JPH03167410A - Non-contact type digitizer and its calibrating and measuring method - Google Patents

Abstract

PURPOSE:To improve scanning efficiency by combining two sets of sensors so that two sensors are inclined in the forward and backward sides of the moving direction as one set in correspondence with the movements in the two-dimensional directions, and selecting one normal sensor when the light from one sensor hits a wall during scanning. CONSTITUTION:A model table 3 to which a model 2 is attached is movably mounted on a bed 1 and controlled by NC along the X axis. A main shaft head 6 is movably mounted on a cross girder 5 which is attached on columns 4 on both sides of the bed 1 and controlled along the U axis. Two pieces of optical sensors 10 (10A - 10D) are inclined at an angle theta and attached to the forward and backward parts in the directions of the X and Y axes, respectively. The output signals from the sensors 10 are sent into a digitization controlling device 11. Then, the output signals of the sensors 10 are selected in the device 11. When there is step part on the surface in the advancing direction and the emitted light from one sensor is screened, it is switched to the other sensor through a selecting and switching circuit 12. An analog voltage corresponding to the amount of displacement is outputted by operation based on the output signal from the sensor selected with the circuit 12.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a digitizer equipped with a plurality of sensors in a sensor head for digitizing a model shape and creating an NC program. Conventional Technology Optical sensors that irradiate a target with a beam of light from a semiconductor laser or an infrared LED, and then focus the reflected light onto a position detection element using a light receiving lens to output a signal, are designed so that the sensor is optimized for measurement. It must be installed at an angle. This creates a shadow area, and a single sensor always has a dead zone, which limits the slope angle that can be measured. Conventionally, to solve this problem, the sensor head was controlled on two axes to rotate to change the inclination angle of the sensor and rotate to make this turning plane parallel to the direction of travel.
The entire model shape was measured by scanning in the X, Y) directions. This method of controlling the sensor head in two axes*Im has drawbacks such as complicated control, time-consuming switching, and the need for switching processing software. For this reason, Japanese Patent Application Laid-Open No. 61-1999 has developed a device that can perform scanning in two-dimensional directions with the same attitude without controlling the attitude of the sensor head.
There is a sensor for a laser processing machine as shown in Japanese Patent No. 108484. This device has, at the tip of the processing nozzle, a plurality of light emitting means for irradiating a light beam and a plurality of detection elements for imaging the light beam 7, and output signals from the plurality of detection elements are calculated by calculation. By averaging, the focus of the laser processing beam is positioned at a predetermined processing portion on the surface of the target workpiece.

yA Problem to be Solved by the Invention The technology of JP-A No. 108484/1984 described in the prior art section focuses light spots irradiated onto the surface of a target workpiece by a plurality of light projecting means onto a plurality of corresponding detection elements. Since multiple detection outputs obtained by imaging are averaged and position control is performed, for example, as in the case of the laser processing machine in this example, the focus of the processing beam is slightly shifted from the target workpiece surface. This method can only be used if there are no major hindrances, and if there is a vertical wall or near-vertical slope on the measurement surface, the irradiated light will be blocked by the sensor, and the average value will be greatly disturbed. The problem is that it cannot be used. Furthermore, when using multiple sensors, the relationship between the measured displacement and the sensor output value will differ depending on the sensor due to differences in optical magnification of each sensor and installation errors when attached to the laser head, resulting in measurement accuracy. There is a problem that it decreases.

The present invention has been made in view of these problems of the conventional technology, and its objects are to provide a non-contact digitizer capable of scanning in two-dimensional directions with the sensor head in the same posture, and Alternatively, the present invention aims to provide a calibration method and a measurement method that can easily and accurately calibrate measured displacement when checking for abnormalities. Means for Solving the Problems In order to achieve the above object, the non-contact digitizer and its calibration method and measurement method in the present invention include a set of at least two digitizers tilted at the same angle in the front and back of the moving direction. At least two sets of non-contact sensors are combined to correspond to movement in two-dimensional directions, and a sensor hand that detects one point on the measurement surface and one set of sensor output corresponding to the direction of movement are selected, and a sensor hand that detects one point on the measurement surface is selected, and a sensor head that detects one point on the measurement surface is selected, and a sensor output is selected that corresponds to the direction of movement. A selection switching circuit that switches only to the output of the other sensor while there is a wall that returns the luminous flux of one sensor, and scanning data based on the set of sensors selected by the selection switching circuit and the output of the other sensor that has been switched. and a digitizing control device that creates NG shape data.

Also, each of the plurality of sensors measures a calibration gauge whose exact step size on the model table is known,
Calibration coefficients are calculated and stored for each sensor, and the measured displacement amount of the corresponding sensor is calibrated. In addition, each of the plurality of sensors measures a calibration gauge whose exact step size on the model table is known, calculates and memorizes a calibration coefficient for each sensor, and calibrates the output value of the corresponding sensor. It is measured by converting it into the amount of displacement. A set of two sensors tilted forward and backward in the working direction of movement are combined 2 & II (4 in total) in two orthogonal directions, and one of these four sensor output signals corresponding to the direction of movement is While scanning is performed by selecting the sensor outputs of &ll (2), if one sensor is in the shadow due to hitting a wall, the other sensor output which is normal is selected and scanning is performed. In addition, the calibration coefficient for each sensor output is determined using a calibration gauge placed on the model table, and the sensor output or displacement amount is calibrated. Embodiment 1 About the first embodiment Fig. 1. This will be explained with reference to FIG.

In the well-known digitizer, the model table 3 on which the model 2 is attached is movable on the guide surface in the X-axis direction cut into the bed 1. The X-axis is controlled by the NC. Square columns 4 are erected on both sides of the bed 1, and the columns 4
The main shaft is on the guide surface in the Y-axis direction of the crossbeam 5 installed above!
Ilt6 is movably mounted, . YM control is performed by NC. A tracer head quill 7 is attached to the spindle head 6.
It is movable in the axial direction and is NC controlled. Quill 7
As shown in Fig. 2, the tracer head 9 attached to the tip has a total of four pieces tilted back and forth in the X-axis and Y-axis directions at an angle θ that is optimal for light reception, and detects a single point on the model 2. Two optical sensors IOA to 10D are installed in the X-axis direction and two in the Y-axis direction. Sensor IOA~10
D can be, for example, an optical distance sensor, etc., which irradiates the object with the light flux of a pulse-lit infrared LED through a light-receiving lens, and directs the reflected light onto a position detection element using the light-receiving lens. It focuses light and outputs a signal corresponding to distance information to the target object.Sensor 1
The output fs number from 0A to 100 is output from the digitizing control device l1.
Sent to. When the scanning direction is the X-axis direction, the control device 11 outputs the output signal of the sensor IOA10B,
In the case of the axial direction, the output signals of sensors IOc and 10D are selected, and when the irradiation light of one sensor is blocked by a step in the front in the direction of movement during scanning, the output signal of the other sensor that is operating normally is selected. It has a built-in selection switching circuit 12 that switches to. And this selection switching circuit l
Based on the sensor output signal selected by 2, the anag r:I1t pressure corresponding to the amount of displacement is output by calculation. The Z-axis is NC-controlled so that the output voltage from this control device fil is always a constant value (for example, zero volts), and NC shape data is created from the ever-changing scanning data of the moving axis and tracer head tile at this time. It is supposed to be done.

Next, the operation of the first embodiment will be explained with reference to the flowchart in FIG. In step S1, it is determined whether scanning is performed by moving the model table 3 in the IiIILz is checked as to whether the scanning is based on axis movement, and if yes, in step S4, the sensors 10C, 1
The output of 0D is selected and translated. Next, in step S5, X is always set during scanning.
It is confirmed whether there is a wall in the axial position, and if the irradiation light is not blocked, the answer is NO, and in the stethop s6, the sensor IOA
, 10B are input, and undergo coordinate transformation in step s7. Further, in step S5,
When the wall comes to the axis scanning position, the answer is YES, and in step S8, the sensor IOA or 10 on the front side in the traveling direction is
It is detected that the irradiated light B is blocked by the wall and an abnormality occurs in the output signal, and it is determined whether the abnormality is on the sensor IO8 side. If YES, the output is switched to only the sensor IOA in step S9; if NO, it is determined in step SIO whether the wall is on the sensor IOA side; if NO, the process returns to step s5; If so, in step 311, it is switched only to the output of sensor IOB. At the step S6, the output signal of either the sensor IOA or IOB thus switched is input, and at the step S7, the output signal of the sensor a!
It will be converted. Next, in step Sl2, it is determined whether l line scanning is completed or not! ! If the answer is NO, the process returns to step S5, and if the answer is yes, the process returns to step S1 to continue scanning the next line in the manner described above. On the other hand, in step S4, the selected sensor 10C,
In the case of scanning in the Y-axis direction using the 10D, whether there is a wall at the position in the Y-axis direction at all times during scanning in the SteSob 513 is li! If the irradiation light is not blocked,
If no, in step S14, the sensors 10C, 10
The output signal of D is input and undergoes coordinate transformation in step 315. In addition, if the wall comes to the Y-axis scanning position in step S13, the answer is YES, and the stencil S
In I6, it is determined whether there is an abnormality in the output of sensor 100 (@), and if yes, sensor lO is detected in step SIT.
It can be switched to only the output of C. If no, it is confirmed in step 318 whether the wall is on the sensor IOC side, and if no, the process returns to step 313, and if YES, the process is switched to only the output of the sensor IOD in step 519. In step S14, the output signal of either the sensor IOC or 100 thus switched is input, and the coordinates are transformed in step S15. Next, in step 520, it is confirmed whether the l line scanning is completed, and if no, the stenoprop 31
If the answer is YES, the process returns to step S1 to continue scanning the next line. Next, Fig. 1 shows the second embodiment. This will be explained with reference to Figure 2. The difference from the first embodiment is that a calibration gauge 13 is placed on the model table 3, and a description of the same parts will be omitted to avoid duplication. Calibration gauge 13
is a square block having an upper step surface 13a, a middle step surface I3b, and a lower step surface 13c on which steps a and a' of exactly the same size are formed.

Next, the procedure of a calibration method using a calibration gauge for a digitizer having a plurality of sensors according to the second embodiment will be explained with reference to the flowchart shown in FIG. In step 321, it is determined whether the sensor calibration is to be performed, and if yes, in step S22, the sensor hand 9 is positioned above the middle stage 13b of the calibration gauge 13 by moving along the X and Y axes. In step S23, the quill 7 is moved downward in the Z-axis direction, and the sensor IOA
~10D is positioned at a predetermined measurement distance above the middle surface 13b of the gauge 13, and in step 324,
Activate each sensor and output a signal. Step S2
5, it is confirmed whether the sensor output is within the measurement range, and if NO, the process returns to step 323; if YES, in step 326, the output values of the sensors IOA to 10D are set as the reference value NO. In step S27, the gauge 13 is moved so that the upper surface 13a is directly below the sensor, and the measurement surface is set to +a mm. In step 328, the output value of one sensor IOA is selected from among the four sensor outputs, and this output value is set as N+a. Stemp S2
9, the calibration coefficient Kpi (in this case sensor 10A
Calculate the coefficient K p + ) of a / (N+a − N
o). Here, a is the step size of the gauge.
In step S30, it is determined whether each sensor has finished &[,
In this case, the answer is no, and in step 328, the calibration coefficient Kpt is determined again. In this way, 4 sensors IO
When all the coefficients Kpi of A to IOD are determined, the answer is YES in Stenop S30.

Next, in step S31, the lower surface 1 of the gauge 13
The gauge 13 is moved so that the position 3c is directly below the sensors IOA to 10D to set the measurement surface to -a'llll, and in step S32, the output of one sensor 10A is selected and set as N -a'. ．． In step S33, the calibration coefficient Kmi (in this case, the coefficient Kmi of the sensor IOA)
) is calculated using the operation 1a'/(N-a-No). Here, 1a is the gauge step size. In step 334, it is confirmed whether each sensor is finished. In this case, the answer is NO, and the process returns to step s32. Based on the output -a' of sensor IOB, in step S33, the coefficient Km of sensor IOB is determined.
* is required. When all four coefficients Kmi are obtained in this way, the answer is YES in step S34, and the calibration coefficients Kpi, K are determined in step S35.
ni is memorized. Next, when the model 2 is placed on the model table 3 and normal model measurement is started, the SteSob 336-1 to S
36-4, for each sensor lOA to 10D output, in steps 337-1 to S37-4, for the output on the tenth side with respect to the reference value, n K p+ "' K
pa, and the output on one side has a coefficient Km+~Kma
Calibrate by multiplying each output by
-1-338-4, the calibrated output is converted into a displacement amount, and in step S39, digitizing processing is performed based on this displacement amount. Note that if the sensor output is non-linear, it can have many coefficients.

Next, as a third example, we will explain a method of checking when the non-contact digitizer starts working. The difference from the first embodiment is that the quill 7 is located at the upper end (retracted) position shown in FIG.
The difference L0 between the distance L in the Z-axis direction from the lower end surface of the installed sensors IOA to 10D to the top surface of the table 3 and the sensor-specific standoff amount (measured distance M) Lt is determined in the control device Itll. This has been memorized, and the operation will be explained below with direct reference to the flowchart in Figure 6. In step S41, the table 3, the spindle head 6. The quills 7 are moved in the X, Y, and Z axis directions and positioned at the retracted position, and in step 342, the quill 7 having the sensors IOA to 10D at its tips is moved downward in the Z axis direction, and at this time, the quill 7 is moved in the Z axis direction. The amount of movement L from the evacuation position is read and it is confirmed whether L = LO,
If no, the process returns to step S42 and the two-axis movement is continued. Then, when it becomes L "" Lo, the result is YES, and in step 344, the output of the sensor lOA is checked. If the output is not output normally, the result is NO, and in step S45, the alarm is stopped, and at the same time, an operator call is made by light or sound. will be held. If YES in step S44, then the output of the sensor IOB is checked in step S46, and if NO, an alarm is generated in step 345. In this way, the output of each sensor is checked one after another, and when the output of the last sensor IOD is checked and the result is YES in step S47, the check is completed, and normal model measurement operation begins in the step S47. This checking method can be easily performed not only when starting up in the morning, but also when necessary. If even one sensor has an abnormal output or does not output, the alarm will stop, so you can increase the scanning speed with peace of mind. Improved operating rate can be measured. Effects of the Invention Since the present invention is structured as described above, it produces the following effects. In the non-contact digitizer of claim 1, a set of two sensors tilted forward and backward in the direction of movement are combined 2&II in response to movement in two-dimensional directions, and a set of two sensors in the direction of movement are combined. In addition to selecting the sensor output for scanning, it also selects one normal sensor where the wall is located during scanning, making it possible to scan in two-dimensional directions with the sensor in the same orientation, which is different from conventional methods. As shown in the figure, the time required to change the sensor head position and switching processing software are no longer required, improving scanning efficiency. In the non-contact digitizing calibration method and measurement method of claim 2.3, each calibration coefficient is calculated and stored using a calibration gauge whose exact step size is known, and the measurement of the corresponding sensor is performed using this coefficient. Calibration of displacement,
Alternatively, since the sensor output is calibrated, highly accurate calibration can be performed in a short time even if there are a large number of sensors. In addition, regular accuracy checks will reduce accuracy changes.
It is possible to maintain high accuracy at all times.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the digitizer, control device, and model of this embodiment, Fig. 2 is a perspective view showing a sensor head having four sensors and a calibration gauge, and Fig. 3 is an explanation of the operation of the first embodiment. 4 is a flowchart for explaining the operation of the second embodiment, FIG. 5 is a flowchart for explaining the sensor movement distance of the third embodiment, and FIG. 6 is a flowchart for explaining the operation of the third embodiment. be. 3...Model table 9...Sensor head 10A~1
0D・.・Non-contact sensor l1...Digitization control device

Claims (3)

[Claims] (1) Non-contact type sensors (10A, 10B
or 10C, 10D) corresponding to movement in two-dimensional directions (X, Y) and detecting one point on the measurement surface by combining at least two sensor heads (9), and the sensor output of the one set corresponding to the movement direction. a selection switching circuit (12) that selects the sensor and switches only to the output of the other sensor while there is a wall blocking the light flux of one sensor on the measurement surface during measurement; and the set of sensors selected by the selection switching circuit and the switching circuit. a digitizing control device (11) that creates NC shape data from scanning data output from the other sensor, and is capable of scanning in two-dimensional directions with a sensor head in the same posture. Digitizer. (2) Multiple sensors (10A
~10D), each of the calibration gauges (13) whose exact step dimensions (a, a') on the model table (3) are known are measured by the plurality of sensors, and each Calibration coefficient (Kpi,
A method for calibrating a non-contact digitizer, comprising calculating and storing Kmi) and calibrating a measured displacement amount of a corresponding sensor. (3) Multiple sensors (10A
~10D), each of the calibration gauges (13) whose exact step dimensions (a, a') on the model table (3) are known are measured by the plurality of sensors, and each Calibration coefficient (Kpi,
A method for measuring a non-contact digitizer, characterized by calculating and storing Kmi), calibrating the output value of a corresponding sensor, converting it into an amount of displacement, and measuring the amount.