JPH01415A - Rotation angle detection device with rotation regulation mechanism - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a rotation angle detection device for detecting the absolute rotation angle of each rotary axis in an industrial robot, etc. The present invention relates to a rotation angle detection device equipped with a rotation regulation mechanism that regulates the rotation of a rotation shaft to be detected.

[Prior Art] Generally, when controlling an industrial robot, etc., a detection device is required to detect the rotation angle of each rotation axis of the arm etc. with high precision, and such a rotation angle detection device is , an incremental type detection device that is low cost and has a simple structure is generally used. Such a rotation angle detection device uses an incremental encoder, and after first performing a home alignment operation, the incremental signal from the incremental encoder is counted as an absolute rotation angle signal by an up/down counter to detect the absolute rotation angle. ing.

However, before starting detection or restarting detection after the power is turned off, the up/down counter is reset, so it is necessary to perform home alignment. , the robot arm and the like are required to make complicated movements, which poses a high risk of damaging the robot and peripheral equipment, and it is desired to eliminate the need for such home alignment operations.

Therefore, conventionally, when the power is turned off after home alignment, the incremental signal is used as rotation angle data.
RAM stored in non-volatile memory (bubble memory, EEPROM, etc.) or backed up by a battery
A method is used to store it in a

In this case, when you turn on the power again and resume detection,
The rotation angle data stored in the memory is forcibly transferred to the up/down counter, or the counter value from the up/down counter is corrected using the rotation angle data.

[Problems to be Solved by the Invention] However, in the conventional rotation angle detection device described above, even if the robot arm is braked with a brake attached to the drive motor etc. when the power is turned off, the robot arm does not touch the worker or the like. It may rotate due to contact or gravitational moment.
In such a case, even if the rotation angle is small, errors will accumulate and the detection accuracy will be greatly reduced, making it necessary to perform complicated home position alignment when the power is turned on again.

In other words, just by providing a memory as described above, although the number of times of origin alignment can be reduced, it cannot be completely eliminated.

Therefore, it is conceivable to provide a brake with a sufficiently large braking force so that the arm does not completely rotate during the power-off period, but in this case, the brake would be large and expensive.

The present invention aims to solve such problems by making it possible to regulate the rotation angle of the rotating member that occurs between when the power is turned off and when the power is turned on again, within a predetermined angle range. It is an object of the present invention to provide a rotation angle detection device with a rotation regulating mechanism that improves the accuracy of detecting an absolute rotation angle.

[Means for Solving the Problems] Therefore, the rotation angle detection device with a rotation regulating mechanism of the present invention has the following features:1. A plate-shaped drum is provided on the rotating shaft of the rotating member whose absolute rotation angle is to be detected, and a plurality of notches or protrusions are provided at equal angular intervals on the outer periphery of the drum. The device is provided with a regulating member that can fit into or come into contact with the rotating shaft to regulate the rotation of the rotating shaft, and a spring that biases the regulating member toward the outer periphery of the drum when the power of the device is turned off.

[Function] In the above-mentioned rotation angle detection device with a rotation regulating mechanism of the present invention,
When the device is powered off, the regulating member is urged toward the outer periphery of the drum by the biasing force of the spring. The rotation angle is regulated when it fits into or abuts the notch or protrusion in the section, and the rotation angle is reliably within a predetermined angular range.

[Embodiments of the Invention] A rotation angle detection device with a rotation regulating mechanism as an embodiment of the present invention will be explained below with reference to the drawings. Fig. 1 is a longitudinal cross-sectional view showing the rotation regulating mechanism, and Fig. 2 is a longitudinal cross-sectional view showing the rotation regulating mechanism. FIG. 3, a front view of the regulating mechanism, is a block diagram showing the overall configuration of this device.

First, the overall configuration of the rotation angle detection device of this embodiment will be explained with reference to FIG. In Fig. 3, 1 is an arm of an industrial robot or the like as a rotating member, 1a is a rotating shaft of the arm 1, 2 is a reducer, and 3 is an arm connected to the arm via the reducer 2.
A motor 4 for rotationally driving the arm 1 is connected to the rotating shaft 1a of the arm 1 via the reducer 2 and the motor 3 to rotate at a predetermined rotation angle (
In this embodiment, a resolver 5 serves as a rotation angle detection means for detecting an absolute rotation angle (θ) within one rotation, that is, 360°, and a driver 5 excites the resolver 4. Also.

6 is a resolver/digital (R/D) converter that converts the detection signal from the resolver 4 into a digital signal, and 7 is a pulse generator that converts the detection signal from the resolver 4 into a pulse.

This is a resolver/pulse (R/P) converter that converts into an incremental signal with B and Z phases. Here, the Z-phase pulse signal is for setting the origin, and the A and B-phase pulse signals are output with a 90° phase difference, and the direction of rotation can be detected by looking at the relationship between these pulse signals. It has become so.

8 is an up/down counter, and A from the R/P converter 7
, the B-phase pulse signal is counted, and the absolute rotation angle within one rotation of the motor 3 is divided into 256 8 bits, and the lower bit 2 is calculated.
A and B phase pulse signals (a Z phase pulse signal may also be used) are output from the R/P converter 7 every rotation of the motor 3, that is, every 256 pulses. It is counted and output as the absolute rotation number of the motor 3 in upper bits 2s to 215.

9 is a storage means for storing the detection signal (absolute rotation angle within one revolution) from the resolver 4 at that point in time when the power is turned off as a count value for the lower bits 2° to 27 from the up/down counter 8. first memory, 1
0 is the up/down counter 8 at that point when the power is turned off.
11 is a comparator, and the actual detection from the resolver 4 is digitized by the R/D converter 6 when the power is turned on again. The signal is compared with the power-off detection signal stored in the first memory 9. Further, 12 is a corrector, which converts the power-off count value stored in the second memory 10 into an actual count value corresponding to the actual absolute rotation speed according to the comparison result from the comparator 11 (details will be described later). After the correction value is corrected, the correction value is set in the upper bits 2' to 21s of the up/down counter 8.

Note that in the device of this embodiment, when the power is turned on again, the actual detection signal from the resolver 4 digitized by the R/D converter 6 is converted to the lower bit 2 from the up/down counter 8.
°~27. Also, the first
The memory 9 and the second memory 10 are composed of nonvolatile memory (bubble memory, EEPROM, etc.) or battery-backed RAM.

In the rotation angle detection device configured as described above, in this embodiment, the motor 3 is provided with a rotation regulating mechanism 13. The rotation regulating mechanism 13 is configured as shown in FIG.

A disc-shaped drum 13a is attached to the drum 13a, and a notch 1 is provided on the outer periphery of the drum 13a.
3b are formed at four locations at 90° intervals. Further, near the outer periphery of the drum 13a, a rod 13c is disposed as a regulating member that fits into the notch 13b and can regulate the rotation of the rotating shaft 3a (that is, the rotating shaft 1a). A spring 13d biases the rod 13c against the outer periphery of the drum 13a when the power is turned off, and a spring 13d biases the rod 13c against the outer circumference of the drum 13a when the power is turned on.
A solenoid 13e is provided to fix and hold the drum c in a state separated from the drum 13a.

In addition, in FIG. 1, the reference numeral 3b is a conventionally provided friction type brake for the motor 3, and the reference numeral 3c is a bearing that pivotally supports the rotating shaft 3a of the motor 3.

Since the rotation angle detection device with a rotation regulating mechanism as an embodiment of the present invention is configured as described above, during normal rotation angle detection, the origin is first aligned, and then the excitation phase (sinωt, A detection button sin (ω is 10) is output from the resolver 4 that receives the signal (cos ωt), and the absolute rotation angle θ within one revolution of the motor 3 is obtained from this detection button, and the detection signal is sent to the R/P converter 7. pulsed by. Then, by counting the pulse signals (A, B phases) with the up/down counter 8, the lower bits 2°~
27 outputs the absolute rotation angle within one rotation, and the upper bits 28 to 215 output the absolute rotation speed of the motor 3 (
The count value) is output, and the absolute rotation angle within one rotation is output.
(absolute rotation speed) x 360°, motor 3
The absolute rotation angle (that is, the absolute rotation angle of the rotating shaft 1a) is detected.

At this time, in the rotation regulating mechanism 13, the solenoid 13
e is in the energized state, and the rod 13a is in the energized state.

Due to electromagnetic force, it is separated from the drum 13a against the biasing force of the spring 13d.

Now, if you turn off the power to the device after the origin has been aligned and the rotation angle has been detected, the detection signal from the resolver 4 at that point will be The lower bits 211 to 27 are stored in the first memory 9 as count values, and the upper bits 21 to 27 from the up/down counter 8 at the same time are stored in the first memory 9 as count values.
2 ts is stored in the second memory 10. At this time,
By turning off the power, the count value in the up/down counter 8 is reset, but the contents stored in the first memory 9 and the second memory 10 are not volatile.

Further, when the power is turned off, the motor 3 is braked by the brake 3b, and in the rotation regulating mechanism 13, the energization to the solenoid 13e is also stopped, and the rod 13c is stopped.
is pressed against the outer peripheral surface of the drum 13a under the biasing force of the spring 13d. After that, even if the arm 1 receives an external force (gravitational moment, etc.) and rotates against the braking force of the brake 3b before the power is turned on again, the rotation will not occur in the notch 13b. Since it is regulated (locked) by fitting the rod 13c, in this embodiment, the rotation angle of the rotating shaft 3a of the motor 3 is 90° at the maximum.
When the notch 13b and the rod 13c are fitted together at the same time as the power is turned off, there is no rotation at all and the rotation is at the minimum of 0°.

When the power is turned off and then turned on again as described above, the detection signal from the resolver 4 is first digitized by the R/D converter 6, and is converted into a digital signal within one rotation when the power is turned on again. The absolute rotation angle is set and input again to the lower bits 2° to 27 of the up/down counter 8, and is also input to the comparator 11. Comparator 1
1, the actual detection signal from the resolver 4 and the detection signal at the time of power off input from the first memory 9 are compared, and a correction command is output to the corrector 12 according to the difference.

Incidentally, even if the arm 1 rotates after the power is turned off, the absolute rotation angle within one rotation will be detected by the resolver 4 after the power is turned on again. (for example, rotate from 10° in the negative direction to 350@, or 350
(When rotating from 10° in the positive direction to 10°)
, one rotation of the motor 3 is not counted, resulting in a detection error.

Therefore, in this embodiment, since the rotation of the motor 3 during the power-off period is restricted to a maximum of 90 degrees by the rotation restriction mechanism 13, the comparison result in the comparator 11 is [(actual detection signal from the resolver 4) - ( If the detection signal from the first memory 9 when the power is turned off)] is between -90'' and +90°, no correction command is output, and when it is between -360' and -2700, the second
A correction command is output to the corrector 12 to add 1 to the count value (upper bits 28 to 215) when the power is turned off from the memory 10, while in the case of 270' to 360', only 1 is added to the count value from the above count value. A correction command is output to the corrector 12 to perform subtraction. In addition, when the comparison result obtained by the comparator 11 is outside the above-mentioned angle range, for safety, an alarm may be output as abnormal value detection.

As a result, even if the motor 3 rotates under external force during the power off period and crosses the zero detection point of the resolver 4,
The number of revolutions of the motor 3 is not miscounted when the power is turned on again, and the comparator 11 and corrector 12 ensure that the count value stored in the second memory 10 at the time of power off includes the rotation during the power off period. After being corrected to the actual count value corresponding to the actual absolute rotation speed, the up/down counter 8
The upper bits 2@~2 is set.

Therefore, even if the motor 3 is rotating during the power off period,
When the power is turned on again, the absolute rotation angle of the motor 3 is calculated from the up/down counter 8 which is the sum of the absolute rotation angle within one rotation from the resolver 4 and (actual count value obtained by correction) x 360'. is detected accurately as the output of

As described above, according to this embodiment, the arm 1 (that is, the motor 3) that occurs between the time the power is turned off and the time the power is turned on again.
The rotation of the frame is reliably regulated within a predetermined angular range (90° in this embodiment) by the rotation regulating mechanism 13 without using a large brake, so the rotation of the bone can be easily corrected when the power is turned on again. This eliminates the need to adjust the origin when the power is turned on again, greatly improving the accuracy of detecting the absolute rotation angle.

In addition, in the rotation regulating mechanism 13 of the above embodiment, the notch portion 1
3b is formed at four locations on the outer periphery of the drum 13a, and the motor 3
Although the rotation of the notch 13b is restricted to a maximum of 90°,
may be formed at two locations at 180° intervals to restrict the rotation of the motor 3 to a maximum of 180°. In this case, when the comparison result in the comparator 11 is between -180° and +180', the correction command is issued. Without outputting, when the value is between -360° and -180°, 1 is added to the count value from the second memory 10 when the power is turned off, while when it is between 180° and 360'', 1 is subtracted from the above count value. to correct.

Further, in the rotation regulating mechanism 13 of the above embodiment, the drum 13
The rotation of the motor 3 is regulated by fitting the rod 13c into the notch 13b on the outer periphery of a. The rotation of the motor 3 may be restricted by bringing them into contact with each other.

Further, as a matter of course, it is desirable that the rotatable angular range by the rotation regulating mechanism 13 is smaller than the angular range used for determination by the comparator 11 (with a margin).

Further, in the above embodiment, the resolver 4 for one rotation is used as the rotation angle detection means, but an absolute encoder for one rotation or an incremental encoder with two pulses may be used.

[Effects of the Invention] As detailed above, according to the rotation angle detection device with a rotation restriction mechanism of the present invention, even if the rotating member rotates due to external force during the power off period, the rotation restriction mechanism prevents the rotating member from rotating at a predetermined level. Since the angle is reliably regulated within the angle range of The detection accuracy is greatly improved, and there is an effect that a complete multi-rotation type absolute rotation angle detection device can be obtained with an extremely inexpensive and simple configuration.

[Brief explanation of drawings]

Figures 1 to 3 show a rotation angle detection device with a rotation restriction mechanism as an embodiment of the present invention. Figure 1 is a longitudinal sectional view showing the rotation restriction mechanism, and Figure 2 is a longitudinal sectional view of the rotation restriction mechanism. The front view and FIG. 3 are block diagrams showing the overall configuration of this device. In the figure, 1-arm as a rotating member, 1a--rotating shaft, 2--reducer, 3-motor, 3a-- rotating shaft, 3b-friction brake, 4--resolver as rotation angle detection means. , 5 - driver, 6 - resolver/digital (R/D) converter, 7 - resolver/pulse (R/P) converter, 8 - up/down counter, 9 - first memory as storage means, 10 - Second memory as storage means, 1
1- Comparator. 12-corrector, 13-rotation regulating mechanism, 13a-drum,
13b-notch portion, 13c-rond as a regulating member;
13d-Spring, 13e-Solenoid. Patent applicant: Kobe Steel, Ltd.

Claims (1)

[Claims] A rotation angle detection means attached to the rotation shaft of the rotation member to detect the absolute rotation angle of the rotation shaft, and a storage means for storing the detection signal from the rotation angle detection means when the power is turned off. A disc-shaped drum is provided, and a plurality of notches or protrusions are provided at equal angular intervals on the outer periphery of the drum, and the rotating shaft is rotated by fitting or abutting on these notches or protrusions. A regulating member capable of regulating the
A rotation angle detecting device with a rotation regulating mechanism, characterized in that a spring is provided that biases the regulating member toward the outer periphery of the drum when the power of the rotation angle detecting device is turned off.