Piezoelectric multi-degree-of-freedom actuator based on variable mode resonance driving

Abstract

This invention discloses a piezoelectric multi-degree-of-freedom actuator based on variable modal resonance drive, comprising a drive disk, a housing, a base, a drive mechanism, and a piezoelectric wafer. The housing is mounted on the base, the drive disk is located at the top of the housing, and the drive mechanism and piezoelectric wafer are integrated within the inner cavity of the housing. The piezoelectric wafer is connected to the drive mechanism, and the piezoelectric wafer drives the drive disk to perform vertical linear motion and oscillation at arbitrary angles and directions via the drive mechanism. The center of the bottom of the drive disk is hinged to a spherical hinge head via a hinge cap, allowing the drive disk to oscillate at arbitrary angles on the spherical hinge head. The straight rod at the bottom of the spherical hinge head is screwed to a connecting shaft below. The advantages include: precise control of the displacement amplification factor of the piezoelectric wafer, enabling changes in the displacement amplification ratio of the outer end of the piezoelectric wafer; adjustment of the vibration frequency of the piezoelectric wafer; and suitability for applications requiring angular positioning.

Description

Technical Field

[0001] This invention relates to a piezoelectric multi-degree-of-freedom actuator, and more particularly to a piezoelectric multi-degree-of-freedom actuator based on variable modal resonance drive. Background Technology

[0002] Currently, piezoelectric actuators utilize the inverse piezoelectric effect of piezoelectric materials. Applying an electric current to the piezoelectric material causes displacement, thereby achieving mechanical motion. Piezoelectric actuators are characterized by high sensitivity, fast response, simple structure, and no electromagnetic interference, making them an effective means of achieving precision motion and control. Fields such as precision instruments often require high-precision drive devices with multiple degrees of freedom. Traditional electromagnetic and hydraulic actuators are insufficient to meet these precision motion requirements.

[0003] Traditional piezoelectric actuators are mostly single-degree-of-freedom output devices, capable of linear motion in one direction or rotation around a fixed axis, making them unsuitable for complex working scenarios and thus limiting their application space. Existing multi-degree-of-freedom piezoelectric actuators typically require multiple actuators connected in series, resulting in large space requirements and complex structures. Furthermore, traditional actuators produce a fixed output value under the same power input, making them unsuitable for complex working environments. Therefore, this paper proposes a precision actuator with high space utilization, variable frequency output, and multi-degree-of-freedom output capabilities, enabling linear vibration output and oscillation output around a spherical pivot point. Summary of the Invention

[0004] This invention addresses the problem that traditional piezoelectric actuators are mostly single-degree-of-freedom outputs, which can only achieve linear motion output in one direction or rotational output around a fixed axis, making it difficult to cope with complex working scenarios. The invention provides a piezoelectric multi-degree-of-freedom actuator based on variable mode resonance drive.

[0005] The piezoelectric multi-degree-of-freedom actuator based on variable modal resonance driving provided by the present invention includes a drive disk, a housing, a base, a drive mechanism, and a piezoelectric wafer. The housing is assembled on the base, the drive disk is located at the top of the housing, the drive mechanism and the piezoelectric wafer are integrated in the inner cavity of the housing, the piezoelectric wafer is connected to the drive mechanism, and the piezoelectric wafer drives the drive disk to perform vertical linear motion and oscillation at arbitrary angles and directions through the drive mechanism.

[0006] The center part of the bottom of the drive disc is hinged to the spherical hinge head through a hinge head cap. The drive disc can swing at any angle on the spherical hinge head. The straight rod at the bottom of the spherical hinge head is screwed to the connecting shaft below. The straight rod at the bottom of the spherical hinge head is fitted with a hinge head seat, which is wrapped around the lower part of the spherical hinge head. The connecting shaft below the spherical hinge head is inserted into the center hole of the fixing seat at the center of the housing chassis. The connecting shaft can slide within the center hole of the fixing seat.

[0007] The bottom of the drive disc is provided with cross-shaped intersecting slides. The first slider on the drive mechanism is engaged with the slide and can slide along the slide.

[0008] The driving mechanism includes a first slider and a driving rod. The first slider is mounted on the top of the driving rod and is engaged with a slide rail at the bottom of the driving disk. The bottom of the driving rod is fixed to a piezoelectric crystal. The vibration of the piezoelectric crystal enables the driving rod to drive the first slider to slide along the slide rail at the bottom of the driving disk.

[0009] Four piezoelectric crystals are assembled, arranged in pairs in a cross shape. The cross-shaped piezoelectric crystals correspond to the cross-shaped slides at the bottom of the drive disk. The inner ends of the four piezoelectric crystals are fixed to the fixed base at the center of the housing chassis, and the outer ends of the four piezoelectric crystals are fixed to the drive rods on the drive mechanism. There are also four drive rods on the drive mechanism corresponding to the piezoelectric crystals.

[0010] Each piezoelectric crystal has an adjustment groove near the mounting base. A frequency conversion screw is installed in the adjustment groove. The natural frequency of the piezoelectric crystal can be adjusted by increasing or decreasing the number of frequency conversion screws and adjusting the position of the frequency conversion screws in the adjustment groove.

[0011] Each piezoelectric wafer is fitted with a second slider. A groove is provided on the base of the housing corresponding to the position of the second slider. The second slider can slide on the piezoelectric wafer and in the groove. A connecting rod is provided at the bottom of the second slider. The outer end of the connecting rod is fixed to the lifting platform. The lifting platform is fitted on the sliding shaft. The lifting platform can move up and down on the sliding shaft. The up and down movement of the lifting platform on the sliding shaft drives the second slider to slide on the piezoelectric wafer and in the groove through the connecting rod, thereby changing the position of the second slider on the piezoelectric wafer. The top of the sliding shaft is fixed to the bottom surface of the fixed seat in the middle of the housing base. An adjusting nut is installed on the sliding shaft at the bottom of the lifting platform. The set position of the lifting platform on the sliding shaft can be adjusted by adjusting the adjusting nut. A limit ring is installed on the sliding shaft below the adjusting nut for limiting the adjustment of the nut.

[0012] Working principle of the invention:

[0013] The piezoelectric multi-degree-of-freedom actuator based on variable modal resonance drive provided by this invention supplies power to the piezoelectric crystals. Adjusting the power supply's frequency, amplitude, and mode shape regulates the displacement of the piezoelectric crystals. This displacement is amplified by a second slider lever fulcrum mounted on the piezoelectric crystal and transmitted to the drive disk via a drive rod at the outer end of the crystal, thus controlling the actuator's displacement. By adjusting the power supply phase, the actuator's motion mode can be controlled, enabling both linear vertical vibration and oscillating motion around a spherical hinge at any angle, as well as simultaneous superposition of these two motions. Furthermore, the four piezoelectric crystals provide clamping force, maintaining high holding power even when power is off.

[0014] Each piezoelectric crystal has an adjustment groove to change its mass. The mass of the system can be increased or decreased by adding or removing a frequency converter screw, and the position of the frequency converter screw in the adjustment groove can be adjusted to change the natural frequency of the piezoelectric crystal.

[0015] The drive disc is connected to the spherical hinge head. The drive disc can not only achieve linear vibration, but also swing around the spherical hinge head at any angle, which can play a role in occasions where angle positioning is required (such as lens deflection angle control).

[0016] Four piezoelectric crystals are arranged symmetrically in pairs in a cross shape. Each piezoelectric crystal is independently powered. Due to the inverse piezoelectric effect, the piezoelectric crystals vibrate when an alternating current is applied. The vibration displacement of the piezoelectric crystals is transmitted to the drive plate at a certain amplification ratio, thereby realizing the driving function. The displacement amplification function is achieved by the second slider. Adjusting the position of the lifting platform can adjust the displacement amplification ratio. A frequency converter screw can also be added to change the natural frequency of the piezoelectric crystals.

[0017] The specific work process is as follows:

[0018] Linear displacement: When the amplitude, frequency, and phase of the alternating power supply for the four piezoelectric crystals are all the same, the displacement modes of the four piezoelectric crystals are the same. Therefore, the same displacement will be transmitted on the drive rod, causing the drive disk to move up and down in a linear motion. The magnitude of the displacement of the drive disk can be controlled by adjusting the power supply mode.

[0019] Swing displacement: The attitude of the drive disk in three-dimensional space is controlled by four sliding tracks. The phase difference of the electrical phase of two piezoelectric crystals with opposite control positions is T / 2 (T is the minimum positive period of the alternating power supply vibration). When all other parameters are the same, the displacement directions of the piezoelectric crystals are opposite. Therefore, the drive disk will tilt towards the drive rod direction with the displacement direction downward. Similarly, by adjusting the power supply of the other two opposite piezoelectric crystals at the same time, the tilt angle of the drive disk in another direction can be adjusted, thereby enabling the drive disk to swing around the spherical hinge head at any angle.

[0020] The beneficial effects of this invention are:

[0021] The piezoelectric multi-degree-of-freedom actuator based on variable modal resonance drive provided by this invention precisely controls the displacement amplification factor of the piezoelectric crystal through piezoelectric crystal drive and mechanical structure transmission. When it is necessary to adjust the actuator amplification factor during use, simply stop the power supply and adjust the height of the lifting platform to realize the sliding of the lever fulcrum on the sliding groove of the housing chassis, thereby changing the displacement amplification ratio of the outer end of the piezoelectric crystal. This adjustment device is located at the opening below the housing chassis and can be directly contacted, so it can be adjusted without disassembling the invention.

[0022] This invention can adjust the vibration frequency of piezoelectric crystals. Each piezoelectric crystal has an adjustment groove to change its mass. The mass of the system can be increased or decreased by adding or removing the frequency converter screw, or the stiffness of the piezoelectric crystal can be adjusted by changing the position of the frequency converter screw, thereby achieving the adjustment of the vibration frequency of the piezoelectric crystal.

[0023] The drive disc of the present invention is connected to the spherical hinge head, which can not only realize linear vibration, but also realize oscillation around the spherical hinge head at any angle, and can play a role in occasions where angle positioning is required (such as lens deflection angle control). Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the piezoelectric multi-degree-of-freedom actuator described in this invention.

[0025] Figure 2 This is a bottom view of the overall internal structure of the piezoelectric multi-degree-of-freedom actuator described in this invention.

[0026] Figure 3 This is a front view of the overall internal structure of the piezoelectric multi-degree-of-freedom actuator described in this invention.

[0027] Figure 4 This is a schematic diagram of the exploded structure of the piezoelectric multi-degree-of-freedom actuator described in this invention.

[0028] Figure 5 This is a schematic diagram of the piezoelectric wafer assembly structure described in this invention.

[0029] Figure 6 This is a schematic diagram of the bottom structure of the drive disk described in this invention.

[0030] Figure 7 This is a schematic diagram of the housing chassis structure described in this invention.

[0031] Figure 8 This is a schematic diagram of the piezoelectric wafer structure described in this invention.

[0032] Figure 9 This is a schematic diagram of the drive disk flipping control principle described in this invention.

[0033] Figure 10 This is a schematic diagram illustrating the principle of changing the amplification factor of the actuator described in this invention.

[0034] Figure 11 This is a schematic diagram illustrating the principle of changing the magnification factor by the fulcrum described in this invention.

[0035] The annotations in the image above are as follows:

[0036] 1. Drive plate 2. Housing 3. Base 4. Piezoelectric wafer 5. Hinge cap 6. Spherical hinge

[0037] 7. Connecting shaft; 8. Hinge head seat; 9. Fixed seat; 10. Slide rail; 11. First slider.

[0038] 12. Drive rod; 13. Adjustment groove; 14. Variable frequency screw; 15. Second slider; 16. Slide groove

[0039] 17. Connecting rod; 18. Lifting platform; 19. Sliding shaft; 20. Chassis; 21. Adjusting nut

[0040] 22. Limiting ring. Detailed Implementation

[0041] Please see Figures 1 to 11 As shown:

[0042] The piezoelectric multi-degree-of-freedom actuator based on variable modal resonance drive provided by the present invention includes a drive disk 1, a housing 2, a base 3, a drive mechanism, and a piezoelectric wafer 4. The housing 2 is mounted on the base 3, the drive disk 1 is located at the top of the housing 2, the drive mechanism and the piezoelectric wafer 4 are integrated in the inner cavity of the housing 2, the piezoelectric wafer 4 is connected to the drive mechanism, and the piezoelectric wafer 4 drives the drive disk 1 to perform vertical linear motion and oscillation at arbitrary angles and directions through the drive mechanism.

[0043] The center part of the bottom of the drive disk 1 is hinged to the ball joint 6 through the hinge cap 5. The drive disk 1 can swing at any angle on the ball joint 6. The straight rod at the bottom of the ball joint 6 is screwed to the connecting shaft 7 below. The straight rod at the bottom of the ball joint 6 is fitted with a hinge seat 8. The hinge seat 8 is wrapped around the lower part of the ball joint 6. The connecting shaft 7 below the ball joint 6 is inserted into the center hole of the fixing seat 9 at the center of the base 20 of the housing 2. The connecting shaft 7 can slide in the center hole of the fixing seat 9.

[0044] The bottom of the drive disk 1 is provided with cross-shaped intersecting slide rails 10. The first slider 11 on the drive mechanism is engaged with the slide rails 10 and can slide along the slide rails 10.

[0045] The driving mechanism includes a first slider 11 and a driving rod 12. The first slider 11 is mounted on the top of the driving rod 12 and is engaged with the slide rail 10 at the bottom of the driving disk 1. The bottom of the driving rod 12 is fixed to the piezoelectric crystal 4. The vibration of the piezoelectric crystal 4 enables the driving rod 12 to drive the first slider 11 to slide along the slide rail 10 at the bottom of the driving disk 1.

[0046] Four piezoelectric wafers 4 are assembled, and the four piezoelectric wafers 4 are arranged in pairs in a cross shape. The cross-shaped piezoelectric wafers 4 correspond to the cross-shaped slide rails 10 at the bottom of the drive disk 1. The inner ends of the four piezoelectric wafers 4 are all fixed to the fixed seat 9 at the center of the chassis 20 of the housing 2. The outer ends of the four piezoelectric wafers 4 are all fixed to the drive rods 12 on the drive mechanism. There are also four drive rods 12 on the drive mechanism corresponding to the piezoelectric wafers 4.

[0047] Each piezoelectric crystal 4 has an adjustment groove 13 near the fixing base 9. A frequency conversion screw 14 is installed in the adjustment groove 13. The natural frequency of the piezoelectric crystal 4 can be adjusted by increasing or decreasing the number of frequency conversion screws 14 and adjusting the position of the frequency conversion screws 14 in the adjustment groove 13.

[0048] Each piezoelectric wafer 4 is fitted with a second slider 15. A groove 16 is provided on the base 20 of the housing 2 at the position corresponding to the second slider 15. The second slider 15 can slide on the piezoelectric wafer 4 and within the groove 16. A connecting rod 17 is provided at the bottom of the second slider 15, and the outer end of the connecting rod 17 is fixedly connected to a lifting platform 18. The lifting platform 18 is fitted onto a sliding shaft 19, and the lifting platform 18 can move up and down on the sliding shaft 19. The up and down movement of the lifting platform 18 on the sliding shaft 19 is controlled by the connecting rod 17. 7 drives the second slider 15 to slide on the piezoelectric wafer 4 and in the slide groove 16, thereby changing the position of the second slider 15 on the piezoelectric wafer 4. The top end of the slide shaft 19 is fixedly connected to the bottom surface of the fixed seat 9 in the middle part of the housing 2 chassis 20. An adjusting nut 21 is installed on the slide shaft 19 at the bottom of the lifting platform 18. The set position of the lifting platform 18 on the slide shaft 19 can be adjusted by adjusting the nut 21. A limit ring 22 is installed on the slide shaft 19 below the adjusting nut 21 for limiting the adjusting nut 21.

[0049] Working principle of the invention:

[0050] The piezoelectric multi-degree-of-freedom actuator based on variable modal resonance drive provided by this invention supplies power to the piezoelectric crystals 4. The displacement of the piezoelectric crystals 4 is adjusted by regulating the frequency, amplitude, and mode shape of the power supply. The displacement of the piezoelectric crystals 4 is amplified by the lever fulcrum of the second slider 15 mounted on the piezoelectric crystals 4 and then transmitted to the drive rod 12 at the outer end of the piezoelectric crystals 4, thereby achieving the purpose of controlling the actuator's displacement. By adjusting the phase of the power supply to control the actuator's motion mode, it is possible to achieve both vertical linear vibration and oscillating motion around the spherical hinge head 6 at any angle, and simultaneously superimpose both motions. Furthermore, the four piezoelectric crystals 4 can clamp the motion, maintaining a high holding force even when the power is off.

[0051] Each piezoelectric crystal 4 has an adjustment groove 13 to change the mass of the piezoelectric crystal 4. The mass of the system can be increased or decreased by adding or removing the frequency conversion screw 14, and the position of the frequency conversion screw 14 in the adjustment groove 13 can be adjusted to change the natural frequency of the piezoelectric crystal 4.

[0052] The drive disk 1 is connected to the spherical hinge head 6. The drive disk 1 can not only achieve linear vibration, but also swing around the spherical hinge head 6 at any angle, and can play a role in occasions where angle positioning is required (such as lens deflection angle control).

[0053] Four piezoelectric crystals 4 are arranged symmetrically in a cross shape, grouped in pairs. Each piezoelectric crystal 4 is independently powered. Due to the inverse piezoelectric effect, when an alternating current is applied to a piezoelectric crystal 4, it will vibrate. The vibration displacement of the piezoelectric crystal 4 can be transmitted to the drive disk 1 with a certain amplification ratio, thereby realizing the driving function. The displacement amplification function is realized by the second slider 15. Adjusting the position of the lifting platform 18 can adjust the displacement amplification ratio. At the same time, a frequency conversion screw 14 can be added to change the natural frequency of the piezoelectric crystal 4.

[0054] The specific work process is as follows:

[0055] Linear displacement: When the amplitude, frequency, and phase of the alternating power supply for the four piezoelectric crystals 4 are all the same, the displacement modes of the four piezoelectric crystals 4 are the same. Therefore, the same displacement will be transmitted on the drive rod 12, causing the drive disk 1 to move up and down in a linear motion. The displacement of the drive disk 1 can be controlled by adjusting the power supply mode.

[0056] Swing displacement: The attitude of the drive disk 1 in three-dimensional space is controlled by the cooperation of four slide rails 10. If the phase difference of the electrical phase of the two opposing piezoelectric crystals 4 is T / 2 (T is the minimum positive period of the alternating power supply vibration), and all other parameters are the same, the displacement directions of the piezoelectric crystals 4 are opposite. Therefore, the drive disk 1 will tilt towards the drive rod 12 with the displacement direction downward. Similarly, by adjusting the power supply of the other two opposing piezoelectric crystals 4 at the same time, the tilt angle of the drive disk 1 in another direction can be adjusted, thereby enabling the drive disk 1 to swing around the spherical hinge head 6 at any angle.

Claims

1. A piezoelectric multi-degree-of-freedom actuator based on variable modal resonance drive, comprising a drive disk, a housing, a base, a drive mechanism, and a piezoelectric wafer, wherein the housing is mounted on the base, the drive disk is located at the top of the housing, the drive mechanism and the piezoelectric wafer are integrated in the inner cavity of the housing, the piezoelectric wafer is connected to the drive mechanism, and the piezoelectric wafer drives the drive disk to perform vertical linear motion and oscillation at arbitrary angles and directions through the drive mechanism, characterized in that: The bottom of the drive disk is provided with a cross-shaped intersecting slide rail. The first slider on the drive mechanism is engaged with the slide rail and can slide along the slide rail. The drive mechanism includes a first slider and a drive rod. The first slider is assembled at the top of the drive rod and is engaged with the slide rail at the bottom of the drive disk. The bottom of the drive rod is fixed to a piezoelectric crystal. The vibration of the piezoelectric crystal causes the drive rod to drive the first slider to slide along the slide rail at the bottom of the drive disk. Four piezoelectric crystals are assembled. The four piezoelectric crystals are arranged in pairs in a cross shape. The cross-shaped piezoelectric crystals correspond to the cross-shaped slide rails at the bottom of the drive disk. The inner ends of the four piezoelectric crystals are fixed to a fixed seat at the center of the housing chassis, and the outer ends of the four piezoelectric crystals are fixed to the drive rod on the drive mechanism. The drive rod on the drive mechanism and the piezoelectric crystals are connected to the drive rod. Four piezoelectric crystals are also assembled accordingly; each piezoelectric crystal is fitted with a second slider, and a groove is opened on the chassis of the housing corresponding to the position of the second slider. The second slider can slide on the piezoelectric crystal and in the groove. A connecting rod is set at the bottom of the second slider, and the outer end of the connecting rod is fixed to the lifting platform. The lifting platform is fitted on the sliding shaft, and the lifting platform can move up and down on the sliding shaft. The up and down movement of the lifting platform on the sliding shaft drives the second slider to slide on the piezoelectric crystal and in the groove through the connecting rod, thereby changing the position of the second slider on the piezoelectric crystal. The top of the sliding shaft is fixed to the bottom surface of the fixed seat in the middle of the chassis of the housing. An adjusting nut is installed on the sliding shaft at the bottom of the lifting platform. The set position of the lifting platform on the sliding shaft can be adjusted by adjusting the nut. A limit ring is installed on the sliding shaft below the adjusting nut for limiting the adjustment of the nut.

2. The piezoelectric multi-degree-of-freedom actuator based on variable modal resonance drive according to claim 1, characterized in that: The center part of the bottom of the drive disk is hinged to the spherical hinge head through a hinge head cap. The drive disk can swing at any angle on the spherical hinge head. The straight rod at the bottom of the spherical hinge head is screwed to the connecting shaft below. The straight rod at the bottom of the spherical hinge head is fitted with a hinge head seat, which is wrapped around the lower part of the spherical hinge head. The connecting shaft below the spherical hinge head is inserted into the center hole of the fixing seat at the center of the housing chassis. The connecting shaft can slide within the center hole of the fixing seat.

3. The piezoelectric multi-degree-of-freedom actuator based on variable modal resonance drive according to claim 1, characterized in that: Each piezoelectric wafer has an adjustment groove near the mounting base. A frequency conversion screw is installed in the adjustment groove. The natural frequency of the piezoelectric wafer can be adjusted by increasing or decreasing the number of frequency conversion screws and adjusting the position of the frequency conversion screws in the adjustment groove.

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