阅读说明：本技术 一种机械制冷机自适应高阶振动主动控制方法 (Self-adaptive high-order vibration active control method for mechanical refrigerator ) 是由 杨宝玉 张家昆 倪天智 吴亦农 于 2020-07-01 设计创作，主要内容包括：本发明公开了一种机械制冷机自适应高阶振动主动控制方法,控制方法包括以下步骤：(1)将交流驱动控制信号x(n)输至机械制冷机内,驱动直线电机；(2)将交流驱动控制信号x(n),作为参考信号和采集到的振动信号e(n),一起输入自适应高阶振动主动控制器,生成减振器驱动控制信号y(n)；(3)将生成的减振器驱动控制信号y(n),输入减振器,驱动减振器输出减振力y′(n),抵消制冷机本身产生的振动力d(n),并采集更新振动信号e(n)；(4)将采集更新后的振动信号e(n),与交流驱动控制信号x(n)重新一起输入至自适应高阶振动主动控制器中,生成新的y(n)返回步骤(3)。步骤(3)与步骤(4)之间来回迭代,使得e(n)的均方差最小。实测证明,本方法在对机械制冷机高阶振动进行主动控制时,能实现各阶次快速地、有效地收敛抑制。(The invention discloses a self-adaptive high-order vibration active control method for a mechanical refrigerator, which comprises the following steps: (1) inputting an alternating current driving control signal x (n) into the mechanical refrigerator to drive the linear motor; (2) inputting an alternating current drive control signal x (n) serving as a reference signal and an acquired vibration signal e (n) into a self-adaptive high-order vibration active controller together to generate a vibration damper drive control signal y (n); (3) inputting the generated vibration damper driving control signal y (n) into the vibration damper, driving the vibration damper to output a vibration reduction force y' (n), offsetting a vibration force d (n) generated by the refrigerator, and collecting an updated vibration signal e (n); (4) and (3) inputting the collected and updated vibration signal e (n) and the alternating current driving control signal x (n) into the self-adaptive high-order vibration active controller again, and generating new y (n) and returning to the step (3). And (4) iterating back and forth between the step (3) and the step (4) to minimize the mean square error of e (n). The actual measurement proves that the method can realize rapid and effective convergence suppression of each order when the high-order vibration of the mechanical refrigerator is actively controlled.)

1. A self-adaptive high-order vibration active control method for a mechanical refrigerator is characterized by comprising the following steps:

(1) inputting an alternating current driving control signal x (n) into the mechanical refrigerator to drive the two opposite linear motors;

(2) inputting an alternating current driving control signal x (n) as a reference signal and an acquired vibration signal e (n) into a self-adaptive high-order vibration active controller together to generate a vibration damper driving control signal y (n);

(3) inputting the generated vibration damper driving control signal y (n) into a vibration damper installed in the refrigerator, driving the vibration damper to output a vibration damping force y' (n), offsetting a vibration force d (n) generated by the refrigerator, and collecting an updated vibration signal e (n);

(4) and (3) inputting the collected and updated vibration signal e (n) and the alternating current driving control signal x (n) into the self-adaptive high-order vibration active controller again, and generating new y (n) and inputting the new y (n) back to the step (3). And (4) iterating back and forth between the step (3) and the step (4) to enable the mean square deviation value of e (n) to be minimum.

2. The adaptive high-order vibration active control method for the mechanical refrigerator according to claim 1, wherein the method comprises the following steps:

in the step (2), the adaptive high-order vibration active controller is formed by connecting adaptive filters with different order frequencies in parallel, and the adaptive filters comprise two parts, namely filters and an adaptive algorithm; the adaptive filter carries out N frequency multiplication processing on a reference input signal x (N) to obtain x_N(N) simultaneously separating the vibration signal e with the frequency of the order N from the vibration signal e (N) by a digital band-pass filter_N(n); will signal x_N(n) and signal e_N(N) input into a single adaptive filter to generate a damper drive control signal y for vibrations of the N-order frequency_N(n)；

In order to realize the active control of the vibration of K different-order frequency points, the outputs of K adaptive filters are accumulated in parallel, and a vibration damper driving control signal y (n) can be obtained:

the filter is a second-order transverse finite impulse response filter and is used for multiplying an input N frequency signal x_N(n) Hilbert transform to obtain x_1N(n) of (a). Will signal x_N(n) and the signal x_1N(N) forming N multiplied signal vectorsInput second order transverse finite impulse response filter, and weight coefficient vector of filter

For input N frequency multiplication signal vectorThe signal vector obtained by phase compensation

The technical field is as follows:

the invention relates to a self-adaptive high-order active vibration control method for a mechanical refrigerator, which is suitable for scenes which need to provide a low-temperature environment by applying the mechanical refrigerator and have high requirements on vibration, such as precision optical loads and the like. The invention can quickly and adaptively reduce the vibration interference of multi-order frequency, improve the stability of the refrigerating machine and has important significance in the scenes of aerospace precision optical loads and the like.

Background art:

the mechanical refrigerator has the advantages of large refrigerating capacity, low refrigerating temperature, high efficiency, small volume and light weight, and meets the temperature required by normal work of an infrared detector, superconducting filtering and the like. With the successful development of the Oxford Stirling refrigerating machine at the end of the last 80 years, the service life and the reliability of the mechanical refrigerating machine are greatly improved, so that the mechanical refrigerating machine is widely applied to the fields of infrared photoelectric systems, superconducting quantum interference, low-temperature superconducting filtering and the like.

However, the vibration generated by the mechanical refrigerator is a key factor affecting the application thereof. The refrigerator for photoelectric detection, superconducting filtering and superconducting quantum interference is mainly of a split type dual-drive structure and comprises a compressor and a cold finger, a moving part reciprocates along the axial direction at a certain frequency, and a shell and a support generate corresponding reaction force so as to cause vibration of the refrigerator. A large number of experimental analyses find that the vibration of the refrigerating machine mainly consists of fundamental frequency and a series of harmonic components, wherein the fundamental frequency is the driving frequency of the linear motor and is generally a fixed value within 40-120Hz, and the harmonic components are derived from nonlinear factors of the driving force, the spring and the damping part. The vibration of the mechanical refrigerator produces great harm to the instrument; the vibration can drive a detection device connected with the cold finger to reciprocate, so that the detection device deviates from the normal 'focal depth' range of an optical system of the instrument, imaging is blurred, and the resolution and the positioning accuracy of a detection target are reduced; vibrations can cause electromagnetic interference signals and even mechanical resonance of the instrument, causing large interference to some sensitive sensors.

The invention content is as follows:

1. objects of the invention

The invention aims to design a set of self-adaptive active vibration control system by combining the practical condition of a refrigerator and the basic principle of vibration control aiming at the problems of the high-order vibration reduction technology of the existing mechanical refrigerator, can quickly and accurately complete iteration through a self-adaptive algorithm, and can complete active suppression of multi-order frequency vibration.

2. Technical scheme

A self-adaptive high-order active vibration control method for a mechanical refrigerator is characterized by comprising the following steps:

comprises the following steps:

(1) and (3) transmitting the alternating current driving control signal x (n) to a mechanical refrigerator to drive the two opposite linear motors.

(2) And inputting the alternating current driving control signal x (n) as a reference signal and the acquired vibration signal e (n) into an adaptive high-order vibration active controller together to generate a vibration damper driving control signal y (n).

(3) And inputting the generated vibration damper driving signal y (n) into a vibration damper installed in the refrigerator, driving the vibration damper to output a vibration damping force y' (n), offsetting a vibration force d (n) generated by the refrigerator, and collecting and updating a vibration signal e (n).

(4) And (3) inputting the collected and updated vibration signal e (n) and the single-frequency alternating current driving signal x (n) into the self-adaptive high-order vibration active controller again, and generating new y (n) to the step (3). And (4) iterating back and forth between the step (3) and the step (4) to enable the mean square deviation value of e (n) to be minimum.

In step (2), the high-order vibration controller is formed by connecting adaptive notch filters with different order frequencies in parallel. The adaptive filter composition comprises two parts of a filter and an adaptive algorithm. N frequency multiplication processing is carried out on a reference input signal x (N) to obtain an N frequency multiplication input signal x_N(n); meanwhile, the corresponding vibration frequency of the order N in the error signal e (N) is separated by a digital band-pass filter to obtain the vibration e of the frequency point of the order N_N(n) of (a). N frequency multiplication input signal x_N(N) and the vibration e (N) of the N-order frequency point after vibration reduction are input into a single adaptive filter, and vibration reduction driving output y aiming at the vibration of the N-order frequency can be obtained_N(n). If the vibration of K different order frequency points is to be suppressed, then the outputs of K parallel adaptive filters are accumulated to obtain a high-order vibration reduction output y (n).

Considering a single order frequency filter, the adaptive filter comprises two parts, namely a filter and an adaptive algorithm.

Wherein the filter is characterized by:

the filter structure is selected to be a transverse Finite Impulse Response (FIR) filter based in part on adaptive process stability considerations. Defining the input signal vector and the filter weight coefficient vector at n time as:

the filter output can be expressed as the input signal and the FIR filter coefficients w_l(n) convolution of:

in combination with the objective function d (n), the filter output error can be calculated as:

consider the vibration signal of a mechanical refrigerator as a series of discrete harmonics, i.e., narrowband signals. Therefore, the signal of the single-order frequency point can be constructed by using a filter with L being 2, and the filter output is simplified as follows:

y(n)＝w₁(n)x(n)+w₂(n)x(n-1)

considering an omega-order single-frequency point vibration as a cosine waveform with a specific amplitude and phase, the vibration can be decomposed into the form of adding two trigonometric functions:

setting:

x_0Ω(n)＝cos(Ωn)

x_1Ω(n)＝sin(Ωn)

so that the output signal y of a single frequency point of the order of Ω_ΩThe relation (n) can be expressed as

Considering the input reference signal x in combination with the vibration system characteristics_N(n) may be expressed as a cosine signal set to x_0N(n) of (a). By Hilbert transform, x_0N(n) enabling a 90 ° phase shift to x_1N(n) and can thus be used to complete the construction of the output adaptive filter output. Output y of order N single frequency for time N_N(n) to obtain:

for an adaptive algorithm in a constituent adaptive filter, characterized by:

the adaptive algorithm corrects the transfer function of the system by automatically updating the filter coefficient, so as to generate a vibration reduction mechanical signal which is equal to the vibration amplitude of the targeted order single frequency and has opposite phase. The adaptive algorithm is implemented using a stochastic gradient-based, model-independent Least Mean Square (LMS) algorithm. In conjunction with the filter structure, the simplified N-order filter weight coefficient vector is represented as:

by an iterative relationship:

performing an iterative update of the weight coefficients, wherein e_N(N) measuring and collecting vibration signals of the N-order frequency points; μ is a step size factor, which will generally take a relatively small value;for a single frequency input signal vectorObtained through phase compensation.

3. Advantageous effects

(1) The invention provides a self-adaptive high-order active vibration control method for a mechanical refrigerator. Compared with the traditional active control method, the method gets rid of the restriction of the influence of the transfer function error of the vibration reducer, can eliminate multi-order noise simultaneously, and has better stability, convergence and robustness. The convergence time of the control algorithm is also shorter.

(2) The idea presented herein for adaptive high-order vibration active control methods has wide application space. The vibration-damping and noise-eliminating device can be applied to active vibration reduction of mechanical refrigerators such as Stirling refrigerators, pulse tubes and the like, and can solve the problems of vibration reduction and noise elimination of motors, vehicles, air conditioners, pipelines and the like with similar vibration and noise characteristics.

Description of the drawings:

fig. 1 is a schematic diagram of a technical scheme of a refrigerator adaptive high-order vibration active control method.

FIG. 2 is a diagram of the vibration test results of a refrigerator without adaptive high-order vibration active control.

FIG. 3 is a diagram of the vibration test results of a refrigerator during adaptive high-order vibration active control.

The specific implementation mode is as follows:

the following further describes the embodiments of the present invention with reference to the drawings, but the embodiments of the present invention are not limited thereto. The spirit, features, modes and functions of the present invention are all within the scope of the present invention.

Referring to fig. 1, the invention is realized by the following technical scheme: a self-adaptive high-order active vibration control method for a mechanical refrigerator comprises the following steps:

(1) and outputting the driving control signals x (n) to two opposite linear motors in the mechanical refrigerator.

(2) x (n) is used as a reference signal, an initial vibration signal e (n) is collected and input into a controller integrated with a self-adaptive high-order vibration active control algorithm, and a vibration damper driving control signal y (n) is generated.

(3) The vibration damper driving control signal y (n) drives the vibration damper, outputs vibration d (n) generated by cancellation of the damping force y' (n), and collects and updates the vibration signal e (n).

(4) And (3) feeding the updated e (n) and x (n) back to the adaptive high-order vibration controller, realizing the iteration of the adaptive algorithm in the controller, generating a new vibration reduction driving signal y (n), repeating the step (3), and iterating back and forth between the step (3) and the step (4) to finally enable the e (n) to present the minimum mean square error.

As shown in fig. 2 and fig. 3, it is proved that the method can realize rapid and effective convergence suppression of each order when the method is used for active control of high-order vibration of the mechanical refrigerator.