JP2003047283A - Drive controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive controller which optionally controls the velocity of a motor and can let the motor take a complicated motion. SOLUTION: This drive controller has a scale which has a plurality of patterns different in pulse width, a detection head which applies light to that scale and detects the luminous flux via that scale and detects the information about relative transition with that scale, a drive means which performs the relative transition between that scale and that detection head, and a control means which drives that drive means by generating drive pulses concerned with the quantity of relative transition between that scale and that detection head.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device, and more particularly to driving a displacement object and a motor for irradiating the displacement object (optical scale) with light through the displacement object and driving the displacement object. This is suitable for obtaining a physical quantity of displacement information such as rotation information and movement information of the means and smoothly performing relative displacement.

[0002]

2. Description of the Related Art Conventionally, an NC machine tool or the like has a rotary encoder, a linear encoder, or the like for detecting displacement information such as movement amount, rotation amount of an object (displacement object) and drive information of a motor for driving the object. Is used.

FIG. 5 is a schematic view of a main part of a conventional linear scale type optical encoder.

In FIG. 5, 101 is a slider 103.
It is a U-shaped detection head fixed to. Reference numeral 102 denotes a scale in which a groove has been processed.
(107a, 107b) and screws 108 (108a, 1)
It is fixed to the base 106 by 08b). 104
Is a motor for moving the slider 103 accumulated on the ball screw 105. Reference numeral 109 supports the motor 104 and the ball screw 105 and also serves as a mechanical stopper of the slider 103. Further, the number of pulses of the feed amount is counted by a control box (not shown), and the motor 10
Send command to 4. When the slider 103 moves, the detection head 101 obtains a periodic signal based on the scale 102. Scale 1 using the periodic signal obtained at this time
The displacement information of the slider 103 with respect to 02 is detected.

FIG. 6 is a schematic view of a main part of a conventional rotary scale type encoder. A detection head 121 is attached to an optical base (not shown). A rotary scale 122 is mounted on the shaft of the motor 123. Reference numeral 124 is a mechanical stopper. Reference numeral 125 indicates a stopper attachment. A control BO (not shown)
The number of pulses of the feed amount is counted by X, and a command is sent to the motor 123. The rotation information of the rotary scale 122 is detected using the periodic signal obtained by the detection head 121.

[0006]

In the conventional linear scale type or rotary scale type encoder, the groove pitch (grid pitch) processed in the scale is the same (uniform) in all the moving ranges. The scale 102 and the detection head 101 are moved relative to each other on the basis of one groove pitch. For this reason, it is difficult to change the rotation speed of the motor (that is, change the speed of the slider), and the degree of freedom in design has been narrowed.

At the end of the operating range, the motor may be given a sudden stop command, and in many cases, the slider may overrun.

For this reason, usually, a structure is used in which a slider is forcibly stopped by providing a mechanical stopper at a portion slightly ahead of the stop end of the scale. However, vibration and impact when the slider hits the stopper causes the position of the detection member including the scale to be displaced, and the life of the detection head, which is an optical component, to be shortened.

Further, even when the movable member once stopped at the end begins to move in the reverse direction (reverse rotation direction) again, vibration or impact may occur unless a smooth speed increase is realized.

In order to avoid these problems, there is a method of stopping the slider without vibrating it by, for example, a shock absorber. However, this method requires new space.

Further, only the end portion is a motor (actuator)
There is also a method of reducing the speed by controlling the voltage and frequency of the odor. However, this method causes the control system to become more complicated, resulting in an increase in cost.

It is an object of the present invention to provide a drive control device which can easily change the speed of a movable member without changing the voltage or frequency sent to a driving means such as a motor.

Another object of the present invention is to provide a drive control device in which smooth movement can be easily obtained by gradually increasing or decreasing the speed of the movable member and controlling the speed arbitrarily.

Another object of the present invention is to provide a drive control device capable of driving and controlling a movable member with almost no vibration and impact in a predetermined space without relying on a mechanical stopper or shock absorber. To do.

[0015]

According to a first aspect of the present invention, there is provided a drive control device, wherein a scale having a plurality of patterns having different pulse widths, the scale is irradiated with light, and a light flux passing through the scale is detected. , A detection head for detecting relative displacement information with respect to the scale, a drive means for performing relative displacement between the scale and the detection head, and a drive pulse relating to an amount of relative displacement between the scale and the detection head And a control means for driving the drive means.

According to a second aspect of the present invention, in the first aspect, the pulse width on the scale changes continuously or stepwise along the relative displacement direction of the scale and the detection head. Is characterized by.

According to a third aspect of the present invention, in the first or second aspect of the invention, the driving means drives the scale and the detection head so that the time required for relative displacement of one pulse width becomes substantially equal. It is characterized by being.

According to a fourth aspect of the present invention, in the first, second or third aspect, the pulse width of the scale is closer to the end side than the center side in the relative displacement range of the scale and the detection head. It is characterized in that it becomes smaller continuously or stepwise as it goes.

A fifth aspect of the present invention is characterized in that, in the first aspect, the scale has a uniform region having a uniform pulse width and a non-uniform region in which the pulse width continuously changes. .

According to a sixth aspect of the invention, in the fifth aspect of the invention, the control means gives acceleration / deceleration information to the driving means when the detection head and the scale are non-uniformly displaced relative to each other. It is characterized by that.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of the essential portions of a first embodiment of the present invention. 2 is a sectional view taken along line AA of FIG.

In FIGS. 1 and 2, reference numeral 101 is a U-shaped detection head, which is fixed to a slider (movable member) 103. The U-shaped detection head 101 has a light projecting means and a light receiving means.

Reference numeral 102 denotes a scale, on the surface of which a groove or a lattice pattern forming a pulse width is processed. After the scale 102 is aligned with the detection head 101, the left and right spacers 107 (107a, 1a) are attached to both ends.
07b) and screws 108 (108a, 108b) are fixed to the base (substrate) 106.

Reference numeral 104 denotes a driving means (motor) which drives the slider 103 accumulated on the ball screw 105 to reciprocate in one direction.

Reference numeral 109 (109a, 109b) denotes a mechanical stopper which supports the motor 104 and the ball screw 105 and limits the drive range of the slider 103.

Reference numeral 110 is a control means, and the slider 10
The number of pulses of the feed amount of 3 is counted and the motor 10
The drive pulse signal is sent to 4.

The width of the pulse groove of the scale 102 is gradually narrowed toward both ends as compared with the central portion.
Accordingly, even if the control means 110 gives a command to the motor 104 to move the same number of pulses within the same time, there is a difference in resolution. Therefore, the slider 103 (detection head 101) is on the scale 102 and the central portion is relatively fast. It becomes faster and becomes slower toward the end. In this embodiment, the time for the slider to move one pulse width is set to be substantially constant over the entire moving range.

Further, the detection head 101 is once scale 10
The pulse width is set so that the speed is gradually increased even when the slider 103 is stopped at the end of No. 2 and driven in the opposite direction again, and the speed becomes constant after the slider 103 has advanced a certain distance.

That is, the pulse density of the groove portion of the scale 102 is widened in the central portion and gradually narrowed toward both ends so that the voltage and frequency of the motor 104 are changed between the central portion and the end portions. This makes it easy to prevent overrun and vibration shock at the end of the slider without adopting any control method.

The drive control device of the first embodiment can be applied to, for example, a print head feeding mechanism of a printer. That is, the constant speed portion having a high speed is used only in the printing range, and the limit portion (end portion) can be moved in the reverse direction without giving a shock to the detection head as much as possible.

In the present embodiment, the scale 102
May have a region where the pulse width is uniform and a non-uniform region where the pulse width gradually changes.

Further, the control means 110 outputs specific acceleration / deceleration information so that the speed of the detection head in the non-uniform area is controlled.
May be given to the driving means.

In the present embodiment, the detection head 101 may be fixed on the substrate 106, and the scale 102 may be provided on a part of the slider 103 to control the driving of the slider 103.

FIG. 3 is an explanatory diagram of the detection head used in this embodiment.

In the figure, the light flux from the light source 301 passes through an aperture provided in the substrate 302, and then a scale as a displacement object provided with a radiation grating (linear grating) having a pulse width as a substantially parallel light flux in the lens system 303. It is incident on the first region 102 a of the light beam 102.

The ± n-order diffracted light diffracted by the grating of the first region 102a of the scale 102 is transmitted through the lens system 305, the corner cube 306, and the lens system 307 to the grating array of the scale 102 at different positions in the vertical direction. The light is guided to the second region 102b and an interference pattern is formed on the surface. The light flux based on the interference pattern that has passed through the second region 102b is condensed by the lens system 308 and detected by the light receiving element 309.

At this time, when the detection head 101 moves in the direction of the arrow 304, the interference pattern formed on the scale 102 is displaced in the opposite direction. Therefore, in the light receiving element 309, a signal having a period twice the grating resolution (grating pitch). Is obtained.

The displacement information of the slider 103 with respect to the scale 102 is obtained using the periodic signal obtained by the light receiving element 309.

As described above, in this embodiment, as the pattern shape provided on the scale, the portions having different pulse widths are provided.

As a result, the speed of the motor can be changed even in a simple drive control system in which signals having the same number of pulses are sent to the motor within the same time. .

Further, the speed fluctuation is smoothed by gradually widening or narrowing the pulse width of the scale.

Further, in the driving range, the pulse width of the central portion on the scale is widened and gradually narrowed toward the end portion so that the end portion is not affected by a mechanical cushion mechanism such as a shock absorber. This enables smooth deceleration and acceleration, and prevents displacement and damage of the detection head, etc. due to vibration impact, etc., and shortening of the life of optical parts.

FIG. 4 is a top view of the essential portions of Embodiment 2 of the present invention.

The present embodiment shows a case where the drive control device is applied to drive control of a robot arm.

Reference numeral 201 denotes a robot arm, which rotates about a rotary shaft 201a as indicated by an arrow. A motor 202 rotates the robot arm 201.
203 is a rotary type scale. Scale 20
The pulse width of 3 differs depending on the driving range of the robot arm 201.

A detection head (not shown) is attached to the robot arm 201 after alignment with the scale 203. 204A and 204B are mechanical stoppers for preventing runaway of the robot arm 201.

The pulse width of the scale 203 is gradually narrowed as it approaches the stop position (left and right ends of rotation). For this reason, the robot arm 201 moves only in the vicinity of the stop position, so that the parts chucked by the robot arm 201 can be moved safely and accurately without significantly reducing the tact time.

[0048]

According to the present invention, it is possible to achieve a drive control device capable of easily changing the speed of a movable member without changing the voltage or frequency sent to the driving means such as a motor.

In addition, according to the present invention, it is possible to achieve a drive control device in which smooth movement can be easily obtained by gradually increasing or decreasing the speed of the movable member and controlling the speed arbitrarily.

In addition to the above, according to the present invention, there is achieved a drive control device capable of driving and controlling a movable member with almost no vibration shock in a predetermined space without being swayed by a mechanical stopper, a shock absorber or the like. be able to.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

2 is a sectional view taken along line AA of FIG.

3 is an explanatory view of the detection head of FIG.

FIG. 4 is a schematic view of a main part of a second embodiment of the present invention.

FIG. 5 is an explanatory diagram of a conventional linear encoder.

FIG. 6 is an explanatory diagram of a conventional rotary encoder.

[Explanation of symbols]

101 detection head 102 scale 103 slider 104 motor 105 ball screw 106 base 107 Spacer 108 screw 109 stopper 201 robot arm 202 motor 203 rotary scale 301 light source 302 opening 303, 305, 307, 308 lenses 306 corner cube 309 Light receiving element

Claims (6)

[Claims] 1. A scale having a plurality of patterns having different pulse widths, and a detection head for irradiating the scale with light, detecting a light beam passing through the scale, and detecting relative displacement information with respect to the scale. A driving means for performing relative displacement between the scale and the detection head, and a control means for generating a drive pulse related to the relative displacement amount between the scale and the detection head to drive the driving means. A drive control device characterized in that 2. The pulse width on the scale changes continuously or stepwise along the relative displacement direction of the scale and the detection head.
Drive controller. 3. The drive according to claim 1, wherein the drive means drives the scale and the detection head so that the time required for relative displacement of one pulse width is substantially equal. Control device. 4. The pulse width of the scale is reduced continuously or stepwise toward the end side of the relative displacement range between the scale and the detection head as compared to the center side. The drive control device according to claim 1, 2, or 3. 5. The drive control device according to claim 1, wherein the scale has a uniform region having a uniform pulse width and a non-uniform region having a continuous pulse width variation. 6. The control means applies acceleration / deceleration information to the driving means when the detection head and the scale are non-uniformly displaced relative to each other.
Drive controller.