JPS5831836B2 - Step motor deceleration control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the deceleration of a step motor having an encoder connected to its rotating shaft.

In the step motor control method, in which the step motor is feedback-controlled using feedback pulses from an encoder directly connected to the rotating shaft of the step motor, conventionally, as a deceleration method to stop the step motor from a constant speed, a predetermined deceleration method that does not rely on feedback pulses has been used. There are open-loop control deceleration methods that generate a drive signal that switches the excitation phase of the step motor at regular intervals, and deceleration methods that use feedbutter pulses.

Figure 1 shows a deceleration method using open-loop control.

In the case of this control method, the pulse interval from the start of deceleration to around 4 pulses, that is, the pulse interval of T1 to T4, is much shorter than the pulse interval of the self-starting pulse that allows the step motor to start, and the maximum Since the torque is close to the pulse interval of the response pulses and the torque is small, there is a drawback that disturbances are added or step-out occurs due to load fluctuations.

In the case of feedback control using feedback pulses, excitation continues until the feedback pulse is generated, so there is no chance of step-out.

Figure 2 shows a deceleration method using feedback pulses.

In the case of this control method, if there is a load change, especially if the load friction increases, the motor may stop at a position other than the stop position indicated by the feedback pulse 6.7 in FIG. 2.

The reason for this is a theory called so-called hoshicast control.

As described above, conventional deceleration methods have drawbacks in response to load fluctuations and disturbances.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to make it possible to stop at a predetermined stop position without stepping out even when load fluctuations or disturbances are applied.

The present invention decelerates by a feedback pulse at the initial stage of deceleration, and after decelerating by a predetermined step, the feet 2. P-pa~
The step motor is characterized by being decelerated and stopped at a predetermined position by open-loop control that generates pulses at intervals of 1, 2, 3, and 3.

FIG. 3 is a block diagram showing an embodiment of the configuration for implementing the deceleration control method of the present invention, and FIG. 4 is a timing chart for acceleration and constant speed.

For convenience, it is assumed that the step motor rotates eight steps to drive one space.

When the start signal is applied to the set terminal of the flip-flop 7, the flip-flop 7 is set, and its first output, that is, the acceleration signal 17, becomes logic 1.

When the acceleration signal 17 becomes logic 1, a start drive signal 16 is generated from the monostable multi piper (hereinafter referred to as mono multi) 8.

The start drive signal 16 is applied to the ring counter 3 via the OR gate 10 to rotate the step motor 1 by one step.

An encoder 2 directly connected to the step motor 1 generates one feedback pulse when the step motor 1 moves one step.

The step motor 1 is set to 1 by the start drive signal 16.
When a step motion occurs and a feed batter pulse is generated from the encoder 2, since the AND gate 9 is opened by the acceleration signal 17, it is applied to the ring counter 3 via the AND gate 9 and the OR gate 10, and further moves the step motor 1 one step. Rotate.

In this way, the stepper motor 1 is accelerated to a constant speed by the feedback pulse.

In this case, the speed of the step motor 1 can be determined by setting the position at which the feedback pulse of the encoder 2 is generated in one step of the step motor 1.

At the same time as the start signal is generated, the number of spaces is loaded into the loadable up/down counter 11.

When the output of the up/down counter 11 becomes 1, that is, when the step motor 1 rotates by the number of spaces obtained by subtracting 1 space from the specified number of spaces, the output of the Nant gate 12 becomes logic 0, and the flip-flop 7
is reset and the acceleration signal 17 becomes logic 0.

As a result, the AND gate 9 closes and the acceleration drive signal 15 is no longer generated.

When the acceleration signal 17 is logic O, the deceleration circuit 6 is enabled.

The timing chart is shown in FIG. 5, and the deceleration circuit 6
The details are shown in Figure 6.

After the acceleration signal 17 becomes logic O, a pulse with a time width t1 is generated from the monomulti 19 with the first feedback pulse, which is applied to the monomulti 29 through the invert-or gate 20, and then is applied to the monomulti 29 with a first time width t8. A deceleration drive signal 14 is generated.

That is, the deceleration drive signal 14 is generated 11 hours after the feedback pulse is generated, and the step motor 1 is
Apply negative torque to decelerate.

Similarly, after the feedback pulse is generated, L2
After st3vj4, a deceleration drive signal 14 is generated to gradually decelerate.

Monomulti 2 after t4 hours from the trigger of monomulti 25
6 generates a pulse with a time width t, and after t6 time, a deceleration drive signal 14 with a time width t6 is generated from the monomulti 30.

After t6 to t7, the deceleration drive signal 14 is generated regardless of the feedback pulse.

In this manner, the first four pulses are decelerated by feedback control after deceleration begins, and the remaining three pulses are decelerated by open loop control.

The point at which feedback control changes to open loop control is determined by the torque characteristics of step motor 1.

That is, the pulse interval generated by open-loop control must be set to a value that is longer than or close to the pulse interval of the self-starting pulse.

As described above, according to the present invention, even if load fluctuations or disturbances are applied, the motor can be stopped at a predetermined stop position without losing synchronization.

[Brief explanation of the drawing]

Fig. 1 is a timing chart showing the characteristics of the conventional deceleration method using open loop control, Fig. 2 is a timing chart showing the characteristics of the conventional deceleration method using feedback control, and Fig. 3 is a timing chart showing the characteristics of the conventional deceleration method using feedback control. A block diagram showing one embodiment of the configuration, FIG. 4 is a timing chart showing acceleration, FIG. 5 is a timing chart showing deceleration of the present invention, and FIG. 6 is a block diagram showing details of the deceleration circuit of FIG. 3. It is a diagram. In the figure, 1 is a step motor, 2 is an encoder, and 3 is a step motor.
is a ring counter, 4 is an octal counter, 5 is a decoder,
6 is a deceleration circuit, 7 is a flip-flop, 8, 19 and 2
3 to 30 are mono multi, 9 is and gate, 10.22
is an or gate, 11 is an up/down counter with load,
12 is a Nant gate, 13 is an inverter, 14 is a deceleration drive signal, 15 is an acceleration drive signal, 16 is a start drive signal, 17 is an acceleration signal, 18 is an invert and gate, and 20.21 is an invert or gate.

Claims (1)

[Claims] 1. In a step motor with an encoder connected to its rotating shaft, at the initial stage of deceleration, the excitation phase is switched by the feedback pulse from the encoder to perform deceleration control, and after deceleration by a predetermined step, the control is switched to open-loop control, and a preset gradual deceleration is performed. A deceleration control method characterized by deceleration control by switching the excitation phase at intervals that increase in length.