CN106979758A - A kind of three-dimensional measuring apparatus and method - Google Patents

Abstract

The embodiment of the present invention provides a three-dimensional measurement device and method. The three-dimensional measurement device includes: a projection unit, including an illuminator, a focusing lens group, a sinusoidal grating sheet, an imaging lens and a light screen arranged in sequence, and the focusing lens group and the imaging lens are both used The sinusoidal fringe image is clear and accurate; the light emitted by the illuminator sequentially passes through the focusing lens group, the sinusoidal grating sheet and the imaging lens to generate a sinusoidal fringe image; the sinusoidal fringe image is not modulated by the measurement object to generate an unmodulated grating fringe image, or the measurement object After modulation, a modulated grating fringe image is generated, and an unmodulated grating fringe image or a modulated grating fringe image is projected onto the light screen; an imaging unit collects an unmodulated grating fringe image or a modulated grating fringe image projected on the light screen; The unmodulated grating fringe image and the modulated grating fringe image collected by the unit are used to calculate the size of the measurement object. The application of the embodiments of the present invention can improve the accuracy of three-dimensional measurement.

Description

A three-dimensional measuring device and method

technical field

The invention relates to the technical field of optical measurement, in particular to a three-dimensional measurement device and method.

Background technique

With the increasing maturity of three-dimensional measurement technology, it has been gradually applied in many fields such as national defense, aerospace, machinery manufacturing, beauty, entertainment, etc., and is specifically used to obtain the three-dimensional size of the measurement object through three-dimensional image analysis.

At present, the three-dimensional measurement method based on the phase shift method has attracted widespread attention due to its characteristics of fast speed, simple operation and low cost. In the three-dimensional measurement method based on the phase shift method, the projection unit used is usually a projector. Since the image projected by the projector is a digital signal composed of pixels, the accuracy is low, and the brightness of the projector is limited. To a certain extent It affects the accuracy of 3D measurement.

Contents of the invention

The purpose of the embodiments of the present invention is to provide a three-dimensional measurement device and method to improve the accuracy of three-dimensional measurement. The specific technical scheme is as follows:

An embodiment of the present invention provides a three-dimensional measuring device, the device comprising:

The projection unit includes an illuminator, a focus lens group, a sinusoidal grating sheet, an imaging lens and a light screen arranged in sequence, and both the focus lens group and the imaging lens make the sinusoidal fringe image clear and accurate; the light emitted by the illuminator , sequentially passing through the focusing lens group, the sinusoidal grating sheet and the imaging lens to generate a sinusoidal fringe image; the sinusoidal fringe image is not modulated by the measurement object to generate an unmodulated grating fringe image, or is generated after being modulated by the measurement object A modulated grating fringe image, the unmodulated grating fringe image or the modulated grating fringe image is projected onto a light screen; an imaging unit collects the unmodulated grating fringe image or the modulated grating fringe image projected on the light screen An image; a processing unit that calculates the size of the measurement object according to the unmodulated grating fringe image and the modulated grating fringe image collected by the imaging unit.

Preferably, the focusing lens group includes plano-convex lenses, doublet lenses and plano-convex lenses arranged in sequence; the imaging lens includes plano-convex lenses.

Preferably, the projection unit further includes: a light homogenizer, a light splitter and a collimator lens; the light homogenizer, the light splitter and the collimator lens are sequentially arranged between the illuminator and the focusing lens Between groups, the light homogenizer is close to the illuminator; the light homogenizer makes the light intensity of the light emitted by the illuminator uniform, and narrows the divergence angle of the light emitted by the illuminator; the light splitter The stray light contained in the light passing through the homogenizer is filtered; the collimating lens adjusts the light passing through the light splitter into a parallel beam.

Preferably, the illuminator includes an LED array; the aperture of the homogenizer is larger than the section of the LED array.

Preferably, the device further includes: a position adjuster; the position adjuster moves the position of the sinusoidal grating sheet in a direction perpendicular to the optical path generated by the projection unit, so as to modulate the grating collected by the imaging unit The phase of the fringe image.

Preferably, the device further includes: a control unit; when the measurement object is not placed in front of the light screen, the control unit uses the position regulator to adjust the The sinusoidal grating sheet in the projection unit is phase-shifted, so that the imaging unit collects the unmodulated grating fringe image in which the sinusoidal fringe image has not been modulated by the measurement object; when the measurement object is placed in front of the light screen , using the position regulator to shift the phase of the sinusoidal grating in the projection unit according to a preset phase shift value, so that the imaging unit can collect the sinusoidal fringe image modulated by the measurement object Modulates the raster fringe image.

Preferably, the imaging unit collects an unmodulated grating fringe image of the sinusoidal fringe image that has not been modulated by the measurement object; collects a modulated grating fringe image of the sinusoidal fringe image modulated by the measurement object; the processing The unit uses a dual-frequency heterodyne method to obtain the size of the measurement object by analyzing the modulated grating fringe image and the unmodulated grating fringe image collected by the imaging unit.

The embodiment of the present invention also provides a three-dimensional measurement method, which is applied to a three-dimensional measurement device. The three-dimensional measurement device includes: a projection unit, an imaging unit, and a processing unit; the method includes: using the projection unit to generate a sinusoidal fringe image ; using the imaging unit to collect the modulated grating fringe image of the sinusoidal fringe image modulated by the measurement object, and the unmodulated grating fringe image not modulated by the measurement object; using the processing unit, according to the The modulated grating fringe image and the unmodulated grating fringe image collected by the imaging unit are used to calculate the size of the measurement object.

Preferably, the method further includes: using a position adjuster to move the position of the sinusoidal grating sheet in the projection unit, so as to change the phase of the grating fringe image collected by the imaging unit.

Preferably, before the step of using the imaging unit to acquire a modulated grating fringe image of the sinusoidal fringe image modulated by the measurement object, and an unmodulated grating fringe image not modulated by the measurement object, the The method further includes: when the measurement object is not placed in front of the light screen, using the position adjuster to shift the phase of the sinusoidal grating in the projection unit according to a preset phase shift value; When the measurement object is placed in front of the light screen, use the position regulator to shift the phase of the sinusoidal grating in the projection unit according to the preset phase shift value; using the imaging unit, The step of acquiring a modulated grating fringe image of the sinusoidal fringe image modulated by the measurement object, and an unmodulated grating fringe image not modulated by the measurement object includes: using the imaging unit to collect the sinusoidal fringe image An unmodulated grating fringe image that has not been modulated by the measurement object; using the imaging unit, collecting a modulated grating fringe image of the sinusoidal fringe image modulated by the measurement object; using the processing unit according to the imaging The step of calculating the size of the measurement object from the modulated grating fringe image and the unmodulated grating fringe image collected by the unit includes: using a dual-frequency heterodyne method to analyze the four images collected by the imaging unit The modulated grating fringe image and four unmodulated grating fringe images are used to obtain the size of the measurement object.

The embodiment of the present invention provides a three-dimensional measurement device and method. The three-dimensional measurement device includes a projection unit, an imaging unit, and a processing unit. The projection unit includes an illuminator, a focusing lens group, a sinusoidal grating, an imaging lens, and a light screen arranged in sequence; The light emitted by the illuminator sequentially passes through the focusing lens group, the sinusoidal grating sheet and the imaging lens to generate a sinusoidal fringe image. The sinusoidal fringe image is not modulated by the measurement object to generate an unmodulated grating fringe image, or modulated by the measurement object to generate a modulated grating fringe image The image, the unmodulated grating fringe image or the modulated grating fringe image is projected onto the light screen, wherein both the focusing lens group and the imaging lens make the sinusoidal fringe image clear and accurate; the imaging unit can collect the unmodulated grating fringe image projected on the light screen Or modulate the grating fringe image; the processing unit calculates the size of the measurement object according to the unmodulated grating fringe image and the modulated grating fringe image collected by the imaging unit.

In this way, the sinusoidal fringe image generated by the projection unit uses the simulated light generated by the sinusoidal grating sheet. Therefore, the grating fringe image generated by the sinusoidal fringe image collected by the imaging unit can carry more abundant and accurate size information of the measured object, making the processing The dimensions of the measured object calculated by the unit are more accurate. Of course, implementing any product or method of the present invention does not necessarily need to achieve all the above-mentioned advantages at the same time.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

FIG. 1 is a schematic structural view of a three-dimensional measuring device according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a projection unit in an embodiment of the present invention;

Fig. 3 is a kind of flowchart of the three-dimensional measurement method of the embodiment of the present invention;

Fig. 4 is a schematic diagram of an application of the three-dimensional measurement method of the embodiment of the present invention.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The embodiment of the present invention discloses a three-dimensional measuring device, see FIG. 1, which is a schematic structural diagram of the three-dimensional measuring device according to the embodiment of the present invention; as shown in FIG. 1, the device includes: a projection unit 101, an imaging unit 102 and processing unit 103.

The projection unit 101 includes an illuminator 1011, a focusing lens group 1012, a sinusoidal grating sheet 1013, an imaging lens 1014 and a light screen 1015 arranged in sequence; both the focusing lens group 1012 and the imaging lens 1014 make the sinusoidal fringe image clear and accurate.

Wherein, illuminator 1011 , focusing lens group 1012 , sinusoidal grating sheet 1013 , imaging lens 1014 and light screen 1015 are arranged sequentially on the horizontal plane to form projection unit 101 . Specifically, the illuminator 1011 is used to generate a light source; the string grating sheet 1013 is used to modulate the light generated by the illuminator into a sinusoidal fringe image; the focusing lens group 1012 and the imaging lens 1014 are used to make the generated sinusoidal fringe image clearer and more accurate; The object is placed at a position where a clear sinusoidal fringe image can be observed, and the light screen 1015 is placed behind the measurement object. The light screen 1015 is used to receive the sinusoidal fringe image without being modulated by the measurement object to generate an unmodulated grating fringe image, or after being modulated by the measurement object Generates a modulated raster fringe image.

In the first step, the light emitted by the illuminator 1011 passes through the focusing lens group 1012 , the sinusoidal grating sheet 1013 and the imaging lens 1014 in sequence to generate a sinusoidal fringe image.

In practical applications, the light emitted by the illuminator 1011 passes through the optical path composed of the focusing lens group 1012, the sinusoidal grating sheet 1013 and the imaging lens 1014 to generate a sinusoidal fringe image of analog light; compared with the digital signal generated by the projector The sinusoidal fringe image is a modulated grating fringe image generated after the sinusoidal fringe image of simulated light is modulated by the measurement object, which can carry richer and more accurate size information of the measurement object, thus making the final calculated size of the measurement object more accurate.

In addition, both the focusing lens group 1012 and the imaging lens 1014 can make the generated sinusoidal fringe image clearer, so as to ensure the accuracy of the calculated measurement object size.

In the second step, the sinusoidal fringe image is not modulated by the measurement object to generate an unmodulated grating fringe image, or modulated by the measurement object to generate a modulated grating fringe image, and the unmodulated grating fringe image or the modulated grating fringe image is projected to the light screen 1015 .

In practical applications, it is necessary to generate grating fringe images in two cases: one is the situation where no measurement object is placed before the light screen 1015, the sinusoidal fringe image is directly projected on the light screen 1015, and at this time, it is displayed on the light screen 1015 One is that the unmodulated grating fringe image is generated without being modulated by the measurement object; the other is the situation where the measurement object is placed before the light screen 1015, and the sinusoidal fringe image is projected on the light screen 1015 after being reflected by the measurement object. On the screen 1015 is a modulated grating fringe image generated after being modulated by the measurement object.

In this way, the processing unit 103 can calculate the size of the measurement object according to the unmodulated grating fringe image and the modulated grating fringe image collected by the imaging unit 102 from the light screen 1015 .

The imaging unit 102 collects the unmodulated grating fringe image or the modulated grating fringe image projected on the light screen 1015 .

In practical applications, the imaging unit 102 can be a charge-coupled device (Charge-Coupled Device, CCD) camera, and the unmodulated grating fringe image or the modulated grating fringe image projected on the light screen 1015 by the projection unit 101 is collected by taking pictures, so as to provide The processing unit 103 is used for calculating the size of the measurement object.

The processing unit 103 calculates the size of the measurement object according to the unmodulated grating fringe image and the modulated grating fringe image collected by the imaging unit 102 .

In practical applications, the processing unit 103 may be a computer, which can collect the unmodulated grating fringe image and the modulated grating fringe image according to the imaging unit 102. Specifically, the phase between the unmodulated grating fringe image and the modulated grating fringe image can be compared Difference information to calculate the size of the measured object.

It can be seen that in the three-dimensional measuring device proposed by the embodiment of the present invention, the sinusoidal fringe image projected by the projection unit on the light screen is the simulated light generated by the sinusoidal grating sheet, therefore, the grating generated by the sinusoidal fringe image collected by the imaging unit The fringe image can carry richer and more accurate size information of the measurement object, making the size of the measurement object calculated by the processing unit more accurate.

In a preferred embodiment of the present invention, the focusing lens group 1012 includes plano-convex lenses, doublet lenses and plano-convex lenses arranged in sequence; the imaging lens 1014 includes plano-convex lenses.

In practical application, the focusing lens group 1012 is composed of three lenses, which are lens 1, lens 2 and lens 3 from left to right; wherein, lens 1 is a plano-convex lens with a focal length of 300 mm, and lens 2 is a double lens with a focal length of 75 mm. Cemented lens, lens 3 is a plano-convex lens with a focal length of 100 mm. In the projection unit, the lens 1 in the focusing lens group 1012 is close to the illuminator 1011, the distance between the lens 2 and the lens 1 is 60±5 mm, and the lens 3 and the lens 2 are close together. By encapsulating the three lenses in the metal lens barrel, the optical axes of the three lenses in the focusing lens group 1012 are strictly coincident.

The imaging lens 1014 may be a plano-convex K9 lens with a focal length of 200 mm and a diameter of 80 mm.

It can be seen that the focusing lens group 1012 and the imaging lens 1014 shorten the length of the optical path, so that the sinusoidal fringe image generated by the light emitted by the illuminator passing through the sinusoidal grating sheet 1013 is clearer and more accurate.

In addition, the distance between the focusing lens group 1012 and the imaging lens 1014 can also be adjusted to match the size of the measurement object; specifically, when the size of the measurement object is large, the distance between the focusing lens group 1012 and the imaging lens 1014 can be increased. When the size of the measurement object is small, the distance between the focusing lens group 1012 and the imaging lens 1014 can be reduced; and, for a measurement object with a small size, a sinusoidal grating sheet 1013 with a smaller fringe density can be selected.

In yet another preferred embodiment of the present invention, the illuminator 1011 includes an LED array.

In practical applications, the maximum power of a single LED lamp bead in the LED array can be 18W, and the maximum light intensity can be 2500LM. The LED lamp beads are combined into a 3×3 LED array through a light source driver.

It should be noted that the most widely used projection unit is the projector. Since the image projected by the projector is a digital signal composed of pixels, the precision is low, and the brightness of the projector is limited, which affects the three-dimensional image to a certain extent. The accuracy of the measurement. Compared with the sinusoidal fringe image generated by the projector, in the embodiment of the present invention, the sinusoidal fringe image generated by the LED array through the sinusoidal grating sheet 1013 can carry a richer and richer image in the grating fringe image generated after being reflected by the measurement object. Accurately measure the size information of the object, and then make the final calculated size of the measured object more accurate.

In addition, the LED array can also adjust the cross-sectional size of the LED array and the light intensity of the LED lamp beads according to the light reflectance and shape of the measurement object, so as to realize the adjustable brightness of the illuminator, so that the three-dimensional measuring device provided by the embodiment of the present invention can be applied to It is more flexible to measure the size of objects with different colors, different roughness and different shapes. At the same time, for the sinusoidal grating sheet 1013 with different contrasts, the LED array can cooperate with it to debug a sinusoidal fringe image with good sinusoidality: at the same time, the LED array has low price, long service life and low power consumption. instrument, the equipment cost and use cost of the LED array are greatly reduced.

In another preferred embodiment of the present invention, please refer to FIG. 2 , which is a specific structural schematic diagram of a projection unit in an embodiment of the present invention.

As shown in Figure 2, the projection unit 101 also includes a light homogenizer 1016, a beam splitter 1017 and a collimator lens 1018; Meanwhile, the homogenizer 1016 is close to the illuminator 1011.

Specifically, the homogenizer 1016 makes the light intensity of the light emitted by the illuminator 1011 uniform, and reduces the divergence angle of the light emitted by the illuminator 1011; the light splitter 1017 filters the stray light contained in the light passing through the homogenizer 1016 ; The collimator lens 1018 adjusts the light passing through the beam splitter 1017 into a parallel beam.

In practical applications, since the stray light in the surrounding environment will affect the clarity of the sinusoidal fringe image, resulting in the blurring of the generated grating fringe image, therefore, the embodiment of the present invention only allows light of a fixed wavelength band to pass through by using the beam splitter 1017, so that The sinusoidal fringe image is clearer and more accurate. In addition, the placement angle of the light splitter 1017 is 45 degrees to the horizontal plane.

It can be seen that due to the poor uniformity of the LED light source, the embodiment of the present invention improves the uniformity and parallelism of the LED light source through the combination of the homogenizer 1016, the beam splitter 1017 and the collimator lens 1018, and ensures the uniformity of the generated sinusoidal fringe image. clarity.

In yet another preferred embodiment of the present invention, the device further includes: a position regulator.

The position adjuster moves the position of the sinusoidal grating sheet 1013 in a direction perpendicular to the optical path generated by the projection unit 101 to modulate the phase of the grating fringe image collected by the imaging unit 102 .

In practical applications, the position regulator can control a servo motor, which can control the sinusoidal grating sheet 1013 to move a distance of 0.1mm unit level; the sinusoidal grating sheet 1013 can be moved by the position regulator to generate four modulated grating fringe images and four Modulates the raster fringe image.

In yet another preferred embodiment of the present invention, the device further includes: a control unit.

The control unit, when the measurement object is not placed in front of the light screen 1015, uses the position adjuster to shift the phase of the sinusoidal grating in the projection unit according to the preset phase shift value, so that the imaging unit 102 collects the sinusoidal fringe image without An unmodulated grating fringe image modulated by the measurement object;

When the measurement object is placed in front of the light screen 1015, the position adjuster is used to shift the phase of the sinusoidal grating in the projection unit according to the preset phase shift value, so that the imaging unit 102 collects the sinusoidal fringe image modulated by the measurement object modulated grating fringe image.

Specifically, firstly, the sinusoidal grating sheet in the lighting unit is configured as a sinusoidal grating sheet A, and in the scene where the measurement object is not placed in front of the light screen 1015, the control unit uses the position adjuster to shift the value according to the preset phase in the Move the sinusoidal grating sheet A in the direction perpendicular to the optical path, and every time the sinusoidal grating sheet A is moved, an unmodulated grating fringe image is generated and projected on the light screen 1015; moving four times, a total of four sinusoidal grating sheet A corresponding An unmodulated grating fringe image that has not been modulated by the measurement object;

Next, in the scenario where the sinusoidal grating sheet in the lighting unit is the sinusoidal grating sheet A, and the measurement object is placed in front of the light screen 1015, the control unit uses the position adjuster to move vertically to the optical path according to the preset phase shift value. Move the sinusoidal grating sheet A in the direction, and every time the sinusoidal grating sheet A is moved, a modulated grating fringe image is generated and projected on the light screen 1015; moving four times, a total of four sinusoidal grating sheet A corresponding to the modulation of the measured object is generated. Modulated grating fringe image.

Similarly, the sinusoidal grating in the lighting unit is configured as a sinusoidal grating B. In the scene where no measurement object is placed in front of the light screen 1015, the control unit uses the position regulator to shift the value vertically to Move the sinusoidal grating sheet B in the direction of the optical path, and every time the sinusoidal grating sheet B is moved, an unmodulated grating fringe image is generated and projected on the light screen 1015; moving four times, a total of four sinusoidal grating sheet B corresponding unpassed An unmodulated grating fringe image modulated by the measurement object;

In the scene where the sinusoidal grating sheet in the lighting unit is sinusoidal grating sheet B, and the measurement object is placed in front of the light screen 1015, the control unit uses the position regulator to move in the direction perpendicular to the optical path according to the preset phase shift value The sinusoidal grating sheet B, every time the sinusoidal grating sheet B is moved, a modulated grating fringe image is generated and projected on the light screen 1015; moving four times, a total of four sinusoidal grating sheet B corresponding to the modulated modulation of the measured object is generated Raster stripe image.

It should be noted that the frequency of the sinusoidal grating sheet A and the sinusoidal grating sheet B are different, but the size and contrast are the same.

In this way, through the control unit, a total of sixteen grating fringe images are generated, specifically four unmodulated grating fringe images and four modulated grating fringe images corresponding to sinusoidal grating sheet A, and four unmodulated grating fringe images corresponding to sinusoidal grating sheet B. The fringe image and four modulated grating fringe images, so that the processing unit can calculate the size of the measuring object according to the grating fringe image.

In yet another preferred embodiment of the present invention, the imaging unit 102 collects an unmodulated grating fringe image in which the sinusoidal fringe image has not been modulated by the measurement object; collects a modulated grating fringe image in which the sinusoidal fringe image is modulated by the measurement object;

The processing unit 103 obtains the size of the measurement object by analyzing the modulated grating fringe image and the unmodulated grating fringe image collected by the imaging unit 102 by using a dual-frequency heterodyne method.

Specifically, first, the imaging unit 102 collects four unmodulated grating fringe images and four modulated grating fringe images corresponding to sinusoidal grating sheet A, and four unmodulated grating fringe images and four modulated grating fringe images corresponding to sinusoidal grating sheet B. fringe image, and send sixteen raster fringe images to the processing unit 103;

Next, the processing unit 103 collects four unmodulated grating fringe images and four modulated grating fringe images corresponding to the sinusoidal grating sheet A through the analytical imaging unit 102 to obtain the phase value A, and collects the sinusoidal grating sheet A through the analytical imaging unit 102 Four unmodulated grating fringe images and four modulated grating fringe images corresponding to B, to obtain the phase value B; use the double-frequency heterodyne method to calculate the absolute phase value according to the phase value A and phase value B; and then calculate according to the absolute phase value Measure the size of the object.

It can be seen that in the three-dimensional measuring device proposed in the embodiment of the present invention, firstly, a high-brightness light source is generated by the LED array, and then, the uniformity and parallelism of the light source are improved through the homogenizer 1016, the beam splitter 1017 and the collimating lens 1018, The final sinusoidal fringe image generated by the sinusoidal grating sheet is clear and accurate; and the position regulator can also be used to adjust the position of the sinusoidal grating sheet to generate an unmodulated grating fringe image and a modulated grating fringe image with different phases, so that the processing unit 103 can pass By analyzing the modulated grating fringe image and the unmodulated grating fringe image, the calculated size of the measured object is more accurate.

The embodiment of the invention also discloses a three-dimensional measurement method, which is applied to a three-dimensional measurement device, and the three-dimensional measurement device includes: a projection unit, an imaging unit and a processing unit.

Specifically, the projection unit includes an illuminator, a focusing lens group, a sinusoidal grating sheet, an imaging lens, and a light screen arranged in sequence; the light emitted by the illuminator passes through the focusing lens group, the sinusoidal grating sheet, and the imaging lens in sequence to generate a sinusoidal fringe image; the sinusoidal The fringe image is not modulated by the measurement object to generate an unmodulated grating fringe image, or modulated by the measurement object to generate a modulated grating fringe image, and the unmodulated grating fringe image or the modulated grating fringe image is projected onto the light screen.

The imaging unit collects the unmodulated grating fringe image or the modulated grating fringe image projected on the light screen.

The processing unit calculates the size of the measurement object according to the unmodulated grating fringe image and the modulated grating fringe image collected by the imaging unit.

Referring to Fig. 3, Fig. 3 is a kind of flowchart of the three-dimensional measurement method of the embodiment of the present invention; The three-dimensional measurement method comprises the following steps:

Step 301, using a projection unit to generate a sinusoidal fringe image.

In this step, it is necessary to adjust the brightness of the illuminator in the projection unit and the distance between the components so that the projection unit can project a clear and uniform sinusoidal fringe image with moderate brightness.

The specific process of adjusting the brightness of the illuminator in the projection unit and the placement distance between the components is: the imaging unit, specifically, the CCD camera can extract the gray scale of the sinusoidal fringe image projected on the light screen line by line, and the same frequency Standard sine function comparison, and then adjust the brightness of the illuminator in the projection unit and the spacing between components in the projection unit according to the comparison result, until the sinusoidality of the sinusoidal fringe image collected by the CCD camera meets the standard.

In this step, the light emitted by the illuminator passes through the optical path composed of the focusing lens group, the sinusoidal grating sheet and the imaging lens to generate a sinusoidal fringe image of simulated light; then, the sinusoidal fringe image is projected on the light screen.

Compared with the sinusoidal fringe image of the digital signal generated by the projector, the modulated grating fringe image generated by the sinusoidal fringe image of analog light after being modulated by the measurement object can carry richer and more accurate size information of the measurement object, thus making the final The calculated dimensions of the measured object are more precise.

Step 302 , using the imaging unit to collect a modulated grating fringe image of the sinusoidal fringe image modulated by the measurement object, and an unmodulated grating fringe image not modulated by the measurement object.

In this step, it is necessary to collect grating fringe images in two cases: one is the situation where no measurement object is placed before the light screen, and the sinusoidal fringe image is directly projected on the light screen. At this time, what is collected from the light screen is The unmodulated grating fringe image is generated without being modulated by the measurement object; the other is the situation where the measurement object is placed in front of the light screen, the sinusoidal fringe image is projected on the light screen after being reflected by the measurement object, at this time, the collected from the light screen The modulated grating fringe image is generated after being modulated by the measured object.

Step 303, using the processing unit to calculate the size of the measurement object according to the modulated grating fringe image and the unmodulated grating fringe image collected by the imaging unit.

In this step, the absolute phase value can be obtained by analyzing the unmodulated grating fringe image and the modulated grating fringe image, and then the size of the measurement object can be calculated.

It can be seen that in the three-dimensional measurement method proposed by the embodiment of the present invention, the sinusoidal fringe image generated by the projection unit is the simulated light generated by the sinusoidal grating sheet, therefore, the collected grating fringe image generated by the sinusoidal fringe image can carry more abundant And accurate size information of the measured object makes the final calculated size of the measured object more accurate.

In another preferred embodiment of the present invention, the method also includes:

A position adjuster is used to move the position of the sinusoidal grating sheet in the projection unit to change the phase of the grating fringe image collected by the imaging unit.

In yet another preferred embodiment of the present invention, before step 302, the method also includes:

When the measurement object is not placed in front of the light screen, use the position adjuster to shift the phase of the sinusoidal grating in the projection unit according to the preset phase shift value;

When placing the measurement object in front of the light screen, use the position adjuster to shift the phase of the sinusoidal grating in the projection unit according to the preset phase shift value;

Step 302 specifically includes:

An imaging unit is used to collect an unmodulated grating fringe image in which the sinusoidal fringe image has not been modulated by the measurement object;

The imaging unit is used to collect the modulated grating fringe image obtained by modulating the sinusoidal fringe image through the measurement object.

In practical application, the position regulator can be to control the servo motor.

First, configure the sinusoidal grating sheet in the lighting unit as sinusoidal grating sheet A. In the scene where no measurement object is placed in front of the light screen, use the control servo motor to move in the direction perpendicular to the optical path according to the preset phase shift value Sinusoidal grating sheet A; every time the sinusoidal grating sheet A is moved, the CCD camera collects the grating fringe image projected on the light screen once, moving four times in total, and the CCD camera can collect four unmeasured objects corresponding to the sinusoidal grating sheet A Modulated unmodulated grating fringe image.

Next, in the scene where the sinusoidal grating sheet in the lighting unit is sinusoidal grating sheet A, and the measurement object is placed in front of the light screen, use the control servo motor to move in the direction perpendicular to the optical path according to the preset phase shift value Sinusoidal grating sheet A; every time the sinusoidal grating sheet A is moved, the CCD camera collects the grating fringe image projected on the light screen once, moving four times in total, and the CCD camera can collect four sinusoidal grating sheet A corresponding to the modulation of the measured object Modulated grating fringe image.

In the same way, configure the sinusoidal grating in the lighting unit as sinusoidal grating B. In the scene where no measurement object is placed in front of the light screen, use the control servo motor to move in the direction perpendicular to the optical path according to the preset phase shift value. Move the sinusoidal grating sheet B; every time the sinusoidal grating sheet B is moved, the CCD camera collects the grating fringe image projected on the light screen once, moving four times in total, and the CCD camera can collect four unmeasured Object-modulated unmodulated grating fringe image.

Next, in the scene where the sinusoidal grating sheet in the lighting unit is sinusoidal grating sheet B, and the measurement object is placed in front of the light screen, use the control servo motor to move in the direction perpendicular to the optical path according to the preset phase shift value Sinusoidal grating sheet B; every time the sinusoidal grating sheet B is moved, the CCD camera collects the grating fringe image projected on the light screen once, moving four times in total, and the CCD camera can collect four sinusoidal grating sheet B corresponding to the modulation Modulated grating fringe image.

It should be noted that the frequency of the sinusoidal grating sheet A and the sinusoidal grating sheet B are different, but the size and contrast are the same. Moreover, in the embodiment of the present invention, there is no restriction on the execution order of moving the sinusoidal grating sheet and collecting the grating fringe image in the scene where no measurement object is placed and the scene where the measurement object is placed. That is to say, according to the execution sequence as described above, it is also possible to first move the sinusoidal grating sheet and collect the grating stripe image in the scene where the measurement object is placed, and then execute the movement of the sinusoidal grating sheet and collect the grating in the scene without the measurement object Striped image.

In this way, the CCD camera collected a total of sixteen grating fringe images, specifically four unmodulated grating fringe images and four modulated grating fringe images corresponding to sinusoidal grating sheet A, and four unmodulated grating fringe images corresponding to sinusoidal grating sheet B image and four modulated grating fringe images, in order to accurately calculate the size of the measurement object based on the grating fringe images.

In addition, in practical applications, before step 303, in order to improve the image quality of the grating fringe image, it is necessary to perform filtering processing on the collected modulated grating fringe image and the unmodulated grating fringe image.

Specifically, firstly, the filtering range is calculated according to the frequency of the grating projection, and the grating projection frequency can be obtained from the grayscale signal of the grating projection and the average value of the signal light intensity, and based on the projection frequency, the filter window is set by offsetting up and down; Then, the smoothing filter algorithm of the low-pass filter is used to analyze the grating fringe image through Fourier transform, wherein the zero frequency part of the grating fringe image is the image background, and the fundamental frequency part of the grating fringe image is the fundamental frequency of the grating image The high-frequency part of the grating fringe image is the noise interference of the image; finally, the noise in the grating fringe image is filtered out by setting the start frequency and cut-off frequency of the filter window.

In yet another preferred embodiment of the present invention, step 303 specifically includes:

The size of the measurement object is obtained by analyzing the modulated grating fringe image and the unmodulated grating fringe image collected by the imaging unit by using a double-frequency heterodyne method.

For ease of understanding, the following is an application example of calculating the size of the measurement object using a three-dimensional measurement method to illustrate the above-mentioned use of the dual-frequency heterodyne method, by analyzing the modulated grating fringe image and the unmodulated grating fringe image collected by the imaging unit. The process of dimensioning the object.

Referring to FIG. 4 , FIG. 4 is a schematic diagram of an application of the three-dimensional measuring method according to the embodiment of the present invention. In Fig. 4, the three-dimensional measurement method is applied to a three-dimensional measurement device. The three-dimensional measurement device includes an illumination unit and an imaging unit. The imaging unit is specifically a CCD camera, and the illumination unit is used to emit clear and accurate sinusoidal fringe images; The grating fringe image projected on the light screen; although the processing unit is not shown in FIG. 4 , it can be understood that the three-dimensional measuring device also includes a processing unit.

The black dotted line in Figure 4 is the measurement object, h is the height dimension of the measurement object, the measurement object is placed on the reference plane, and the xoy plane Cartesian coordinate system is established on the reference plane.

Assuming that a ray emitted from the lighting unit should be projected on point B on the reference surface, due to the existence of the measurement object, the ray is projected on point P on the measurement object. From the perspective of the CCD camera, when the measurement object is not placed, the point A on the reference surface is imaged on the point (m,n) on the CCD array. Due to the existence of the measurement object, the point P on the measurement object is imaged to the point (m, n) on the CCD array. That is to say, due to the existence of the measurement object, the information of point (m, n) on the CCD array changes from point A to point B on the reference plane.

First, the sixteen grating stripe images collected by the CCD camera are expressed in the form of formula (1):

I _i (m,n)=I ₀ (m,n)+γ(m,n)cos[φ(m,n)+α _i ], i=1,2,3,4 (1)

In formula (1), i represents the number of phase shifts, I ₀ (m,n) is the background gray level of the grating fringe image, γ(m,n) is the modulation depth of the grating fringe image, φ(m,n) is Absolute phase value, α _i is the phase value of the i-th movement; specifically, the phase values of each movement are α ₁ =0, α ₂ =π/2, α ₃ =π, α ₄ =3π/2.

Then, calculate the phase of each point in each grating fringe image:

Let α ₁ =0, α ₂ =π/2, α ₃ =π, α ₄ =3π/2, get:

In formula (3), φ′(m, n) is the main value of the phase. The main phase value φ′(m,n) is unique within a phase period, but because there are multiple grating stripes in the entire measurement space, φ′(m,n) is in a zigzag distribution, and the spatial point must be The main value of the phase is unwrapped to obtain continuous absolute phase values φ(m,n). This process is called unwrapping; using the dual-frequency heterodyne method to unwrap can avoid judgment errors when the height of the measurement object changes greatly .

Finally, according to the phase-height conversion formula, the phase information is converted into the height information of the measurement object; where the phase-height conversion formula is shown in formula (4):

In formula (4), φ _A is the absolute phase value of a certain coordinate point in the unmodulated grating fringe image, φ _B is the absolute phase value of the coordinate point in the modulated grating fringe image, and the phase φ _A and phase φ _B can be respectively Obtained from the modulated grating fringe image and the unmodulated grating fringe image; λ ₀ is the space period value of the sinusoidal grating sheet on the light screen; h is the height dimension of the measured object.

It can be seen that the three-dimensional measurement method proposed in the embodiment of the present invention can use the dual-frequency heterodyne method to calculate the size of the measurement object by analyzing the modulated grating fringe image and the unmodulated grating fringe image; thus, four-step phase shift and dual-frequency The phase solution algorithm combined with phase solution can reduce the error rate of phase solution and improve the accuracy of the calculated size of the measurement object.

It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is a relationship between these entities or operations. There is no such actual relationship or order between them. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or device. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

Each embodiment in this specification is described in a related manner, the same and similar parts of each embodiment can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, as for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and for the related parts, please refer to the part of the description of the method embodiment.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims (10)

1. A three-dimensional measuring device, characterized in that said device comprises: The projection unit includes an illuminator, a focus lens group, a sinusoidal grating sheet, an imaging lens and a light screen arranged in sequence, and both the focus lens group and the imaging lens make the sinusoidal fringe image clear and accurate; the light emitted by the illuminator , sequentially passing through the focusing lens group, the sinusoidal grating sheet and the imaging lens to generate a sinusoidal fringe image; the sinusoidal fringe image is not modulated by the measurement object to generate an unmodulated grating fringe image, or is generated after being modulated by the measurement object a modulated grating fringe image, said unmodulated grating fringe image or said modulated grating fringe image being projected onto a light screen; an imaging unit, configured to collect the unmodulated grating fringe image or the modulated grating fringe image projected on the light screen; A processing unit is configured to calculate the size of the measurement object according to the unmodulated grating fringe image and the modulated grating fringe image collected by the imaging unit. 2. The device according to claim 1, characterized in that, The focusing lens group includes plano-convex lenses, doublet lenses and plano-convex lenses arranged in sequence; The imaging lens includes a plano-convex lens. 3. The device according to claim 1 or 2, characterized in that, The projection unit further includes: a homogenizer, a light splitter and a collimator lens; the light homogenizer, the light splitter and the collimator lens are sequentially arranged between the illuminator and the focusing lens group , the homogenizer is close to the illuminator; The light homogenizer makes the light intensity of the light emitted by the illuminator uniform, and reduces the divergence angle of the light emitted by the illuminator; the light splitter reduces the stray light contained in the light passing through the light homogenizer filtering; the collimating lens adjusts the light passing through the beam splitter into a parallel beam. 4. The device of claim 3, wherein: The illuminator includes an LED array; The aperture of the homogenizer is larger than the section of the LED array. 5. The device according to claim 1, further comprising: a position regulator; The position regulator moves the position of the sinusoidal grating sheet in a direction perpendicular to the optical path generated by the projection unit, so as to modulate the phase of the grating fringe image collected by the imaging unit. 6. The device according to claim 5, further comprising: a control unit; The control unit, when the measurement object is not placed in front of the light screen, uses the position regulator to shift the phase of the sinusoidal grating in the projection unit according to the preset phase shift value, so that The imaging unit acquires an unmodulated grating fringe image in which the sinusoidal fringe image has not been modulated by the measurement object; When the measurement object is placed in front of the light screen, use the position regulator to shift the phase of the sinusoidal grating in the projection unit according to the preset phase shift value, so that the imaging unit can collect The sinusoidal fringe image is a modulated grating fringe image after being modulated by the measuring object. 7. The device of claim 6, wherein: The imaging unit collects an unmodulated grating fringe image of the sinusoidal fringe image that has not been modulated by the measurement object; collects a modulated grating fringe image of the sinusoidal fringe image modulated by the measurement object; The processing unit obtains the size of the measurement object by analyzing the modulated grating fringe image and the unmodulated grating fringe image collected by the imaging unit by using a dual-frequency heterodyne method. 8. A three-dimensional measurement method, characterized in that it is applied to a three-dimensional measurement device, and the three-dimensional measurement device includes: a projection unit, an imaging unit and a processing unit; the method includes: using the projection unit to generate a sinusoidal fringe image; Using the imaging unit to collect a modulated grating fringe image of the sinusoidal fringe image modulated by the measurement object, and an unmodulated grating fringe image not modulated by the measurement object; Using the processing unit to calculate the size of the measurement object according to the modulated grating fringe image and the unmodulated grating fringe image collected by the imaging unit. 9. The method of claim 8, further comprising: A position adjuster is used to move the position of the sinusoidal grating sheet in the projection unit to change the phase of the grating fringe image collected by the imaging unit. 10. The method according to claim 9, characterized in that, using the imaging unit, collecting the modulated grating fringe image of the sinusoidal fringe image modulated by the measurement object, and the modulated grating fringe image without the measurement object Before the step of modulating the unmodulated grating fringe image, the method further includes: When the measurement object is not placed in front of the light screen, using the position regulator to shift the phase of the sinusoidal grating in the projection unit according to a preset phase shift value; When placing the measurement object in front of the light screen, using the position regulator to shift the phase of the sinusoidal grating in the projection unit according to a preset phase shift value; The step of using the imaging unit to collect a modulated grating fringe image of the sinusoidal fringe image modulated by the measurement object, and an unmodulated grating fringe image not modulated by the measurement object includes: using the imaging unit to collect an unmodulated grating fringe image in which the sinusoidal fringe image has not been modulated by the measurement object; Using the imaging unit to collect a modulated grating fringe image of the sinusoidal fringe image modulated by the measurement object; The step of using the processing unit to calculate the size of the measurement object according to the modulated grating fringe image and the unmodulated grating fringe image collected by the imaging unit includes: The size of the measurement object is obtained by analyzing the four modulated grating fringe images and the four unmodulated grating fringe images collected by the imaging unit by using a dual-frequency heterodyne method.