JPS63269016A - Origin detection circuit - Google Patents

Abstract

PURPOSE:To reduce the number of connectors and cables by dispersing with an origin detection sensor, by forming an origin detection signal in synchronous relation to the pulse generate when an encoder after generating an endpoint signal when an object to be moved is present at an endpoint position rotates by predetermined quantity. CONSTITUTION:Endpoint limit detection sensors 1, 6 are respectively provided at the endpoints P, Q of a range where an object to be moved moves. When the moving object to be moved reaches the endpoint P, an endpoint detection signal E is outputted from the sensor 1 and, subsequently, when the object to be moved moves in a reverse direction and the first pulse Z is outputted from an encoder 2 outputting the pulse Z at every one rotation, an origin detection circuit 3 forms and outputs the origin detection signal synchronous to the first pulse Z. By this constitution, the absolute position of the origin can be detected with good accuracy without using an origin detection sensor and the mount number of the sensors are reduced and the number of connectors or cables can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field The present invention relates to an improvement of an origin detection circuit in a position control system using a pulse motor or the like.

Moving bodies are often used in many automatic control devices, robots, etc. Some moving objects, such as a robot's arm, rotate around a certain axis. Alternatively, there are some that move back and forth on a straight track.

Various exercises are possible.

In any movement, a displacement X1θ, a velocity expression, δ, and an acceleration x1θ are defined.

Regarding displacement, the direction of displacement is determined using a fixed point as a reference. Displacement is given by the length along that direction from the reference point.

In this case, the reference point must be determined accurately. The reference point is called the origin. This is the position where X=O.

The direction of displacement may be in a straight line or in a circular arc. The direction is arbitrary. There is also a range in which it can be displaced.

This is also called a stroke. It can be called the operating range. Let PQ be the operating range. Origin 0 can be set at any point in PQ.

The animal moves through its range of motion. The animal can be moved freely in the positive and negative directions using a pulse motor or the like.

The number of pulses applied to the pulse motor is proportional to the displacement position.

The movement of the animal can be detected by an encoder that follows the rotation of the animal's wheels or the like.

The encoder mechanically or optically captures the movement of the animal. The count value of the encoder increases or decreases as the animal moves within a certain range.

In order to accurately determine the position of the animal, the origin O must be determined accurately.

It is necessary that the value of the counter becomes 0 at the origin O, and that the position of the animal is accurately determined.

Once you reset the count value to 0 at the origin 0,
From then on, the location of the animal can be accurately determined.

Even if some kind of error occurs and the count value goes out of order, it will be reset when it returns to the origin O, so the error will be corrected immediately.

(b) Conventional technology The prior art will be explained with reference to FIG.

Here, the line segment PQ indicates the movement range of the animal. End point limit detection sensors 1.6 are provided at the starting end P and the ending end Q.

When the animal is at the starting point P, it can be detected by the end point limit detection sensor 1. When the animal is at terminal Q,
This can be detected by the end point limit detection sensor 6.

Further, the movement of the animal can be detected by an encoder 2 that is linked to the movement of the animal.

The operating range PQ may be a straight line or an arc.

In addition to the end point limit detection sensor 1.6, the origin detection sensor 7
will be provided. When the animal is at the origin, the origin detection sensor 7 produces a signal.

Encoder 2 outputs one Z pulse for each rotation.

The product of the Z pulse and the signal from the origin detection sensor 7 is calculated by an AND gate 19, and this is set as the origin signal 5.

The origin O is determined in this way.

(■ Problems to be Solved by the Invention) The conventional origin detection circuit has a separate origin detection sensor 7, so it has the advantage of being able to set the origin at any position.

However, in addition to the two end point limit detection sensors, an origin detection circuit is provided. Three sensors are used to detect the position.

Too many sensors. There may not be enough space to install the sensor. Even if there is a place for installation, the disadvantage of increasing the number of cables cannot be avoided.

Furthermore, the number of connectors becomes too large. Installation work such as soldering also increases the number of man-hours.

c. Purpose It is an object of the present invention to provide an origin detection circuit with a reduced number of sensors, connectors, and cables.

) configuration In the present invention, the origin detection sensor 7 is not used.

Use one of the end point limit detection sensors.

After the end point limit detection sensor emits the end point signal E representing the end point, the origin 0 is detected by the Z pulse generated when the encoder rotates once in the opposite direction.

This will be explained with reference to FIG.

PQ is the operating range, and end point limit detection sensors 1.
6 is provided. When the animal is at an end point, an end point signal E is output.

Proceed in the opposite direction from the end point. Encoder 2 produces one Z pulse per revolution.

So, after reaching the end point, it rotates in the opposite direction and the first two
When a pulse occurs, the origin detection circuit 3 outputs the origin detection signal 3.
4 will now occur.

FIG. 4 shows the Z pulse.

Therefore, the origin 0 is separated from the end point P by only one rotation e of the encoder.

δP = e (1) It is.

A pulse motor or the like is used to move the animal. PID control is often performed using a DC servo motor. F
There is also a case of D control. In any case, the animal can freely move within the motion range PQ.

The encoder 2 is mechanically connected to the axle of the animal, and can detect the distance traveled by the animal by generating pulses every fixed distance.

This kind of thing is publicly known.

The encoder 2 can be of various types. There are mechanical ones and optical ones. In any case, a large number of pulses are generated during one rotation.

If N pulses are generated, the distance measurement accuracy by the encoder 2 is e/'N.

Here, the Z pulse is a pulse that is generated for each rotation of the encoder 2. It is different from other count pulses.

The reason why one Z pulse is counted is as follows.

The end point limit detection sensor 1.6 includes, for example, a limit switch and a contact for turning the limit switch on and off.

The limit switch turns on and off as the animal moves. Of course, it is better to turn it on and off at the same point. However, this is not necessarily the case, the number 10 before and after
There may be a deviation of one or several 0 μm. Values that include such deviations must not be used as reference points.

On the other hand, the pulses of the encoder are generated in exact correspondence with the position of the subject. This is because the encoder axis and the animal axis are mechanically coupled.

Encoder pulses have high positional accuracy, but even Z pulses generate one pulse per rotation, so absolute position cannot be determined from pulses alone.

Therefore, in the present invention, the absolute position of the end point P is known by the end point limit detection sensor 1, and the absolute position of the end point P is detected in the opposite direction of the encoder.
The position is specified with high precision using rotations.

Even if there is an error in the position P of the end point determined by the end point limit detection sensor 1, the error is small in the position where the Z pulse is generated when the encoder is rotated once in the opposite direction. There is only the error of the encoder.

(b) Examples FIG. 2 shows an example of the origin detection circuit.

There is a movement range PQ of the animal. In this environment, the animal can move freely. End point limit detection sensors 1.6 are provided at the end points P and Q.

The animal is provided with an encoder 2, which measures the displacement X of the animal within PQ.

The origin detection circuit includes a D flip-flop 31, an AND gate 32, a delay circuit 33, and the like.

The encoder 2 rotates based on the movement of the animal. Generates N count pulses per revolution. One Z pulse is generated per revolution.

The end point limit detection sensor 1.6 generates a reverse limit detection signal (g) 11 when the animal comes here.

The reverse limit detection signal 11 is output from the D flip-flop 31.
into the preset input PR. D input is power level
Set it to “H”.

The Z pulse signal line 21 of the encoder 2 and the Q output of the D flip-flop 31 are input to an AND gate 32.

The delay circuit 33 is a CR delay circuit using a capacitor C1 and a resistor R. After the voltage of the Z pulse signal line 21 becomes "H" and an origin detection signal is generated, the D flip-flop is cleared after CR. Therefore, the connection point of R and C is the clear terminal CL of the D flip 70 knob 31.
Connected to R.

The origin search operation will be described.

Move the animal to end point P. The end point limit detection sensor 1 detects the end point signal E (in this case, the reverse rotation limit detection signal 1
1) occurs.

As a result, the D flip-flop 31 is set.

Q output becomes "H". Since the encoder 2 does not generate a Z pulse, the output of the AND gate 32 is "L".

Then move the animal in the opposite direction. Encoder 2 rotates in reverse. One Z pulse is generated during the first revolution.

Since both of the two inputs of the AND gate 32 become "H", an origin detection signal is generated at the output. The position where the animal is present at this time is defined as the origin 0. Reset the counter value to a predetermined value.

At this moment, the clear terminal CLR is at "L" level. However, after the time constant CR (Z narrower than the pulse width of the pulse)
Since the level of clear terminal CLH becomes “H”, D
The flip-flop is cleared.

The Q output returns to "L'. From then on, even if a Z pulse is generated, Q = L.
Therefore, the output of the controller 32 does not become H''.

In other words, the origin detection signal is generated only once at a point corresponding to one rotation of the encoder from the end point P. It does not occur at points where there are more than two revolutions.

(→Effect (1) The origin detection sensor can be omitted. This is because the origin is set using the end point limit detection sensor and the Z pulse of the encoder.

(11) Since the number of sensors installed is reduced, the number of cables is reduced. The number of cables and connectors is also reduced.

Installation man-hours such as soldering can also be reduced.

(1) It is ideal as an origin detection sensor for automatic control equipment, robots, etc., especially for equipment with a large number of axes.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an origin detection circuit according to the present invention. FIG. 2 is an origin detection circuit diagram according to the embodiment. FIG. 3 is a diagram of an origin detection circuit according to a conventional example. FIG. 4 is a Z pulse waveform diagram of the encoder. 1......End point limit detection sensor 2
・・・・・・・・・・・・Encoder 3・・・・・・・
・・・・・・Origin detection circuit 6・・・・・・・・・End point limit detection sensor 7・・・・・・・・・Origin detection sensor 11・・・・・・・・・・・・......Reverse limit detection signal 21...Z pulse signal line 31...D flip-flop 32
・・・・・・・・・・・・And Gate 33・・・・・・
・・・・・・Delay circuit 34・・・・・・・・・・・・
Origin detection signal inventor: Kimi Sumi

Claims (1)

[Claims] A circuit for detecting the origin 0 of the displacement The origin detection circuit is characterized in that it generates an origin detection signal in synchronization with a Z pulse generated when an encoder 2 rotates once in the opposite direction after the encoder 2 generates an end point signal E indicating that an animal is present at an end point P.