JPH07314295A - Tracer control method - Google Patents

Abstract

PURPOSE:To correct the fine error of a sensor due to the temperature variation, in the tracer control method for measuring the shape of the surface of a model which is fixed on a table, by a tracer head. CONSTITUTION:A noncontact type sensor 25 as sensor for shape displacement detects the shape displacement quantity of the surface of a model 26 on a table 21, and the detection value is sent to a digitizing controller 10 side. At the place different from the table 21, a noncontact type sensor 1 as a sensor for the constant displacement quantity is fixed. The noncontact type sensor 1 always detects the standard displacement quantity d0 as the constant displacement quantity, and sends this detection value to the digitizing controller 10 side. A detection value correcting means 10a corrects the detection value of a noncontact type sensor 25 on the basis of the detection value of the noncontact type sensor 1. A shaft control means 10b controls a motor 22, etc., on the basis of the detection value of the noncontact type sensor 25 which is applied with correction, and controls the shift of the table 21 and the shift of the noncontact type sensor 25. Accordingly, the noncontact type sensor 25 copies the shape of the surface of the model 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracing control system for measuring the shape of a model surface fixed on a table by a tracer head, and more particularly to a tracing control system for correcting a measurement error of the tracer head.

[0002]

2. Description of the Related Art Generally, in a method of measuring the shape of a model surface fixed to a table, axis control is performed so that the position of a tracer head to which a stylus or an optical sensor is attached is always at a constant distance from the model surface, The digitizing data was obtained by periodically detecting the axis position.

However, since the measured value of the tracer head slightly changes due to temperature change, high-precision measurement cannot be performed as it is. Therefore, conventionally, a correction table according to the temperature is provided, and the detection value of the tracer head is corrected by the correction data according to the room temperature during the work.

[0004]

However, since the room temperature slightly changes during the work, the detected value of the tracer head also changes accordingly. In the past, there was no technology to correct this slight change in the detected value.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a profile control system capable of compensating a slight variation in a detected value of a tracer head.

[0006]

According to the present invention, in order to solve the above problems, in a tracing control system in which the shape of a model surface fixed to a table is measured by a tracer head, the model is fixed to a place different from the table. A constant displacement amount sensor for constantly measuring a constant displacement amount, a shape displacement sensor provided on the tracer head for measuring the shape displacement of the model surface, and the shape based on a detection value of the constant displacement amount sensor. Detection value correction means for correcting the detection value of the displacement sensor, and axis control means for controlling the movement of the tracer head so as to follow the model surface shape based on the corrected detection value of the shape displacement sensor. There is provided a contour control method characterized by having:

[0007]

The constant displacement amount sensor fixed at a place different from the table constantly measures the constant displacement amount. On the other hand, the shape displacement sensor provided in the tracer head measures the shape displacement of the model surface. The detection value correction means corrects the detection value of the shape displacement sensor based on the detection value of the constant displacement amount sensor. The axis control means controls the movement of the tracer head so as to follow the model surface shape based on the corrected detection value of the shape displacement sensor.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the concept of the function of this embodiment.
The non-contact type sensor 25 as a shape displacement sensor is attached to a shaft (not shown), detects a displacement amount of the shape of the model 26 surface on the table 21, and sends the detected value to the digitizing control device 10 side. . A non-contact type sensor 1 as a constant displacement amount sensor is fixed at a place different from the table 21. Here, the non-contact type sensor 25 and the non-contact type sensor 1 are sensors manufactured according to exactly the same standard. The non-contact sensor 1 constantly detects the reference displacement amount d _0, which is a constant displacement amount, and sends the detected value to the digitizing control device 10 side. The detection value correction means 10a corrects the detection value of the non-contact sensor 25 based on the detection value of the non-contact sensor 1. The axis control unit 10b controls the motor 22 and the like based on the corrected detection value of the non-contact sensor 25 to control the movement of the table 21 and the movement of the non-contact sensor 25. As a result, the non-contact type sensor 25 follows the shape of the model 26 surface.

FIG. 2 is a block diagram showing the configuration of a tracing / digitizing system according to an embodiment of the present invention. The tracing / digitizing system mainly includes a digitizing control device 10 and a tracing machine 20. The processor 11 of the digitizing control device 10 uses the bus 1
The system program stored in the ROM 12 is read via 9 and the overall operation of the digitizing control device 10 is controlled according to this system program. RAM13
In, temporary data is stored. Non-volatile memory 1
Reference numeral 4 is backed up by a battery (not shown), and various parameters such as a profile mode, a profile plane, and a profile speed input by a key on a panel (not shown) of the CRT / MDI unit 31 are stored.
The non-volatile memory 14 also stores digitizing data of the model surface shape measured by the tracer head 24 of the tracing machine 20.

A non-contact type sensor 25 is provided at the tip of a tracer head 24 provided in the tracing machine tool 20. The non-contact sensor 25 has two heads 25.
a and 25b. Each head 25a and 2
5b irradiates the surface of the model 26 with laser light, and detects the distance between the head and the surface of the model based on the reflection time.
This detected value is read by the control circuit 18 in response to a request from the processor 11 of the digitizing control device 10.

Further, the bus 19 is connected to the non-contact type sensor 1 shown in FIG. 1 through an interface (not shown). As described above, the non-contact type sensor 1 is fixed to a place different from the table 21, always detects the reference displacement amount d ₀ which is a constant displacement amount, and the detected value is processed by the processor 11 via the bus 19. Send to.

When the processor 11 receives the detection values from the non-contact type sensor 25 and the non-contact type sensor 1, the non-contact type sensor 25 based on the detection values of the non-contact type sensor 1.
Correct the detected value of. That is, since the detection value of the non-contact sensor 1 changes due to a change in room temperature or the like, the processor 11 obtains the difference Δd between the current detection value of the non-contact sensor 1 and the reference displacement amount d _0, and this difference The detection value of the non-contact sensor 25 is corrected by a correction amount according to the magnitude of Δd.

Thus, the processor 11 calculates the displacement amount of each axis based on the corrected detection value of the non-contact type sensor 25 and the signals from the current position registers 17x, 17y and 17z which will be described later, and is instructed. Based on the profile mode, the profile plane, and the profile speed, the X-axis speed command Vx and the Y-axis speed command V are generated by known techniques.
The y and Z axis velocity commands Vz are generated. These speed commands are input to the servo amplifiers 16x, 16y, and 16z, respectively, and the machine tools 2
Zero servo motors 22x, 22y and 22z are driven.

Further, the processor 11 controls the respective axes and, at the same time, controls the heads 25a and 25 of the non-contact type sensor 25.
The detected value of the displacement amount of b is read, and the normal vector of the model 26 surface is obtained using this. Then, the rotation command is output to the servo amplifier 16c so that the measurement axes of the heads 25a and 25b coincide with the vertical plane including the normal vector. The servo amplifier 16c drives the servomotor 22c based on this rotation command, and the heads 25a and 25a are driven.
Rotation control is performed while inclining the measurement axis of 5b about the Z axis by a predetermined angle.

By driving each servo motor as described above,
The tracer head 26 moves in the Z-axis direction, and the head 2
5a and 25b rotate around the Z-axis, and the table 21 moves in the X-axis and the Y-axis direction perpendicular to the paper surface,
Non-contact sensor 25 and model 26 of tracer head 24
It is controlled so that the relative positional relationship between them is kept constant.

Further, the servomotors 22x, 22y and 22z are provided with pulse coders 23x, 23y and 23z which generate detection pulses FPx, FPy and FPz, respectively, each time they rotate a predetermined amount. Current position register 17 in digitizing controller 10
x, 17y and 17z are detection pulses FPx, FPy
And FPz are respectively counted up / down according to the rotation direction to obtain current position data Xa, Ya and Za of the axis of the tracer head 24, and these position data are read by the processor 11. The processor 11 that has read the position data of each axis calculates the digitizing data of the model 26 based on these position data and the corrected detection value of the non-contact sensor 25, and stores it in the non-volatile memory 14.

The processor 11 sends an image display signal or the like showing the state of the tracing operation via the bus 19 to the CRT / MDI.
Send to unit 31. In the CRT / MDI unit 31, the built-in graphic control device converts the sent image display signal into image data and displays it on a display device (not shown). This display device displays an input operation screen for the condition of the conforming motion when starting the conforming motion. The operator uses keys on the panel (not shown) to input commands for the profile mode, profile plane, profile speed, and the like. The input commanded profile mode, profile plane, profile speed, etc. are read onto the bus 19 via the interface 32 and stored in the non-volatile memory 14.

An operation panel 30 is connected to the bus 19 via the interface 15. On the operation panel 30,
A profile operation start command, a stop command, etc. are issued. Each of these command signals is sent to the processor 11 via the interface 15 and the bus 19.

Next, the procedure of the detected value correction control of the tracing / digitizing system having the above-mentioned configuration will be described. FIG. 3 is a flowchart showing the procedure of the detection value correction control on the processor 11 side. [S1] The detection value of the amount of shape displacement of the non-contact sensor 25 is read. [S2] The detection value of the reference displacement amount d ₀ of the non-contact sensor 1 is read. [S3] A correction amount is calculated according to the difference Δd between the reference displacement amount d ₀ and the actual detected value. This correction amount is calculated, for example, by multiplying the difference Δd by a constant coefficient. [S4] The detection value of the amount of shape displacement of the non-contact sensor 25 is corrected by the calculated correction amount. [S5] Digitizing data is generated based on the corrected shape displacement amount and the current position data of each axis, and stored in the non-volatile memory 14.

As described above, in this embodiment, the table 21
The reference displacement amount d ₀ is constantly detected by the non-contact type sensor 1 fixed at a place different from the above, and the correction amount is calculated according to the difference Δd between the reference displacement amount d ₀ and the actual detected value. Since the detected value of the shape displacement amount of the non-contact type sensor 25 of the same standard as the non-contact type sensor 1 is corrected by the correction amount, it is possible to constantly correct the error of the detected value due to the change of the room temperature, More accurate digitizing data can be secured.

In this embodiment, the shape displacement sensor and
Then, the non-contact sensor 25 is used as a sensor for a constant displacement amount.
The non-contact type sensor 1 was used, but these are manufactured to the same standard.
Similar effects can be obtained even if the stylus is replaced. This
, The reference displacement is ε ₀Is used.

[0022]

As described above, according to the present invention, the constant displacement amount sensor, which is fixed at a place different from the table, constantly measures the constant displacement amount, while the shape displacement sensor provided on the tracer head is used. The shape displacement of the model surface is measured with, and the detection value of the shape displacement sensor is corrected based on the detection value of the constant displacement amount sensor, and the model surface shape is calculated based on the corrected detection value of the shape displacement sensor. Since the movement of the tracer head is controlled so as to follow, it is possible to constantly correct the error in the detection value of the shape displacement sensor due to changes in room temperature and the like, and it is possible to secure more accurate digitizing data. .

[Brief description of drawings]

FIG. 1 is a diagram showing a concept of functions of the present embodiment.

FIG. 2 is a block diagram showing a configuration of a tracing / digitizing system according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a procedure of detection value correction control on the processor side.

[Explanation of symbols]

 1 Non-contact type sensor (sensor for constant displacement amount) 10 Digitizing control device 10a Detection value correction means 10b Axis control means 11 Processor 12 ROM 13 RAM 14 Non-volatile memory 21 Table 24 Tracer head 25 Non-contact type sensor (for shape displacement) Sensor) 25a, 25b Head 26 model

Claims (4)

[Claims] 1. A constant displacement sensor for measuring the shape of a model surface fixed to a table by a tracer head, which is fixed at a place different from the table and constantly measures a constant displacement, A shape displacement sensor provided in the tracer head for measuring the shape displacement of the model surface, and a detection value correction means for correcting the detection value of the shape displacement sensor based on the detection value of the constant displacement amount sensor, An axis control means for controlling the movement of the tracer head so as to follow the model surface shape based on the corrected detection value of the shape displacement sensor, and a profile control method. 2. The profile control method according to claim 1, wherein the constant displacement amount is a reference displacement amount of the shape displacement sensor during profile execution. 3. The profile control method according to claim 1, wherein the constant displacement amount sensor and the shape displacement sensor are non-contact type sensors. 4. The profile control method according to claim 1, wherein the constant displacement amount sensor and the shape displacement sensor are styluses.