JPH03273402A - Method for synchronized operation - Google Patents

Abstract

PURPOSE:To cope also with the temporary speed fluctuation of a first axis by executing the sampling of the control loop of a second and succeeding axes thereafter at timing determined by the output of the position detector of the first axis and making the second and the succeeding axes synchronize with the first axis. CONSTITUTION:The memories of NC devices 12 to 14 store position commands where corresponding axes of a second and the succeeding axes shall move to corresponding to A, B and C phase signals of an encoder for main axis 5, that is, in a form corresponding to the position of the main axis while the main axis rotates once. The NC devices 12 to 14 start the synchronized operation of corresponding motors 2 to 4 respectively with synchronizing with the input timing of a C phase signal, read the purposing command corresponding to A and B phase signals at sampling timing determined by the A and B phase signals, sample position detecting signals outputted by the position detectors of the respective axes and generate a positional deviation. Thus, it can be coped also with a case that the speed of the main axis changes temporarily.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a synchronous operation system for NC machines, robots, etc. in which a plurality of axes perform synchronous operations.

[Conventional technology]

FIG. 3 is a block diagram of a conventional example of a servo system in which a target command is given as a serial pulse train and the second axis is operated in synchronization with the first axis. In this method of giving target commands in the form of a serial pulse train and performing synchronous operation, the present applicant also proposed
In the publication No. 200311, a method for processing encoder pulses of the first axis is proposed. FIG. 3 will be briefly explained. A, B, and C phase pulses from the encoder of the first axis are input to the pulse processing circuit 51, and a target command for moving the second axis is output in the form of a serial pulse train.

The target value and current value counters 52 and 56 accumulate the input serial pulses and calculate the target value and current value.

The subtracter 53 calculates the difference between the target value and the current value and outputs it to the D/A converter 54, thereby forming a position loop. A speed controller 55 controls the speed of the second axis motor 57. Encoder 58 detects the position of the second axis motor.

However, in a servo system that gives such a target command as a serial pulse train, even if the target command is a constant speed, the output pulses of the pulse processing circuit 51 are not uniform, and all position loops are constructed with logic circuits. Therefore, there were problems such as a large number of parts and difficulty in changing the control method. Therefore, in many current servo systems, position loop calculations are performed on the CPU at a constant sampling period, and the target command is given to the CPU as several bits of data indicating the number of pulses to be moved during one sampling period.

FIG. 4 is a block diagram of a conventional example of a servo system to which such a synchronous operation method using sampling control is applied.

Here, the memory 71 stores the number of pulses to be moved during one sampling period as several bits of data. The sampler 72.75 closes at the sampling period T. The target value counter 73 accumulates the received data and calculates the target value. The current value counter 81 accumulates the input serial pulses and calculates the current value. A subtracter 74 subtracts the output of the current value counter from the output of the target value counter 74. The interrupt timer 76 generates an interrupt signal at a preset constant sampling period. C phase processing circuit 77
receives the C-phase pulse of the first axis encoder and generates an interrupt signal for starting synchronization. D/A converter 79 D/A converts the output of the subtracter 74. The speed controller 80 is D/
The speed of the second axis motor 82 is controlled in response to the output of the A converter 79, and the encoder 83 detects the rotational position of the second axis motor. Here, samplers 72 and 75, target value counter 73, subtracter 74, and interrupt timer 76 are
It is configured inside the PU78.

The CPU 7B starts synchronous operation in response to an interrupt signal from the pulse processing circuit 77, and then the interrupt timer 7
6, the difference between the target value and the current value is determined and output to the D/A converter 79.

[Problem that the invention seeks to solve]

In the synchronous operation method shown in Fig. 4 above, the timing to synchronize with the first axis is only at the start of synchronous operation, and subsequent sampling of the position control loop is performed in synchronization with the CPU's own constant cycle interrupt signal. This creates a problem when the speed of the first axis changes. This situation is shown in FIG. FIG. 5(a) shows the case where the first shaft is rotating at a constant speed. An example of the target command value at each sampling of the second axis is shown, and FIG. 5(b) shows the target command value at each sampling of the second axis when the rotational speed of the first axis is 172. , Fig. 5(C) shows that the rotational speed of the first shaft is 1.
/2, the interpolated target command value at each sampling time of the second axis is shown.

Assume that the second axis is being operated in synchronization with the first axis, which is currently rotating at a constant speed, according to the target command shown in FIG. 5(a).

Here, if the rotation speed of the first axis is reduced to 1/2 and the given target value is used as is, the same target value will be set twice at each sampling time as shown in Figure 5 (b). Since the target value becomes step-like, it is necessary to interpolate the target value as shown in FIG. 5(C). However, this interpolation requires an accurate ratio between the speed of the first axis and the sampling period of the second axis, and also strictly controls the phase relationship between the position of the first axis and the sampling period of the second axis. Must. Furthermore, this method cannot cope with cases where the speed of the first axis changes temporarily.

(Means for Solving the Problems) The first synchronous operation method of the present invention provides first and second signals corresponding to the rotational position and rotational direction of the first shaft, and the rotational position origin of the first shaft. A corresponding third signal is generated, the timing for starting the synchronous operation of the second axis and subsequent axes is determined by at least the third signal, and the timing of the second and subsequent axes set corresponding to the rotational position of the first axis is determined. By giving the target command for each axis to each control loop, the rotation of the second axis is synchronized with the rotation of the first axis.
This is a synchronous operation method in which the operation of each axis after the second axis is sampled and controlled, and the control loop of each axis after the second axis is sampled at a timing determined by the first and second signals.

The second synchronous operation method of the present invention is the first synchronous operation method of the first synchronous operation method. Second. A third signal is generated by an encoder and these are used as A, B, and C phase signals, and the number of A-phase and B-phase signals output following the output of the C-phase signal is When the set values match, the synchronous operation of the relevant axis is started.

(Function) The first synchronous operation method of the present invention includes sampling of the control loop (sampling of target commands for each axis after the second axis, which are set corresponding to the position of the first axis, and Since the subsequent sampling of the position detection signal of each axis is performed at the timing corresponding to the position of the first axis, the target corresponding to the position is detected at the timing when the position of the first axis is detected, regardless of the speed of the first axis. Directives can be sampled.

Therefore, each axis from the second axis onward can be operated synchronously without causing a tracking error due to a change in the speed of the first axis.

As a result, once the target commands for each axis after the second axis are set, there is no need to change the sampling period or interpolate the target commands even if the speed of the first axis changes. Second. Accurate synchronous operation is achieved as long as the phase relationship between the third signals is constant.

In the second synchronous operation method of the present invention, after detecting the C-phase pulse corresponding to the position origin of the first axis, A.

After counting B-phase pulses by the set value determined for each axis after the second axis, synchronized operation of the corresponding axis is started.
The subsequent axes operate synchronously with each other or with their phases shifted by a predetermined phase angle with respect to the first axis.

(Embodiments) Hereinafter, specific embodiments of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a block diagram of a first embodiment of a multi-axis NC system to which the synchronous operation method of the present invention is applied.

In the multi-axis NC system of this embodiment, the second, third, and fourth axes operate in synchronization with the main axis (first axis). The main shaft motor 1 is controlled by a main shaft NC fill. The main shaft encoder 5 generates A and B phase signals (first and second signals) corresponding to the position and rotational direction of the main shaft, and a C phase signal (third signal) corresponding to the position origin of the main shaft. NC device 12
13 and 14 are each equipped with a memory (not shown), and the memory stores the position command to which the second and subsequent axes should move during one rotation of the main shaft, and the A of the main shaft encoder 5.
, B, and C phase signals, that is, in a form corresponding to the position of the main shaft. NC device 12.13.14 is C
Start the synchronous operation of the corresponding motors 2.3.4 in synchronization with the manual timing of the phase signal, and
A at the sampling timing determined by the phase signal
, - reads out the target command corresponding to the B-phase signal, and samples the position detection signal output by the position detector (not shown) of each axis to generate a position deviation. NC devices 12 to 14
Their functions and operations are similar. Each axis motor 2
, 3.4 are connected to the cutting tools 26, 27, 2 via the pole screws 22, 23, 24 under the control of the corresponding NC devices.
Move 8.

FIG. 2 is a block diagram of the NC device 12 of FIG. 1.

In FIG. 2, the pulse processing circuit 36 generates an interrupt signal for sampling control of the second axis using the A and B phase signals of the first axis encoder or a signal obtained by multiplying the A and B phase signals. The pulse processing circuit 37 receives and receives the C-phase pulse of the first axis encoder and generates an interrupt signal for starting synchronization. The memory 31 stores the number of pulses to be moved between interrupt signals output by the pulse processing circuit 36, that is, during one sampling, as several bits of data in a form corresponding to the position on the first axis. The samplers 32,35 are closed by an interrupt from the pulse processing circuit 36. The counter 33 accumulates the received data and calculates a target value. The counter 41 accumulates the input serial pulses and calculates the current value. Subtractor 34, D/A converter 39, speed controller 40, second axis motor 42 and encoder 43
The function and operation of are similar to the corresponding parts in FIG. Here, samplers 32, 35, target value counter 33,
The subtracter 34 is configured inside the CP03B.

The CPO 38 starts synchronous operation in response to an interrupt signal from the pulse processing circuit 37, and thereafter, in response to an interrupt for sampling control from the pulse processing circuit 36.
The difference between the target value and the current value is determined and output to the D/A converter 39. As a result, the sampling timing of the position control loop for each axis in section 2.3.4 is determined by the A and B phase signals.

Other operations are similar to conventional multi-axis NC systems.

Next, a second embodiment of the synchronous operation method of the present invention will be described.

In the multi-axis NC system on the wood flow side, a counter is provided in the circuit corresponding to the pulse processing circuit 37 in FIG. The signal is counted and the count is cleared by the C phase signal. When the respective count values of the second and subsequent axes match a predetermined setting value for each axis, each pulse processing circuit generates a synchronization start interrupt signal and starts synchronized operation.

〔Effect of the invention〕 As explained above, the present invention has the following effects.

1) By sampling the control loop from the second axis onwards at the timing determined by the output of the position detector of the first axis, and synchronizing the second axis onwards with the first axis,
Even if the speed of the axis changes, there is no need to change the sampling period for the second axis and thereafter, or to interpolate the target command, and it is also possible to cope with temporary speed fluctuations of the first axis.

2) Use an encoder that generates A, B, and C phase signals as a position detector for the first axis, and after the second axis and subsequent NC devices receive the C phase signal, a predetermined number of A phase signals are generated for each axis. , when the B-phase signal is received, by starting the synchronous operation of the relevant axes, it is possible to arbitrarily set the phase difference between each axis or between each axis and the first axis to perform synchronous operation.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a first embodiment of a multi-axis NC system to which the synchronous operation method of the present invention is applied, Fig. 2 is a block diagram of the NC device 12 of Fig. Figure 4 is a block diagram of a conventional example of a servo system that operates the second axis in synchronization with the first axis using a pulse train. The figure is a diagram to explain that when the speed of the main axis changes, a tracking error occurs for each axis after the second axis.
FIG. 5(a) shows an example of the target command value to be given to the control loop at each sampling time when the main shaft is rotating normally, and FIG. 5(c) is a diagram showing the interpolated target command value at each sampling time when the rotational speed of the spindle reaches 172. be. 1... Main axis (first axis) motor, 2... Second axis motor, 3... Third axis motor, 4...
・4th axis motor, 5... Main shaft encoder, 11...
・NC device for spindle, 12.13.14--NC device, 22.23.24--ball screw, 26.27.28--cutting tool, 31...memory, 32
．． 35-... Sampler, 33.41... Counter, 3
4--Subtractor, 36.37--Pulse processing circuit,
38-CPU, 39-D/A converter, 40-
...Speed controller, 42...Second axis motor, 43-
...Encoder.

Claims (2)

[Claims] (1) The first axis corresponds to the rotational position and direction of the first axis.
and a second signal and a third signal corresponding to the origin of the rotational position of the first axis, the timing of starting the synchronous operation of the second and subsequent axes is determined by at least the third signal, and the rotation of the first axis is determined by at least the third signal. By giving target commands for each axis after the second axis that are set corresponding to the position to each control loop, sampling control of the operation of each axis after the second axis is performed in synchronization with the rotation of the first axis. A synchronous operation method characterized in that the control loops of the second and subsequent axes are sampled at timings determined by first and second signals. (2) The first, second, and third signals are generated by an encoder and used as A, B, and C phase signals, and the number of A and B phase signals output after the output of the C phase signal is 2. The synchronous operation method according to claim 1, wherein when the values match the numerical values set for each axis after the second axis, the synchronous operation of the relevant axis is started.