JPH011910A - Rotation angle detection device for industrial robots - 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 [Industrial Application Field] The present invention relates to a rotation angle detection device for detecting the absolute rotation angle of each rotating shaft in an industrial robot or the like.

[Prior Art] Generally, when controlling an industrial robot, etc., a detection device that detects the rotation angle of each rotation axis of the arm etc. with high precision is required, and as such a rotation angle detection device, Incremental sensors with a simpler structure and lower cost than absolute detection devices, which are complex and therefore expensive.
type detection devices are commonly used.

As this rotation angle detection device, there is conventionally one shown in FIGS. 3 and 4. In Figures 3 and 4, 1 is an arm of an industrial robot, 2 is a motor that rotationally drives arm 1 via a reducer (not shown), and 3 is a pulse encoder (P
E), this "pulse encoder 3" is connected to the rotating shaft of the motor 2, and as shown in FIG. 5, as the motor 2 (arm 1) rotates, the pulse encoder 3 Outputs a Z pulse signal for setting the origin or detecting the number of rotations for each rotation, and also outputs a Z pulse signal for detecting the rotation angle.

It outputs a B/<rus signal. Here, A.

The B pulse signals are output with a phase difference of 90', and the direction of rotation can be detected by looking at the relationship between these A and B pulse signals.

Further, 4 is a striker fixed to the arm 1, and 5 is arranged on the fixed side and is turned ON by the striker 4.

A limit switch for detecting that the arm 1 is in the original position after being turned off; 6 is an up/down counter that counts the number of A and B pulse signals from the pulse encoder 3 and outputs the count value as a rotation angle; 7 is a zero signal generator. This zero signal generator 7 is for receiving the Z pulse signal from the pulse encoder 3 in response to ON/OFF signals from the limit switch 5 and setting the origin of the up/down counter 6.

Further, reference numeral 8 denotes a main control device that drives and controls the arm 1 by using the count value from the up/down counter 6 as the rotation angle of the arm 1.

With the above configuration, when detecting the rotation angle, when the arm 1 starts moving from its original position, as shown in FIG.
Pulse encoder 3 to Z, A.

As the B pulse signal begins to be output, the striker 4 contacts the limit switch 5 and turns from OFF to ON. After this limit switch 5 is turned ON, the zero signal generator 7 starts the up/down counter 6 at that point so that the point when the Z pulse signal is first input to the zero signal generator 7 is set as the origin. A reset clear signal is output and home alignment is performed.

Thereafter, in the up/down counter 6, while determining the rotation direction based on the A and B pulse signals input from the pulse encoder 3, A and B are determined depending on whether the rotation direction is forward or reverse.
Count up or down the pulse signal.

In this way, the count value (16 bits is shown in FIG. 4) counted by the up/down counter 6 is output as the rotation angle to be detected.

[Problems to be Solved by the Invention] By the way, when starting one rotation angle detection, limit switch 5. It is necessary to perform origin alignment using the Z pulse signal from the zero signal generator 7 and pulse encoder 3. - Once the origin is aligned, the output of the up-down counter 6 can be used as an absolute signal (absolute rotation angle) as long as the counter value in the up-down counter 6 does not disappear.

However, in the conventional rotation angle detection device described above, when the power supply 8 that supplies power to the up/down counter 6 is cut off from the counter 6, the counter value disappears. For example, this is the case when the robot learns of an abnormality and puts it into an emergency stop state at the end of the day's work. Power 8 again
When the rotation angle is turned on, the absolute rotation angle from the origin position cannot be detected unless the above-mentioned origin alignment is performed again.

When performing home alignment work, the robot must make complicated movements in order to return arm 1 to the home position in a narrow space with various devices located nearby, which may cause damage to the robot or peripheral equipment. High risk.

The present invention aims to solve these problems, and uses a conventional low-cost, simple-structured incremental type detector as the rotation speed and rotation direction detection function.
An absolute detector is used to detect the absolute rotation angle within a predetermined rotation angle, and the rotation angle detection device for an industrial robot is equipped with an auxiliary power supply to back up the incremental detector itself and a counter that counts its output signal. The purpose is to provide

[Means for Solving the Problems] Therefore, the rotation angle detection device for an industrial robot according to the present invention includes an absolute angle detector that detects an absolute rotation angle within a predetermined rotation angle (such as one rotation or half a rotation). Predetermined rotation angle (1 rotation)
A pulse detector (incremental type detector) that outputs a pulse signal every time is installed on the rotating shaft of a rotating member, and a conversion circuit that receives the signals of each detector and outputs the detected value in bits. The power supply to the detector paired with the circuit is provided at each stage, and an auxiliary power supply is provided to the power supply to the pulse detector and its conversion circuit.

[Function] In the above-mentioned rotation angle detection device for an industrial robot of the present invention,
Angle within a predetermined rotation angle of the rotating member is detected as an absolute value by an absolute rotation angle detector when the power supply is turned on again, while a pulse signal obtained by a pulse detector for each predetermined rotation angle is detected as an absolute value when the power supply is turned on again. The number of revolutions is obtained by a counting conversion circuit.

Therefore, by providing an auxiliary power supply to the above-mentioned pulse detector and its conversion circuit (pulse counter),
The absolute rotation angle of the rotating member is always detected.

[Embodiment of the Invention] A rotation angle detection device as an embodiment of the present invention will be explained with reference to the following drawings. Fig. 1 is a block diagram thereof, and in Fig. 1, numeral 1 indicates an industrial robot as a rotating member. 2 is a motor (not shown) that rotationally drives the arm 1 via a reducer, and 9 is connected to the rotating shaft of the arm 1 via the motor 2 to detect the absolute rotation angle within a predetermined rotation angle. This is a resolver as an absolute angle detector. The resolver 9 includes a two-pole type that can detect absolute rotation angles within one rotation of the rotation axis (360") and a four-pole type that can detect absolute rotation angles within one half rotation of the rotation axis (180 degrees). However, in this embodiment, the predetermined rotation angle is set to 36
A two-pole type resolver with 0° is used.

Further, 10 is a converter as a conversion circuit that converts the detection signal from the resolver 9 into a binary absolute rotation angle signal and outputs it as a lower bit (10 bits from 2° to 2s).

On the other hand, 11 is a pulse encoder as a pulse detector that outputs A and B pulse signals every rotation of the rotation axis as the arm 1 rotates.The A and B pulse signals are as shown in FIG. The direction of rotation of the rotating shaft can be detected by looking at the sequential relationship between these A and B pulse signals. As the pulse encoder 11, there is used one in which a disk having a slit is attached to one rotation axis and the slit is detected by a photocoupler, or one in which a magnetized drum is detected by a Hall element or the like.

And 12 is A from the pulse encoder 11.

This is an up/down counter as a conversion circuit that counts the number of B pulse signals, and outputs the absolute rotation angle signal corresponding to the rotation angle based on the count value, that is, a multiple of 360°, as the upper bits (6 bits from 210 to 215). It is something to do.

Further, reference numeral 13 designates a backup power source as an auxiliary power source for supplying power to the pulse encoder 11 and up/down counter 12.

Since the rotation angle detection device as an embodiment of the present invention is configured as described above, when detecting the rotation angle of the arm 1, the rotation angle within 360° is always determined as absolute by the resolver 9. is detected, converted into a binary number by the converter 10, and output as lower bits (10 bits). This resolver 9 will retain 36% even when the power is turned off and then turned on again.
For rotation angles within 0@, the correct (absolute) rotation angle is detected.

In addition, in the up/down counter 12, while determining the rotation direction based on the A and B pulse signals output from the pulse encoder 11, A and B are determined depending on whether the rotation direction is forward or reverse.
The number of rotations of the rotating shaft of the motor 2 connected to the arm 1 is detected by counting up or down the B pulse signal, and the count value is stored as the upper bit (6 output in bits).

Then, from the lower bit output from the converter 10 and the upper bit output from the up/down counter 12, arm 1
The absolute rotation angle is obtained.

Furthermore, in this embodiment, since the counter value in the up/down counter 12 is an incremental method and disappears when the power supply is stopped, the pulse encoder 11 outputs only the upper bits (6 bits).
By constantly supplying power from the backup power source 13 to the up/down counter 12, the absolute rotation angle can be detected at all times.

As described above, according to this embodiment, the absolute rotation angle is always detected by the resolver 9 for angle detection within one rotation, and the pulse encoder 11 and the up Since the down counter 12 is used for incremental and mental detection, and the pulse encoder 1 and the up/down counter 12 are backed up by the backup power supply 13, rotation angle detection is performed only by the incremental method. In contrast to conventional equipment, which requires constant power supply to a 16-bit counter, the minimum required 6-bit counter is
Since it is only necessary to supply power to the bit up counter 12 and pulse encoder 11, the power consumption required for backup can be extremely reduced, and backup can be performed for a long time, greatly increasing the reliability of the rotation angle detection device. It improves.

Note that when the resolver shown in the above embodiment is used as a rotation angle detector, it is necessary not only to back up the counter that counts the number of rotations, but also to back up the R-P converter (resolver).
Pulse conversion) must also be backed up, and the power consumption required for these is too large, but by combining the unique features of each incremental type detector, the rotation angle detection data of the rotating member required for backup can be It can be stored and used as an absolute rotation angle detection device.

[Effects of the Invention] As detailed above, according to the rotation angle detection device for an industrial robot of the present invention, desired data can be obtained when the power supply is turned off by combining each unique point in the incremental type detector. It can be used as an absolute rotation angle detection device by backing up only the part that disappears, and the incremental detector that backs up is a pulse detector (pulse encoder), which can store data for a long time, making it an absolute rotation angle detection device. The reliability of the system is greatly improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a rotation angle detection device for an industrial robot as an embodiment of the present invention, and FIG. 2 is a waveform diagram showing a pulse signal output from the pulse detector of the above embodiment.
Figures 3 to 5 show conventional rotation angle detection devices.
4 is a block diagram thereof, and FIG. 5 is a timing chart for explaining the pulse signal output from the pulse encoder and the origin setting means. In the figure, 1 - arm as a rotating member, 2 - motor, 9 - resolver as an absolute angle detector, 1 o - converter as a conversion circuit, 11 - pulse encoder as a pulse detector, 12 - conversion Up-down counter as a circuit, 13-backup power supply as auxiliary supply power supply. Patent applicant: Kobe Steel, Ltd.

Claims (1)

[Claims] An absolute angle detector that detects an absolute rotation angle within a predetermined rotation angle and a pulse detector that outputs a pulse signal at every predetermined rotation angle are installed on the rotating shaft of the rotating member, and the signals from each detector are received and detected. There is a conversion circuit that outputs a value in bits, and a power supply is provided for each of the detectors paired with the conversion circuit, and an auxiliary power supply is provided for the power supply of the pulse detector and the conversion circuit. Features: Rotation angle detection device for industrial robots.