JP2677016B2 - Numerical control unit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a numerical control device that accurately positions a servomotor that is rotationally driven based on a command from a numerical control unit.

[Prior Art] FIG. 4 is a schematic configuration diagram of a servo mechanism in a conventional numerical controller, 1 is a CPU for controlling the entire numerical controller including the servo mechanism, and 2 is a CPU for controlling the servo mechanism. ,
Reference numeral 3 is an actuator for driving the servo motor 4, and 5 is an encoder attached to the servo motor 4, which detects a displacement caused by the rotation of the servo motor and outputs a pulse signal. Reference numeral 6 denotes an encoder interface (I / F) having a built-in counter circuit that counts the output pulses of the encoder 5.

Therefore, the movement command read into the main CPU1 is decomposed into movement commands for each servo axis per unit time,
The command value is passed to the servo CPU2, while the servo CPU2
Then, the command value is corrected as an output for actually moving the actuator 3, and is output to the actuator 3. The actuator 3 converts the command value into a voltage and current value to be applied to the servo motor 4, and the servo motor 4
Is driven to rotate. In this state, the encoder 5 detects the light transmitted through each slit of the disk 7 having two kinds of concentric slits by the two detectors 8 and
As shown in the figure, pulse signals whose phases are shifted from each other are obtained. The pulse signals are shaped by the filter circuit 9 and then transmitted by the driver IC 10 to the numerical controller via the transmission line 11. On the side of the numerical controller, this 2
Various kinds of pulse signals are received via the receiver 12 and input to the counter circuit 14 via the filter circuit 13, respectively. The counter circuit 14 detects the rotation direction of the servo motor 4 based on the phase difference between the two signals, and A count-up / count-down pulse is generated according to the phase difference, and count-up / down is performed depending on the rotation direction.

[Problems to be Solved by the Invention] As described above, since the conventional numerical control device directly transmits the output pulse of the encoder to the counting circuit provided on the side of the numerical control device, noise is added to the transmission line. In such a case, each pulse becomes an abnormal waveform and directly affects the count-up / count-down pulse, causing the contents of the counter circuit to be incorrect, and as a result, positioning by the servo motor cannot be performed accurately. It was

The present invention has been made in order to solve the above problems, and an object of the present invention is to obtain a numerical controller capable of eliminating the influence of the noise of the count-up / count-down pulse and accurately controlling the servomotor. To aim.

[Means for Solving the Problems] In the numerical control device according to the present invention, a servomotor that is rotationally driven based on a command from the numerical control unit, and a rotational displacement that is attached to the servomotor is detected to respond to the displacement. An encoder for generating a pulse signal, and a counter circuit provided in the encoder for counting the pulse signal, and the numerical control unit in response to a transmission request signal from the numerical control unit for the count value of the counter circuit. And latches the count value of the counter circuit in response to the transmission request signal from the numerical control unit, and latches the latched current value and the previous transmission request signal from the numerical control unit. If the difference between the current value and the previous value is larger than the specified value, the alarm signal An alarm generating circuit to be transmitted to the numerical value control unit is provided in the encoder.

Further, in the numerical control device according to the present invention, a servomotor that is rotationally driven based on a command from the numerical control unit, and a servomotor that is attached to the servomotor to detect its rotational displacement and generate a pulse signal corresponding to the displacement. An encoder and a counter circuit provided in the encoder for counting the pulse signal are provided, and the count value of the counter circuit is output to the numerical control unit in response to a transmission request signal from the numerical control unit, and the numerical value is also output. The encoder is provided with an alarm generation circuit for transmitting an alarm signal to the numerical control unit when the transmission request signal is not transmitted from the control unit to the encoder even after a predetermined time elapses.

Further, in the numerical control device according to the present invention, a servomotor which is rotationally driven based on a command from the numerical control unit, and an encoder which is attached to the servomotor and which detects a rotational displacement of the servomotor and generates a pulse signal corresponding to the displacement. A counter circuit provided in the encoder for counting the pulse signal, and a counter circuit for serially transmitting the count value of the counter circuit to the numerical control unit in response to a transmission request signal from the numerical control unit. Provided serial transmission means, the encoder, the direct transmission means for directly transmitting the pulse signal generated by the encoder to the numerical control unit, and provided in the encoder, by the signal from the numerical control unit, The pulse signal generated by the encoder is directly transmitted to the numerical control unit by the direct transmission means. The case of transmission, in which a signal converted to a serial signal by the serial transmission means and means for switching between a case of transmitting to the numerical control unit.

[Operation] In the numerical control device according to the present invention, the count value of the encoder is checked every time, and if the count value shows discontinuity, the numerical control unit is notified that a defect has occurred in the count value. .

Further, when the transmission request signal is not transmitted from the numerical control unit to the encoder within a predetermined time, the numerical control unit is notified by an alarm signal.

Furthermore, depending on the signal processing form in the numerical control unit, it is possible to select whether to directly transmit the pulse signal or convert it into a serial signal for transmission.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is a schematic configuration diagram of a numerical controller to which the present invention is applied. In FIG. 1, 1 is a main CPU that controls the entire numerical control device, and 2 is a CP that controls the servo mechanism.
U, 3 are actuators that actually drive and control the servo motor, 4 is a servo motor, and 5 is an encoder mounted on the anti-load side of the servo motor 4, and outputs two position detection signal pulses of A phase and B phase. . These configurations are the same as the conventional one. Reference numeral 20 is an encoder interface (I / F) including a counting circuit for counting each of the A-phase and B-phase signals output from the encoder 5, and 21 is a serial I / F for transmitting serial transmission data of the counter value. These are O interfaces, which are built in the encoder 5 part in advance. FIG. 2 is a hardware configuration diagram of the encoder 5 according to the present invention, which is configured by a custom IC. That is, the encoder has a disk 7 having two kinds of concentric slits, a detector 8 that detects light passing through the slits and outputs two pulse signals having different phases, and further waveforms of these two signal pulses. The filter circuit 9 for shaping is the same as the conventional one. 22 is a counter circuit (CNT1) that counts up / down depending on the phase difference between the A-phase signal pulse and the B-phase signal pulse output from the filter circuit 9, and 23 is a counter circuit that receives an overflow / underflow pulse of the counter circuit 22 Upper counter circuit (CNT
2) and 21 are serial I / Os for latching the count data of the counter circuits 22 and 23 and transmitting them to the numerical controller.
Interface (I / F), 25 is a timing control unit that supplies a count data latch and transmission clock, each counter clock pulse in response to a count data transmission request (RTS) from the numerical control device side, and 26 is previously latched The alarm generation circuit compares the difference between the count data and the count data latched this time with a certain fixed value and generates an alarm when the difference is too large.

Next, the operation will be described. Generally, in the numerical control device, when detecting the position of the servo motor, the count data is sampled at a certain timing, and at other timings, the counters 22 and 23 are set to the servo motor 4 respectively.
The up / down count is executed depending on the rotation direction of. Therefore, in the present invention, when a transmission request (RTS) is sent from the numerical control device side to the encoder 5 at the sampling timing, the timing control unit 25 on the encoder side receives the signal and count data of the counters 22 and 23 is counted. Is latched, and the count data at this time is transmitted from the serial I / O interface 21 to the numerical control device side through the signal line of Ch.A. In this case, the previous RT
The alarm generation circuit 6 compares the count data latched by the S signal with the count data latched this time, and if the difference is too large, the alarm generation circuit will
Sends an alarm signal to the numerical controller via Ch.B.

FIG. 3 shows a specific example of the timing of transmitting the count data. (A) shows that the count signal is transmitted to the numerical control device synchronously in synchronization with the sampling timing of the request signal (RTS). Shows the normal operation, and (b) shows the state where the alarm signal is sent to the transmission path of Ch.B because the request signal (RTS) is missed once. This alarm signal is the next request signal (RT
It is reset by S).

In the above operation, the alarm signal is generated by comparing the count data before and after the count data.
If the servo motor is rotating at a low speed, the difference between the count values does not reach the upper limit, so the request signal (RT
It is better to use the timer from S) to generate an alarm.

Further, in FIG. 2, when the SEL signal is switched from the numerical control device side, it becomes equivalent to the conventional encoder.

Further, by customizing the electric circuit of FIG. 2 into a custom IC, it can be mounted on the internal printed circuit board mounted on the encoder as it is, and the entire structure can be made compact.

In the above embodiment, the configuration is switched between the case where the output pulse of the encoder is directly transmitted and the case where the count data accumulated in the counter circuit of the output pulse is transmitted serially, but it is also possible to transmit both of them at the same time. Well, especially in this case, by providing a counter I / F that counts the pulses transmitted on the numerical controller side, it becomes possible to compare the count data on both the encoder side and the numerical controller side, improving reliability. Can be achieved.

[Effects of the Invention] Since the present invention is configured as described above, it has the following effects.

That is, a servomotor that is rotationally driven based on a command from a numerical control unit, an encoder that is attached to the servomotor and that detects a rotational displacement of the servomotor to generate a pulse signal corresponding to the displacement, and the pulse signal provided in the encoder. And a counter circuit that counts the output value to the numerical control unit in response to a transmission request signal from the numerical control device, and responds to a transmission request signal from the numerical control unit. Latch the count value of the counter circuit, and compare this latched current value with the previous value of the count value of the counter circuit latched by the previous transmission request signal from the numerical control unit,
Since the encoder is provided with an alarm generation circuit that transmits an alarm signal to the numerical control unit when the difference between the current value and the previous value is larger than a predetermined value, the numerical control in which the control cycle, that is, the generation interval of the request signal is different. Not only can send and receive signals to and from the encoder freely, but also can constantly detect encoder abnormalities, thus providing a highly reliable and flexible numerical control device. You can

In addition, the signal that serves as a trigger for latching the count value of the counter circuit for comparing the current value with the previous value and the signal that serves as a trigger for outputting the count value of the count circuit to the numerical control unit are used. It has a unique effect that it is not necessary to newly generate a signal that becomes a trigger for latching a value.

Further, a servomotor that is rotationally driven based on a command from the numerical control unit, an encoder that is attached to the servomotor and that detects a rotational displacement of the servomotor to generate a pulse signal according to the displacement, and the pulse signal provided in the encoder. And a counter circuit that counts the value of the counter circuit in response to a transmission request signal from the numerical control unit to the numerical control unit, and the numerical control unit sends a predetermined transmission request signal to the encoder. If the encoder is provided with an alarm generation circuit that transmits an alarm signal to the numerical control unit when it is not transmitted even after a lapse of time, even if the numerical control unit has a different control cycle, that is, a request signal generation interval, Not only is it possible to freely send and receive signals between Can detect that) a transmission request signal from the control unit after a predetermined time has elapsed is not sent, it exhibits a unique effect that it is possible to obtain a numerical controller and hence a high flexibility and reliability.

Furthermore, a servomotor that is rotationally driven based on a command from the numerical control unit, an encoder that is attached to the servomotor and that detects a rotational displacement of the servomotor to generate a pulse signal according to the displacement, and the pulse provided on the encoder. A counter circuit for counting signals, serial transmission means provided in the encoder for serially transmitting a count value of the counter circuit to the numerical control unit in response to a transmission request signal from the numerical control unit, and the encoder And a direct transmission means for directly transmitting the pulse signal generated by the encoder to the numerical control section, and a signal provided from the numerical control section provided in the encoder,
Means for switching between the case where the pulse signal generated by the encoder is directly transmitted to the numerical control section by the direct transmission means and a case where a signal converted into a serial signal by the serial transmission means is transmitted to the numerical control section; Since it is equipped with, it is possible not only to send and receive signals freely with the encoder even if the numerical control unit has a different control cycle, that is, the generation interval of the request signal, and also to connect the encoder and the numerical control unit. It is possible to switch between transmitting the pulse signal generated by the encoder directly to the numerical control unit and transmitting the signal converted into a serial signal to the numerical control unit without any change work, which results in high reliability and flexibility. A unique effect of being able to obtain a certain numerical control device is exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a numerical controller according to an embodiment of the present invention, FIG. 2 is a circuit configuration diagram of an encoder thereof, FIG. 3 is a diagram showing a count data transmission operation, and FIG. 4 is a conventional numerical value. FIG. 5 is a schematic configuration diagram of the control device, FIG. 5 is a circuit configuration diagram of the encoder, and FIG. 6 is a signal waveform diagram thereof. 1 is a main CPU, 2 is a servo CPU, 4 is a servo motor,
5 is an encoder, 20 is an encoder I / F, 21 is a serial I / F
/ OI / F, 22 counter circuit, 23 upper body counter circuit, 25
Is a timing control unit, 26 is an alarm generation circuit, and the same reference numerals in the drawings denote the same or corresponding portions.

Claims (3)

(57) [Claims] 1. A servomotor which is rotationally driven based on a command from a numerical control section, an encoder which is attached to the servomotor and which detects a rotational displacement of the servomotor to generate a pulse signal according to the displacement, and which are provided in the encoder. A counter circuit that counts the pulse signal, and outputs a count value of the counter circuit to the numerical control unit in response to a transmission request signal from the numerical control unit, and a transmission request signal from the numerical control unit. In response to, the count value of the counter circuit is latched, and this latched current value and the previous value of the count value of the counter circuit latched by the previous transmission request signal from the numerical control unit are compared, An alarm generation circuit for transmitting an alarm signal to the numerical control unit when the difference between the present value and the previous value is larger than a predetermined value is Numerical control device, characterized in that provided in the. 2. A servomotor which is rotationally driven based on a command from a numerical control section, an encoder which is attached to the servomotor and which detects a rotational displacement of the servomotor to generate a pulse signal corresponding to the displacement, and which are provided in the encoder. A counter circuit that counts the pulse signal, outputs the count value of the counter circuit to the numerical control unit in response to a transmission request signal from the numerical control unit, and requests the encoder to transmit from the numerical control unit. A numerical controller, wherein the encoder is provided with an alarm generation circuit for transmitting an alarm signal to the numerical controller when the signal is not transmitted even after a predetermined time has elapsed. 3. A servomotor which is rotationally driven based on a command from a numerical control section, an encoder which is attached to the servomotor and which detects a rotational displacement of the servomotor to generate a pulse signal corresponding to the displacement, and which are provided in the encoder. A counter circuit that counts the pulse signal, and serially transmits a count value of the counter circuit to the numerical control unit in response to a transmission request signal from the numerical control unit. Serial transmission means provided in the encoder, direct transmission means provided in the encoder for directly transmitting the pulse signal generated by the encoder to the numerical control section, and provided in the encoder, from the numerical control section In the case of directly transmitting the pulse signal generated by the encoder by the direct transmission means to the numerical control unit by the signal of, and in the case of transmitting the signal converted into the serial signal by the serial transmission unit to the numerical control unit. And a means for switching between the two.