JP3161621B2 - Step motor operation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention operates with a drive pulse train for acceleration / deceleration control which includes an acceleration section from start to end of acceleration, a constant speed section from end of acceleration to start of deceleration, and a deceleration section from start of deceleration to stop. The operation method of the step motor to be performed.

[0002]

2. Description of the Related Art Generally, as a method of operating a step motor, a speed, that is, a drive pulse frequency is gradually increased from a stop state or a self-starting frequency, accelerated to a desired maximum speed, and then shifted to a constant speed state. An operation method of gradually decelerating from stop to stop is adopted. As an example showing the conventional operation method more specifically, an XY plotter using a step motor as a drive source for the X-axis and the Y-axis will be described. FIG. 5 schematically shows the internal structure of an XY plotter mechanism conventionally used in the CAD field and the like. In the figure, 10 is an X-axis step motor, 12 is a Y-axis step motor, 17 is an X-axis drive pulley, 18 is an X-axis drive belt, 1
9 is an X-axis idler pulley, 20 is an X-axis guide, 21 is X
Axis slider, 22 is a Y-axis drive pulley, 23 is a Y-axis drive belt, 24 is a Y-axis idler pulley, 25 is a Y-axis guide,
26 is a carriage, 27 is a recording pen, 28 is a platen,
Reference numeral 29 denotes a recording medium. Hereinafter, the operating principle of the XY plotter will be described with reference to FIG. When a drive pulse is input to the X-axis step motor 10, the X-axis drive pulley 17 directly connected to the rotation axis of the X-axis step motor 10 simultaneously rotates,
X-axis drive belt 1 wound around this X-axis drive pulley 17
8 moves around the freely rotating X-axis idler pulley 19. On the other hand, a part of the X-axis drive belt 18 is fixed to the X-axis slider 21, and as a result, the rotation amount of the X-axis step motor 10 is such that the Y-axis guide 25 fixed to the X-axis slider 21 moves linearly. Has been converted. At this time, the degree of resolution of the linear movement amount is controlled to be about 0.025 mm / step. In the Y-axis drive system, similarly to the X-axis, the rotation amount of the Y-axis step motor 12 is linearly converted by a Y-axis drive pulley 22, a Y-axis drive belt 23, and a Y-axis idler pulley 24, and fixed to the Y-axis drive belt 23. The carriage 26 can move on the Y-axis guide 25 with a resolution of about 0.025 mm. The X-axis and Y-axis drive pulses are generated by a two-axis simultaneous control algorithm by an arithmetic processing circuit inside the plotter, and the recording pen 2 held by the carriage 26
A desired trajectory is drawn on the recording medium 29 placed on the platen 28 by combining it with the intermittent up-down movement 7.

In the XY plotter having such a configuration, in order to reduce the cost of the apparatus, the XY plotter is operated by adopting an open-loop control method for driving control of a step motor serving as a drive source for the X-axis and the Y-axis. Because of the control method, there is no feedback of the current position, and a measure is taken in advance to completely prevent a position shift due to step-out caused by a vibration phenomenon of the step motor or the like. As a measure of such measures, in order to operate the step motor as high as possible, the acceleration section from the start to the maximum operable speed until the end of acceleration, the constant speed section from the end of acceleration to the start of deceleration, and the start of deceleration It is driven by a drive pulse train according to a predetermined trapezoidal acceleration / deceleration pattern consisting of a deceleration section from to a stop. Normally, the visual image drawn by the XY plotter is often represented by a set of short vectors. Therefore, it is necessary to shift to a constant speed in the acceleration section, that is, before reaching the maximum operable speed, further decelerate and stop. Is frequently done.

FIG. 6 shows an acceleration / deceleration pattern used for operation of a conventional step motor. P3 'is the acceleration / deceleration pattern when the arrival speed is V3, P4' is the acceleration / deceleration pattern when the arrival speed is V4, Pm is the acceleration / deceleration pattern when the maximum speed is Vm, t4 is the acceleration end time of the acceleration / deceleration pattern P3 ',
t6 is the acceleration end time of the acceleration / deceleration pattern P4 ', t9 is the acceleration end time of the acceleration / deceleration pattern Pm, t13 is the constant speed end time of the acceleration / deceleration pattern P3', and t14 is the acceleration / deceleration pattern P
4 ', the constant speed end time, t12 is the constant speed end time of the acceleration / deceleration pattern Pm, and (t13-t4) is the acceleration / deceleration pattern P3'.
(T14-t6) is the acceleration / deceleration pattern P4 '
Shows a constant speed section. In each case, the section from the constant speed end time to the stop indicates the deceleration section. In the conventional stepping motor operation method, (t13−t4) = (t14−t6) from the simplicity of the control algorithm.
Acceleration / deceleration patterns P3 'and P4'
In some cases, (t13−t4) = (t14−t6) =
A triangular acceleration / deceleration pattern of 0 has been adopted.

[0005]

However, at the transition inflection point from the acceleration section to the constant speed section and from the constant speed section to the deceleration section, an abrupt change in acceleration causes an unbalanced state in the equation of motion of the drive system. The unbalanced state is consumed as vibration energy. Particularly, the stepping motor is sensitive to the influence of the unstable phenomenon excited by the vibration energy, and the magnitude of the generated vibration and the settling time vary depending on the driving speed, that is, the frequency of the driving pulse.
FIG. 7 shows the relationship between the drive pulse frequency and the generated vibration amplitude G. In FIG. 7, f3 indicates a driving pulse frequency corresponding to the reaching speed V3, and f4 indicates a driving pulse frequency corresponding to the reaching speed V4. F4, that is, a region where the reaching speed V4 generates a large vibration. For this reason, if the length of the constant speed section is made constant as described above, depending on the operating speed, a transition from the constant speed section to the deceleration section occurs before the vibration is settled,
A large vibration is generated again at the inflection point (for example, time t14), and in some cases, this vibration causes a step-out phenomenon of the step motor, so that the current position cannot be managed and the reliability of the XY plotter is significantly impaired. was there. on the other hand,
In some cases, a constant speed section having a certain length with a sufficient margin for the vibration settling may be provided in advance, but in this case, the extra constant speed section has a drawback of lowering the throughput of the drawing operation. The above-mentioned drawbacks have arisen from the fact that a sufficient study has not been made particularly on the optimization of the acceleration / deceleration pattern in the operation method of the step motor used as the drive source for the X-axis and the Y-axis. Therefore, the acceleration / deceleration pattern in the stepping motor driving method seen in the conventional example is improved, and in particular, the length of the constant speed section after shifting from the acceleration section to the constant speed section is optimized to improve the positioning operation throughput, An object of the present invention is to realize a method of operating a step motor that can operate at high speed while improving the reliability of management.

[0006]

[Means for Solving the Problems] In order to solve the above problems, a stepping motor whose vibration characteristic with respect to speed is known in advance is used as a drive source, and an acceleration section from start to end of acceleration and a constant speed from end of acceleration to start of deceleration are set. In an acceleration / deceleration pattern consisting of a section and a deceleration section from deceleration start to stop, when shifting to a constant speed section having an arrival speed lower than the maximum speed in the middle of the acceleration section reaching the maximum speed, the length of the constant speed section is reduced. In the method of operating a stepping motor driven by a drive pulse train whose height is increased in accordance with an increase in the reaching speed, a constant speed of a known speed at which vibration becomes large in the middle of an acceleration section reaching the maximum operable speed. Steps in an acceleration / deceleration pattern in which the length of the constant speed section is changed to be longer than the constant speed section of other speeds increased according to the increase of the reaching speed that does not reach the maximum speed when shifting to the section We are driving over data.

[0007]

By using such an operation method, the constant speed section is shortened in a low speed region where the generated torque of the step motor has a margin, thereby improving the positioning operation throughput. In order to change the length of the constant speed section depending on the speed, it is possible to settle the vibration generated during the transition from the acceleration section to the constant speed section to a predetermined amount and then shift to the deceleration section. The stepping motor operation method that has been improved with these series of steps while preventing the stepping out of the stepping motor by suppressing the vibration in the step, improving the reliability of the position management, and minimizing the decrease in the throughput of the positioning operation. Can be realized.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to more specifically describe one embodiment of the present invention, as in the description of the prior art, a description will be given with reference to an example in which a stepping motor is applied to a driving source of an XY plotter in a printing apparatus. FIG. 1 shows an acceleration / deceleration pattern used in the method of operating a step motor according to the present invention. P1 is the arrival speed V
1, P2 is the acceleration / deceleration pattern when the arrival speed is V2, P3 is the acceleration / deceleration pattern when the arrival speed is V3, P4 is the acceleration / deceleration pattern when the arrival speed is V4, and P5 is the acceleration / deceleration pattern. Acceleration / deceleration pattern, Pm
Acceleration / deceleration pattern when is the maximum operable speed Vm, t
1 is the acceleration end time of the acceleration / deceleration pattern P1, t3 is the acceleration end time of the acceleration / deceleration pattern P2, and t4 is the acceleration / deceleration pattern P
3, t6 is the acceleration end time of the acceleration / deceleration pattern P4, t7 is the acceleration end time of the acceleration / deceleration pattern P5, t
9 is the acceleration end time of the acceleration / deceleration pattern Pm, t2 is the constant speed end time of the acceleration / deceleration pattern P1, and t5 is the acceleration / deceleration pattern P
2, a constant speed end time t8 is the constant speed end time of the acceleration / deceleration pattern P3, t10 'is a constant speed end time before the change of the acceleration / deceleration pattern P4, t10 is an extended constant speed end time of the acceleration / deceleration pattern P4, t11 is the constant speed end time of the acceleration / deceleration pattern P5, t12 is the constant speed end time of the acceleration / deceleration pattern Pm, (t
2-t1) is a constant speed section of the acceleration / deceleration pattern P1, and (t5-
t3) is a constant speed section of the acceleration / deceleration pattern P2, and (t8−t)
4) is a constant speed section of the acceleration / deceleration pattern P3, and (t10'-t)
6) is a constant speed section before the change of the acceleration / deceleration pattern P4, and (t1)
0-t6) is a constant speed section after the extension of the acceleration / deceleration pattern P4,
(T11-t7) is a constant speed section of the acceleration / deceleration pattern P5,
(T12-t9) indicates a constant speed section of the acceleration / deceleration pattern Pm. In each of the acceleration / deceleration patterns, a section from the constant speed end time to the stop at the speed 0 indicates a deceleration section. C indicates an increase curve in the constant speed section.

The predetermined length of the constant speed section employed when the XY plotter shifts to the constant speed section in the middle of the acceleration section reaching the maximum drawing speed for drawing the short vector is determined by the values of the reaching speeds V1 to V5. (T2-t1) <(t5-t3) <(t8-t4) <along the increasing curve C in the constant speed section according to
(T10'-t6) <(t11-t7). Here, the relationship between the generated torque of the stepping motor driven at various speeds and the driving pulse frequency is as shown in FIG. 3, where PI is the drawing torque curve of the stepping motor, PO is the escape torque curve, and L is as shown in FIG. Shows the torque required to drive the load when the stepping motor is driven in a trapezoidal acceleration / deceleration pattern.
The drive pulse frequency to achieve m is shown. Generally, when the stepping motor is accelerated / decelerated as shown in FIG. 1, the generated torque of the stepping motor is shown by an escape torque curve. When the driving pulse frequency is low, the generated torque has a large margin with respect to the required torque L. Drive pulse frequency is fm
, The torque margin decreases. That is, there is a sufficient torque margin in a region where the driving pulse frequency is low, and in a low speed region, the step-out phenomenon of the step motor can be prevented even if the constant speed section is shortened. In particular, shortening the constant speed section in the low speed region is extremely effective for improving the throughput when frequent fine positioning operations such as short vectors are performed.

Generally, when a predetermined load is connected to a stepping motor and the motor is driven at various speeds, that is, at a driving pulse frequency, the vibration characteristics at the time of driving at each speed can be grasped in advance as shown in FIG. In the case shown in FIG. 1, the trajectory of the acceleration / deceleration pattern P4 has a vibration trajectory larger than normal in the vicinity of the arrival speed V4, that is, the drive pulse frequency f4. −t6) to extend the length of the constant speed section to perform optimization. FIG. 2 is an enlarged view of an acceleration / deceleration pattern P3 and an acceleration / deceleration pattern P4 in FIG.
The dashed line indicates the operation trajectory of the step motor driven in these acceleration / deceleration patterns. In the same figure, when shifting from the acceleration section to the constant speed section of the arrival speed V4, a large vibration is generated by the step motor, so that the length of the constant speed section is extended until this vibration is settled to a predetermined amount. Deceleration pattern P4
Are formed. As a result, it is possible to shift from the constant speed section to the deceleration section at time t10 without being affected by the residual vibration of the vibration generated at time t6,
In normal short vector drawing, a constant speed section length along the increasing curve C of the constant speed section is adopted, and an acceleration / deceleration pattern is formed so as to minimize a decrease in the throughput of the drawing operation due to extension of the constant speed section. I have.

FIG. 4 shows an internal control circuit of a recording apparatus employing the stepping motor driving method according to the present invention. The XY plotter mechanism used in the description of the embodiment of the present invention is the same as the mechanism in FIG. 5 used in the description of the conventional example. In FIG. 4, 1 is an XY plotter, 2 is a host computer, 3 is an interface circuit, 4 is a communication control circuit, 5
Denotes a CPU (arithmetic processing unit), 6 denotes a RAM (read / write storage circuit), 7 denotes a ROM (read-only storage circuit), 8
Is an input / output control circuit (a), 9 is an X-axis motor control circuit,
0 is an X-axis step motor, 11 is a Y-axis motor control circuit,
12 is a Y-axis step motor, 13 is a pen up / down control circuit,
Reference numeral 14 denotes a pen vertical drive solenoid, 15 denotes an input / output control circuit (b), and 16 denotes a manual operation means.

The internal control of the XY plotter 1 is sequentially executed by the CPU 5 according to a control program stored in the ROM 7, and a series of processing operations are as follows. Interface circuit 3 of XY plotter 1 from host computer 2
The drawing data input via the CPU is temporarily stored in the RAM 6 via the communication control circuit 4 and sequentially read out and analyzed by the CPU 5. The arrival speed, the acceleration section, the constant speed section, and the deceleration section are designated based on the length of.
When these processes are completed, linear interpolation is performed so as to generate a predetermined vector according to the specified acceleration / deceleration pattern. At this time, time control data for generating a predetermined acceleration / deceleration pattern is stored in the ROM 7 in advance, and by performing a linear interpolation process with reference to the time control data, the X-axis step motor 10 and the Y-axis step motor A drive pulse train for operating the drive 12 is generated. The generated drive pulse train is subjected to power amplification by an X-axis motor control circuit 9 and a Y-axis motor control circuit 11 via an input / output control circuit (B) 8, and then an X-axis step motor 10 and a Y-axis step motor Twelve excitation energizations are performed. Each drawing vector contains information on the pen up-down operation, and simultaneously with the operation of the X-axis and Y-axis step motors 10 and 12, the pen up-down control circuit 13
, The pen vertical drive solenoid is driven, the recording pen is moved up and down, and a visual image is formed on the recording medium 29.

In the process of performing such a series of drawing processing,
The acceleration section, the constant speed section, the deceleration section, and the arrival speed at which the step motor is operated can be calculated from the length of the vector to be plotted, and the constant speed section length can be calculated along the increasing curve C of the constant speed section in FIG. The settings are made. If the calculation result of the reaching speed matches the reaching speed V4, a measure to extend the constant speed section is taken. The specified speed can be determined in advance in consideration of the vibration characteristics of the step motor as shown in FIG. 7, and in a speed range where the vibration amplitude is large, the vibration settles down to a predetermined amount. The acceleration / deceleration pattern is determined so as to extend the constant speed section up to. Also, in order to improve the throughput of the drawing operation, the shorter the length of the constant speed section adopted when shifting to the constant speed section in the middle of the acceleration section reaching the maximum drawing speed to draw the short vector, the shorter the shorter, the shorter It is effective, that is, when shifting to the constant speed in the middle of the acceleration section reaching the maximum speed and further decelerating and stopping, the method of driving the acceleration / deceleration with the acceleration / deceleration pattern in which the length of the constant speed section is changed according to the reaching speed Is taken. As a result, in the drawing of a normal short vector, an acceleration / deceleration pattern in which a constant speed section having a predetermined length according to the value of the reaching speed is provided and the length of the constant speed section is changed only at a specific reaching speed. Thus, the step motors for driving the respective axes can be operated.

[0014]

[Effect] By using the operation method as described above, the constant-speed section is shortened in a low-speed region where the generated torque of the step motor has a margin, thereby improving the throughput of the positioning operation, and further, the step motor is specified to be sensitive to vibration. In order to change the length of the constant speed section depending on the speed, it is possible to move to the deceleration section after the vibration generated when moving from the acceleration section to the constant speed section settles to a predetermined amount, and move to the deceleration section A step motor operating method that has improved the position of the step motor by controlling the vibration at the time to prevent step-out of the step motor and improve the reliability of the position management. Can be realized.

[0015]

[Brief description of the drawings]

FIG. 1 shows an acceleration / deceleration pattern of a step motor according to an embodiment of the present invention.

FIG. 2 shows a relationship between a generated torque of a step motor and a drive pulse frequency.

FIG. 3 is an enlarged view of an acceleration / deceleration pattern of a step motor according to an embodiment of the present invention.

FIG. 4 shows an internal control circuit of a printing apparatus that specifically adopts an embodiment of the present invention.

FIG. 5 shows a schematic structure of an XY plotter mechanism.

FIG. 6 shows an acceleration / deceleration pattern of a step motor according to a conventional example.

FIG. 7 shows a relationship between a driving pulse frequency of a step motor and a generated vibration amplitude G.

[Explanation of symbols]

 1: XY plotter 2: host computer 5: CPU 6: RAM 7: ROM 8: input / output control circuit (a) 9: X-axis motor control circuit 10: X-axis step motor 11: Y-axis motor control circuit 12: Y-axis Step motor 27: Recording pen 28: Platen 29: Recording medium P1 to P5: Acceleration / deceleration pattern of reaching speeds V1 to V5 Pm: Acceleration / deceleration pattern of maximum speed Vm

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-212999 (JP, A) JP-A-5-219799 (JP, A) JP-A-6-98598 (JP, A) JP-A-59-1984 132796 (JP, A) JP-A-60-16192 (JP, A) JP-A-61-20105 (JP, A) JP-A-63-63988 (JP, A) Japanese Utility Model 63-55800 (JP, U) JP-B-60-47836 (JP, B2) JP-B-60-29121 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 8/00-8/42 G05D 3/00 -3/20 B43L 13/00

Claims (1)

(57) [Claims] 1. A stepping motor whose vibration characteristic with respect to speed is known in advance is a drive source, and includes an acceleration section from start to acceleration end, a constant speed section from acceleration end to deceleration start, and a deceleration section from deceleration start to stop. In the acceleration / deceleration pattern, when shifting to a constant speed section having an arrival speed lower than the maximum speed in the middle of an acceleration section reaching the maximum speed, the length of the constant speed section is increased according to an increase in the arrival speed. in the method of operating the stepping motor is driven by the drive pulse train, luck
In the middle of the acceleration section that reaches the maximum speed at which the vehicle can roll, the length of the constant-speed section when shifting to a constant-speed section with a known speed at which the vibration increases is increased according to the increase in the reaching speed that does not reach the maximum speed. Increase
Step motor operating method being characterized in that driving the step motor at acceleration and deceleration pattern to be changed longer than the constant speed of the other speed is pressurized.