CN100523723C - Angle displacement measurement method based on relevant algorithm - Google Patents

Abstract

An angular displacement measurement method based on the correlation algorithm adopts a rotating body which is provided with the whole circle of broad band or white noise random information data on the coaxial circular path in advance. In the course of uniform rotation of the rotating body, the continuous information data can be read by the reading head, which forms cyclical random signal. The output signal is transmitted from the reading head into the signal processing system, the signal and the sequences data stored in advance are operated, so as to obtain the instantaneous angular displacement of the current reading head related to the rotating body. The instantaneous angular displacements of different reading heads related to the rotating body in the same moment are subtracted, so as to obtain the angular displacement between the two reading heads. If the two reading heads read the information on the same track, the angular displacement can be carried out by operating the output signals which is output by the two reading heads. According to the conversion function between the angular displacement of the reading head obtained from the lined method and the measured angular displacement, the measured angular displacement can be obtained.

Description

A kind of angle displacement measurement method based on related algorithm

Technical field

The present invention relates to be applied to the angle displacement measurement technology of mechanical field, be specifically related to a kind of angle displacement measurement method based on related algorithm.

Background technology

Angle displacement measurement is that the gordian technique of mechanical field is again one of current techique simultaneously.Since mechanical industry is arranged, multiple measuring method and device have been invented.For example mechanical type index plate, circle grating, condenser type, magnetic inductive isogonism displacement measuring device.These method and apparatus have had a large amount of application in different occasions.

Existing various angle displacement measurement method invention is divided into two classes in essence.One class is static measuring method.For example, the mechanical type index plate is directly scribed the index line that indicates angle on index plate, and pointer is set on pedestal, thereby directly reads the angular displacement reading.And for example, capacitive angular sensor is converted into the variation of variable capacitance capacitor value with variation in angular displacement, thereby measures angular displacement by measuring capacitance value.Another kind of is method of counting, and this class measuring method is most typical to be the garden grating angular displacement sensor.The circle grating angular displacement sensor is converted to the angle that grating rotates with angular displacement, relatively rotates in the process at garden grating stator and moving plate, measures the count pulse number of grating output, thereby obtains value of angular displacement.Existing these methods all rely on high-precision stator and moving plate manufacturing accuracy very much, and manufacturing cost is than higher.For static measurement method, its static error and drift often are difficult for overcoming.

Summary of the invention

At the prior art above shortcomings, the objective of the invention is to propose a kind of low cost of manufacture, precision height, antinoise and the strong angle displacement measurement method of anti-part damage capability based on related algorithm.

The object of the present invention is achieved like this: a kind of angle displacement measurement method based on related algorithm is characterized in that:

With a disk body or a drum type body around its central shaft rotation, being on one or more circular traces of axle with its axis of rotation,, scribe or record whole ring signal in advance with methods such as light, electricity, magnetic or machineries, form the circular information track; Institute's recording signal is broadband or white noise random signal, perhaps also can be the pseudo random signal with abundant wideband random signal characteristic; Disk body or the drum body in the process that central shaft rotates, use the readhead alignment track, read the random signal of pre-recording on the track continuously; Along with advancing of track in the rotary course, the signal of read head output will be that the prerecording random signal is the random signal of going round and beginning again of the continuous circulation output of time cycle with the disc swing circle.

In the measurement, adopt any interlock method, make measured angle and two read heads with respect to the relation that keeps between the angle of turning axle determining.As long as promptly record the angle of two read heads, can calculate the measured angle displacement by the mathematical formulae of determining with respect to turning axle.

Measured angle:

ω＝f(θ)

Wherein: ω is a measured angle; θ is the angles of two read heads with respect to turning axle; The interlock method determined funtcional relationship of f (θ) for adopting.

This formula is determined by interlock method.By this formula, the measurement of measured angle displacement ω promptly is converted into the measurement of two read heads with respect to the turning axle angle theta.

The read head output signal is sent to signal processing apparatus and carries out signal Processing, and its Processing Algorithm is one of following:

A, in signal processing apparatus, stored identical random series in advance, on any one time point, data stream that reads and the data sequence of in advance depositing are carried out computing cross-correlation, obtain both related function value sequences, calculate the τ value of its first maximal value correspondence, i.e. time delay a between two signals, thus calculate the data reference position of data track on the current rotary body and the intermittent angle displacement between the read head:

Wherein, T ₀For rotary body rotates a circle the corresponding cycle;

The intermittent angle displacement of two read heads is subtracted each other, and eliminates, can calculate the measurement numerical value of two read head angles owing to the different homodynes of bringing in different pieces of information track initial position:

Wherein: α ₁, α ₂Be the momentary angular displacements separately of two read heads,

Homodyne for both data track reference positions;

Then, calculate the measured angle displacement by formula ω=f (θ).

If two read heads of B read identical information track, then both signals of output directly can be carried out related operation, try to achieve time delay value a, can calculate relative angular displacement between the two:

Wherein, T ₀For rotary body rotates a circle the corresponding cycle.

Then, calculate the measured angle displacement by formula ω=f (θ).

Further, what record in the different tracks can be identical random data sequence, also can be diverse random data sequence; Comprise clock information simultaneously.

Described read head can be provided with arbitrarily, optionally the angular displacement quantity of Ce Lianging and deciding; Read head can be set to read identical information track, also can be set to read different information tracks; Wherein the part read head can be set to be fixed on the pedestal, as the benchmark read head, so just can measure the absolute angle displacement of other read heads with respect to benchmark; Also the benchmark read head can be set, still can measure the relative angular displacement between any two read heads this moment.

The present invention adopts on circular trace coaxial on the rotary body broadband or the white noise random information data of the whole circle of preparation in advance, utilizes rotary body substantially at the uniform velocity in the rotary course, reads information data continuously with read head, forms periodic random signal.In this signal feed signals disposal system, carry out related operation with the data sequence of storing in advance and can obtain of the intermittent angle displacement of current this read head with respect to rotary body.Different reading is subtracted each other in same intermittent angle displacement in a flash with respect to rotary body, can obtain the momentary angular displacement between the read head.Can obtain the measured angle displacement according to the transfer function relation of determining by read head and measured angle displacement interlock method.

Compared to existing technology, the present invention has following advantage: at first, adopt the measuring technique of related algorithm can obtain extremely strong antinoise and partial data damage performance; Secondly, this measuring method can make full use of and have carving method and the parts that grown up in fields such as CD, disks now, has the measuring accuracy height, advantages such as low cost of manufacture.

Description of drawings

Fig. 1 is a measuring method schematic diagram of the present invention;

Fig. 2 is a universal signal disposal system schematic diagram of the present invention;

The another kind of disposal system schematic diagram that two read heads of Fig. 3 can adopt when reading same trajectories;

Fig. 4 is the autocorrelation function figure of wideband random signal;

The autocorrelation function figure of Fig. 5 white noise signal;

Fig. 6 is with T ₀Broadband or white noise random signal autocorrelation function figure for the cycle repetition;

Fig. 7 is as y (t)=x (t-a), and x (t) is the wideband random signal of T0 for the repetition period, the cross correlation function figure of y (t) and x (t).

Embodiment

Referring to Fig. 1, the present invention is based on the angle displacement measurement method of related algorithm, comprise the steps: it is with a disk body or a drum type body 1 (to call rotary body in the following text) around its central shaft 2 rotations, be on one or more circular traces of axle with its axis of rotation, with methods such as light, electricity, magnetic or machineries, scribe or record whole number of turns certificate in advance, form information track 3.The data of recording are one section broadband or white noise random data sequence, perhaps also can be the pseudo random signals with abundant wideband random signal characteristic.What record in the different tracks can be identical random data sequence, also can be diverse random data sequence.For the ease of the recovery of signal, the signal of recording can be through ovennodulation, and can comprise clock information simultaneously.

In the process of central shaft 2 rotation, aim at tracks at disk body or drum body 1, read the random data sequence of pre-recording on the track continuously with signal read head 4.Along with advancing of track in the rotary course, the signal of read head 4 outputs will be that the prerecording random data is the periodicity random data sequence of the continuous circulation output of time cycle with the disc swing circle.Its autocorrelation function satisfies characteristic shown in Figure 6.

In the measurement, adopt any interlock method, make measured angle and two read heads with respect to the relation that keeps between the angle of turning axle determining.As long as promptly record the angle 5 of two read heads, can calculate the measured angle displacement by the mathematical formulae of determining with respect to turning axle.

Measured angle:

ω＝f(θ)

Wherein: ω is a measured angle; θ is the angles of two read heads with respect to turning axle; The interlock method determined funtcional relationship of f (θ) for adopting.

This formula is determined by interlock method.By this formula, the measurement of measured angle displacement ω promptly is converted into the measurement of two read heads with respect to the turning axle angle theta.So only draw read head with respect to the turning axle angle theta among Fig. 1.

Read head 4 can be provided with arbitrarily, optionally the angular displacement quantity of Ce Lianging and deciding.Read head can be set to read identical information track, also can be set to read different information tracks.Wherein the part read head can be set to be fixed on the pedestal, as the benchmark read head, so just can measure the absolute angle displacement of other read heads with respect to benchmark.Also the benchmark read head can be set, still can measure the relative angular displacement between any two read heads this moment.

The data of read head output are sent to digital signal processing device and carry out computing, draw the angular displacement between any two read head positions.Then, calculate the measured angle displacement by formula ω=f (θ).

The signal processing system principle is as shown in Figure 2: read head read signal after pre-process, form data stream continuously.This data stream is that the random signal of prerecording is the continuous circulation repetition of large period with the disc swing circle.In signal processing apparatus, stored identical random series in advance.On any one time point, data stream that reads and the data sequence of in advance depositing are carried out computing cross-correlation, obtain both related function value sequences.Because the cycle repeatability of this related function, we only need calculate the τ value of first maximal value correspondence, i.e. time delay a between two signals.This value is corresponding to the data reference position of data track on the current rotary body and the intermittent angle displacement between the read head.Its pass is:

Wherein, T ₀For rotary body rotates a circle the corresponding cycle.

For any one moment of each read head, all can calculate of the intermittent angle displacement of data track reference position with respect to this read head.

Calculate two angular displacements between the read head, only need to calculate two read heads synchronization separately with respect to rotary body on the intermittent angle displacement of data reference position, subtract each other then and can obtain.If what two read heads read is different data track, and the reference position difference of these two data tracks, then also need to deduct a fixing homodyne (i.e. the angle of two data track initial positions).Thereby calculate the measurement numerical value of two read head angles:

Wherein: α ₁, α ₂Be the momentary angular displacements separately of two read heads,

Homodyne for both data track reference positions;

Then, can calculate the measured angle displacement according to formula ω=f (θ).

If two read heads read the data on the same track, then except that can adopting signal processing system shown in Figure 2, can also adopt signal processing system shown in Figure 3.The signal of two read head outputs is directly carried out related operation, tries to achieve time delay value a, can calculate relative angular displacement between the two:

Wherein, T ₀For rotary body rotates a circle the corresponding cycle.

Then, calculate the measured angle displacement by formula ω=f (θ).

According to the related function characteristic as can be known, the data that read head reads are if exist the part mistake, and are less to the measuring accuracy influence.

Conversion formula ω=f (θ) between read head relative angular displacement and the measured angle is only determined by interlock geometric relationship between the two.For example, directly be fixed on when read head on two limits of measured angle, turning axle is perpendicular to measured angle and when this angular vertex, and its pass is ω=θ.And for example, when measured angle linked by a gear reduction gear train and read head, its pass was ω=k θ.Wherein k is the ratio of gear of gear.

Embodiments of the present invention can have multiple.

Embodiment 1: rotary body adopts CD, and its information track is the circular trace on the CD, can adopt the method for suppressing behind the stamper of making earlier, also can adopt etch-recordable optical disk to carry out the laser imprinting and be made into.Read head adopts laser head to read.CD is driven by spindle motor and at the uniform velocity rotates, and spindle motor adopts servo-drive system control to guarantee stabilization of speed so that signal is reliably read.The existing parts that CD, CD manufacturing, CD burning, laser read head and various auxiliary servo-drive system can partly utilize related industries such as CD, DVD, blue-ray DVD to form are realized, thereby are realized low-cost.

Embodiment 2: rotary body adopts rigid disks, and its information track is the circular magnetic recording track on the disk, and read head adopts magnetic head.Associated components can partly utilize the existing parts of hard disk manufacturing to realize.

Embodiment 3: adopt mechanical mode portraying signal trajectory on the metal disc, as read head, come reading of data by the electric capacity between potential electrode and the disc with an approaching metal electrode.

In concrete enforcement, information track can adopt simulating signal also can adopt digital signal.

A kind of embodiment carries out record for adopting digital signal, and the digital signal after the recovery is delivered in the digital information processing system, carries out related operation at a high speed and angular displacement and calculates.

In the another kind of embodiment, adopt simulating signal to carry out record, the data that read head reads become digital signal after analog to digital conversion, send into and carry out high speed related operation and angular displacement calculating in the digital information processing system.

The present invention is based on the displacement of related algorithm measured angular, has quoted the notion of related function:

For x (t) is a sample function of ergodic stochastic process, and x (t+ τ) is the sample behind x (t) the time shift τ, if represent autocorrelation function with Rx (τ), it is defined as:

$R_x\left(\mathrm{\τ}\right)=\underset{T\→\∞}{\lim }\frac{1}{T}{\∫}_0^{T}x\left(t\right)x(t+\mathrm{\τ})\mathrm{dt}$

For x of different nature (t), autocorrelation function has following characteristic: as long as contain periodic component in the signal, its autocorrelation function is all unattenuated when τ is very big, and has obvious periodic.For the random signal that does not comprise periodic component,, τ goes to zero along with increasing the rapid decay of autocorrelation function.Wherein, the autocorrelation function of broadband random noise is a maximal value at τ=0 place, and decays to zero very soon, and the autocorrelation function of arrowband random noise then has slower attenuation characteristic.White noise (its signal band does not have limit for width) autocorrelation function is the δ function, is positioned at τ=0 place.Fig. 4 is the autocorrelation function shape of broadband random noise.Fig. 5 is the autocorrelation function of white noise, is an impulse function.

What adopt among the present invention is one section sufficiently long broadband random noise of intercepting or white noise signal sample signal, and with this section sample length (T ₀) for the cycle repeats to export the pseudo random signal of formation, the autocorrelation function shape of this type of signal is shown in Figure 6, is with sample length (T ₀) be the sharp-pointed characteristic in cycle.At τ=0, ± T ₀, ± 2T ₀± nT ₀Maximal value (sharp-pointed peak value) appears at the place.If signal is the discrete digital signal, τ=0, ± T will only appear in its maximal value ₀, ± 2T ₀± nT ₀At the place.

For ergodic stochastic process, the cross correlation function Rxy (τ) of two random signal x (t) and y (t) is defined as:

$R_{\mathrm{xy}}\left(\mathrm{\τ}\right)=\underset{T\→\∞}{\lim }\frac{1}{T}{\∫}_0^{T}x\left(t\right)y(t+\mathrm{\τ})\mathrm{dt}$

In particular cases, if y (t)=x (t-a), promptly y (t) only is the delay time signal of x (t), according to above-mentioned definition for autocorrelation function and cross correlation function, can be easy to derive:

R _xy(τ)＝R _x(τ-a)

Therefore, the cross correlation function of x (t) and y (t) and the autocorrelation function shape of x (t) are identical, just have a translation on the time shaft, and this translational movement equals the delay volume of y (t) with respect to x (t) signal.Thereby, if x (t) and y (t) are the above-mentioned T of thinking ₀Cycle wideband random signal or white noise signal, and y (t)=x (t-a), then its cross correlation function Rxy (τ) will be shape as shown in Figure 7, it is at τ=a, a ± T ₀, a ± 2T ₀... a ± nT ₀... sharp-pointed maximal value appears in the place of grade, and presents rapid attenuation characteristic in all the other positions.

If y (t) and x (t) are transmitting or are reading and introduced a spot of noise or fragmentary mistake in the process at signal, be y (t) and x (t) different on the life period not only, also there is certain different wave shape, can prove by simple derivation, as long as these noises and mistake are not especially severes, both related function waveforms are still similar with Fig. 7, and just peak value decreases.This has just guaranteed to adopt the measuring technique of related algorithm might obtain extremely strong antinoise and damage performance.

Claims (4)

1, a kind of angle displacement measurement method based on related algorithm, it is characterized in that: with a disk body or a drum type body around its central shaft rotation is rotary body, at the turning axle with rotary body is on one or more circular traces of axle, with light, electricity, magnetic or mechanical means, the whole number of turns certificate of preparation in advance forms information track; Prepared data are one section broadband or white noise random data sequence, or have the pseudo random signal of abundant wideband random signal characteristic;

In the process that central shaft rotates, use the readhead alignment track at disk body or drum type body, read the random data sequence of pre-recording on the track continuously; Along with advancing of track in the rotary course, the signal of read head output will be that the prerecording random data is the periodicity random data sequence of the continuous circulation output of time cycle with the rotary body swing circle;

The turning axle that read head is installed in rotary body is on the object of rotation axis, adopts any interlock method, makes measured angle displacement and two read heads with respect to keeping definite relation between the angle of turning axle:

ω＝f(θ)

Wherein: ω is the measured angle displacement; θ is the angles of two read heads with respect to turning axle; The interlock method determined funtcional relationship of f (θ) for adopting;

The data of read head output are sent to digital signal processing device and carry out computing, and Processing Algorithm is:

(1) when two read heads reads different information track, in digital signal processing device, stored identical random data sequence in advance, on any one time point, data stream that reads and the random data sequence of in advance depositing are carried out computing cross-correlation, obtain both related function value sequences, calculate the τ value of this first maximal value correspondence of related function value sequence, i.e. time delay a between two signals, thus calculate the data reference position of information track on the current rotary body and the intermittent angle displacement between the read head: $\mathrm{\α}=\frac{a}{T_0}\·360$ Degree

Wherein, T ₀For rotary body rotates a circle the corresponding cycle;

The intermittent angle displacement of two read heads is subtracted each other, and eliminates, thereby calculate the measurement numerical value of two read heads with respect to the angle of turning axle owing to the different homodynes of bringing of different information track reference positions:

Wherein: α ₁, α ₂Be the intermittent angle displacements separately of two read heads,

It is the homodyne of the information track reference position of two read head correspondences;

Then, calculate the measured angle displacement by formula ω=f (θ);

(2) when two read heads read same information track, the signal with two read head outputs in digital signal processing device directly carries out related operation, tries to achieve time delay value a, thereby calculates the angle of two read heads with respect to turning axle:

$\mathrm{\α}=\frac{a}{T_0}\·360$ Degree

Wherein, T ₀For rotary body rotates a circle the corresponding cycle;

Then, calculate the measured angle displacement by formula ω=f (θ).

2, the angle displacement measurement method based on related algorithm according to claim 1 is characterized in that: what record in the different tracks is identical random data sequence, or diverse random data sequence.

3, the angle displacement measurement method based on related algorithm according to claim 1 is characterized in that: comprise clock information in the data of prerecording.

4, the angle displacement measurement method based on related algorithm according to claim 1 is characterized in that: described read head is provided with individual arbitrarily; Read head is set to read identical information track, or is set to read different information track;

Part read head or be set to be fixed on the pedestal wherein as the benchmark read head, or the benchmark read head is not set.

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