CN111748770B

CN111748770B - Grating forming process of ultrasonic rotary encoder

Info

Publication number: CN111748770B
Application number: CN202010562064.6A
Authority: CN
Inventors: 韩志乐; 简小华
Original assignee: Suzhou Xisheng Technology Co ltd
Current assignee: Suzhou Institute of Biomedical Engineering and Technology of CAS
Priority date: 2020-06-18
Filing date: 2020-06-18
Publication date: 2022-04-05
Anticipated expiration: 2040-06-18
Also published as: CN114689098B; CN114689097A; CN111748770A; CN114689097B; CN114689098A

Abstract

The invention relates to a grating forming process of an ultrasonic rotary encoder, which comprises the following steps: 1) coating a material layer on the inner wall or the periphery of the stator; 2) the surface of the material layer is inwards processed in a sunken mode, and a plurality of long grooves are formed in the wall surface of the stator, wherein the cross section of each long groove is the same, and each long groove is an arc section which takes the center of the stator as the center of a circle; 3) forming a coating with consistent thickness on the surface of the long groove and the surface of the material layer which does not form the long groove, wherein the echo signals formed by the coating and the echo signals formed by the side wall of the stator have strength difference; 4) the coating material layer formed on the surface of the stator is peeled off from the surface of the stator, meanwhile, the coating formed in each long-shaped groove is a grating strip, a grating is formed between every two adjacent grating strips, and a plurality of gratings arranged in sequence form a grating. The invention has the advantages of simple operation and convenient implementation, and can greatly reduce the error of the grating on the ultrasonic echo detection.

Description

Grating forming process of ultrasonic rotary encoder

Technical Field

The invention belongs to the field of ultrasonic encoders, and particularly relates to a grating forming process of an ultrasonic rotary encoder.

Background

At present, a rotary encoder is also called a shaft encoder, and is a device that mainly converts a rotational position or a rotational amount into an electronic signal, and is applicable to industrial control, robotics, a dedicated lens, and the like.

The rotary encoder is mainly divided into an absolute encoder and an incremental encoder, wherein the incremental encoder calculates the rotating speed and the relative position by using a pulse detection mode and can output information related to rotary motion; an absolute type encoder will output the absolute position of the rotating shaft, which can be considered as an angle sensor.

Moreover, the operation modes of the encoder are generally classified into mechanical type, optical type, electromagnetic type, induction type, capacitance type and the like, the sensors combine the detection element and the processing circuit together, the structure is large, the diameter is generally more than 15mm, and the sensors cannot be well applied to the fields with narrow structures.

Meanwhile, in an ultrasonic encoder, motion information of a rotating shaft is mainly acquired through the intensity of an echo of ultrasonic waves, the intensity of the echo is mainly determined by a grating, and the current grating is generally composed of a large number of parallel slits with equal width and spacing, and is generally an optical device called as a grating, which is divided into a reflection grating, a transmission grating and the like. The grating is generally a planar structure, and is usually formed by photolithography, laser cutting, etching, and other techniques, in which a plurality of parallel notches are engraved on the surface of a specific material, such as glass or metal, to form a light-transmitting grating and an inverse grating in a staggered arrangement.

However, because the grating has high precision requirement and small size, the difficulty of manufacturing the grating on the surface of the cylinder is high, and the grating is usually manufactured by a planar grating curling method, which is easy to introduce errors at the curled joint.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a brand-new grating forming process of an ultrasonic rotary encoder.

In order to solve the technical problems, the invention adopts the following technical scheme:

the utility model provides an supersound rotary encoder's grid forming process, this supersound rotary encoder includes the sensor part, rotatory transmission part, the signal processing part, the sensor part includes that the cross-section is circular and is the stator of straight tube form, set up the rotor at the stator inside round the central line direction free rotation of stator, the fixed ultrasonic sensor who stretches into stator tip at the rotor that sets up, and round a plurality of grid strips of the circumference evenly distributed of stator, wherein there is strong and weak difference between the echo signal that grid strip formed and stator lateral wall formed, and form the grid between every two adjacent grid strips, the grid is constituteed to the grid that sets gradually, ultrasonic sensor is located the supersound echo detection zone that the grid formed, grid forming process is as follows:

1) uniformly coating a material layer which is easy to peel off from the surface of the stator on the inner wall or the periphery of the stator and the surface corresponding to the position of the ultrasonic sensor;

2) the surface of the material layer is inwards processed in a sunken mode, and a plurality of long grooves are formed in the wall surface of the stator, the sections of the long grooves are the same, the long grooves are arc sections with the center of the stator as the center of a circle, the long grooves are evenly distributed around the circumferential direction of the stator, and each long groove extends along the length direction of the stator;

3) forming a coating with consistent thickness on the surface of the long groove and the surface of the material layer which does not form the long groove, wherein the echo signals formed by the coating and the echo signals formed by the side wall of the stator have strength difference;

4) the coating material layer formed on the surface of the stator is peeled off from the surface of the stator, meanwhile, the coating formed in each long-shaped groove is a grating strip, a grating is formed between every two adjacent grating strips, and the gratings are formed by a plurality of gratings which are sequentially arranged.

Preferably, the grid is located at the periphery of the stator, the stator periphery being sheathed with a spacer sleeve, wherein the spacer sleeve divides the stator into a grid region, to which the layer of material is applied, and a non-grid region, before the layer of material is applied, and the spacer sleeve is removed from the stator periphery in step 4), before or after the layer of material is peeled off. The main purpose of the arrangement of the separating sleeve is as follows: 1. the separation of the grid areas is realized; 2. and the interference to the non-grid area is prevented during processing.

According to a specific implementation and preferred aspect of the invention, the material layer in step 1) is a water-soluble glue layer, a water-insoluble glue layer or a film layer.

Preferably, the stripping means is arranged in one-to-one correspondence with the material layer, and when the material layer is a glue layer capable of being dissolved in water, the stripping means is dissolution; when the material layer is a water-insoluble glue layer, the peeling means is heating or illumination; when the material layer is a film layer (e.g., parylene film), the peeling means is external force peeling.

According to a further embodiment and preferred aspect of the invention, the stator is made of plastic or rubber and the grating strips are metal coatings or metal parts, such that the echo signals formed by the grating strips are stronger than those formed by the side walls of the stator.

Preferably, the grid bars are arranged on the periphery of the stator, the grid bars are shaped and supported on the inner wall of the stator by using an inner supporting component before the step 2), the long grooves are formed by laser cutting or mechanical cutting, and the inner supporting component is drawn out from the interior of the stator after the step 4) is completed. The arrangement of the inner supporting part is simple, namely, the deformation of the stator is prevented.

Furthermore, the groove depth of each long-shaped groove is equal, and the distance between the bottom surface of each groove and the inner wall of the corresponding stator is 1/6-1/2 of the thickness of the stator wall.

Preferably, in step 3), the coating layer is formed on the outer circumference of the stator by spraying, evaporation, or sputtering. In this way, it is ensured that each grating strip is formed with equal thickness, and thus each grating strip provides equal echo intensity.

In addition, be formed with the mounting groove that extends along self length direction at the rotor tip, ultrasonic sensor has a plurality ofly and sets up side by side in the mounting groove, and the grid has the multiunit, and with ultrasonic sensor one-to-one, wherein every group grid distributes side by side along the length direction of stator, and is formed with 180 degrees/N's angular deviation between every two sets of adjacent grids in proper order, and N is the number of grid strip. Through the corresponding setting of a plurality of grids and ultrasonic sensor to can acquire more information, thereby make the turned angle and the slew velocity of the accurate calculation stator of supersound rotary encoder.

Preferably, each grating and one ultrasonic sensor constitute a set of information acquisition units, and the ultrasonic rotary encoder further includes an information acquisition unit having a single grating bar, wherein an angular deviation of 180 °/N is also formed between the single grating bar and the grating of the adjacent grating, N being the number of grating bars. Under the action of a single grid bar, each motion period can be easily seen, so that the ultrasonic rotary encoder can make accurate judgment conveniently.

Due to the implementation of the technical scheme, compared with the prior art, the invention has the following advantages:

the invention has the advantages of simple process of forming each grid strip, convenient implementation, accurate position of each grid strip and same formed circular arc section, thereby the distance of each finally formed grid is equal to greatly reduce the error of the grid on the ultrasonic echo detection.

Drawings

FIG. 1 is a schematic structural view (partially in section) of an ultrasonic rotary encoder of the present invention;

fig. 2a, 2b, 2c and 2d are corresponding schematic views of the state in step 1);

FIGS. 3a and 3b are schematic views of the corresponding states in step 2);

FIGS. 4a and 4b are schematic views of the corresponding states in step 3);

FIGS. 5a and 5b are schematic views of the corresponding states in step 4);

FIG. 6 is a schematic view of the structure of an ultrasonic rotary encoder of the present invention (absolute type encoder);

wherein: 1. a sensor portion; 10. a stator; 11. a rotor; 110. mounting grooves; 12. an ultrasonic sensor; 13. grid bars; 2. A rotation transmitting portion; 20. a rotating part; 21. an information transmission unit; 3. a signal processing section; 4. an inner support member; 5. a separation sleeve; 6. a layer of material; 7. coating; s, a grid area; f. a non-grid area; c. a long-shaped groove; q, an information acquisition unit.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise explicitly specified or limited, a first feature "on" or "under" a second feature may be directly contacted with the first and second features, or indirectly contacted with the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

As shown in fig. 1, the ultrasonic rotary encoder disclosed in the present embodiment includes a sensor portion 1, a rotation transmission portion 2 (which may be a slip ring, a rotary transformer, a rotary capacitor, a rotary fiber coupler, etc.), and a signal processing portion 3, wherein the rotation transmission portion 2 includes a rotation portion 20 for driving a detected shaft to rotate around its axis direction, and an information transmission portion 21 communicating with the sensor portion 1 and the signal processing portion 3, detection information obtained by the sensor portion 1 is transmitted to the signal processing portion 3 by the information transmission portion 21, and the signal processing portion 3 performs signal analysis to obtain measurement information.

The sensor part 1 comprises a stator 10 with a circular and straight-tube-shaped cross section, a rotor 11 arranged inside the stator 10 in a freely rotating manner around the center line direction of the stator 10, an ultrasonic sensor 12 fixedly arranged at the end part of the rotor 11 extending into the stator 10, and a plurality of grid strips 13 uniformly distributed around the circumference of the stator 10, wherein echo signals formed by the grid strips 13 are stronger than echo signals formed by the side wall of the stator, grids are formed between two adjacent grid strips 13, grids are formed by the grids arranged in sequence, and the ultrasonic sensor 13 is positioned in an ultrasonic echo detection area formed by the grids.

In this example, the stator 10 is a plastic part and the grid bars 13 are metal parts.

Specifically, the rotor is a detected shaft, and the diameter of the rotor is greater than or equal to 0.3 mm; the inner diameter of the stator is more than or equal to 0.4mm, and the outer diameter of the stator is more than or equal to 0.5 mm.

In this example, the outer diameter of the stator 10 is 1.0mm, the inner diameter of the stator is 0.8 to 0.9mm, and the outer diameter of the rotor 11 is 0.6 mm.

Specifically, the grid forming process comprises the following steps:

referring to fig. 2a to 2d (wherein fig. 2a is a front view, fig. 2b is a right view; fig. 2c is a front view, fig. 2d is a right view), 1), the stator 10 is supported on the inner wall by the inner supporting member 4 in a fixed shape, then the stator 10 is sleeved with the separating sleeve 5 which divides the stator 10 into the grid area s and the non-grid area f, and then the stator 10 in the grid area s is coated with the material layer 6 which is easy to be peeled off from the surface of the stator;

2) a plurality of elongated grooves c (shown in fig. 3a, which is a front view) are formed on the wall surface of the stator 10 and are recessed inward from the surface of the material layer 6, wherein the cross section of each elongated groove c is the same, each elongated groove c is an arc segment (shown in fig. 3b, which is a right view from the middle of the elongated groove) with the center of the stator as a center, the plurality of elongated grooves are uniformly distributed around the circumference of the stator, and each elongated groove extends along the length direction;

3) forming a coating 7 with a uniform thickness on the groove surface of the elongated groove c and the surface of the material layer 6 not forming the elongated groove (see fig. 4a and 4b, wherein fig. 4a is a front view, and fig. 4b is a right view from the middle of the elongated groove), wherein the echo signal formed by the coating 7 is stronger than the echo signal formed by the side wall of the stator 10;

4) and stripping off the material layer 6 (shown in a combined view of fig. 5a and 5b, wherein fig. 5a is a front view, and fig. 5b is a right view from the middle of the elongated slot) with the coating 7 formed on the surface from the surface of the stator 10, and drawing out the inner supporting member 4 from the inside of the stator 10, wherein the coating formed in each elongated slot c is a grid strip 13, a grid is formed between every two adjacent grid strips 13, and a plurality of grids arranged in sequence form the grid.

To further facilitate the above-described grid formation, the following measures are also adopted in this example.

In step 1), the material layer is a glue layer capable of dissolving in water, so that once the grid is formed, the whole stator is placed in water, and the material layer on the surface of the stator is quickly removed by the dissolution of the material layer.

Of course, the material layer can be peeled off conveniently by adopting a water-insoluble glue layer and a corresponding means of heating (or irradiating to degum the glue layer), parylene film layer and external force peeling.

In step 2), the machining is mechanical machining or laser machining, but it should be reminded that the groove depth of each long-shaped groove is equal, and the distance between the groove bottom and the corresponding inner wall of the stator is 3/5 of the stator wall thickness.

Preferably, in step 3), the stator is kept spinning down, and the coating layer is formed on the outer circumference of the stator by spraying, evaporation, or sputtering. In this way, it is ensured that each grating strip is formed with equal thickness, and thus each grating strip provides equal echo intensity.

In this example, the metal material is an acoustic reflective material, such as one of stainless steel, gold, aluminum, and the like, and is formed in the elongated groove on the outer periphery of the stator by vapor deposition.

As shown in fig. 6, a mounting groove 110 extending along the longitudinal direction of the rotor 11 is formed at the end of the rotor, a plurality of ultrasonic sensors 12 are arranged in the mounting groove 110 side by side, the grids correspond to the ultrasonic sensors 12 one by one, and the formed ultrasonic echo detection regions are distributed side by side along the longitudinal direction of the stator 10, an angular deviation of 180 °/N is formed between every two adjacent sets of grids, and N is the number of grid bars. Through the corresponding setting of a plurality of grids and ultrasonic sensor to can acquire more information, thereby make the turned angle and the slew velocity of the accurate calculation stator of supersound rotary encoder.

Each of the gratings and one ultrasonic sensor 13 constitute a group of information acquisition units q, and the ultrasonic rotary encoder further includes an information acquisition unit q having a single grating bar, wherein an angular deviation of 180 °/N is also formed between the single grating bar 13 and the grating of the adjacent grating, and N is the number of grating bars. Under the action of a single grid bar, each motion period can be easily seen, so that the ultrasonic rotary encoder can make accurate judgment conveniently.

Therefore, in this example, there are three groups of information obtaining units q, namely 3-bit gray code, i.e. absolute type encoder.

Also, the number of gray-coded bits can be increased by increasing the number of scale lines and the number of ultrasonic sensors, thereby increasing the resolution of the encoder.

In addition, taking an ultrasonic probe with a center frequency of 50MHz as an example, the transverse resolution of the ultrasonic probe is about 200um, and the size of the resolution determines that the minimum scale interval of the grating bars on the stator cannot be smaller than the transverse resolution of the ultrasonic probe, so that the required strong and weak signals can be acquired.

Assuming a lateral resolution of λ, the angular resolution of the encoder is up to 360 °/λ. We can improve the accuracy of the encoder by increasing the number of sensors.

In summary, in the embodiment, the sensor is designed by using the intensity of the reflected echoes of different reflectors when the ultrasonic waves encounter, and the rotation speed and the position of the rotating object are measured by using the principle of rotation coding.

Meanwhile, the ultrahigh frequency miniature ultrasonic sensor can be used for designing the structure of the encoder to be used for measuring the rotating speed and the position of a detected shaft with the diameter of more than 0.3mm, so that the ultrahigh frequency miniature ultrasonic sensor can be applied to the field of high-precision detection, such as in-vivo interventional medical imaging equipment, can effectively correct image distortion (NURD) and the like caused by rotational distortion, ensures the accuracy of images and has very good advantages.

The detection process of this embodiment is as follows:

(1) replacing the rotor with the detected shaft, forming a mounting groove at the end part of the rotor, and correspondingly distributing the ultrasonic sensors in the mounting groove and correspondingly positioning the ultrasonic sensors in an ultrasonic echo detection area formed by a plurality of grid bars;

(2) starting the rotary transmission part and the ultrasonic sensor, and acquiring signals of ultrasonic echoes under the synchronous rotation of a detected shaft and the ultrasonic sensor, wherein when the transmitting surface of the ultrasonic sensor is parallel to the tangent line of each grating strip, the reflected echo intensity is maximum Amax, when the transmitting surface of the ultrasonic sensor is over against the middle position of two adjacent grating strips, the reflected echo intensity is minimum Amin, and when the transmitting surface of the ultrasonic sensor is at other positions, the reflected echo intensity is between Amax and Amin;

(3) the ultrasonic sensor transmits the collected reflected echo intensity to the signal processing part, and the signal processing part performs data analysis and imaging, wherein the rotating speed and the rotating angle of the detected shaft can be calculated according to imaging information.

Meanwhile, in order to further improve the resolution of the encoder, in the step (1), three groups of information acquisition units can be arranged side by side to form a three-bit gray code, and of course, a plurality of groups of multi-bit gray codes arranged side by side can be used for detection, so that the motion data of the detected shaft can be more accurately obtained.

The present invention has been described in detail in order to enable those skilled in the art to understand the invention and to practice it, and it is not intended to limit the scope of the invention, and all equivalent changes and modifications made according to the spirit of the present invention should be covered by the present invention.

Claims

1. A grating forming process of an ultrasonic rotary encoder is characterized in that: supersound rotary encoder include sensor part, rotation transmission part, signal processing part, the sensor part includes that the cross-section is circular and is the stator of straight tube form, sets up at the inside rotor of stator, the fixed ultrasonic sensor who stretches into stator tip at the rotor and round a plurality of grid strips of the circumference evenly distributed of stator round the central line direction free rotation ground of stator, wherein the echo signal that the grid strip formed with there is strong and weak difference between the echo signal that the stator lateral wall formed, and forms the grid between every two adjacent grid strips, sets gradually the grid is constituteed to the grid, ultrasonic sensor is located in the supersound echo detection zone that the grid formed, grid forming process is as follows:

2) the surface of the material layer is inwards processed in a sunken mode, and a plurality of long grooves are formed in the wall surface of the stator, the sections of the long grooves are the same, the long grooves are arc sections with the center of the stator as the center of a circle, the long grooves are evenly distributed around the circumferential direction of the stator, and each long groove extends in the length direction of the stator;

4) and stripping off the surface from the surface of the stator to form a material layer with a coating, forming a grid strip on the coating in each long-shaped groove, forming a grid between every two adjacent grid strips, and forming the grids by a plurality of grids arranged in sequence.

2. The grating forming process of the ultrasonic rotary encoder according to claim 1, wherein: the grid is located the periphery of stator, before the coating forms the material layer, stator periphery cover is equipped with the spacer sleeve, wherein the spacer sleeve divides the stator into grid district and non-grid district, the material layer coating in the grid district, and in step 4), before peeling off the material layer or after, demolish the spacer sleeve from the stator periphery.

3. The grating forming process of the ultrasonic rotary encoder according to claim 1 or 2, wherein: the material layer in the step 1) is a glue layer capable of being dissolved in water, a glue layer insoluble in water or a film layer.

4. The process of claim 3, wherein: the stripping means and the material layer are arranged in one-to-one correspondence, and when the material layer is a glue layer capable of being dissolved in water, the stripping means is dissolution; when the material layer is a water-insoluble glue layer, the peeling means is heating or illumination; when the material layer is a film layer, the peeling means is external force peeling.

5. The grating forming process of the ultrasonic rotary encoder according to claim 1, wherein: the material of stator is plastics or rubber, the grid strip be metal coating or metalwork, the echo signal that grid strip formed is stronger than the echo signal that the stator lateral wall formed.

6. The process of forming a grating of an ultrasonic rotary encoder according to claim 5, wherein: the grid bars are arranged on the periphery of the stator, before the step 2) is carried out, an inner supporting component is adopted for shaping and supporting the inner wall of the stator, the long groove is formed by laser cutting or mechanical cutting, and after the step 4) is completed, the inner supporting component is taken out from the inside of the stator.

7. The process of claim 6, wherein: the groove depth of each long-shaped groove is equal, and the distance between the groove bottom and the corresponding stator inner wall is 1/6-1/2 of the stator wall thickness.

8. The grating forming process of the ultrasonic rotary encoder according to claim 6 or 7, wherein: in step 3), the coating layer is formed on the outer circumference of the stator by spraying, evaporation, or sputtering.

9. The grating forming process of the ultrasonic rotary encoder according to claim 1, wherein: rotor tip is formed with the mounting groove that extends along self length direction, ultrasonic sensor has a plurality ofly and sets up side by side in the mounting groove, the grid have the multiunit, and with the ultrasonic sensor one-to-one, wherein every group the grid is along the length direction of stator distributes side by side, and is formed with 180 degrees/N's angular deviation between every adjacent two sets of grids in proper order, and N is the number of grid strip.

10. The process of molding a grating of an ultrasonic rotary encoder according to claim 9, wherein: each of the gratings and one of the ultrasonic sensors constitute a group of information acquisition units, and the ultrasonic rotary encoder further includes an information acquisition unit having a single grating strip, wherein an angular deviation of 180 °/N is also formed between the single grating strip and the grating of the adjacent grating, and N is the number of grating strips.