JPH02236703A - Numerical controller - Google Patents

Abstract

PURPOSE:To simplify the constitution of hardware and to detect a coordinate value with high accuracy even in fast travel by operating the position of a control axis at a time when an external signal is inputted from present position data read out periodically and data read out by an interruption processing. CONSTITUTION:The present position data of a moving touch sensor 8 is stored in a RAM 3 at every ITP cycle signal of an interval timer 11. A register 12 holds data of low-order bit in the interval timer counter 11 simultaneously with the input of a skip signal. Meanwhile, a microprocessor 1 executes the interruption processing to read out high-order bit data in the interval timer counter 11 and low-order bit data in the register 12 by the skip signal after inputting the external signal. The position of the control axis at the time when the external signal is inputted is operated from the present position data read out periodically and the data read out by the interruption processing. Thereby, the constitution of the hardware can be simplified, and the coordinate value can be detected with high accuracy even in the fast travel.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a numerical control device for controlling machine tools and the like, and particularly to a numerical control device having a skip function for controlling position measurement, positioning, etc.

[Conventional technology]

Among numerical control devices, one-axis control numerical control devices are used in general industrial machines that perform processing, measurement, and the like. In such industrial machines, a skip function is required on the numerical control device side in order to perform control such as axis position measurement or positioning in response to external signal input.

The skip function will be explained below. FIG. 3 is a diagram showing the concept of the skip function. The numerical controller is at point Al-
It receives a movement command to pass through A2-A3 and executes it in the order of a first block from point AI to A2 and a second block from A2 to A3. When an external signal (skip signal) SK is input from the outside at the position of point A4 during execution of the first block of this movement command, the numerical control device stops execution of the rest of this movement command and starts the next second block. Execute. That is, from the point A4 where the external signal SK is input, the second
Move to point A5 after block execution. In this way, when an external signal is input from the outside during a movement command, canceling the rest of the movement command being executed and executing the next block is called a skip function.

With this skip function, the coordinate value (current position) at the time when the external signal is input (point A4 in Figure 3) is stored in the numerical control device, so it can be used for position measurement or positioning when the amount of movement is unclear. It can be used for etc. For example, it can be used to measure a tool by placing the tool against a touch sensor or the like.

Conventionally, in order to realize this skip function inside a numerical control device, an external signal (skip signal) is captured as an interrupt signal of the microprocessor (CPU), and executed by software interrupt processing, and the skip function is executed at the time when the external signal is input. Coordinate values (current position) are recognized.

In addition, in order to realize this skip function, the ITP (
Interpolation) A cyclic counter is provided that is synchronized with the periodic signal and counts the number of system clocks within the period. Then, the counter is stopped at the same time as the external signal (skip signal) is input, and the value of the current position register read every ITP (interpolation) cycle and the value of the counter are processed to calculate the time when the external signal is input. The coordinate values (current position) are recognized.

(Problem to be Solved by the Invention) However, in the case of software interrupt processing as described above, after inputting an external signal, the microprocessor (CPU)
After analyzing the interrupt and recognizing that the external signal is a skip signal, the coordinate value (current position) is calculated. Therefore, since it takes time to calculate the coordinate values (current position) after the skip signal is input, the problem is that the faster the moving speed when the skip signal is input, the less accurate coordinate values can be recognized. There is.

Furthermore, if a cyclic counter is provided, for example, if the system clock is 1 μsec, the ITP (interpolation) period is 8
In the case of msec, an 8000-count cyclic counter must be prepared exclusively for the skip function, which poses a problem in that it imposes a heavy burden on the hardware.

The present invention has been made in view of the above points, and an object of the present invention is to provide a numerical control device having a skip function that has simplified hardware and can detect coordinate values with high precision even when moving at high speed. With the goal.

After inputting the external signal, interrupt processing is performed to synchronously read current position data of the control axis periodically, and read out upper bit data other than the lower bit of the interval timer counter and lower bit data in the storage circuit. and a microprocessor that calculates the position of the control axis at the time when the external signal is input from the current position data read periodically and the first and second data read by the interrupt processing. A numerical control device is provided.

[Means to solve the problem]

In order to solve the above problems, the present invention uses an interval timer counter that outputs a timing signal at regular intervals by counting the system clock in a numerical control device that detects the position of a control axis at the time when an external signal is input. a memory circuit that holds data of lower bits of the interval timer counter at the time when the external signal is input; , part of the output of this (lower bits)
A memory circuit is provided to hold the data at the time when an external signal is input. The upper bits of the interval timer counter are unlikely to change from the time an external signal is input until they are read by the CPU by an interrupt. Therefore, the value of the interval timer counter is used as is by the CPU.
Since there is no error in measurement accuracy even if the CPU
The software allows you to know the time in minute units at the time the external signal was input.

However, in rare cases, there is a carry of the counter and its value changes, so the carry is stored as an intermediate carry flag. As a result, the CPU performs correction calculations and calculates accurate values. [Example] Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 is a schematic diagram of the hardware of a numerical control device for implementing the present invention. In the figure, a microprocessor (CPU) 1 controls the entire numerical control device according to a system program stored in a ROM 2. ROM
2 uses EFROM or EEFROM.

A DRAM or the like is used as the RAM 3, and various data or input/output signals are stored therein. The position control circuit 4 receives a position command from the microprocessor 1 and controls the servo motor 6.
A speed command signal for controlling the servo amplifier 5 is output to the servo amplifier 5. Servo amplifier 5 amplifies this speed command signal and drives servo motor 6.

Although not shown, the servo motor 6 is connected to a position detector that outputs a position feedback signal and a tachogenerator that outputs a speed feedback signal. A pulse coder or the like is used as the position detector, and feeds back position feedback pulses to the position control circuit 4. The tacho generator sends a voltage signal corresponding to the rotational speed of the servo motor 6 to the servo amplifier 5.
Give feedback.

The ball screw 7 is connected to the servo motor 6 and rotates in synchronization with the rotation of the servo motor 6.

The touch sensor 8 is moved by the rotation of the ball screw 7,
When it comes into contact with the object to be measured, it outputs a contact signal.

The skip signal generation circuit 10 receives the contact signal from the touch sensor 8 and generates a skip signal. This skip signal is output to the register 12 and is also output as an interrupt signal to the microprocessor 1 via the bus 9.

Current position data of the touch sensor 8 is stored in the RAM 3 from the position control circuit 4 via the bus 9. The timing of this storage is determined by the I output from the interval timer counter 1l.
This is done using a TP (interpolation) periodic signal.

The interval timer counter 11 inputs a system clock and outputs a predetermined timing signal by counting it. ITP periodic signal is usually 8ms e
c, and the system clock is 1 μsec. Therefore, the interval timer counter 11 outputs an ITP periodic signal every 8000 counts of the system clock.

The register 12 stores the lower bit (LSB) data of the interval timer counter 11 and holds the data by the skip signal from the skip signal generation circuit 10. The data in the register 12 is output to the bus 9 via the buffer 14. The most significant bit (MSB) of interval timer 11 is directly output to bus 9 via buffer 14 .

The register 12 is about 2 of the interval timer counter 1l.
It has a capacity that can store 0 μsec (16 to 32 counts).

The intermediate carry flag generation circuit 13 outputs the lower bit (LSB) and upper bit (LSB) of the interval timer counter 11.
A flag is generated to indicate a carry that occurred on the boundary with MSB). The generated flag is transferred to bus 9 via buffer 14.
Output to. The data in the buffer 14 is read out in response to a continuation command from the microprocessor 1.

Next, the operation of this embodiment will be explained. The servo motor 6 rotates in response to a movement command from the microprocessor 1 and moves the touch sensor 8. Current position data of the moving touch sensor 8 is stored in the RAM 3 every ITP periodic signal of the interval timer 11. When a contact signal is generated from the touch sensor 8 during the movement command, a skip signal is output from the skip signal generation circuit 10. The skip signal is taken into register 12 and microprocessor 1.

The register 12 holds the lower bit (LSB) data of the interval timer counter 11 at the same time as the skip signal is input. On the other hand, the microprocessor 1 executes interrupt processing for reading data from the buffer 14 in response to the skip signal.

At this time, after inputting the skip signal, the microprocessor 1
After analyzing the interrupt, the data in the buffer 14 is read out. Therefore, at the time when the read signal from the microprocessor 1 is input to the buffer 14, the value of the interval timer counter 11 has changed. That is, the interval timer counter 11 counts the system clock from the generation of the skip signal until the buffer 14 is read.

However, what changes during this time is the lower bit (LSB) of the interval timer counter 11, and the upper bit (
MSB) remains almost unchanged. Therefore, by reading the data in the buffer 14 at the time when the read signal is input from the microprocessor 1, it is possible to accurately read the value of the interval timer counter 11 when the skip signal is generated.

The register 12 is provided with a capacity that can sufficiently absorb the system clock generated between the generation of the skip signal and the readout of the buffer 14.
If the microprocessor 1 is executing other high-priority processing and it takes time to read the buffer 14, a carry will occur between the lower bit (LSB) and the upper bit (MSB), resulting in It becomes impossible to read the value. Therefore, in order to detect the occurrence of a carry, an intermediate carry flag generation circuit 1 is installed on the lower side of the upper bit (MSB).
3 is provided, and the presence or absence of a carry is set as a flag. Therefore, the microprocessor 1 reads the data in the buffer l4, and if the carry flag is set, subtracts the amount and performs correction processing.

Next, a case will be described in which the numerical control device of the above embodiment is used on a transfer line.

2. Description of the Related Art Transfer line NC devices incorporating an NC device on the line have come to be used as control devices for processing machines, assembly/inspection machines, etc. for mass production lines, such as those in the automobile industry. After machining is completed on this transfer line, a measuring station may be provided to measure the machining results.Hereinafter, an embodiment of the measuring station will be described.

FIG. 2 is a diagram showing the overall configuration of an embodiment in which the numerical control device of the present invention is used on a transfer line.

In this embodiment, a single-axis control NC device will be described.

The main control means 20 includes a communication protocol control means 22, an intersystem control means 28, a tape storage means 29, and a PC control means 2.
Consists of 1. The communication protocol control means 22 controls the protocol with an external LAN 23. The intersystem control means 28 includes a CRT/MD I2 4, a manual pulse generator 25, and an external interface (RS-
232C) performs control between each system of 26, and also performs serial boat management. The tape storage means 29 temporarily stores data from the intersystem control means 28. The PC control means 21 exchanges external signals via the DI/DO 27. Further, the PC control means 21 includes a uniaxial control NC device 43a of the processing station and a uniaxial control N of the measurement station.
A serial link control circuit (SLC) is installed in the C device 43b.
Communication lines L1, L2 and L3 via 32a and 32b
Connected with Serial link control circuit (SLC)
32a and 32b are provided in PC sections 31a and 3lb that execute sequence control of the single-axis control NC device. Is it a single axis system in the diagram? Although only two IIINC devices are shown, it goes without saying that more than this may be connected depending on the state of the transfer line 41.

The workpiece is moved in the direction of arrow 42 by transfer line 41. Then, predetermined machining is performed by the tool 40 controlled by the uniaxial control NC device 43a of the machining station. After finishing the machining at the machining station, the workpiece is moved to the next measuring station by the transfer line 41. At the measurement station, the machining state of the workpiece is measured by a single-axis NC device that controls the touch sensor 39.

Since the single-axis control NC device 43a and the single-axis control NC device 43b have the same configuration except for the difference in whether the object to be controlled is the tool 40 or the Cucci sensor 39, the single-axis control NC device 43a will be explained here.

The single-axis control NC device 43a includes an NC section 35a that executes an axis control function and a PC section 31a that executes a sequence control function.

The NC unit 35a includes the CPUI, ROM2, and RAM3 in FIG.
Consists of etc. The servo amplifier 36a receives an axis movement command from the NG section 35a and controls the rotation of the servo motor 37a. The tool 40 (touch sensor 39) is moved by a ball screw directly connected to the servo motor 37a. A workpiece that has moved on the transfer line 41 is processed into a desired shape by this tool 40. After finishing the processing, the workpiece moves on the transfer line 41 to the next measurement station.

Although the PC unit 31a is not shown, it is a CP that controls the entire
It consists of a ROM that stores a management program that controls the PMC and a ladder blog RAM that controls the machine, and a RAM that stores input/output signals and various data. The interface (Dr/Do) 33a exchanges input (DI) and output (DO) with the machine side. At the measurement station, a contact signal from the touch sensor 39 is taken into the uniaxial control NC device 43b via this interface 33b.

The PC control means 21 includes a host CPU, host SLC and R.
Has AM. Host CPU is host SLC and RAM
control. Input/output signals and various data are stored in the RAM.

SLC is the local S in the single-axis control NC device 43a.
It is connected to the LC 32a via a communication line (RS-422) L1. In addition, the local SLC3 of the processing station
2a and the local SLC 32b of the measurement station are similarly connected via a communication line (RS-422) L2. Optical communication may be performed using an optical cable for this communication line.

The local SLC 32a has an input memory and an output memory for data communication. Communication between each axis is performed by reading and writing information to and from this input memory and output memory. That is, when the single-axis control NC device 43b executes the skip function and finishes measuring the workpiece, the measurement result is written to the output memory in the local SLC 32b. Then, the host SLC of the PC control means 21 reads the data in the output memory via the communication line, and outputs the data to the local SLC 3 of the single-axis system 411 NC device 43a of the processing station.
2 Write to the input memory in a. Single axis system 4BNC
The device 43a reads the input memory, makes corrections according to the measurement results, and executes processing control for the next workpiece.

In this way, the measurement results from the measurement station can be fed back to the processing station via the communication line.

Since this SLC has a transfer capacity higher than that of IMBPS, the information exchange speed is extremely high. Furthermore, since priority control is performed by the main control means 20, it is possible to prevent the occurrence of a deadlock state in which other axes fall into a waiting state.

In this embodiment, a single-axis control NC device has been explained as an example of a numerical control device, but the effects of the present invention can also be achieved when applied to other FA devices, such as transfer line NC devices and robot control devices. it is obvious.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to realize a skip function that can simplify hardware and detect coordinate values with high accuracy even when moving at high speed.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the hardware configuration of a numerical control device for carrying out the present invention, and FIG. 2 is a diagram showing the overall configuration of an embodiment in which the numerical control device of the present invention is used on a transfer line. FIG. 3 is a diagram showing the concept of the skip function. 1 Processor 2 ---1--11 ----ROM 3 ------------------ R A M4
1-position control circuit o-----------------------------------------SKIPPING SIGNAL GENERATING CIRCUIT 1------ INTERVAL TIMER COUNTER 2--
−−−−−・−・− Register 3 ・Intermediate carry flag generation circuit 0−−1 to −
・---1--1 Main control means 1, L2, L3--
・1・−・Communication line 1 −−−−−−−−−−−−−−
− }Transfer Line Patent Applicant Fanuc Co., Ltd. Agent Patent Attorney Takeshi Hattori

Claims (5)

[Claims] (1) A numerical control device that detects the position of a control axis at the time when an external signal is input, which includes an interval timer counter that outputs a timing signal at regular intervals by counting a system clock; a storage circuit that holds the data of the lower bits of the interval timer counter at the time when the data of the lower bits of the interval timer counter is read out periodically in synchronization with the timing signal; An interrupt process for reading bit data and lower bit data in the storage circuit is executed after inputting the external signal, and the periodically read current position data and the first and second data read by the interrupt process are and a microprocessor that calculates the position of the control axis at the time when the external signal is input. (2) A means is provided for setting a flag indicating that a carry has occurred in the lower bits of the interval timer counter between the input of the external signal and the reading of the upper bit data and the lower bit data, and 2. The numerical control device according to claim 1, wherein the position of the control axis at the time when the external signal is input is calculated from bit data, lower bit data, and the flag. (3) The numerical control device according to claim 1, wherein the external signal is a skip signal, and the skip position of the control axis is detected. (4) A transfer line system having a first numerical control device for controlling workpiece processing at a processing station on the transfer line, and a second numerical control device for controlling workpiece measurement at a measuring station on the transfer line. In the numerical control device, the second numerical control device is constituted by the numerical control device according to claim 1, and the first and second numerical control devices are connected by a communication line so as to enable up and down communication. The measurement results of the second numerical control device are fed back to the first numerical control device via the communication line, and the first numerical control device performs axis control according to the fed-back measurement results. A numerical control device characterized by: (5) The numerical control device according to claim 4, wherein the first and second numerical control devices are commonly controlled by a main control means that is connected to enable vertical communication.