Sensor of displacement, speed, position (below)

05mm or 0.

1mm wait) , and the reticle density of two grating is identical. If will indicate grating to turn inside the plane of its oneself,cross a very small angle, the reticle of two such grating intersects, when parallel light when grating of perpendicular illuminate staff guage, be in intersect the bulky stripe with area occurrence removed and alternant, equal light and shade, call Mo Er stripe. Because the reticle density of two grating is equal, namely bar is apart from ω equal, make the direction of the Mo Er stripe of generation and grating reticle direction roughly perpendicular. Its geometry relation sees graph 4-10(b) is become θ very hour, the pitch of Mo Er stripe is (this makes clear 4-16) the pitch of Mo Er stripe is the 1/ θ that bar is apart from times. When rear sight grating is mobile, mo Er stripe moves with respect to the direction with edge and grating shift perpendicular direction. When grating shift a bar is apart from ω when, mo Er stripe moves well and truly accordingly W of a pitch, that is to say both one to one correspondence. Should numerate only had moved the amount of Mo Er stripe, grating of knowable path had moved when making grating, how many bar is apart from and bar is apart from is foregone, the number of Mo Er stripe that so the mobile distance of grating can carry photoelectricity testing system to pass to moving undertakes computation, processing hind is measured automatically come out. The reticle of grating people is to cannot use naked eye to differentiate, but its Mo Er stripe is clear however and visible. Characteristic of this kind of enlarge is system of Mo Er stripe provide a characteristic alone. The another characteristic of Mo Er stripe, it is average effect. Because Mo Er stripe is by a certain number of grating reticle composition, if photoelectricity component accepts length to be 10mm, in ω = 0.

When 01mm, the signal that photoelectricity component accepts is by 1000 reticle is comprised, make the defect that go up so, for example discontinuous ground is little a few lines, can affect the photoelectricity result of thousand only. Accordingly, consumed bar measures length, the element that decides its precision is not a reticle, however the average precision of a group of lines. 2. The plant that grating surveys is being used actually in, most device is an illuminant, directive grating and photoelectricity component combination are together, those who say for reading head. The configuration of reading head is very much, but with respect to its smooth road is collected look can divide it is the following kinds. (Its principle graph sees head of 1) prismatic reading graph 4-11, the smooth classics lens that illuminant Q gives out becomes parallel light, illuminate mixes to grating Cl C: On, by lenticular second: the focusing of Mo Er stripe that forms on demonstrative grating C, find a place for on its scorched area photoelectricity component door in order to accept the signal of light and shade of Mo Er stripe. This kind of optical system is system of optics of Mo Er stripe is basic model. Head of this kind of prismatic reading, reticle is sectional for zigzag, bar is apart from for 0.

004illln, toothed dip angle determines according to the wavelengh of the refractive index of grating material and incident light. Nevertheless, span of this kind of grating is smaller, the space between two grating is little also. To protect grating face, often need to stick glass of a protection, and so little space is no good. Accordingly, umbriferous system is used in be used actually (graph 4-12) , it is in grating C1 and C: Between on the times umbriferous lens such as mount, , second: . Such, of C1 resemble with same size picture umbriferous in C, mo Er stripe is formed on. This kind of system substantially with in front identical, it is the distance between Cl and C2 spun only, satisfied real use requirement thereby. Head of this kind of reading basically is used in control of high accuracy coordinate and nicety to measure an instrument to go up. (2) is perpendicular and incident reading head head of this kind of reading basically is to be used at every millimeter 25, the system of vitreous transmission grating of 125 lines (graph 4-13) . From illuminant industry of 0 classics straight lens makes perpendicular illuminate reachs beam of light on G of rear sight grating, pass demonstrative grating C next: By photoelectricity component door is received. The distance between two grating ' it is the wavelengh according to effective light-wave is apart from O ／ to choose with grating bar again, namely ' : ～ ／ A. But this is theoretical value merely, even specific in be used actually choice. Graph 4, the 14 structural sketch map that are head of perpendicular and incident reading, illuminant 1 through lens 2 hind become parallel smooth illuminate to be in rear sight grating 3 with demonstrative grating 4 on, after forming Mo Er stripe by photocell 5 accept signal. In the graph 8 it is scroll bearing, it assured rear sight grating and demonstrative grating between constant clearance. Rear sight grating and reading head are installed respectively go up in fixed component and mobile component, rear sight grating uses pressing plate 7 clamp, reading head uses bolt 6 fixed, its precision is highest can amount to 0.

001/ 1000mm. Head of this kind of reading basically is used at the reflex bar system under line of every millimeter 25~50, if pursue,4-15 place is shown. Via straight lens, turn illuminant Q into parallel light, and an angle of incidence with be β to grating method extent (it is commonly) umbriferous go up to the reflection face of rear sight grating; Reflex the beam of light that come back to pass demonstrative grating first: Form Mo Er stripe, next classics lens: Receive signal by photoelectricity component P. Grating can be used at increment to measure way only, at present some grating reading heads set absolutely at 0 o'clock, when because power cut or other reason are caused,misremembering a number so, can be opposite afresh 0. It is there is a paragraph of small grating on rear sight grating, also have on demonstrative grating corresponding a paragraph of small grating, issue null signal when two paragraphs of small grating overlap, show in digital monitor come. 3. Linear grating detects the logistic block diagram that the line attempt 4-16 of device is grating measurement unit, to raise grating resolution precision, circuit adopted the plan of 4 times frequency. When grating reticle density is Mm of 50 lines ／ , use 4 photoelectricity component and 4 crack. Every other 4 grating pitch produces 1 ／ a pulse, resolution precision can raise 4 times. When demonstrative grating and rear sight grating move relatively, silicon photocell generates signal of sine wave electric current, these signal send to differential amplifier, repass plastics, those who make reach cosine square wave into two sine. Obtain pulse via differentiating circuit next, because pulse arises in the ascendant edge of square wave, if pursue,4-16 place is shown. Get pulse locally for what make reach, turn over sine and cosine square wave severally respectively so, next again differential, can get 4 pulse so. For differentiate to or retrorse motion, still use a few with doorknob Sin of 4 square wave, - Sin, Cos and - Cos(namely: A, C, B and D) and 4 pulse have logistic combination. When square to motion when, through with the door 1~4 is reached or the door gets 4 pulse are outputted; When turning over direction to move, through with the door 5~8 is reached or the door gets 4 pulse are outputted. Such, if the bar of grating is apart from,be 0.

02mm, every 1 pulse after 4 times frequency are equivalent to 0.

005mm, make resolution precision raises 4 times. Of course, times frequency still can increase 8 times frequency to wait, but compare difficulty to above of 20 times frequency commonly. 5, coder of pulse coder pulse is detecting element of position of a kind of optical type, code dish of direct outfit go up in runner shaft, spend the position and rate change in order to measure the corner coming back of an axis, its output signal to be electric pulse. This kind detects the characteristic of means is: Detect of means dispute contact, mix without attrition wear away, driving force is small, answer speed fast. Press the means of encode, can divide for increment type and absolute value type two kinds. 1. The working principle of coder of type of increment of increment type coder is shown like graph 4-17 place. In the graph (in A) , e is the radiation shape that waits for pitch pervious to light narrow seam a circle, for illuminant, , , it is photoelectricity component (photosensitive diode or photocell) , with installation of stagger phase angle. Rotate when disc when a pitch, below illuminant illuminate, be in photoelectricity component, go up so that pursue (the photoelectricity weaveform that B) place shows is outputted, signal of A, B is the sine wave that has phasic difference. After enlarge of amplifier of classics of this group of signal and plastics, must pursue (the output square wave that C) place shows, a photograph compares B photograph lead, its voltage amplitude is 5V. When setting posture of B of A photograph lead, for square Xiang Xuan turns, rotate to return way when photograph of A of B photograph lead, the whirl with differentiate coder square. The pulse that C photograph produces is fiducial pulse, say again at 0 o'clock pulse, it is the axis rotates a week is in fixed produce a pulse locally. If use whorl of cutting of numerical control lathe when, can regard this kind of pulse as dot of lathe tool feed and the signal that retreat a knife are used, won't buckle in order to assure cutting in disorder when whorl. The main shaft of the numerical control machine tool such as the revolution computation that this kind of pulse also can use at high speed to rotate or machining center stops signal definitely. Voltage of frequency of classics of signal of pulse of photograph of A, B alternates, get becoming the voltage signal of direct proportion with runner shaft rotate speed, it is signal of speed make a present of. 2. The defect of coder of type of increment of coder of absolute value type is, likely as a result of noise or other outside interference produces computation mistake, because of,be like power cut, cutting tool damaged and stop machine, preaccident cannot be found to carry out the proper place of the component again after the accident is divided. Very form coder uses the design on its disc to represent numerical value. Graph 4-18 place is shown code for the binary system dish, part of the blank in the graph is pervious to light, express " 0 " ; Increase a point (shadow) the part is not pervious to light, express " 1 " . Configure photoelectricity transformer according to the binary each link that forms on disc, in pursueing namely, with macula place shows the position, lying between disc from hind illuminate of side consumed source. This encode dish share 4 annulus, the photoelectricity transformer correspondence that each annulus configures is. In the graph, side is binary perch in, namely; Side is a binary system outside is low, be like " 1101 " , those who numerate is decimal " 13 " angle coordinate value. The main drawback of binary coder is law of design change random, in use changes many times at the same time, easy generation is more read by accident. The Ge Lai that shows like graph 4-19 place via improving the composition after codes dish, its characteristic is, every photograph adjacent between decimal numeral a binary code is different. Accordingly, the switch of design uses one digit only (of the binary system) undertake. So can read control to be in a several units by accident, raised dependability. Advantage: Coordinate is worth but from absolutely encode dish in numerate directly, won't have in accumulating a process by accident computation; Locomotive rate can rise, coder itself has mechanical memory function, even if causes coordinate value to keep clear of because of power cut or other reason, after electrify, still can find place of former absolutely coordinate. Its defect is, be more than when feed revolution when turning, need special processing, if use decelerate gear to join the coder of two above, compositive multistage detects device, but its structure complex, cost is high. 6, sensor of speed sensor speed assigns linear rate model with angular velocity model. The rate that speed sensor uses at unit of servo of numerical control system commonly detects in control, because sensor of this angular velocity is used morer. The photoelectricity coder that introduces in front, it besides use as outside angular displacement sensor, also be used as speed sensor at the same time. Additional, fast the dynamo also is a kind of commonly used speed sensor. 1. Measure fast dynamo it is can be change of mechanical rotate speed one kind the sensor of telegraphic date. It and general dynamo phase issue two characteristics than be like: (1) outputs voltage and rotate speed to become linear concern strictly; (The slope that 2) output electromotive force and rotate speed compare is big. Measure fast dynamo cent communicates and shed two kinds big continuously. Communication is measured fast the branch that the dynamo has synchronous, asynchronous again. The system is made in Electromechanical unifinication in, commonly used is communication different pacing fast dynamo and dc are measured fast dynamo, try to introduce respectively below. (1) communication is measured fast the dynamo is shown like graph 4-20 place, stator is two groups of winding that find a place for into horn each other in the space, rotor is structure of drag cup shape. Should bring to bear on on excitation winding when constant single-phase alternating voltage, dynamo job winding can output the alternating voltage signal that becomes direct ratio with size of rotate speed N: , its virtual value is an edge (in 4-17) type, -- the coil v/LIT all over the ground number that exports winding; -- the frequency of excitation voltage; K -- winding coefficient () ; -- the synthetic magnetic flux in electric machinery. (2) dc is measured fast dynamo it is general make it magneto, its job principle is shown like graph 4-21 place. Be in constant below magnetic field, when armature rotates with rotate speed N, the conductor cut lines of force on armature, in the instant generation carries inductive electromotive force for nothing, its value decides by next type: (In 4-18) type, -- electromotive force is invariable; -- magnetic flux. From on type can see, carry output voltage for nothing, it and rotate speed N become direct ratio. Should put in R of total resistor of laden resistor and armature loop. When, criterion (among 4-19) (4-20) good case changeless when, measure fast the output voltage V of the dynamo and rotate speed N become direct ratio. Return some elements to be able to be affected actually measure an outcome, for instance: (The change of 1) surroundings temperature makes winding resistor produces change, produce linear error thereby; (2) armature reacts, meeting influence measures the magnetic field that produces as a result of place of armature electric current namely fast the magnetic field of the dynamo, cause thereby measure an error; (The resistor of 3) armature loop changes along with the change of armature electric current, destroyed the line sexual relationship that outputs voltage and rotate speed. To reduce above effect, measure fast the magnetic circuit of the dynamo should be chosen enoughly saturated, still answer to be load current limitation inside lesser limits at the same time. 2. The use pulse coder of pulse coder is coder of a kind of circumgyrate, can use measure opposite displacement, the opposite angular displacement inside unit time is angular velocity. Accordingly, circumgyrate coder is detecting angular displacement while, deserve to be able to detect with timer an angular velocity. Pulse coder is in when passing an unit angular displacement, produce a pulse, graph 4-22 is the principle plan that makes speed detect with pulse coder. The PG(A) in the graph is the output pulse of pulse coder. Can see from inside the graph, the ascendant edge that outputs signal with pulse coder opens tally, have count to signal of high frequency clock; Drop with its the edge opens Suo Cunqi, to the computation inside tally the value undertakes locking up putting, such, suo Cunqi's content is the time that angular displacement place passes, beg its reciprocal, available rate. In this kind of usage, need is mixed according to the rotate speed limits of electric machinery detect the Zhong Pin when precision will decide is led and enumerated capacity. Exemple: If the rotate speed limits of electric machinery is Min of ／ of N=60 ～ 3000r, coder is R of 100 pulse ／ , it is when low speed, every second delivers 100 pulse, namely PG pulse cycle is 0.

01 seconds. If employ 8 tally, the condition that F of frequency of high frequency clock assures to tally does not spill over is 0.

≤ of 01f ／ ≤ of 256 F 25.

6kHz arrives to get taller detect precision, take F=25.

6kHz, it is when Min of ／ of 3000r of top rotate speed, the value of tally is (if 4-21) undertakes to pulse ascendant edge computation is 6; If drop to pulse,the edge undertakes computation is 5. See not hard, clock frequency is taller, measure fast error smaller. But clock frequency accepts tally capacity and restriction of frequency of working upper limit, cannot absoluteness ground is high, quantify an error to always exist so. 7, sensor of positional sensor position and displacement sensor are different, what what it measures is not the metabolic quantity of a paragraph of distance, pass however detect, whether to already reach some place certainly. Accordingly, it does not need to produce the imitate amount of successive change, the switch capacity that needs generation to be able to reflect some kind of condition only is OK. This kind of sensor is commonly used at numerical control the machine tool changes cutting tool, workpiece or workbench reachs the designated position or the auxiliary functionary signal such as journey limitation detects. Cent contact mixes positional sensor be close to type two kinds. Contact sensor is a kind of sensor of the information that can get two objects to whether be contacted; And be close to type sensor is a kind of sensor that uses differentiate to whether there is some object inside some limits. 1. This kind of contact parts of an apparatus that sensor uses micro-gap switch and so on can make contact position sensor. It has the following two kinds: (It uses sensor of 1) micro-gap switch position at detecting object position, a few kinds of construction that show like graph 4-23 place and shape of a distribution; (Sensor of position of type of 2 dimension matrix is like 2) graph 4-24 place is shown, it is used at manipulator palm inside commonly, in palmar inside constant installation has sensor of touch of many 2 values, in order to detects the osculatory position of oneself and some object. 2. Be close to type position sensor to be close to type position sensor to have a few kinds: ① electromagnetism type; ② photoelectricity type; Type of ③ static capacitance; ④ baric type; ⑤ ultrasonic type. The main job principle of these a few kinds of sensor can express with graph 4-25. (Sensor of 1) electromagnetism type is in these 5 kinds in the center, those who use at most is electromagnetism type sensor. Its working principle is as follows: When permanent magnet or one is connected when coil of high frequency electric current is close to a ferromagnetic, their lines of force distributings will produce change. Accordingly, can detect with another group of coil this kind of change. When ferromagnetic leans or be far from magnetic field, the flux change that it causes gives online circle response pulse of an electric current, the change of its amplitude direct ratio at magnetic flux. Graph 4-26 gave out the curve that the voltage of two end follows coil to ferromagnetic enters the speed of magnetic field and change, its voltage polarity depends on the object enters magnetic field or leave magnetic field. Accordingly, undertake to this voltage integral can reach signal of a 2 values, when integral value is less than fair threshold value, integrator outputs low n; Conversely, output tall n, state some content private savings is adjacent right now. Apparent, electromagnetism induction sensor can detect only electromagnetism material, helpless to material of other blame electromagnetism. To overcome this weakness, at present numerical control system uses photoelectricity detector increasingly to detect the position. (Sensor of 2) photoelectricity type and in front a few kinds of sensor photographs of the introduction are compared, this kind of sensor has volume small, reliability is high, detect positional precision is tall, answer speed to reach CMOS circuit quickly, easily to be allowed with TTL wait for an advantage. Its cent is pervious to light model with reflection model two kinds. Be in pervious to light model in photoelectricity sensor, glow parts of an apparatus is placed relatively with parts of an apparatus getting light, stay among have space, when the object that be measured reachs this one clearance, emissive light is obscured, receive parts of an apparatus thereby (photosensitive component) can detect give an object to had been achieved. Graph 4-27 is pervious to light model the interface circuit of sensor. In reflection photoelectricity sensor, after via be being measured the object is reflexed, the light that give out falls to detect again on parts of an apparatus. Its fundamental condition is sent with pervious to light model sensor is similar, but because be to detect reflex, the output electricity that gets so is lesser. Additional, to different object face, letter a confusion of voices is compared different also, accordingly, set is restricted a n appear very important. Graph 4-28 is the representative application of this kind of sensor, its circuit and pervious to light model sensor is roughly identical, be receiver only blast off extremely resistor is used more greatly, and for adjustable resistor. Because the photocurrent of reflection photoelectricity sensor is lesser,this basically is, and have very big dispersive sex. Sensor of position of contact of another kind of blame is suddenly Er component. Suddenly Er component is component of changeover of report of a kind of semiconductor magnetism (graph 4-29) , general by germanium (Ge) , antimony changes indium (InSb) , arsenic changes indium (the semiconductor material such as InAs) is made. Its job principle is component park magnetic field in, if end of A, B is connected with voltaic I, in C, D end can appear voltage, this kind of phenomenon calls suddenly Er effect. Will small magnet is fixed go up in athletic component, when the component stands by suddenly Er component, can produce suddenly Er effect, use circuit to detect a resistor voltage signal, can judge an object to whether reach the designated position. Suddenly Er component CNC Milling CNC Machining