TWI414751B - Rotation angle measurement system - Google Patents

Abstract

For the precision measurement of rotary indexing angles, a measurement system has been proposed that consists of: a light source, a detector module and a signal processing module. A laser beam serves as the light source. The detector module which includes a beam splitter, a focus lens and a wedge mirror will detect the light beam. The beam is divided into two beams by the beam splitter. One of them propagates through the center of the focus lens. The wedge mirror is fixed on the rotary axis of the object. The laser beam travels through the focus lens and then is reflected by the wedge mirror. The reflected beam transmits through the focus lens again and also the beam splitter. The reflected laser beam is detected by the signal processing module. In the module there are a 2D position sensitive detector (PSD) and a signal processing circuit. And the circuit is connected with the 2D PSD. By this way, a rotary indexing angle measurement which has the advantages of being non-sensitive to eccentricity error and simple structure can be realized.

Description

Rotation angle measurement system

The invention relates to a measuring system, in particular to a rotating angle measuring system which is easy to set up and can avoid measurement errors caused by eccentricity.

According to the rapid development of science and technology, the precision of machining in the precision industry is getting higher and higher. Therefore, the development of high-precision testing equipment has become the focus of research and development. At present, when testing the rotating shaft of the object to be tested The main purpose is to detect the position and speed of the rotating shaft by a rotary encoder, and then to grasp the machining accuracy of the rotating shaft; although the rotary encoder can convert the mechanical displacement of the rotating shaft into an electrical signal, and the signal is After the processing, the position and speed of the rotating shaft are detected. When the rotary encoder is assembled, in addition to accurately mounting it on the rotating shaft and avoiding contact with water droplets or oil bodies, the object to be tested can be detected. The rotating shaft is detected. However, when the rotary encoder is mounted on the rotating shaft of the object to be tested, it is easy to cause measurement error due to eccentricity, which obviously affects the accuracy of the detection result, and has been improved.

Therefore, in view of the fact that when the rotary encoder is assembled on the rotating shaft of the object to be tested, it is easy to affect the lack of detection accuracy due to eccentricity, and after continuous experiment and research, a defect that can improve the existing defect is finally developed. this invention.

The invention mainly provides a rotation angle measuring system, which is capable of avoiding eccentricity during assembly by means of optical detection, thereby providing a rotation angle measurement which is convenient to erect and can avoid measurement error caused by eccentricity. The purpose of the system.

Based on the above objective, the main technical means of the present invention is to provide a rotation angle measuring system, which comprises a light source, a sensing group and a signal processing group, wherein: the light source is a laser; the sensing group is Receiving the laser and providing a beam splitter, a focusing lens and a wedge mirror, the beam splitter is configured to receive the laser and divide the laser into two beams, wherein a beam of light passes through the focusing lens vertically a center point, the wedge mirror is disposed on a rotation axis of the object to be tested, thereby receiving a laser focused by the focus lens and reflecting it back to the beam splitter; and the signal processing group is configured to receive the sensing a set of reflected lasers and a two-dimensional position sensitive detector and a signal processing circuit, the two-dimensional position sensitive detector is provided with a beam for receiving the laser through the wedge mirror and passing through the focusing lens and the beam splitter And entering the detection surface of the two-dimensional position sensitive detector, and the signal processing circuit is electrically connected to the two-dimensional position sensitive detector, and the signal processing circuit is applicable to the two-dimensional position sensitive detector Signal light output point should be processed can be accurately determined position of the rotary shaft analyte.

Further, the light source is a laser diode.

Still further, the wedge mirror is provided with a coupling that is coupled to the rotating shaft of the object to be tested.

Preferably, the detection surface of the two-dimensional position sensitive detector is a plane of 4 x 4 mm.

Preferably, the two-dimensional position sensitive detector has a resolution of up to 1 micrometer ( μm ) and is converted to an angle sensing resolution of about 0.03°.

According to the above technical means, the rotation angle measuring system of the present invention mainly utilizes a two-dimensional position sensitive detector to accurately determine the positional characteristics of the light spot on the detecting surface, and utilizes a two-dimensional position sensitive detector for two axes. The ratio of the direction is used as the parameter of the angle judgment, so that the angle can be detected at various rotation speeds, the stability of the rotation angle measurement system is relatively increased, and in addition, the rotation angle measurement system of the present invention can obtain the resolution. The high-precision detection of 0.03° or less can effectively avoid the angle measurement error caused by the eccentricity, thereby providing a rotation angle measuring system which is easy to set up and can avoid measurement errors due to eccentricity.

In order to understand the technical features and practical functions of the present invention in detail, and in accordance with the contents of the specification, the following is further illustrated in the preferred embodiment shown in the drawings, as shown in the first figure. The rotation angle measuring system of the present invention comprises a light source (10), a sensing group (20) and a signal processing group (30), wherein: the light source (10) is a laser, preferably The light source (10) is a laser diode; the sensing group (20) is configured to receive the laser and is provided with a beam splitter (21), a focusing lens (22) and a wedge mirror (23). Wherein the beam splitter (21) is adapted to receive the laser and divide it into two beams, wherein a beam of light passes vertically through a center point of the focusing lens (22), the wedge mirror (23) Provided on a rotating shaft (40) of the object to be tested, thereby receiving the laser focused by the focusing lens (22) and reflecting it back to the beam splitter (21), preferably, the wedge mirror (23) A coupling (231) coupled to the rotating shaft (40) of the object to be tested is provided; and the signal processing group (30) is configured to receive the reflected laser beam of the sensing group (20) and is provided with a Two-dimensional a position sensitive detector (31) (TWO-DIMENSION Position Sensitive Detector; 2D-PSD) and a signal processing circuit (32), wherein the two-dimensional position sensitive detector (31) is provided with a laser to receive the laser through the wedge shape The mirror (23) reflects and is incident on the detecting surface (311) of the two-dimensional position sensitive detector (31) via the focusing lens (22) and the beam splitter (21). Preferably, the two-dimensional position sensitive detecting The detection surface (311) of the device (31) is a 4x4 mm (mm) plane with a resolution of up to 1 micrometer ( μm ), which is converted to an angle sensing resolution of about 0.03° (360). °÷0.03°=12000 pulses), and the signal processing circuit (32) is electrically connected to the two-dimensional position sensitive detector (31), and the signal processing circuit (32) is applicable to the two-dimensional position sensitive detector (31) The signal output from the corresponding spot is processed to accurately determine the position of the rotating shaft (40) of the object to be tested.

The rotation angle measuring system of the present invention is used as shown in the first figure, wherein the laser beam is incident on the beam splitter (21), wherein a beam of light passes through the focusing lens (22) and is directed toward the wedge mirror. (23), and after passing through the focusing mirror (23) and passing through the focusing lens (22) and the beam splitter (21), the laser spot is caused to fall on the detecting surface of the two-dimensional position sensitive detector (31). (311), at this time, the two-dimensional position sensitive detector (31) senses the position of the center of gravity of the laser, and sets the center of the two-dimensional position sensitive detector (31) as the center position of the plane coordinate, and then The center of gravity of the spot will be at an initial angle as shown in the second figure, wherein when the axis of rotation (40) of the object to be tested is rotated, the spot of the laser will be as shown in the third figure, in the two-dimensional position. The center of the sensitive detector (31) is centered and rotated in a radius of R. The signal received by the two-dimensional position sensitive detector (31) can be used to know the change of the angle through the signal processing circuit (32). The amount, wherein the rotating shaft (40) of the object to be tested is a lead screw of a moving platform, the displacement of the platform can be derived from the pitch; As shown in principle be obtained by a collimator device of formula (1) in FIG.

Wherein, as shown in the fourth figure, the working radius relationship table of the light spot is different for each angle and focal length, and can be used with the two-dimensional position sensitive detector (31) detecting surface (311) of the same size; and by the two-dimensional position The principle of the sensitive detector (31) can obtain the equation (2), where I ₁ , I ₂ , I ₃ , I ₄ are the four output currents of the two-dimensional position sensitive detector (31), and D is a two-dimensional position sensitive The detector (31) detects the width of the face (311):

Wherein the current signal △ x and △ y amplifier circuit through a voltage signal and transmits the converted signal to the treated group (30), and then as shown in the FIG fifth of each quadrant representation:

The angle θ can be obtained by adding Δ x and Δ y obtained in equation (2) to equation (3) above. If the angle at the next moment is θ ', the amount of angular change during this time: △ θ (t)= θ '(t)- θ (t) (4)

Then, the Δ θ (t) of equation (4) is integrated with the time (t) from the measurement start t=0 to the measurement end t=n, and the total angular change during the measurement process can be obtained:

In addition, the signal processing flow of the signal processing circuit (32) is as shown in the sixth figure, and the rotation angle amount Δ θ can be conveniently obtained by means of signal processing.

According to the above technical means, the rotation angle measuring system of the present invention mainly utilizes a two-dimensional position sensitive detector (31) to accurately determine the positional characteristics of the light spot on the detecting surface (311), and utilizes two-dimensional Bit The ratio of the two axial directions of the sensitive detector (31) is used as the parameter of the angle judgment, so that the angle can be detected at various speeds, and the stability of the rotation angle measuring system is relatively increased, and further, the present invention The rotation angle measuring system can obtain high-precision detection with a resolution of 0.03° or less, so that the angle measurement error caused by the eccentricity can be effectively avoided, thereby providing an angle of rotation which is convenient to erect and can avoid measurement error caused by eccentricity. Test system.

The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any one of ordinary skill in the art can use the present invention without departing from the scope of the present invention. Equivalent embodiments of the invention may be made without departing from the technical scope of the present invention.

(10) ‧‧‧Light source

(20) ‧‧‧Sensing group

(21) ‧‧‧beam splitter

(22)‧‧‧focus lens

(23)‧‧‧Wedge mirror

(231)‧‧‧Couplings

(30) ‧‧‧Signal Processing Group

(31)‧‧‧Two-dimensional position sensitive detector

(311)‧‧‧Detection surface

(32) ‧‧‧Signal Processing Circuit

(40) ‧‧‧Rotary axis of the object to be tested

The first figure is a schematic diagram of the operation principle of the rotation angle measuring system of the present invention.

The second figure is a side view of a two-dimensional position sensitive detector of the present invention.

The third panel is a side view of the operation of the two-dimensional position sensitive detector of the present invention.

The fourth figure is a table showing the working radius of the light spot when the various angles and focal lengths of the present invention are different.

The fifth figure is the angle operation on the two-dimensional position sensitive detector of the present invention. Processing schematic.

Figure 6 is a block diagram showing the logical relationship of the signal processing circuit of the present invention.

(10). . . light source

(20). . . Sensing group

(twenty one). . . Beam splitter

(twenty two). . . Focusing lens

(twenty three). . . Wedge mirror

(231). . . Coupling

(30). . . Signal processing group

(31). . . Two-dimensional position sensitive detector

(32). . . Signal processing circuit

(40). . . Drill axis of the object to be tested

Claims (7)

A rotation angle measuring system includes a light source, a sensing group and a signal processing group, wherein: the light source is a laser; the sensing group is configured to receive the laser and is provided with a beam splitter, a focusing lens and a wedge mirror for receiving the laser and equally dividing the laser into two beams, wherein a beam of light passes vertically through a center point of the focusing lens, and the wedge mirror is set in a waiting a rotating shaft of the measuring object for receiving a laser focused by the focusing lens and reflecting it back to the beam splitter; and the signal processing group for receiving the reflected laser beam of the sensing group and providing one or two a dimensional position sensitive detector and a signal processing circuit, the two-dimensional position sensitive detector is configured to receive the laser reflected by the wedge mirror and enter the two-dimensional position sensitive detector via the focusing lens and the beam splitter On the detecting surface, the position of the spot on which the laser is incident on the detecting surface is set as the center of a plane coordinate, and when the wedge mirror rotates with the rotating axis of the object to be tested, the spot of the laser is centered on the detecting surface Rotate the center of the circle, and the news The processing circuit is electrically connected to the two-dimensional position sensitive detector, and the signal processing circuit can process the signal output by the corresponding spot on the two-dimensional position sensitive detector, so as to accurately obtain the object to be tested. The position of the rotary axis. The rotation angle measuring system of claim 1, wherein the light source is a laser diode. The rotation angle measuring system according to claim 1 or 2, wherein the wedge mirror is provided with a coupling combined with a rotating shaft of the object to be tested. The rotation angle measuring system of claim 3, wherein the detecting surface of the two-dimensional position sensitive detector is a plane of 4 x 4 mm. The rotation angle measuring system according to claim 4, wherein the two-dimensional position sensitive detector has a resolution of up to 1 micrometer ( μm ), and the resolution of the angle sensing is about 0.03°. . The rotation angle measuring system according to claim 1, wherein the detecting surface of the two-dimensional position sensitive detector is a plane of 4 × 4 mm. The rotation angle measuring system according to claim 1, wherein the two-dimensional position sensitive detector has a resolution of up to 1 micrometer ( μm ), and the resolution of the angle sensing is about 0.03°. .