CN104567653A - Method for measuring angle of inner frame of multi-frame pod by electric eddy-current transducer - Google Patents

Abstract

The invention discloses a method for measuring an angle of an inner frame of a multi-frame pod by an electric eddy-current transducer. The method comprises steps as follows: the electric eddy-current transducer and an induction steel disc are installed on a to-be-measured inner frame and an installation frame of the inner frame respectively; when the to-be-measured inner frame rotates relative to the installation frame, the distance between the electric eddy-current transducer and the induction steel disc is changed, and the electric eddy-current transducer outputs a voltage signal V related with distance change; the voltage signal output by the electric eddy-current transducer is subjected to filter and analog-digital conversion, and meanwhile, the distance h between the electric eddy-current transducer and the induction steel disc is calculated according to a scaling factor of the electric eddy-current transducer and an amplification coefficient of analog-digital conversion; the angle between the to-be-measured inner frame and the installation frame of the inner frame is calculated according to the distance h between the electric eddy-current transducer and the induction steel disc. The size and the weight of a multi-frame pod system can be reduced, the friction force can be reduced, and high-precision angle measurement can be realized.

Description

A kind of method of electric vortex sensor measuring many frameworks gondola inner frame angle

Technical field

The present invention relates to a kind of method of electric vortex sensor measuring many frameworks gondola inner frame angle, belong to many frameworks gondola control technology field.

Background technology

Photoelectric nacelle keeps its inside panel stable in motion process with rate stabilization principle, utilize load on platform (can by light video camera, thermal infrared imager, airborne laser range finder etc.) to obtain the information such as image, distance of target, complete the identification of target, follow the tracks of and locate.The fields such as Aerial photography, military surveillance, border patrols, searching rescue, safety law enforcement are widely used according to the outfit of load.The performance of photoelectric nacelle is mainly reflected in infrared, the detection range of visible ray and the range capability of laser instrument.These performances load self meet condition under, then determined by the lasting accuracy of photoelectric nacelle.At present, the lasting accuracy of external photoelectric nacelle can reach 3 differential of the arcs (be equivalent to 1 km target far away and only rock 3 millimeters), and corresponding range capability can reach 30 kms.And the lasting accuracy of domestic photoelectric nacelle is 25 differential of the arcs, range capability is 15 kms, and gap is larger.

Many frameworks photoelectric nacelle is the dominant form of electro-optical pod, refers to and utilizes inside and outside two-layer frame stability to same axle: outside framework resists windage, elementary vibration damping; Inner frame realizes higher lasting accuracy.When outside framework is identical, the lasting accuracy of inner frame determines the lasting accuracy of whole many frameworks photoelectric nacelle.Current many frameworks photoelectric nacelle inner frame both domestic and external all utilizes scrambler or rotary transformer device to take measurement of an angle.First, inner frame angle is little, be generally less than ± 3 °.And scrambler or rotary transformer are all-round measuring element, so the waste on volume, weight and range can be brought when utilizing above-mentioned device angle measurement.Secondly, all need corresponding axle head to support when scrambler and rotary transformer application, can friction be introduced, and friction force is the principal element affecting platform stable precision.A kind of many frameworks gondola inner frame angle high-precision measuring method that can reduce friction of current urgent need.

Summary of the invention

The technology of the present invention is dealt with problems and is: for the deficiencies in the prior art, provide a kind of method of electric vortex sensor measuring many frameworks gondola inner frame angle, by adopting current vortex sensor and accurate computing in the inner frame of many frameworks photoelectric nacelle, obtain high-precision many frameworks gondola angle measurement.

Technical solution of the present invention:

A kind of method of electric vortex sensor measuring many frameworks gondola inner frame angle:

Current vortex sensor and induction steel disc are installed on the installation frame of inner frame to be measured and this inner frame respectively;

When inner frame to be measured rotates relative to its installation frame, current vortex sensor changes relative to the distance of induction steel disc, and current vortex sensor exports and changes relevant voltage signal V to distance;

The voltage signal that current vortex sensor exports, by filtering and analog to digital conversion, simultaneously calculates current vortex sensor and induction steel disc distance h according to the scale factor of current vortex sensor and analog-to-digital amplification coefficient;

According to the distance h of current vortex sensor and induction steel disc, the angle between the installation frame calculating inner frame to be measured and this inner frame.

The installation site of described current vortex sensor is R apart from the length in the axle center of inner frame to be measured ₁, described R ₁for wherein L ₁for the range of current vortex sensor, θ are the required angular range, the described R that measure ₁under meeting the prerequisite of inequality, R ₁value should be as far as possible close

Described calculating current vortex sensor and induction steel disc distance wherein, k ₁represent the scale factor of current vortex sensor, n represents analog-to-digital figure place, and η represents analog-to-digital input voltage range.

The described distance h according to current vortex sensor and induction steel disc, the specific implementation of the angle beta between the installation frame calculating inner frame to be measured and this inner frame is as follows:

(4a) the angle α of the induction straight line at steel disc place and the axle center of inner frame to be measured and steel disc line is calculated:

$\mathrm{\α}=\arcsin \left(\frac{0.5L_1+L_3}{R_1}\right)$

Wherein, L ₃represent that current vortex sensor distance perspective answers the minor increment of steel disc;

(4b) the angle α and distance h that obtain in step (4a) is utilized, the angle beta between the installation frame calculating inner frame to be measured and this inner frame:

$\mathrm{\β}=\mathrm{arc}\cos \left(\frac{\sqrt{1-c^2+2c\tan \mathrm{\α}}-c\tan \mathrm{\α}+{\tan }^2\mathrm{\α}}{1+{\tan }^2\mathrm{\β}}\right)$

Wherein, $c=\frac{h\sqrt{1+{\tan }^2\mathrm{\α}}}{R_1}.$

Angle beta between described inner frame to be measured and the installation frame of this inner frame, when measuring accuracy requires lower, formula of reduction can be utilized to calculate, and formula of reduction is:

Described induction steel disc and the installation site of current vortex sensor can exchange, and are installed on the installation frame of inner frame to be measured and this inner frame respectively, the angle of the installation frame of inner frame to be measured and this inner frame ${\mathrm{\β}}_1=\arccos \left(\frac{\sqrt{1-{c_1}^2+2c_1\tan {\mathrm{\α}}_1}-c_1\tan {\mathrm{\α}}_1+{\tan }^2{\mathrm{\α}}_1}{1+{\tan }^2{\mathrm{\α}}_1}\right),$ Wherein α ₁for the angle of the straight line at current vortex sensor place and the axle center of inner frame to be measured and current vortex sensor line;

The present invention is relative to the beneficial effect of prior art:

(1) means such as the present invention by adopting electric vortex sensor measuring angle in the inner frame of many frameworks photoelectric nacelle, the scrambler of the equal size adopted relative to prior art, can improve the inner frame angle-measurement accuracy of many frameworks gondola significantly.

(2) the present invention is relative to prior art, the current vortex sensor adopted without the need to installing turning axle separately, decrease between centers friction, improve many frameworks photoelectric nacelle lasting accuracy, reduce the volume of inner frame, weight simultaneously.

(3) the present invention sets up the coordinate system of current vortex sensor and induction steel disc, calculated by the position mathematical model and strict data of setting up two, solve the position relationship of current vortex sensor and induction steel disc, and then solve inner frame angle, improve the measuring accuracy of inner frame angle, improve the performance of many frameworks pod control system.

Accompanying drawing explanation

Fig. 1 is current vortex sensor of the present invention and induction steel disc composition schematic diagram;

Fig. 2 is the present invention's many frameworks gondola bearing wall and frame structure schematic layout pattern;

Fig. 3 is the position relationship schematic diagram of current vortex sensor of the present invention and induction steel disc and pitching frame;

Fig. 4 is that the present invention is along pitch axis direction current vortex sensor and the relative position relation schematic diagram responding to steel disc;

Fig. 5 is the angle calculation schematic diagram between the installation frame of the present invention's inner frame to be measured and this inner frame;

Fig. 6 is the numerical value corresponding relation figure of accurate angle of the present invention and rough angle and ADC value;

Fig. 7 is the numerical value corresponding relation figure of angle difference that the present invention is accurate and rough and ADC value.

Embodiment

Below in conjunction with accompanying drawing, principle of work of the present invention and the course of work are further explained and are illustrated.

As shown in Figure 1, current vortex sensor and induction steel disc are applied in the inner frame angle measuring system design of many frameworks photoelectric nacelle, to improve angle-measurement accuracy by the present invention.Wherein, current vortex sensor is direct current supply, and the optional+24V of voltage or ± 15V, output voltage is chosen as-2--18V or 0-5V.Induction steel disc material requires to be No. 45 steel.L in the range ability of current vortex sensor ₁, output voltage and current vortex sensor and induction steel disc spacing proportional, if scale-up factor is k ₁.Current vortex sensor can to slight distance high-acruracy survey (can reach micron level), so the feature little according to inner frame slewing area, the distance the caused change utilizing electric vortex sensor measuring to rotate, then obtains rotational angle according to the relation of this Distance geometry radius of gyration.

As shown in Figure 2, the azimuth axis of many frameworks gondola and pitch axis all adopt inside and outside two-layer Frame Design, so inner frame comprises orientation framework and pitching frame.

As shown in Figure 3, current vortex sensor and induction steel disc are installed on the installation frame of inner frame to be measured and this inner frame respectively.

The installation site of current vortex sensor:

As shown in Figure 4, current vortex sensor and the detail location responding to steel disc in the present invention.Current vortex sensor high order end position is A ₁, induction steel disc position is B.The linear measurement range of current vortex sensor is at A ₁and A ₃between, string A ₁a ₃length is L ₁.OA ₂perpendicular to A ₁a ₃, intersection point is O '.When current vortex sensor is positioned at A ₂time, its surface is just right with induction steel disc.Current vortex sensor distance perspective answers the some A of the minor increment of steel disc ₃distance induction steel disc spacing is L ₃(because current vortex sensor is in consistent change, so the position of distance steel disc is also in real-time change), general L ₃≈ 1mm.

The range Theta that takes measurement of an angle is determined by inner frame design requirement, is generally less than ± 3 ° (or 6 °); Current vortex sensor linear measurement range L ₁product attribute, generally at 6mm.The measured value of current vortex sensor is from a nonzero value, and namely measured value is 1 to 7 millimeters.

The installation site of current vortex sensor is R apart from the length in the axle center of inner frame to be measured ₁, described R ₁for wherein L ₁for the range of current vortex sensor, θ are the required angular range measured, described R ₁under meeting the prerequisite of inequality, R ₁value should be as far as possible close

In the installation process of current vortex sensor and induction steel disc, concrete structural condition be considered, the size of such as pitch axis, whether with other device interference etc.R ₁value is as far as possible large, because under the condition determined in current vortex sensor distance accuracy, radius is larger, and angle-measurement accuracy is higher.

When inner frame to be measured rotates relative to its installation frame, current vortex sensor changes relative to the distance of induction steel disc, and current vortex sensor exports and changes relevant voltage signal V to distance;

The voltage signal that current vortex sensor exports, by filtering and analog to digital conversion, simultaneously according to scale factor and the analog-to-digital amplification coefficient of current vortex sensor, calculates current vortex sensor and induction steel disc distance h; In the present invention, current vortex sensor is exactly the distance of current vortex sensor probe plane center point P to steel disc to the distance h of induction steel disc, calculates according to measured value wherein k ₁represent the scale factor of current vortex sensor, n represents analog-to-digital figure place, and η represents analog-to-digital input voltage range.

According to the distance h of current vortex sensor and induction steel disc, the angle between the installation frame calculating inner frame to be measured and this inner frame.

According to the distance h of current vortex sensor and induction steel disc, the specific implementation of the angle beta between the installation frame calculating inner frame to be measured and this inner frame is as follows:

As shown in Figure 5, being X-axis with OB, is that initial point sets up rectangular coordinate system xOy with O.OB=R ₁, straight line l represented the straight line on steel disc surface, and α is the angle of the induction straight line at steel disc place and the axle center of inner frame to be measured and steel disc line.

$\mathrm{\α}=\arcsin \left(\frac{0.5L_1+L_3}{R_1}\right).$

The equation of the straight line l at induction steel disc place is

y＝tanα(x-R ₁)。

Point P is taking round dot as the center of circle, and radius is R ₁, polar angle from arrive circular arc on.The coordinate of some P is,

$\left\{\begin{array}{c}x=R_1\cos \mathrm{\β}\\ y=R_1\sin \mathrm{\β}\end{array}\right.,$

Wherein, visible, the framework angle beta of actual measurement is larger than the frame corners range Theta of requirement.

So according to mathematical relation, the distance of some P to straight line l is

$h=\frac{R_1\sin \mathrm{\β}-R_1\cos \mathrm{\β}\tan \mathrm{\α}+R_1\tan \mathrm{\α}}{\sqrt{1+{\tan }^2\mathrm{\α}}}.$

Wherein, R ₁, α is known, $h=\frac{\mathrm{V\η}}{k_1{2}^n},$ Solving equation $h=\frac{R_1\sin \mathrm{\β}-R_1\cos \mathrm{\β}\tan \mathrm{\α}+R_1\tan \mathrm{\α}}{\sqrt{1+{\tan }^2\mathrm{\α}}},$ β can be calculated.

Concrete solution procedure is as follows

According to formula $h=\frac{R_1\sin \mathrm{\β}-R_1\cos \mathrm{\β}\tan \mathrm{\α}+R_1\tan \mathrm{\α}}{\sqrt{1+{\tan }^2\mathrm{\α}}}$ Obtain following formula:

$\sin \mathrm{\β}=\frac{h\sqrt{1+{\tan }^2\mathrm{\α}}}{R_1}+\cos \mathrm{\β}\tan \mathrm{\α}-\tan \mathrm{\α}$

And in conjunction with sin ²β+cos ²β=1, can obtain,

(1+tan ²α)cos ²β+2atanαcosβ+a ²-1＝0

Wherein, $\left\{\begin{array}{c}c=\frac{h\sqrt{1+{\tan }^2\mathrm{\α}}}{R_1}\\ a=c-\tan \mathrm{\α}\end{array}\right.;$

Because 0≤cos β≤1, so

$\cos \mathrm{\β}=\frac{\sqrt{1-c^2+2c\tan \mathrm{\α}}-c\tan \mathrm{\α}+{\tan }^2\mathrm{\α}}{1+{\tan }^2\mathrm{\α}},$

Then,

$\mathrm{\β}=\mathrm{arc}\cos \left(\frac{\sqrt{1-c^2+2c\tan \mathrm{\α}}-c\tan \mathrm{\α}+{\tan }^2\mathrm{\α}}{1+{\tan }^2\mathrm{\β}}\right).$

When precise requirements is not high, because α is very little, tan α ≈ 0 can be thought, according to formula $\cos \mathrm{\β}=\frac{\sqrt{1-c^2+2c\tan \mathrm{\α}}-c\tan \mathrm{\α}+{\tan }^2\mathrm{\α}}{1+{\tan }^2\mathrm{\α}}$ Can obtain,

${\cos }^2\mathrm{\β}+{\left(\frac{h}{R_1}\right)}^2=1$

So, because β is also very little, can think

$\mathrm{\β}\≈\frac{h}{R_1}.$

The installation site of induction steel disc and current vortex sensor can exchange, and is installed on the installation frame of inner frame to be measured and this inner frame respectively, the angle of the installation frame of inner frame to be measured and this inner frame ${\mathrm{\β}}_1=\arccos \left(\frac{\sqrt{1-{c_1}^2+2c_1\tan {\mathrm{\α}}_1}-c_1\tan {\mathrm{\α}}_1+{\tan }^2{\mathrm{\α}}_1}{1+{\tan }^2{\mathrm{\α}}_1}\right),$ Wherein α ₁for the angle of the straight line at current vortex sensor place and the axle center of inner frame to be measured and current vortex sensor line;

With a specific embodiment, the course of work of the present invention is explained further below:

As shown in Figure 3 and Figure 4, O is the rotation axis of pitching frame, and the radius of clean-up of current vortex sensor is R ₁.Select to get θ=6 ° here, L ₁=6mm.So, select R ₁for 55mm.

The minimum distance L of current vortex sensor and steel disc ₃=1mm.

According to formula $\mathrm{\α}=\arcsin \left(\frac{0.5L_1+L_3}{R_1}\right),$ Calculate α=4.17 °.

Current vortex sensor is energized, and its output signal, after a simulation low-pass filter, utilizes analog to digital converter to be converted to digital signal.If analog to digital converter input voltage range is 0-5V, change figure place into 16, then the amplification coefficient of analog to digital converter is k _d=13107.The scale factor k of current vortex sensor ₁=0.83V/mm.Current vortex sensor distance accuracy is 5 microns, so its angle measurement accuracy is about 0.0052 °.

The conversion value of microcomputer reads analog to digital converter is μ ∈ [0,65535], then current vortex sensor and steel disc spacing so the high pitching frame angle of accuracy requirement is according to formula

$\mathrm{\β}=\mathrm{arc}\cos \left(\frac{\sqrt{1-c^2+2c\tan \mathrm{\α}}-c\tan \mathrm{\α}+{\tan }^2\mathrm{\α}}{1+{\tan }^2\mathrm{\β}}\right)$ Calculate, the low pitching frame angle of accuracy requirement is according to formula calculate.

Fig. 6 gives exact value and the coarse value relation relative to ADC value, and Fig. 7 gives difference between the two.Visible, both differences are maximum reaches 0.46mrad or 0.026 °.So application person can according to the demand of degree of accuracy being selected to this two formula.

The unexposed part of the present invention is the open general knowledge in this area.

Claims (6)

1., by a method for electric vortex sensor measuring many frameworks gondola inner frame angle, it is characterized in that:

Current vortex sensor and induction steel disc are installed on the installation frame of inner frame to be measured and this inner frame respectively;

When inner frame to be measured rotates relative to its installation frame, current vortex sensor changes relative to the distance of induction steel disc, and current vortex sensor exports and changes relevant voltage signal V to distance;

The voltage signal that current vortex sensor exports, by filtering and analog to digital conversion, simultaneously calculates current vortex sensor and induction steel disc distance h according to the scale factor of current vortex sensor and analog-to-digital amplification coefficient;

According to the distance h of current vortex sensor and induction steel disc, the angle between the installation frame calculating inner frame to be measured and this inner frame.

2. the method for a kind of electric vortex sensor measuring many frameworks gondola inner frame angle according to claim 1, is characterized in that: the installation site of described current vortex sensor is R apart from the length in the axle center of inner frame to be measured ₁, described R ₁for wherein L ₁for the range of current vortex sensor, θ are the required angular range measured, described R ₁under meeting the prerequisite of inequality, R ₁value should be as far as possible close

3. the method for a kind of electric vortex sensor measuring many frameworks gondola inner frame angle according to claim 2, is characterized in that: described calculating current vortex sensor and induction steel disc distance wherein, k ₁represent the scale factor of current vortex sensor, n represents analog-to-digital figure place, and η represents analog-to-digital input voltage range.

4. the method for a kind of electric vortex sensor measuring many frameworks gondola inner frame angle according to claim 3, it is characterized in that: the described distance h according to current vortex sensor and induction steel disc, the specific implementation of the angle beta between the installation frame calculating inner frame to be measured and this inner frame is as follows:

(4a) the angle α of the induction straight line at steel disc place and the axle center of inner frame to be measured and steel disc line is calculated:

$\mathrm{\α}=\mathrm{arcisn}\left(\frac{0.5L_1+L_3}{R_1}\right)$

Wherein, L ₃represent that current vortex sensor distance perspective answers the minor increment of steel disc;

(4b) the angle α and distance h that obtain in step (4a) is utilized, the angle beta between the installation frame calculating inner frame to be measured and this inner frame:

$\mathrm{\β}=\arccos \left(\frac{\sqrt{1-c^2+2c\tan \mathrm{\α}}-c\tan \mathrm{\α}+{\tan }^2\mathrm{\α}}{1+{\tan }^2\mathrm{\α}}\right)$

Wherein, $c=\frac{h\sqrt{1+{\tan }^2\mathrm{\α}}}{R_1}.$

5. the method for a kind of electric vortex sensor measuring many frameworks gondola inner frame angle according to claim 4, it is characterized in that: the angle beta between described inner frame to be measured and the installation frame of this inner frame, when measuring accuracy requires lower, formula of reduction can be utilized to calculate, and formula of reduction is:

6. the method for a kind of electric vortex sensor measuring many frameworks gondola inner frame angle according to claim 5, it is characterized in that: described induction steel disc and the installation site of current vortex sensor can exchange, be installed on the installation frame of inner frame to be measured and this inner frame respectively, the angle of the installation frame of inner frame to be measured and this inner frame ${\mathrm{\β}}_1=\arccos \left(\frac{\sqrt{1-{c_1}^2+2c_1\tan {\mathrm{\α}}_1}-c_1\tan {\mathrm{\α}}_1+{\tan }^2{\mathrm{\α}}_1}{1+{\tan }^2{\mathrm{\α}}_1}\right),$ Wherein α ₁for the angle of the straight line at current vortex sensor place and the axle center of inner frame to be measured and current vortex sensor line; $c_1=\frac{h\sqrt{1+{\tan }^2{\mathrm{\α}}_1}}{R_1}.$