A six-degree-of-freedom large-stroke uncoupling large hollow series-parallel piezoelectric micro-motion platform includes a base, a movable platform top, a second platform and a first platform, wherein a first guide unit, a second guide unit, a third guide unit, a fourth guide unit, a fifth guide unit and a sixth guide unit are respectively connected in sequence to the second platform and the first platform; the first guide unit is internally provided with a first drive unit, the second guide unit is internally provided with a second drive unit, and the third guide unit is internally provided with a third drive unit; and the base is provided with a fourth drive unit, a fifth drive unit, a sixth drive unit and a seventh drive unit, the fifth drive unit is provided below the second drive unit, and the sixth drive unit is provided below the third drive unit.

CROSS REFERENCE TO THE RELATED APPLICATIONS

This application is based upon and claims priority to Chinese Patent Application No. 201910092067.5, filed on Jan. 30, 2019, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention belongs to the field of nano-positioning technology, and relates to a micro-displacement mechanism in a nano-positioning system, in particular to a six-degree-of-freedom large-stroke uncoupling large hollow series-parallel piezoelectric micro-motion platform.

BACKGROUND

Piezoelectric micro-motion platforms are micro-displacement mechanisms for transferring displacement and force through a flexible mechanism that can generate elastic deformation under the drive of a piezoelectric actuator. Since the piezoelectric micro-motion platforms have no hinges and bearings, no assembly is needed, no transmission gap exists, and no friction and wear occur. Since the piezoelectric micro-motion platforms are driven by piezoelectric actuators, the displacement resolution can reach nanometer level, the response time can reach millisecond level, the stiffness is large, the size is small, and the load-bearing capacity is strong. Accordingly, the piezoelectric micro-motion platforms are widely used in the technical fields that need micron/nano-positioning, such as precision machining and testing, optical fiber butting, micro-part assembly, and cell micro-manipulation. For example, in the precision and ultra-precision machining, micro-feeding of cutters or compensation of machining errors can be achieved. In the precision measurement, fine adjustment of sensors can be achieved. In scanning probe microscopes, combined with micro-scanning probes, the measurement of micro-structure morphology can be achieved. In the optical fiber butting, precise alignment of two optical fibers with a diameter of several micrometers to dozens of micrometers can be achieved. In the assembly of MEMS (microelectromechanical system), combined with micro clamps, micro shafts and micro gears can be assembled into micro components; and in biological engineering, combined with micro-impact probes, corresponding constituents can be injected into or extracted from cells.

Existing six-degree-of-freedom (movable along x, y, and z directions and rotatable about x, y, and z axes) piezoelectric micro-motion platforms are mostly based on the Stewart parallel platform structure, which is implemented by connecting a movable platform to a fixed platform via six links that realize the driving function. In this implementation, the platform has a high rigidity and fast response, but also has the following disadvantages: due to the long links, the movable platform is far away from the fixed platform, which makes the platform structure huge and not compact; since no displacement amplification mechanism is used, the platform has a small displacement stroke; and the kinematics solution of and motion control over the movable platform are extremely complicated because when same moves in one of the directions, coupled movements in the other two directions will occur, and when same rotates about one of the axes, coupled angular rotations about the other two axes will occur.

SUMMARY

In view of the state of the art, the technical problem to be solved by the present invention is to provide a six-degree-of-freedom large-stroke uncoupling large hollow series-parallel piezoelectric micro-motion platform which has a simple and compact structure, a large working platform top, a large displacement stroke, no displacement coupling and a high inherent frequency, and is easily integrated with displacement sensors.

The technical solution adopted by the present invention to solve the above technical problems is: a six-degree-of-freedom large-stroke uncoupling large hollow series-parallel piezoelectric micro-motion platform, which comprises a base and a movable platform top which is provided above the base and forms a gap therewith; wherein a second platform is provided between the movable platform top and the base and forms gaps therewith; a first platform, which is screwed to the movable platform top, is provided at the center of the second platform and forms a gap therewith; the first platform comprises a first edge, a second edge, a third edge and a fourth edge which are arranged sequentially perpendicular to each other in a counterclockwise direction of the first platform; a first guide unit capable of elastic deformation is connected between the second platform and the first edge; a second guide unit and a third guide unit capable of elastic deformation are respectively connected between the second platform and the second edge; a fourth guide unit capable of elastic deformation is connected between the second platform and the third edge; a fifth guide unit and a sixth guide unit capable of elastic deformation are respectively connected between the second platform and the fourth edge; the first guide unit is internally provided with a first drive unit capable of extending and retracting in the direction of the first platform, the second guide unit is internally provided with a second drive unit capable of extending and retracting in the direction of the first platform, and the third guide unit is internally provided with a third drive unit capable of extending and retracting in the direction of the first platform; and

the base is provided with a fourth drive unit, a fifth drive unit, a sixth drive unit and a seventh drive unit which perpendicularly extend and retract to act on the second platform. The fourth drive unit, the fifth drive unit, the sixth drive unit and the seventh drive unit are arranged sequentially in the form of a rectangle, are provided below four corners of the second platform, and are in screwed connection with the second platform; and the fifth drive unit is provided below the second drive unit, and the sixth drive unit is provided below the third drive unit. It is assumed that a z-axis is perpendicular to the movable platform top, an x-axis is from the fifth drive unit to the sixth drive unit, and a y-axis is from the fifth drive unit to the fourth drive unit.

In order to optimize the above technical solutions, the measures taken further include:

the second platform is provided with a first sensor assembly horizontally facing the third edge, and a second sensor assembly and a third sensor assembly horizontally facing the fourth edge;

a fourth sensor assembly vertically facing the second platform is provided between the fourth drive unit and the fifth drive unit; a fifth sensor assembly vertically facing the second platform is provided between the fifth drive unit and the sixth drive unit; and a sixth sensor assembly vertically facing the second platform is provided between the sixth drive unit and the seventh drive unit.

The sixth guide units, namely the first guide unit, the second guide unit, the third guide unit, the fourth guide unit, the fifth guide unit and the sixth guide unit have the same structure, comprising a fifth rigid portion connected to the first platform, and a half-frame-shaped frame body enclosing the outside of the fifth rigid portion, first flexible sheets connected between ends of the frame body and the fifth rigid portion, first protrusions provided on the frame body, second flexible sheets connected to the first protrusions and perpendicular to the first flexible sheets, second protrusions provided on the second platform and connected to the second flexible sheets at the other end thereof. The second protrusions are located between the first protrusions and the first platform.

The first drive unit, the second drive unit and the third drive unit have the same structure, comprising a first bridge-type amplification mechanism and a first piezoelectric actuator provided inside the first bridge-type amplification mechanism. The first piezoelectric actuator is parallel to the first flexible sheet. The first bridge-type amplification mechanism comprises a first rigid portion and a third rigid portion respectively provided at two ends of the first piezoelectric actuator, and a second rigid portion and a fourth rigid portion provided on two sides of the first piezoelectric actuator and forming gaps therewith. A third flexible sheet is connected between adjacent ones of the first rigid portion, the second rigid portion, the third rigid portion and the fourth rigid portion. The distance between one end of the third flexible sheet and a middle section of the first piezoelectric actuator is smaller than the distance between the other end of the third flexible sheet and an end of the first piezoelectric actuator.

The second rigid portion is screwed to the frame body, and the fourth rigid portion is screwed to the fifth rigid portion.

The fourth drive unit, the fifth drive unit, the sixth drive unit and the seventh drive unit have the same structure, comprising a second piezoelectric actuator, and a second bridge-type amplification mechanism and a third bridge-type amplification mechanism which are respectively in the shape of a ring. The second bridge-type amplification mechanism is parallel to the base. Two ends of the second piezoelectric actuator are provided in an abutting manner inside the second bridge-type amplification mechanism. The third bridge-type amplification mechanism is sleeved on the periphery of the second bridge-type amplification mechanism, and the plane where the third bridge-type amplification mechanism is located is perpendicular to the extending and retracting direction of the second piezoelectric actuator. The third bridge-type amplification mechanism is screwed to the second platform and the base.

The second bridge-type amplification mechanism comprises a sixth rigid portion and a seventh rigid portion provided in an abutting manner at two ends of the second piezoelectric actuator, an eighth rigid portion and a ninth rigid portion respectively provided on two sides of the second piezoelectric actuator and forming gaps therewith, and fifth flexible sheets for connecting the sixth rigid portion, the eighth rigid portion, the seventh rigid portion and the ninth rigid portion two by two. The third bridge-type amplification mechanism comprises a tenth rigid portion screwed to the eighth rigid portion, an eleventh rigid portion screwed to the ninth rigid portion, a twelfth rigid portion screwed to the second platform, a thirteenth rigid portion screwed to the base, and seventh flexible sheets for connecting the tenth rigid portion, the twelfth rigid portion, the eleventh rigid portion and the thirteenth rigid portion two by two. The second bridge-type amplification mechanism and the third bridge-type amplification mechanism are respectively diamond-shaped. The first bridge-type amplification mechanism can amplify the input displacement of the first piezoelectric actuator by more than 10 times, thereby greatly enlarging the displacement stroke of the first platform. The second bridge-type amplification mechanism and the third bridge-type amplification mechanism can amplify the input displacement of the second piezoelectric actuator by more than 10 times, thereby greatly enlarging the displacement stroke of the second platform2.

In the upper platform, a pair of third flexible sheet and fourth flexible sheet arranged in parallel in the first bridge-type amplification mechanism constitute a single parallel four-link mechanism with the second rigid portion and the first rigid portion, and a pair of third flexible sheet and fourth flexible sheet arranged in parallel on the other side of the second rigid portion also constitute a single parallel four-link mechanism with the second rigid portion and the third rigid portion, such that the two single parallel four-link mechanisms constitute a dual parallel four-link mechanism. Similarly, the third flexible sheets and the fourth flexible sheets located on two sides of the fourth rigid portion also constitute a dual parallel four-link mechanism with the fourth rigid portion, the first rigid portion and the third rigid portion. When the first piezoelectric actuator receives a voltage, the above dual parallel four-link mechanisms enable the drive units to output a strict translational displacement through the fourth rigid portion without generating a parasitic displacement.

The first sensor assembly, the second sensor assembly and the third sensor assembly have the same structure, comprising a pedestal screwed to the frame body, and a sensor probe screwed to the pedestal, wherein the sensor probe is directly opposite the fifth rigid portion.

The fourth sensor assembly, the fifth sensor assembly and the sixth sensor assembly have the same structure, comprising a pedestal screwed to the base, and a sensor probe screwed to the pedestal, wherein the sensor probe is directly opposite the second platform.

The pedestal comprises a first plate fixed to the base or the frame body, and a second plate parallel to the first plate and fixedly connected to the sensor probe. A pair of flexible folded beams are connected between the first plate and the second plate. The center of the first plate is provided with a first threaded hole, and a first screw with an end abutting against the second plate is screwed into the first threaded hole.

The second platform is provided with a first accommodation groove for accommodating the first platform and forming a gap therewith, and a second accommodation groove located at an edge of the first accommodation groove and used for accommodating the first guide unit, the second guide unit, the third guide unit, the fourth guide unit, the fifth guide unit and the sixth guide unit. The frame bodies and the second flexible sheets are provided inside the second accommodation groove and form gaps therewith.

The first platform is higher than upper surfaces of the second platform, the first drive unit, the second drive unit and the third drive unit. The first bridge-type amplification mechanism further comprises fourth flexible sheets for sequentially connecting the first rigid portion, the second rigid portion, the third rigid portion and the fourth rigid portion. The fourth flexible sheets are provided between the third flexible sheets and the first piezoelectric actuator and form gaps therewith.

The second bridge-type amplification mechanism further comprises sixth flexible sheets connected sequentially for connecting adjacent ones of the sixth rigid portion, the eighth rigid portion, the seventh rigid portion and the ninth rigid portion. The sixth flexible sheets are provided between the second piezoelectric actuator and the fifth flexible sheets and form gaps therewith. In the lower platform, a pair of fifth flexible sheet and sixth flexible sheet arranged in parallel in the second bridge-type amplification mechanism constitute a single parallel four-link mechanism with the eighth rigid portion and the sixth rigid portion, and a pair of fifth flexible sheet and sixth flexible sheet arranged in parallel on the other side of the eighth rigid portion also constitute a single parallel four-link mechanism with the eighth rigid portion and the seventh rigid portion, such that the two single parallel four-link mechanisms constitute a dual parallel four-link mechanism. Similarly, the fifth flexible sheets and the sixth flexible sheets located on two sides of the ninth rigid portion also constitute a dual parallel four-link mechanism with the ninth rigid portion, the sixth rigid portion and the seventh rigid portion. When the second piezoelectric actuator receives a voltage, the above dual parallel four-link mechanisms enable the eighth rigid portion and the ninth rigid portion to output a strict translational displacement along an axis of third threaded holes in the two rigid portions, such that the twelfth rigid portion also outputs a strict translational displacement along the z-axis without generating a parasitic displacement.

In the lower platform, the seventh flexible sheets in the third bridge-type amplification mechanism enable the twelfth rigid portion to rotate both about the x-axis and the y-axis, and enables the twelfth rigid portion to rotate about one axis without generating a coupled angular rotation about the other axis, and therefore enables the second platform to rotate about one axis without generating a coupled angular rotation about the other axis.

An enclosure is provided on the periphery of the base, and a tubular body penetrating the base is provided at the center thereof. The enclosure is provided below the second platform and forms a gap therewith. The tubular body is provided below the first platform and forms a gap therewith. The movable platform top is provided with a first hollow hole adapted to the contour of the tubular body. The first platform is provided with a second hollow hole adapted to the contour of the tubular body.

The first platform, the second platform, the first guide unit, the second guide unit, the third guide unit, the fourth guide unit, the fifth guide unit and the sixth guide unit are of an integrally formed structure, that is, the first platform, the second platform and the flexible guide members are integrally formed by means of cutting. The base, the first bridge-type amplification mechanism, the second bridge-type amplification mechanism, the third bridge-type amplification mechanism, and the pedestal are respectively of an integrally formed structure.

Compared with the prior art, the six-degree-of-freedom large-stroke uncoupling large hollow series-parallel piezoelectric micro-motion platform of the present invention comprises a base and a movable platform top which is provided above the base and forms a gap therewith; wherein a second platform is provided between the movable platform top and the base and forms gaps therewith; a first platform, which is screwed to the movable platform top, is provided at the center of the second platform and forms a gap therewith; the first platform comprises a first edge, a second edge, a third edge and a fourth edge which are arranged sequentially perpendicular to each other in a counterclockwise direction of the first platform; a first guide unit capable of elastic deformation is connected between the second platform and the first edge; a second guide unit and a third guide unit capable of elastic deformation are respectively connected between the second platform and the second edge; a fourth guide unit capable of elastic deformation is connected between the second platform and the third edge; a fifth guide unit and a sixth guide unit capable of elastic deformation are respectively connected between the second platform and the fourth edge; the first guide unit is internally provided with a first drive unit capable of extending and retracting in the direction of the first platform, the second guide unit is internally provided with a second drive unit capable of extending and retracting in the direction of the first platform, and the third guide unit is internally provided with a third drive unit capable of extending and retracting in the direction of the first platform; and the base is provided with a fourth drive unit, a fifth drive unit, a sixth drive unit and a seventh drive unit which perpendicularly extend and retract to act on the second platform. The fourth drive unit, the fifth drive unit, the sixth drive unit and the seventh drive unit are arranged sequentially in the form of a rectangle, are provided below four corners of the second platform, and are in screwed connection with the second platform; and the fifth drive unit is provided below the second drive unit, and the sixth drive unit is provided below the third drive unit. Compared with the existing six-degree-of-freedom piezoelectric micro-motion platforms, the present invention has the advantages as follows.

1) The entire micro-motion platform is composed of two layers connected in series, namely upper and lower layers, and each layer is of a parallel structure, wherein for the upper platform, a movable platform, i.e. the first platform is driven by the first drive unit, the second drive unit and the third drive unit to realize the translations of the movable platform top in the x- and y-directions and the rotation thereof about the z-axis; and for the lower platform, a further movable platform, i.e. the second platform is driven by the fourth drive unit, the fifth drive unit, the sixth drive unit and the seventh drive unit to realize the translation of the movable platform top in the z-direction and the rotations thereof about the x- and y-axes. The output direction of the drive units is perpendicular to the axis of the piezoelectric actuator. In this way, the axis of the piezoelectric actuator in the upper platform is parallel to the edges of the first and second platforms, the drive units can be closely combined with the first platform and the second platform, the axis of the piezoelectric actuator in the lower platform is also parallel to the second platform and a bottom face of the base, and the movable platform top is close to the bottom face of the base, so that the micro-motion platform has a simple and compact overall structure and a large working platform top.

3) The bridge-type amplification mechanisms in the drive units can amplify the input displacement of the piezoelectric actuators by more than 10 times, thereby greatly enlarging the displacement stroke of the movable platform top.

3) In the upper platform, a pair of second flexible sheets and a frame body in each guide unit constitute a single parallel four-link mechanism with the second platform, and the two oppositely-arranged guide units constitute a dual parallel four-link mechanism through their respective pairs of second flexible sheets and the frame bodies together with the second platform. When a voltage is applied to the first drive unit and the same voltage is applied to the second drive unit and third drive unit at the same time, the movable platform body and the movable platform top output strict translational displacements in the x and y directions without generating a parasitic displacement.

4) In the upper platform, a pair of third flexible sheet and fourth flexible sheet arranged in parallel in the first bridge-type amplification mechanism constitute a single parallel four-link mechanism with the second rigid portion and the first rigid portion, and a pair of third flexible sheet and fourth flexible sheet arranged in parallel on the other side of the second rigid portion also constitute a single parallel four-link mechanism with the second rigid portion and the third rigid portion, such that the two single parallel four-link mechanisms constitute a dual parallel four-link mechanism. Similarly, the third flexible sheets and the fourth flexible sheets located on two sides of the fourth rigid portion also constitute a dual parallel four-link mechanism with the fourth rigid portion, the first rigid portion and the third rigid portion. When the first piezoelectric actuator receives a voltage, the above dual parallel four-link mechanisms enable the drive units to output a strict translational displacement through the fourth rigid portion without generating a parasitic displacement.

5) In the lower platform, a pair of fifth flexible sheet and sixth flexible sheet arranged in parallel in the second bridge-type amplification mechanism constitute a single parallel four-link mechanism with the eighth rigid portion and the sixth rigid portion, and a pair of fifth flexible sheet and sixth flexible sheet arranged in parallel on the other side of the eighth rigid portion also constitute a single parallel four-link mechanism with the eighth rigid portion and the seventh rigid portion, such that the two single parallel four-link mechanisms constitute a dual parallel four-link mechanism. Similarly, the fifth flexible sheets and the sixth flexible sheets located on two sides of the ninth rigid portion also constitute a dual parallel four-link mechanism with the ninth rigid portion, the sixth rigid portion and the seventh rigid portion. When the second piezoelectric actuator receives a voltage, the above dual parallel four-link mechanisms enable the eighth rigid portion and the ninth rigid portion to output a strict translational displacement along an axis of third threaded holes in the two rigid portions, such that the twelfth rigid portion also outputs a strict translational displacement in the z-direction without generating a parasitic displacement.

6) In the lower platform, the seventh flexible sheets in the third bridge-type amplification mechanism enable the twelfth rigid portion to rotate both about the x-axis and the y-axis, and enables the twelfth rigid portion to rotate about one axis without generating a coupled angular rotation about the other axis, and therefore enables the second platform to rotate about one axis without generating a coupled angular rotation about the other axis.

7) The upper platform has no coupled movement when implementing the translations of the movable platform top in the x- and y-directions and the rotation thereof about the z-axis, and the lower platform also has no coupled movement when implementing the translation of the movable platform top in the z direction and the rotations thereof about the x- and y-axes. so that the kinematics solution of and motion control over the movable platform top become simple and easy.

8) In the upper platform, the guide units have relatively large rectangular through holes, leaving enough space for the integration of displacement sensors (such as capacitive displacement sensors) into the upper platform; whereas in the lower platform, the drive units have a compact overall structure and are enabled to be arranged at the four corners of the base, leaving enough space for the integration of displacement sensors (such as capacitive displacement sensors) into the base, so that the displacement sensors (such as capacitive displacement sensors) can be easily integrated.

9) In the upper platform, a pair of second flexible sheets of each guide unit are located outside the first platform, the drive unit and the displacement sensor are located in the guide unit; whereas in the lower platform, the drive unit is close to the four corners of the base, and the displacement sensor is close to the enclosure of the base, so that the movable platform top and the tubular body have a large hollow, which can not only significantly reduce the mass of the movable platform body and the movable platform top, but can also greatly improve the inherent frequency of the platform. In addition, when the platform is used as an adjustment mechanism of an optical system, such a large hollow hole can be used as a large light transmission aperture.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings.

FIGS. 1 to 17are schematic structural diagrams of the present invention, in which the reference numerals are as follows: base1, first guide unit101, second guide unit102, third guide unit103, fourth guide unit104, fifth guide unit105, sixth guide unit106, enclosure11, tubular body12, second platform2, first accommodation groove21, second accommodation groove22, first drive unit31, second drive unit32, third drive unit33, fourth drive unit34, fifth drive unit35, sixth drive unit36, seventh drive unit37, first sensor assembly41, second sensor assembly42, third sensor assembly43, fourth sensor assembly44, fifth sensor assembly45, sixth sensor assembly46, first platform5, first edge51, second edge52, third edge53, fourth edge54, second hollow hole55, movable platform top6, first hollow hole602, second bridge-type amplification mechanism61, sixth rigid portion611, seventh rigid portion612, eighth rigid portion613, ninth rigid portion614, fifth flexible sheet615, sixth flexible sheet616, third bridge-type amplification mechanism62, second piezoelectric actuator63, tenth rigid portion621, eleventh rigid portion622, twelfth rigid portion623, thirteenth rigid portion624, seventh flexible sheet625, fifth rigid portion71, first flexible sheet72, frame body73, first protrusion74, second flexible sheet75, second protrusion76, first bridge-type amplification mechanism8, first rigid portion81, second rigid portion82, third rigid portion83, fourth rigid portion84, first piezoelectric actuator85, third flexible sheet86, fourth flexible sheet87, first plate91, first threaded hole911, first screw912, flexible folded beam92, second plate93, sensor probe94, and pedestal95.

FIGS. 1 to 17are schematic structural diagrams of the present invention. As shown inFIG. 2, a six-degree-of-freedom large-stroke uncoupling large hollow series-parallel piezoelectric micro-motion platform comprises a base1and a movable platform top6which is provided above the base1and forms a gap therewith. A second platform2is provided between the movable platform top6and the base1and forms gaps therewith. A first platform5, which is screwed to the movable platform top6, is provided at the center of the second platform2and forms a gap therewith. The first platform5comprises a first edge51, a second edge52, a third edge53and a fourth edge54which are arranged sequentially perpendicular to each other in a counterclockwise direction of the first platform. A first guide unit101capable of elastic deformation is connected between the second platform2and the first edge41. A second guide unit102and a third guide unit103capable of elastic deformation are respectively connected between the second platform2and the second edge42. A fourth guide unit104capable of elastic deformation is connected between the second platform2and the third edge41. A fifth guide unit105and a sixth guide unit106capable of elastic deformation are respectively connected between the second platform2and the fourth edge41. The first guide unit101is internally provided with a first drive unit31capable of extending and retracting in the direction of the first platform5, the second guide unit102is internally provided with a second drive unit32capable of extending and retracting in the direction of the first platform5, and the third guide unit103is internally provided with a third drive unit33capable of extending and retracting in the direction of the first platform5. The base1is provided with a fourth drive unit34, a fifth drive unit35, a sixth drive unit36and a seventh drive unit37which perpendicularly extend and retract to act on the second platform2. The fourth drive unit34, the fifth drive unit35, the sixth drive unit36and the seventh drive unit37are arranged sequentially in the form of a rectangle, are provided below four corners of the second platform2, and are in screwed connection with the second platform2. The fifth drive unit35is provided below the second drive unit32, and the sixth drive unit36is provided below the third drive unit33. In an non-working state, the first drive unit31, the second drive unit32and the third drive unit33are connected to the edges of the first platform5. The first drive unit31, the second drive unit32, the third drive unit33, the fourth drive unit34, the fifth drive unit35, the sixth drive unit36and the seventh drive unit37are any linear motors, and are preferably linear motors having piezoelectric actuators.

It is assumed that a z-axis is perpendicular to the movable platform top6, and an x-axis is from the fifth drive unit35to the sixth drive unit36. A y-axis is from the fifth drive unit35to the fourth drive unit34. By coordinating and controlling the movements of the first drive unit31, the second drive unit32and the third drive unit33, the movable platform top6can generate two translations and one rotation. Moreover, by coordinating and controlling the movements of the fourth drive unit34, the fifth drive unit35, the sixth drive unit36and the seventh drive unit37, the movable platform top6can generate the other three movements, i.e., two rotations and one translation.

In an embodiment, as shown inFIGS. 2, 3, 4, 5 and 6, the fourth guide unit104is internally provided with a first sensor assembly41facing the third edge53, the fifth guide unit105is internally provided with a second sensor assembly42facing the fourth edge54, and the sixth guide unit106is internally provided with a third sensor assembly43facing the fourth edge54. The first sensor assembly41can detect the displacement amount of the third edge53, and the second sensor assembly42and the third sensor assembly43can detect the displacement amounts of the fourth edge54, comprising the rotation angle of the first platform5about the z-axis.

As shown inFIG. 2, a fourth sensor assembly44vertically facing the second platform2is provided between the fourth drive unit34and the fifth drive unit35. A fifth sensor assembly45vertically facing the second platform2is provided between the fifth drive unit35and the sixth drive unit36. A sixth sensor assembly46vertically facing the second platform2is provided between the sixth drive unit36and the seventh drive unit37. The fourth sensor assembly44, the fifth sensor assembly45and the sixth sensor assembly46can detect the displacement amounts of the second platform2, comprising the displacement amount lifted along the z-axis, the displacement amount rotated along the x-axis, and the displacement amount rotated along the y-axis.

In the embodiment, as shown inFIGS. 2, 3, 4, 5, 6, 7 and 11, the sixth guide units, namely the first guide unit101, the second guide unit102, the third guide unit103, the fourth guide unit104, the fifth guide unit105and the sixth guide unit106have the same structure, comprising a fifth rigid portion71connected to the first platform5, and a half-frame-shaped frame body73enclosing the outside of the fifth rigid portion71, first flexible sheets72connected between ends of the frame body73and the fifth rigid portion71, first protrusions74provided on the frame body73, second flexible sheets75connected to the first protrusions74and perpendicular to the first flexible sheets72, second protrusions76provided on the second platform2and connected to the second flexible sheets75at the other end thereof. The second protrusions76are located between the first protrusions74and the first platform5.

As shown inFIGS. 7 and 11, the first drive unit31, the second drive unit32and the third drive unit33have the same structure, comprising a first bridge-type amplification mechanism8and a first piezoelectric actuator85provided inside the first bridge-type amplification mechanism8. The first piezoelectric actuator85is parallel to the first flexible sheet72. The first bridge-type amplification mechanism8comprises a first rigid portion81and a third rigid portion83respectively provided at two ends of the first piezoelectric actuator85, and a second rigid portion82and a fourth rigid portion84provided on two sides of the first piezoelectric actuator85and forming gaps therewith. A third flexible sheet86is connected between adjacent ones of the first rigid portion81, the second rigid portion82, the third rigid portion83and the fourth rigid portion84. The distance between one end of the third flexible sheet86and a middle section of the first piezoelectric actuator85is smaller than the distance between the other end of the third flexible sheet86and an end of the first piezoelectric actuator85. When the first piezoelectric actuator85is energized and extended, the first piezoelectric actuator85pushes the first rigid portion81and the third rigid portion83away from each other, and the third flexible sheet86is straightened by the first rigid portion81and the third rigid portion83, the second rigid portion82and the fourth rigid portion84are then separated from each other, and finally the fourth rigid portion84pushes a movable platform body4to move via the fifth rigid portion71. The bridge-type amplification mechanism composed of the third flexible sheets86, the first rigid portion81, the second rigid portion82, the third rigid portion83and the fourth rigid portion84can amplify the input displacement of the first piezoelectric actuator85by more than 10 times, thereby greatly enlarging the displacement stroke of the first platform5and the movable platform top6. The second rigid portion82is screwed to the frame body73, and the fourth rigid portion84is screwed to the fifth rigid portion71.

The fourth drive unit34, the fifth drive unit35, the sixth drive unit36and the seventh drive unit37have the same structure, comprising a second piezoelectric actuator63, and a second bridge-type amplification mechanism61and a third bridge-type amplification mechanism62which are respectively in the shape of a ring. The second bridge-type amplification mechanism61is parallel to the base1. Two ends of the second piezoelectric actuator63are provided in an abutting manner inside the second bridge-type amplification mechanism61. The third bridge-type amplification mechanism62is sleeved on the periphery of the second bridge-type amplification mechanism61, and the plane where the third bridge-type amplification mechanism62is located is perpendicular to the extending and retracting direction of the second piezoelectric actuator63. The third bridge-type amplification mechanism62is screwed to the second platform2and the base1. The first bridge-type amplification mechanism8can amplify the input displacement of the first piezoelectric actuator85by more than 10 times, thereby greatly enlarging the displacement stroke of the first platform5. The second bridge-type amplification mechanism61and the third bridge-type amplification mechanism62can amplify the input displacement of the second piezoelectric actuator63by more than 10 times, thereby greatly enlarging the displacement stroke of the second platform2.

After the first piezoelectric actuator85is energized, the first piezoelectric actuator85is extended and stretches the first rigid portion81and the third rigid portion83, and the third flexible sheet86that was originally inclined to the first piezoelectric actuator85will be straightened, the second rigid portion82and the fourth rigid portion84are then pulled apart from each other, and finally the fourth rigid portion84pushes the first platform5via the fifth rigid portion71. The guide units provide support for the first bridge-type amplification mechanism8. All the first protrusions74, the second protrusions76and the second flexible sheets75in the same guide unit constitute a parallel four-link mechanism, and two oppositely-arranged guide units constitute a dual parallel four-link mechanism. The dual parallel four-link mechanism can prevent the platform from generating coupled angular rotation during translation. Since when outputting displacement in a certain direction, the first platform5is guided by the guide unit in that direction, the first platform5will produce a strict linear displacement when translating in that direction, and will not generate coupled displacements in other directions, so that the movement accuracy of the movable platform top6is greatly improved.

As shown inFIGS. 15, 16 and 17, the fourth drive unit34, the fifth drive unit35, the sixth drive unit36and the seventh drive unit37have the same structure, comprising a second piezoelectric actuator63, and a second bridge-type amplification mechanism61and a third bridge-type amplification mechanism62which are respectively in the shape of a ring. The second bridge-type amplification mechanism61is parallel to the base1. Two ends of the second piezoelectric actuator63are provided in an abutting manner inside the second bridge-type amplification mechanism61. The third bridge-type amplification mechanism62is sleeved on the periphery of the second bridge-type amplification mechanism61, and the plane where the third bridge-type amplification mechanism62is located is perpendicular to the extending and retracting direction of the second piezoelectric actuator63. The third bridge-type amplification mechanism62is screwed to the second platform2and the base1. When the second piezoelectric actuator63is energized, the second piezoelectric actuator63stretches the second bridge-type amplification mechanism61, the second bridge-type amplification mechanism61is narrowed and brings the second piezoelectric actuator63to be narrowed transversely, and the height of the second piezoelectric actuator63is increased, and finally the corresponding portion of the second platform2is lifted.

In an embodiment, as shown inFIGS. 15, 16 and 17, the second bridge-type amplification mechanism61comprises a sixth rigid portion611and a seventh rigid portion612provided in an abutting manner at two ends of the second piezoelectric actuator63, an eighth rigid portion613and a ninth rigid portion614respectively provided on two sides of the second piezoelectric actuator63and forming gaps therewith, and fifth flexible sheets615for connecting the sixth rigid portion611, the eighth rigid portion613, the seventh rigid portion612and the ninth rigid portion614two by two.

The third bridge-type amplification mechanism62comprises a tenth rigid portion621screwed to the eighth rigid portion613, an eleventh rigid portion622screwed to the ninth rigid portion614, a twelfth rigid portion623screwed to the second platform2, a thirteenth rigid portion624screwed to the base1, and seventh flexible sheets625for connecting the tenth rigid portion621, the twelfth rigid portion623, the eleventh rigid portion622and the thirteenth rigid portion624two by two. The second bridge-type amplification mechanism61and the third bridge-type amplification mechanism62are respectively diamond-shaped. When the second piezoelectric actuator63is energized, the second piezoelectric actuator63stretches the sixth rigid portion611and the seventh rigid portion612, the fifth flexible sheets615are straightened from the inclined state by the sixth rigid portion611and the seventh rigid portion612, the eighth rigid portion613and the ninth rigid portion614move close to each other, the tenth rigid portion621and the eleventh rigid portion622are also synchronously pulled close to each other by the eighth rigid portion613and the ninth rigid portion614, the seventh flexible sheets625are straightened from the inclined state and stretches the twelfth rigid portion623and the thirteenth rigid portion624, and finally the corresponding portion of the second platform2is lifted.

In the lower platform, a pair of fifth flexible sheet615and sixth flexible sheet616arranged in parallel in the second bridge-type amplification mechanism61constitute a single parallel four-link mechanism with the eighth rigid portion613and the sixth rigid portion611, and a pair of fifth flexible sheet615and sixth flexible sheet616arranged in parallel on the other side of the eighth rigid portion613also constitute a single parallel four-link mechanism with the eighth rigid portion613and the seventh rigid portion612, such that the two single parallel four-link mechanisms constitute a dual parallel four-link mechanism. Similarly, the fifth flexible sheets615and the sixth flexible sheets616located on two sides of the ninth rigid portion614also constitute a dual parallel four-link mechanism with the ninth rigid portion614, the sixth rigid portion611and the seventh rigid portion612. When the second piezoelectric actuator63receives a voltage, the above dual parallel four-link mechanisms enable the eighth rigid portion613and the ninth rigid portion614to output a strict translational displacement along an axis of third threaded holes631in the two rigid portions, such that the twelfth rigid portion also outputs a strict translational displacement along the z-axis without generating a parasitic displacement.

In the lower platform, the seventh flexible sheets625in the third bridge-type amplification mechanism62enable the twelfth rigid portion623to rotate both about the x-axis and the y-axis, and enables the twelfth rigid portion623to rotate about one axis without generating a coupled angular rotation about the other axis, and therefore enables the second platform2to rotate about one axis without generating a coupled angular rotation about the other axis.

In an embodiment, as shown inFIGS. 2, 3, 4, 5, 6, and 12, the first sensor assembly41, the second sensor assembly42and the third sensor assembly43have the same structure, comprising a pedestal95screwed to the frame body73, and a sensor probe94screwed to the pedestal95, wherein the sensor probe94is directly opposite the fifth rigid portion71. The fourth sensor assembly44, the fifth sensor assembly45and the sixth sensor assembly46have the same structure, comprising a pedestal95screwed to the base1, and a sensor probe94screwed to the pedestal95, wherein the sensor probe94is directly opposite the second platform2. In the embodiment, as shown inFIGS. 12 and 14, the pedestal95comprises a first plate91fixed to the base1or the frame body73, and a second plate93parallel to the first plate91and fixedly connected to the sensor probe94. A pair of flexible folded beams92are connected between the first plate91and the second plate93. The center of the first plate91is provided with a first threaded hole911, and a first screw912with an end abutting against the second plate93is screwed into the first threaded hole911. Tightening the first screw912can increase the distance between the second plate93and the first plate91, thereby reducing the distance between the sensor probe94and the fifth rigid portion71. When the first screw912is loosened, the flexible folded beams92can reduce the distance between the second plate93and the first plate91, thereby increasing the distance between the sensor probe94and the fifth rigid portion71. By screwing the first screw912, the distance between the second plate93and the first plate91can be adjusted by means of the elastic deformation of the flexible folded beams92, thereby adjusting the distance between the sensor probe94and the fifth rigid portion71.

In an embodiment, as shown inFIGS. 9 and 10, the second platform2is provided with a first accommodation groove21for accommodating the first platform5and forming a gap therewith, and a second accommodation groove22located at an edge of the first accommodation groove21and used for accommodating the first guide unit101, the second guide unit102, the third guide unit103, the fourth guide unit104, the fifth guide unit105and the sixth guide unit106. The frame bodies73and the second flexible sheets75are provided inside the second accommodation groove22and form gaps therewith. The first accommodation groove21accommodates the first drive unit31, the second drive unit32, the third drive unit33, the first sensor assembly41, the second sensor assembly42and the third sensor assembly43, and the second accommodation groove22accommodates the first platform5, so that the overall thickness of the product of the present invention is thinner than that of the first platform5superimposed on the second platform2.

In an embodiment, as shown inFIG. 7, the first platform5is higher than upper surfaces of the second platform2, the first drive unit31, the second drive unit32and the third drive unit33. The first bridge-type amplification mechanism8further comprises fourth flexible sheets87for sequentially connecting the first rigid portion81, the second rigid portion82, the third rigid portion83and the fourth rigid portion84. The fourth flexible sheets87are provided between the third flexible sheets86and the first piezoelectric actuator85and form gaps therewith. In the upper platform, a pair of third flexible sheet86and fourth flexible sheet87arranged in parallel in the first bridge-type amplification mechanism101constitute a single parallel four-link mechanism with the second rigid portion82and the first rigid portion81, and a pair of third flexible sheet86and fourth flexible sheet87arranged in parallel on the other side of the second rigid portion82also constitute a single parallel four-link mechanism with the second rigid portion82and the third rigid portion83, such that the two single parallel four-link mechanisms constitute a dual parallel four-link mechanism. Similarly, the third flexible sheets86and the fourth flexible sheets87located on two sides of the fourth rigid portion84also constitute a dual parallel four-link mechanism with the fourth rigid portion84, the first rigid portion84and the third rigid portion83. When the first piezoelectric actuator85receives a voltage, the above dual parallel four-link mechanisms enable the drive units to output a strict translational displacement through the fourth rigid portion without generating a parasitic displacement.

As shown inFIGS. 15, 16 and 17, the second bridge-type amplification mechanism61is provided with sixth flexible sheets616for connecting adjacent ones of the sixth rigid portion611, the eighth rigid portion613, the seventh rigid portion612and the ninth rigid portion614. The sixth flexible sheets616are provided between the second piezoelectric actuator63and the fifth flexible sheets615and form gaps therewith. The sixth flexible sheets616can enhance the restoring ability of the second bridge-type amplification mechanism61.

In an embodiment, as shown inFIG. 2, an enclosure11is provided on the periphery of the base1, and a tubular body12penetrating the base1is provided at the center thereof. The enclosure11is provided below the second platform2and forms a gap therewith. The tubular body12is provided below the first platform5and forms a gap therewith. The movable platform top6is provided with a first hollow hole602adapted to the contour of the tubular body12. The first platform5is provided with a second hollow hole55adapted to the contour of the tubular body12. The enclosure11and the tubular body12can prevent foreign matter from entering the device. The first hollow hole602and the second hollow hole55can not only reduce the mass of the first platform5and the movable platform top1, but can also serve as a light transmission aperture when the platform is used as an adjustment mechanism of an optical system.

In an embodiment, as shown inFIG. 7, the first bridge-type amplification mechanism (8) is of an integrally formed structure. The first rigid portion81, the second rigid portion82, the third rigid portion83, the fourth rigid portion84, the third flexible sheets86and the fourth flexible sheets87are of an integrally formed structure.

As shown inFIGS. 5, 6 and 9, the first platform5, the second platform2, the first guide unit101, the second guide unit102, the third guide unit103, the fourth guide unit104, the fifth guide unit105and the sixth guide unit106are of an integrally formed structure, that is, the first platform5, the second platform2and the guide units are integrally formed by means of cutting.

The base1, the first bridge-type amplification mechanism8, the second bridge-type amplification mechanism61, the third bridge-type amplification mechanism62, and the pedestal95are respectively of an integrally formed structure.

The present invention enables the movable platform to realize six-degree-of-freedom movements, and the specific working principle is as follows:

it is assumed that the z-axis is perpendicular to the movable platform top6, the x-axis is from the fifth drive unit35to the sixth drive unit36, and the y-axis is from the fifth drive unit35to the fourth drive unit34, the working principle of the present invention is:

if only the fourth drive unit34, the fifth drive unit35, the sixth drive unit36, and the seventh drive unit37are applied with the same voltage at the same time and output the same vertical displacement amount, the movable platform top6is lifted along the z-axis, so that the movement of the movable platform top6along the z-axis is achieved without generating coupled displacements in the other directions;

if only the first drive unit31is applied with a voltage, the first drive unit31pushes the first platform5and finally the movable platform top6is moved along the x-axis, so that the movement of the movable platform top6along the x-axis is achieved without generating coupled displacements in the other directions;

if only the second drive unit32and the third drive unit33are applied with the same voltage at the same time and output the same horizontal displacement amount, the first platform5moves along the y-axis together with the movable platform top6, so that the movement of the movable platform top6along the y-axis is achieved without generating coupled displacements in the other directions;

if only the sixth drive unit36and the seventh drive unit37are applied with the same voltage at the same time and output the same vertical displacement amount, the movable platform top6rotates about the y-axis, so that the rotation of the movable platform top6about the y-axis is achieved without generating coupled displacements in the other directions;

if only the fourth drive unit34and the seventh drive unit37are applied with the same voltage at the same time and output the same perpendicular displacement amount, the movable platform top6rotates about the x-axis, so that the rotation of the movable platform top6about the x-axis is achieved without generating coupled displacements in the other directions; and

if only the second drive unit32or the third drive unit33is applied with a voltage, the first platform5rotates about the z-axis together with the movable platform top6, so that the rotation of the movable platform top6about the z-axis is achieved without generating coupled displacements in the other directions.

The preferred embodiments of the present invention have been explained, and various changes or modifications made by those skilled in the art will not depart from the scope of the present invention.