A new micro-nano displacement self-feedback method of high dynamic voice coil motor

Abstract

This invention discloses a novel micro-nano displacement self-feedback method for a high-dynamic voice coil motor, comprising: injecting a high-frequency signal isolated from the drive signal in the frequency domain into the drive signal of the voice coil motor; inductively modulating the high-frequency signal with the drive signal to form a high-frequency detection signal; extracting the high-frequency component of the modulated high-frequency detection signal in real time based on the functional relationship between the micro-displacement of the voice coil motor and the change in inductance; and performing micro-displacement demodulation, nonlinear compensation, and correction on the high-frequency component to obtain the micro-displacement feedback amount of the voice coil motor. This invention can achieve the motion function of a high-dynamic voice coil motor while enabling the voice coil motor to have a high-resolution micro-displacement self-feedback function without adding hardware sensors, thereby reducing the cost of the entire voice coil motor system and making the structure more compact and reliable.

Description

Technical Field

[0001] This invention belongs to the field of voice coil motor displacement resolution control and positioning technology, specifically relating to a novel micro-nano displacement self-feedback method for high dynamic voice coil motors. Background Technology

[0002] Voice coil motors (VCOs) are direct-drive motors that avoid transmission backlash in the drive system. They offer advantages such as infinite resolution, zero hysteresis, low inertia of moving parts, high-frequency response, small size, and high controllability. VCO ultra-precision control and positioning technology is widely used in lithography machine stages, scanning tunneling microscopes, nanoscale system packaging, cell manipulation, ultra-precision optical device fabrication, and precision optical fast-reflection mirror control.

[0003] In these precision electromechanical systems, achieving nanometer-level displacement resolution control and positioning requires meeting two fundamental conditions: the voice coil motor drive components must meet the accuracy requirements for high-frequency response and nanometer-level precision displacement feed control; and a nanometer-level displacement sensor must be installed to provide real-time position or velocity information. Because the inertia of the moving parts of the voice coil motor is extremely small, it is highly sensitive to the load of additional measurement sensors. Therefore, non-contact measurement is predominantly used for voice coil motor micro-displacement sensors. Commonly used sensors include eddy current sensors, CCD optical sensors, and laser interferometers. These sensors are typically much larger than the voice coil motor itself, making installation impossible in compact system structures. This often presents a dilemma: installing sensors results in an excessively large structure, while not using sensors prevents open-loop control from achieving the required accuracy.

[0004] How to provide a solution that enables high-dynamic voice coil motor motion without adding hardware sensors, while also giving the voice coil motor high-resolution micro-displacement self-feedback functionality, is an urgent problem to be solved. Summary of the Invention

[0005] The main objective of this invention is to provide a novel micro-nano displacement self-feedback method for high dynamic voice coil motors, thereby overcoming the shortcomings of existing technologies.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: a novel micro-nano displacement self-feedback method for a high-dynamic voice coil motor, comprising: injecting a high-frequency signal isolated from the frequency domain of the driving signal into the driving signal of the voice coil motor; inductively modulating the high-frequency signal with the driving signal to form a high-frequency detection signal; extracting the high-frequency component of the modulated high-frequency detection signal in real time based on the functional relationship between the micro-displacement of the voice coil motor and the change in inductance; and performing micro-displacement demodulation, nonlinear compensation, and correction on the high-frequency component to obtain the micro-displacement feedback amount of the voice coil motor.

[0007] In a preferred embodiment, the process of inductively modulating the high-frequency signal and the drive signal includes: amplifying the audio power of the high-frequency signal and the drive signal, outputting the amplified drive signal through the voice coil vibration system of the voice coil motor and inductively modulating it with the amplified high-frequency signal to form a high-frequency detection signal.

[0008] In a preferred embodiment, the process of inductor modulation of the high-frequency signal and the driving signal further includes: filtering the high-frequency detection signal through a bandpass filter to output the filtered high-frequency detection signal.

[0009] In a preferred embodiment, the process of performing micro-displacement demodulation on the high-frequency component includes: performing orthogonal demodulation on the filtered high-frequency detection signal to obtain the instantaneous phase of the high-frequency detection signal, and establishing a correlation model between the instantaneous displacement of the voice coil and the instantaneous phase.

[0010] In a preferred embodiment, the process of performing quadrature demodulation on the filtered high-frequency detection signal includes:

[0011] Let the expression for the high-frequency detection signal M(t) be M(t)=Asin(ωt+φ(t)), where ω is its angular frequency and φ is a known quantity;

[0012] Orthogonal decomposition of signal quantity U R U q Multiply the reference signals -sin(ωt) and cos(ωt) by M(t) respectively, i.e.:

[0013]

[0014]

[0015] Applying low-pass filtering to Equations 1 and 2, and extracting the low-frequency component from the high-frequency detection signal, yields:

[0016]

[0017] According to Formula 3, the arctangent function tag is used. -1 The instantaneous phase φ(t) is obtained.

[0018] In a preferred embodiment, the process of establishing the correlation model between the instantaneous displacement and the instantaneous phase of the voice coil includes: first obtaining the functional relationship between the change in inductance and the instantaneous phase, and then obtaining the functional relationship between the micro-displacement of the voice coil and the change in inductance.

[0019] In a preferred embodiment, the functional relationship between the change in inductance and the instantaneous phase is as follows:

[0020]

[0021] Among them, R m R is the sampling resistor. o Let ω be the pure resistance of the voice coil motor, ω be the carrier frequency, and L be the coil inductance. Let d be the carrier phase angle and d be the differential operator.

[0022] In a preferred embodiment, the functional relationship between the micro-displacement of the voice coil and the change in inductance is as follows:

[0023]

[0024] Where L0 is the change in inductance when the displacement y = 0, Rm is the sampling resistor, Ro is the sampling pure resistance value of the voice coil motor, f(y) is the functional relationship between the change in inductance and the vibration displacement y, i.e. dL = f(y), and f′(0) is the term linear factor constant of the Taylor expansion of f(y).

[0025] In a preferred embodiment, the process of nonlinear compensation and correction of the high-frequency components includes: using a detection instrument in an offline state to correct the correlation function between the micro-displacement of the voice coil and the change in inductance, thereby further performing nonlinear compensation and correction.

[0026] Compared with the prior art, the beneficial effects of the present invention are at least as follows:

[0027] This invention, without displacement sensors, employs a frequency domain isolation method to inject high-frequency signals into the voice coil motor drive signal. Through real-time demodulation of the injected high-frequency information components and online nonlinear compensation and correction, high-resolution real-time feedback of the voice coil motor's micro-displacement is obtained. This invention enables high-dynamic voice coil motor motion functionality without adding hardware sensors, while simultaneously providing high-resolution micro-displacement self-feedback capabilities. This reduces the overall cost of the voice coil motor system and results in a more compact and reliable structure. It can meet the application requirements of direct closed-loop control of voice coil motors in situations where hardware sensor installation is inconvenient due to compact design, such as fast laser corner reflectors and fast-reflecting mirrors for guide heads, and has strong market potential. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1This is a schematic diagram illustrating the principle of the micro-nano displacement self-feedback method for the voice coil motor of the present invention;

[0030] Figure 2 This is a schematic diagram illustrating the frequency domain isolation between the high-frequency signal injected in this invention and the effective bandwidth of the voice coil vibration system;

[0031] Figure 3 This is a schematic diagram illustrating the principle of micro-displacement demodulation of high-frequency signals according to the present invention;

[0032] Figure 4 This is a schematic diagram of the orthogonal decomposition principle of the present invention. Detailed Implementation

[0033] The invention will be more fully understood through the following detailed description, which should be read in conjunction with the accompanying drawings. Detailed embodiments of the invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, the specific functional details disclosed herein should not be construed as limiting, but rather as the basis for the claims and as intended to teach those skilled in the art to employ the representative basis of the invention in different ways in any suitable detailed embodiment.

[0034] The present invention discloses a novel micro-nano displacement self-feedback method for a high dynamic voice coil motor. In the absence of a displacement sensor, a frequency domain isolation method is used to inject a high-frequency signal into the voice coil motor drive signal. By real-time demodulation of the high-frequency injected information component and online nonlinear compensation and correction, a high-resolution real-time feedback quantity of the micro-displacement of the voice coil motor is obtained.

[0035] The basic design principle of this invention is as follows: When the voice coil vibration system generates a micro-displacement x, and the coil position changes, its coil inductance L changes simultaneously. Based on this physical phenomenon, by studying the coupling law of force, magnetism, and electricity between the driving current and the electromagnetic field of the voice coil vibration system, the winding coil structure and magnetic circuit structure of the voice coil vibration system are optimized. While achieving the function of a high-dynamic voice coil vibration system, a linear functional relationship is established between the change in coil inductance and the change in the driving displacement of the voice coil vibration system at a specific high frequency. This high-frequency signal is injected into the driving signal of the voice coil vibration system, and the two are isolated in the frequency domain. When the voice coil is actuated by a micro-displacement, the coil inductance changes. By analyzing the close intrinsic relationship between the inductance modulation effect of the high-frequency current signal and the dynamic position of the voice coil, the change in the dynamic position of the voice coil is indirectly obtained, thereby realizing sensorless dynamic detection of the voice coil modulation displacement.

[0036] Specifically, such as Figure 1As shown in this embodiment, the novel micro-nano displacement self-feedback method for a high dynamic voice coil motor includes: injecting a high-frequency signal isolated from the frequency domain of the driving signal into the driving signal of the voice coil motor; inductively modulating the high-frequency signal with the driving signal to form a high-frequency detection signal; extracting the high-frequency component of the modulated high-frequency detection signal in real time based on the functional relationship between the micro-displacement of the voice coil motor and the change in inductance; and performing micro-displacement demodulation, nonlinear compensation, and correction on the high-frequency component to obtain the micro-displacement feedback amount of the voice coil motor.

[0037] Among them, the driving signal of the voice coil motor is a limited bandwidth signal (limited by the frequency response bandwidth of the mechanical system of the voice coil vibration system), and the frequency of the superimposed high-frequency signal can be isolated from the driving signal so that they do not interfere with each other. Figure 2 A schematic diagram illustrating the frequency domain isolation between the injected high-frequency signal and the effective bandwidth of the voice coil vibration system.

[0038] Combination Figure 1 and Figure 3 As shown, the process of inductive modulation of the high-frequency signal and the driving signal specifically includes: amplifying the audio power of the high-frequency signal H(t) and the driving signal S(t); outputting the amplified driving signal S(t) as y(t) through the voice coil vibration system of the voice coil motor, and then inductively modulating it with the amplified high-frequency signal H(t) to obtain the high-frequency detection signal {H(t), y(t)}. This high-frequency detection signal is then filtered through a bandpass filter to output the filtered high-frequency detection signal M(t).

[0039] The process of micro-displacement demodulation of high-frequency components includes: performing orthogonal demodulation on the filtered high-frequency detection signal to obtain the instantaneous phase of the high-frequency detection signal, and establishing a correlation model between the instantaneous displacement of the voice coil and the instantaneous phase.

[0040] First, the modulated high-frequency detection signal M(t) is orthogonally decomposed to obtain its instantaneous phase φ(t). Specifically, the orthogonal decomposition principle is as follows:

[0041] Let the expression for the high-frequency detection signal M(t) be: M(t) = Asin(ωt + φ(t), where ω is its angular frequency and φ(t) is a known quantity. Multiplying the reference signals -sin(ωt) and cos(ωt) by the high-frequency detection signal M(t) respectively, we get:

[0042]

[0043]

[0044] Applying low-pass filtering to Formulas 1 and 2 removes high-frequency components and retains the low-frequency components, we obtain:

[0045]

[0046] According to Formula 3, through the arctangent function tag -1 The instantaneous phase φ(t) can be obtained.

[0047] Next, a correlation model is established between the instantaneous displacement y(t) of the voice coil and the instantaneous phase φ(t). This process specifically includes: first, obtaining the functional relationship between the change in inductance and the instantaneous phase, and then obtaining the functional relationship between the micro-displacement of the voice coil and the change in inductance.

[0048] like Figure 4 As shown, let the series sampling resistance be Rm, the complex impedance of the vibration coil be Z = jL + R0, and the excitation voltage be U(t). According to the principle of linear voltage divider, the voltage output formula at the sampling terminal is:

[0049]

[0050] When the coil inductance L changes, the corresponding instantaneous phase angle (t) is:

[0051]

[0052] When the inductance L changes, the phase angle (t) changes accordingly. Differentiating both sides of the above equation, we get:

[0053]

[0054] The above equation reveals the functional relationship between the change in inductance and the change in phase angle.

[0055] Next, we need to understand the functional relationship between the instantaneous displacement y of the voice coil and the change in inductance dL. The instantaneous displacement of the voice coil directly leads to a change in inductance, and their relationship can be expressed as a function f(y) passing through the origin (0, 0), i.e.:

[0056] dL=f(y) Formula 7;

[0057] Since the instantaneous displacement y of the voice coil is in a state of slight vibration, it can be expanded in Taylor series at y=0, yielding:

[0058]

[0059] For example, when using a first-order approximation, The functional relationship between y and y can be approximated as:

[0060]

[0061] In Formula 9, L0 is the inductance value when y = 0, which can be directly measured by an instrument when the voice coil is stationary. Rm is the sampling resistor, and Ro is the pure sampling resistance value of the voice coil armature, which can be measured by an instrument. f′(0) is the linearity factor constant, which can be obtained by offline calibration of the linear relationship between the instantaneous displacement y of the voice coil and the change in inductance dL of the voice coil.

[0062] Based on the above signal detection and processing flow, the voice coil vibration displacement is directly proportional to the phase change of the injected signal, that is: This requires that the change in armature inductance of the voice coil vibration system be proportional to its vibration displacement, i.e., y∝ΔL. This is also the goal of this invention to optimize the voice coil motor vibration system.

[0063] In addition, to improve the accuracy of instantaneous displacement detection of the voice coil motor, high-precision detection instruments (such as laser rangefinders) can be used offline to correct the correlation function between the micro-displacement of the voice coil and the change in inductance, and to optimize the dynamic observer algorithm.

[0064] In terms of hardware circuitry, the main processor adopts an FPGA+ARM architecture. The ARM CPU is a high-performance STM32H743 processor with a clock speed of 400MHz. The FPGA is an Altera EP4CE115F23I7N, a field-programmable gate array (FPGA-Cyclone IV E 7155 LABs 280 IOs), with a maximum operating frequency of 200MHz. It has 7155 logic array blocks, 280 IOs, BGA packaging, and a total memory of 3888kbit. The FPGA+ARM architecture's processing capabilities meet the requirements of multi-channel array data acquisition and front-end data processing. Furthermore, the FPGA+ARM processor serves as the circuit carrier for formulas 1 to 9 of the specific embodiments of this invention.

[0065] The advantages of this invention are at least as follows: In the absence of a displacement sensor, a high-frequency signal is injected into the voice coil motor drive signal using a frequency domain isolation method. Through real-time demodulation of the injected high-frequency information component and online nonlinear compensation and correction, a high-resolution real-time feedback of the voice coil motor's micro-displacement is obtained. This invention can achieve high-dynamic voice coil motor motion functionality while simultaneously enabling the voice coil motor to possess high-resolution micro-displacement self-feedback capabilities without adding hardware sensors. This reduces the overall cost of the voice coil motor system and results in a more compact structure and higher reliability. It can meet the application requirements of direct closed-loop control of voice coil motors in situations where hardware sensor installation is inconvenient due to the compact structure, such as fast laser corner reflectors and fast-reflecting mirrors for guide heads, and has strong market potential.

[0066] All aspects, embodiments, features, and examples of this invention are to be regarded as illustrative in all respects and are not intended to limit the invention, the scope of which is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0067] The use of headings and sections in this invention is not intended to limit the invention; each section can be applied to any aspect, embodiment or feature of the invention.

Claims

1. A novel micro-nano displacement self-feedback method for a high dynamic voice coil motor, characterized in that, The method includes: injecting a high-frequency signal isolated from the frequency domain of the drive signal into the drive signal of the voice coil motor; inductively modulating the high-frequency signal with the drive signal to form a high-frequency detection signal; extracting the high-frequency component of the modulated high-frequency detection signal in real time based on the functional relationship between the micro-displacement of the voice coil motor and the change in inductance; and performing micro-displacement demodulation and nonlinear compensation and correction on the high-frequency component to obtain the micro-displacement feedback of the voice coil motor; the process of inductively modulating the high-frequency signal with the drive signal includes: amplifying the audio power of the high-frequency signal and the drive signal; outputting the amplified drive signal through the voice coil vibration system of the voice coil motor and inductively modulating it with the amplified high-frequency signal to obtain a high-frequency detection signal; the process of inductively modulating the high-frequency signal with the drive signal further includes: filtering the high-frequency detection signal through a bandpass filter to output a filtered high-frequency detection signal; the process of demodulating the micro-displacement of the high-frequency component includes: orthogonally demodulating the filtered high-frequency detection signal to obtain the instantaneous phase of the high-frequency detection signal, and establishing a correlation model between the instantaneous displacement and the instantaneous phase of the voice coil; the process of orthogonally demodulating the filtered high-frequency detection signal includes: Let the expression for the high-frequency detection signal M(t) be: ,in, Let be its angular frequency, and be a known quantity; Orthogonal decomposition of signal quantity U R U q Take reference signals respectively , and Multiplication, that is: Official 1; Official 2; Applying low-pass filtering to Equations 1 and 2, and extracting the low-frequency component from the high-frequency detection signal, yields: , Official 3; According to Formula 3, the arctangent function... The instantaneous phase is obtained .

2. The novel micro-nano displacement self-feedback method for a high dynamic voice coil motor according to claim 1, characterized in that: The process of establishing the correlation model between the instantaneous displacement and instantaneous phase of the voice coil includes: firstly obtaining the functional relationship between the change in inductance and the instantaneous phase, and then obtaining the functional relationship between the micro-displacement of the voice coil and the change in inductance.

3. A novel micro-nano displacement self-feedback method for a high dynamic voice coil motor according to claim 2, characterized in that: The functional relationship between the change in inductance and the instantaneous phase is as follows: ； Among them, R m R is the sampling resistor. o This is the pure resistance value of the voice coil motor. Where L is the carrier frequency and L is the coil inductance. Let d be the carrier phase angle and d be the differential operator.

4. A novel micro-nano displacement self-feedback method for a high dynamic voice coil motor according to claim 2, characterized in that: The functional relationship between the minute displacement of the voice coil and the change in inductance is as follows: ； in, Let Rm be the change in inductance when the displacement y=0, Rm be the sampling resistor, and Ro be the pure resistance value of the voice coil motor. This represents the functional relationship between the change in inductance and the vibration displacement y, i.e. , for The linear factor constant of the Taylor expansion term, This represents the phase change of the injected signal.

5. A novel micro-nano displacement self-feedback method for a high dynamic voice coil motor according to claim 4, characterized in that: The process of nonlinear compensation and correction of the high-frequency components includes: using a detection instrument in an offline state to correct the correlation function between the micro-displacement of the voice coil and the change in inductance, thereby further performing nonlinear compensation and correction.

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