CN109059744A - Micro-displacement signal detection system and measurement method based on ADA2200 - Google Patents
Micro-displacement signal detection system and measurement method based on ADA2200 Download PDFInfo
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- CN109059744A CN109059744A CN201710442916.6A CN201710442916A CN109059744A CN 109059744 A CN109059744 A CN 109059744A CN 201710442916 A CN201710442916 A CN 201710442916A CN 109059744 A CN109059744 A CN 109059744A
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- signal
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- ada2200
- variation
- displacement
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
Abstract
The present invention relates to a kind of micro-displacement signal detection system and measurement method based on ADA2200, system include clock and the preposition processing module of driving pulse generation module, capacitance sensor, capacitive detection module, signal, ADA2200 synchronous demodulation module, A/D conversion module and single-chip microcontroller control and serial ports output unit；Clock and driving pulse generation module are for generating clock and ac-excited signal；Relative displacement between pole plate is converted to the variation of capacitor by capacitance sensor；Capacitive detection module is used to be converted to the variation of capacitor the variation of voltage；The preposition processing module of signal is used to carry out preposition amplification and low-pass filtering treatment to analog signal；ADA2200 synchronous demodulation module is for carrying out simulation synchronous demodulation to filtered signal；A/D conversion module then carries out analog-to-digital conversion to the analog signal demodulated, to obtain digital signal.The present invention has many advantages, such as measurement accuracy height, strong antijamming capability, Digital output.
Description
Technical field
The present invention relates to the online measuring techniques of accurate displacement, and in particular to a kind of microbit shifting signal based on ADA2200
Detection system and measurement method.
Background technique
Based on the astronomical telescope of active optics technology, need actively to adjust the state of the sub- mirror of every module unit, to correct certain
Kind optical aberration realizes certain optical surface profile.For this purpose, it is adjacent to detect generally to install precise displacement sensor between adjacent sub- mirror
The difference in height at sub- mirror edge, to carry out feedback control.
Active optics technology includes two parts: segmented mirror and thin mirror surface technology.To by segmented mirror and thin mirror surface
Technology uses simultaneously, needs mirror surface very thin, therefore just tight to the size and weight of the sensor for being fixed on the sub- mirror back side or edge
Lattice limitation, the otherwise overweight deformation that will cause thin mirror surface of sensor, and this deformation is the force actuator institute in thin mirror surface technology
It cannot be modified.
It is poor for the Eddy Current Type sensor stability of use at present, and major astronomical telescope is had been used in the world
In displacement sensor cannot meet segmented mirror simultaneously again in weight, volume and precision and wanted with what thin mirror surface technology combined
It asks, therefore proposes to study a kind of novel capacitive displacement transducer, it is desirable that miniaturization, light weight, Wide measuring range, and precision
It is higher, and there is low reading error, effect on environment has stronger immunocompetence.
Summary of the invention
The purpose of the present invention is to provide a kind of micro-displacement signal detection system and measurement method based on ADA2200, solution
Precision existing for certainly existing precise displacement sensor is not high, stability is poor, complex structure and other problems.
Realize the technical solution of the object of the invention are as follows: a kind of micro-displacement signal detection system based on ADA2200, including base
In CPLD clock and the preposition processing module of driving pulse generation module, capacitance sensor, capacitive detection module, signal,
ADA2200 synchronous demodulation module, A/D conversion module and single-chip microcontroller control and serial ports output unit；
The ac-excited signal of clock needed for the CPLD is used for generation system and capacitance sensor；
The capacitance sensor is difference variable area formula structure, for converting the variation of relative displacement between capacitor plate
For the transformation of capacitor；
The capacitive detection module is arranged after capacitance sensor, and the change of voltage is converted into for the variation by capacitor
Change；
The preposition processing module of signal is used to carry out preposition amplification and low pass to the analog signal for carrying out self capacitance sensor
Filtering processing；
The ADA2200 synchronous demodulation module is used to carry out analog demodulator to above-mentioned filtered signal, obtains capacitance pole
The relative shift of plate；
The A/D conversion module is used to carry out analog-to-digital conversion to the analog signal after demodulation, obtains digital signal；
The single-chip microcontroller control and serial ports output unit are used to control ADA2200 synchronous demodulation module and A/D conversion module,
And result output.
A kind of micro-displacement signal detecting method based on said detecting system, comprising the following steps:
Step 1, CPLD generates double frequency both-end reverse energization signal, drives to capacitance sensor；
Step 2, in conjunction with switched capacitor technique and operational amplifier formula capacitance determining method, the variation of capacitor is converted into electricity
The variation of pressure；
Step 3, above-mentioned analog voltage signal is subjected to preposition amplification and low-pass filtering；
Step 4, the signal from step 3 is carried out by analog demodulator by ADA2200, then low-pass filtering obtains useful position
Move information；
Step 5, A/D conversion is carried out to the simulation shift value that step 4 provides, obtains digital signal, then exported by single-chip microcontroller
To external equipment.
Compared with prior art, remarkable advantage of the invention are as follows: (1) present invention using both-end with same frequency and reversed-phase driven,
While to maximum excitation, system is improved to the rejection ability of noise；(2) present invention carries out electricity using switched capacitor technique
Hold detection, because it increases signal amplitude by metal-oxide-semiconductor driving device, to improve the sensitivity of sensor；(3) of the invention
The ADA2200 chip of use can synchronize demodulation to modulated signal, can change at any time chip parameter by SPI interface and set
It sets, to reach best demodulation effect；(4) present invention is using single-chip microcontroller to signal demodulation chip ADA2200 and A/D converter
Parameter setting is carried out, easy to operate, modification is conveniently.
Detailed description of the invention
Fig. 1 is that the present invention is based on the functional block diagrams of the micro-displacement signal detection system of ADA2200.
Fig. 2 is that the present invention is based on the flow charts of the micro-displacement signal detecting method of ADA2200.
Fig. 3 is the same frequency both-end reverse phase driving pulse schematic diagram that the present invention uses.
Fig. 4 is the driving pulse amplitude lift circuit that the present invention uses.
Fig. 5 is the capacitive detection circuit figure that the present invention uses.
Fig. 6 is the functional block diagram for the ADA2200 chip that the present invention uses.
Specific embodiment
In conjunction with Fig. 1, Fig. 2, a kind of micro-displacement signal detection system based on ADA2200 of the invention, including it is based on CPLD
Clock and the preposition processing module of driving pulse generation module, capacitance sensor, capacitive detection module, signal, ADA2200 it is synchronous
Demodulation module, A/D conversion module and single-chip microcontroller control and serial ports output unit；
The ac-excited signal of clock needed for the CPLD is used for generation system and capacitance sensor；
The capacitance sensor is difference variable area formula structure, for converting the variation of relative displacement between capacitor plate
For the transformation of capacitor；Capacitance sensor is made of three pieces of pole plates, including two pieces of small pole plates and one piece with both have positive area
Big pole plate.When horizontal displacement occurs for small pole plate and big pole plate, two groups of plates capacitance values can generate variation therewith；
The capacitive detection module is arranged after capacitance sensor, and the change of voltage is converted to for the variation by capacitor
Change；
The preposition processing module of signal is used to carry out preposition amplification and low pass to the analog signal for carrying out self capacitance sensor
Filtering processing；
The ADA2200 synchronous demodulation module is used to carry out analog demodulator to above-mentioned filtered signal, obtains capacitance pole
The relative shift of plate；
The A/D conversion module is used to carry out analog-to-digital conversion to the analog signal after demodulation, obtains digital signal；
The single-chip microcontroller control and serial ports output unit are used to control ADA2200 synchronous demodulation module and A/D conversion module,
And result output.
Further, the preposition processing module of the signal includes preposition differential amplification module and low-pass filtering module；It is preposition
Differential amplification module is for amplifying the voltage signal obtained of capacitance detecting before；Low-pass filtering module is for filtering off height
Frequency noise.
Further, the ADA2200 synchronous demodulation module includes ADA2200 chip demodulation module and low-pass filtering mould
Block；ADA2200 chip demodulation module use phase sensitive detection principle, on the basis of Parameter adjustable to pretreated signal into
Row simulation synchronous demodulation；The low-pass filtering module is used to filter off the garbage of high frequency, leaves useful low frequency displacement signal.
Further, the single-chip microcontroller control and serial ports output unit include control module and result output unit；
Data write-in and the control of A/D converter of the control module for ADA2200；As a result output unit is for passing through
Computer is outputted results to by RS232 serial ports after data input single-chip microcontroller after crossing AD conversion.
The displacement signal detection method based on ADA2200 that the present invention also provides a kind of, comprising the following steps:
Step 1, CPLD is generated with frequency both-end reverse phase pumping signal, is driven to capacitance sensor；
Step 2, switched capacitor technique and operational amplifier formula capacitance determining method is used in combination to carry out capacitance detecting, incites somebody to action
The variation of capacitor is converted to the variation of voltage；
Step 3, preposition amplification and low-pass filtering are carried out to analog voltage signal；
Step 4, analog demodulator is carried out to preposition treated signal using ADA2200 chip, then is obtained by low-pass filtering
To useful displacement information；
Step 5, the simulation shift value provided to step 4 carries out A/D conversion, obtains defeated by single-chip microcontroller again after digital signal
External equipment is arrived out.
Further, in step 2 capacitance detecting method are as follows:
By operational amplifier formula capacitance determining method by the change of capacitor while metal-oxide-semiconductor is driven sensor as switch
Change the variation for being converted into voltage；
The switched capacitor technique increases signal amplitude by metal-oxide-semiconductor driving device, improves the sensitivity of sensor；
The operational amplifier formula capacitance determining method, will be to be measured using the characteristic of operational amplifier high-amplification-factor, high input impedance
Displacement is converted to voltage signal output, solves the linear problem of sensor output.
Further, the detailed process that advance signal is handled in step 3 are as follows:
Step 301, the preposition differential amplification of signal, to improve detection sensitivity and be further reduced noise；
Step 302, low pass signal filters, to filter out high-frequency noise；
Further, the analog demodulator of ADA2200 chip is that the base of parameter setting has been carried out to it in single-chip microcontroller in step 4
It is carried out on plinth, then realizes the acquisition of low frequency displacement information using low-pass filtering method.
Further, step 5 by RS232 interface by the digital signal after AD conversion, that is, the shift value that measures from
Single-chip microcontroller is exported to external equipment.
Invention is further explained with reference to the accompanying drawings and examples.
Embodiment
As shown in Figure 1 and Figure 2, a kind of micro-displacement signal detection system and measurement method based on ADA2200, system schema
Including following sections:
(1) CPLD is generated with frequency both-end reverse phase pumping signal, is reduced as far as possible while driving to sensor
Influence of noise；
(2) capacitance sensor of difference variable area formula structure carries out sensing to capacitance and reduces ring to a certain extent
Influence of the border factor to testing result；
(3) switched capacitor technique and operational amplifier formula capacitance determining method is used in combination in capacitive detection module, by capacitor
Variation be converted to the variation of voltage；
(4) preposition processing module has carried out preposition amplification and low-pass filtering treatment to analog signal；
(5) ADA2200 chip realizes that the simulation of modulated signal is same on the basis of single-chip microcontroller has carried out parameter setting to it
Step demodulation, then useful displacement information is obtained by low-pass filtering；
(6) A/D conversion module carries out analog-to-digital conversion to the analog signal after demodulation, obtains digital signal and exports to monolithic
Machine；
(7) digital signal after AD conversion is exported from single-chip microcontroller to external equipment by RS232 interface.
As shown in figure 3, the same frequency both-end that the present invention uses is driven in the reverse direction pulse frequency 10kHz, wherein V1, V2 are with frequency
Reversed AC signal.
As shown in Figure 4, Figure 5, switched capacitor technique and operation amplifier is used in combination in the capacitive detection module that the present invention uses
Device formula capacitance determining method passes through operational amplifier formula capacitor while increasing sensitivity of the signal amplitude to improve sensor
Detection method shows the variation of capacitor by the variation of voltage value.In Fig. 4, VPMIt is DC power supply, it determines driving
The amplitude of device output, V is seed pulse, VoutIt is output；V in Fig. 51, V2It is all generated by CPLD with reset pulse signal, V1, V2
It is exactly reverse impulse described above, reset signal is then using the switching effect of metal-oxide-semiconductor come to CfCapacitor carries out charge and discharge, with
Realize the periodical output of voltage.
As shown in fig. 6, the phase sensitive detection principle that ADA2200 chip synchronizes demodulation is as follows:
(1) capacitance parameter passes through in carrier frequency fMODExcitation under sensor be converted into being displaced to the electricity of carrier frequency
Signal is pressed, and is transmitted to ADA2200 chip input terminal；
(2) bandpass filter BPF removes part out-of-band noise；
(3) signal frequency is shifted back direct current by synchronous demodulator；
(4) low-pass filter LPF removes most of remaining high-frequency noise.
Wherein the working principle of synchronous demodulator is as follows:
The signal of synchronous demodulator output end C is the product of reference signal Yu bandpass filter output end B signal.If ginseng
Examining signal is a sine wave, and physical parameter is constant, and noise, and the signal of bandpass filter output end are not present in system
It is sine wave, enables its expression are as follows:
In formula, VBFor the amplitude of sine wave, ωREFFor the modulating frequency of whole system,For the phase of the signal.
Then synchronous demodulator exports are as follows:
In formula, VREFFor the amplitude of reference signal,For the phase of reference signal.
The signal is the AC signal of a direct current signal and a twice reference frequency.If low-pass filter
It is enough to remove AC signal, then the signal of first low pass filter output D are as follows:
Compared to other methods, more preferably sensitivity can get using synchronous demodulation in sensor signal conditioning technology.Together
Step demodulation increases two considerable advantages, can restore small sensor output signal in the presence of having noise, first excellent
Gesture is to joined pumping signal, can be transferred to sensor output signal in lower noise band；Second advantage is synchronous
Simple low-pass filter can be achieved in demodulation, removes the residual interference noise contribution of the overwhelming majority.
Claims (5)
1. a kind of micro-displacement signal detection system based on ADA2200, which is characterized in that including based on CPLD clock and driving
The preposition processing module of pulse generation module, capacitance sensor, capacitive detection module, signal, ADA2200 synchronous demodulation module, A/D
Conversion module and single-chip microcontroller control and serial ports output unit；
The clock and driving pulse generation module are for the ac-excited of clock and capacitance sensor needed for generation system
Signal；
The capacitance sensor is difference variable area formula structure, for the variation of relative displacement between capacitor plate to be converted to electricity
The transformation of appearance；
The capacitive detection module is arranged after capacitance sensor, and the variation of voltage is converted into for the variation by capacitor；
The preposition processing module of signal is used to carry out preposition amplification and low-pass filtering to the analog signal for carrying out self capacitance sensor
Processing；
The ADA2200 synchronous demodulation module is used to carry out analog demodulator to above-mentioned filtered signal, obtains capacitor plate
Relative shift；
The A/D conversion module is used to carry out analog-to-digital conversion to the analog signal after demodulation, obtains digital signal；
The single-chip microcontroller control and serial ports output unit are used to control ADA2200 synchronous demodulation module and A/D conversion module, and
As a result it exports.
2. a kind of micro-displacement signal detecting method based on detection system described in claim 1, which is characterized in that including following step
It is rapid:
Step 1, CPLD generates double frequency both-end reverse energization signal, drives to capacitance sensor；
Step 2, in conjunction with switched capacitor technique and operational amplifier formula capacitance determining method, the variation of capacitor is converted into voltage
Variation；
Step 3, above-mentioned analog voltage signal is subjected to preposition amplification and low-pass filtering；
Step 4, the signal from step 3 is carried out by analog demodulator by ADA2200, then low-pass filtering obtains useful displacement letter
Breath；
Step 5, A/D conversion is carried out to the simulation shift value that step 4 provides, obtains digital signal, then exported to outer by single-chip microcontroller
Portion's equipment.
3. micro-displacement signal detecting method according to claim 2, which is characterized in that combine switching capacity skill in step 2
Art and operational amplifier formula capacitance determining method pass through operational amplifier formula while metal-oxide-semiconductor is driven sensor as switch
The variation of capacitor is converted to the variation of voltage by capacitance determining method.
4. micro-displacement signal detecting method according to claim 2, which is characterized in that pass through single-chip microcontroller pair in step 4
ADA2200 chip carries out parameter setting and combines low-pass filter circuit, realizes the demodulation to signal.
5. micro-displacement signal detecting method according to claim 2, which is characterized in that step 5 passes through RS232 interface for institute
The shift value of measurement is exported to external equipment.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110361999A (en) * | 2019-06-13 | 2019-10-22 | 南京理工大学 | Active optics micro-displacement sensor signal processing system and method based on DSP |
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| CN110361999A (en) * | 2019-06-13 | 2019-10-22 | 南京理工大学 | Active optics micro-displacement sensor signal processing system and method based on DSP |
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