A Two-Degree-of-Freedom Active Suppression Method Applied to Mechanical Vibration Systems

Abstract

The present invention discloses a two-degree-of-freedom active suppression device and method applied to a mechanical vibration system. The device includes a vibration active control data acquisition and operation part, a power amplification part, and a vibration active control actuator; the method is as follows: the control software adopted is a core control program based on an adaptive feedback control algorithm built on an FPGA and a vibration active measurement and control software; the core software realizes the calculation of the driving signal of the actuator through the control algorithm, and the vibration active measurement and control software completes functions such as vibration signal detection, test process debugging, and communication coordination control; compared with the existing vibration control technology, the present invention has no complex and cumbersome mechanical actuators, has a simple structure and a fast response speed, and can perform real-time high-precision control through the signal provided by the control system; compared with the existing vibration control technology, the control system of the present invention adopts a filter adaptive control algorithm and digital signal processing technology, has high sensitivity, and the control process is reliable and stable.

Description

Technical Field

[0001] The present invention specifically relates to the technical field of mechanical vibration suppression, and more specifically, it is a two-degree-of-freedom active suppression method applied to a mechanical vibration system. Background Art

[0002] The magnitude of vibration is an important factor affecting the performance of mechanical equipment. Effectively reducing mechanical vibration is undoubtedly of great significance for improving the performance of mechanical equipment. In actual engineering, a series of methods including vibration absorption, vibration isolation, vibration elimination, vibration damping, and structural modification are adopted for structural vibration reduction. These methods can be classified into active control and passive control of vibration. Passive control does not require the input of external energy, and the vibration damping device has a simple structure, is easy to implement, and has the characteristics of economy and reliability. Therefore, it has been widely used in actual engineering. However, passive vibration damping has natural insurmountable defects. For example, when the structure of the vibration damping system is determined, the vibration damping effect is also determined. For vibrations caused by excitation forces with changing external disturbance frequencies, the vibration damping effect is not good. With the increasing requirements for vibration control accuracy, people began to seek new and more effective vibration damping technologies. At this time, the active vibration control technology has become the focus of attention because of its advantages such as good vibration damping effect and wide effective vibration damping frequency band. Usually, the vibration of a mechanical system is within a certain frequency band, and the vibration also exists in multiple directions. According to the theory of mechanical vibration, multi-directional variable-frequency vibration requires two or more dynamic vibration damping devices to achieve efficient vibration damping under complex excitation conditions. However, the previous dynamic vibration damping devices are mostly single-axial, and the vibration damping efficiency is limited. Based on this demand, the present invention proposes a two-degree-of-freedom active vibration control device applicable to mechanical vibration.

[0003] The existing CN108155773B is a tunable two-degree-of-freedom active vibration control device, which consists of a housing, a resonance device, a natural frequency adjustment device, an energy dissipation device, etc. The resonance device includes a permanent magnet, a magnet, and a flexible connecting rod connecting them; the natural frequency adjustment device consists of a stepping motor, a bidirectional ball screw, a movable support beam, etc. In CN108155773B, the natural frequency adjustment device receives real-time signals from the acceleration sensor in the unit. After being calculated and processed by the DSP of the control system, the control system adjusts the stepping motor, and further drives the ball screw to adjust the vibration length of the flexible connecting rod participating in the vibration, so as to achieve the purpose of changing the natural frequency and realizing the vibration control of the vibration damping object.

[0004] However, since the vibration control device has a relatively large number of mechanical structures and the actuator is also relatively complex during the active vibration control process, the uncontrollability and non-linearity of the transfer function of the entire system increase significantly, resulting in an increase in the control difficulty and precision of the system. In addition, due to the influence of various factors such as the deformation during the movement of the bidirectional ball screw, the machining accuracy of components, and the precise control of the rotation of the stepping motor, the control accuracy of the entire self-tuning two-degree-of-freedom electromagnetic vibration absorber system will also be affected, which is not conducive to the precise control of micro-amplitude vibrations. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a two-degree-of-freedom active suppression method applied to a mechanical vibration system.

[0006] A two-degree-of-freedom active suppression method applied to a mechanical vibration system, which is applied to a two-degree-of-freedom active suppression device of a mechanical vibration system, including an active vibration control data acquisition and operation part, a power amplification part, and an active vibration control actuator, wherein:

[0007] The active vibration control data acquisition and operation part includes two three-axis acceleration sensors, a controller, and a computer with control software;

[0008] The power amplification part includes an auxiliary power supply and a multi-channel power amplifier;

[0009] The active vibration control actuator includes a housing, and a permanent magnet mover assembly is arranged in the housing. The number of the permanent magnet mover assemblies is three, one is vertically arranged, and the other two are horizontally arranged on both sides. The housing is divided into 3 chambers by a high-permeability outer shell, and each chamber is provided with a permanent magnet mover assembly; the permanent magnet mover assembly includes a permanent magnet mover and a smooth guide rod. The smooth guide rod passes through the permanent magnet mover and can slide relatively. A spring is sleeved on the smooth guide rod. One end of the spring is connected to the inner wall of the housing, and the other end is connected to a connection lock nut; both ends of the smooth guide rod are fixed to the inner wall of the housing. An electromagnetic coil is arranged around the permanent magnet mover. When the electromagnetic coil is energized, an alternating magnetic field is formed, and the permanent magnet mover moves up and down under the action of the alternating magnetic field and outputs acceleration; the acceleration sensor is of the IEPE type; an electromagnetic coil support frame is arranged around the permanent magnet mover, and an electromagnetic coil is arranged on the electromagnetic coil support frame;

[0010] The two-degree-of-freedom active suppression method applied to a mechanical vibration system is as follows:

[0011] The control software adopted is a core control program and an active vibration measurement and control software based on an adaptive feedback control algorithm built on an FPGA; the core software calculates the driving signal of the actuator through the control algorithm, and the active vibration measurement and control software completes functions such as the detection of vibration signals, the debugging of the test process, and the communication coordination control.

[0012] Specifically, the adopted filter adaptive feedback control algorithm, where P(z) is the transfer function between the external disturbance excitation signal and the vibration response, d(n) is the desired signal under the external disturbance excitation force, and e(n) is the vibration response generated under the working condition of the vibration active control system, that is, the error signal; x(n) is the external disturbance excitation force signal of the controlled object and also serves as the reference input vector of the controller;

[0013] X(n) = [x(n), x(n - 1),..., x(n - L + 1)] T

[0014] The weight vector of the control filter is: W(n) = [w0, w1,..., w l , w L-1 T , where n represents the sampling time and L represents the filter order. Then the output of the controller is:

[0015]

[0016] The error channel is represented by an FIR filter of order H, and its weight vector is:

[0017] S(n) = [s0, s1,..., s H-1

[0018] W(z) and S(z) respectively represent the Z-transforms of the filter weight vector W(n) and the error channel filter S(n). It is the digital estimation of the error channel S(z) obtained by the system identification method before the start of the control process, where

[0019] W(z) = w0 + w1z -1 + w2z -2 + … + w L-1 z -(L-1)

[0020] S(z) = S0 + S1z -1 + S2z -2 + … + S H-1 z -(H-1)

[0021] Then the output of the error sensor can be written as

[0022] e(n) = d(n) - S T Y(n)

[0023]

[0024] By changing the order of summation, we get:

[0025] ​​

[0026] Let

[0027] Then the error signal is:

[0028]

[0029] Define the following vectors:

[0030] X′(n) = [x′(n), x′(n - 1),..., x′(n - L + 1)] T

[0031] The error signal is further written as:

[0032] P(n) = d(n) - X′ T (n)W(n)

[0033] Take the performance function: J = E{e 2 (n)}

[0034] Take the derivative: J = E{d 2 (n) - 2d T (n)X′ T (n)W + W T X′(n)X′ T (n)W}

[0035] According to the derivation process of the standard LMS algorithm, a similar result can also be obtained, that is, the optimal weight vector is:

[0036] W * = [E{X′(n)X′ T (n)}] -1 E{X′(n)d(n)}

[0037] Weight vector update formula:

[0038] W(n + 1) = W(n) + 2μX′(n)e(n)

[0039] Then the x - LMS algorithm of the entire filter is summarized as follows:

[0040]

[0041] e(n) = d(n) - S T Y(n)

[0042] W(n + 1) = W(n) + 2μX′(n)e(n)

[0043] X′(n) = [x′(n), x′(n),..., x′(n - L + 1)] T

[0044]

[0045] In view of the related disadvantages and problems existing in the prior art, such as complex mechanical actuators, slow response speed, and low control accuracy, the present invention proposes a new two-degree-of-freedom electromagnetic coupling vibration control device. Compared with the prior art, the main advantages of the present invention are as follows:

[0046] (1) Compared with the existing vibration control technologies, the present invention does not have complex and cumbersome mechanical actuators, has a simple structure and a fast response speed, and can perform real-time high-precision control through the signals provided by the control system;

[0047] (2) Compared with the existing vibration control technologies, the control system of the present invention adopts a filter adaptive control algorithm and digital signal processing technology, with high sensitivity and a reliable and stable control process;

[0048] (3) Compared with the existing vibration control technologies, the vibration control device involved in the present invention can perform vibration control in two directions simultaneously, and can also perform vibration control in a single direction, providing more diverse control options;

[0049] (4) The present invention effectively integrates three parts: the vibration data acquisition and operation part, the power amplification part, and the mechanical actuator, forming a unitized mode of vibration control;

[0050] (5) In the mechanical actuator designed in the present invention, the reciprocating motion of the inertial mass unit is realized through the principle of electromagnetic induction;

[0051] (6) The present invention adopts a filter adaptive algorithm, and the driving signal obtained through the operation of the controller is amplified by the power amplifier to drive the mechanical actuator, thereby achieving the purpose of vibration control;

[0052] (7) In the mechanical actuator of the vibration control device involved in the present invention, three square-section chambers are designed, and an inertial mass unit is arranged in each section chamber. The directions of the three square-section chambers are perpendicular to each other. Therefore, this structural design ensures that the forces output by the mechanical actuator at all times during the vibration control process are perpendicular to each other and no eccentric torque is generated;

[0053] (8) The mechanical actuator of the vibration control device involved in the present invention is composed of three separate inertial masses. Each mass unit is composed of structures such as permanent magnets and magnetic yokes, forming a double-layer magnetic conduction magnetic field along the direction of the smooth guide rail. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 is a schematic structural diagram of the present invention;

[0055] Figure 2 is Figure 1 the A-A cross-sectional view of;

[0056] Figure 3 is Figure 2 the B-B cross-sectional view of

[0057] Figure 4 is the block diagram of the vibration active suppression system based on the x-LMS algorithm.

[0058] Markings in the figure: 1 - triaxial acceleration sensor, 2 - electromagnetic coil support frame, 3 - electromagnetic coil, 4 - permanent magnet mover, 41 - magnetic conduction pressing block, 5 - locking nut, 6 - spring, 7 - smooth guide rod, 8 - high magnetic permeability housing, 9 - terminal block. Specific implementation manners

[0059] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0060] Embodiment 1

[0061] As Figures 1 to 3 shown, a two-degree-of-freedom active suppression device applied to a mechanical vibration system includes a vibration active control data acquisition and operation part, a power amplification part, and a vibration active control actuator; wherein:

[0062] The vibration active control data acquisition and operation part includes two triaxial acceleration sensors 1, a controller, and a computer with control software;

[0063] The power amplification part includes an auxiliary power supply and a multi-channel power amplifier;

[0064] The vibration active control actuator includes a housing. A permanent magnet mover assembly is arranged inside the housing. The number of the permanent magnet mover assemblies is three. One is vertically arranged, and the other two are horizontally arranged on both sides. The housing is divided into 3 chambers by a high magnetic permeability housing 8, and each chamber is provided with a permanent magnet mover assembly; the permanent magnet mover assembly includes a permanent magnet mover 4 and a smooth guide rod 7. The smooth guide rod 7 passes through the permanent magnet mover 4 and can slide relatively. A spring 6 is sleeved on the smooth guide rod. One end of the spring 6 is connected to the inner wall of the housing, and the other end is connected to the locking nut 5. Both ends of the smooth guide rod 7 are fixed to the inner wall of the housing. An electromagnetic coil 3 is arranged around the permanent magnet mover. When the electromagnetic coil 3 is energized, an alternating magnetic field is formed, and the permanent magnet mover moves up and down under the action of the alternating magnetic field and outputs acceleration to the outside.

[0065] Preferably, the permanent magnet mover consists of a permanent magnet, a magnetic conduction pressing block 41, and a locking nut 5. The permanent magnet is a part of the kinematic pair. The permanent magnet is pressed by the magnetic conduction pressing blocks at both ends and locked from both ends with the locking nut. The entire kinematic pair in the middle is fixed with two upper and lower nuts, and there is a certain gap between the kinematic pair and the middle smooth guide rail.

[0066] Preferably, the acceleration sensor is of IEPE type.

[0067] Preferably, an electromagnetic coil support frame 2 is arranged around the permanent magnet mover 4, and an electromagnetic coil 3 is arranged on the electromagnetic coil support frame.

[0068] The present invention belongs to a two-degree-of-freedom electromagnetic coupling vibration control device, which realizes real-time and precise control of the vibration of a controlled object by receiving a driving signal calculated by a control system; the present invention belongs to a two-degree-of-freedom electromagnetic coupling vibration control device. Compared with traditional passive vibration damping devices, the present invention effectively expands the vibration control frequency band range and improves the vibration control effect; the present invention belongs to a two-degree-of-freedom electromagnetic coupling vibration control device. Compared with traditional vibration absorbers, whether fixed-frequency or tunable vibration absorbers, most of them are unidirectional; while the two-degree-of-freedom electromagnetic coupling vibration control device involved in the present invention is two-degree-of-freedom and can simultaneously suppress vibrations in two-degree-of-freedom directions, greatly reducing the vibration control cost; the present invention belongs to a two-degree-of-freedom electromagnetic coupling vibration control device. In the present invention, two three-axis acceleration sensors are integrally designed inside the mechanical actuator. This design can be used for collecting vibration signals of a controlled object without the need to set up vibration response sensors on the controlled object again, which is of great significance for vibration control in a narrow space and expanding the application of vibration devices.

[0069] Working principle:

[0070] The present invention is generally applied to the vibration control of a two-degree-of-freedom or multi-degree-of-freedom mechanical system. The actuator of the present device is fixedly installed on the vibration control object. Since the vibration active control actuator and the vibration control object are rigidly connected, three-axis acceleration sensors for measuring the vibration response of the controlled object can be integrally built into the internal cavity of the control actuator. When the vibration of the controlled object occurs, the three-axis acceleration sensors sense the vibration signals from the controlled object and transmit them to the controller in real time. After discrete sampling of the signals, the controller calculates and generates a control signal through an adaptive correlation algorithm and transmits it to the power amplifier. After being amplified by the power amplifier, the control signal simultaneously drives the electromagnetic coupling dynamic vibration absorber in the actuator to start working and outputs vibrations with the same amplitude and opposite phase as the external disturbance excitation in real time, so as to achieve the purpose of suppressing vibration.

[0071] Embodiment 2

[0072] As Figure 3As shown in the figure, a two-degree-of-freedom active suppression method applied to a mechanical vibration system is as follows: The control software adopted includes a core control program based on an adaptive feedback control algorithm and a vibration active measurement and control software built on an FPGA; the core software calculates the driving signal of the actuator through the control algorithm, and the vibration active measurement and control software completes functions such as vibration signal detection, test process debugging, and communication coordination control;

[0073] Specifically, for the adopted filter adaptive feedback control algorithm, P(z) is the transfer function between the external disturbance excitation signal and the vibration response, d(n) is the desired signal under the external disturbance excitation force, and e(n) is the vibration response generated under the working condition of the vibration active control system, that is, the error signal; x(n) is the external disturbance excitation force signal of the controlled object and also serves as the reference input vector of the controller;

[0074] X(n) = [x(n), x(n - 1),..., x(n - L + 1)] T The weight vector of the control filter is: W(n) = [w0, w1,..., w l , w L-1 T , where n represents the sampling time and L represents the filter order, then the output of the controller is:

[0075]

[0076] The error channel is represented by an H-order FIR filter, and its weight vector is:

[0077] S(n) = [s0, s1,..., s H-1 T

[0078] W(z) and S(z) respectively represent the Z-transforms of the filter weight vector W(n) and the error channel filter S(n), is the digital estimate of the error channel S(z) obtained by the system identification method before the start of the control process, where

[0079] W(z) = w0 + w1z -1 + w2z -2 + … + w L-1 z -(L-1)

[0080] S(z) = S0 + S1z -1 + S2z -2 + … + S H-1 z -(H-1)

[0081] Then the output of the error sensor can be written as

[0082] e(n) = d(n) - S​​T Y(n)

[0083]

[0084] By changing the order of summation, we get:

[0085]

[0086] Let

[0087] Then the error signal is:

[0088]

[0089] Define the following vectors:

[0090] X′(n) = [x′(n), x′(n - 1),..., x′(n - L + 1)] T

[0091] The error signal can be further written as:

[0092] e(n) = d(n) - X′ T (n)W(n)

[0093] Take the performance function: J = E{e 2 (n)}

[0094] Take the derivative: J = E{d 2 (n) - 2d T (n)X′ T (n)W + W T X′(n)X′ T (n)W}

[0095] According to the derivation process of the standard LMS algorithm, a similar result can also be obtained, that is, the optimal weight vector is: W* = [E{X′(n)X′ T (n)}]-1E{X′(n)d(n)}

[0096] Weight vector update formula:

[0097] W(n + 1) = W(n) + 2μX′(n)e(n)

[0098] Then the x-LMS algorithm of the entire filter is summarized as follows:

[0099]

[0100] e(n) = d(n) - S T Y(n)

[0101] W(n + 1) = W(n) + 2μX′(n)e(n)

[0102] X′(n) = [x′(n), x′(n),..., x′(n - L + 1)] T

[0103]

[0104] The following points should be noted: First, in the description of this application, it should be noted that unless otherwise specified and defined, the terms "installed", "connected", and "linked" should be understood in a broad sense. It can be a mechanical connection or an electrical connection, or it can be the communication inside two components. It can be directly connected. "Up", "down", "left", "right", etc. are only used to represent the relative position relationship. When the absolute position of the object being described changes, the relative position relationship may change;

[0105] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A two - degree - of - freedom active suppression method applied to a mechanical vibration system, characterized in that, This method is applied to a two-degree-of-freedom active suppression device for a mechanical vibration system, which includes an active vibration control data acquisition and operation part, a power amplification part, and an active vibration control actuator; specifically: The active vibration control data acquisition and operation part includes two three-axis acceleration sensors, a controller, and a computer with control software; The power amplification part includes an auxiliary power supply and a multi-channel power amplifier; The active vibration control actuator includes a housing, in which a permanent magnet mover assembly is arranged. There are three permanent magnet mover assemblies, one is vertically arranged, and the other two are horizontally arranged on both sides. The housing is divided into 3 chambers by a high-permeability outer shell, and each chamber is provided with a permanent magnet mover assembly; the permanent magnet mover assembly includes a permanent magnet mover and a smooth guide rod. The smooth guide rod passes through the permanent magnet mover and can slide relatively. A spring is sleeved on the smooth guide rod. One end of the spring is connected to the inner wall of the housing, and the other end is connected to a connection locking nut; both ends of the smooth guide rod are fixed on the inner wall of the housing. An electromagnetic coil is arranged around the permanent magnet mover. When the electromagnetic coil is energized, an alternating magnetic field is formed, and the permanent magnet mover moves up and down under the action of the alternating magnetic field, outputting acceleration externally; the acceleration sensor is of the IEPE type; an electromagnetic coil support frame is arranged around the permanent magnet mover, and an electromagnetic coil is arranged on the electromagnetic coil support frame; The two-degree-of-freedom active suppression method applied to the mechanical vibration system is as follows: The control software adopted is a core control program based on an adaptive feedback control algorithm and an active vibration measurement and control software built on an FPGA; the core software realizes the calculation of the driving signal of the actuator through the control algorithm, and the active vibration measurement and control software completes functions such as vibration signal detection, test process debugging, and communication coordination control; Specifically, the filtering adaptive feedback control algorithm is adopted. P(z) is the transfer function between the external disturbance excitation signal and the vibration response, d(n) is the desired signal under the external disturbance excitation force, e(n) is the vibration response generated when the active vibration control system works, that is, the error signal; x(n) is the external disturbance excitation force signal of the controlled object, and it is also used as the reference input vector of the controller; X(n) = [x(n), x(n - 1),..., x(n - L + 1)] T The weight vector of the control filter is: W(n) = [w0, w1,..., w l , w L-1 T , where n represents the sampling time and L represents the filter order. Then the output of the controller is:​ The error channel is represented by an H-order FIR filter, and its weight vector is: S(n) = [s0, s1,..., s H-1 ​ $W(z)$ and $S(z)$ represent the Z-transforms of the filter weight vector $W(n)$ and the error channel filter $S(n)$ respectively, which is the digital estimate of the error channel $S(z)$ obtained by the system identification method before the control process starts, where W(z) = w0 + w1z -1 + w2z -2 + … + w L-1 z -(L-1) S(z) = S0 + S1z -1 + S2z -2 + … + S H-1 z -(H-1) Then the output of the error sensor can be written as e(n) = d(n) - S T Y(n) By changing the order of summation, we get: Let Then the error signal is: Define the following vectors: X′(n) = [x′(n), x′(n - 1),..., x′(n - L + 1)] T The error signal can be further written as: e(n) = d(n) - X′ T (n)W(n) Obtain the performance function: J = E{e 2 (n)} Derivation: J = E{d 2 (n) - 2d T (n)X′ T (n)W + W T X′(n)X′ T (n)W} According to the derivation process of the standard LMS algorithm, a similar result can also be obtained, that is, the optimal weight vector is: W * = [E{X′(n)X′ T (n)}] -1 E{X′(n)d(n)} Weight vector update formula: W(n + 1) = W(n) + 2μX′(n)e(n) Then the x-LMS algorithm of the entire filter is summarized as follows: e(n) = d(n) - S T Y(n) W(n + 1) = W(n) + 2μX′(n)e(n) X′(n) = [x′(n), x′(n),..., x′(n - L + 1)] T

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