CN1089160C - Method for three dimension position measurement using miniature inertia measurement combination - Google Patents

Abstract

The present invention belongs to the technical field of precise measurement. The present invention comprises a measuring device composed of a three-dimensional position calibrating measuring head and a computer system, wherein a miniature inertia measuring combiner composed of six micro-sensors is hermetically installed in the measuring head of which the lower end is a measuring probe. The probe is firstly used for aligning to a measuring basic point P0 and then aligning to a measured point P1, and the rotating angular speeds and the acceleration of three shafts of the measuring head are output by a sensor; the computer system obtains the three-dimensional position of the point P1 relatively to the basic point P0 by processing data. The present invention can satisfy requirements for large-sized three-dimensional measurement, and the measuring system of the present invention has the advantages of high reliability, low cost, convenient operation, etc.

Description

A kind of method of three dimension position measurement using miniature inertia measurement combination

The invention belongs to the precise measurement technique field, particularly the application technology of MIMU (Micro Inertial Measurement Unit).

In commercial production and scientific experiment, usually need to carry out three-dimensional position measuring, as the processing of workpiece, accurate installation of part or the like.For miniature workpiece, just can finish the measurement of three-dimensional position with general survey instrument, but to large-scale workpiece, common measuring method is often unworkable.For example, in the manufacturing of aircraft wing, need to demarcate the position of each point on the wing, long tens meters of the wing of aircraft has complicated curved-surface structure, calibrates exactly with general survey instrument and measuring method that the three-dimensional position of each point is a very difficult thing on the wing.The method of laser ranging can accurately be finished the measurement of big distance, but this method only is applicable to the one dimension orientation measurement, can't satisfy the needs of three-dimensional measurement.External solution to this problem is a three coordinate measuring machine, and by years of researches, develops into computer numerical control (CNC) three coordinate measuring machine by the mechanical type three coordinate measuring machine.Comparatively successful application is that under the control of a measurement centre, the three coordinate measuring machine of four Zeiss companies is combined in the MTU of Germany turbine engine manufacturing plant, has born the metering of 28 kinds of complicated precision components of whole automated workshop production.Yet, its outstanding shortcoming be bulky, equipment is complicated, cost is too high, therefore be not suitable for applying.

The objective of the invention is to for overcoming the weak point of said method, a kind of brand-new three-dimensional position measuring method has been proposed, satisfy the needs of large scale three-dimensional measurement, the three-dimensional position measuring system that is designed by this method has advantages such as reliability height, cost be low, easy to operate.

The present invention proposes a kind of method of three dimension position measurement using miniature inertia measurement combination, it is characterized in that, comprises by three-dimensional position calibration measurements head and computer system composition measuring apparatus; Encapsulation MIMU (Micro Inertial Measurement Unit) in the said three-dimensional position calibration measurements head, MIMU (Micro Inertial Measurement Unit) is made up of six microsensors, and the lower end of this measuring head is a measuring probe; Concrete measuring process is as follows:

1) earlier measure basic point P0 with probe alignment, the traverse measurement head is with measured some P1 of probe alignment then, and gyroscope is responsive and export the angle of rotation speed of three axles of measuring head, and accelerometer sensitive is also exported three axial acceleration of measuring head;

2) computer system obtains the three-dimensional position of the relative basic point P0 of P1 point by the output of data line sampling sensor by data processing;

3) computer system obtains the three-dimensional position of the relative basic point P0 of P1 point by the output of data line sampling sensor by data processing:

4) measure the P1 point after, basic point P0 is retracted and aimed to measuring head, computer initialization, the traverse measurement head is aimed at next measurement point P2 again, the data processing of computer repeats processing obtains the position that P2 is ordered, can finish the demarcation of the three-dimensional position of a plurality of measurement points on the arbitrary surface by that analogy, its result is outputed on the display by computing machine.Said computer data is handled and can be may further comprise the steps;

1) extracts the angular velocity signal that little gyro is exported with second order angular velocity, the acceleration signal of the micro-acceleration gauge of sampling simultaneously output;

2) signal to little gyro and micro-acceleration gauge output carries out closed loop error compensation;

3) employing is obtained the attitude angle of measuring head coordinate system through the data of error compensation with fourth-order Runge-Kutta method by the hypercomplex number differential equation;

4) acceleration signal along measuring head coordinate system direction is resolved into along the component of acceleration of geographic coordinate system direction;

5) three components to the acceleration in the geographic coordinate system carry out numerical integration twice, obtain the movement velocity and the three-dimensional position of measuring head respectively.

Measuring principle of the present invention is as follows:

The theoretical foundation of this method is the strapdown inertial navigation principle.The core component of inertial navigation system is the inertia measurement combination, and it is made of inertial acceleration meter and gyro.Common inertia measurement combined volume is huge, weight is big, can only be used for the navigation on aircraft, naval vessel.The working environment of using according to the present invention draws it and has different applicable elements with strapdown inertial navigation system, thereby adopted the measuring method different with strapdown inertial navigation system:

One, the present invention select for use by the micro-acceleration gauge of micro-processing technology manufacturing and little gyro and constitute MIMU (Micro Inertial Measurement Unit), thereby measurement component one measuring head has little, the lightweight characteristics of volume, can finish three-dimensional position measuring easily.

Two, operating distance of the present invention is little, the time short.Operating distance of the present invention is several meters to tens meters, is several seconds to the Measuring Time of a point, is far smaller than the working range of strapdown inertial navigation system.Thereby the latitude that operating distance causes changes and can ignore, and this condition can make the error differential equation reduce to five by six.Because working time and the error that causes are the relations of quadratic sum cube, thereby, reduce Measuring Time and can improve measuring accuracy greatly.

Three, environmental interference of the present invention and noise are little.Inertia measurement combination in the strap-down inertial is fixed on the aircraft, and working sensor is in the environment of high-speed motion, dither, and random disturbance and noise are very big, and useful signal must could use by filtering.By contrast, it is just very little to be operated in sensor is subjected in the conventional environment interference and noise.

Four, the movement velocity of mini inertia measurement head, acceleration and rotational angular are little.The movement rate of this measuring head be 5m/s to 10m/s, acceleration is less than 2g, they are far smaller than the aircraft or the guided missile of inertial navigation, thereby error analysis is based on the quiet pedestal error of this system.In addition, because the measurement range of sensor reduces, make the scaling factor of sensor can obtain very little.

For reducing the error of inertial sensor output signal, the present invention has adopted closed loop error compensation.The error source of inertance element comprises: high-order errors such as the responsive error of the first power sum of errors quadratic power of the error of zero of sensor, dynamic error, alignment error, scale error, specific force.According to the analysis of front, only consider to cause than those of mistake, obtain following inertial sensor error model formula: $\mathrm{\Δ}{A}_x={\mathrm{\θ}}_{\mathrm{xz}}^a{A}_y-{\mathrm{\θ}}_{\mathrm{xy}}^a{A}_z+k{Q}_x{A}_x^2+\mathrm{\Δ}{A}_x^{\′}$ ${\mathrm{\ΔA}}_y={\mathrm{\θ}}_{\mathrm{yx}}^a{A}_z-{\mathrm{\θ}}_{\mathrm{yz}}^a{A}_x+k{Q}_y{A}_y^2+{\mathrm{\ΔA}}_y^{\′}----\left(1\right)$ ${\mathrm{\ΔA}}_z={\mathrm{\θ}}_{\mathrm{zy}}^a{A}_x-{\mathrm{\θ}}_{\mathrm{xz}}^a{A}_y+k{Q}_z{A}_z^2+{\mathrm{\ΔA}}_z^{\′}$ ${\mathrm{\ϵ}}_x={\mathrm{\θ}}_{\mathrm{xz}}^g{\mathrm{\ω}}_y-{\mathrm{\θ}}_{\mathrm{xy}}^g{\mathrm{\ω}}_z-m^1{A}_x-q^1{A}_y+n^1{A}_x{A}_z+{\mathrm{\ϵ}}_x^{\′}+C{\mathrm{\ω}}_x{\mathrm{\ω}}_z$ ${\mathrm{\ϵ}}_y={\mathrm{\θ}}_{\mathrm{yx}}^g{\mathrm{\ω}}_z-{\mathrm{\θ}}_{\mathrm{yz}}^g{\mathrm{\ω}}_x-m^1{A}_y+q^1{A}_x+n^1{A}_y{A}_z+{\mathrm{\ϵ}}_y^{\′}+C{\mathrm{\ω}}_z{\mathrm{\ω}}_y----\left(2\right)$ ${\mathrm{\ϵ}}_z={\mathrm{\θ}}_{\mathrm{zy}}^g{\mathrm{\ω}}_x-{\mathrm{\θ}}_{\mathrm{zx}}^g{\mathrm{\ω}}_y-m^2{A}_z+q^2{A}_y+n^2{A}_x{A}_z+{\mathrm{\ϵ}}_z^{\′}+C{\mathrm{\ω}}_x{\mathrm{\ω}}_z$ Δ A in the formula _i' (i=x, y z) are the error of zero of accelerometer, ε _i' be gyro drift rate; θ _Ij ^a, θ _Ij ^g(i, j=x, y z) are respectively the alignment error angle of accelerometer and gyro; KQ _iBe the acceleration quadratic term, m, q, n are relevant of acceleration; C is a gyro intersecting axle coupling coefficient.

According to formula (1), (2) inertial sensor is carried out closed loop error compensation.As shown in Figure 1 and Figure 2, because closed loop compensation is to obtain error compensation amount with the signal after compensating, the output of inertance element is compensated, so the output accuracy of this error compensating method is higher.Among Fig. 2, ε _Ax, ε _Ay, ε _AzBe expressed as follows respectively: ε _Ax=-m ¹A _x-q ¹A _y+ n ¹A _xA _Zzε _Ay=-m ¹A _y+ q ¹A _x+ n ¹A _yA _z(3) ε _Az=-m ²A _z+ q ²A _y+ n ²A _xA _zBy analysis, draw as drawing a conclusion: this method static error that input causes to constant acceleration can all compensate; The dynamic error that input causes to Constant Angular Velocity can compensate to less than 10 ^-7With magnitude.Error after the compensation is: Δ A _x=Δ A _y=Δ A ₂=10 ^-7G, ε _x=ε _y=ε _z=10 ^-6Rad/s, α ₀=β ₀=γ ₀=10 ^-5Rad.

Obtain error equation under the static pedestal according to front applicable elements analysis, it is five differential equation of first order groups, and its matrix form is as follows:

It is owing to can ignore in the variation of measuring middle latitude that the number of the differential equation is reduced to five by six, i.e. δ =0.Parameter is got earth radius R=6367.65km respectively in the following formula 1, rotational-angular velocity of the earth ω _e=15.04107 °/h, local (Beijing) latitude =39.933 °, local acceleration g=9.80065m/s ², measurement time t=3s.Find the solution (4) formula with fourth-order Runge-Kutta method, use the site error equation again: $\mathrm{\δ}\stackrel{\·}{Y}=-\mathrm{\δ}{V}_v----\left(5\right)$ $\mathrm{\δ}\stackrel{\·}{Z}=-\mathrm{\δ}{V}_z$ Obtain the three-dimensional measurement error of system, graph of errors as shown in Figure 3.The measuring error of this system is less than 1mm as can be seen, and corresponding measurement range is 20 meters, and this precision can satisfy the processing and manufacturing of general large-scale workpiece.

The present invention has following characteristics:

The first, this method at first is applied to precision measurement with the inertial navigation theory, in conjunction with the new results of micrometer/nanometer technology, has started a new application of MIMU (Micro Inertial Measurement Unit).The second, by theoretical analysis, confirm that this method has higher measuring accuracy.In the measurement range of 20m, measuring error is less than 1mm.

Three, the method for this three dimension position measurement using miniature inertia measurement combination of the present invention's proposition is applicable to the three-dimensional measurement and the location position of large complicated workpiece, the three-dimensional position measuring system that is designed by this method has advantages such as reliability height, cost be low, easy to operate, and measurement range can reach 5 meters to 20 meters.This method can be used for the processing and manufacturing of large-scale workpiece, as the manufacturing of heavy duty equipment, naval vessel, aerospace equipment and large-scale generating set, thereby has wide application market.

Brief Description Of Drawings Fig. 1 is an inertial acceleration meter closed loop error compensating method synoptic diagram of the present invention.Fig. 2 is an inertia gyroscope closed loop error compensating method synoptic diagram of the present invention.Fig. 3 is the site error curve synoptic diagram after the error compensation of the present invention.Fig. 4 is a three-dimensional position measuring device synoptic diagram of the present invention.Fig. 5 is a measuring head coordinate system synoptic diagram of the present invention.Fig. 6 is a three-dimensional position measuring method synoptic diagram of the present invention for three-dimensional position measuring device work synoptic diagram Fig. 7 of the present invention.

The present invention proposes a kind of three-dimensional position measuring device embodiment that makes up based on inertia measurement as shown in Figure 4 to 7, and it is as follows to describe measuring method in detail in conjunction with each figure:

Present embodiment is made up of three-dimensional position calibration measurements head and computer system.Encapsulation MIMU (Micro Inertial Measurement Unit) in the three-dimensional position calibration measurements head, MIMU (Micro Inertial Measurement Unit) is made up of six microsensors, comprises three little gyro A of single-degree-of-freedom ₁, A ₂, A ₃And three micro-acceleration gauge G ₁, G ₂, G ₃These six sensors are installed on cubical three normal surfaces, and their sensitive axes is vertical mutually, form the three-dimensional system of coordinate of measuring body, and as shown in Figure 5, Gx, Gy, Gz are respectively gyroscope G ₁, G ₂, G ₃Three sensitive axes, Ax, Ay, Az are micro-acceleration gauge A ₁, A ₂, A ₃Three sensitive axes, true origin O is positioned at the geometric center of measuring head, the lower end of measuring head is a measuring probe, end points is P, it is positioned on the reverse extending line of Gz axle.The final size of detecting head is 5 * 5 * 5cm ³, heavily about 480g.The movement rate of this measuring head be 5m/s to 10m/s, acceleration is less than 2g.It can accurately measure the three-dimensional coordinate of many each points on the arbitrary surface and the relative position between them.

During present embodiment work, as shown in Figure 6, measure basic point P0 with probe alignment earlier, then traverse measurement head measured some P1 of probe alignment.In this process, gyroscope is responsive and export the angle of rotation speed of three axles of measuring head, and accelerometer sensitive is also exported three axial acceleration of measuring head; Computer system solves the three-dimensional position of the relative basic point P0 of P1 point by the output of data line sampling sensor by computing.After measuring the P1 point, basic point P0 is retracted and aimed to measuring head, computer initialization, and the traverse measurement head is aimed at next measurement point P2 again, and computer solving goes out the position that P2 is ordered.Repeat said process, can finish the demarcation of the three-dimensional position of a plurality of measurement points on the arbitrary surface.

The function of computer system is the output signal of processes sensor and calculates measurement result.As shown in Figure 7, computing machine at first sample the angle rate signal of gyro output and accelerometer output acceleration signal and carry out error compensation; Calculate the attitude matrix of measuring head then, the calculating of this attitude matrix also is a most important part in the three-dimensional position calibrated and calculated method; Then the direction cosine matrix obtained by back of computing machine the acceleration signal along measuring head coordinate system direction that sampling is obtained decomposes, and obtains along the component of acceleration of geographic coordinate system direction; Speed and the position of measuring head in geographic coordinate system obtained in last machine integral operation as calculated respectively.Concrete steps are as follows:

1. extract with second order angular velocity and obtain angular velocity signal.Gyro is operated in the force feedback state, with the output of the form of digital quantity be angle increment, therefore, must obtain the relation between angle increment and the angular velocity.If gyro is from t _iTo t _iBe output as Δ θ during+T/2 _I1', from t _i+ T/2 is to t _iBe output as Δ θ during+T _T2', T is the sampling period.Extract with second order angular velocity, the angular velocity that gyro records is as follows: $\mathrm{\&omega;}\left(t_1\right)=\frac{1}{T}(3\mathrm{\&Delta;}{\mathrm{\&theta;}}_{\mathrm{<figure-callout\; id="1"\; label="i"\; filenames="C9811722600101.png"\; state="\{\{state\}\}">i</figure-callout>}1}^{\&prime;}-\mathrm{\&Delta;}{\mathrm{\&theta;}}_{i2}^{\&prime;})$ $\mathrm{\&omega;}(t_i+\frac{T}{2})=\frac{1}{T}({\mathrm{\&Delta;\&theta;}}_{\mathrm{<figure-callout\; id="1"\; label="i"\; filenames="C9811722600101.png"\; state="\{\{state\}\}">i</figure-callout>}1}^{\&prime;}+{\mathrm{\&Delta;\&theta;}}_{i2}^{\&prime;})----\left(7\right)$ $\mathrm{\&omega;}(t_i+T)=\frac{1}{T}(3{\mathrm{\&Delta;\&theta;}}_{i2}^{\&prime;}-{\mathrm{\&Delta;\&theta;}}_{i1}^{\&prime;})$

2. inertia components and parts error compensation.Error model according to shown in (1), (2) formula carries out closed loop compensation with Fig. 1, method shown in Figure 2.

3. the hypercomplex number differential equation and attitude angle finds the solution.The differential equation of substitution hypercomplex number as a result with step 2:

Find the solution (8) formula with fourth-order Runge-Kutta method and obtain rotating hypercomplex number q, again with q substitution following formula: α=-sin ^-1(T ₁₃) $\mathrm{\&beta;}={\mathrm{tg}}^{-1}\left(\frac{T_{23}}{T_{33}}\right)----\left(9\right)$ $\mathrm{\&gamma;}={\mathrm{tg}}^{-1}\left(\frac{T_{12}}{T_{11}}\right)$ Obtain the attitude angle of measuring head coordinate system.

4. decomposition acceleration.Computer sampling micro-acceleration gauge output signal, the q with step 3 solves, resolve into the acceleration signal along measuring head coordinate system direction along the component of acceleration of geographic coordinate system direction:

R _E=qR _bq ^-1(10) R in the formula _bBe the acceleration of accelerometer output, R _EBe the acceleration in the geographic coordinate system, expression formula is:

R _b＝A _xbi+A _ybj+A _zbk (11)

R _ε＝A _xEi+A _yEj+A _zEk (12)

5. output measurement result.To R _EThree components carry out numerical integration twice, obtain the movement velocity and the three-dimensional position of measuring head respectively.Its result is outputed on the display by computing machine, and the result also can comprise the attitude angle in the step 3.

Claims (2)

1, a kind of method of three dimension position measurement using miniature inertia measurement combination is characterized in that, comprises by three-dimensional position calibration measurements head and computer system composition measuring apparatus; Encapsulation MIMU (Micro Inertial Measurement Unit) in the said three-dimensional position calibration measurements head, MIMU (Micro Inertial Measurement Unit) is made up of six microsensors, these six microsensors adopt three single-degree-of-freedom gyroscopes and three micro-acceleration gauge aggregate erections on hexahedral three normal surfaces, its sensitive axes is vertical mutually, the three-dimensional system of coordinate of forming measuring body, the lower end of this measuring head is a measuring probe, the concrete measurement

Step is as follows:

1) earlier measure basic point P0 with probe alignment, the traverse measurement head is with measured some P1 of probe alignment then, and gyroscope is responsive and export the angle of rotation speed of three axles of measuring head, and accelerometer sensitive is also exported three axial acceleration of measuring head;

2) computer system obtains the three-dimensional position of the relative basic point P0 of P1 point by the output of data line sampling sensor by data processing;

3) measure the P1 point after, basic point P0 is retracted and aimed to measuring head, computer initialization, the traverse measurement head is aimed at next measurement point P2 again, the data processing of computer repeats processing obtains the position that P2 is ordered, can finish the demarcation of the three-dimensional position of a plurality of measurement points on the arbitrary surface by that analogy, its result is outputed on the display by computing machine.

Such as claim 1 the method for three-dimensional position measuring of art, it is characterized in that said computer data is handled and be may further comprise the steps:

1) extracts the angular velocity signal that little gyro is exported with second order angular velocity, the acceleration signal of the micro-acceleration gauge of sampling simultaneously output;

2) signal to little gyro and micro-acceleration gauge output carries out closed loop error compensation;

3) employing is obtained the attitude angle of measuring head coordinate system through the data of error compensation with fourth-order Runge-Kutta method by the hypercomplex number differential equation;

4) acceleration signal along measuring head coordinate system direction is resolved into along the component of acceleration of geographic coordinate system direction;

5) three components to the acceleration in the geographic coordinate system carry out numerical integration twice, obtain the movement velocity and the three-dimensional position of measuring head respectively.

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