CN1198526A - Method for measuring displacement and displacement sensor - Google Patents

Abstract

The present invention relates to a method for measuring displacement and its displacement sensor, belonging to the field of displacement precision measurement method and instrument. The method described by said invention includes creation of two sets of coordinate systems, and in one set of coordinate system a time checking point is set up, and a mathematical model between the time differences represented by displacement and uniform velocity and clock-pulse accumulation is established. The device described by said invention includes: the input end of space-time signal converter device is respectively connected with clock-pulse generator and displacement generator, and its output end is connected with the waveform shaping circuit. Said invention is easy to manufacture, simple in structure, anti-interference, can be made into intelligent instrument for precision measurement of displacement,

Description

The method of Displacement Measurement and displacement transducer

The invention belongs to the method and the device of displacement precision measurement

The precision measurement of displacement is often adopted the grid formula measuring method of increment type in order to satisfy range, precision and automatic electric Testing requirement, promptly total measurement length is divided into many little length according to pitch, accumulates summation with the mode of increment again.As the grating of a large amount of uses, magnetic grid, appearance grid, inductosyn (being electric grid), laser etc., pitch of every mistake (being the electric signal cycle) is sent a displacement pulse signals P _x, again with counter to P _xSummation gets final product.Its mathematical model is: $x=\∫\mathrm{vdt}=\∫\frac{\mathrm{dx}}{\mathrm{dt}}\mathrm{dt}=\∫\mathrm{dx}=\mathrm{\Σ\Δx}=\mathrm{\ΣW}=\mathrm{W\Σ}{P}_x---\left(1\right)$

In the formula: x-displacement, v-arbitrary motion speed, W-pitch, P _x-dfisplacement pulse

The characteristics of this method are as can be seen: measurement is irrelevant with movement velocity v, and the precision of measurement and resolution depend on pitch W.Therefore must groove more accurate, closeer (being that unit length groove number is more), cause production because of difficulty, cost height, and the close more easy more contaminated interference of groove.

The objective of the invention is at above-mentioned the deficiencies in the prior art, and proposed a kind of method and displacement transducer of Displacement Measurement, realize the displacement precision measurement, simplified structure is easy to processing, reduces cost, and is anti-interference and be easy to intellectuality.

For achieving the above object, technical scheme of the present invention is:

One,, adopt static relatively and with two cover coordinate systems of V motion at the uniform velocity, a wherein static cover has definite time examination point to the method for Displacement Measurement.When the displacement of particle P is represented with the coordinate figure of a cover coordinate system of motion, its size equals on P point and this coordinate system reference point (as true origin) and arrives static coordinate respectively and fasten the real time T that the time examination is put _iWith reference time T ₀Difference and the product of movement velocity V, i.e. x=V (T _i-T ₀).Wherein moving coordinate system can be by with T ₀For the time coordinate of fixed cycle is an equivalent substitute, the pass of two kinds of coordinate systems of space-time is V=W/T ₀It derives as follows in detail:

1, set up static relatively and with two cover coordinate system S and S ' of V motion at the uniform velocity.

According in the classical mechanics about the galilean transformation's formula in special relativity one joint, one-dimensional case only is discussed, the interconversion relation of displacement in two coordinate systems is as can be known:

x＝x′+Vt (2)

x′＝x-Vt (3)

Wherein: the displacement that x-characterizes with rest frame S,

The displacement that the coordinate system S ' of x '-usefulness uniform motion characterizes,

The movement velocity of V-S ', the t-time

2, set up 1 " time examination point " as Fig. 1 apart from reference point (as initial point o) W place among the rest frame S now, if during known t=0, two coordinate origins overlap, and particle P point is at the last non-displacement (being x '=0) of S ', and then P names a person for a particular job and o ' puts at t=T ₀Arrive the examination point constantly simultaneously, have according to (2) formula:

W=0+VT ₀Be W=VT ₀Or $V=\frac{W}{T_0}---\left(4\right)$

T ₀Be called the reference time, the reference point (herein being 0 ' point) at expression place, P point original position arrives the time of examination point.

As shown in Figure 2, no longer overlap with o ' point if the P point is subjected to displacement x ', the time that it arrives the examination point will become T _i, we are referred to as the real time, can release according to (2) formula and (4) formula

W＝x′+VT _ix′＝W-VT _i＝V(T ₀-T _i) (5)

Therefore, poor (displacement) of P point in the position on the s ' coordinate system become on the s coordinate system time poor at examination point place.Because two cover coordinate systems are notions of relative motion, can think that wherein any one is enclosed within moving and another set of motionlessly, and which the displacement of P point overlap coordinate representation by, and P point whichaway moves, may cause that all (5) formula has positive and negative number difference, therefore (5) formula more generally can be expressed as

x＝V(T _i-T ₀)＝VΔT＝V∑P _t (6)

Δ T is that a period of time is poor in the formula, and it can be obtained by some time clock summations, and constant V is equivalent to time clock P here _t" space equivalent ", promptly reach the purpose of " making time clock have spatial sense ".

As shown in Figure 3, if a plurality of examination points equally spaced are set on the S axle, just the displacement situation that can continuously order to P is sampled, and shows with (6) formula, this moment i=1,2,3 ..., reach the purpose of " using the time measurement space displacement ".

Because motion is relative, particle and examination point also are relative, are again identical by the time of at the uniform velocity advancing through a point of fixity again by the coordinate axis of space five equilibrium, and therefore upward example can have multiple equivalents, as Fig. 4-shown in Figure 7.

More than discussing is to be example with the rectilinear motion, suitable equally for gyration, and this moment, V represented uniform circular motion speed, and x represents angular displacement, uses symbol Δ θ instead, and all the other derivations are constant.

More than discussing is to be example with rectangular coordinate, to other can with any coordinate system of rectangular coordinate system equivalent transformation, as cylindrical-coordinate system, spherical coordinate system etc., same being suitable for.

Two, for displacement transducer, comprise the space-time chromacoder, clock and waveform finishing circuit, the input end of space-time chromacoder is connected with displacement generating device with clock respectively, and its output terminal is connected with the waveform finishing circuit.Wherein the space-time chromacoder comprises the relative motion bi-coordinate system of band time examination point, the signal amplification shaping circuit that is connected with this coordinate system output terminal, the timer counter chip that is connected with the output terminal of this circuit writes end and reads the end microprocessor linked with this chip.

Clock signal P _tImport a signal input part of this device timer counter chip, and the output terminal carry-out bit shifting signal pulse P of this chip _x, promptly finish from time signal P _tTo displacement signal P _xConversion.P _xSignal links with the waveform finishing circuit again, can export square wave and sine wave respectively.

Specifically described below in conjunction with accompanying drawing:

In Figure 13, the bi-coordinate system in the displacement transducer is made up of location survey head, motor, metal frame, rocking arm and moving gauge head; And signal and data processing partly are made up of signal amplification shaping circuit, timer counter chip and microprocessor, and this sensor also comprises clock and waveform finishing circuit.

Fig. 8, the machinery of gate sensor was partly installed and the formation of bi-coordinate system when Fig. 9 had reflected.At first, standard machinery index table [3], [4] are supported on the metal plate [1] by four pillars [2].Then, the time motor [9] in the gate sensor be installed in dull and stereotyped middle part, between pillar, motor shaft is concentric with the turntable armature spindle; One angled metal frame [6] is installed on the motor shaft, and is rotated with V at the uniform velocity with motor; One dihedral rocking arm [5] is installed in the lower end of turntable armature spindle, and this rocking arm lower end connects moving gauge head [7], and gauge head is rotated with arbitrary speed v and any direction synchronously with the turntable rotor.Also be equipped with on the plate identical with dihedral rocking arm radius, and the location survey head relative with moving probe location.

When output during rectangular wave, be connected with trigger at the output terminal of space-time chromacoder.

When sine wave output, connecting band bandpass filter behind trigger.

When the need video data, can on microprocessor, connect data display equipment.

During measurement, start motor, angled metal frame [6] is with at the uniform velocity V rotation, and moving gauge head rotates with arbitrary speed v and any direction with turntable, and purpose will be measured the angular displacement of turntable.When the dihedral frame skims over moving gauge head a and location survey head b, induce electric signal respectively and through being organized into pulse signal P _aAnd P _b, as shown in figure 10.Wherein keep static location survey head, its reference signal P with the earth _bTo keep phase place motionless, and with the synchronous moving survey signal P of rotation of turntable _aTo be reflected as with respect to P with respect to the locus difference Δ θ of b with a _bTime phase difference Δ T=T _i-T ₀, (under this simple situation, 360 ° of space angles are just in time numerically consistent with 360 ° of electrical angles (time angle)) is so can be by comparing the mistiming in two pulse signals forward position, promptly than the corner of trying to achieve turntable mutually $\mathrm{\Δ\θ}=\frac{W}{T_0}(T_i-T_0)=V{\mathrm{\ΔT}}_i=\mathrm{V\Σ}{P}_t$

At this moment Dui Ying bi-coordinate system as shown in figure 11, the earth (flat board) is S, moving gauge head a is the motion particle, location survey head b is S reference point (or initial point), at the uniform velocity the metal frame of rotation constitutes the S ' coordinate system of W=360 ° band time examination point, owing to rotating T time of arrival that uses phase property ground examination b point and a to order ₀And T _i

Cooperate the programmable timer counter chip as 8253 by computer processor, can realize the have living space dfisplacement pulse P of meaning of (7) formula computing and output device _xThereby, constitute by " space-time chromacoder ", be called for short the TST device, that promptly import TST is displacement Δ θ and clock signal P _t, and that output is displacement signal P _x

Adopt this TST device, cooperate the waveform finishing circuit again, displacement transducer when constituting at last, its block diagram as shown in figure 12, circuit diagram is as shown in figure 13.It can constantly export square wave or sine wave signal as displacement transducers such as gratings along with the increase of displacement, also can constantly show the angular displacement instantaneous value by digital display device.

Fig. 1: the relative motion bi-coordinate system of band time examination point; P point non-displacement among the figure, reference point is selected in initial point;

Fig. 2: the P point has displacement;

Fig. 3: examine or check a little examination to simple substance point more;

Fig. 4: the examination of the point-to-points particle of single examination;

Fig. 5: examine or check the examination of point-to-points particle more;

Fig. 6: the time coordinate by constant duration is the band time that constitutes to examine or check the examination of the moving coordinate system of point to simple substance point;

Fig. 7: time coordinate system is to the examination of many particles;

Fig. 8: the time displacement transducer in the bi-coordinate system front view;

The vertical view of Fig. 9: Fig. 8;

In Fig. 8, Fig. 9: 1. 4. turntable rotor 5. rocking arms of metal plate 2. pillars 3. turntable stators (shell)

6. metal frame 7. moves gauge head a 8. location survey head b 9. motor P _a-moving gauge head electric signal, P _b-location survey head

Electric signal, v-turntable arbitrary speed, V-motor constant speedpump, Δ θ-moving gauge head is with respect to the angle of location survey head

Displacement, promptly the turntable rotor is with respect to the angular displacement of shell reference point (b loca);

Figure 10: the induced signal time-domain diagram,

P _a-moving gauge head signal, P _b-location survey head signal, t-time, T ₀-the reference time, T _iI sampling of-Di

Real time, T _I+1I+1 sampling real time of-Di, Δ T _iI sampling time of-Di is poor, Δ T _I+1-

The i+1 time sampling time is poor;

Figure 11: " the relative motion bi-coordinate system of band time examination point " corresponding with the embodiment of Fig. 8 to Figure 10 reflection;

The S-rest frame, the turntable rotor angle location of the moving gauge head representative of a-, the turntable shell of b-location survey head representative

Reference point, S '-motor forms the W=360 ° of comprehensive shape in five equilibrium examination point back with the motion of V at the uniform velocity and with metal frame

The moving coordinate system that becomes;

Figure 12: the time displacement transducer theory diagram;

Figure 13: the time displacement transducer circuit diagram.

The present invention is with cheap, and the clock signal of being convenient to obtain is converted to the space displacement signal, carries out the precision measurement of displacement, is easy to process, reduces cost, simple in structure, anti-interference and be easy to intellectuality.

Claims (7)

1, a kind of method of Displacement Measurement is characterized in that:

(1) sets up static relatively and, obtain the interconversion relations of displacement in two cover coordinate systems with two cover coordinate system S and S ' of V motion at the uniform velocity;

(2) examine or check point at rest frame S apart from reference point W place establishing time, the mistiming that the particle P of examination moving coordinate system S ' and reference point arrive the examination point;

(3), change by P point and reference point arriving the time T that rest frame S goes up the examination point respectively with the particle P point among the moving coordinate system S ' and the alternate position spike x ' of reference point _iAnd T ₀Difference and the product representation of speed V, and with time T _iAnd T ₀Difference represent with time clock summation

x＝V∑P _t

X-displacement V-moving coordinate system movement velocity wherein

∑ P _t-accumulate the mistiming of expression by time clock.

2, a kind of displacement transducer is characterized in that this sensor comprises the space-time chromacoder, clock and waveform finishing circuit, and the input end of space-time chromacoder is connected with displacement generating device with clock respectively, and its output terminal is connected with the waveform finishing circuit.

3, displacement transducer according to claim 2, it is characterized in that the space-time chromacoder comprises the relative motion bi-coordinate system of band time examination point, the signal amplification shaping circuit that is connected with this coordinate system output terminal, the timer counter chip that is connected with the output terminal of this circuit writes end and reads the end microprocessor linked with this chip.

4, displacement transducer according to claim 3, the bi-coordinate system that it is characterized in that the relative motion of band time examination point comprises the dihedral rocking arm of the lower end that is contained in the turntable armature spindle, be contained in the moving gauge head of this rocking arm lower end, one angled metal frame is housed on the motor shaft, concentric and motor is contained in the plate middle part to the turntable armature spindle with motor shaft, be equipped with on the plate identical with dihedral rocking arm radius, and the location survey head relative with moving probe location.

5, displacement transducer according to claim 2 is characterized in that when output during rectangular wave, is connected with trigger at the output terminal of space-time chromacoder.

6, according to claim 2 or 5 described displacement transducers, it is characterized in that when sine wave output connecting band bandpass filter behind trigger.

7, displacement transducer according to claim 2 is characterized in that connecting data display equipment on microprocessor.

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