JPH01248019A - Magnetic encoder - Google Patents

Abstract

PURPOSE:To enable the supplying of a power to an increment/decrement counter constantly regardless of power failure, by providing a magnetic encoder with an induced electromotive force drawing means to taken out an inducted electromotive force generated with the rotary motion of the magnetic encoder as supply power to said counter. CONSTITUTION:A rotary drum 1 is adapted to turn in a direction of the same angle as an angle of joint rotation of a robot arm 4 and angle of rotation information thereof is inputted into an increment/decrement counter 6 from a magnetic sensor 5. In the normal operation, a power from a power source 10 is taken into a backup power source 9 through a charge adjusting circuit 11 and a power from a coil 7 for power generation is done thereinto through a charge adjusting circuit 8 to maintain the function of the increment/decrement counter 6. In case of a power failure, when power stored in a backup power source 9 is about to consume, by external operation of the robot arm 4, the rotary drum 1 is revolved thereby supplying an induced electromotive force taken-in with the coil 7 for power generation through the backup power source 9 to be supplied to the incremental/decremental counter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a magnetic encoder, and more particularly to a magnetic encoder in which a counter is backed up by backup power.

(Prior art) Conventionally, motors used to drive the joints of industrial robots have built-in encoders to detect the rotation angle of the motor, and this controls the joint positions of the robot. , appropriate robot work will be realized.

Generally, encoders use the absolute method (hereinafter referred to as AB
S method) and incremental method (hereinafter IN
Type C). The ABS method is designed to detect the absolute angle of the rotating shaft immediately after power is turned on, and can immediately provide accurate angle information without the need for zero point correction or other adjustments. On the other hand, I
The NC method is a system that detects the difference between the angles before and after rotation, and cannot detect the absolute angle of the rotating shaft immediately after power is turned on, unlike the ABS method.

However, because the AB and S methods have a complicated mechanism for angle detection, they are generally larger than the INC method, and require the use of relatively small motors, such as those used in robot joints. ABS systems tend to be avoided for certain applications. Therefore, the INC system is equipped with an up-down counter that stores the angle information, and in order to prevent the power supplied to this up-down counter from disappearing in the event of a power outage or emergency stop, a back-up power supply is used to It is now in use.

When such a method is used, the zero point correction of the encoder only needs to be performed once at the beginning, and thereafter it becomes possible to detect the absolute angle of the rotation axis immediately after the power is turned on.

However, conventional backup power sources mainly use alkaline batteries and are charged with normal power from the power source, so if the power outage lasts for a long time, all the stored power is consumed, and when the motor is driven. I had to perform zero point correction again. For this reason, a magnetic encoder that consumes relatively little power is often used instead of an optical encoder that consumes a lot of power, but this still does not solve the problem.

(Problems to be Solved by the Invention) As mentioned above, in the past, when the backup power supply was consumed (due to a long power outage, etc.), zero point correction had to be performed again. When used in joints, a preliminary operation that also serves as line zero point correction must be carried out before restarting operation, which greatly affects productivity.

The present invention aims to solve the above problems and provide a magnetic encoder that can always supply power to an up/down counter even during a power outage.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a magnetic encoder with an induced electromotive force capturing means, and extracts the induced electromotive force generated by the rotational movement of the magnetic encoder, The power is supplied to the counter.

(Function) By providing the power generation coil in this way, even if the power of the backup power source is exhausted, power can be supplied to the up-down counter by manually rotating the encoder, for example. Therefore, a magnetic encoder is realized that can always supply power to the up/down counter even during a power outage.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a robot equipped with a magnetic encoder showing an embodiment of the present invention. The rotary drum 1 has its rotation center axis aligned with the center axes of the output shafts of the motor 2 and the reducer 3, and rotates in the same direction by the same angle as the joint rotation angle of the robot arm 4. .

A plurality of permanent magnets are arranged in parallel around the outer periphery of the rotating drum 1 with their N poles and S poles facing the outer periphery alternately. A magnetic sensor 5, which is magnetic transverse means, is attached near the outer periphery of the rotating drum 1 with a slight gap between it and the rotating drum 1 in order to detect changes in the magnetic flux of the permanent magnet. The magnetic flux information of the permanent magnet obtained from the magnetic sensor 5 is inputted as rotation angle information of the rotary drum 1 to an up/down counter 6 which is a storage means.

On the other hand, near the outer periphery of the rotating drum 1, in order to obtain the induced electromotive force generated by the permanent magnet, a power generating coil 7, which is an induced electromotive force capture means, is installed with a small gap between the rotating drum 1 and the rotating drum 1. . The electric power obtained from the power generation coil 7 passes through a charge adjustment circuit 8 including a rectifier circuit and a backflow prevention circuit, and is taken into a backup power source 9 which is an electric power storage means. Furthermore, the power supplied from the power supply 10 is also passed through a charge adjustment circuit 11 including an overcharge prevention circuit and a backflow prevention circuit.
Connect to backup power source 9. The power from the backup power source 9 and the charge adjustment circuit 11 is input to the up/down counter 6, and the up/down counter 6 is activated at all times.

The power obtained by the power generation coil 7 is converted into rotational speed information of the rotating drum 1 by the amplifier 12, and this speed signal and the angle signal of the up/down counter 6 are sent to the CPU (Ce
ntral Processing Unit) 1
3 is input. Inside the CPU 13, the robot arm 4
The optimal drive pattern of the motor 2 related to the control of the motor 2 is centrally managed, and appropriate commands are sent to the motor 2.

In the present invention having the above-described system, the normal time is 1! Power from source 10 passes through charge regulation circuit 11;
The signal is directly input to the up/down counter 6, and the up/down counter 6 is activated. Then, due to a power outage, Migen 1
If the power supply from 0 is stopped, the charging adjustment circuit 11 has a function of storing the power from the power supply 10 in the backup amplifier power supply 9 during normal times, so the up-down counter is activated by the power from the backup power supply 9. 6 starts.

Furthermore, when the electric power stored in the backup power supply 9 via the charge adjustment circuit 11 is about to be exhausted, this time, by rotating the rotary drum 1 by external operation of the robot arm 4, The induced electromotive force can be taken in by the power generation coil 7 and supplied to the up/down counter 6 via the charge adjustment circuit 8 and the bank up power supply 9.

In this way, conventionally, when the stored power from the power source 10 is exhausted, the function of the up/down counter 6 stops, and accurate angle information cannot be obtained unless the robot arm 4 is operated in preliminary operation after the power source 10 is restored. However, in the present invention, by actively applying an external force to the robot arm 4, which tends to be prohibited from applying external force during a power outage, power is stored in the back amplifier power supply 9, and it is possible to The function of the counter 6 can be maintained. Therefore, it is possible to prevent a decrease in work efficiency caused by having the robot perform a preliminary operation or the like.

Furthermore, the power generation coil 7 can be charged even when the power in the backup power supply 9 is still remaining, but it is necessary to avoid charging the power generation coil 7 in a hurry when the power in the backup power supply 9 is almost exhausted. The backup power supply 9 may be provided with emergency signal generation means. In this case, when the voltage of the backup power supply 9 reaches a certain standard or lower, a warning may be issued with light or sound.

Furthermore, since the rotational speed of the rotating drum 1 can be detected at the same time by the power generation coil 7, there is no need to newly install a high-resolution sensor for speed detection. This creates a magnetic encoder with good controllability that can detect both angle and speed.

[Effects of the Invention] As described above, according to the present invention, a magnetic encoder capable of constantly supplying power to the up/down counter even during a power outage or the like is realized.

[Brief explanation of the drawing]

FIG. 1 is a system block diagram of a magnetic encoder showing the present invention. ■... Rotating drum, 5... Magnetic detection means (magnetic sensor), 6... Storage means (up/down counter), 7
...Induced electromotive force capturing means (power generation coil), 9...
Storage means (backup power supply), 10...power supply.

Claims (2)

[Claims] (1) From a rotating drum in which a plurality of permanent magnets are arranged in parallel, and changes in the magnetic flux of the permanent magnets due to the rotation of the rotating drum,
a magnetic detection means for detecting a rotation angle of the rotary drum; a storage means for storing rotation angle information of the rotary drum detected by the magnetic detection means; a power source for supplying electric power to the storage means; power storage means for charging electric power from the power source while the power source is functioning and supplying the charged electric power to the storage means when the power source is not functioning; and induction generated by the permanent magnet by rotation of the rotating drum. A magnetic encoder comprising induced electromotive force capturing means for supplying electromotive force to the storage means. (2) The magnetic encoder according to claim 1, wherein the induced electromotive force capturing means also detects the rotational speed of the rotating drum.