Zero-rigidity large-stroke two-degree-of-freedom parallel rotating platform based on compliant mechanism

Abstract

The invention discloses a zero-rigidity large-stroke two-degree-of-freedom parallel rotating platform based on a compliant mechanism, and relates to the field of precision positioning. The problems that an existing two-degree-of-freedom rotating platform is small in stroke, poor in dynamic performance and high in driving force requirement are solved. A center hooke joint is installed on a base, two sets of guide mechanisms are installed on the base in the X-axis direction and the Y-axis direction with the center hooke joint as the center respectively, a deflection platform is installed on the center hooke joint, and two extending parts of the deflection platform are connected with one set of guide mechanisms through one needle-shaped hinge respectively. The guide mechanism comprises a motor base, a zero-force spring connector, a voice coil motor and a plurality of zero-force springs, the motor base is installed on the base, the voice coil motor is installed on the motor base, the zero-force spring connector is installed on the voice coil motor, and the lower portion of the needle-shaped hinge is connected with the voice coil motor. The method is used for two-degree-of-freedom precise positioning.

Description

Technical Field

[0001] The invention relates to the field of precision positioning, and in particular to a zero-rigidity, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism. Background Art

[0002] Applications such as space laser communications, optical mirror pointing, laser scanning, and micro-nano manipulation require optical platforms to have high precision in two degrees of freedom, large deflection angles, and high dynamic performance. Currently, the precision of the rotating platform based on roller bearings is difficult to improve due to unfavorable factors such as friction, wear, and clearance, and its bloated structure limits its dynamic performance.

[0003] The two-degree-of-freedom rotating platform based on magnetic suspension has the problems of high heat generation, small load capacity and difficult control, which limits its application scenarios. The two-degree-of-freedom rotating platform based on compliant mechanism has the advantages of no friction, no gap, no need for lubrication and maintenance, and is easy to design parallel configuration to improve its dynamic performance, thus attracting much attention in the field of multi-degree-of-freedom precision rotating platform.

[0004] However, the current two-degree-of-freedom rotating platforms based on compliant mechanisms generally use compliant mechanisms as guide mechanisms, and their stiffness is usually large to ensure the feasibility of the processing technology and improve the lateral stiffness, which leads to a large requirement for the actuator driving force under a large stroke. Therefore, to improve the stroke and dynamic performance of the two-degree-of-freedom rotating platform based on the compliant mechanism, it is often accompanied by an increase in the power of the actuator, and its volume also increases at the same time, which makes it difficult to integrate and miniaturize the rotating platform.

[0005] In summary, the existing two-degree-of-freedom rotation platform has the problems of small stroke, poor dynamic performance and high driving force requirement. Summary of the invention

[0006] The purpose of the present invention is to solve the problems of small stroke, poor dynamic performance and high driving force requirement of the existing two-degree-of-freedom rotating platform, and further provide a zero-rigidity large-stroke two-degree-of-freedom parallel rotating platform based on a compliant mechanism.

[0007] The technical solution of the present invention is:

[0008] A zero-rigidity, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism comprises a deflection platform, a central Hooke's hinge, a needle hinge, a base and two sets of guide mechanisms; the central Hooke's hinge is installed on the base, the two sets of guide mechanisms are respectively installed on the base in the X-axis direction and the Y-axis direction with the central Hooke's hinge as the center, the deflection platform is installed on the central Hooke's hinge, and the two extensions of the deflection platform are respectively connected to a set of guide mechanisms through a needle hinge; the guide mechanism comprises a motor base, a zero-force spring connector, a voice coil motor and a plurality of zero-force springs, the motor base is installed on the base, the voice coil motor is installed on the motor base, the zero-force spring connector is installed on the voice coil motor, and the zero-force spring connector is connected to the plurality of zero-force springs installed on the motor base, and the lower part of the needle hinge is connected to the voice coil motor.

[0009] Furthermore, the deflection platform includes a platform mounting plate and two extension parts. The platform mounting plate is a square plate, and a wire mounting hole is opened in the center of the platform mounting plate. Multiple mounting holes are opened around the wire mounting hole. The two extension parts are installed on two adjacent sides to form a right angle.

[0010] Preferably, the central Hooke's hinge is a hollow sheet hinge structure.

[0011] Furthermore, the zero-force spring connector includes an upper plate and four spring mounting plates. The upper plate is a circular plate body. The four spring mounting plates are installed on the outer edge of the upper plate in a circular array and extend downward. A spring mounting hole is provided on each spring mounting plate, and a hinge through hole is provided in the center of the upper plate.

[0012] Preferably, the zero-force spring is a rectangular metal sheet that is bent to form an annular elastic body.

[0013] Furthermore, mounting holes are respectively provided in the middle and at two ends of the rectangular metal sheet.

[0014] Furthermore, the voice coil motor includes a voice coil motor stator and a voice coil motor mover, the voice coil motor stator is mounted on the motor base, the voice coil motor mover is mounted in the voice coil motor stator, and the voice coil motor mover moves up and down along the voice coil motor stator after power is supplied.

[0015] Furthermore, the lower part of the needle hinge is fixedly connected to the voice coil motor mover.

[0016] Furthermore, the motor base includes a rectangular base body and four angle irons, and the four angle irons are vertically installed on the four corners of the rectangular base body respectively.

[0017] Preferably, each angle iron is provided with a spring mounting hole.

[0018] Compared with the prior art, the present invention has the following effects:

[0019] 1. The present invention can save effort and thus reduce the requirement for driving power: since most of the work done by the motor is used to rotate the platform, the present invention does not need to convert the kinetic energy of the voice coil motor into the strain energy of the zero-force spring 5. Therefore, in a static state, the motor output does not increase significantly with the increase of displacement, thereby reducing the requirement for driving power;

[0020] 2. The present invention has high dynamic performance: the present invention is a second-order dynamic system dominated by inertia and damping (the damping is mainly provided by the electromagnetic damping of the voice coil motor, and the inertia is provided by the rotating output platform 1, the zero-force spring connector 4 and the voice coil motor), the stiffness is extremely low, and there is no system resonance caused by noise or high-frequency components of the control signal, so the gain can be increased by increasing the motor output, thereby improving the dynamic performance;

[0021] 3. The present invention can realize platform movement with a large stroke: Since most of the two-degree-of-freedom rotating platform guide mechanisms based on compliant mechanisms have a large stiffness, the larger the stroke, the higher the motor output requirement, which results in a small stroke of the rotating platform using a small-sized motor; while the present invention uses a zero-force spring as a guide mechanism, which can achieve a larger stroke, and the stroke size is theoretically limited only by the zero-force spring stroke size, the allowable stress of the pin hinge and the center Hooke hinge. The zero-force spring used has a large stroke.

[0022] 4. The present invention has the advantages of small size and high compactness: compared with the traditional zero-force spring that adopts the buckling effect and the superposition of positive and negative stiffness, the zero-force spring adopted by the present invention has higher compactness in the same small volume, thereby making the overall rotating platform more compact under the same stroke. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of the present invention, Figure 2 yes Figure 1 A top view of Figure 3 yes Figure 2 Section view along AA, Figure 4 This is a schematic diagram of the zero-force spring manufacturing process. Figure 5 This is a schematic diagram of the structure of the central Hooke's hinge 2. Figure 6 This is a schematic diagram of the structure of a pin hinge. Figure 7 This is a schematic diagram of the motor base structure. Figure 8 It is a schematic diagram of the mechanism of the zero-force spring connector. DETAILED DESCRIPTION

[0024] Specific implementation method 1: Combination Figures 1 to 8The present embodiment is described, and the present embodiment includes a deflection platform 1, a central Hooke's hinge 2, a needle hinge 3, a base 9 and two sets of guide mechanisms; the central Hooke's hinge 2 is mounted on the base 9, and the two sets of guide mechanisms are respectively mounted on the base 9 in the X-axis direction and the Y-axis direction with the central Hooke's hinge 2 as the center, the deflection platform 1 is mounted on the central Hooke's hinge 2, and the two extensions of the deflection platform 1 are respectively connected to a set of guide mechanisms through a needle hinge 3; the guide mechanism includes a motor base 8, a zero-force spring connector 4, a voice coil motor and a plurality of zero-force springs 5, the motor base 8 is mounted on the base 9, the voice coil motor is mounted on the motor base 8, the zero-force spring connector 4 is mounted on the voice coil motor, and the zero-force spring connector 4 is connected to the plurality of zero-force springs 5 ​​mounted on the motor base 8, and the lower part of the needle hinge 3 is connected to the voice coil motor.

[0025] The present invention is a parallel configuration, providing two rotational degrees of freedom, Rx and Ry, and can achieve ±5 degree displacement output in both degrees of freedom. The present invention uses a pure compliance mechanism (guide mechanism) as a transmission mechanism, so it theoretically has infinite transmission accuracy, and its accuracy only depends on the accuracy of the voice coil motor used.

[0026] Since the present embodiment adopts the zero-force spring 5 as a guide and the needle hinge 3 and the center Hooke's hinge 2 have very small stiffness, the static driving force required by the rotating platform does not increase significantly with the increase of displacement. Therefore, within the full stroke, the voice coil motor is only required to overcome gravity, thereby achieving the purpose of saving effort.

[0027] In dynamic conditions, since the dynamics of the present invention are dominated by inertia and motor damping, the elastic effect is very weak, so the adverse effects of resonance can be effectively avoided. This means that as long as the motor driving force is sufficient, the present invention can have sufficiently high dynamic performance without considering the resonance problem caused by noise or the high-frequency part of the driving signal.

[0028] Specific implementation method 2: Combination Figures 1 to 3 To illustrate this embodiment, the deflection platform 1 of this embodiment includes a platform mounting plate 1-1 and two extension parts 1-2. The platform mounting plate 1-1 is a square plate, and a wire mounting hole is opened at the center of the platform mounting plate 1-1, and multiple mounting holes are opened around the wire mounting hole. The two extension parts 1-2 are installed on two adjacent sides and form a right angle.

[0029] In this way, the platform mounting plate 1-1 is mainly used to install precision positioning equipment in various environments, and provides a degree of freedom of movement direction through the two extension parts 1-2, playing a connecting role. Other components and connection relationships are the same as those in the first specific embodiment.

[0030] Specific implementation method three: Combination Figure 1 , Figure 3 and Figure 4 The present embodiment is described. The central Hooke's hinge 2 of the present embodiment is a sheet-like hinge structure with a hollow structure.

[0031] In this way, the other end of the deflection platform 1 is connected to the base through the central Hooke's hinge 2. The central Hooke's hinge 2 provides the rotation center of Rx and Ry, and adopts a sheet hinge as the deformation sensitive part, thereby improving the deformation ability while reducing its stress concentration phenomenon. The central Hooke's hinge 2 adopts a hollow structure, which on the one hand provides a light hole for the optical load, and on the other hand can ensure that the tension applied by the voice coil motor on the needle hinge 3 is always between the two sheet hinges of the corresponding degree of freedom on the central Hooke's hinge 2, thereby reducing the interference with another degree of freedom. Other components and connection relationships are the same as those of the first or second specific implementation.

[0032] Specific implementation method four: Combination Figure 8 To illustrate this embodiment, the zero-force spring connector 4 of this embodiment includes an upper plate 4-1 and four spring mounting plates 4-2. The upper plate 4-1 is a circular plate. The four spring mounting plates 4-2 are mounted on the outer edge of the upper plate 4-1 in a circular array and extend downward. A spring mounting hole 4-3 is provided on each spring mounting plate 4-2, and a hinge through hole 4-4 is provided in the center of the upper plate 4-1.

[0033] With such arrangement, in actual use of this embodiment, the zero-force spring connector 4 is arranged to be plugged in relative to the motor base 8. This arrangement is mainly used to simultaneously connect to both sides of the zero-force spring 5. After the two sides of the zero-force spring 5 are connected to the zero-force spring connector 4 and the motor base 8, the motor base 8 is stationary. When the zero-force spring connector 4 is moved up and down under the action of the voice coil motor, the spring mounting plate 4-2 of the zero-force spring connector 4 drives one side of the zero-force spring 5 to move up and down, causing the zero-force spring 5 to produce elastic deformation. The other components and connection relationships are the same as any one of the specific embodiments one to three.

[0034] The thickness of the spring mounting plate 4 - 2 in this embodiment is the same as the width of the zero-force spring 5 , which is convenient for ensuring the connection strength and service life.

[0035] Specific implementation method five: Combination Figure 4 To describe this embodiment, the zero-force spring 5 of this embodiment is a rectangular metal sheet that is bent to form an annular elastic body.

[0036] In this arrangement, necessary fixing holes are firstly processed on a rectangular metal (or other non-metallic material) sheet, which is then bent and clamped between the motor base 8 and the zero-force spring connector 4, and fixed by bolts. Since the length and shape of the bent portion of the zero-force spring remain unchanged during the movement of the voice coil motor stator 6, its strain energy remains unchanged, thereby achieving the purpose of zero force. In this way, the output of the voice coil motor only needs to be used to drive the deflection platform 1 to move without having to be converted into a large amount of elastic potential energy like a traditional compliant mechanism (only a very small amount of kinetic energy is converted into strain energy and stored in the needle hinge 3 and the center Hooke's hinge 2 in the present invention), thereby achieving the purpose of saving effort. The other structures and components are the same as any one of the specific embodiments one to four.

[0037] Specific implementation method six: Combination Figure 4 To describe this embodiment, mounting holes are respectively provided in the middle and at two ends of the rectangular metal sheet.

[0038] Such arrangement facilitates the connection between the zero-force spring 5, the zero-force spring connector 4 and the motor base 8. Other components and connection relationships are the same as any one of the specific implementation modes 1 to 3.

[0039] Specific implementation method seven: Combination Figure 1 The present embodiment is described. The voice coil motor of the present embodiment includes a voice coil motor stator 7 and a voice coil motor mover 6. The voice coil motor stator 7 is mounted on a motor base 8. The voice coil motor mover 6 is mounted inside the voice coil motor stator 7. The voice coil motor mover 6 moves up and down along the voice coil motor stator 7 after power is supplied.

[0040] In this configuration, the present invention uses a voice coil motor as an actuator, the stator 7 of the voice coil motor is fixed on the motor base, and the mover 6 of the voice coil motor is fixedly connected to the zero-force spring connector 3. One end of the zero-force spring 5 is fixedly connected to the motor base 8, and the other end is fixedly connected to the zero-force spring connector 3, thereby providing guidance for the movement of the voice coil motor.

[0041] The present invention uses eight zero-force springs (the number of zero-force springs used should not be limited to the number in this case) in a symmetrical combination to provide guidance for a voice coil motor, thereby improving its lateral anti-interference ability. Other components and connection relationships are the same as any one of the specific embodiments 1 to 6.

[0042] Specific implementation method eight: Combination Figure 3 The present embodiment is described. In the present embodiment, the lower portion of the pin hinge 3 is fixedly connected to the voice coil motor mover 6 .

[0043] Such arrangement facilitates the lifting and lowering of the extension part 1-2 driven by the voice coil motor mover 6. Other components and connection relationships are the same as any one of the specific implementation modes 1 to 7.

[0044] Specific implementation method nine: Combination Figure 7 To explain this embodiment, the motor base 8 of this embodiment includes a rectangular base body 8-1 and four angle irons 8-2. The four angle irons 8-2 are vertically installed on the four corners of the rectangular base body 8-1 respectively.

[0045] In this way, the angle iron 8-2 can simultaneously connect the middle parts of the zero-force springs 5 ​​on both sides, which can save space while ensuring the connection strength. The other components and connection relationships are the same as any one of the specific implementation modes 1 to 8.

[0046] Specific implementation method ten: Combination Figure 7 To describe this embodiment, in this embodiment, each angle iron 8-2 is provided with a spring mounting hole.

[0047] Such arrangement facilitates detachable connection with the middle part of the zero-force spring 5. Other components and connection relationships are the same as any one of the specific embodiments 1 to 8.

[0048] The needle hinge 3 is used to transmit motion and force between the zero-force spring connector 3 and the deflection platform 1. Because the needle hinge 3 has a large aspect ratio, it can provide two rotational degrees of freedom, and has low bending stiffness and high axial stiffness, which reduces the component of the reaction force of the deflection platform 1 on the plane, thereby reducing the requirement for the zero-force spring 5 to resist lateral interference.

[0049] The invention discloses a zero-rigidity, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism, which has the following features:

[0050] 1. 2DOF large rotation stroke: Through the large-stroke flexible hinge design, the two rotational degrees of freedom Rx and Ry reach ±5deg stroke

[0051] 2. New belt-shaped constant force mechanism: The belt-shaped constant force mechanism is used for guidance to reduce the processing requirements of the voice coil motor. Compared with the traditional constant force mechanism, which requires a starting force to make the reed enter the buckling state before entering the constant force stage, the belt-shaped constant force mechanism designed in this paper is pure constant force, does not require a starting stage, and has a large constant force stroke and small fluctuations.

[0052] 3. High dynamics: The system stiffness is small under the constant force mechanism, the DC gain is large, and the resonance is small. The gain can be increased to cross the resonance point and increase the bandwidth. (The system gain is small with high stiffness, and a larger force is required to achieve a large stroke; the resonance amplitude is large due to high stiffness, and the maximum operating frequency needs to be lower than the resonance frequency to prevent noise interference).

[0053] When the voice coil motor mover 6 coil is energized, an Ampere force is generated under the magnetic field of the voice coil motor stator 7, thereby pushing the voice coil motor mover 6 and the zero-force spring connector 4 connected thereto to move upward. Since the zero-force spring connector 4 is connected to the motor base 8 through the zero-force spring 5, the zero-force spring 5 provides a guide for its vertical movement. Since the needle hinge 3 has two rotational degrees of freedom and is connected to the deflection platform 1 together with the center Hooke's hinge 2, when the zero-force spring connector 4 pushes the needle hinge 3 to move upward, it will be forced to rotate around the center Hooke's hinge 2 on the corresponding rotational degrees of freedom, thereby converting the translation of the voice coil motor into rotation. Since the two degrees of freedom Rx and Ry are orthogonal and arranged in parallel, the movements of the two degrees of freedom can be decoupled and do not interfere with each other.

[0054] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A zero-stiffness, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism, characterized by: It comprises a deflection platform (1), a central Hooke's hinge (2), a needle hinge (3), a base (9) and two sets of guide mechanisms; The central Hooke's hinge (2) is mounted on the base (9), two sets of guide mechanisms are respectively mounted on the base (9) in the X-axis direction and the Y-axis direction with the central Hooke's hinge (2) as the center, the deflection platform (1) is mounted on the central Hooke's hinge (2), and two extensions of the deflection platform (1) are respectively connected to a set of guide mechanisms via a needle hinge (3); The guide mechanism comprises a motor base (8), a zero-force spring connector (4), a voice coil motor and a plurality of zero-force springs (5); the motor base (8) is mounted on a base (9); the voice coil motor is mounted on the motor base (8); the zero-force spring connector (4) is mounted on the voice coil motor; the zero-force spring connector (4) is connected to the plurality of zero-force springs (5) mounted on the motor base (8); and the lower part of the needle hinge (3) is connected to the voice coil motor.

2. A zero-stiffness, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism according to claim 1, characterized in that: The deflection platform (1) comprises a platform mounting plate (1-1) and two extension parts (1-2); the platform mounting plate (1-1) is a square plate; a wire mounting hole is provided at the center of the platform mounting plate (1-1); a plurality of mounting holes are provided around the wire mounting hole; and the two extension parts (1-2) are mounted on two adjacent sides to form a right angle.

3. The zero-stiffness, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism according to claim 1, characterized in that: The central Hooke's hinge (2) is a sheet-shaped hinge structure with a hollow structure.

4. A zero-stiffness, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism according to claim 3, characterized in that: The zero-force spring connector (4) comprises an upper plate (4-1) and four spring mounting plates (4-2); the upper plate (4-1) is a circular plate; the four spring mounting plates (4-2) are mounted on the outer edge of the upper plate (4-1) in a circular array and extend downward; each spring mounting plate (4-2) is provided with a spring mounting hole (4-3); and a hinge through hole (4-4) is provided at the center of the upper plate (4-1).

5. A zero-stiffness, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism according to claim 4, characterized in that: The zero-force spring (5) is a rectangular metal sheet that is bent to form an annular elastic body.

6. A zero-stiffness, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism according to claim 5, characterized in that: The middle part and two ends of the rectangular metal sheet are respectively provided with mounting holes.

7. A zero-stiffness, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism according to claim 6, characterized in that: The voice coil motor comprises a voice coil motor stator (7) and a voice coil motor mover (6). The voice coil motor stator (7) is mounted on a motor base (8), the voice coil motor mover (6) is mounted in the voice coil motor stator (7), and the voice coil motor mover (6) moves up and down along the voice coil motor stator (7) after power is supplied.

8. The zero-rigidity, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism according to claim 7, characterized in that: The lower part of the needle hinge (3) is fixedly connected to the voice coil motor mover (6).

9. A zero-rigidity, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism according to claim 1 or 8, characterized in that: The motor base (8) comprises a rectangular base body (8-1) and four angle irons (8-2), wherein the four angle irons (8-2) are respectively vertically mounted on the four corners of the rectangular base body (8-1).

10. A zero-rigidity, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism according to claim 9, characterized in that: Each angle iron (8-2) is provided with a spring mounting hole.

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