A zero-stiffness large-stroke two-degree-of-freedom parallel rotation platform based on a compliant mechanism

Abstract

The application discloses a zero-rigidity large-stroke two-degree-of-freedom parallel rotation platform based on a compliant mechanism and relates to the field of precision positioning. The application solves the problems of small stroke, poor dynamic performance and high driving force requirement of the existing two-degree-of-freedom rotation platform. The center hooke joint is installed on the base, two groups of guide mechanisms are installed on the base in the X-axis direction and the Y-axis direction respectively with the center hooke joint as the center, the deflection platform is installed on the center hooke joint, and the two extension parts of the deflection platform are connected with a group of guide mechanisms through a needle-shaped hinge respectively. The guide mechanism comprises a motor base, a zero-force spring connecting body, 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 connecting body is installed on the voice coil motor, and the lower part of the needle-shaped hinge is connected with the voice coil motor. The application is used for two-degree-of-freedom precision positioning.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of precision positioning, and in particular to a zero-stiffness large-stroke two-degree-of-freedom parallel rotation platform based on a compliant mechanism. BACKGROUND

[0002] Space laser communication, optical mirror pointing, laser scanning, micro-nano operation and other application scenarios require the optical platform to have two degrees of freedom, high precision, large deflection angle and high dynamic performance. The current rotation platform based on roller bearings has the problems of friction, wear, gap and other unfavorable factors, which makes it difficult to improve the precision, and its structure is relatively bulky, which limits its dynamic performance.

[0003] The two-degree-of-freedom rotation platform based on magnetic suspension has the problems of large heat generation, small load capacity and difficult control, which limits its application scenarios. The two-degree-of-freedom rotation platform based on a compliant mechanism has the advantages of no friction, no gap, no lubrication and maintenance, and is easy to design a parallel configuration to improve its dynamic performance, so it is concerned in the field of multi-degree-of-freedom precision rotation platform.

[0004] However, the current two-degree-of-freedom rotation platform based on a compliant mechanism generally uses a compliant mechanism as a guide mechanism, and its stiffness is usually large to ensure the feasibility of the machining process and improve the lateral stiffness, which leads to a large requirement for the driving force of the actuator at a large stroke. Therefore, to improve the stroke and dynamic performance of the two-degree-of-freedom rotation platform based on a compliant mechanism, the power of the actuator is usually increased, and the volume is also increased, which causes difficulties in the integration and miniaturization of the rotation 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

[0006] The purpose of the present application is to solve the problems of small stroke, poor dynamic performance and high driving force requirement of the existing two-degree-of-freedom rotation platform. Further, a zero-stiffness large-stroke two-degree-of-freedom parallel rotation platform based on a compliant mechanism is provided.

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

[0008] A kind of zero stiffness large stroke two-degree-of-freedom parallel rotation platform based on compliant mechanism includes deflection platform, center hooke joint, needle-shaped hinge, base and two groups of guide mechanism;Center hooke joint is installed on base, and two groups of guide mechanism are installed on base with center hooke joint as center and in X-axis direction and Y-axis direction respectively, deflection platform is installed on center hooke joint, and two extensions of deflection platform are connected with a group of guide mechanism by a needle-shaped hinge respectively;Guide mechanism includes motor base, zero force spring connecting body, voice coil motor and multiple zero force springs, motor base is installed on base, voice coil motor is installed on motor base, zero force spring connecting body is installed on voice coil motor, and multiple zero force springs are connected with zero force spring connecting body installed on motor base, and the lower part of needle-shaped hinge is connected with voice coil motor.

[0009] Further, deflection platform includes platform mounting plate and two extensions, platform mounting plate is square plate, and the center of platform mounting plate is provided with wire mounting hole, multiple mounting holes are provided around wire mounting hole, and two extensions are installed on two adjacent edges and form right angle.

[0010] Preferably, center hooke joint is sheet hinge structure with hollow structure.

[0011] Further, zero force spring connecting body includes upper plate and four spring mounting plates, upper plate is circular plate body, four spring mounting plates are installed on the outer edge of upper plate in the form of annular array and extend downward, and spring mounting hole is provided on each spring mounting plate, and hinge through hole is provided in the center of upper plate.

[0012] Preferably, zero force spring is rectangular metal sheet after bending to form annular elastic body.

[0013] Further, the middle part and two end parts of rectangular metal sheet are provided with mounting holes respectively.

[0014] Further, voice coil motor includes voice coil motor stator and voice coil motor rotor, voice coil motor stator is installed on motor base, voice coil motor rotor is installed in voice coil motor stator, and voice coil motor rotor moves up and down along voice coil motor stator after being electrified.

[0015] Further, the lower part of needle-shaped hinge is fixedly connected with voice coil motor rotor.

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

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

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

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

[0020] 2. The present invention has high dynamic performance: The present invention is a second-order dynamic system dominated by inertia and damping (damping is mainly provided by the electromagnetic damping of the voice coil motor, and inertia is provided by the rotating output platform 1, the zero-force spring connector 4 and the voice coil motor). It has extremely low stiffness and does not have system resonance caused by noise or high-frequency components of the control signal. Therefore, the gain can be increased by increasing the motor output, thereby improving the dynamic performance;

[0021] 3. The present invention enables long-range platform motion: Most existing two-degree-of-freedom rotating platform guide mechanisms based on compliant mechanisms have relatively high stiffness. Consequently, larger travel requires higher motor output, resulting in a smaller platform travel using a smaller motor. However, the present invention utilizes a zero-force spring as a guide mechanism, enabling a longer travel. Theoretically, the travel is limited only by the zero-force spring travel and the allowable stresses of the pin hinge and center Hooke's hinge. The zero-force spring employed provides a relatively long travel.

[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 Cross-sectional 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 structural diagram of the motor base. 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 embodiment is described as follows. The embodiment includes a deflection platform 1, a center hooke joint 2, a needle-shaped hinge 3, a base 9, and two sets of guide mechanisms. The center hooke joint 2 is installed on the base 9, the two sets of guide mechanisms are installed on the base 9 in the X-axis direction and the Y-axis direction respectively and centered on the center hooke joint 2, the deflection platform 1 is installed on the center hooke joint 2, and two extension parts of the deflection platform 1 are connected with one set of guide mechanisms respectively through one needle-shaped hinge 3. The guide mechanism includes a motor base 8, a zero-force spring connecting body 4, a voice coil motor, and a plurality of zero-force springs 5. The motor base 8 is installed on the base 9, the voice coil motor is installed on the motor base 8, the zero-force spring connecting body 4 is installed on the voice coil motor, and the zero-force spring connecting body 4 is connected with the plurality of zero-force springs 5 installed on the motor base 8. The lower part of the needle-shaped hinge 3 is connected with the voice coil motor.

[0025] The parallel configuration of the embodiment provides two rotation degrees of freedom of Rx and Ry, and can realize a displacement output of ±5 degrees in both degrees of freedom. The pure compliant mechanism (guide mechanism) is used as a transmission mechanism, so that the transmission precision is theoretically infinitely high, and the precision depends only on the precision of the voice coil motor.

[0026] Since the zero-force spring 5 is used as a guide in the embodiment, and the stiffness of the needle-shaped hinge 3 and the center hooke joint 2 is very small, the static driving force required by the rotation platform does not increase significantly with the increase of displacement, so that the voice coil motor mainly overcomes the gravity in the whole stroke, and the purpose of saving labor is achieved.

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

[0028] Specific implementation method two: combination Figures 1 to 3 The embodiment is described as follows. The deflection platform 1 of the embodiment includes a platform mounting plate 1-1 and two extension parts 1-2. The platform mounting plate 1-1 is a square plate, a lead wire mounting hole is formed in the center of the platform mounting plate 1-1, a plurality of mounting holes are formed around the lead wire mounting hole, and 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 for installing precise positioning equipment in various environments, and the two extension parts 1-2 provide the movement direction of the degree of freedom, and play a connecting role. The other components and connection relationship are the same as those of the first embodiment.

[0030] Specific implementation method three: combination Figure 1 , Figure 3 andFigure 4 The center hooke joint 2 in this embodiment is a sheet-shaped hooke joint structure with a hollow structure.

[0031] In this way, the other end of the deflection platform 1 is connected to the base through the center hooke joint 2. The center hooke joint 2 provides the Rx and Ry rotation centers, and uses a sheet-shaped hooke joint as the deformation sensitive part, thereby improving the deformation ability while reducing the stress concentration phenomenon. The center hooke joint 2 has a hollow structure, which on the one hand provides a light transmission hole for the optical load, and on the other hand can ensure that the tension applied by the voice coil motor on the needle-shaped hooke joint 3 is always between the two sheet-shaped hooke joints corresponding to the two degrees of freedom of the center hooke joint 2, thereby reducing the interference on the other degree of freedom. The other components and connection relationships are the same as those in embodiment one or two.

[0032] Embodiment four: combination Figure 8 In this embodiment, the zero-force spring connecting body 4 includes an upper plate 4-1 and four spring mounting plates 4-2. The upper plate 4-1 is a circular plate body, and the four spring mounting plates 4-2 are installed in a ring array on the outer edge of the upper plate 4-1 and extend downward, and each spring mounting plate 4-2 is provided with a spring mounting hole 4-3, and the center of the upper plate 4-1 is provided with a hooke joint passing hole 4-4.

[0033] In this way, in actual use, the zero-force spring connecting body 4 is relatively inserted between the motor base 8, and this arrangement is mainly used to connect the two sides of the zero-force spring 5 at the same time. When the two sides of the zero-force spring 5 are connected to the zero-force spring connecting body 4 and the motor base 8, the motor base 8 is stationary, and when the zero-force spring connecting body 4 moves up and down under the action of the voice coil motor, the spring mounting plate 4-2 of the zero-force spring connecting body 4 drives one side of the zero-force spring 5 to move up and down, so that the zero-force spring 5 is elastically deformed. The other components and connection relationships are the same as those in any one of 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] Embodiment five: combination Figure 4 In this embodiment, the zero-force spring 5 is a rectangular metal sheet bent to form a ring-shaped elastic body.

[0036] In this way, first, the necessary fixing holes are processed on the rectangular metal (or other non-metallic material) sheet, then it is bent and clamped between the motor base 8 and the zero-force spring connecting body 4, and fixed by bolts. Since the length and shape of the bent part 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 push the deflection platform 1 to move without a large amount of elastic potential energy conversion as in the traditional compliant mechanism (only a small amount of kinetic energy is converted into strain energy stored in the needle hinge 3 and the center hinge 2 in the present application), thereby achieving the purpose of saving force. The other structures and compositions are the same as any one of embodiments 1 to 4.

[0037] Embodiment six: combination Figure 4 To illustrate this embodiment, the middle part and the two end parts of the rectangular metal sheet are respectively provided with mounting holes.

[0038] In this way, it is convenient to realize the connection of the zero-force spring 5 with the zero-force spring connecting body 4 and the motor base 8. The other compositions and connection relationships are the same as any one of embodiments 1 to 3.

[0039] Embodiment seven: combination Figure 1 To illustrate this embodiment, the voice coil motor of this embodiment includes a voice coil motor stator 7 and a voice coil motor mover 6, the voice coil motor stator 7 is installed on the motor base 8, the voice coil motor mover 6 is installed 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 being energized.

[0040] In this way, the present application uses a voice coil motor as an actuator, the voice coil motor stator 7 is fixed on the motor base, and the voice coil motor mover 6 and the zero-force spring connecting body 4 are fixedly connected. 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 connecting body 4, thereby providing guidance for the movement of the voice coil motor.

[0041] The present application uses eight zero-force springs (the number of zero-force springs used should not be limited to the number in this case) to provide guidance for a voice coil motor, thereby improving its side aspect anti-interference capability. The other compositions and connection relationships are the same as any one of embodiments 1 to 6.

[0042] Embodiment eight: combination Figure 3 To illustrate this embodiment, the lower part of the needle hinge 3 is fixedly connected with the voice coil motor mover 6.

[0043] In this way, it is convenient to realize the lifting of the extension part 1-2 under the driving of the voice coil motor mover 6. The other compositions and connection relationships are the same as any one of embodiments 1 to 7.

[0044] Specific implementation nine: combination Figure 7 In this embodiment, the motor base 8 includes a rectangular seat body 8-1 and four angle irons 8-2, which are respectively vertically installed on the four corners of the rectangular seat body 8-1.

[0045] In this way, the angle iron 8-2 can simultaneously realize the connection of the middle part of the zero-force spring 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 embodiments one to eight.

[0046] Specific implementation ten: combination Figure 7 In this embodiment, the spring mounting hole is formed in each angle iron 8-2.

[0047] In this way, it is convenient to detachably connect the middle part of the zero-force spring 5. The other components and connection relationships are the same as any one of the specific embodiments one to eight.

[0048] The needle-shaped hinge 3 is used to transmit motion and force between the zero-force spring connecting body 4 and the deflection platform 1. Because the needle-shaped hinge 3 has a large length-diameter ratio, it can provide two degrees of rotational 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 of the zero-force spring 5 for resisting lateral interference.

[0049] A zero-stiffness large-stroke two-degree-of-freedom parallel rotation platform based on a compliant mechanism has the following advantages:

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

[0051] 2. New belt constant force mechanism: the belt constant force mechanism is used for guidance, which reduces the processing demand of the voice coil motor. Compared with the traditional constant force mechanism, which needs to start the force to make the spring enter the buckling state, and then enter the constant force stage, the belt constant force mechanism designed in this paper is pure constant force, without the need for a starting stage, and has large constant force stroke and small fluctuation.

[0052] 3. High dynamic: the system stiffness is small under the constant force mechanism, the direct current gain is large, and the resonance is small, which can improve the gain to cross the resonance point to increase the bandwidth. (The large stiffness system has small gain, which needs larger force to realize large stroke; large stiffness causes large resonance amplitude, and the maximum working frequency needs to be lower than the resonance frequency to prevent noise interference.)

[0053] When the coil of the moving coil motor 6 is energized, an Ampere force is generated under the magnetic field of the stator 7 of the moving coil motor, thus pushing the moving coil motor 6 and the zero-force spring connecting body 4 connected thereto to move upward. Since the zero-force spring connecting body 4 is connected to the motor base 8 through the zero-force spring 5, the zero-force spring 5 provides a guide for the vertical direction movement of the zero-force spring connecting body 4. Since the needle hinge 3 has two rotational degrees of freedom and is connected to the deflection platform 1 together with the center hinge 2, when the zero-force spring connecting body 4 pushes the needle hinge 3 to move upward, it will force the needle hinge 3 to rotate around the center hinge 2 in the corresponding rotational degree of freedom, thus converting the translation of the moving coil motor into rotation. Since the two degrees of freedom Rx and Ry are arranged orthogonally and in parallel, the movements of the two degrees of freedom can be decoupled and run without interference.

[0054] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalent features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A zero-stiffness, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism, characterized by: It 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), 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 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), wherein 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, 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 portion of the needle hinge (3) is connected to the voice coil motor; The zero-force spring connector (4) 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. Each spring mounting plate (4-2) is provided with a spring mounting hole (4-3). The center of the upper plate (4-1) is provided with a hinge through hole (4-4). The zero-force spring (5) is a rectangular metal sheet bent to form an annular elastic body.

2. 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 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 hinge structure with a hollow structure.

4. The zero-stiffness, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism according to claim 3, characterized in that: The middle part and two end parts of the rectangular metal sheet are respectively provided with mounting holes.

5. The zero-stiffness, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism according to claim 4, characterized in that: The voice coil motor comprises a voice coil motor stator (7) and a voice coil motor mover (6), wherein 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 being energized.

6. The zero-stiffness, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism according to claim 5, characterized in that: The lower part of the needle-shaped hinge (3) is fixedly connected to the voice coil motor mover (6).

7. A zero-stiffness, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism according to claim 1 or 6, 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).

8. The zero-stiffness, large-stroke, two-degree-of-freedom parallel rotating platform based on a compliant mechanism according to claim 7, characterized in that: Each angle iron (8-2) is provided with a spring mounting hole.

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