CN110907866B - Working point real-time optimization system of giant magneto-impedance sensor and giant magneto-impedance sensor - Google Patents
Working point real-time optimization system of giant magneto-impedance sensor and giant magneto-impedance sensor Download PDFInfo
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- CN110907866B CN110907866B CN201911281756.7A CN201911281756A CN110907866B CN 110907866 B CN110907866 B CN 110907866B CN 201911281756 A CN201911281756 A CN 201911281756A CN 110907866 B CN110907866 B CN 110907866B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
- G01R33/063—Magneto-impedance sensors; Nanocristallin sensors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/0023—Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration
- G01R33/0041—Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration using feed-back or modulation techniques
Abstract
The invention discloses a working point real-time adjusting and optimizing system of a giant magneto-impedance sensor, which comprises a control unit, an excitation signal unit and a bias coil driving unit, wherein the control unit is used for controlling the excitation signal unit to generate an excitation signal with adjustable frequency and amplitude; the control unit is used for controlling the bias coil driving unit to generate a driving signal with adjustable amplitude. The invention also discloses a tuning method, which comprises the following steps: s01, generating an excitation signal with frequency and amplitude changing regularly; or/and generating a driving signal with amplitude changing according to a rule; and S02, when the change rate of the response signal is reduced whether the excitation signal or/and the driving signal is adjusted up or down, taking the excitation signal or/and the driving signal at the moment as the working parameter. The invention also discloses a giant magneto-impedance sensor which comprises an amorphous wire, a signal pickup coil, a bias coil and the tuning system. The scheme has the advantages of high automation degree, application in different environments to improve sensitivity and the like.
Description
Technical Field
The invention mainly relates to the technical field of giant magneto-impedance sensors, in particular to a system and a method for adjusting and optimizing a working point of a giant magneto-impedance sensor in real time and the giant magneto-impedance sensor.
Background
For a magnetic field detection probe based on giant magneto-impedance effect (GMI), the working performance of the magnetic field detection probe is determined by a plurality of factors such as the size of an amorphous wire, the winding mode of a signal pickup coil, the arrangement of an amorphous wire excitation signal and a bias magnetic field, the external temperature and humidity and the like. In practical application, as the hardware structure of one probe is solidified, the method for enabling the probe to reach the optimal working point at the moment mainly changes the excitation signal of the amorphous wire and applies a bias magnetic field to the working environment of the amorphous wire.
In the conventional design, the excitation signal and the bias magnetic field of the amorphous wire are set to obtain substantially better values after initial experiments, and then are solidified in the circuit. Although the circuit formed by the method is simplified and small, the amorphous wire can not reach the optimal working point generally, and when the external conditions change, corresponding adjustment can not be made, so that the working performance of the probe is very unstable, in a patent of 'bridge type resistance giant magneto-impedance effect magnetic field sensor' applied by the physical research of the local ball of earthquake districts in 2013, a feedback coil is additionally arranged outside a signal pickup coil and a bias coil, and the temperature stability and frequency response of the magnetic probe are enhanced to a certain extent by reversely connecting the output of a post-stage amplifier back to the feedback coil. However, the feedback loop of the hardware solidification can only improve the stability and sensitivity of the probe to a small extent, and cannot enable the probe to always maintain an optimal working point; secondly, the feedback loop of the hardware solidification has limited performance and can not be adjusted, and a more optimized control algorithm can not be added into the feedback loop.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: aiming at the technical problems in the prior art, the invention provides a working point real-time optimization system and method of a giant magneto-impedance sensor, which have high automation degree and are applied to different environments to improve the sensitivity, and the giant magneto-impedance sensor.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a working point real-time tuning system of a giant magneto-impedance sensor comprises a control unit, an excitation signal unit and a bias coil driving unit, wherein the control unit is connected with the excitation signal unit and is used for controlling the excitation signal unit to generate an excitation signal with adjustable frequency and amplitude so as to excite an amorphous wire of the giant magneto-impedance sensor; the control unit is connected with the bias coil driving unit and used for controlling the bias coil driving unit to generate driving signals with adjustable amplitude so as to drive the bias coil of the giant magneto-impedance sensor.
As a further improvement of the above technical solution:
the driving signal unit includes a first DA output unit and a first operational amplifier.
The bias coil driving unit includes a second DA output unit and a second operational amplifier.
The device also comprises a magnetic field generating unit which is used for generating a magnetic field to be tested with adjustable strength so as to test the performance of the giant magneto-impedance sensor.
The magnetic field generating unit comprises a third operational amplifier and a magnetic field generating coil, wherein the input end of the third operational amplifier is connected with the control unit, and the output end of the third operational amplifier is connected with the magnetic field generating coil.
The control unit is a microcontroller for acquiring a signal pickup coil response signal of the giant magneto-impedance sensor.
The invention also discloses an adjusting method of the working point real-time adjusting system based on the giant magneto-impedance sensor, which comprises the following steps:
s01, controlling the excitation signal to generate an excitation signal with frequency and amplitude changing according to rules through a control unit so as to excite the amorphous wire of the giant magneto-impedance sensor; or/and
the control unit controls the bias coil driving unit to generate a driving signal with amplitude changing according to a rule so as to drive the bias coil of the giant magneto-impedance sensor;
and S02, acquiring a response signal of the giant magneto-impedance sensor, and taking the excitation signal or/and the driving signal as the working parameters of the giant magneto-impedance sensor under the condition that the change rate of the corresponding response signal is reduced no matter the excitation signal or/and the driving signal are adjusted up or down in the step S01.
As a further improvement of the above technical solution:
under the condition that the change rate of the response signal is improved, the frequency and the amplitude of the excitation signal or/and the amplitude of the driving signal are adjusted upwards in a fixed period and step length changing mode; and under the condition that the change rate of the response signal is reduced, the frequency and the amplitude of the excitation signal or/and the amplitude of the driving signal are adjusted downwards in a fixed period and step-length changing mode.
The invention also discloses a giant magneto-impedance sensor which comprises an amorphous wire, a signal pickup coil, a bias coil and the working point real-time adjusting and optimizing system of the giant magneto-impedance sensor.
As a further improvement of the above technical solution:
the signal pickup coil is connected with the control unit through a signal processing unit and an AD conversion unit in sequence.
Compared with the prior art, the invention has the advantages that:
(1) starting with the dynamic change of the angles of the amorphous wire excitation signal and the bias magnetic field, the sensitivity of the response signal of the giant magneto-impedance sensor is enabled to be highest through the adjustment of the excitation signal or/and the drive signal, so that the work of the giant magneto-impedance sensor is adjusted to be at the optimal point; the whole tuning system has simple structure, simple and convenient operation and easy realization; the tuning process is realized by an automatic control program in the control unit, and the degree of automation is high.
(2) The invention utilizes the microcontroller which is originally only used for a data receiving end to expand to generate an excitation signal and a driving signal, and realizes the function of automatically adjusting the working point under the condition of hardly increasing the volume of the probe; a programmable microcontroller is brought into an amorphous wire optimization feedback loop, so that the defect that the feedback regulation performance is limited by using pure hardware originally is avoided.
(3) The tuning method is automatically completed in the control unit, and can realize automatic real-time tuning of the working point of the giant magneto-impedance sensor; automatic closed-loop control is realized through automatic adjustment between output signals (excitation signals and driving signals) and input signals (response signals); in addition, the optimization can be applied in different environments, the optimal working point can be achieved, the environmental adaptability and the stability are high, the whole process can be automatically executed, and manual intervention is not needed.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment of the system of the present invention.
FIG. 2 is a method flow diagram of an embodiment of the method of the present invention.
Illustration of the drawings: 1. a control unit; 2. an excitation signal unit; 201. a first DA output unit; 202. a first operational amplifier; 3. a bias coil driving unit; 301. a second DA output unit; 302. a second operational amplifier; 4. amorphous wire; 5. a bias coil; 6. a signal pickup coil; 7. a signal processing unit; 8. an AD conversion unit; 9. a magnetic field generation unit; 901. a third operational amplifier; 902. a magnetic field generating coil.
Detailed Description
The invention is further described below with reference to the figures and the specific embodiments of the description.
As shown in fig. 1, the system for adjusting the working point of the giant magneto-impedance sensor in real time according to the present embodiment includes a control unit 1, an excitation signal unit 2 and a bias coil driving unit 3, where the control unit 1 is connected to the excitation signal unit 2 and is configured to control the excitation signal unit 2 to generate an excitation signal with adjustable frequency and amplitude to excite an amorphous wire 4 of the giant magneto-impedance sensor; the control unit 1 is connected with the bias coil driving unit 3 and is used for controlling the bias coil driving unit 3 to generate a driving signal with adjustable amplitude so as to drive a bias coil 5 of the giant magneto-impedance sensor; through the adjustment of the excitation signal or/and the driving signal, when the sensitivity of the response signal of the giant magneto-impedance sensor is highest, the parameter at the moment is taken as the working optimal point of the giant magneto-impedance sensor; the whole tuning system has simple structure, simple and convenient operation and easy realization.
In the present embodiment, the excitation signal unit 2 includes a first DA output unit 201 and a first operational amplifier 202; the bias coil driving unit 3 includes a second DA output unit 301 and a second operational amplifier 302. The first DA output unit 201 and the second DA output unit 301 may control a digital-to-analog converter built in the unit 1, or may adopt an external independent digital-to-analog conversion unit. A digital-to-analog converter arranged in the control unit 1 is utilized to output a variable current with the highest waveform frequency reaching MHz level and controllable amplitude under the drive of a timer, and the power of the variable current is increased through a corresponding operational amplifier and is directly used as an excitation signal of the amorphous wire 4 or a drive signal of the bias coil 5.
In this embodiment, the apparatus further includes a magnetic field generating unit 9, configured to generate a magnetic field to be tested with adjustable strength to perform a performance test on the giant magneto-impedance sensor. Specifically, the magnetic field generating unit 9 includes a third operational amplifier 901 and a magnetic field generating coil 902, and the input end of the third operational amplifier 901 is connected to the control unit 1, and the output end is connected to the magnetic field generating coil 902. The strength of the magnetic field to be tested can be adjusted by changing the output voltage of the test signal output port in the control unit 1 and the resistance value of the resistor in the test loop.
In this embodiment, the control unit 1 is a microcontroller for acquiring a response signal of the signal pickup coil 6 of the giant magneto-impedance sensor. The signal pickup coil 6 is connected to an input port of the control unit 1 via a signal processing unit 7 (e.g., filtering, amplifying, detecting, amplifying, etc.) and a high-precision AD conversion unit 8 in this order. After the response signal collected by the signal pickup coil 6 passes through the filtering amplification/detection amplification circuit, the response signal is converted into a digital signal by a high-precision AD conversion unit 8 (analog-to-digital converter AD) connected to the microcontroller and stored in the memory of the microcontroller. The microcontroller which is originally only used for a data receiving end is expanded to generate an excitation signal and a driving signal, so that the function of automatically adjusting a working point is realized under the condition of hardly increasing the volume of the probe; the programmable microcontroller is brought into the amorphous wire 4 tuning feedback loop, so that the defect of limited feedback regulation performance of the original pure hardware is avoided.
As shown in fig. 2, the present invention also discloses a tuning method of the working point real-time tuning system based on the giant magneto-impedance sensor, which comprises the following steps:
s01, controlling the excitation signal unit to generate an excitation signal with frequency and amplitude changing regularly through the control unit 1 to excite the amorphous wire 4 of the giant magneto-impedance sensor; or/and
the control unit 1 controls the bias coil driving unit 3 to generate a driving signal with amplitude changing according to a rule so as to drive the bias coil 5 of the giant magneto-impedance sensor;
and S02, acquiring a response signal of the giant magneto-impedance sensor, and when the change rate of the corresponding response signal is reduced no matter the excitation signal or/and the driving signal is adjusted up or down in the step S01, taking the excitation signal or/and the driving signal as the optimal working parameter of the giant magneto-impedance sensor, and then acquiring data according to the optimal working parameter.
The tuning method is automatically completed in the control unit 1, and the real-time tuning of the working point of the giant magneto-impedance sensor can be realized; automatic closed-loop control is realized through automatic adjustment between output signals (excitation signals and driving signals) and input signals (response signals); in addition, the optimization can be applied in different environments, the optimal working point can be achieved, the environmental adaptability and the stability are high, the whole process can be automatically executed, and manual intervention is not needed.
In this embodiment, under the condition that the change rate of the response signal is increased, the frequency and the amplitude of the excitation signal or/and the amplitude of the driving signal are adjusted upwards in a fixed period and step length changing manner; and under the condition that the change rate of the response signal is reduced, the frequency and the amplitude of the excitation signal or/and the amplitude of the driving signal are adjusted downwards in a fixed period and step-length changing mode.
As shown in fig. 2, the DA output signal can be used as an excitation signal for the amorphous wire 4 (in this case, the frequency and amplitude of the output signal can be adjusted), or can be used to drive the bias coil 5 (in this case, the amplitude of the output signal is adjusted, not the frequency), or can be outputted in a dual-path manner, and both signals can be simultaneously included in the feedback loop. Through the increase and decrease fluctuation of the fixed period and the variable step length of the frequency (or amplitude) of the single or two output signals, the increase and decrease of the change rate (sensitivity) of the corresponding response signals are analyzed and compared, when the response signals are all reduced in sensitivity regardless of the up-regulation or the down-regulation of the output signals, the output signals at the moment are optimal, the parameters of the output signals at the moment are recorded, and then the subsequent acquisition and recording of the response signals are carried out according to the parameters.
The invention further discloses a giant magneto-impedance sensor which comprises an amorphous wire 4, a signal pickup coil 6, a bias coil 5 and the working point real-time adjusting and optimizing system of the giant magneto-impedance sensor. The signal pickup coil 6 and the bias coil 5 are both wound on the amorphous wire 4, and the signal pickup coil 6 is connected with the control unit 1 through the signal processing unit 7 and the AD conversion unit 8 in sequence. The sensor of the invention comprises a tuning system as described above, also with the advantages as described above for the tuning system.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make numerous possible variations and modifications to the present invention, or modify equivalent embodiments to equivalent variations, without departing from the scope of the invention, using the teachings disclosed above. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention should fall within the protection scope of the technical scheme of the present invention, unless the technical spirit of the present invention departs from the content of the technical scheme of the present invention.
Claims (10)
1. The system for adjusting and optimizing the working point of the giant magneto-impedance sensor in real time is characterized by comprising a control unit (1), an excitation signal unit (2) and a bias coil driving unit (3), wherein the control unit (1) is connected with the excitation signal unit (2) and is used for controlling the excitation signal unit (2) to generate an excitation signal with adjustable frequency and amplitude so as to excite an amorphous wire (4) of the giant magneto-impedance sensor; the control unit (1) is connected with the bias coil driving unit (3) and is used for controlling the bias coil driving unit (3) to generate a driving signal with adjustable amplitude so as to drive a bias coil (5) of the giant magneto-impedance sensor;
and adjusting the excitation signal or/and the driving signal, and taking the parameter at the moment as the optimal working point of the giant magneto-impedance sensor when the sensitivity of the response signal of the giant magneto-impedance sensor is highest.
2. The operating point real-time tuning system of giant magneto-impedance sensor according to claim 1, characterized in that the excitation signal unit (2) comprises a first DA output unit (201) and a first operational amplifier (202).
3. The operating point real-time tuning system of a giant magneto-impedance sensor according to claim 1, wherein the bias coil driving unit (3) comprises a second DA output unit (301) and a second operational amplifier (302).
4. The system for real-time tuning of operating point of a giant magneto-impedance sensor according to claim 1, 2 or 3, further comprising a magnetic field generating unit (9) for generating a magnetic field to be tested with adjustable intensity to perform performance test on the giant magneto-impedance sensor.
5. The system for real-time tuning of operating point of giant magneto-impedance sensor according to claim 4, wherein the magnetic field generating unit (9) comprises a third operational amplifier (901) and a magnetic field generating coil (902), wherein the input end of the third operational amplifier (901) is connected to the control unit (1), and the output end is connected to the magnetic field generating coil (902).
6. The system for real-time tuning of the operating point of giant magneto-impedance sensors according to claim 1, 2 or 3, characterized in that the control unit (1) is a microcontroller that acquires the response signal of the signal pickup coil (6) of the giant magneto-impedance sensor.
7. A tuning method of the operating point real-time tuning system based on the giant magneto-impedance sensor as claimed in any one of claims 1 to 6, comprising the steps of:
s01, controlling the excitation signal to singly generate an excitation signal with frequency and amplitude changing according to rules through a control unit (1) so as to excite the amorphous wire (4) of the giant magneto-impedance sensor; or/and
the control unit (1) controls the bias coil driving unit (3) to generate a driving signal with amplitude changing according to a rule so as to drive a bias coil (5) of the giant magneto-impedance sensor;
and S02, acquiring a response signal of the giant magneto-impedance sensor, and taking the excitation signal or/and the driving signal as the working parameters of the giant magneto-impedance sensor under the condition that the change rate of the corresponding response signal is reduced no matter the excitation signal or/and the driving signal are adjusted up or down in the step S01.
8. A tuning method according to claim 7, characterized in that the frequency and amplitude of the excitation signal, or/and the amplitude of the drive signal, are adjusted upwards in a periodic and step-wise manner in response to an increase in the rate of change of the signal; and under the condition that the change rate of the response signal is reduced, the frequency and the amplitude of the excitation signal or/and the amplitude of the driving signal are adjusted downwards in a fixed period and step-length changing mode.
9. A giant magneto-impedance sensor comprising an amorphous wire (4) and a signal pick-up coil (6), characterized by further comprising a bias coil (5) and a real-time tuning system of the operating point of the giant magneto-impedance sensor according to any one of claims 1 to 6.
10. A giant magneto-impedance sensor according to claim 9, characterized in that the signal pick-up coil (6) is connected to the control unit (1) via a signal processing unit (7) and an AD conversion unit (8) in sequence.
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| CN101975934B (en) * | 2010-09-27 | 2012-11-14 | 上海交通大学 | Integrated bias coil type giant magneto-impedance effect (GMI) magneto-dependent sensor |
| CN203310984U (en) * | 2013-05-03 | 2013-11-27 | 中国地震局地球物理研究所 | Bridge type resistor giant magneto-impedance effect magnetic field sensor |
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