CN102654535A - Intelligent sensing method based on magneto-rheological grease (liquid) and capacitance-type sensor thereof - Google Patents

Abstract

The invention provides a magneto-rheological intelligent sensing technology and designs an intelligent magneto-rheological capacitance-type sensor for accurately detecting a change condition of a magnetic field through detecting the change of capacitance values. A capacitor does not use the conventional electrolytes of mica and the like and utilizes a novel intelligent material, namely a magnetic rheological body (namely magnetic fluid). The magnetic rheological body is input into a magnetic rheological dielectric constant variable type capacitor designed by the invention, and then a variable capacitor is charged and discharged for one time, so as to finish the detection of a capacitor to be detected. The method adopts a time detection principle with a high accuracy in an electronic technology, overcomes the disadvantages that the stability of an amplifier in the conventional weak signal detection circuit is not good, the zero drift is great and the like, and has the advantages of simple circuit structure, high detection precision, high resolution ratio and the like. The intelligent magneto-rheological capacitance-type sensor designed by the invention can accurately detect the size of a magnetic field and the detection range is within 0-70000Gs.

Description

Intelligent sensing method and capacitance type sensor thereof based on magneto-rheological grease (liquid)

Affiliated technical field

The present invention relates to magnetic rheological body electromagnetics Characteristics Detection and magnetic rheological body intelligent sensing technical field, be specifically related to magnetorheological (body) condenser type intelligent sensing technology and application thereof, relate in particular to magneto-rheological grease (liquid) condenser type intelligent sensing technology and application thereof.

Background technology

Capacitance type sensor mainly contains changed area, clearance-changed type and three types on change specific inductive capacity type.Formerly to have temperature stability good, simple in structure for technology, and adaptability is strong, and dynamic response is fast, can realize advantages such as non-contact detecting (Dan Chengxiang, the theory of sensor and design basis and application thereof [M], National Defense Industry Press, 1999:3-30).Formerly the change specific inductive capacity type capacitance type sensor in the technology usually between two-plate zones of different be full of different electrolyte and realize its testing goal to change specific inductive capacity; Be mainly used in liquid level and flaky material thickness measure (Sun Shenghe; Modern sensor developing direction [J]; Electronic surveying and instrument journal, 2009,23:28-34).But, become specific inductive capacity type capacitance type sensor and can not carry out transition detection magnetic field not through regulating the magnetic rheological body capacitance type sensor that the magnetic field size changes specific inductive capacity.Along with electromagnetic development, the detection in magnetic field has been widely used in geophysics, space technology, military engineering, industry, biology, medical science, archaeology numerous areas.Therefore, significant to the research of intelligent magneto-rheological body capacitance formula sensor.

Magnetic rheological body mainly comprises magnetic flow liquid, two kinds of magnetic mediums of magneto-rheological grease.They are mainly formed by the small soft magnetic particles and the non-magnetic liquid mixing of high magnetic permeability, low stickiness.Under the effect of externally-applied magnetic field, can transform fast between the solid-state and liquid state, and this variation is controlled, continuous, reversible (M.A.Luque; M.P.P ' erez-P ' erez, et al, Brain Research Bulletin.Sci.; 2008,75:480-484), be widely used in field (Thomas H.Meedel such as machinery, automobile, aviation, Precision Machining, building, medical treatment; Patrick Chang; Et al. [J] .Developmental Biology.Sci., 2007,312:644-645).At present, the electromagnetics characteristic of magnetic rheological body also is not applied to capacitance type sensor and field of sensing technologies thereof.

Summary of the invention

For magnetic rheological body electromagnetics characteristic is applied to capacitance type sensor and intelligent sensing technical field thereof, the present invention proposes a kind of new magnetic rheological body intelligent sensing technology, and designs a kind of change specific inductive capacity type intelligent magneto-rheological body capacitance formula sensor.The inner electrolyte of this capacitance type sensor is magnetic medium a---magnetic rheological body, can obtain induction level through the change that detects capacitance.The measured magnetic rheological body capacitance range of the present invention is 0～several dried pF, and the scope of the magnetic induction density of detection is 0～7000Gs.

The technical scheme that the present invention adopted:

The technical scheme that the present invention adopted is made up of the change specific inductive capacity type capacitor design of magnetic rheological body and metering circuit two parts of magnetic rheological body electric capacity.

In order to address the above problem, the present invention designs a kind of change specific inductive capacity type variable condenser (with reference to shown in Figure 1) of magnetic rheological body, and inner the Sheng carried magnetic rheological body.It is characterized in that possessing:

This variable condenser comprises pole plate, and encapsulation two parts are formed.Two pole plates are parallel to each other, and one of them is a fixed plate, and another one is a movable plate electrode.Through the rotation movable plate electrode, can regulate two distances between pole plate, also fixing movable plate electrode.The screw-type structure is adopted in encapsulation, is convenient to the adjusting that polar plate spacing leaves.

Described plate material is an aluminium alloy, and ferroalloy, or titanium alloy are shaped as circle, and semicircle is square, and triangle and other are irregularly shaped.

Described encapsulating material is polymethylmethacrylate (organic glass), teflon or Kynoar, and in encapsulation, design screw thread.

Described magnetic rheological body can be magnetic flow liquid, or magneto-rheological grease, also magnetic fluid.

Magnetic rheological body capacitance measurement circuit part of the present invention (with reference to shown in Figure 2), by direct voltage source, DC current source; The change specific inductive capacity type capacitor of magnetic rheological body is housed, electronic switch K1, K2, operational amplifier; Put in advance, the A/D conversion, several parts of data handling system are formed.Its characteristics are to possess:

Current source is connected through electronic switch K1, K2 with the variable condenser that magnetic rheological body is housed to be measured and is constituted the closed-loop path; The two ends of variable condenser are connected to the input end of operational amplifier; Operational amplifier output terminal is through put in advance, and A/D conversion (analog/digital conversion) inserts data handling system.When K1 was closed, direct voltage source charged to Uc=Us to electric capacity.K1 breaks off then, and K2 is closed, and electric capacity discharges under the effect of current source, and the internal counter of data handling system part is started working simultaneously.When current source to capacitor discharge during to Uc=0, comparator toggles, counter finishes counting, count value is directly proportional with capacitor discharge time.The relation of capacitance voltage Uc and discharge current Io is:

$U_c=U_s-\frac{1}{C\left(B\right)}{\∫}_0^t{I}_0\mathrm{dt}---\left(1\right)$

Make Uc=0, then have:

$C\left(B\right)=\frac{I_{0}t}{U_s}=\frac{I_{0}N{T}_c}{U_s}---\left(2\right)$

N is the reading of counter in the formula, and Tc is the cycle (being a constant) of count pulse, I ₀Discharge current, t are discharge time, and Us is the voltage source output voltage, and C (B) is the capacitance of magnetorheological electric capacity.Uc is a charging voltage.Us and I ₀During for definite value, C (B) is directly proportional with N.B is an externally-applied magnetic field.

Described direct voltage source can provide lasting burning voltage.

Described DC current source adopts accurate constant current tube, and continuous steady current can be provided.

Described constant current tube model is 2DHL050, or 3CR3A, or 3CR3B, or 4DH7.

Described electronic switch K1, K2 are made up of triode.Through data handling system its disconnection of control and closure.

Describedly put in advance, can be by triode, FET or operational amplifier are formed.

Described data handling system can be by single-chip microcomputer, dsp processor, and virtual instrument or arm processor constitute.

The method that the present invention adopted:

According to above-mentioned detection device, the present invention further proposes a kind of intelligent sensing method based on magnetic rheological body, and this method may further comprise the steps:

(1) current source is connected through electronic switch K1, K2 with the change specific inductive capacity type capacitance type sensor that magnetic rheological body is housed to be measured constitutes the closed-loop path.

The two ends that (2) will become specific inductive capacity type capacitor are connected to the input end of operational amplifier.

(3) operational amplifier output terminal is received the input end of putting in advance, the output terminal of putting is in advance received the input end of A/D conversion (analog/digital conversion), and the output terminal of A/D conversion inserts data handling system.

(4) closed electronic switch K1, direct voltage source charges to Uc=Us to electric capacity, breaks off K1 then, and closed K2, electric capacity discharge under the effect of current source, and the internal counter of data handling system is started working simultaneously.

(5) capacitance size that becomes specific inductive capacity type capacitor into:

$C\left(B\right)=\mathrm{\ϵ}\left(B\right)\frac{S}{d}---\left(3\right)$

(6) bring (3) formula into (2) Shi Kede,

$\mathrm{\ϵ}\left(B\right)=\frac{I_0{\mathrm{NT}}_c}{U_s}\frac{d}{S}---\left(4\right)$

ε in the formula (B) is a specific inductive capacity, and d is a distance between the capacitor two-plate, and S is the pole plate area.

For with a kind of magnetic rheological body material, ε (B) is certain with the B relation, and ε (B) is as shown in Figure 3 with the relation of B.Joined and measured the capacitor C (B) that becomes specific inductive capacity type capacitor, can record ε (B), can know the externally-applied magnetic field size by Fig. 3.

Beneficial effect of the present invention:

The present invention proposes a kind of intelligent sensing method based on magnetic rheological body, and designs a kind of new intelligent magneto-rheological body capacitance formula sensor, can detect the size of treating measuring magnetic field in real time.Solve formerly and become the technical barrier that specific inductive capacity type capacitance type sensor can not detect the magnetic field size in the technology.

Description of drawings

The change specific inductive capacity type plane-parallel capacitor that accompanying drawing 1 the present invention makes.

The magnetic rheological body capacitance type sensor metering circuit figure of accompanying drawing 2 the present invention design.

Accompanying drawing 3 magnetic flow liquids under externally-applied magnetic field specific inductive capacity with the magnetic induction density change curve

Embodiment

For further specifying above-mentioned purpose of the present invention, technical scheme and effect, below combine above-mentioned each figure that invention is described in detail through instance.Please consult shown in Figure 1ly earlier, it is one can contain the change specific inductive capacity type capacitor that carries magnetic rheological body.Distance between pole plate is 1mm.

Said 1 is movable plate electrode, and it is shaped as circle, and material therefor is an aluminium alloy.

Said 2 is fixed plate, and it is shaped as circle, and material therefor is an aluminium alloy.

Said 3 for becoming the encapsulation of specific inductive capacity type capacitor.Material therefor is an organic glass.

Said 4 is magnetic flow liquid, and its performance parameter is following: null field viscosity: η 0≤1.5Pa.s; Shear stress: τ>=60kPa (B=0.5T); Temperature range :-40～130 ℃; Ms=379.64kA/m.

The metering circuit part of said variable condenser is as shown in Figure 2.

Said 1 is direct voltage source QJ5010XII, output voltage range: 0-50V.

Said 2 is DC current source QJ5010XII, output current scope: 0-10A.

Said 3 is operational amplifier OP27.

Said 4 is operational amplifier OP27.

Said 5 is A/D converter AD7705,16.

Said 6 is the TMS320DSP28335 embedded processing systems.TMS320DSP28335 is 32 floating type embedded chips, and its concrete technical parameter is following:

The FLASH:256K*16 position

The SRAM:34K*16 position

Boot ROM:816K position

The ePWM:12 road

SCI asynchronous serial port: 3 passages

McBSP synchronous serial interface: 2 passages

The DMA:6 passage

ECAN bus: 2 passages

Said 7 is circular parallel-plate variable condenser.

The relation of capacitance voltage Uc and discharge current Io is:

$U_c=U_s-\frac{1}{C\left(B\right)}{\∫}_0^t{I}_0\mathrm{dt}---\left(5\right)$

Make Uc=0, then have:

$C\left(B\right)=\frac{I_{0}t}{U_s}=\frac{I_{0}N{T}_c}{U_s}---\left(6\right)$

Shown in the specific inductive capacity of described magnetic flow liquid and externally-applied magnetic field relation curve Fig. 3, hence one can see that, and the electrolytical specific inductive capacity of magnetic rheological body is the function of magnetic induction density B, that is:

ε(B)＝f(B) (7)

Because:

$\mathrm{\ϵ}\left(B\right)=C\left(B\right)\frac{d}{S}---\left(8\right)$

So:

$\mathrm{\ϵ}\left(B\right)=\frac{I_0{\mathrm{NT}}_c}{U_s}\frac{d}{S}---\left(9\right)$

For with a kind of magnetic rheological body material, ε (B) is certain with the B relation, and ε (B) is as shown in Figure 3 with the relation of B.Through recording ε (B) thus obtain external magnetic field B.This sensing technology is magnetic rheological body intelligent sensing technology.

Claims (10)

1. the present invention designs a kind of intelligent magneto-rheological body capacitance formula sensor, and this invention comprises change specific inductive capacity type capacitor and the metering circuit two parts based on magnetic rheological body.It is characterized by:

Described change specific inductive capacity type capacitor, magnetic rheological body is filled with in inside.

Described change specific inductive capacity type capacitor is by fixed plate, and movable plate electrode encapsulates three parts and forms.

Described metering circuit is by current source, voltage source, and electronic switch amplifies in advance, the A/D conversion, several parts of data handling system are formed.Can detect the change of magnetic rheological body capacitance size in real time.

2. intelligent magneto-rheological body capacitance formula sensor according to claim 1 is characterized in that: described variable condenser is contained and is carried magnetic rheological body, and sped structure is adopted in the sealing of capacitor.

3. intelligent magneto-rheological body capacitance formula sensor according to claim 1 is characterized in that: described encapsulating material is polymethylmethacrylate (organic glass), teflon or Kynoar, and at the package design screw thread.Movable plate electrode is through the distance between screw thread scalable and fixed plate.

4. intelligent magneto-rheological body capacitance formula sensor according to claim 1, it is characterized in that: described plate material is an aluminium alloy, and ferroalloy, or titanium alloy are shaped as circle, and semicircle is square, triangle and other are irregularly shaped.

5. intelligent magneto-rheological body capacitance formula sensor according to claim 1, it is characterized in that: described magnetic rheological body is a magnetic flow liquid, magneto-rheological grease, or magnetic liquid.

6.

intelligent magneto-rheological body capacitance formula sensor according to claim 1; It is characterized in that: described measure portion; Electronic switch is through data handling system control; Data handling system can be by single-chip microcomputer; DSP, ARM or virtual instrument are formed.

7. intelligent magneto-rheological body capacitance formula sensor according to claim 1; It is characterized in that: described measure portion, measured capacitance only once discharge and recharge the detection that can accomplish measured capacitance.Adopted the higher time detecting principle of accuracy in the electronic technology, overcome stable bad, the shortcoming such as zero point drift is big of amplifier in the traditional detection feeble signal circuit, had that circuit structure is simple, accuracy of detection and a resolution advantages of higher.

8.

intelligent magneto-rheological body capacitance formula sensor according to claim 1; It is characterized in that: described measure portion, tested magnetorheological electric capacity size is:

$C\left(B\right)=\frac{I_{0}N{T}_c}{U_s}---\left(10\right)$

9.

intelligent magneto-rheological body capacitance formula sensor according to claim 1; It is characterized in that: described technical scheme comprises based on the design of magnetic rheological body specific inductive capacity type capacitor and detection two parts of magnetic rheological body electric capacity constituting.Become specific inductive capacity type capacitor and be used for containing a year magnetic rheological body, the detection system of magnetic rheological body electric capacity is used for measuring in real time the size of magnetic rheological body electric capacity.

10. intelligent magneto-rheological body capacitance formula sensor according to claim 1; It is characterized in that: described intelligent sensing method based on the magnetic rheological body capacitance characteristic is the change of the capacitance size through the magnetic rheological body capacitor and the size that the externally-applied magnetic field relation is surveyed magnetic field.

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