CN101769712B - X-Y-Theta displacement direct decoupling measuring device and method based on plane capacitor - Google Patents

Abstract

The invention discloses a X-Y-Theta displacement direct decoupling measuring device and a method based on plane capacitors. The X-Y-Theta displacement direct decoupling measuring device consists of a moving polar plate and a fixed polar plate, wherein four groups of capacitor-electrode banks which are arranged in a quadrate shape are arranged on the fixed polar plate; four groups of sensing capacitor-electrode banks (eight in total) which are in one-to-one correspondence with the capacitor-electrode banks arranged on the fixed polar plate are arranged on the moving polar plate, and the initial positions of the two capacitor-electrode banks in one group in the corresponding measuring direction have a position difference of one quarter of period, making output signals have a phase difference of 90 degrees; in the process of measurement, when the moving polar plate generates plane displacement relatively to the fixed polar plate, the eight sensing capacitor-electrode banks generate eight capacitance output signals, X-axis and Y-axis plane displacement output signals can be directly decoupled through product-to-sum calculation under small-angle displacement so as to obtain a small angle displacement signal theta. The method can directly decouple to output X-axis and Y-axis displacement signals and the small-angle displacement signal theta, and has a high measuring speed.

Description

X-Y-θ displacement direct decoupling measuring device and method based on plane capacitance

Technical field

The present invention relates to a kind of X-Y-θ displacement direct decoupling measuring device and method based on plane capacitance.

Background technology

The accurate displacement measuring technique is to assemble and the closely-related new and high technologies of numerous areas development level such as integrated, ultraprecise processing, nano material manufacturing, optical instrument, cell operation, bioengineering with VLSI (very large scale integrated circuit) (IC) manufacturing and encapsulation, MEMS (micro electro mechanical system) (MEMS).The top priority of accurate displacement measuring technique is when keeping high-acruracy survey, breaks through the bottleneck of big stroke measurment.

At present, using the most widely, the accurate displacement measuring method comprises: optical measuring method, inductance measuring (Linear Variable Differential Transformer, LVDT, linear variable difference transformer), resistance method of temperature measurement and capacitance measurement etc.Optical measuring method and capacitance measurement are relatively ripe, are most widely used in the market two kinds of accurate displacement measuring methods.Optical measuring method mainly comprises grating measuring method and laser interferance method, characteristics such as both all have the measuring accuracy height, response speed is fast, range is big, nothing wearing and tearing, it is high that but optical measuring method requires environmental factors such as temperature, humidity, and the cost of system constructing is also higher.For the measurement by capacitance method, main at present the application becomes the space type measuring principle, and its advantage is the resolution height, precision is good, simple in structure, dynamic response is fast, is particularly suitable for kinetic measurement, but it is less to measure stroke.

Planar capacitance sensor is based on the high-acruracy survey sensor of capacitance principle, is expected to become a kind of new accurate displacement measuring method that breaks through big stroke, high precision bottleneck.Based on the planar capacitance sensor of variable area formula, when keeping accurate capacitive transducer advantage, can realize that the accurate displacement of big stroke is measured.Because the two-dimentional straight-line displacement that it only needs to adopt a sensor just can realize X-Y is simultaneously measured, requirements of installation space, alignment error (having eliminated Abbe error) reduce greatly simultaneously.

But planar capacitance sensor is to the requirement height of installation accuracy, and less angle tilt error (having had the rotating deviation around three coordinate axis X, Y, Z in the installation) will reduce the linearity of output signal greatly.And in the application of reality, angular deviation (or claiming to disturb) is inevitably, comprises installation deviation (static error), kinematic error (dynamic error) etc.At installation deviation, though can reduce as far as possible, can't eliminate fully by demarcating, and the safeguard measure difficulty of process aspect, cost is also higher.The angular deviation that kinematic error causes is a dynamic disturbance, although can improve by real-time feedback compensation, can cause system to become too complicated, realizes difficulty.

Summary of the invention

The purpose of this invention is to provide a kind of X-Y-θ displacement direct decoupling measuring device and method based on plane capacitance.Based on the plane capacitance measuring principle, except that realizing that X-Y two dimensional surface accurate displacement is measured, utilize eight groups of sensing electrode group simple geometric relations on the mobile pole plate simultaneously, output signal is adopted " with the difference eliminate indigestion " algorithm, the angle undesired signal is considered as low-angle displacement signal θ, decoupling zero low-angle displacement signal θ exports the low-angle displacement signal simultaneously in real time to the influence of X-Y two dimensional surface displacement signal, has realized the measurement of X-Y-θ displacement direct decoupling.

The technical solution adopted for the present invention to solve the technical problems is:

One, a kind of X-Y-θ displacement direct decoupling measuring device based on plane capacitance:

Measurement mechanism comprises a fixed polar plate and places a mobile pole plate of fixed polar plate top abreast; Be distributed with the capacitance electrode group that four groups of square symmetry distribute on the fixed polar plate, every group of capacitance electrode group all be by wait size, equidistant, etc. the square capacitance electrode unit of number constitute; Be distributed with on the mobile pole plate with fixed polar plate on capacitance electrode group four groups of totally eight sensing capacitance electrode groups one to one, comprise the sensing electrode group SENSE of output X-axis displacement signal _X1N, SENSE _X1Q, SENSE _X2N, SENSE _X2QAnd the sensing electrode group SENSE of output Y-axis displacement signal _Y1N, SENSE _Y1Q, SENSE _Y2NAnd SENSE _Y2Q, SENSE wherein _X1N, SENSE _X1QBe one group, SENSE _X2N, SENSE _X2QBe one group, SENSE _Y1N, SENSE _Y1QBe one group, SENSE _Y2N, SENSE _Y2QBe last group; There is the alternate position spike in 1/4 cycle in two sensing capacitance electrode groups of each group at the initial position of corresponding direction of measurement, make output signal that 90 ° phase differential, SENSE be arranged _X1N, SENSE _X2N, SENSE _Y1NAnd SENSE _Y2NThe output cosine signal, SENSE _X1Q, SENSE _X2Q, SENSE _Y1QAnd SENSE _Y2QThe output sinusoidal signal.

Eight sensing capacitance electrode groups on the described mobile pole plate, all comprise two groups of totally six capacitance electrode unit separately, capacitance electrode unit on the mobile pole plate is identical with capacitance electrode cell size on the fixed polar plate, when wherein one group the capacitance electrode unit in totally three capacitance electrode unit and the fixed polar plate fully over against the time, another group totally three capacitance electrode unit just in time with fixed polar plate in the capacitance electrode unit stagger fully, not over against area.On the mobile pole plate electrode unit of every group of sensing electrode group and fixed polar plate top electrode unit over against area only when its direction of measurement produces displacement respective change takes place just at mobile pole plate, and be not subjected to the influence of change in location on the non-direction of measurement.

Two, a kind of X-Y-θ displacement direct decoupling measuring method based on plane capacitance:

The mobile pole plate of plane capacitance and place fixed polar plate top abreast; Be distributed with the capacitance electrode group that four groups of square symmetry distribute on the fixed polar plate, every group of capacitance electrode group all be by wait size, equidistant, etc. the square capacitance electrode unit of number constitute; Be distributed with on the mobile pole plate with fixed polar plate on capacitance electrode group four groups of totally eight sensing capacitance electrode groups one to one, there is the alternate position spike in 1/4 cycle in two sensing capacitance electrode groups of each group at the initial position of corresponding direction of measurement, make output signal that 90 ° phase differential be arranged; Simultaneously, eight sensing capacitance electrode groups, all comprise two groups of totally six capacitance electrode unit separately, when wherein one group the capacitance electrode unit in totally three capacitance electrode unit and the fixed polar plate fully over against the time, another group totally three capacitance electrode unit just in time with fixed polar plate in the capacitance electrode unit stagger fully, not over against area; This has just guaranteed the SENSE of output X-axis displacement signal _X1N, SENSE _X1Q, SENSE _X2N, SENSE _X2QSENSE with the displacement signal of exporting Y direction _Y1N, SENSE _Y1Q, SENSE _Y2N, SENSE _Y2QAll only reflect the change in displacement of direction of measurement separately, and can not be subjected to the influence of non-direction of measurement top offset, realized that the direct decoupling of X-axis and Y-axis displacement is measured; When mobile pole plate relative fixed pole plate produces in-plane displancement, eight sensing capacitance electrode groups will produce eight electric capacity output signals, by simple and poor eliminate indigestion computing, but there is the X-axis Y-axis in-plane displancement output signal under the low-angle displacement interference in direct decoupling, and draws this low-angle displacement signal θ.

When the mobile pole plate of planar capacitance sensor when X-direction produces displacement with respect to fixed polar plate, sensing capacitance electrode group SENSE _X1NAnd SENSE _X2NOutput cosine curve signal, sensing capacitance electrode group SENSE _X1QAnd SENSE _X2Q1/4 cycle of backwardness output sinusoidal signal, SENSE _Y1N, SENSE _Y1Q, SENSE _Y2NAnd SENSE _Y2QSignal does not change; When the mobile pole plate of planar capacitance sensor when Y direction produces displacement with respect to fixed polar plate, sensing capacitance electrode group SENSE _Y1NAnd SENSE _Y2NOutput cosine curve signal, sensing capacitance electrode group SENSE _Y1QAnd SENSE _Y2Q1/4 cycle of backwardness output sinusoidal signal, SENSE _X1N, SENSE _X1Q, SENSE _X2NAnd SENSE _X2QSignal does not change; This has just guaranteed the SENSE of output X-axis displacement signal _X1N, SENSE _X1Q, SENSE _X2N, SENSE _X2QSENSE with the displacement signal of exporting Y direction _Y1N, SENSE _Y1Q, SENSE _Y2N, SENSE _Y2QAll only reflect the change in displacement of direction of measurement separately, and can not be subjected to the influence of non-direction of measurement top offset, realized that the direct decoupling of X-axis and Y-axis displacement is measured.

When there is a less deflection angular displacement (generally θ＜1 °) in mobile pole plate, be example with clockwise θ angular deflection, on X-direction, will make SENSE _X1NAnd SENSE _X2QOutput signal have an X _θThe phase place of/P is leading, SENSE _X1QAnd SENSE _X2NOutput signal an X is then arranged _θ/ P phase lag; On the Y direction, SENSE _Y1NAnd SENSE _Y2QOutput signal have a Y _θThe phase place of/P is leading, SENSE _Y1QAnd SENSE _Y2NOutput signal a Y is then arranged _θ/ P phase lag.Described X-Y-θ displacement direct decoupling measuring method based on plane capacitance is passed through the operational method of " with the difference eliminate indigestion ", and full decoupled low-angle displacement signal obtains the numerical value of low-angle displacement θ simultaneously in real time to the influence of X-axis and Y-axis displacement measurement.

The beneficial effect that the present invention has is:

1) only need sensor of employing just can realize the in-plane displancement dimension displacement measurement of X-Y, change in location on the mobile pole plate on the electric capacitance change of the every group of sensing electrode group reflected measurement direction, and be not subjected to the influence of change in location on the non-direction of measurement, realized that the direct decoupling of X-axis and Y-axis displacement is measured.

2) eight groups of signals to eight groups of sensing electrode group outputs on the mobile pole plate adopt " with the difference eliminate indigestion " algorithm, decoupling zero low-angle displacement signal θ is to the influence of X-Y two dimensional surface displacement signal, export low-angle displacement signal θ simultaneously in real time, realized the measurement of X-Y-θ displacement direct decoupling.

Description of drawings

Fig. 1 is a structural front view of the present invention.

Fig. 2 is the structure vertical view of Fig. 1.

Fig. 3 is sensing capacitance electrode group SENSE _Y1NAnd SENSE _Y1QThe structure of models front view

Fig. 4 is the structure vertical view of Fig. 3.

Fig. 5 is when having the low-angle displacement, sensing capacitance electrode group SENSE _Y1NAnd SENSE _Y1QThe structure of models vertical view.

Among the figure: 1, mobile pole plate, 2, fixed polar plate, 3, sensing capacitance electrode group SENSE _Y1N, 4, sensing capacitance electrode group SENSE _X2Q, 5, sensing capacitance electrode group SENSE _X2N, 6, sensing capacitance electrode group SENSE _Y2Q, 7, sensing capacitance electrode group SENSE _Y2N, 8, sensing capacitance electrode group SENSE _X1Q, 9, sensing capacitance electrode group SENSE _X1N, 10, sensing capacitance electrode group SENSE _Y1Q, 11, fixed polar plate capacitance electrode group.

Embodiment

As shown in Figure 1 and Figure 2, the mobile pole plate 1 of plane capacitance places the top of fixed polar plate 2 abreast.1) be distributed with the capacitance electrode group 11 that four groups of square symmetry distribute on the fixed polar plate 2, every group of capacitance electrode group all be by wait size, equidistant, etc. the square capacitance electrode unit of number constitute, unify input voltage signal V _Input2) be distributed with on the mobile pole plate 1 with fixed polar plate 2 on capacitance electrode group four groups of totally eight sensing capacitance electrode groups one to one, comprise the sensing electrode group SENSE of output X-axis displacement signal _X1N9, SENSE _X1Q8, SENSE _X2N5, SENSE _X2Q4 and the sensing electrode group SENSE of output Y-axis displacement signal _Y1N3, SENSE _Y1Q10, SENSE _Y2N7 and SENSE _Y2Q6, SENSE wherein _X1N9, SENSE _X1Q8 is one group, SENSE _X2N5, SENSE _X2Q4 is one group, SENSE _Y1N3, SENSE _Y1Q10 is one group, SENSE _Y2N7 and SENSE _Y2Q6 is last group; There is the alternate position spike in 1/4 cycle in two sensing capacitance electrode groups of each group at the initial position of corresponding direction of measurement, make output signal that 90 ° phase differential, SENSE be arranged _X1N9, SENSE _X2N5, SENSE _Y1N3 and SENSE _Y2N7 output cosine signals, SENSE _X1Q8, SENSE _X2Q4, SENSE _Y1Q10 and SENSE _Y2Q6 output sinusoidal signals.

Eight sensing capacitance electrode groups on the described mobile pole plate 1, all comprise two groups of totally six capacitance electrode unit separately, capacitance electrode unit on the mobile pole plate 1 is identical with capacitance electrode cell size on the fixed polar plate 2, when wherein one group the capacitance electrode unit in totally three capacitance electrode unit and the fixed polar plate 2 fully over against the time, another group totally three capacitance electrode unit just in time with fixed polar plate 2 in the capacitance electrode unit stagger fully, not over against area.

When the mobile pole plate 1 of planar capacitance sensor when X-direction produces displacements with respect to fixed polar plate 2, sensing capacitance electrode group SENSE _X1N9 and SENSE _X2N5 output cosine curve signals, sensing capacitance electrode group SENSE _X1Q8 and SENSE _X2Q4 fall behind 1/4 cycle output sinusoidal signal, SENSE _Y1N3, SENSE _Y1Q10, SENSE _Y2N7 and SENSE _Y2Q6 signals do not change; When the mobile pole plate 1 of planar capacitance sensor when Y direction produces displacements with respect to fixed polar plate 2, sensing capacitance electrode group SENSE _Y1N3 and SENSE _Y2N7 output cosine curve signals, sensing capacitance electrode group SENSE _Y1Q10 and SENSE _Y2Q6 fall behind 1/4 cycle output sinusoidal signal, SENSE _X1N9, SENSE _X1Q8, SENSE _X2N5, SENSE _X2Q4 signals do not change; This has just guaranteed the SENSE of output X-axis displacement signal _X1N9, SENSE _X1Q8, SENSE _X2N5, SENSE _X2Q4 and the SENSE of displacement signal of output Y direction _Y1N3, SENSE _Y1Q10, SENSE _Y2N7 and SENSE _Y2Q6 all only reflect the change in displacement of direction of measurement separately, and can not be subjected to the influence of non-direction of measurement top offset, have realized that the direct decoupling of X-axis and Y-axis displacement is measured.

Fig. 3 and Fig. 4 have provided the SENSE of output Y direction displacement signal on the mobile pole plate _Y1N3, SENSE _Y1Q10 structure of models front view and vertical views.On the mobile pole plate 1, sensing capacitance electrode group SENSE _Y1N3 and SENSE _Y1Q10 exist the alternate position spike in 1/4 cycle at the Y direction initial position, when mobile pole plate 1 from position as shown in Figure 4 when the Y-axis positive dirction produces displacement, SENSE _Y1N3 with fixed polar plate 2 on the capacitance electrode unit over against the form of area with triangular wave, change SENSE to minimum value from maximal value _Y1Q10 with fixed polar plate 2 on the capacitance electrode unit then fall behind SENSE over against area _Y1NIn 1/4 cycle, the form with triangular wave changes equally, considers the existence of edge effect, and actual capacitance signal more approaches to be sinusoidal and cosine curve changes, to SENSE _Y1N3, SENSE _Y1QAfter 10 output signal is carried out normalized, SENSE _Y1N3 will export cosine signal Y _1N, SENSE _Y1Q10 output sinusoidal signal Y _1Q

$Y_{1N}=\cos \left[2\mathrm{\π}\frac{\left(Y_{\mathrm{NORMINAL}}\right)}{P}\right]---\left(1\right)$

$Y_{1Q}=\sin \left[2\mathrm{\π}\frac{\left(Y_{\mathrm{NORMINAL}}\right)}{P}\right]$

Wherein, Y _NORMINALMove the displacement of pole plate for Y direction.

The SENSE of the mobile pole plate 1 output Y direction displacement signal that provides from Fig. 4 _Y1N3, SENSE _Y1QThe vertical view of 10 structural models also as can be seen, the sensing electrode group SENSE on the mobile pole plate 1 _Y1N3 and SENSE _Y1Q10 equal each self-contained six capacitance electrode unit, according to the relative position of arranging, six capacitance electrode unit in every group of sensing capacitance electrode group can be divided into two groups again.With SENSE _Y1N3 is example, works as SENSE _Y1NWhen the right one column capacitance electrode unit of 3 is just in time relative with the capacitance electrode unit in the fixed polar plate 2, the left side one column capacitance electrode unit just in time with fixed polar plate 2 in the capacitance electrode unit stagger.The design of this dislocation makes when mobile pole plate 1 moves on X-direction, the sensing capacitance electrode group SENSE on the mobile pole plate 1 _Y1NWith remaining unchanged over against area of capacitance electrode unit on the fixed polar plate 2, electric capacity does not change.That is: when displacement that mobile pole plate 1 produces on the non-direction of measurement of sensing capacitance electrode group, the electric capacity of sensing capacitance electrode group is not influenced by it.

When there is the low-angle displacement at a θ angle in mobile pole plate 1, on the mobile pole plate 1 four groups the output signal of totally eight sensing capacitance electrode groups can produce the leading or phase lag of a phase place separately, make and the X-Y plane displacement measurement signal low-angle displacement signal θ error that has been coupled reduced measuring accuracy.Fig. 5 has provided and has had sensing capacitance electrode group SENSE under the low-angle displacement signal θ _Y1N3, SENSE _Y1Q10 models.When mobile pole plate 1 produces desirable displacement Y along the Y-axis positive dirction _NORMINALThe time, if exist simultaneously the displacement of a low-angle θ deflection angle, the deflection meeting of mobile pole plate 1 make every group of sensing capacitance electrode group along direction of motion produce one displacement again again, for the displacement of Y direction, the deflection at θ angle makes SENSE _Y1N3 produce the displacement Y along the Y-axis forward _θ, and SENSE _Y1Q10 generations are along the displacement Y of Y-axis negative sense _θ, for two groups of output signals, directly performance is exactly SENSE _Y1N3 output signal has a Y _θThe phase place of/P is leading, and SENSE _Y1Q10 output signal then has a Y _θThe phase lag of/P.Based on the designed model of Fig. 3, provided on the Y direction sensing capacitance electrode group (SENSE when mobile pole plate 1 produces displacement _Y1N, SENSE _Y1Q) output signal:

$Y_{1N}=C\left(\mathrm{\θ}\right)\·\cos \left[2\mathrm{\π}\frac{(Y_{\mathrm{NORMINAL}}+Y_{\mathrm{\θ}})}{P}\right]---\left(2\right)$

$Y_{1Q}=C\left(\mathrm{\θ}\right)\·\sin \left[2\mathrm{\π}\frac{(Y_{\mathrm{NORMINAL}}-Y_{\mathrm{\θ}})}{P}\right]$

Wherein C (θ) is the sensitivity factor of influence of angular deflection to sensing capacitance electrode group; Y _θThe biasing displacement Y that the deflection at finger θ angle produces Y direction sensing capacitance electrode group along Y direction _θ

As can be seen from Figure 2, four groups of totally eight sensing capacitance electrode groups have been installed on the mobile pole plate 1, have comprised the SENSE of output X-axis displacement signal sensing capacitance electrode group _X1N9, SENSE _X1Q8, SENSE _X2N5, SENSE _X2Q4 and the sensing capacitance electrode group SENSE of displacement signal of output Y direction _Y1N3, SENSE _Y1Q10, SENSE _Y2N7 and SENSE _Y2Q6.The model with low-angle displacement according to Fig. 5 sets up can draw the output signal of respectively organizing sensing capacitance electrode group:

$X_{1N}=C\left(\mathrm{\θ}\right)\·\cos \left[2\mathrm{\π}\frac{(X_{\mathrm{NORMINAL}}+X_{\mathrm{\θ}})}{P}\right]$

$X_{1Q}=C\left(\mathrm{\θ}\right)\·\sin \left[2\mathrm{\π}\frac{(X_{\mathrm{NORMINAL}}-X_{\mathrm{\θ}})}{P}\right]$

$X_{2N}=C\left(\mathrm{\θ}\right)\·\cos \left[2\mathrm{\π}\frac{(X_{\mathrm{NORMINAL}}-X_{\mathrm{\θ}})}{P}\right]$

$X_{2Q}=C\left(\mathrm{\θ}\right)\·\sin \left[2\mathrm{\π}\frac{(X_{\mathrm{NORMINAL}}+X_{\mathrm{\θ}})}{P}\right]---\left(3\right)$

$Y_{1N}=C\left(\mathrm{\θ}\right)\·\cos \left[2\mathrm{\π}\frac{(Y_{\mathrm{NORMINAL}}+Y_{\mathrm{\θ}})}{P}\right]$

$Y_{1Q}=C\left(\mathrm{\θ}\right)\·\sin \left[2\mathrm{\π}\frac{(Y_{\mathrm{NORMINAL}}-Y_{\mathrm{\θ}})}{P}\right]$

$Y_{2N}=C\left(\mathrm{\θ}\right)\·\cos \left[2\mathrm{\π}\frac{(Y_{\mathrm{NORMINAL}}+Y_{\mathrm{\θ}})}{P}\right]$

$Y_{2Q}=C\left(\mathrm{\θ}\right)\·\sin \left[2\mathrm{\π}\frac{(Y_{\mathrm{MORMINAL}}-Y_{\mathrm{\θ}})}{P}\right]$

X wherein _θThe biasing displacement X that the deflection at finger θ angle produces X-direction sensing capacitance electrode group along X-direction _θ

Described X-Y-θ displacement direct decoupling measuring method based on planar capacitance sensor is passed through eight sensing capacitance electrode group output signals on the mobile pole plate 1 are adopted the operational method of " with the difference eliminate indigestion ", full decoupled low-angle displacement obtains the numerical value of low-angle displacement simultaneously in real time to the influence of X-axis and Y-axis displacement measurement.

$X_{\mathrm{NORMINAL}}=\frac{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HSA00000019122000011.png"\; state="\{\{state\}\}">P</figure-callout>}}{2\mathrm{\&pi;}}\arctan \frac{X_{1Q}+X_{2Q}}{X_{1N}+X_{2N}}$

$=\frac{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HSA00000019122000011.png"\; state="\{\{state\}\}">P</figure-callout>}}{2\mathrm{\&pi;}}\arctan \frac{C\left(\mathrm{\&theta;}\right)\&CenterDot;\sin \left[2\mathrm{\&pi;}\frac{(X_{\mathrm{NORMINAL}}-X_{\mathrm{\&theta;}})}{P}\right]+C\left(\mathrm{\&theta;}\right)\&CenterDot;\sin \left[2\mathrm{\&pi;}\frac{(X_{\mathrm{NORMINAL}}+X_{\mathrm{\&theta;}})}{P}\right]}{C\left(\mathrm{\&theta;}\right)\&CenterDot;\cos \left[2\mathrm{\&pi;}\frac{(X_{\mathrm{NORMINAL}}+X_{\mathrm{\&theta;}})}{P}\right]+C\left(\mathrm{\&theta;}\right)\&CenterDot;\cos \left[2\mathrm{\&pi;}\frac{(X_{\mathrm{NORMINAL}}-X_{\mathrm{\&theta;}})}{P}\right]}---\left(4\right)$

$=\frac{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HSA00000019122000011.png"\; state="\{\{state\}\}">P</figure-callout>}}{2\mathrm{\&pi;}}\arctan \left[\frac{\sin \left(2\mathrm{\&pi;}\frac{X_{\mathrm{NORMINAL}}}{P}\right)}{\cos \left(2\mathrm{\&pi;}\frac{X_{\mathrm{NORMINAL}}}{P}\right)}\right]=\frac{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HSA00000019122000011.png"\; state="\{\{state\}\}">P</figure-callout>}}{2\mathrm{\&pi;}}\arctan \left[\tan \left(2\mathrm{\&pi;}\frac{X_{\mathrm{NORMINAL}}}{P}\right)\right]$

$=X_{\mathrm{NORMINAL}}$

In like manner, can obtain

$Y_{\mathrm{NORMINAL}}=\frac{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HSA00000019122000011.png"\; state="\{\{state\}\}">P</figure-callout>}}{2\mathrm{\&pi;}}\arctan \frac{Y_{1Q}+Y_{2Q}}{Y_{1N}+Y_{2N}}---\left(5\right)$

$X_{\mathrm{\&theta;}}=Y_{\mathrm{\&theta;}}=\frac{1}{2}[\arctan \left(\frac{X_{2Q}}{X_{1N}}\right)-\arctan \left(\frac{X_{1Q}}{X_{2N}}\right)]---\left(6\right)$

$=\frac{1}{2}[-\arctan \left(\frac{Y_{2Q}}{Y_{1N}}\right)+\arctan \left(\frac{Y_{1Q}}{Y_{2N}}\right)]$

The analysis of through type (4)～formula (6), in-plane displancement signal X as can be seen _NOMINAL, Y _NOMINALDisplacement signal X with low-angle displacement correspondence _θ, Y _θRealized full decoupledly, this has just verified that the X-Y-θ displacement direct decoupling measuring method based on plane capacitance is fully feasible.

Measurement mechanism structure of the present invention and computational algorithm are simple.

Claims (5)

1. X-Y-θ displacement direct decoupling measuring device based on plane capacitance is characterized in that: measurement mechanism comprises a fixed polar plate (1) and places a mobile pole plate (2) of fixed polar plate top abreast; Fixed polar plate (1) upper surface is distributed with the capacitance electrode group that four groups of square symmetry distribute, every group of capacitance electrode group all be by wait size, equidistant, etc. the square capacitance electrode unit of number constitute; Mobile pole plate (2) lower surface be distributed with fixed polar plate on capacitance electrode group four groups of totally eight sensing capacitance electrode groups one to one, comprise four sensing electrode group SENSE of output X-axis displacement signal _X1N, SENSE _X1Q, SENSE _X2N, SENSE _X2QAnd four sensing electrode group SENSE of output Y-axis displacement signal _Y1N, SENSE _Y1Q, SENSE _Y2NAnd SENSE _Y2Q, SENSE wherein _X1N, SENSE _X1QBe one group, SENSE _X2N, SENSE _X2QBe one group, SENSE _Y1N, SENSE _Y1QBe one group, SENSE _Y2N, SENSE _Y2QBe last group; There is the alternate position spike in 1/4 cycle in two sensing capacitance electrode groups of each group at the initial position of corresponding direction of measurement, make output signal that 90 ° phase differential be arranged, sensing electrode group SENSE _X1N, SENSE _X2N, SENSE _Y1NAnd SENSE _Y2NThe output cosine signal, sensing electrode group SENSE _X1Q, SENSE _X2Q, SENSE _Y1QAnd SENSE _Y2QThe output sinusoidal signal.

2. a kind of X-Y-θ displacement direct decoupling measuring device according to claim 1 based on plane capacitance, it is characterized in that: eight sensing capacitance electrode groups on the described mobile pole plate (1), all comprise two groups of totally six capacitance electrode unit separately, capacitance electrode unit on the mobile pole plate is identical with capacitance electrode cell size on the fixed polar plate, when wherein one group the capacitance electrode unit in totally three capacitance electrode unit and the fixed polar plate fully over against the time, another group totally three capacitance electrode unit just in time with fixed polar plate in the capacitance electrode unit stagger fully, not over against area.

3. by a kind of X-Y-θ displacement direct decoupling measuring method based on plane capacitance of the described device of claim 1, it is characterized in that: the mobile pole plate of plane capacitance places the fixed polar plate top abreast; Be distributed with the capacitance electrode group that four groups of square symmetry distribute on the fixed polar plate, every group of capacitance electrode group all be by wait size, equidistant, etc. the square capacitance electrode unit of number constitute; Be distributed with on the mobile pole plate with fixed polar plate on capacitance electrode group four groups of totally eight sensing capacitance electrode groups one to one, there is the alternate position spike in 1/4 cycle in two sensing capacitance electrode groups of each group at the initial position of corresponding direction of measurement, make output signal that 90 ° phase differential be arranged; Simultaneously, eight sensing capacitance electrode groups, all comprise two groups of totally six capacitance electrode unit separately, when wherein one group the capacitance electrode unit in totally three capacitance electrode unit and the fixed polar plate fully over against the time, another group totally three capacitance electrode unit just in time with fixed polar plate in the capacitance electrode unit stagger fully, not over against area; This has just guaranteed the SENSE of output X-axis displacement signal _X1N, SENSE _X1Q, SENSE _X2N, SENSE _X2QSENSE with the displacement signal of exporting Y direction _Y1N, SENSE _Y1Q, SENSE _Y2N, SENSE _Y2QAll only reflect the change in displacement of direction of measurement separately, and can not be subjected to the influence of non-direction of measurement top offset, realized that the direct decoupling of X-axis and Y-axis displacement is measured; When mobile pole plate relative fixed pole plate produces in-plane displancement, eight sensing capacitance electrode groups will produce eight electric capacity output signals, by with difference eliminate indigestion computing, but there be the X-axis Y-axis in-plane displancement output signal of low-angle displacement under disturbing in direct decoupling, and draws this low-angle displacement signal θ.

4. a kind of X-Y-θ displacement direct decoupling measuring method based on plane capacitance according to claim 3 is characterized in that: 1) when the mobile pole plate of planar capacitance sensor when X-direction produces displacement with respect to fixed polar plate, sensing capacitance electrode group SENSE _X1NAnd SENSE _X2NOutput cosine curve signal, sensing capacitance electrode group SENSE _X1QAnd SENSE _X2Q1/4 cycle of backwardness output sinusoidal signal, SENSE _Y1N, SENSE _Y1Q, SENSE _Y2NAnd SENSE _Y2QSignal does not change; 2) when the mobile pole plate of planar capacitance sensor when Y direction produces displacement with respect to fixed polar plate, sensing capacitance electrode group SENSE _Y1NAnd SENSE _Y2NOutput cosine curve signal, sensing capacitance electrode group SENSE _Y1QAnd SENSE _Y2Q1/4 cycle of backwardness output sinusoidal signal, SENSE _X1N, SENSE _X1Q, SENSE _X2NAnd SENSE _X2QSignal does not change.

5. a kind of X-Y-θ displacement direct decoupling measuring method according to claim 3 based on plane capacitance, it is characterized in that: when there was a less deflection angular displacement in mobile pole plate, θ＜1 ° generally was when with clockwise deflection θ angle, on X-direction, will make SENSE _X1NAnd SENSE _X2QOutput signal have an X _θThe phase place of/P is leading, SENSE _X1QAnd SENSE _X2NOutput signal an X is then arranged _θ/ P phase lag; On the Y direction, SENSE _Y1NAnd SENSE _Y2QOutput signal have a Y _θThe phase place of/P is leading, SENSE _Y1QAnd SENSE _Y2NOutput signal a Y is then arranged _θ/ P phase lag, described X-Y-θ displacement direct decoupling measuring method based on plane capacitance is passed through the operational method of " with the difference eliminate indigestion ", full decoupled low-angle displacement signal obtains the numerical value of low-angle displacement θ simultaneously in real time to the influence of X-axis and Y-axis displacement measurement; In the formula: X _θThe biasing displacement that the deflection at finger θ angle produces X-direction sensing capacitance electrode group along X-direction; Y _θThe biasing displacement that the deflection at finger θ angle produces Y direction sensing capacitance electrode group along Y direction; P refers to the adjacent spacing of sensing capacitance electrode on direction of measurement.

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