JP2730048B2 - Driving method of linear pulse motor - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a driving method of a linear pulse motor, and more particularly, to a method in which a moving element of a linear pulse motor is driven by a command pulse and follows a moving object having a certain amplitude. To a driving method in the case of performing control in (1).

(Prior Art) The application fields of pulse motors as servo motors or actuators in automation mechanisms have recently expanded, but the range of application is expected to expand in the future.

When a linear pulse motor is used as a servo motor or an actuator, and particularly when the moving element is controlled to follow a moving object having a certain amplitude, hysteresis characteristics are a problem with respect to the movement of the moving element. For example, various improvements have been made to floppy disk drives with the development of computers, and linear pulse motors are also used for driving magnetic heads. In a high-density floppy disk drive, the recording medium may cause eccentric motion due to expansion and contraction due to heat, chucking error, etc., and the linear pulse motor for driving the magnetic head completely follows this eccentric motion and corrects eccentricity. Must be done. In this case, even if the linear pulse motor is caused to reciprocate by minute feed by micro-step driving, the movement of the linear pulse motor with respect to the command input pulse is delayed due to hysteresis due to residual magnetism. The relationship between the command pulse when the linear pulse motor is driven by the micro step and the displacement of the moving element of the linear pulse motor will be described with reference to FIG.

FIG. 4 (a) shows the input state of the command pulse with the time t on the horizontal axis, and FIG. 4 (b) shows the number of command pulses on the horizontal axis.
The vertical axis shows the relationship between the command pulse and the displacement of the movable element by taking the displacement of the movable element. Now, as shown in FIG.
N-pulse for commanding forward movement is given to the mover at the zero displacement point to deflect in the forward direction, and then 2N pulses for commanding backward movement are given, and the deflecting is performed in the reverse direction. Then, if N pulses for commanding forward movement are given and the movable element is returned, the movable element should theoretically return to the point of zero displacement. However, the mover does not actually return to the zero excursion point. When this described in more detail in FIG. 4 (b), then excursion to X ₁ points mover giving N pulses to issue forward movement in the positive direction in the actual point of zero deflection current Then, when 2N pulses for instructing reverse movement are given and deviated in the reverse direction, the mover does not return to the zero deviation point but returns x ₁ (μm) in the Nth pulse. not enough. To return this to the zero deviation point, α of the remaining N reverse movement command pulses are required. Therefore, the displacement point of the mover due to 2N reverse movement command pulses is-
It does not reach X ₁ and stays at −X ₂ (X ₁ > X ₂ ). That point-X ₂
Is moved in the forward direction by the next N forward movement command pulses, but with these N pulses, the mover does not move to the zero deviation point, but returns by x ₂ (μm). Absent. To return to the zero deviation point, α ′ of the next N forward movement command pulses will be used.

FIG. 5 is a diagram showing the relationship between the displacement of the moving element and time. In FIG. 5, graph (a) shows the relationship between the theoretical displacement of the moving element due to the command pulse and time, and graph (b) shows the relationship between the actual displacement of the moving element and time. . That is, by giving N pulses for instructing the forward movement to deflect the mover to the forward direction, and then giving 2N pulses for instructing the backward movement, to deflect the mover in the reverse direction. In the case where the moving element is deflected in the positive direction by giving N pulses for commanding the next positive moving direction, the moving direction of the moving element is theoretically such that the moving direction is at time t (positive direction command pulse It switches from the forward direction to the reverse direction at the (Nth generation time), passes through the zero displacement point at time 2t (the first Nth generation time of the 2N reverse command pulses), and reaches the time 3t ( The direction is switched from the reverse direction to the positive direction at the second half of the 2N backward command pulses (at the time of the Nth occurrence of the second half), and at time 4t (at the time of the Nth occurrence of the next forward direction command pulse), the deviation becomes zero. You should reach the point. However, in practice the mover is displaced at time t to X ₁ for N pulses for instructing the first positive movement, where changing the movement direction, to command a backward movement of the next
A 2N number of 2t + t _1, rather than time 2t has the mover passes through the point of zero deflection in the opposite direction to the pulse, deviation point mover arrives with 2N-th pulse -X ₂ (X ₁ > X ₂ ), and the mover moves in the positive direction from the point by the N pulses for instructing the next positive direction movement, but does not reach the zero displacement point at time 4t. and reaches the N being moved by positive direction movement command pulse at time 4t + t ₂ of the point of zero deflection. In this way, the movement of the moving element has a hysteresis characteristic with respect to its deviation, so that the following movement of the moving element is delayed, making the control difficult.

(Problems to be Solved by the Invention) Accordingly, the problem to be solved by the present invention is to control the moving element of the linear pulse motor by a command pulse so as to follow a moving object having a certain amplitude. An object of the present invention is to provide a driving method for preventing a delay in a follower movement of a moving element.

(Means for Solving the Problems) According to the present invention, when a moving element of a linear pulse motor is driven by a command pulse and controlled to follow a moving object with a certain amplitude, the moving element is delayed by the following movement. Based on the idea that in order to prevent the occurrence of the noise, it is only necessary to eliminate the effect of the hysteresis characteristic on the displacement of the mover during micro-step driving, and to cancel the hysteresis by appropriately giving the input pulse. It is assumed that.

When the mover of a linear pulse motor is driven by a command pulse and is controlled to move following a moving object with a certain amplitude, a delay occurs in the follower movement of the mover due to the hysteresis characteristic of the mover. After being deviated in the forward direction by the N command pulses, when deflected in the reverse direction, the N command pulses do not return to the point of zero elementary deviation, and the next reverse command pulse This is because it depends on the generation time of the supplementary pulse, because some of the supplementary pulses are required. Therefore, according to the present invention, after the movable element is displaced in the positive direction by the number of command pulses corresponding to the amplitude, at the time of reversal, the number of incremental pulses corresponding to the amplitude is generated within a short time. The linear pulse motor is driven so that the increment pulse is added to the above-mentioned command pulse and the movable element is displaced in the reverse direction. As a result, the influence of the hysteresis characteristic on the displacement of the moving element is removed, and the above-mentioned object of preventing the following movement of the moving element from being delayed is achieved.

Preferably, according to the present invention, the relationship between the amplitude, the number of command pulses, and the number of incremental pulses is written in advance in a storage unit of the linear pulse motor driving device for various cases, and the amplitude is detected. The number of command pulses and the number of incremental pulses corresponding to the detected amplitude are configured to be automatically determined.

(Operation) According to the present invention, after the movable element is displaced in the positive direction by the number of command pulses corresponding to the amplitude to be followed, the number of incremental pulses corresponding to the amplitude is generated within a short time at the time of inversion. The command pulse is added to the command pulse and applied to deviate the movable element in the reverse direction, so that the movable element can follow the movement without delay.

(Embodiment) As described above, according to the present invention, in the case where the moving element of the linear pulse motor is driven by the command pulse and controlled so as to follow a moving object with a certain amplitude, the moving element is delayed by the following movement. Is based on the idea that it is only necessary to eliminate the influence of the hysteresis characteristic on the displacement of the moving element during microstep driving.

Therefore, according to the present invention, when the moving element of the linear pulse motor is moved to follow a moving object with a certain amplitude, the moving element is first shifted from the zero displacement point to the positive maximum value of the amplitude. When moving back to the point of the maximum value of the amplitude in the reverse direction and returning to the next zero point of deviation, first, as shown in FIG. N command pulses required for movement are given to deflect the mover in the forward direction, and then 2N + α _one pulse for commanding the reverse movement is given to deflect the mover in the reverse direction. And N + α ₂ pulses for commanding the forward movement are applied to deflect the mover in the positive direction, thereby returning the mover to the zero displacement point. Since the amount of hysteresis when no increasing pulse is added changes according to the moving amplitude of the moving element, that is, the number of command pulses, as shown in FIGS. 2 (a) and 2 (b), the number of increasing pulses α ₁ and α ₂ is It will change according to the moving amplitude of the mover.

Further, the generation time of α ₁ and α ₂ incremental pulses needs to be sufficiently shorter than the generation time of the basic command pulse. That is sufficiently small micro time than 2N + alpha ₁ single generation time of the pulse is the 2N pulses generated time and substantially alpha ₁ pulses occurrence time as unchanged in the time of occurrence of 2N pulses, The generation time of N + α ₂ pulses is N
The generation time of α ₂ pulses is set to be a very small time that is sufficiently smaller than the generation time of N pulses so as not to be substantially different from the generation time of the N pulses. For example, when a linear pulse motor is used for driving a magnetic head in a high-density floppy disk drive, the time for generating an incremental pulse is set to about several tens of microseconds in a follow-up movement for correcting the eccentricity of a moving element of the linear pulse motor. In this case, the period of the eccentric movement of the recording medium is about 100 msec, whereas if the time of generation of the incremental pulse is set to several tens μsec, the time of generation of the incremental pulse relative to the time of generation of the command pulse is a value to be ignored. There is substantially no delay in the follower movement of the moving element due to the generation of the incremental pulse. That is, in FIG. 1, the time for giving N basic command pulses is t
Assuming that the generation time of the incremental pulse is Δt and Δt << t, Δt〜0 may be considered, and the time for giving the basic command pulse and the time for giving the basic command pulse with the incremental pulse added are Is assumed to have substantially no delay, and thus no substantial delay in the displacement time of the mover due to the N basic pulses and the displacement time of the mover due to the addition of the incremental pulse to the basic pulse. Can be. This is because the movement of the movable element can be regarded as being performed without delay in the pulse generation time. Therefore, the increment pulse is generated at a higher frequency than the basic command pulse, and the generation time is reduced.

FIG. 3 is a diagram for explaining a process for executing the linear pulse motor driving method according to the present invention. In the figure, reference numeral 10 denotes a means for detecting the amount of amplitude by which the moving element should follow the moving element (for example, the amount of off-track when used for correcting the eccentricity of the recording medium in a high-density floppy disk drive), and 11 denotes this detection. determining the number and the number of incremental pulses of the command pulse corresponding to the amount, for example, as described above, the positive direction of the N pulses, reverse 2N + alpha ₁ pulses, the positive direction of the N + alpha ₂ pulses sequentially A pulse number determining and generating means for generating and transferring to a micro step driving circuit, wherein the relationship between the amplitude to be followed, the number of command pulses, and the number of incremental pulses is stored in the linear pulse motor driving means for various cases. Write in advance in the means,
The number of command pulses and the number of incremental pulses corresponding to the detected amplitude are automatically determined. The number of pulses transferred to the micro-step driving circuit is calculated by the counter 12, and digital signals representing current values corresponding to the counted values are read out from the ROM 13 and the ROM 13 ', and are respectively converted into digital / analog converters 14, 14. ′ And converted by the amplifiers 15 and 15 ′ into analog signals. As a command current, the A-phase coil 16 and the B-phase coil 1
Supplied to 6 '. That is, the micro-step driving circuit is a circuit for supplying currents Isinθ and Icosθ as shown in FIG. 3A to the A-phase coil 16 and the B-phase coil 16 ′, respectively. When the count value of the counter 12 is zero, the current at the point O in FIG. 3A flows, and when a positive pulse is given and the count value of the counter 12 indicates that, the A-phase coil
The currents applied to the 16 and B phase coils 16 'change in the positive direction in the figure, and when a pulse in the negative direction is given and the count value of the counter 12 indicates that, the A phase coil 16 and the B phase coil 16' Is changed in the negative direction in the figure, and continuous driving is performed. For this reason, the ROM 13 and the ROM 13 'store data that changes with a sine function and a cosine function, respectively.

(Effects of the Invention) According to the present invention, as described above, when the moving element of the linear pulse motor is driven by the command pulse and is controlled to follow a moving object with a certain amplitude, a minute pulse is generated when the pulse is inverted. By giving an incremental pulse generated at the time, the effect of the hysteresis characteristic can be canceled, and there is an effect that a delay does not occur in the follow-up movement of the moving element.

Note that the relationship between the amplitude to be followed, the number of command pulses, and the number of incremental pulses is written in advance in the storage means of the linear pulse motor driving device for various cases, and the above amplitude is detected, and the detected amplitude is corresponded. If the configuration is such that the number of command pulses and the number of incremental pulses to be performed can be automatically determined, the remarkable effect that the mover can completely follow any amount of amplitude without delay is achieved. Demonstrate.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the additional generation of an incremental pulse in the linear pulse motor driving method according to the present invention, and FIG. 2 is a diagram for explaining the relationship between the incremental pulse and the hysteresis characteristic. ) Shows the relationship between the number of pulses and the deviation, (b) shows the relationship between the amplitude, that is, the number of command pulses, and the amount of hysteresis, and FIG. 3 shows the configuration for implementing the linear pulse motor driving method according to the present invention. The figure showing the
FIG. 3A is a diagram showing currents flowing through the A-phase winding and the B-phase winding of the linear pulse motor, and FIG. 4 is a diagram for explaining a drawback in the conventional linear pulse motor driving method.
(A) is a diagram showing the relationship between the application of a command pulse and time,
FIG. 5B is a diagram showing a hysteresis characteristic, and FIG. 5 is a diagram for explaining a time delay in the follower movement of the moving element in the conventional linear pulse motor driving method. 10 tracking amplitude detecting means, 11 pulse number determining / generating means, 12 counter, 13, 13 'ROM, 14, 14' digital / analog converter, 15, 15 'amplifier , 16 ……
A-phase coil, 16 '... B-phase coil.

Claims (4)

(57) [Claims] When a moving element of a linear pulse motor is driven by a command pulse and is controlled to follow a moving object having a certain amplitude, the moving element is moved in a forward direction by a number of command pulses corresponding to the amplitude. After the deflection, the number of incremental pulses corresponding to the amplitude is generated within a short time at the time of inversion, the incremental pulse is calculated for the command pulse, and the movable element is deflected in the reverse direction, thereby moving. A method of driving a linear pulse motor, characterized in that an influence of hysteresis characteristics on displacement of a moving element is removed so that a delay does not occur in the following movement of the moving element. 2. The relationship between the amplitude, the number of command pulses, and the number of incremental pulses is written in advance in a storage means of a linear pulse motor driving device for various cases, and the amplitude is detected. 2. The driving method for a linear pulse motor according to claim 1, wherein the number of corresponding command pulses and the number of increment pulses can be automatically determined. 3. When the linear pulse motor is used for driving a magnetic head in a high-density floppy disk drive, and the movable element of the linear pulse motor follows the eccentric movement of the recording medium to perform eccentricity correction, After the mover is displaced in the positive direction by the number of command pulses corresponding to the amplitude of the eccentric movement, the number of incremental pulses corresponding to the amplitude is generated within a short time at the time of inversion and added to the command pulse. A driving method of the linear pulse motor, wherein the influence of the hysteresis characteristic relating to the displacement of the moving element is removed so as not to cause a delay in the following movement of the moving element. 4. The apparatus according to claim 3, wherein said incremental pulse is generated within a short time of about several tens of microseconds.
Driving method of the linear pulse motor described.