CN202229739U - Absolute type angle measurement device - Google Patents

Abstract

The utility model discloses an absolute type angle measurement device, comprising a signal disk, a sensor and a processor; wherein a plurality of sensors are uniformly mounted on the positions near to the edge of the signal disk; the signal disk rotates by a cycle, the sensor scanning signal characteristic is in a complete periodic cosine; the processor is electrically connected with the sensor. The transmittance around a transparent disk changed according to a cosine function of one period and because the signal on the transparent disk is continuous, the precise angle value on any position is obtained and the sensor error is effectively eliminated.

Description

A kind of absolute type angle-measuring equipment

Technical field

The utility model relates to a kind of absolute type angle-measuring equipment.

Background technology

At present; The most frequently used method that takes measurement of an angle is to rely on the disc type optical encoder to measure; The disc type optical encoder belongs to the absolute value angular encoder, is to utilize digitally coded mode to represent the addendum modification of lighting from former, that is engraves the yardstick mark at rule; After secondary chi stops to move, survey the position of ordering scale with reading symbol.Traditional photoelectric encoder is to read coding at radial direction, but influenced by the code-disc radii size, and the closer to the center, scale is more little, all is affected with code length so sign indicating number is wide, and code bit number can not be done very high, and code bit number directly has influence on measuring accuracy.In addition, the conventional coding dish, measuring accuracy is limited by partition size, and the angle that within lattice, is obtained all is same value.

The utility model content

It is high that the utility model technical matters to be solved provides a kind of degree of accuracy, can both obtain the absolute type angle-measuring equipment of accurate angle value at an arbitrary position.

In order to solve the problems of the technologies described above, the technical scheme that the utility model provided is: a kind of absolute type angle-measuring equipment comprises signal panels, sensor and processor; Said sensor is provided with a plurality of, and evenly is installed in the position near the edge of signal panels; Said signal panels rotate a circle, and the signal characteristic of sensor scan is a complete cosine cycle; Said processor is connected with sensor electrical.

Said signal panels are toroidal.

Said signal panels are transparent plate, and sensor is an optical sensor; Transmittance around the said transparent plate becomes the cosine function of one-period to change.

The method that a kind of absolute type angle-measuring equipment takes measurement of an angle adopts aforementioned angle-measuring equipment, and concrete steps are:

1. throw light in a side of transparent plate;

2. optical sensor is gathered optical signal data at the opposite side of transparent plate, and the data that collect send to processor;

3. draw the anglec of rotation of transparent plate after processor is handled data.

The concrete grammar that the 3. middle processor of said step is handled data is: be installed in transparent plate n optical sensor on every side and collect a discrete cosine sequences x (0); X (1) ... X (n-1); Utilize Fourier transform to calculate then and try to achieve X (1), the arc tangent that calculates its imaginary part and real part ratio then just can obtain the phase place of this discrete series, and this phase value is exactly the accurate angle value at current disk place.

Saidly utilize Fourier transform to calculate to try to achieve the concrete formula of X (1) to be:

$X\left(1\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x\left(n\right)(\mathrm{COS}\frac{2\mathrm{\π}}{N}n-\mathrm{jSIN}\frac{2\mathrm{\π}}{N}n).$

After having adopted technique scheme; The utlity model has positive effect: the transmittance around the transparent plate of the utility model becomes the cosine function of one-period to change; Because the signal on the transparent plate is continuous; Therefore accurate angle value can both be obtained at an arbitrary position, and sensor error can be got rid of effectively.

Description of drawings

For the content that makes the utility model is expressly understood more easily,, the utility model is done further detailed explanation, wherein below according to specific embodiment and combine accompanying drawing

Fig. 1 is the structural representation of the embodiment 1 of the utility model.

Label in the accompanying drawing is:

Signal panels 1, sensor 2.

Embodiment

(embodiment 1)

Present embodiment comprises signal panels 1, sensor 2 and processor.

Signal panels 1 are toroidal.Sensor 2 is provided with a plurality of, and evenly is installed in the position near the edge of signal panels 1.Signal panels 1 rotate a circle, and the signal characteristic of sensor 2 scannings is a complete cosine cycle.Processor is electrically connected with sensor 2.

Certainly, signal panels 1 also can be other shapes.

Signal panels 1 can be transparent plate, and sensor 2 is the optical sensor that cooperates with it.Transmittance around the transparent plate becomes the cosine function of one-period to change.

The method that adopts aforementioned angle-measuring equipment to take measurement of an angle, concrete steps are:

1. throw light in a side of transparent plate;

2. optical sensor is gathered optical signal data at the opposite side of transparent plate, and the data that collect send to processor;

3. draw the anglec of rotation of transparent plate 1 after processor is handled data, concrete grammar is: be installed in transparent plate n optical sensor on every side and collect discrete cosine sequences a: x (0), x (1) ..., x (n-1); Utilize Fourier transform to calculate then and try to achieve X (1), formula is:

$X\left(1\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x\left(n\right)(\mathrm{COS}\frac{2\mathrm{\π}}{N}n-\mathrm{JSIN}\frac{2\mathrm{\π}}{N}n),$ The arc tangent that calculates its imaginary part and real part ratio then just can obtain the phase place of this discrete series, and this phase value is exactly the accurate angle value at current disk place.

Obtain the derivation of above-mentioned formula, and utilize Fourier transform to calculate that the principle of angle is:

To the spectrum analysis of discrete-time signal, can use the discrete time Fourier transform, i.e. DTFT.DTFT makes us can be in the frequency spectrum of numeric field frequency analysis signal and the frequency response characteristic of discrete system, but still has two practical problemss for DTFT: 1, numeric field frequencies omega=Ω T is a continuous variable, is unfavorable for calculating with computing machine.For the ease of carrying out the frequency-domain analysis and the processing of discrete-time signal and system with the method for numeral, only carry out discretize not enough in time domain, also must carry out discretize at frequency spectrum.2, the sequence handled of digitizing solution can only be for time-limited, so, the spectrum analysis problem of finite length sequence is discussed specially.

According to such requirement, drawn the notion of the discrete Fourier transformation of finite length sequence.The discrete Fourier transformation of finite length sequence abbreviates discrete Fourier transformation as, i.e. DFT (Discrete Fourier Transform).The definition of DFT is following.

Be provided with limit for length's sequence x (n), n=0,1,2, Λ, N-1, its discrete Fourier transformation DFT is defined as:

$X\left(k\right)=\mathrm{DFT}\left[x\left(n\right)\right]=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x\left(n\right)e^{-j\frac{2\mathrm{\π}}{N}\mathrm{kn}},$ 0≤k≤N-1

Can release according to above-mentioned formula:

$x\left(n\right)=\mathrm{IDFT}\left[X\left(k\right)\right]=\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}X\left(k\right)e^{j\frac{2\mathrm{\π}}{N}\mathrm{kn}},$ 0≤n≤N-1

Second formula is called discrete fourier inverse transformation (IDFT).First formula and second formula constitute a DFT transfer pair.DFT is the discrete Fourier transformation to finite length sequence, and the characteristics of DFT still are all to disperse at frequency spectrum in time domain, and all is time-limited.

DFT provides and has used a computer or dsp chip comes the fast algorithm FFT of a kind of method, the especially DFT of analytic signal and system, in many science and technology, has obtained using widely, and has promoted developing rapidly of Digital Signal Processing and related discipline.

X (k) is generally plural number, and the form that can be write as real part and imaginary part is:

X(k)＝X _R(k)+jX _I(k)

Or the form of amplitude and phase place:

Amplitude wherein | X (k) | be called the amplitude spectrum of sequence x (n); Phase place

is called the phase spectrum of sequence x (n), and they are respectively:

$\left|X\left(k\right)\right|=\sqrt{X_R^2\left(k\right)+X_I^2\left(k\right)}$

For the transparent plate 1 of present embodiment, at a time all periodic sampling N point then can be thought with N times of circular frequency sampling one-period cosine signal.According to nyquist sampling theorem, N＞=2.

After the sampling, we just obtain the finite length sequence x (n) in a certain moment like this, n=0, and 1,2, Λ, N-1, its discrete Fourier transformation is:

$X\left(k\right)=\mathrm{DFT}\left[x\left(n\right)\right]=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x\left(n\right)e^{-j\frac{2\mathrm{\π}}{N}\mathrm{kn}},$ 0≤k≤N-1

For the standard cosine signal of transparent plate 1, its frequency the point on the corresponding frequency domain be k=1.

$X\left(1\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x\left(n\right)e^{-j\frac{2\mathrm{\π}}{N}n}$

Then have

According to Euler's formula $\mathrm{Cos}{\mathrm{\ω}}_{0}t=\frac{e^{i{\mathrm{\ω}}_{0}t}+e^{-i{\mathrm{\ω}}_{0}t}}{2}$ Calculate:

$X\left(1\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x\left(n\right)(\mathrm{COS}\frac{2\mathrm{\π}}{N}n-\mathrm{jSIN}\frac{2\mathrm{\π}}{N}n)$

Be easy to try to achieve the absolute phase values of the cosine signal of discrete signal representative again according to the phase spectrum

of DFT; Suppose that our regulation discrete series phase place is 0 o'clock angle zero-bit for us, the phase place of then being tried to achieve is exactly the angle value that angle-measuring equipment squints.

Illustrate and be described below:

See Fig. 1, suppose to be provided with eight sensors 2, promptly N=8 supposes that disk has rotated 15 degree, and then first sampled point will drop on cos15 ° of position, each 2 π/8 phase place of cosine curve at interval of naming a person for a particular job of back.So disk rotates a circle, 8 sensors obtain corresponding data sequence x (0) with sampling, x (1), x (2), x (3), x (4), x (5), x (6), x (7); X (0)=cos15 °+a wherein, a is an arbitrary value.

The rest may be inferred, can obtain: x (0)=cos15 °+a, and x (1)=cos60 °+a, x (2)=cos105 °+a, x (3)=cos150 °+a, x (4)=cos195 °+a, x (5)=cos240 °+a, x (6)=cos285 °+a, x (7)=cos330 °+a.

The substitution formula gets:

X(1)＝(0.9659x1+0.5x0.707-0.2588x0+0.866x0.707+0.9659x1+0.5x0.707+0.2588x0+0.866x0.707)-j(0.9659x0+0.5x0.707-0.2588x1-0.866x0.707-0.9659x0+0.5x0.707-0.2588x1-0.866x0.707)＝3.863324+jx1.035124。

This moment, all a can be by cancellation, so a does not influence final result.

Calculate signal phase (1)=arctg (1.035124/3.863324)=arctg0.267936=14.9993 ° then, 0.0007 error only is to be caused by the mantissa that previous calculations is cast out.

Because the scope of arc tangent be-90 °～90 °, add that a simple quadrant judgement just can be with the phase projection to 0 that calculates °～360 °.

Above-described specific embodiment; Purpose, technical scheme and beneficial effect to the utility model have carried out further explain, it should be understood that the above is merely the specific embodiment of the utility model; Be not limited to the utility model; All within the spirit and principle of the utility model, any modification of being made, be equal to replacement, improvement etc., all should be included within the protection domain of the utility model.

Claims (3)

1. an absolute type angle-measuring equipment is characterized in that: comprise signal panels (1), sensor (2) and processor; Said sensor (2) is provided with a plurality of, and evenly is installed in the position near the edge of signal panels (1); Said signal panels (1) rotate a circle, and the signal characteristic of sensor (2) scanning is a complete cosine cycle; Said processor is electrically connected with sensor (2).

2. a kind of absolute type angle-measuring equipment according to claim 1 is characterized in that: said signal panels (1) are toroidal.

3. a kind of absolute type angle-measuring equipment according to claim 1 is characterized in that: said signal panels (1) are transparent plate, and sensor (2) is an optical sensor; Transmittance around the said transparent plate becomes the cosine function of one-period to change.

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