JP4064120B2 - Distance measuring method and distance measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a distance measurement method and a distance measurement device, and more specifically, irradiates a measurement object with light such as a laser beam, and based on reflected light from the measurement object, the distance to the measurement object. The present invention relates to a distance measurement method and a distance measurement device suitable for distance measurement using a triangulation method for measuring distance.
[0002]
In the present specification, the “measuring object” means, for example, an opaque object having a three-dimensional spatial extent and a surface formed of a predetermined material having a rough surface. One or a plurality of colors (colors) may be applied.
[0003]
[Prior art]
Conventionally, for example, an optical distance measuring apparatus using a triangulation method is known.
[0004]
In such a distance measuring device, a laser diode that irradiates a target with a laser beam, a light receiving lens that receives reflected light from the target irradiated with the laser beam from the laser diode, and a light receiving lens. And an image sensor for forming an image of the reflected light.
[0005]
In the distance measuring device described above, the light receiving lens receives the reflected light from the object, and based on the received light waveform output from the image sensor according to the reflected light from the received object, The distance between is measured.
[0006]
Such a conventional distance measuring apparatus has a problem in that it cannot measure with high accuracy due to a temperature change of an optical system component such as a light receiving lens.
[0007]
Therefore, in the conventional distance measuring device, in order to perform highly accurate measurement, the temperature at the time of distance measurement is measured and corrected according to the temperature change, or the correction according to the temperature change is performed. Optical components to be performed are arranged separately.
[0008]
However, if the temperature measurement is performed and the correction according to the temperature change is performed as in the conventional distance measurement device, a new problem that the system of the entire distance measurement device becomes complicated is caused. In addition, if an optical component is separately provided in the distance measuring device, the configuration of the entire device becomes complicated, resulting in a new problem that the number of components and manufacturing cost increase.
[0009]
[Problems to be solved by the invention]
The present invention has been made in view of the problems of the conventional techniques as described above, and the object of the present invention is to perform high-accuracy measurement with a simple system and inexpensive distance measurement. It is an object to provide a method and a distance measuring device.
[0010]
In order to achieve the above object, the invention according to claim 1 of the present invention is directed to irradiating a measurement object placed on a turntable by light irradiating means to irradiate light from the measurement object. In a distance measurement method for performing a distance measurement process in which reflected light is imaged on an image sensor and the distance to the measurement object is measured based on the imaging position of the reflected light on the image sensor. Light irradiation that rotates on the first reference object placed on the first reference object while maintaining the same rotation angle and the same rotation angle as the rotation of the turntable under predetermined conditions. The imaging position on the image sensor that has received the laser light by the means and received the reflected light from the first reference object is made to correspond to the distance between the light irradiation means and the first reference object. Distance conversion A predetermined step in the first step, and a second reference object disposed at a position where the spot diameter of the laser beam irradiated by the light irradiation means is minimized. A second step of obtaining, as a reference imaging position, an imaging position on the image sensor that is irradiated with laser light by the light irradiating means and receives reflected light from the second reference object; The second reference object is irradiated with laser light from the light irradiating means under arbitrary conditions, and the second image formation position on the image sensor that has received the reflected light from the reference object is determined as the first reference object. By subtracting from the reference imaging position acquired in step 2, the imaging position on the image sensor that has received the reflected light from the second reference object, and the second step A third step of calculating the difference from the obtained reference image formation position, and using the difference calculated in the third step as a correction value, the correction value is connected to the image sensor in the distance conversion table. A fourth step of correcting the distance conversion table by adding to the image position; 3 The laser beam is irradiated by the light irradiation means under the above-mentioned arbitrary conditions in the step, and corrected in the fourth step from the imaging position on the image sensor that receives the reflected light from the measurement object. A fifth step of calculating a distance between the light irradiating means and the measurement object by a distance conversion table is provided.
[0011]
Therefore, according to the invention described in claim 1 of the present invention, according to the difference between the imaging position on the image sensor that receives the reflected light from the second reference object and the reference imaging position, Since the distance conversion table is corrected, even when a plastic lens is used as the light-receiving lens that receives the reflected light from the measurement object, high-precision measurement can be performed with a simple system. It can be an inexpensive method.
[0013]
Further, the present invention claims 2 The invention described in (2) is a turntable on which a measurement object is placed, and rotates while maintaining the same direction and the same rotation angle as the rotation direction of the turntable in synchronization with the rotation of the turntable, A light irradiating means for irradiating the measuring object with laser light, an image sensor for forming an image of reflected light from the measuring object irradiated with laser light from the light irradiating means, and a first reference object Under certain conditions The imaging position on the image sensor that is irradiated with laser light from the light irradiating means and receives the reflected light from the first reference object is determined between the light irradiating means and the first reference object. A distance conversion table generating means for generating a distance conversion table stored corresponding to the distance, and a second reference object arranged at a position where the spot diameter of the laser light irradiated by the light irradiation means is minimized, Under the above specified conditions Reference imaging position acquisition means for acquiring, as a reference imaging position, an imaging position on the image sensor that is irradiated with laser light from the light irradiation means and receives reflected light from the second reference object; In the second reference object Under any condition Laser light is irradiated by the light irradiation means, By subtracting the imaging position on the image sensor that has received the reflected light from the second reference object from the reference imaging position acquired by the reference imaging position acquisition means, Difference calculating means for calculating a difference between the imaging position on the image sensor that has received the reflected light from the second reference object and the reference imaging position acquired by the reference imaging position acquisition means; Correction means for correcting the distance conversion table by using the difference calculated by the difference calculation means as a correction value and adding the correction value to the image forming position on the image sensor in the distance conversion table; and the measurement On the object Under any of the above conditions The light irradiating means and the light irradiating means and the light irradiating means are corrected by the distance converting table corrected by the correcting means from the image forming position on the image sensor that receives the reflected light from the measurement object. A distance calculating means for calculating the distance to the measurement object is provided.
[0014]
Therefore, according to the third aspect of the present invention, the difference between the imaging position on the image sensor that has received the reflected light from the second reference object by the difference calculation means and the reference imaging position. Since the distance conversion table is corrected according to the difference calculated by the correction means, even when a plastic lens is used as a light receiving lens for receiving reflected light from the measurement object, High-precision measurement can be performed with a simple system, and an inexpensive apparatus can be obtained.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of a distance measuring method and a distance measuring device according to the present invention will be described in detail with reference to the accompanying drawings.
[0017]
Here, FIGS. 1 and 2 are schematic configuration perspective views showing an example of the embodiment of the distance measuring device according to the present invention. 1 is a schematic configuration perspective view when the distance measurement device is viewed from above, and FIG. 2 is a schematic configuration perspective view when the distance measurement device is viewed from below (note that the first column member 14 ( Is omitted for ease of understanding).
[0018]
FIG. 3 is an explanatory diagram of a schematic configuration centered on a laser diode when the distance measuring device is viewed from above, and FIG. 4 is a conceptual diagram of a rotating mechanism of the distance measuring device. FIG. 5 is a block diagram illustrating a control system that controls the overall operation of the distance measuring apparatus.
[0019]
The distance measuring device 10 includes a rectangular base 12 and a first column member 14 and a first column member 14 erected facing each other at a predetermined interval on one end of the base 12 on the upper surface 12a side. A two-column member 16, an upper surface member 18 that bridges the upper surface of the first column member 14 and the upper surface of the second column member 16, and a turntable base 20 disposed on the upper surface 12 a side of the base 12. 1 is formed on an upper surface 20a side of the turntable base 20 to form an XY plane in an orthogonal coordinate system defined by an X axis, a Y axis, and a Z axis orthogonal to each other and around the Z axis direction. Turn table 22 as the first rotating means, and the first column member 14 and the second column, which are rotatably arranged in the arrow A direction (clockwise direction) and the arrow B direction (counterclockwise direction), respectively. Between the member 16 1 are arranged along the axial direction (Z-axis direction) of the first pillar member 14 and the second pillar member 16, and the arrow C direction (clockwise direction) and the arrow D direction (counterclockwise direction) in FIG. A rotating support column 24 as a second rotating means that can be rotated in each direction, and a rotary support column 24 that is movably arranged in the vertical direction along the Z-axis direction via a linear motion bearing 26. A head 28 that rotates as the rotating column 24 rotates about the Z-axis direction, and a reference object 70 that is disposed on the upper surface 20a of the turntable base member 20 in the vicinity of the turntable 22 are provided. Have.
[0020]
The above-described distance measuring device 10 is controlled by the microcomputer 100 for the entire operation including drive control of a turntable motor 40, a rotary column motor 46, and a head motor 54 described later. .
[0021]
Reference numeral 34 denotes a bearing for rotatably supporting the upper end portion of the rotary column 24 on the upper surface member 18, and reference numeral 36 denotes a bearing for rotatably supporting the lower end portion of the rotary column 24 on the base 12. .
[0022]
The head 28 has a laser diode 72 as an irradiation means for irradiating a laser beam as light from the emission point 72a, a light projection lens 74 on which the laser beam irradiated from the laser diode 72 is incident, and a laser. The light receiving lens 76 that receives the reflected light from the measurement object 200 irradiated with the laser beam from the diode 72 and the diffuse reflection component of the reflected light received by the light receiving lens 76 are received, and an image of the reflected light is formed. A CCD (charge-coupled device) 78 as an image sensor for imaging is fixedly arranged in a predetermined direction. The head 28 includes a laser diode drive circuit 80 that drives the laser diode 72 and a CCD drive circuit 82 that drives the CCD 78.
[0023]
The light projecting lens 74 and the light receiving lens 76 are plastic lenses. The focal position of the projection lens 74 is set so that the spot diameter of the laser beam projected from the laser diode 72 through the projection lens 74 is minimized on the measurement surface 70a of the reference object 70. ing.
[0024]
The turntable 22 has a substantially circular upper surface 22a. In the present specification, the “rotation center of the turntable 22” is appropriately referred to as “the origin C of the turntable 22 (see FIGS. 1 and 3)”. In this embodiment, the radius r of the upper surface 22a of the turn table 22 is set to 130 mm (thus, the diameter 2r is 260 mm). The distance L1 between the origin C of the turntable 22 and the emission point 72a of the laser diode 72 of the head 28 is set to 230 mm.
[0025]
Moreover, the reference | standard target object 70 is a substantially plate-shaped body as a whole, for example, is formed with the metal and the surface is rust-proofed. The flat measurement surface 70 a is opposed to the head 28 and is fixedly disposed on the upper surface 20 a of the turntable base member 20.
[0026]
More specifically, the reference object 70 is arranged such that a distance L2 between the measurement surface 70a and the emission point 72a of the laser diode 72 of the head 28 is a predetermined distance. In this embodiment, the distance L2 between the measurement surface 70a of the reference object 70 and the emission point 72a of the laser diode 72 of the head 28 is set to 210 mm. That is, the distance L2 between the measurement surface 70a of the reference object 70 and the emission point 72a of the laser diode 72 of the head 28 is the distance between the origin C of the turntable 22 and the emission point 72a of the laser diode 72 of the head 28. It is set to be 20 mm shorter than L1.
[0027]
Next, the rotation mechanism of the turntable 22 and the rotary column 24 of the distance measuring device 10 will be described with reference to FIGS. 1 and 2. 4 It will be described with reference to the conceptual diagram of the rotation mechanism of the distance measuring device 10 shown in FIG.
[0028]
The initial positions of the turntable 22 and the rotary column 24 can be set as arbitrary positions. The rotary column 24 is attached to the rotary column 24, for example. The position of the optical axis of the laser beam emitted from the laser diode 72 of the head 28 passes through the origin C of the turntable 22, or the laser beam of the head 28 attached to the rotary column 24 For example, the optical axis of the laser beam emitted from the diode 72 may pass through the position of the center of gravity of the measuring object 200 disposed on the turn table 22.
[0029]
On the lower surface 12 b side of the base 12, a pulley 38 fixed to a rotation shaft disposed at the center of the turn table 22, a turn table motor 40 for rotating the turn table 22, A pulley 42 fixed to the rotating shaft of the table motor 40, a pulley 44 fixed to the lower end of the rotating column 24, a rotating column motor 46 for rotating the rotating column 24, and a rotating column motor 46 And a pulley 48 fixed to the rotary shaft.
[0030]
An endless belt 50 is stretched between the pulley 38 and the pulley 42, and the rotation of the rotating shaft of the turntable motor 40 is transmitted to the turntable 22. The rotation of the rotary shaft causes the turntable 22 to rotate in the direction of arrow A (clockwise direction) and in the direction of arrow B (counterclockwise direction) around the Z-axis direction.
[0031]
Further, an endless belt 52 is stretched between the pulley 44 and the pulley 48, and the rotation of the rotating shaft of the rotating column motor 46 is transmitted to the rotating column 24, and the rotating shaft of the rotating column motor 46 is rotated. The rotation support 24 rotates around the Z-axis direction in the direction of arrow C (clockwise direction) and in the direction of arrow D (counterclockwise direction).
[0032]
Here, the turn table motor 40 and the rotary column motor 46 are configured such that the turn table 22 and the rotary column 24 rotate in the same direction around the Z axis in the same direction, that is, the turn table 22 has the Z axis. When rotating in the direction of arrow A (clockwise direction) in FIG. 1 around the direction, the rotary support 24 rotates in the direction of arrow C (clockwise direction) in FIG. 1 rotates in the direction of arrow B (counterclockwise direction) in FIG. 1 around the Z-axis direction, the rotating column 24 rotates in the direction of arrow D (counterclockwise direction) in FIG. 1 around the Z-axis direction. As described above, the rotation direction and the rotation angle are controlled by the microcomputer 100.
[0033]
Further, a head motor 54 that drives the head 28 in the vertical direction along the Z-axis direction is disposed on the second column member 16. A pulley 56 is fixed to the rotating shaft of the head motor 54.
[0034]
On the other hand, a pulley 58 is rotatably disposed below the second column member 16 so as to face the pulley 56.
[0035]
An endless belt 60 that fixes a mounting portion 28a formed on the head 28 is stretched between the pulley 56 and the pulley 58, and the endless belt 60 is moved by the rotation of the rotating shaft of the motor 54. Thus, the head 28 is configured to move in the vertical direction.
[0036]
Next, FIG. 5 shows a block configuration diagram centering on a control system for controlling the entire operation of the distance measuring apparatus 10, and this control system is entirely executed by the microcomputer 100 as described above. Control of the operation is performed.
[0037]
The micro computer 100 includes a central processing unit (CPU) 102 that executes processing in accordance with a program stored in a memory 104 described later, a memory 104 that stores a program executed by the CPU 102, and a received light waveform described later under the control of the CPU 102. Random access memory (RAM) 106 in which an area as a working area when the distance measurement process is performed in the distance measuring apparatus 10 under the control of the received light waveform data storage unit 106-1 for storing data and the CPU 102 is set. And a distance data memory 108 for storing distance data described later under the control of the CPU 102.
[0038]
Here, the microcomputer 100 includes a timing signal generation circuit 110 that outputs a predetermined timing signal, and an analog / digital (A) that converts a light reception waveform signal that is an analog signal output from the CCD 78 into light reception waveform data that is a digital signal. / D) The converter 112 is connected. Accordingly, received light waveform data based on the received light waveform signal output from the CCD 78 is input to the microcomputer 100.
[0039]
Further, the CPU 102 of the distance measuring device 10 is connected to an external computer 122 via the communication circuit 120. Therefore, various data of the distance measuring device 10 is output to the computer 122 via the communication circuit 120 and can be processed by the computer 122.
[0040]
The CPU 102 outputs a measurement control signal for controlling the emission of the laser beam from the laser diode 72 and the reception of the reflected light from the CCD 78 to the timing signal generation circuit 110 at a predetermined timing.
[0041]
Further, the CPU 102 sends drive signals for driving the turn table motor 40, the rotary column motor 46, and the head motor 54 to the turn table motor 40, the rotary column motor 46, and the head motor 54 at predetermined timings. It is made to output to each of. The turn table motor 40 and the rotary column motor 46 are configured so that the turn table 22 and the rotary column 24 rotate in the same direction around the Z axis in the same direction. Is controlled by the CPU 102.
[0042]
The timing signal generation circuit 110 outputs a timing signal to each of the laser diode drive circuit 80 and the CCD drive circuit 82 at a predetermined timing according to the measurement control signal from the CPU 102. In addition, the RAM 106 and the A / D converter 112 are controlled by the timing signal generation circuit 110.
[0043]
Accordingly, the turntable 22 rotates around the Z-axis direction as the turntable motor 40 for rotating the turntable 22 is driven by a drive signal from the CPU 102. . That is, the rotation direction and the rotation angle around the Z-axis direction of the turn table 22 are controlled by the CPU 102.
[0044]
On the other hand, the head 28 rotates around the Z-axis direction of the rotary column 24 as the rotary column motor 46 for the rotary column 24 in which the head 28 is disposed is driven by a drive signal from the CPU 102. It is designed to rotate with it. The head motor 54 for moving the head 28 up and down is movable in the vertical direction along the Z-axis direction as it is driven by a drive signal from the CPU 102. Therefore, the rotation direction and rotation angle of the head 28 around the Z-axis direction, and the movement direction and movement distance along the Z-axis direction are controlled by the CPU 102.
[0045]
The laser diode 72 of the head 28 is driven by the laser diode driving circuit 80 when the timing signal output from the timing signal generating circuit 110 is input to the laser diode driving circuit 80. At this time, the laser diode 72 emits a laser beam for a predetermined time at a predetermined timing according to the timing signal.
[0046]
The CCD 78 of the head 28 includes a light receiving buffer 78 a that receives a diffuse reflection component of the reflected light received by the light receiving lens 76 and includes an electronic shutter, and a transfer buffer 78 b that transfers accumulated charges to the outside of the CCD 78. is there.
[0047]
The time during which the light receiving buffer 76a of the CCD 78 receives the reflected light (diffuse reflection component of the reflected light) from the measurement object 200, that is, the exposure time of the CCD 78 is determined by the exposure time control signal output from the timing signal generation circuit 110. It is controlled.
[0048]
The transfer buffer 78b of the CCD 78 transfers the accumulated electric charges when the light receiving buffer 78a receives the diffuse reflection component of the reflected light. Accordingly, the CCD 78 outputs a received light waveform signal, which is an analog signal, to the A / D converter 112 based on the light received by the light receiving buffer 78a.
[0049]
In the above configuration, the operation of the distance measuring apparatus 10 described above will be described with reference to FIGS.
[0050]
When the user of the distance measuring device 10 performs distance measurement on the measurement object 200 using the distance measuring device 10, the distance conversion table and the reference address are stored in a predetermined area of the memory 104 in advance. It is assumed that
[0051]
Here, the distance conversion table is for calculating the distance between the measuring object 200 and the head 28 from the received light waveform data obtained in the distance measuring device 10. For example, when the distance measuring device 10 is shipped from the factory. It is created and stored in a predetermined area of the memory 104.
[0052]
Specifically, first, a reference object 700 (see FIG. 6) formed of gypsum is placed on the upper surface 22a of the turn table 22. Further, a jig (not shown) in which a motor is provided and whose position can be specified is also placed at a predetermined position on the upper surface 22a of the turn table 22. By driving the jig with the driving force of the motor, the jig can move the reference object 700 to a predetermined position on the upper surface 22 a of the turn table 22.
[0053]
Then, along the diameter direction passing through the origin C of the turntable 22, the reference object 700 is moved from the end closest to the head 28 of the turntable 22 to the end farthest from the head 28. Are moved at predetermined intervals (see the interval W shown in FIG. 6), and the address of the CCD 78 for each movement of the interval W of the turn table 22 is sequentially stored. Note that the interval W is, for example, 5 mm.
[0054]
More specifically, each time the reference object 700 moved by the jig moves to a predetermined position for each interval W on the upper surface 22a of the turn table 22, according to the timing signal output from the timing signal generation circuit 110. The laser beam from the laser diode 72 of the head 28 is applied to the reference object 700 through the light projection lens 74.
[0055]
Then, the reflected light from the reference object 700 irradiated with the laser beam from the laser diode 72 is received by the light receiving lens 76.
[0056]
The diffuse reflection component of the reflected light received by the light receiving lens 76 in this way is a timing according to the timing signal output from the timing signal generation circuit 110, specifically, the irradiation of the laser beam from the laser diode 72. In synchronization, the light is received by the light receiving buffer 78 a of the CCD 78.
[0057]
At this time, the CCD drive circuit 82 is driven in accordance with an exposure time control signal corresponding to a preset exposure time, the electronic shutter of the CCD 78 is opened for a predetermined exposure time, and the diffuse reflection component of the reflected light is received by the light receiving buffer of the CCD 78. The light is received by 78a.
[0058]
When the light receiving buffer 78a receives the diffuse reflection component of the reflected light in this way, the accumulated charges are transferred to the outside by the transfer buffer 78b of the CCD 78, and a light receiving waveform signal is output to the A / D converter 112.
[0059]
The received light waveform signal is converted into received light waveform data by the A / D converter 112, and the received light waveform data at a predetermined position on the upper surface 22a of the turn table 22 where the reference object 700 is located is received light waveform data storage unit 106-. 1 is stored. The light reception waveform data thus obtained indicates the brightness (light reception amount) for each address of the CCD 78.
[0060]
Here, when the position of the reference object 700 is changed on the upper surface 22a of the turn table 22 by being moved by the jig, that is, when the distance between the reference object 700 and the head 28 is changed, the reflected light from the reference object 700 is reflected. The position where the diffuse reflection component is received by the light receiving buffer 78a of the CCD 78 also changes.
[0061]
For this reason, the CPU 102 calculates the center of gravity of the received light waveform indicated by the received light waveform data, and uses the CCD address S1 (see FIG. 7) corresponding to the calculated center of gravity as the imaging position on the CCD 78. The data is stored in correspondence with the position of the upper surface 22a of the turn table 22 where the reference object 700 was located when the data was obtained. Thus, a distance conversion table in which the CCD address of the CCD 78 is associated with the distance between the reference object 700 and the head 28 is generated.
[0062]
FIG. 8 shows a graph showing an example of the distance conversion table. In the graph shown in FIG. 7, on the upper surface 22 of the turn table 22 having a diameter of 260 mm, the reference object 700 is moved by 5 mm along the diameter direction passing through the origin C of the turn table 22 by a jig. It is an example of a case.
[0063]
That is, the distance “0” mm indicated on the horizontal axis of the graph corresponds to the origin C of the turntable 22, and the range of 0 <distance ≦ 130 is from the origin C of the turntable 22 to the turntable 22. Corresponding to the end closest to the head 28, the range of −130 ≦ distance <0 is from the origin C of the turntable 22 to the end of the turntable 22 farthest from the head 28. Corresponding between. Note that a blank portion between two adjacent points where the received light waveform data is actually obtained is generated by interpolation by linear interpolation.
[0064]
On the other hand, the reference address is a reference value for distance correction, is acquired under a condition that matches the condition when the distance conversion table is generated, and is stored in a predetermined area of the memory 104. Therefore, for example, when the distance measuring device 10 is shipped from the factory, if the reference address is acquired immediately after the distance converting table is generated, the distance converting table is used when the environmental temperature of the distance measuring device 10 is 28 ° C. And a reference address is acquired when the ambient temperature is 28 ° C.
[0065]
Specifically, a laser beam is projected from the laser diode 72 of the head 28 onto the surface 70 a of the reference object 70 fixedly disposed on the upper surface 20 a of the turntable base member 20. Irradiate through. Then, the reflected light from the surface 70a of the reference object 70 irradiated with the laser beam from the laser diode 72 is received by the light receiving lens 76, and the received light waveform data at the position of the reference object 70 is obtained.
[0066]
Here, the distance L2 between the measurement surface 70a of the reference object 70 and the emission point 72a of the laser diode 72 of the head 28 is 210 mm. On the measurement surface 70a of the reference object 70, the laser diode 72 projects the projection lens. The spot diameter of the laser beam projected through 74 is minimized. For this reason, the barycentric position of the light receiving waveform indicated by the light receiving waveform data obtained at the position of the reference object 70 is calculated, and the laser diode 72 is set with the CCD address corresponding to the calculated barycentric position as the imaging position on the CCD 78. Is stored as a reference address indicating a reference when the distance from the emission point 72a is 210 mm.
Since this reference address is acquired immediately after the distance conversion table is generated, for example, when a distance conversion table as shown in FIG. 8 is generated, the reference address is the distance +20 in the distance conversion table. This coincides with the CCD address S2 (see FIG. 8) of (= 230 mm (L1) -210 mm (L2)).
[0067]
In addition to the distance conversion table and the reference address, when the distance measuring apparatus 10 is shipped from the factory, for example, a laser beam emitted from the laser diode 72 of the head 28 is applied to the measurement surface 70a of the reference object 70. The swing step amount of the head 28 from the irradiation position to the position where the optical axis of the laser beam passes through the origin C of the turntable 22 is also stored in a predetermined area of the memory 104 in advance. is there.
[0068]
Then, when the user measures the measurement object 200 to be measured using the distance measuring device 10 in a state where the distance conversion table and the reference address as described above are stored in the memory 104 in advance, FIG. The distance measurement process of the distance measurement process routine shown is executed. This distance measurement processing routine is started and executed when an instruction is received from the computer 122 in a state where the distance measuring device 10 is powered on.
[0069]
When measuring the distance, the user places the measuring object 200 to be measured near the origin C on the upper surface 22 a of the turn table 22.
[0070]
On the other hand, it is assumed that the initial position of the optical axis of the laser beam emitted from the laser diode 72 of the head 28 is set to a position that passes through the origin C of the turn table 22.
[0071]
When this distance measurement processing routine is started, first, in step S902, scan parameter input processing is performed. Specifically, when the distance measurement processing routine is started in a state where the distance measuring device 10 is turned on, a user setting screen (not shown) is displayed on the screen of the display device (not shown) of the computer 122. ) Is displayed. Various parameters for measurement such as scan pitch and scan range are selected by the user using the distance measuring device 10 using an input device (not shown) of the computer 122 by selecting each column of the user setting screen. Can be set. Various parameters set in the computer 122 are input to the distance measuring device 10 via the communication circuit 120 and stored in a predetermined area of the RAM 106.
[0072]
When the process of step S902 is completed, the process proceeds to the process of step S904, and an input process of scan start instruction information is performed. When the user using the distance measuring apparatus 10 selects the start of measurement using an input device (not shown) of the computer 122, scan start instruction information for instructing the start of measurement is transmitted via the communication circuit 120. Input to the distance measuring device 10. Thereby, in the distance measuring apparatus 10, the measurement according to the scan parameter input by the process of step S902 is started.
[0073]
Subsequent to step S904, in step S906, the reference object 70 is scanned. That is, when the start of measurement is instructed by the distance measuring device 10, first, the CPU 102 controls the rotary column motor 46 in accordance with the swing step amount of the head 28 stored in a predetermined area of the memory 104 in advance. Then, the head 28 facing the origin C of the turntable 22 is rotated around the Z-axis direction (the direction of arrow C in FIG. 3). As a result, from the laser diode 72 (shown by a broken line in FIG. 3) of the head 28 that faces the reference object 70, a laser beam is transmitted through the projection lens 74 to the reference object. 70 is irradiated.
[0074]
The reflected light from the surface 70 a of the reference object 70 irradiated with the laser beam from the laser diode 72 is received by the light receiving lens 76. The diffuse reflection component of the reflected light received by the light receiving lens 76 is received by the light receiving buffer 78a of the CCD 78, the accumulated charge is transferred to the outside by the transfer buffer 78b of the CCD 78, and the received light waveform signal is converted to the A / D converter 112. Is output.
[0075]
The received light waveform signal is converted into received light waveform data by the A / D converter 112, and received light waveform data at the position of the reference object 70 after the start of measurement and before the start of measurement is obtained.
[0076]
When the process of step S906 ends, the process proceeds to step S908, the difference from the reference address is calculated, and the correction value is determined. More specifically, the barycentric position of the received light waveform indicated by the received light waveform data is calculated from the received light waveform data at the position of the reference object 70 after the measurement start instruction obtained by the process of step S906. Then, the difference between the CCD address corresponding to the calculated center of gravity position and the reference address is calculated.
[0077]
If the CCD address corresponding to the barycentric position of the received light waveform data at the position of the reference object 70 after the measurement start instruction coincides with the reference address, the light reception at the position of the reference object 70 after the measurement start instruction in step S906. The conditions when the waveform data is obtained, that is, the temperature of the external environment where the distance measuring device 10 is currently installed, etc. are the same as when the reference address was acquired and have not changed.
[0078]
That is, it is not necessary to consider the expansion and contraction of the plastic light receiving lens 76 due to the temperature change, and the CCD address and the reference address corresponding to the position of the center of the received light waveform data at the position of the reference object 70 after the measurement start instruction is given. The difference is “0”, and the correction value = 0.
[0079]
On the other hand, if the CCD address corresponding to the barycentric position of the received light waveform data at the position of the reference object 70 after the measurement start instruction does not coincide with the reference address, the reference object 70 after the measurement start instruction in step S906. That is, the condition when the received light waveform data at the position is obtained, that is, the external environment such as the temperature at which the distance measuring device 10 is disposed, has changed without coincident with the acquisition of the reference address.
[0080]
That is, it is necessary to consider the expansion and contraction of the plastic light receiving lens 76 accompanying the temperature change, and the difference between the address of the barycentric position of the received light waveform data at the position of the reference object 70 after the measurement start instruction and the reference address are calculated. Calculate the correction value. In this case, the correction value ≠ 0.
[0081]
When the process of step S908 ends, the process proceeds to the process of step S910, and the measurement object 200 placed on the turn table 22 is scanned.
[0082]
First, the CPU 102 controls the rotary column motor 46 in accordance with the head swing amount of the head 28 stored in a predetermined area of the memory 104 in advance, so that the head 28 facing the reference object 70 is moved to Z. Rotate in the axial direction (in the direction of arrow D in FIG. 3) and face the origin C of the turntable 22.
[0083]
Here, the measurement surface of the measurement object 200 (see FIG. 5) arranged on the turn table 22 is measured with the measurement point P0, the measurement point P1, the measurement point P3,..., The measurement point Pm-1, and the measurement point Pm (however, , “M” is a positive integer indicating the total number of measurement points.) If measurement is performed every time, and if “angle θ = 1 °” is set, measurement points P0 to Pm are measured. The distance is measured at each measurement point where the angle on the measurement surface is changed by 1 °.
[0084]
At this time, the rotation of the measuring object 200 around the Z-axis direction accompanying the rotation of the turntable 22 by driving the turntable motor 40, the rotating column motor 46 and the head motor 54 according to the drive signal of the CPU 102. The head 28 is rotated around the Z-axis direction in such a manner that the optical axis of the laser beam emitted from the laser diode 72 maintains the same direction and the same rotation angle as the measurement object 200. Rotate to
[0085]
Thereby, the region of the measurement surface of the measuring object 200 irradiated with the laser beam from the laser diode 72 can be orthogonal to the optical axis of the laser beam irradiated by the laser diode 72, and the measurement is performed. It is designed to improve the accuracy.
[0086]
The distance measurement performed while changing the turn table 22 and the head 28 by a predetermined angle θ is repeated while changing the vertical height of the head 28 in the Z-axis direction. Measure the distance of the measurement surface.
[0087]
Then, a laser beam is emitted from the laser diode 72 of the head 28 for each measurement point on the measurement surface of the measurement object 200 arranged on the turn table 22, and the received waveform data at each measurement point is received waveform data. It is stored in the storage unit 106-1.
[0088]
Subsequent to step S910, distance data calculation processing is performed in step S912. In this distance data calculation process, the distance between each measurement point of the measuring object 200 and the head 28 is shown from the received light waveform data for each measurement point stored in the received light waveform data storage unit 106-1 in step S910. Distance data is calculated.
[0089]
The distance data is calculated from the received light waveform data by calculating the peak position of the received light waveform indicated by the received light waveform data, and using the distance conversion table using the CCD address corresponding to the calculated peak position as the imaging position on the CCD 78. Done.
[0090]
Here, when the correction value = 0 in step S908, that is, when the CCD address corresponding to the barycentric position of the received light waveform data at the position of the reference object 70 after the measurement start instruction coincides with the reference address. Calculates distance data using a distance conversion table created at the time of factory shipment of the distance measuring device 10 and stored in a predetermined area of the memory 104.
[0091]
For example, when the distance conversion table shown in FIG. 8 is created when the distance measuring apparatus 10 is shipped from the factory and stored in a predetermined area of the memory 104, the CCD address corresponding to the calculated peak position of the received light waveform is “41000. ", The distance is +54 mm. That is, the distance between each measurement point of the measurement object 200 from which the received light waveform data is obtained and the head 28 is 176 mm (= 230 mm (L1) −54 mm).
[0092]
On the other hand, if the correction value is not 0 in step S908, that is, if the CCD address corresponding to the barycentric position of the received light waveform data at the position of the reference object 70 after the measurement start instruction does not match the reference address. The distance conversion table created at the time of factory shipment of the distance measuring device 10 and stored in a predetermined area of the memory 104 is corrected with the correction value, and the distance data is calculated using the corrected distance conversion table.
[0093]
Specifically, for example, the CCD address corresponding to the barycentric position of the received light waveform data at the position of the reference object 70 after the measurement start instruction obtained in step S906 is “43281”, and the reference address is “43781”. If there is, the difference between the address “43281” of the barycentric position of the received light waveform data at the position of the reference object 70 after the measurement start instruction and the reference address “43781” is +500 (= 43781-43281) by the process of step S908. Is determined as a correction value.
[0094]
That is, the address of the distance conversion table created at the time of shipment of the distance measuring apparatus 10 and stored in a predetermined area of the memory 104 is shifted by the correction value = + 500 minutes (see the broken line in FIG. 10). As a result, if the CCD address corresponding to the calculated peak position of the received light waveform is “41000”, the distance is +58 mm. That is, the distance between each measurement point of the measurement object 200 from which the received light waveform data is obtained and the head 28 is 172 mm (= 230 mm (L1) −58 mm).
[0095]
The calculated distance data is stored in the distance data memory 108. Further, the distance data stored in the distance data memory 108 is output to the computer 122 via the communication circuit 120, and this distance measurement processing routine is terminated.
[0096]
As described above, in the distance measurement device 10 including an example of the embodiment of the distance measurement method and the distance measurement device according to the present invention, the center of gravity of the received light waveform data at the position of the reference object 70 after the measurement start instruction is set. When the corresponding CCD address and the reference address do not match, a correction value is calculated, and the distance conversion table generated using the reference object 700 is corrected, so high-precision measurement can be performed with a simple system. This can be done and an inexpensive device.
[0097]
That is, according to the distance measuring method and the distance measuring device according to the present invention, the plastic light receiving lens 76 is disposed in the distance measuring device 10, but the temperature at the time of distance measurement is measured and corrected according to the temperature change. Thus, a highly accurate measurement result can be obtained without separately arranging optical components that perform correction according to temperature changes.
[0098]
Further, according to the distance measuring method and the distance measuring device of the present invention, the inexpensive plastic light receiving lens 76 is used without changing the plastic light receiving lens to an expensive glass which is hardly affected by temperature. Since a highly accurate measurement result can be obtained, the entire apparatus can be made inexpensive.
[0099]
Furthermore, according to the distance measuring method and the distance measuring device according to the present invention, it is not limited to the case where the plastic light receiving lens expands or contracts with a change in temperature, for example, an external environment other than temperature such as humidity, or Even when various conditions such as temperature changes of optical system parts such as a projection lens and a lens barrel change, a highly accurate measurement result can be obtained.
[0100]
In addition, the above-described embodiment has the following (1) to ( 6 It may be modified as described in FIG.
[0101]
(1) In the above-described embodiment, the laser diode 72 is used as the light irradiating means. However, the present invention is not limited to this, and for example, various types such as a multi-mode laser oscillator. A laser oscillator, a lamp, or the like may be used.
[0102]
(2) In the above-described embodiment, the CCD 78 is used as the image sensor. However, the present invention is not limited to this, and various image sensors may be used as appropriate.
[0103]
(3) In the above-described embodiment, the case of “angle θ = 1 °” has been described when scanning the measuring object 200. However, the present invention is not limited to this, and the angle θ is arbitrary. The angle can be set. Also, head 28 and turn Te Of course, the driving method and driving direction of the table 22 are not limited to the above-described embodiment, and are appropriately changed so that all the measurement points can be measured according to the type of the measurement object 200 and the like. May be.
[0104]
(4) In the above embodiment, the received light waveform data and the distance data are So Each of them is stored in the received light waveform data storage unit 106-1 and the distance data memory 108. However, the present invention is not limited to this. Whether the processing is performed inside or outside may be appropriately changed.
[0105]
(5) In the above-described embodiment, a distance conversion table is generated using the reference object 700 formed of gypsum, and the reference object 70 formed of metal and subjected to rust prevention processing on the surface is used. However, this is not limited to this, and the reference object for generating the distance conversion table and the reference object for acquiring the reference address are the materials. May be changed as appropriate, and the arrangement position and the like may be changed in accordance with the overall dimensions of the apparatus.
[0108]
( 6 ) The above embodiment and the above (1) to ( 5 ) May be combined as appropriate.
[0109]
【The invention's effect】
Since the present invention is configured as described above, it has an excellent effect that a highly accurate measurement can be performed with a simple system and an inexpensive distance measuring method and distance measuring apparatus can be provided. Play.
[Brief description of the drawings]
FIG. 1 is a schematic configuration perspective view showing an example of an embodiment of a distance measurement device according to the present invention, and is a schematic configuration perspective view when the distance measurement device is viewed from above.
FIG. 2 is a schematic configuration perspective view showing an example of an embodiment of a distance measurement device according to the present invention, and is a schematic configuration perspective view when the distance measurement device is viewed from below. The first pillar member is omitted for easy understanding.
FIG. 3 is a schematic structural explanatory view mainly showing a laser diode when the distance measuring device according to the present invention is viewed from above.
FIG. 4 is a conceptual diagram of a rotation mechanism of a distance measuring device according to the present invention.
FIG. 5 is a block diagram mainly showing a control system for controlling the overall operation of the distance measuring apparatus according to the present invention.
FIG. 6 is an explanatory view mainly showing a laser diode and a CCD of a distance measuring device according to the present invention.
FIG. 7 is a graph showing an example of a received light waveform indicated by received light waveform data.
FIG. 8 is a graph showing an example of a distance conversion table.
FIG. 9 is a flowchart of a distance measurement processing routine of the distance measuring device according to the present invention.
FIG. 10 is a graph showing another example of the distance conversion table.
[Explanation of symbols]
10 Distance measuring device
12 base
12a Top surface of base
14 First pillar member
16 Second pillar member
18 Top member
20 Turntable base
20a Top surface of turntable base
22 Turntable
24 Rotating prop
26 Linear motion bearing
28 heads
28a Mounting part
34, 36 Bearing
38, 42, 44, 48, 56, 58 Pulley
40 Turntable motor
46 Rotating prop motor
50, 52, 60 Endless belt
54 motor
70 Reference object
70a Measuring surface
72 Laser diode
72a Exit point
74 Projection lens
76 Receiving lens
78 CCD
78a Light receiving buffer
78b Transfer buffer
80 Laser diode drive circuit
82 CCD drive circuit
100 micro computer
102 Central control unit (CPU)
104 memory
106 Random access memory (RAM)
106-1 light receiving waveform data storage unit
108 Distance data memory
110 Timing Signal Generation Circuit
112 Analog / Digital (A / D) Converter
120 communication circuit
122 computer
200 Measurement object
700 Reference object

Claims (2)

Light is irradiated onto the measurement object placed on the turntable by the light irradiation means, and the reflected light from the measurement object is imaged on the image sensor, and the reflected light on the image sensor is In a distance measurement method for performing a distance measurement process for measuring a distance from the measurement object based on an imaging position,
The first reference object placed on the turntable is rotated while maintaining the same rotation angle and the same rotation angle as the rotation of the turntable under predetermined conditions in synchronization with the rotation of the turntable. The imaging position on the image sensor that has received the laser light by the light irradiating means and received the reflected light from the first reference object is the distance between the light irradiating means and the first reference object. A first step of generating a distance conversion table stored corresponding to
Laser light is emitted from the light irradiating means to the second reference object arranged at a position where the spot diameter of the laser light irradiated by the light irradiating means is minimized under the predetermined condition in the first step. A second step of obtaining, as a reference imaging position, an imaging position on the image sensor that has been irradiated and received reflected light from the second reference object;
The second reference object is irradiated with laser light from the light irradiation means under arbitrary conditions, and the second image formation position on the image sensor that has received the reflected light from the reference object is determined as the first reference object. By subtracting from the reference imaging position acquired in step 2, the imaging position on the image sensor that has received the reflected light from the second reference object and acquired in the second step A third step of calculating a difference from the reference imaging position;
A fourth step of correcting the distance conversion table by adding the correction value calculated as the correction value in the third step to an image forming position on the image sensor in the distance conversion table;
The measurement object is irradiated with laser light from the light irradiation means under the arbitrary conditions in the third step, and is reflected from the imaging position on the image sensor that receives reflected light from the measurement object. 5. A distance measuring method comprising: a fifth step of calculating a distance between the light irradiation means and the measurement object using a distance conversion table corrected in step 4. A turntable on which the object to be measured is placed;
A light irradiating means for irradiating a laser beam to the object to be measured;
An image sensor that forms an image of reflected light from the measurement object irradiated with laser light from the light irradiation means;
The first reference object is irradiated with laser light from the light irradiation means under a predetermined condition, and the image formation position on the image sensor that has received the reflected light from the first reference object is defined as the light. Distance conversion table generating means for generating a distance conversion table stored in correspondence with the distance between the irradiation means and the first reference object;
The second reference object arranged at a position where the spot diameter of the laser beam irradiated by the light irradiation unit is minimized is irradiated with the laser beam by the light irradiation unit under the predetermined condition . Reference imaging position acquisition means for acquiring, as a reference imaging position, an imaging position on the image sensor that has received reflected light from the reference object;
The second reference object is irradiated with laser light from the light irradiation means under an arbitrary condition, and the imaging position on the image sensor that receives the reflected light from the second reference object is the reference position. By subtracting from the reference imaging position acquired by the imaging position acquisition means, the imaging position on the image sensor that has received the reflected light from the second reference object, and the acquisition of the reference imaging position A difference calculating means for calculating a difference from the reference imaging position acquired by the means;
Correction means for correcting the distance conversion table by adding the correction value calculated by the difference calculation means as a correction value and adding the correction value to the imaging position on the image sensor in the distance conversion table;
The measurement object is irradiated with laser light from the light irradiation unit under the arbitrary conditions, and corrected by the correction unit from the imaging position on the image sensor that receives the reflected light from the measurement object. A distance measuring device comprising: a distance calculating unit that calculates a distance between the light irradiating unit and the measurement object by the distance conversion table.

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