connecting member, wherein the first end of the third Hooke's joint is connected to the moving platform, the first end of the driving pair is connected to the second end of the third Hooke's joint, and the second end of the driving pair is connected to the fixed platform via the driving pair connecting member; The movable pair has a following state and a locking state, and the two states are transformed into each other; two arc-shaped grooves and two arc-shaped flanges are symmetrically provided on the first end of the end cover, and an annular flange is provided on the second end of the guide rod to cooperate with the arc-shaped groove or the flange. When the annular flange of the guide rod cooperates with the arc-shaped groove of the end cover, the guide rod can move on the end cover, the outer sleeve and the inner sleeve, and the movable pair is in the following state; when the arc-shaped flange of the end cover is located between the two pairs of annular flanges of the guide rod, the guide rod is fixed to the end cover, the outer sleeve and the inner sleeve, and the movable pair is in the locking state.

2. The single active input two-rotation one-shift parallel mechanism with a lockable moving pair according to claim 1, characterized in that: The passive branches are configured as three groups of passive branches, which are arranged between the fixed platform and the moving platform at equal intervals around the circumference of 120°. The two ends of the active branches are connected to the centers of the fixed platform and the moving platform respectively.

3. The single active input two-rotation one-shift parallel mechanism with a lockable moving pair according to claim 1, characterized in that: The guide rod is a hollow cylindrical structure. The length of the guide rod is greater than the length of the inner sleeve, and the diameter of the guide rod is smaller than the inner diameter of the inner sleeve. A first through hole is provided on the first end side wall of the guide rod, and a second through hole is provided on the second end side wall of the inner sleeve.

4. The single active input two-rotation one-shift parallel mechanism with a lockable moving pair according to claim 1, characterized in that: The distance between the two arc-shaped flanges of the end cover is equal to the distance between the two pairs of annular flanges of the guide rod.

5. The single active input two-rotation one-transfer parallel mechanism with a lockable moving pair according to claim 1, characterized in that: An internal thread is provided on the inner side of the second end of the outer sleeve, and an external thread is provided on the outer side of the first end of the inner sleeve, and the length of the external thread is greater than the length of the internal thread.

6. The single active input two-rotation one-transmission parallel mechanism with a lockable moving pair according to claim 1, characterized in that: The passive branch chain is a UPS structure, and the active branch chain is a PU structure.

7. The single active input two-rotation one-transmission parallel mechanism with a lockable moving pair according to claim 1, characterized in that: The two rotations and one shift include a rotation in a first rotation direction and a second rotation direction and a movement direction, wherein the first rotation direction and the second rotation direction are always skewed and perpendicular to each other in space; the movement direction is perpendicular to the first rotation direction and the second rotation direction respectively; the positions of the first rotation direction and the second rotation direction can rotate around a fixed axis.

8. The single active input two-rotation one-transmission parallel mechanism with a lockable moving pair according to claim 1, characterized in that: The axis of the moving platform is parallel to the axis of the rotating pair, the axis of the outer rotating pair of the first Hooke's joint is perpendicular to the axis of the moving platform, the axis of the outer rotating pair of the second Hooke's joint is perpendicular to the axis of the fixed platform, and the axis of the outer rotating pair of the first Hooke's joint is perpendicular to the axis of the outer rotating pair of the second Hooke's joint in different planes.

9. The single active input two-rotation one-transfer parallel mechanism with a lockable movable pair according to claim 1, characterized in that: The axes of the guide rod, end cover, outer sleeve and inner sleeve coincide with each other, the axes of the moving pair of the passive branch chain are respectively perpendicular to the axes of the inner rotating pairs of the first and second Hooke's joints, the axes of the driving pair of the active branch chain are respectively perpendicular to the axes of the moving platform and the fixed platform, and are perpendicular to the axis of the inner rotating pair of the third Hooke's joint.

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