Dynamic vibration absorption system based on signal monitoring self-closed loop and design method thereof

Abstract

The invention provides a dynamic vibration absorber based on a signal monitoring self-closed loop and a control method of the dynamic vibration absorber based on the signal monitoring self-closed loop, through the dynamic vibration absorber based on the signal monitoring self-closed loop, a frequency collection chip is used for collecting a vibration signal of power equipment and judging whether the vibration absorption frequency meets the requirement or not; under the condition that the requirement is not met, the motion control instruction is sent to the stepping electrode, the stepping motor is controlled to move to the preset position, the vibration absorption frequency of the automatic closed-loop dynamic vibration absorber based on signal monitoring meets the requirement, the precise vibration absorption effect can be achieved, and the service life of transformer equipment is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical vibration control, and specifically relates to a signal monitoring-based automatic closed-loop dynamic vibration absorber and its control method. Background Technique

[0002] Mechanical vibration is likely to cause a reduction in the performance and reliability of the machine or the main structure itself, or affect the performance and reliability of the equipment with the main structure as the platform. Therefore, most of the above-mentioned mechanical vibrations need to be eliminated or suppressed. Among many vibration reduction methods, the dynamic vibration absorber has the characteristics of low cost and good effect, so it has been widely studied and applied. The basic working principle of the dynamic vibration absorber is to attach a sub-oscillation system with mass, damping, and stiffness, that is, the vibration absorber, to a specific part of the controlled main vibration system. By reasonably selecting the relevant parameters of the vibration absorber, the vibration condition of the main system is changed, and the vibration energy is transferred to the vibration absorber, so that the vibration of the main system is reduced.

[0003] However, in the actual application process, once the structure of the traditional dynamic vibration absorber is designed and processed, its characteristic parameters are difficult to adjust in real time. If the vibration frequency of the main system changes due to environmental changes or loosening of its own structure, the dynamic vibration absorber will not be able to obtain an ideal vibration reduction effect in time. The vibration noise of the main system will also affect its service life and cause noise pollution to the surrounding environment. Summary of the Invention

[0004] The present invention proposes a signal monitoring-based automatic closed-loop dynamic vibration absorber and its control method. By detecting the vibration natural frequency of the vibration absorber and the spectral distribution of the vibration source on the surface of the structure, a stepping motor is used as the mass block and its position can be changed, thereby changing the natural frequency of the vibration absorber. An efficient control system is constructed to make the frequencies of multiple oscillators match the frequency of the main vibration system precisely, so as to achieve efficient control of the noise radiation of power equipment.

[0005] The present invention is realized through the following technical solutions:

[0006] A signal monitoring-based automatic closed-loop dynamic vibration absorber, comprising:

[0007] The vibration absorber fixed base is composed of a bracket, a magnet, and an eccentric glass steel plate. The main vibration system and the bracket are connected by a magnet, and the eccentric glass steel plate is fixed to the bracket with bolts;

[0008] The vibration absorber stepping motor assembly is composed of a stepping motor bracket, a connecting plate, an L-shaped connector, a stepping motor, a slide rail, a coupling, and a T-shaped lead screw. The L-shaped connector and the slide rail are fixed on the eccentric glass steel plate with bolts. The stepping motor bracket, the connecting plate and the stepping motor are assembled together, and are connected to the slide rail through the chute at the bottom of the connecting plate. The T-shaped lead screw passes through the L-shaped connector and is connected to the stepping motor through a coupling.

[0009] Specifically, the position where the eccentric glass steel plate is fixed is divided into a first part and a second part. Among them, the lengths of the first part and the second part are different, and the fixed position is the connection between the bolt and the bracket.

[0010] Specifically, the stepping motor guides itself to slide bidirectionally on the slide rail through forward and reverse movements, so as to control the frequency accuracy of vibration absorption within 1 hertz.

[0011] Specifically, the stepping motor includes a first stepping motor and a second stepping motor. The first stepping motor is arranged on the first part, and the second stepping motor is arranged on the second part.

[0012] Furthermore, the signal monitoring-based automatic closed-loop dynamic vibration absorber is designed based on the natural frequency of the vibration absorber structure model. The vibration absorber structure model is established using the finite element method. In the vibration absorber structure model, beam elements are used to simulate the eccentric glass steel plate, point masses are used to simulate the stepping motor, and fixed constraints are used to simulate the constraints of the vibrating surface on the eccentric glass steel plate. For the calculation of the natural frequency of the beam element under load, it is calculated using the finite element method and the bending free vibration differential equation. The bending free vibration differential equation is as follows: In the formula: ρ is the density of the beam material; m j is the mass of the j-th unit length of the beam; E is the elastic modulus of the material; I is the centroidal principal moment of inertia of the cross-section of the beam; x j is the coordinate of the j-th concentrated mass; δ is the δ function; y = y(x, t) is the lateral displacement of the beam.

[0013] A control method includes the following steps:

[0014] Collect the vibration signal of the power equipment using a frequency acquisition chip;

[0015] Determine whether the vibration absorption frequency of the signal monitoring-based automatic closed-loop dynamic vibration absorber meets the requirements based on the collected vibration signal. The signal monitoring-based automatic closed-loop dynamic vibration absorber is arranged on the power equipment;

[0016] In the case of not meeting the requirements, send a motion control instruction to the stepping electrode to control the movement of the two motors to a preset position, so that the vibration absorption frequency of the signal monitoring-based automatic closed-loop dynamic vibration absorber meets the requirements.

[0017] Specifically, the control method further includes: outputting a user interface, where the user interface can be used to select a serial port connection operation, select a target motor, perform target motor control, and perform corresponding frequency acquisition and display of the signal monitoring-based automatic closed-loop dynamic vibration absorber.

[0018] Specifically, the control method further includes the design of a closed-loop automatic control algorithm that adapts to changes in the vibration absorption frequency. In the control algorithm, the frequency is automatically uploaded, the main control circuit automatically analyzes and compares, the main control circuit sends motor control instructions, and the motor drive receives and executes corresponding operations, including the following steps:

[0019] A motor drive board is composed of a single-chip microcomputer chip, a frequency acquisition chip, and an RS485 communication chip. The frequency acquisition chip is used to collect vibration signals, and the collected vibration signals are sent to the single-chip microcomputer chip on the drive board through the IIC bus for data conversion. The converted data is uploaded to the single-chip microcomputer of the main control board through the RS485 communication chip;

[0020] The single-chip microcomputer of the main control board uses an automatic closed-loop control algorithm program to judge whether the frequency meets the vibration absorption requirements according to the uploaded data. When the vibration absorption requirements are met, the main control board has no instruction, and the stepping motor remains stationary, and the vibration absorber works in the best vibration absorption state;

[0021] When the requirements are not met, the main control board issues control instructions to the motor drive boards on both sides according to the high or low frequency, drives the stepping motors on both sides to move to the preset positions, and works together to make the vibration absorption frequency of the vibration absorber meet the requirements.

[0022] Specifically, in the control method, the circuit of the dynamic vibration absorption control system is designed around the main control chip as the main control circuit. The main control circuit has signal transmission and power isolation functions. The motor drive circuit is designed around the single-chip microcomputer chip on the motor drive board, and a motor drive chip is used to control the forward and reverse movement of the stepping motor.

[0023] Specifically, in the design of the control system circuit based on the unique drive mode of the stepping motor, the stepping motor requires a special duty cycle method. By energizing one or more phases of the stator, the current flowing through the coil generates a magnetic field, and the rotor aligns with the magnetic field to achieve the conversion of electrical energy to kinetic energy. In actual use of the stepping motor driver, we often use the subdivision fraction to control the size of the microstep drive. The subdivision technology of the stepping motor is essentially an electronic damping technology. Its main purpose is to weaken or eliminate the low-frequency vibration of the stepping motor. Improving the running accuracy of the motor is only an incidental function of the subdivision technology. Subdivision means that the stepping motor driver divides each pulse sent by the upper-level device into a coefficient of pulses according to the subdivision coefficient set by the stepping motor driver. The actual step angle during the operation of the motor after subdivision is a fraction of the basic step angle.

[0024] Specifically, in the design of the closed-loop automatic control algorithm for adaptive vibration absorption frequency change, the control algorithm realizes the automatic upload of the acquisition frequency, the automatic analysis and comparison by the main control circuit, the main control circuit sending motor control instructions, and controlling the stepping motor to perform structural adjustment. As a simple and practical control method, PID control has been widely used in the drive of stepping motors. It forms a control deviation e(t) based on the input value r(t) and the actual output value c(t), and forms a control quantity by linearly combining the proportional, integral, and differential of the deviation to control the controlled object. According to the mathematical model of the stepping motor, with the frequencies of the structural vibration and the motor drive board vibration as the input quantities and the position of the motor mass block as the output quantity, a PID control system for the stepping motor is designed. The output signal is detected, converted, and compared through the feedback channel, and the control quantity is obtained by using the PID control algorithm, so as to control the movement of the motor mass block to the specified position. The use of a PID controller has the advantages of simple structure, strong robustness, and high reliability. Combining the closed-loop feedback control and the PID control system to detect the position and speed of the rotor, and automatically sending out a drive pulse train according to the optimized lifting and lowering operation curve, improves the torque characteristics of the motor, and at the same time enables the motor to obtain a more accurate, higher, and smoother rotational speed.

[0025] The present invention constructs a software operation platform for the upper computer. The upper computer software has functions such as serial port scanning, communication, multi-channel, precise parameter adjustment, vibration frequency acquisition and display, and vibration frequency effect acquisition and display after vibration absorption. The Fourier transform is used to perform spectral analysis on the collected data, extract the characteristic frequency, and feedback the processing result to the single-chip microcomputer.

[0026] The present invention can achieve efficient vibration absorption with precise identification for different vibration frequencies of different transformer casings. By precisely adjusting the characteristic frequency parameters of the vibration absorber through two modes, the vibration absorption and noise reduction effect is optimized, and the high-efficiency performance of the dynamic vibration absorber for noise reduction is realized.

[0027] The present invention comprehensively uses the serial port, Ethernet, and Internet to obtain the vibration signals of multiple vibration reduction and noise reduction devices themselves and the dynamic vibration absorbers installed thereon, perform spectral analysis, extract characteristic parameters, and then send stepping motor control instructions to precisely adjust the structural parameters of the dynamic vibration absorber to solve the main problem of difficult coordinated control of the vibration absorption frequencies of the multi-dimensional adjustable vibration absorption structure. Description of the Drawings

[0028] Legend:

[0029] Bracket (2.1), magnet (2.2), eccentric fiberglass plate (2.3), stepping motor assembly (2.4);

[0030] Stepper motor bracket (3.1), connecting plate (3.2), L-shaped connector (3.3), stepper motor (3.4), slide rail (3.5), coupling (3.6), T-shaped lead screw (3.7);

[0031] Figure 1 Is the finite element model for calculating the natural frequency of a cantilever beam under load;

[0032] Figure 2 Is the mechanical structure of the present invention;

[0033] Figure 3 Is the structure of the motor assembly;

[0034] Figure 4 Is the schematic diagram of the overall structure of the control system;

[0035] Figure 5 Is the schematic diagram of the RS485 network;

[0036] Figure 6 Is the schematic diagram of the frequency acquisition circuit;

[0037] Figure 7 Is the block diagram of the vibration absorber frequency control system;

[0038] Figure 8 Is the control flow chart of the vibration absorber frequency adjustment function;

[0039] Figure 9 Is the upper computer operation interface. Specific implementation mode

[0040] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0041] Embodiment 1

[0042] A design method of an automatic closed-loop dynamic vibration absorber based on signal monitoring is as follows:

[0043] Step 1: Use the finite element method to establish a vibration absorber structure model, calculate the structural natural frequency, and the model schematic diagram is shown in Figure 1 . Use beam elements to simulate the eccentric glass steel plate, use point masses to simulate the mass blocks, and use fixed constraints to simulate the constraints of the vibration surface on the eccentric glass steel plate. Perform characteristic frequency calculations to obtain the first-order natural frequency. Change the position of the point mass to obtain the transformation curve of the first-order natural frequency with respect to the position of the point mass (hereinafter referred to as the transformation curve). Based on the natural frequency calculation results, perform structural design.

[0044] Specifically, for Figure 1 The finite element model for calculating the natural frequency of a cantilever beam under load, its bending free vibration differential equation is Where ρ is the density of the beam material; m j is the mass of the j-th unit length of the beam; E is the elastic modulus of the material; I is the principal moment of inertia of the centroid of the beam cross-section; x j is the coordinate of the j-th concentrated mass; δ is the δ function; y = y(x, t) is the lateral displacement of the beam; Suppose Substitute into Equation (1) to get Wherein Taking the Laplace transform and then the inverse Laplace transform on both sides of (3), we can obtain Wherein, u(ξ - ξ j ) is the unit step function is the Krylov function, and there is Each Y(ξ j )(j = 1, 2,... n) in Equation (5) is unknown. When ξ = ξ 1 , introduce the operation symbol Then When one end is fixed and the other end is free, according to Y(0) = Y′(0) = 0 and Y(1) = Y′(1) = 0, the frequency equation can be obtained In particular, when there is only one concentrated mass at the free end of the beam, take i = 1, ξ 1 = 1, to get After expansion, we get

[0045] When the mass is at a length of l from the origin, then Substitute into (10) to solve for β; from (4), we can get For the automatic control system, the input quantity is the extracted characteristic frequency, and the output quantity is the rotational speed of the stepping motor. Let the Laplace transform of the input quantity characteristic frequency be R(s), and the Laplace transform of the output quantity rotational speed be N(s); the transfer function of the PID controller is From the closed-loop transfer function formula Substituting into (11), the closed-loop transfer function of the system can be obtained as Where: ζ is the damping ratio ω n Undamped natural oscillation angular frequency K is the proportionality coefficient According to the final value theorem, then When the input is a unit step response, the dynamic performance indexes of the system are Peak time: Overshoot: Settling time (5% error band): Observe the settling time t s (5% error band), σ%, and t p , Φ(s) can be obtained; Also, the length of the mass block from the origin is l, the rotational speed of the motor is N, and the required time Let the starting time be t 0 , then T = t 0 +t 1 Input T into the upper computer,

[0046] Carry out the structural design. In step 1, change the structural parameters such as the thickness, length, and width of the eccentric glass steel plate so that the transformation curve is approximately evenly distributed on both sides of the design frequency. Carry out the detailed structural design:

[0047] Design the fixed base of the vibration absorber, which consists of a bracket 2.1, a magnet 2.2, and an eccentric glass steel plate 2.3. The main vibration system is connected to the bracket through the magnet, and the eccentric glass steel plate is fixed on the bracket by bolts, as Figure 2 shown;

[0048] Design a vibration absorber stepping motor assembly, which consists of a stepping motor bracket 3.1, a connecting plate 3.2, an L-shaped connector 3.3, a stepping motor 3.4, a slide rail 3.5, a coupling 3.6, and a T-shaped lead screw 3.7. The L-shaped connector and the slide rail are fixed on the eccentric fiberglass plate by bolts. The stepping motor bracket, the connecting plate and the stepping motor are assembled together and connected to the slide rail through the chute at the bottom of the connecting plate. The T-shaped lead screw passes through the L-shaped connector and is connected to the stepping motor through a coupling, as Figure 3 shown;

[0049] Assemble each component according to the specified position and sequence, and use a vibration test analyzer to test the natural frequency to verify the rationality of the structural design. Make structural adjustments for unreasonable situations.

[0050] Embodiment 2

[0051] A control method is as follows:

[0052] In step 6, the specific communication circuit functions include building a motor control circuit as Figure 4 shown, and a host computer communication circuit as Figure 5 shown.

[0053] Specifically, the circuit working principle is expressed as: This chip is mounted on the STC15W408AS single-chip microcomputer through the IIC communication method. There are two signals related to the IIC bus: the serial clock line (SCL) and the serial data acquisition line (SDA). The latter is a bidirectional line for sending data to the interface and receiving data from the interface. Both of these lines are connected to Vdd_IO through the pull-up resistors embedded inside the LIS331HH.

[0054] The host computer sends an acceleration acquisition instruction to the main control board through the network interface. The acceleration acquisition instruction contains two parts: an address code and a command code. The address code indicates which main control board or drive board is used to control the acceleration sensor to collect the acceleration signal. After the main control board obtains the relevant data, it performs spectrum analysis on the data, extracts the characteristic parameters, and then issues a motor control instruction to control the rotation speed, direction and pulse number of the stepping motor, and instructs the motor to reach the specified frequency absorption position.

[0055] Furthermore, each sub-module and the control circuit are powered by different power supplies and connected by wires to realize the control of the template vibration absorber by the host computer interface.

[0056] Specifically, the logic control part of the control system uses a 3.3V power supply, which is sourced from the 5V power supply of the USB. 24V is used to power the stepper motor driver boards of all vibration absorbers. The 5V and 24V inputs are isolated, which ensures that even if components on the stepper motor driver board are damaged due to breakdown, it will not cause damage to the main control board; the 24V is controlled by 4 relays, which divides into 4 paths of 24V power supply, and only 1 relay is conducting at the same time, thus reducing the energy consumption requirements; on the stepper motor driver board, the 24V is converted to 5V through a linear voltage regulator chip, and the 5V is converted to 3.3V. The 5V is used to power the main control chip, motor driver, etc., the 3.3V is used to power the acceleration sensor chip, and the 24V itself is used to power the stepper motor driver chip and the stepper motor brake.

[0057] Specifically, for frequency acquisition, a vibration signal acquisition circuit centered around the LIS331HHTR acceleration sensor needs to be established. The frequency acquisition circuit is as Figure 6 shown.

[0058] Specifically, the above host computer software development platform is built based on Visual Studio, and the development language is C#.

[0059] To meet the requirements of this invention, the host computer software should have functions such as serial port scanning communication, multi-channel, adjustable precision parameters, vibration frequency acquisition and display, and vibration frequency effect acquisition and display after vibration absorption, and use Fourier transform to analyze the spectrum of the collected data, extract the characteristic frequency, and feedback the processing result to the single-chip microcomputer. The block diagram of the vibration absorber frequency control system is as Figure 7 shown, and the control flow chart of the vibration absorber frequency adjustment function is as Figure 8 shown.

[0060] Similarly, the host computer can, through manual control, during the process of fitting the frequency, manually adjust the precision of the motor control parameters on the host computer interface, such as rotation time, rotation speed, forward and reverse, start and stop, etc. to find the corresponding frequency, and feedback the vibration absorption effect through the current vibration parameters. The host computer operation interface is as Figure 9 shown.

[0061] Specifically, the host computer can switch to the automatic control mode. After the startup connection is completed, it automatically collects the frequency parameters on the vibration absorption subsystem, and according to the control algorithm frequency written inside the host computer, it automatically controls the vibration absorption subsystem based on the feedback of the current vibration parameters.

[0062] Specifically, for the PID model of the motor mass block control for the vibration frequency changes of the structural vibration and the motor driver board, the PID algorithm is discretized: Where: T is the sampling period k is the sampling sequence number With this approximate method, two forms of digital PID algorithms can be obtained.

[0063] From the above formula, the expression of the discretized position PID control algorithm can be derived: From the above formula, it can be seen that the output u(k) of digital regulation is related to all past deviation signals, and the computer needs to accumulate e(i). In addition, in motor control, the current loop and speed loop generally use PI control more in the position form. The derivation of the position PI formula can be obtained by superimposing the increments at each moment of the incremental PI algorithm, and the formula of the incremental PI can be obtained by discretizing the transfer function of PI: Backward difference discretization: By iterative accumulation, the position PID formula can be obtained:

[0064] Since the position PID algorithm is not convenient enough, not only does it need to accumulate the deviation, occupying too much storage unit, but it is also not convenient to write programs, so some improvements are needed. Taking the increment of the position form, the incremental PID algorithm can be obtained: u(k) in the formula is the output of the current PID algorithm.

Claims

1. An automatic closed-loop dynamic vibration absorber based on signal monitoring, characterized in that: include: The vibration absorber fixed base 2 is composed of a bracket (2.1), a magnet (2.2), and an eccentric glass fiber reinforced plastic plate (2.3); the power equipment and the bracket (2.1) are connected via the magnet (2.2); and the eccentric glass fiber reinforced plastic plate (2.3) is fixed to the bracket (2.1) via bolts; The vibration absorber stepper motor assembly 3 is composed of a stepper motor bracket (3.1), a connecting plate (3.2), an L-shaped connector (3.3), a stepper motor (3.4), a slide rail (3.5), a coupling (3.6), and a T-shaped lead screw (3.7). The L-shaped connector (3.3) and the slide rail (3.5) are fixed to the eccentric glass fiber reinforced plastic plate (2.3) by bolts. The stepper motor bracket (3.1), the connecting plate (3.2) and the stepper motor (3.4) are assembled together and connected to the slide rail (3.5) through the slide groove at the bottom of the connecting plate (3.2). The T-shaped lead screw (3.7) passes through the L-shaped connector (3.3) and is connected to the output shaft of the stepper motor (3.4) through the coupling (3.6).

2. The automatic closed-loop dynamic vibration absorber based on signal monitoring according to claim 1 is characterized in that: The eccentric glass fiber reinforced plastic plate (2.3) is divided into a first part and a second part by a fixed position, wherein the first part and the second part have different lengths, the fixed position is the connection between the bolt and the bracket (2.1), there are two vibration absorber stepper motor assemblies 3, one of the two vibration absorber stepper motor assemblies 3 is arranged on the first part, and the other of the two vibration absorber stepper motor assemblies 3 is arranged on the second part.

3. The automatic closed-loop dynamic vibration absorber based on signal monitoring according to claim 1 is characterized in that: The stepper motor (3.4) guides itself to slide bidirectionally on the slide rail (3.5) through forward and reverse movements based on the motion control instruction, thereby controlling the frequency accuracy of vibration absorption within a preset hertz.

4. The automatic closed-loop dynamic vibration absorber based on signal monitoring according to claim 1 is characterized in that: The signal monitoring-based automatic closed-loop dynamic vibration absorber is designed based on the natural frequency using the vibration absorber structure model. The vibration absorber structure model is established using the finite element method. In the vibration absorber structure model, beam units are used to simulate the eccentric glass fiber reinforced plastic plate, and point mass is used to simulate the stepper motor. Fixed constraints are used to simulate the constraints of the vibration surface on the eccentric glass fiber reinforced plastic plate. The natural frequency of the beam unit under the load is calculated using the finite element method and the bending free vibration differential equation, wherein the bending free vibration differential equation is: Where: ρ is the density of the beam material; m j is the mass of the jth unit length of the beam; E is the elastic modulus of the material; I is the principal moment of inertia of the cross-section centroid of the beam; x j is the coordinate of the jth concentrated mass; δ is the δ function; y=y(x, t) is the lateral displacement of the beam.

5. A control method, characterized in that: The following steps are involved: Use frequency acquisition chips to collect vibration signals of power equipment; Determine, based on the vibration signal, whether the vibration absorption frequency of the automatic closed-loop dynamic vibration absorber based on signal monitoring according to any one of claims 1 to 4 meets the requirements, wherein the automatic closed-loop dynamic vibration absorber based on signal monitoring is arranged on the power equipment; When the requirements are not met, a motion control instruction is sent to the stepper motor to control the stepper motor to move to a preset position according to the motion control instruction, so that the vibration absorption frequency of the automatic closed-loop dynamic vibration absorber based on signal monitoring meets the requirements.

6. The control method according to claim 1, characterized in that: The method further includes: outputting a user interface, wherein the user interface displays an option for selecting a serial port connection operation, an option for selecting a target motor, an option for controlling the selected target motor, and a vibration absorbing frequency of the signal monitoring automatic closed-loop dynamic vibration absorber; In response to the user's operation information on the option of the serial port connection operation, a serial port connection is performed, or, in response to the user's operation information on the option for selecting a target motor, a target motor is selected, or, in response to the user's operation information on the option of controlling the selected target motor, the target motor is controlled.

Images