Linear low-frequency active dynamic vibration absorber and planar arrangement method

Abstract

The application discloses a linear low-frequency active dynamic vibration absorber and a planar arrangement method, and relates to the technical field of mechanical arm control technology. The carbon fiber base is provided with three carbon fiber sensor fixing seats which are connected to the periphery through bolts, the three carbon fiber sensor fixing seats are arranged in an array with the center of the carbon fiber base as the center, a laser displacement sensor is installed outside the carbon fiber sensor fixing seat, an acceleration sensor is fixedly connected to the center position of the carbon fiber base, and a winding assembly is installed between each acceleration sensor and the laser displacement sensor. The application designs a new dynamic vibration absorber scheme, compared with the traditional linear dynamic vibration absorber, the force synthesis and planar distribution form are related and diverse, so that the vibration suppression force synthesis is more accurate, the vibration suppression effect is more outstanding, the quality is lighter, the stroke is smaller, and the additional vibration caused by the increase of the vibration absorber is reduced.

Description

Technical Field

[0001] This invention relates to the field of robotic arm control technology, and in particular to a linear low-frequency active power vibration absorption device and a planar arrangement method. Background Technology

[0002] In the application of flexible robotic arms, end-effector vibration is a particularly prominent issue. Firstly, due to the elastic deformation of the robotic arm links, especially under abrupt changes in motion or excessive acceleration, the end-effector experiences severe oscillations, affecting its positioning accuracy and stability. Secondly, the joint drive torque of the robotic arm is typically provided by a harmonic reducer, whose inherent flexibility causes a certain degree of deformation in the joints under load. This flexibility effect affects torque transmission and may lead to instability in joint control. When the joint flexibility is high, the torque output in the transmission system may lag or change irregularly, resulting in additional vibrations at the end-effector.

[0003] Among the vibration suppression strategies for flexible robotic arms, the most typical example is the dynamic vibration absorber. Currently, proportional electromagnetic active vibration absorbers with a "shear-type" magnetic pole surface structure have a certain effect on suppressing harmonic periodic excitation forces, but their vibration frequency differs significantly from their own resonant frequency range, resulting in insufficient driving force and ineffective control of acceleration response at 50Hz. Ground-hook control strategies based on displacement and velocity have better vibration reduction effects, but the external excitation involved is time-invariant harmonic excitation, with a limited frequency variation range. Meanwhile, for the low-frequency vibration of space robotic arms, the traditional linear motion dynamic vibration absorber solution will result in long strokes and heavy weight, leading to numerous end-effector vibration problems in flexible robotic arms in low-frequency scenarios. Summary of the Invention

[0004] The purpose of this invention is to provide a linear low-frequency active power vibration absorption device and a planar arrangement method and system to solve the problem of end-effector vibration in existing flexible robotic arms.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A linear low-frequency active power vibration absorption device includes: a carbon fiber base, wherein the carbon fiber base is bolted to three carbon fiber sensor mounting bases, the three carbon fiber sensor mounting bases are arranged in an array with the center of the carbon fiber base as the center, a laser displacement sensor is installed on the outside of the carbon fiber sensor mounting base, an acceleration sensor is fixedly connected to the center of the carbon fiber base, and a winding assembly is installed between each acceleration sensor and the laser displacement sensor.

[0007] Furthermore, the winding assembly includes two carbon fiber shaft holders, and a carbon fiber shaft is fixedly connected between the two carbon fiber shaft holders.

[0008] Furthermore, both the carbon fiber base and the carbon fiber shaft are made of T300 carbon fiber, which can work normally at high temperatures of 120℃-180℃. It has 8 times the tensile strength of ordinary steel, a higher elastic modulus than steel, excellent impact resistance, and is not easily oxidized. Moreover, steel has 3.9 times the mass of carbon fiber material of the same volume.

[0009] Furthermore, the carbon fiber base serves as the base plate of the vibration absorber, with a thickness of 5mm and a base plate area of ​​544cm². 2 The carbon fiber shaft is wound with copper wire on the outer layer and contains a 304 stainless steel spring and an N52 neodymium iron boron magnet inside. The mover stroke is 50mm.

[0010] Furthermore, the bare diameter of the enameled wire in the copper wire winding is 0.5mm, the winding direction is counterclockwise from the main axis, the wire ends are left with a length of 150mm, it is wound in three layers, and is bonded with 500mpa·s adhesive. The temperature resistance range is -55℃ to 125℃.

[0011] Furthermore, the laser displacement sensor has a detection range of 35-65mm, a detection accuracy of 30um, and a single mass of 85g, making it small in size and light in weight. The internal piezoelectric crystal impedance converter circuit of the accelerometer converts the charge generated by the vibrating element during impact or vibration into a voltage output, which is then connected and fixed to the carbon fiber base through the bottom threaded hole.

[0012] Furthermore, a carbon fiber robotic arm connector is fixed to the bottom of the carbon fiber base. Both the carbon fiber sensor mounting base and the carbon fiber robotic arm connector are non-standard parts. The carbon fiber shaft mounting base is made of carbon fiber reinforced modified nylon material.

[0013] Furthermore, a planar arrangement method for a linear low-frequency active dynamic vibration absorption device includes:

[0014] GVOLT linear DC power supplies, power amplifiers, linear low-frequency vibration absorbers, accelerometers, laser displacement sensors, KISTLER 5134 piezoelectric couplers, PCI-6221 adapter terminal blocks, NI PCI-6221 multifunction data acquisition cards, and Linux real-time operating systems.

[0015] The Gowe linear DC power supply provides ±24V to the power amplifier, which is connected to a linear low-frequency vibration absorber with a controlled current range of ±3A. The accelerometer in the linear low-frequency vibration absorber senses the jitter from the robotic arm and converts the generated charge into voltage. This voltage is then transmitted to the component's Linux real-time operating system via a KISTLER 5134 piezoelectric coupler, a PCI-6221 adapter terminal block, and an NI PCI-6221 multifunction acquisition card for FFT spectrum analysis.

[0016] Furthermore, the vibration spectrum of the robotic arm obtained after FFT spectrum analysis needs to be subjected to damping forces of the same frequency but opposite direction. These forces are then transmitted via an NI PCI-6221 multifunction data acquisition card and a PCI-6221 adapter board, through a power amplifier to output corresponding currents to the three sets of copper wire windings. The N52 neodymium iron boron magnets in the carbon fiber shaft cylinder move under the influence of the current, causing the 304 stainless steel springs to stretch and compress accordingly. The following applies to each axis:

[0017] and ,

[0018] The resulting damping force is applied to the entire vibration absorber to dampen the vibration of the robotic arm. The laser displacement sensor records the position of the magnet in the shaft cylinder at a cycle of one-thousandth of a second. The magnitude and direction of the current output by the power amplifier are controlled in a closed loop by the control algorithm built into the Linux real-time operating system.

[0019] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0020] This invention addresses low-frequency vibrations at the end of robotic arms by designing a novel dynamic vibration absorber solution. Compared to traditional linear dynamic vibration absorbers, the force synthesis is related to and diverse in planar distribution, resulting in more accurate vibration damping force synthesis and better vibration damping effect in different scenarios. At the same time, it is lighter and has a shorter stroke, reducing the additional vibration caused by adding a vibration absorber. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a linear low-frequency active power vibration absorption device provided in an embodiment of the present invention;

[0022] Figure 2 This is a half-sectional schematic diagram of a linear low-frequency active power vibration absorption device provided in an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the internal structure of a carbon fiber shaft cylinder for a linear low-frequency active power vibration absorption device provided in an embodiment of the present invention;

[0024] Figure 4This is a platform connection diagram of a planar arrangement method for a linear low-frequency active power vibration absorption device provided in an embodiment of the present invention;

[0025] Figure 5 This is a schematic flowchart of a planar arrangement method for a linear low-frequency active power vibration absorption device provided in an embodiment of the present invention.

[0026] The components include: 1. Laser displacement sensor; 2. Carbon fiber shaft holder; 3. Accelerometer; 4. Carbon fiber base; 5. Copper wire winding; 6. Carbon fiber sensor holder; 7. Carbon fiber robotic arm connector; 8. 304 stainless steel spring; 9. N52 neodymium iron boron strong magnet; 10. Carbon fiber shaft; 11. Gowe linear DC power supply; 12. Power amplifier; 13. Linear low-frequency vibration absorber; 16. KISTLER 5134 piezoelectric coupler; 17. PCI-6221 adapter terminal block; 18. NI PCI-6221 multi-function data acquisition card; 19. Linux real-time operating system. Detailed Implementation

[0027] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely intended to explain the present invention and not to limit the present invention. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present invention by illustrating examples of the invention.

[0028] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0029] In the embodiments of the present invention, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of the present invention shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on the present invention; the term "multiple" in the present invention refers to two or more (including two).

[0030] Within a plane, it can be divided into various combined structures according to its distribution pattern. Please refer to [reference needed]. Figure 2 The multi-axis distributed topology diagram shows the coil movers uniformly distributed in the plane at angles of 120°, 90°, and 72°. The vibration suppression output force originates from the Ampere force generated by the coil movers on each axis. In the Cartesian coordinate system, the distance between the coil movers and the center point is R, and the output forces on each axis are F1, F2, F3, F4, and F5 (equal to the number of axes). The components of their resultant force in the X and Y axes are as follows:

[0031] (a) (b)

[0032] (c)

[0033] The vibration damping force output by the system is the resultant force of the X and Y components, following the... The triaxial resultant force in the θ direction is Apart from differences in the distribution method and the calculation of the resultant force, the structure and control are basically the same. Taking the triaxial type as an example (hereinafter referred to as the linear low-frequency vibration absorber) for a physical introduction.

[0034] Please refer to Figure 1 The carbon fiber base 4 and carbon fiber shaft 10 of the linear low-frequency dynamic vibration absorber 13 are both made of T300 carbon fiber, which can operate normally at high temperatures of 120℃-180℃. It has 8 times the tensile strength of ordinary steel, a superior elastic modulus, excellent impact resistance, and is not easily oxidized. Furthermore, steel has 3.9 times the mass of carbon fiber for the same volume. The former serves as the absorber's base plate, with a thickness of 5mm and a base plate area of ​​544cm². 2 The latter has an outer layer of copper wire winding 5, and an internal component consisting of a 304 stainless steel spring 8 and an N52 neodymium iron boron strong magnet 9. The mover stroke is 50mm, which constitutes the main actuating part of the vibration absorber for vibration suppression.

[0035] Please refer to Figure 3 The bare diameter of the enameled wire in the copper wire winding 5 is 0.5mm. The winding direction is counterclockwise from the main axis. The wire ends are left with a length of 150mm. It is wound in three layers and bonded with 500mpa·s adhesive. The temperature resistance range is -55℃ to 125℃, which meets the requirements of the working environment.

[0036] The laser displacement sensor 1 has a detection range of 35-65mm, a detection accuracy of 30um, and a single mass of 85g. It is small in size and light in weight. It is fixed to the carbon fiber base 4 by bolting through the carbon fiber sensor mounting bracket 6. The accelerometer 3 has excellent long-term stability, repeatability and measurement accuracy. It has low thermal sensitivity (temperature coefficient of 0.04%) and low substrate strain. The internal piezoelectric crystal impedance converter circuit converts the charge generated by the vibrating element during impact or vibration into voltage output. It is fixed to the carbon fiber base 4 through the bottom threaded hole.

[0037] The carbon fiber shaft cylinder fixing seat 2, carbon fiber sensor fixing seat 6, and carbon fiber robotic arm connector 7 are non-standard parts, requiring high material strength and designability. Besides connecting and fixing to the base plate and robotic arm, the carbon fiber shaft cylinder fixing seat 2 also needs to ensure a high elastic modulus so that the damping force generated by the actuating part of the vibration absorber is not absorbed. If materials with good plasticity, such as resin, are used to meet the designability requirements, their elastic modulus and strength will be low, making it impossible to guarantee normal operation in small-sized parts. If conventional steel or aluminum is used, the processing cost is high, and due to its large weight, it will add significant external weight to the robotic arm, further affecting its working performance. Therefore, using carbon fiber reinforced modified nylon provides high strength, high modulus, designability, and excellent friction and wear properties. The elastic modulus increases by up to 422%, the strength increases by up to 117%, and the coefficient of friction is between 0.21 and 0.24 (2000 rpm, 20 N). It is also lightweight, uses lower-priced raw materials, and is easy to mold and process.

[0038] Please refer to Figure 4 A control platform constructed using a planar arrangement method for a linear low-frequency active vibration damping device is provided. The platform's Gowe linear DC power supply 11 supplies ±24V to the power amplifier 12, which is connected to the linear low-frequency vibration damper 13. The current range is controlled to ±3A. The accelerometer 3 in the linear low-frequency vibration damper 13 senses the vibration from the robotic arm and converts the generated charge into voltage. This voltage is transmitted through a KISTLER 5134 piezoelectric coupler 16, a PCI-6221 adapter terminal board 17, and an NI PCI-6221 multifunction acquisition card 18 to the component's Linux real-time operating system 19 for FFT spectrum analysis. The vibration spectrum of the robotic arm obtained after FFT spectrum analysis requires the application of damping forces with the same frequency but opposite direction. These forces are then transmitted via the NI PCI-6221 multifunction acquisition card 18 and the PCI-6221 adapter terminal board 17, and through the power amplifier 12, corresponding currents are output to the three sets of copper wire windings. The N52 neodymium iron boron strong magnet 9 in the carbon fiber shaft cylinder 10 moves under the influence of the current, causing the 304 stainless steel spring 8 to stretch and compress accordingly. The following applies to each shaft:

[0039] and ,

[0040] The resulting damping force is applied to the entire vibration absorber to complete the vibration damping of the robotic arm. The laser displacement sensor 1 records the position of the magnet in the shaft cylinder at a period of one-thousandth of a second. The magnitude and direction of the current output by the power amplifier 12 are controlled in a closed loop by the control algorithm built into the Linux real-time operating system 9.

[0041] Please refer to Figure 5 The robotic arm control first obtains the low-frequency vibration characteristics of the main structure through excitation testing. Based on this, the vibration-absorbing mass, stiffness, and damping are initially selected, and the mechanical design of the passive vibration absorber integrating linear guide rail, spring, damping, and mass is completed. After verifying the frequency and attenuation effect using finite element method, the position and angle of the vibration absorber are optimized in a multi-objective manner within the given planar area of ​​the equipment, with the objectives of avoiding collision with the mounting holes, minimizing the added mass, and minimizing the kinetic energy of the main structure. Subsequently, a voice coil motor, laser displacement, and acceleration sensors are integrated into the vibration absorber, and a fuzzy RBF adaptive PID algorithm is run in the embedded real-time system to achieve active force compensation in addition to passive parameters. Finally, the passive and active parameters are calibrated and the whole assembly is put back into the main equipment for working condition verification to further suppress linear vibration.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A linear low-frequency active dynamic vibration absorber comprising: The carbon fiber base (4) is characterized in that the carbon fiber base (4) is bolted to the outside of three carbon fiber sensor fixing seats (6), the three carbon fiber sensor fixing seats (6) are arranged in an array with the center of the carbon fiber base (4) as the center, a laser displacement sensor (1) is installed on the outside of the carbon fiber sensor fixing seat (6), an acceleration sensor (3) is fixedly connected to the center of the carbon fiber base (4), and a winding assembly is installed between each acceleration sensor (3) and the laser displacement sensor (1); The winding assembly includes two carbon fiber shaft holders (2), and a carbon fiber shaft (10) is fixedly connected between the two carbon fiber shaft holders (2). The carbon fiber base (4) and carbon fiber shaft (10) are both made of T300 carbon fiber, which can work normally at high temperatures of 120℃-180℃. It has 8 times the tensile strength of ordinary steel, better elastic modulus than steel, excellent impact resistance, and is not easily oxidized. Moreover, steel is 3.9 times the mass of carbon fiber material in the same volume. The carbon fiber base (4) is used as a vibration absorber bottom plate, with a thickness of 5 mm and a bottom plate area of 544 cm 2 The carbon fiber shaft cylinder (10) is wrapped with a copper wire winding (5) on the outer layer, and contains a 304 stainless steel spring (8) and a component N52 neodymium iron boron strong magnet (9) in the inner layer. The mover stroke is 50 mm.

2. The linear low-frequency active dynamic vibration absorber according to claim 1, characterized in that: The bare wire diameter of the enameled wire in the copper wire winding (5) is 0.5mm, the winding direction is counterclockwise from the main axis, the wire head and tail are left with a length of 150mm, it is wound in three layers, and is bonded with 500mpa·s adhesive. The temperature range is -55℃ to 125℃.

3. The linear low-frequency active dynamic vibration absorber according to claim 1, characterized in that: The laser displacement sensor (1) has a detection range of 35-65mm, a detection accuracy of 30um, a single mass of 85g, and is small in size and light in weight. The internal piezoelectric crystal impedance converter circuit of the acceleration sensor (3) converts the charge generated by the vibration element during impact or vibration into voltage output, and is connected and fixed to the carbon fiber base (4) through the bottom threaded hole.

4. The linear low-frequency active dynamic vibration absorber according to claim 1, characterized in that: The bottom of the carbon fiber base (4) is fixed with a carbon fiber robotic arm connector (7). Both the carbon fiber sensor mounting base (6) and the carbon fiber robotic arm connector (7) are non-standard parts. The carbon fiber shaft mounting base (2) is made of carbon fiber reinforced modified nylon material.

5. The planar arrangement method of the linear low-frequency active dynamic vibration absorber according to any one of claims 1 to 4, characterized in that, include: The components include: a linear DC power supply (11), a power amplifier (12), a linear low-frequency vibration absorber (13), an accelerometer (3), a laser displacement sensor (1), a KISTLER 5134 piezoelectric coupler (16), a PCI-6221 adapter terminal block (17), an NI PCI-6221 multi-function data acquisition card (18), and a Linux real-time operating system (19). The Goodwell linear DC power supply (11) supplies ±24V to the power amplifier (12). The power amplifier (12) is connected to the linear low-frequency vibration absorber (13) and controls the current range to ±3A. The acceleration sensor (3) in the linear low-frequency vibration absorber (13) senses the vibration from the robotic arm and converts the generated charge into voltage. The voltage is transmitted to the component Linux real-time operating system (19) for FFT spectrum analysis through the KISTLER 5134 piezoelectric coupler (16), PCI-6221 adapter terminal board (17), and NI PCI-6221 multi-function acquisition card (18).

6. The planar arrangement method of the linear low-frequency active dynamic vibration absorber according to claim 5, characterized in that: The vibration spectrum of the mechanical arm obtained by FFT spectrum analysis needs to apply frequency same and opposite direction vibration suppression force, and through the NI PCI-6221 multifunctional acquisition card (18), PCI-6221 adapter terminal board (17), the corresponding current is output by the power amplifier (12) to the three groups of copper wire winding; the N52 neodymium iron boron strong magnet (9) in the carbon fiber shaft cylinder (10) moves under the action of the current, and the 304 stainless steel spring (8) is correspondingly stretched and compressed, and each shaft follows: with , The generated vibration suppression resultant force acts on the whole vibration absorber to complete the vibration suppression of the mechanical arm, the laser displacement sensor (1) records the position of the magnet in the shaft cylinder at a period of one thousandth of a second, and the current size and direction output by the power amplifier (12) are closed-loop controlled through the control algorithm built in the Linux real-time operating system (19).

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