JP3928350B2 - Data output method in displacement sensor and displacement sensor using the method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical displacement sensor that measures the distance to a measurement object using reflected light when the measurement object is irradiated with light. In particular, the displacement sensor of this type is supported on a plane. The present invention relates to a method for outputting the result of discrimination processing using the measurement result when measuring the measured object.
[0002]
[Prior art]
A conventional optical displacement sensor includes a sensor head in which a light source such as a laser diode and a light receiving unit such as a PSD and a CCD are incorporated, a controller that processes a signal from the sensor head, and the like. The controller processes the signal from the light receiving unit and measures the position of the reflected light image on the light receiving surface, and then measures the distance from the sensor head to the observation target based on the principle of triangulation.
[0003]
Some sensors of this type have a built-in function for outputting the measurement result as it is and replacing the output of a predetermined measurement value with “zero”. According to this “zero reset function”, for example, when measuring the height of a measurement object supported on a flat surface, the result obtained by measuring a non-defective model is used as a reference measurement value, and the output of this measurement result is output. By resetting to zero, the subsequent measurement result can be output as an excess or deficiency with respect to the reference measurement value, and the suitability of the height of each measurement object can be easily determined.
[0004]
Furthermore, this type of sensor has a function for determining the suitability of the length of each measurement object by comparing the excess / deficiency with respect to the reference measurement value with a predetermined determination reference value, and a function for outputting the determination result. May be set.
For example, when using the above function to check the suitability of the product size in a factory production line, each product is sequentially guided onto a plane such as an inspection stage, and the part to be measured is installed vertically. Measure from above. When the length of the part installed in the vertical direction is not appropriate, the excess / deficiency with respect to the reference measurement value is a value greatly deviated from the determination reference, and therefore, the suitability of the size can be automatically determined.
[0005]
[Problems to be solved by the invention]
In the conventional process for determining the suitability of the length of a measurement object, if there are multiple types of measurement objects and the size of each measurement object differs for each type, A process of measuring the model and resetting the measured value to zero must be performed . However, in such a method, it is necessary to prepare a model for each species, which causes a problem that the processing becomes complicated.
[0006]
The present invention has been made paying attention to the above-described problems , and enables the process of determining the appropriateness of the length of the measurement object to be executed without performing the setting process using the model corresponding to the measurement object. Accordingly, it is an object of the present invention to greatly reduce the labor required for setting for the suitability determination process.
[0007]
[Means for Solving the Problems]
In this invention, the measurement object on the support surface is irradiated with light from the direction toward the support surface, and the reflected light from the measurement object is received by a light receiving means having a light receiving surface of a predetermined size, and the light reception In the displacement sensor that measures the distance to the measurement object based on the position of the reflected light image on the surface, the measurement value when measuring the object whose distance from the support surface to the reflection position of the light is known as the reference measurement value, The known distance is stored as an offset value in the memory, and the measurement value obtained for the measurement object is converted into data indicating the distance from the support surface to the light reflection position based on the reference measurement value and the offset value. I converted it.
[0008]
The light is emitted from a light source such as a laser diode. The light receiving means includes a light receiving surface by a PSD or a one-dimensional or two-dimensional light receiving element, and is installed so as to receive reflected light from a measurement object within a predetermined distance range from the light receiving surface. Since the position of the reflected light image on the light receiving surface varies depending on the distance between the sensor head and the light reflection position, the distance from the sensor head to the measurement object can be obtained by the principle of triangulation.
[0009]
The “support surface” that supports the measurement object is a horizontal plane that supports the measurement object at a lower position in an optimal mode. However, for example, when the measurement object is in contact with a vertical wall surface, the support surface may be a flat surface arranged along the vertical direction. In addition, if the measurement object is fixedly supported at a specific position by other means (for example, gripping means), a virtual plane in contact with the measurement object can be considered as a “support surface”.
[0010]
The “light reflection position” refers to a position where light from a light source is irradiated on the measurement object and reflected to the light receiving unit.
The “distance from the support surface to the light reflection position” can be rephrased as the length of the measurement object in the direction orthogonal to the support surface. For example, when the measurement object is supported by a horizontal plane at the lower position, the distance corresponds to the height of the measurement object. However, if the portion of the measurement object facing the light source is not flat, the length may not be the maximum length.
[0011]
According to the present invention, the measurement value D0 obtained for the object of known size is set as the reference measurement value, and the distance H0 from the support surface to the light reflection position on the object is set as the offset value. In order to convert the measurement value D obtained for the measurement object into the distance from the support surface to the light reflection position, a value obtained by subtracting the measurement value D from the reference measurement value D0 (if D0 <D, a negative value is used). The offset value H0 may be added to the above. The offset value H0 is data calculated from a known size of the object, and is input by the user before or after the measurement process for the object.
[0012]
In general, in a displacement sensor, theoretically, the length of a measurement object can be obtained by a method in which a measurement value is subtracted from a distance between an optical system and a support surface. However, the positional relationship between the support surface and the optical system varies depending on the installation conditions of the sensor, and the support surface may be located farther than the sensor's measurable area. Have difficulty.
In contrast, according to the present invention, regardless of the positional relationship between the optical system and the support surface can be easily obtained the length of the measurement object. In addition, since it is only necessary to set the reference measurement value and the offset value using an arbitrary object having a known size, measurement can be performed without any trouble even when a model of the measurement object cannot be prepared.
[0013]
Further in the present invention, with the measurement object, the numerical value indicating the proper distance from the support surface to the reflection position of the light is stored in memory as a criterion value, the light from the support surface obtained by the conversion process Data indicating the distance to the reflection position is compared with a determination reference value corresponding to the measurement object, and the comparison result is output.
[0014]
The determination reference value is a numerical value based on a good size of the measurement object. For example, a numerical value input by the user is received inside the sensor and registered in the memory. Therefore, in the above method, after the measurement value obtained for the measurement object is converted into data indicating the length of the measurement object, the converted data is compared with the determination reference value in the memory. The suitability of the length is determined.
Note that the determination reference value is not limited to one numerical value, and an upper limit value and a lower limit value that indicate a range of length that can be determined as non-defective products may be set.
[0015]
According to the above method, if the reference measurement value and the offset value are set using an arbitrary object having a known size prior to measurement, the numerical value indicating the determination reference value is stored in the memory for the measurement object. Just enter it. Therefore, when determining whether or not the length is appropriate, even if the type of the measurement object is changed, it is possible to cope with it by simply resetting the determination reference value.
[0016]
Further, when there are a plurality of types of measurement objects, a numerical value indicating an appropriate distance from the support surface to the light reflection position is stored in the memory as a determination reference value for each measurement object, and the conversion process is performed. Data indicating the distance from the support surface to the reflection position of the light obtained by the above may be compared with a determination reference value corresponding to the measurement object, and the comparison result may be output. In this case, when the user selects the determination reference value corresponding to the measurement target object being processed, the determination process based on the selected determination reference value may be executed. In this case, it is only necessary to reselect the determination reference value, and the setting process is further simplified.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows the appearance of an optical displacement sensor according to one embodiment of the present invention.
This displacement sensor has a configuration in which a sensor head 1, a monitor 3, a console 4 and the like are connected to a controller 2 which is a control main body by a cable. The sensor head 1 incorporates a light source by a laser diode, a light receiving part by a two-dimensionally arranged CCD, etc., and irradiates the measurement object 8 with a laser beam and synchronizes with this beam irradiation. A video signal indicating a light receiving state of the reflected beam from 8 is generated and output to the controller 2.
[0018]
The controller 2 takes in the image generated by the sensor head 1 and measures the distance from the sensor head 1 to the measurement object 8 based on the position of the reflected light image on the image. Further, the controller 2 converts the measurement value into data indicating the height of the measurement object 8 (hereinafter referred to as “height data”) and compares it with a predetermined determination reference value, as will be described in detail later. Then, it is determined whether or not the height of the measurement object 8 is appropriate, and a signal indicating the determination result is output.
[0019]
The monitor 3 receives the image generated by the light receiving unit from the controller 2, the height data, and the result of determining whether or not the height is appropriate, and displays these data as well as the input of a GUI system 17 to be described later. Functions as an output unit. The console 4 is used for inputting various setting values to the GUI system 17.
[0020]
FIG. 2 shows the configuration of the optical system of the sensor head 1 together with the principle of measurement processing.
In FIG. 2A, 5 indicates a laser diode as a light source, 6 indicates a two-dimensional CCD of the light receiving unit, and 7 indicates a light receiving lens. The light emitted from the laser diode 5 is applied to the upper surface of the measurement object 8 via a slit (not shown) or a light projection lens.
[0021]
A part of the reflected light from the measurement object 8 is guided to the two-dimensional CCD 6 through the light receiving lens 7, and the imaging position of the reflected light on the two-dimensional CCD 6 is the height of the measurement object 8. It depends on the position.
[0022]
2 (2) is an image obtained when the measurement object 8 is at the position A in FIG. 2 (1), and FIG. 2 (3) is the position at which the measurement object 8 is B in FIG. 2 (2). The reflected light images 9 of the laser beams appear respectively.
2 (2) and 2 (3), the left end and the right end of the image respectively correspond to the upper limit and the lower limit of the measurable area S described later. In this measurable region, the reflected light image 9 moves to the left as the measurement object 8 approaches the sensor head 1, and the reflected light image 9 moves to the right as the measurement object 8 moves away from the sensor head 1. Therefore, by applying the coordinate position of the reflected light image on the image to the principle of triangulation, the distance from the sensor head 1 to the measurement object 8 (specifically, for example, from the laser diode 5 to the upper surface of the measurement object 8). ) Is calculated.
[0023]
FIG. 3 shows the configuration of the controller 2.
The controller 2 of this embodiment is mainly composed of a control unit 10 by a microcomputer, and in addition, an amplifier circuit 11 for receiving a video signal from the sensor head 1, an A / D converter 12 for digitally converting the video signal, an external device. 15, an I / O interface 13 for exchanging data with the D / A converter 14 and a D / A converter 14 are incorporated.
[0024]
In the control unit 10, a measurement / control system 16 for performing main processing and a GUI system 17 for developing a user interface on the screen of the monitor 3 are set.
The measurement / control system 16 transmits a timing signal to the sensor head 1 to drive the laser diode 5 and the two-dimensional CCD 6 in synchronization with each other, and also includes a digital signal including the reflected light image 9 by the A / D converter 12. An image is captured, and the above-described measurement processing and height suitability determination processing are executed.
[0025]
The result of the height suitability determination process is output as a digital signal from the I / O interface 13 to the external device 15. The height data is similarly output as a digital signal and is also output to the external device 15 in a form converted to an analog signal by the D / A converter 14.
Note that a programmable controller, a personal computer, or the like is used as the external device 15.
[0026]
The GUI system 17 is mainly used for inputting appropriate height data of the measurement object 8 and inputting an offset value for obtaining the height data.
The offset value is input when a model having a known height is measured. For example, when a predetermined operation is performed by the console 4 when the measurement result of the model is displayed on the monitor 3, an offset value input window is displayed on the monitor 3. In this window, when a known height of the model is input as an offset value by operating the console 4, the input offset value is referred to as a measured value (hereinafter referred to as “reference measured value”) obtained for the model. ) And a memory (not shown) in the control unit 10.
[0027]
On the other hand, appropriate height data is set so that it can be individually input for each of the plurality of types of measurement objects 8. The input height data is registered in the memory as a determination reference value for the height appropriateness determination process.
When performing the inspection, a determination reference value corresponding to the inspection target is selected from the registered determination reference values. In addition, every time the object is changed during the inspection, the user needs to change the setting of the determination reference value via the GUI system 17.
[0028]
FIG. 4 schematically shows a method for obtaining the height data.
P in the figure is the above-described model, D0 indicates the reference measurement value, and H0 indicates the known height of the model input as an offset value. Further, S in the figure is a measurable area by the optical system shown in FIG. 2, that is, an area where reflected light can enter the two-dimensional CCD 6.
[0029]
The control / measurement system 16 applies the distances D1, D2 from the sensor head 1 to the measurement objects 81, 82 based on the principle described above for each measurement object (indicated by reference numerals 81, 82 in the figure). Is calculated. Further, the control / measurement system 16 calculates values d1 and d2 obtained by subtracting the distances D1 and D2 calculated from the reference measurement value D0, and the subtraction results d1 and d2 (d1 <0, d2> 0 are obtained). Is added to the offset value H0 to calculate the heights H1 and H2 of the measurement objects 81 and 82, respectively.
[0030]
In FIG. 4, if it is assumed that the measurement objects 81 and 82 are different types of workpieces, the determination reference values for determining appropriateness of the heights of the measurement objects 81 and 82 are different. According to the method of replacing the reference measurement value with zero using the conventional zero reset function, each time the measurement object is changed, the reference measurement value is set again for the new measurement object using a non-defective model. The value corresponding to the value needs to be reset to zero.
[0031]
On the other hand, in this embodiment, when shifting from the discrimination process for the measurement object 81 to the discrimination process for the measurement object 82, it is not necessary to perform measurement processing by a new model and resetting of the offset value. Since it is only necessary to change the value, the inspection efficiency can be greatly improved. Even if the model P used for setting the offset value is a model of a workpiece of a different type from the measurement objects 81 and 82, there is no problem as long as the height is known.
[0032]
In this way, once an offset value is registered using an arbitrary model without being bound by the measurement object, the height suitability determination process can be performed by simply changing the threshold value setting according to the measurement object. You can continue.
Moreover, since the height data of each measurement object can be displayed on the monitor 3, the user can easily grasp the specific height of the measurement object, and the convenience of the sensor is greatly improved. improves.
[0034]
【The invention's effect】
According to the present invention, in the optical displacement sensor, when determining the suitability of the length of the measurement object using the measurement value, the appropriate distance from the support surface to the light reflection position is determined for the measurement object. By registering as a value, it is not necessary to perform setting processing by measuring a non-defective model, and the labor required for this type of setting processing can be greatly reduced. Further, when the type of the measurement object changes, it can be dealt with by simply resetting the determination reference value, and the process can be promptly shifted to the next determination process, so that the processing efficiency can be greatly improved.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an appearance of an optical displacement sensor according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a configuration of an optical system of a sensor and a principle of measurement processing.
FIG. 3 is a block diagram illustrating a configuration of a controller.
FIG. 4 is an explanatory diagram showing a method for obtaining height data.
[Explanation of symbols]
1 Sensor head 2 Controller 3 Monitor 4 Console 5 Laser diode 6 2D CCD
10 Control unit 15 External device

Claims (4)

The measurement object on the support surface is irradiated with light from the direction toward the support surface, and the reflected light from the measurement object is received by a light receiving means having a light receiving surface of a predetermined size, and reflected on the light reception surface. In a displacement sensor that measures the distance to the measurement object based on the position of the optical image,
The measured value when the distance from the support surface to the reflection position of the light is measured is measured as a reference measured value, the known distance is stored as an offset value in the memory, and the measurement object A numerical value indicating an appropriate distance from the support surface to the light reflection position is stored in the memory as a determination reference value;
After the measurement value obtained for the measurement object is converted into data indicating the distance from the support surface to the light reflection position based on the reference measurement value and the offset value, the converted data is compared with the determination reference value. And outputting the comparison result. The measurement object on the support surface is irradiated with light from the direction toward the support surface, and the reflected light from the measurement object is received by a light receiving means having a light receiving surface of a predetermined size, and reflected on the light reception surface. In a displacement sensor that measures the distance to the measurement object based on the position of the optical image,
A measured value when measuring an object with a known distance from the support surface to a light reflection position is used as a reference measured value, and the known distance is stored as an offset value in a memory, and a plurality of types of measurement objects For each object, a numerical value indicating an appropriate distance from the support surface to the light reflection position is stored in the memory as a determination reference value,
After the measurement value obtained for the measurement object is converted into data indicating the distance from the support surface to the light reflection position based on the reference measurement value and the offset value, the converted data is determined corresponding to the measurement object. An output method for a displacement sensor, wherein the comparison result is output by comparing with a reference value. The measurement object on the support surface is irradiated with light from the direction toward the support surface, and the reflected light from the measurement object is received by a light receiving means having a light receiving surface of a predetermined size, and reflected on the light reception surface. A displacement sensor that measures the distance to the measurement object based on the position of the optical image,
An input means for receiving an input of a numerical value indicating a distance from the support surface to the light reflection position of the object when measuring an object having a known size;
Registration means for storing each of the input known distance as an offset value in a memory, with a measurement value obtained when the object having a known size is measured as a reference measurement value;
Conversion processing means for converting the measurement value obtained for the measurement object into data indicating a distance from the support surface to a light reflection position using the reference measurement value and the offset value;
A determination criterion setting unit that receives an input of a numerical value indicating an appropriate distance from the support surface to the light reflection position for the measurement object, and stores the numerical value in a memory as a determination reference value;
For the measurement object, comparison means for comparing the data after the conversion process with the determination reference value;
A displacement sensor comprising output means for outputting a comparison result by the comparison means. The measurement object on the support surface is irradiated with light from the direction toward the support surface, and the reflected light from the measurement object is received by a light receiving means having a light receiving surface of a predetermined size, and reflected on the light reception surface. A displacement sensor that measures the distance to the measurement object based on the position of the optical image,
An input means for receiving an input of a numerical value indicating a distance from the support surface to the light reflection position of the object when measuring an object having a known size;
Registration means for storing each of the input known distance as an offset value in a memory, with a measurement value obtained when the object having a known size is measured as a reference measurement value;
Conversion processing means for converting the measurement value obtained for the measurement object into data indicating a distance from the support surface to a light reflection position using the reference measurement value and the offset value;
For a plurality of types of measurement objects, a determination criterion setting unit that accepts input of numerical values indicating an appropriate distance from the support surface to the light reflection position, and stores each numerical value in the memory as a determination reference value;
Selecting means for selecting one of the plurality of determination reference values;
Comparing means for comparing the data after the conversion processing with the selected criterion value for the measurement object;
A displacement sensor comprising output means for outputting a comparison result by the comparison means.

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