CN214795617U

CN214795617U - FPGA-based three-point piezoelectric drive fast-swing mirror hysteresis compensation control system

Info

Publication number: CN214795617U
Application number: CN202120210135.6U
Authority: CN
Inventors: 张泉; 李清灵; 魏传新; 尹达一
Original assignee: Shanghai Institute of Technical Physics of CAS
Current assignee: Shanghai Institute of Technical Physics of CAS
Priority date: 2021-01-26
Filing date: 2021-01-26
Publication date: 2021-11-19
Anticipated expiration: 2031-01-26

Abstract

The patent discloses a FPGA-based three-point piezoelectric-driven fast oscillating mirror hysteresis compensation control system, which comprises an FPGA hysteresis compensation control module, an SGS micro-displacement sensor, an SGS micro-displacement signal conditioning and collecting circuit, a piezoelectric ceramic driving circuit, an upper computer and a three-point piezoelectric-driven fast oscillating mirror, wherein the three-point piezoelectric-driven large-caliber fast oscillating mirror is a controlled object; the SGS micro-displacement sensor is integrated in the piezoelectric ceramic actuator; the SGS micro-displacement signal conditioning and acquiring circuit is connected with the FPGA hysteresis compensation control module; the piezoelectric ceramic driving circuit is connected with the FPGA hysteresis compensation control module; and the upper computer is communicated with the FPGA through a 422 interface. The system fully utilizes the parallel processing characteristic of the FPGA, completes the deployment of a PI inverse model based on the parallel connection of multiple Stop operators on the FPGA and the parallel hysteresis compensation control of the multi-piezoelectric ceramic actuator, reduces the calculation delay of the system, improves the response speed of the system, and realizes the high-precision, real-time and synchronous multi-piezoelectric compensation and control.

Description

FPGA-based three-point piezoelectric drive fast-swing mirror hysteresis compensation control system

The technical field is as follows:

the patent relates to a piezoelectric driving fast oscillating mirror, in particular to a three-point piezoelectric driving fast oscillating mirror hysteresis compensation control system based on an FPGA.

Background art:

the on-orbit working environment of the space astronomical telescope is very complex, the detection precision of the detector can be influenced by various complex factors, and in order to ensure high-quality imaging and long-time stability of the detector of the telescope, on the basis of adopting technical means such as high-precision attitude control and vibration suppression of an aircraft and the like, the influence of various disturbance sources on the space astronomical telescope needs to be eliminated by means of a precision image stabilizing technology. A Large-aperture fast-swinging mirror (LAFSM) is a key component of a space astronomical telescope precision image stabilizing system, and performs image motion compensation on visual axis offset detected and fed back by a Fine satellite guide (FGS), so that residual visual axis errors of a pointing tracking system can be effectively inhibited, and high-precision image stabilization is realized.

With the rapid development of the nanometer-scale positioning technology, the nanometer-scale piezoelectric precision driving technology has gradually become a key technology in the field of modern precision positioning and measurement. The piezoelectric ceramic actuator has the advantages of high response frequency, large load, high displacement resolution and the like, has higher resonant frequency and displacement resolution compared with a Voice Coil motor (VCA), and is a driving device commonly used by a fast-swinging mirror actuating mechanism in an image stabilizing system. However, the inherent hysteresis nonlinearity of the piezoceramic actuator can adversely affect the accuracy of the fast-oscillating mirror image motion compensation and reduce the performance of the image stabilization system.

A Field Programmable Gate Array (FPGA) belongs to one of Application Specific Integrated Circuits (ASICs) with the highest integration level, and is internally composed of a large number of basic logic units. The FPGA has rich I/O resources and can be flexibly configured, so that the FPGA can be conveniently connected with peripheral devices. The user can reconfigure logic resources, I/O resources and the like in the FPGA to customize functions required by the user, thereby greatly improving the flexibility of system design and shortening the design cycle of products. Different from the technical principle of sequentially executing instructions such as DSP and ARM, the FPGA can realize real parallel operation. At present, the advanced FPGA comprises a hardware core with a digital signal processing function, and the optimized hardware DSP module can improve the clock frequency in the data operation process, so that the high-speed complex hysteresis compensation operation can be stably executed. Therefore, the FPGA is adopted to complete the deployment of the PI inverse model based on the parallel connection of the multiple Stop operators in the FPGA, and the parallel hysteresis compensation and control of the multiple piezoelectric ceramic actuators in the three-point drive fast swing mirror are realized.

The invention content is as follows:

to the above-mentioned application background, this patent provides a three point piezoelectric drive fast pendulum mirror hysteresis compensation control system based on FPGA's high accuracy, quick response, the system includes three point piezoelectric drive fast pendulum mirror 1, SGS micro displacement sensor (Resistance train gain sensor)2, SGS signal conditioning and acquisition circuit 3, piezoceramics drive circuit 4, FPGA hysteresis compensation control module 5 and host computer 6. The upper computer 6 sends a target swing angle signal of the fast oscillating mirror to the FPGA hysteresis compensation control module 5 through a 422 communication interface, wherein the displacement calculation calculates the swing angle into target displacements of three-point piezoelectric ceramic actuators, the target displacements are inversely solved through a hysteresis compensation algorithm to obtain driving voltages of the piezoelectric ceramic actuators, and the piezoelectric ceramic driving circuit 4 controls the rotation angle of the three-point piezoelectric driven fast oscillating mirror 1, so that the nonlinear compensation of piezoelectric ceramic hysteresis is realized; the SGS micro-displacement sensor 2 is responsible for detecting the displacement of the piezoelectric ceramic actuator in real time, inputs a displacement signal into the FPGA hysteresis compensation control module through the SGS signal conditioning and collecting circuit 3, and transmits the displacement signal to the upper computer 6 through the 422 communication interface, so that the real-time monitoring of the displacement of the piezoelectric ceramic actuator is completed.

Preferably, the three-point piezoelectric driving fast oscillating mirror 1 uses piezoelectric ceramic actuators as actuators, the mirror surface is driven by a flexible supporting micro-displacement amplification mechanism, the two-dimensional deflection of the mirror surface adopts a three-point parallel driving mode, the three piezoelectric ceramic actuators are distributed around the center of the mirror surface in an equilateral triangle shape, and the included angle between every two actuators and the central connecting line is 120 degrees.

Preferably, the piezoelectric ceramic driving circuit 4 is connected with the FPGA hysteresis compensation control module 5, and is composed of three mutually independent driving channels, and is used for parallel driving of the three-point piezoelectric ceramic actuators. The circuit further comprises a piezoelectric ceramic driving power supply and a 16bits DAC, wherein the piezoelectric ceramic driving power supply is connected with the 16bits DAC, and the output voltage of the DAC is amplified by adopting a composite secondary amplifier, so that the driving of the piezoelectric driving fast swing mirror is realized.

Preferably, the SGS signal conditioning and acquisition circuit 3 is connected to the FPGA hysteresis compensation control module 5, and is composed of three independent detection and acquisition channels for parallel detection of actual displacement of the three-point piezoelectric ceramic actuator. The circuit further comprises a signal conditioning module and an 18bits ADC, wherein the signal conditioning module is used for converting a differential voltage signal output by the SGS displacement sensor into a single-ended output, and denoising and amplifying a detected weak displacement signal through a narrow-band Butterworth low-pass filter; the 18bits ADC is of a differential input type, a single-end voltage needs to be converted into a differential voltage input before analog-to-digital conversion, and the differential voltage input is used for converting a displacement analog signal detected by the SGS into a digital signal and accessing the digital signal into the FPGA hysteresis compensation control module.

Preferably, the FPGA hysteresis compensation control module 5 implements a parallel hysteresis compensation and control algorithm of the multi-piezoelectric ceramic actuator by using the FPGA, completes deployment of a PI (Prandtl-Ishlinskii) inverse model based on parallel connection of multiple Stop operators in the FPGA by using a VHDL language, and a coefficient of the PI inverse model needs to be calibrated in advance by using an intelligent optimization algorithm according to acquired input voltage-output displacement data. The polynomial orders and coefficients of the ascending section and the descending section of the curve in the PI inverse hysteresis model expression based on the parallel connection of the multiple Stop operators can be adaptively adjusted by an intelligent optimization algorithm to enhance the universality of different hysteresis characteristic curves, so that the hysteresis nonlinear compensation precision of the algorithm is improved.

The parallel computing advantage of the FPGA is fully utilized, the system computing time delay is reduced, the system response speed is improved, and high-precision, real-time and synchronous multi-voltage compensation and control are realized.

Description of the drawings:

FIG. 1 is a block diagram of a three-point piezoelectric driving fast oscillating mirror hysteresis compensation control system.

Fig. 2 is a block diagram of a piezoelectric hysteresis compensation method.

FIG. 3 is a diagram of an inverse model of PI for the modified Stop operator.

FIG. 4 is a diagram of the FPGA hysteretic compensation control module software architecture.

The specific implementation mode is as follows:

this patent adopts the mode of the hysteresis compensation of inverse model to eliminate piezoceramics hysteresis nonlinearity, utilizes PI hysteresis inverse model to carry out the inverse solution to the piezoceramics executor target displacement that the displacement calculation module obtained and obtains drive voltage and export through 16bits D/A acquisition circuit, drives piezoceramics executor through piezoceramics drive power supply to realize the linearization of target output and actual output, as shown in figure 2.

The input of the conventional hysteresis model is the drive voltage and the output is the displacement, while the input of the inverse hysteresis model is the displacement and the output is the drive voltage. Aiming at the problem of building the piezoelectric hysteresis inverse model, in order to avoid a complex inversion process and the restriction on constraint conditions, the piezoelectric hysteresis inverse model is directly modeled by adopting a PI inverse model based on the parallel connection of multiple Stop operators. The Stop operator is based on elastic-plastic behavior in continuous medium mechanics, and the discrete mathematical form of the Stop operator is shown as the formula (1):

Er(0)＝min{r_i,max{-r_i,y(k)+Er0}}

Er(k)＝min{r_i,max{-r_i,y(k)-y(k-1)+Er(k-T)}} (1)

wherein r is_iIs the operator threshold, N is the number of operators, i is more than or equal to 1 and less than or equal to N, Er0 is the operator initial value, and y (k) is the output displacement. Since the input voltage to the piezoelectric actuator is positive, the single-sided form using the Stop operator is:

Er(0)＝min{r_i,max{0,y(k)+Er0}}

Er(k)＝min{r_i,max{0,y(k)-y(k-1)+Er(k-T)}} (2)

the Stop operator in the formula (2) cannot effectively fit the asymmetric inverse hysteresis loop, so that the basic Stop operator is improved, as shown in the formula (3):

Er(k)＝min{r_i,max{0,f(k)-f(k-1)+Er(k-T)}}

f_l(y(k))＝a₁[y(k)]³+a₂[y(k)]²+a₃y(k)+a₄

f_r(y(k))＝b₁[y(k)]³+b₂[y(k)]²+b₃y(k)+b₄ (3)

in the formula (f)_r(y (k)) is an output displacement representation of the falling segment of the inverse hysteresis curve, f_l(y (k)) is an output displacement representation of the rising segment of the inverse hysteresis curve, a₁～a₄,b₁～b₄Are polynomial coefficients and are all positive values.

The improved Stop operator of the formula (3) is subjected to weighted superposition to establish an improved PI inverse model:

r_i＝ci (4)

where q is the initial load curve weight, y (k) is the output displacement, ω_iIs the operator weight, N represents the number of operators, τ, ρ, c are coefficients and are all normal numbers, and the structure of the inverse model of PI based on the improved Stop operator is shown in fig. 3.

For piezoelectric ceramic actuators of different processes, hysteresis characteristic curves are different, and polynomial orders and coefficients of ascending sections and descending sections of the hysteresis curves are different when the polynomial orders and the coefficients are reflected on a model expression. Utilizing the input voltage-output displacement curve of the piezoelectric ceramic actuator which is acquired in advance and carrying out a-axis optimization algorithm on the a in the model₁～a₄,b₁～b₄Q, tau, rho, c, to achieve adaptive fitting of the piezoelectric hysteresis curve, and will identifyAnd importing the good parameters into the established FPGA hysteresis inverse model module to complete the algorithm model deployment based on the FPGA platform, wherein the software architecture is shown in FIG. 4.

The SGS micro-displacement sensor is responsible for detecting the expansion amount of the piezoelectric ceramic actuator in real time, the displacement signal is input into the FPGA through the SGS signal conditioning and collecting circuit, and is transmitted to the upper computer through the 422 communication interface, so that the real-time monitoring of the displacement of the piezoelectric ceramic actuator is completed.

Claims

1. A three-point piezoelectric driving fast oscillating mirror hysteresis compensation control system based on FPGA comprises a three-point piezoelectric driving fast oscillating mirror (1), an SGS micro-displacement sensor (2), an SGS signal conditioning and collecting circuit (3), a piezoelectric ceramic driving circuit (4), an FPGA hysteresis compensation control module (5) and an upper computer (6); the method is characterized in that:

the upper computer (6) sends a target swing angle signal of the fast-swinging mirror to the FPGA hysteresis compensation control module (5) through a 422 communication interface, wherein displacement calculation is used for calculating a mirror surface swing angle into target displacement of three-point piezoelectric ceramic actuators, the target displacement is subjected to inverse solution through a hysteresis compensation algorithm to obtain driving voltage of each piezoelectric ceramic actuator, and the piezoelectric ceramic driving circuit (4) is used for controlling the rotation angle of the fast-swinging mirror, so that the nonlinear compensation of piezoelectric ceramic hysteresis is realized; the SGS micro-displacement sensor (2) is responsible for detecting the expansion amount of the piezoelectric ceramic actuator in real time, and displacement signals are input into the FPGA hysteresis compensation control module through the SGS signal conditioning and collecting circuit (3) and are transmitted to the upper computer (6) through the 422 communication interface, so that the real-time monitoring of the displacement of the piezoelectric ceramic actuator is completed.

2. The FPGA-based three-point piezoelectric driven fast oscillating mirror hysteresis compensation control system as defined in claim 1, wherein the three-point piezoelectric driven fast oscillating mirror (1) uses a piezoelectric ceramic actuator as an actuator to drive the mirror surface through a flexible support micro-displacement amplification mechanism, the two-dimensional deflection of the mirror surface adopts a three-point parallel driving mode, the three piezoelectric ceramic actuators are distributed in an equilateral triangle around the center of the mirror surface, and the included angle between each two actuators and the central connecting line is 120 °.

3. The FPGA-based three-point piezoelectric driven fast oscillating mirror hysteresis compensation control system of claim 1, wherein the piezoelectric ceramic driving circuit (4) is connected with the FPGA hysteresis compensation control module (5), and the piezoelectric ceramic driving circuit (4) is composed of three mutually independent driving channels and is used for driving the three-point piezoelectric ceramic actuators in parallel.

4. The FPGA-based three-point piezoelectric driven fast-swinging mirror hysteresis compensation control system according to claim 1, wherein the SGS signal conditioning and acquisition circuit (3) is connected with the FPGA hysteresis compensation control module (5), and the SGS signal conditioning and acquisition circuit (3) is composed of three mutually independent detection and acquisition channels and is used for parallel detection of actual displacement of the three-point piezoelectric ceramic actuator.

5. The FPGA-based three-point piezoelectric driving fast oscillating mirror hysteresis compensation control system according to claim 1 or 3, wherein the piezoelectric ceramic driving circuit (4) further comprises a piezoelectric ceramic driving power supply and a 16bits DAC, the piezoelectric ceramic driving power supply is connected with the 16bits DAC, and a composite secondary amplifier is adopted to amplify the output voltage of the DAC, so that the driving of the piezoelectric driving fast oscillating mirror is realized.

6. The FPGA-based three-point piezoelectric driven fast-swinging mirror hysteresis compensation control system as claimed in claim 1 or 4, wherein the SGS signal conditioning and acquisition circuit (3) further comprises a signal conditioning module and an 18bits ADC, the signal conditioning module is used for converting a differential voltage signal output by the SGS displacement sensor into a single-ended output, and denoising and amplifying a detected weak displacement signal through a narrow-band Butterworth low-pass filter; the 18bits ADC is of a differential input type, a single-end voltage needs to be converted into a differential voltage input before analog-to-digital conversion, and the differential voltage input is used for converting a displacement analog signal detected by the SGS into a digital signal and accessing the digital signal into the FPGA hysteresis compensation control module.