JPS63228308A - Origin returning method for moving object - Google Patents

Abstract

PURPOSE:To automatize all origin returning works by setting an origin detecting area including an overtravel detection position and executing a usual origin returning work after forcedly putting a moving object in the area inner from the origin detecting area when the moving object is in the origin detecting area. CONSTITUTION:As for the overtravel detection position XOT for detecting the overtravel of the moving object, the origin detecting area A having a specified length is set on the inner side including the position XOT and in the case of returning the origin the usual origin returning work is executed after forcedly putting the moving object in the area inner from the origin detecting area A when the moving object is within the origin detecting area A. And when it is in the area inner from the origin detecting area A the usual origin returning work is make to be executed toward the origin. Thus, the origin returning can be completely automatically executed without necessitating the discrimination of direction and the mode switching operation of an operator.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a method for returning a moving body to its origin.

(Prior Art) Incremental encoders are often used for moving objects such as machine tool tables and robots to detect their moving positions.

However, since the incremental encoder is a position detector that detects the current position by applying the integrated value of the relative movement amount using a preset origin position as a reference, it is necessary to tell the origin position before starting work. Must be.

The conventional origin return method is as follows.

First, an overtravel detection switch is provided at one end of the movement area, and a limit switch for setting the origin is provided a predetermined distance away from this switch.

Therefore, the operator sets the mode changeover switch to "manual mode" and moves the movable body inward from the origin setting limit switch.

Here, if the moving object is mistakenly moved to the overtravel switch side, the moving object will actuate the overtravel switch and generate an alarm, so alarm processing is required.

Next, when the movable body is moved inward from the origin setting limit switch, the mode changeover switch is switched to the "origin return mode" and the movable body is moved toward the origin until the origin lamp lights up.

By these operations, the NC device decelerates based on the position detection signal of the limit switch for setting the origin, and sets the origin position using the grid signal of the incremental encoder that appears subsequently.

(Problems to be Solved by the Invention) However, in the conventional method of returning a moving body to the origin as described above, a mode switching operation is required when starting the return to the origin, and if the direction of the movement operation is wrong, There were problems such as generating an alarm.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for returning a movable object to its origin in a fully automatic manner without requiring an operator to determine the direction or to switch modes.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a method for returning a movable body to an origin, which is equipped with an incremental encoder and moves in a movement area with reference to a preset origin. , an origin detection area of a predetermined length is set inside the overtravel detection position including this position for detecting overtravel of the movable body, and when the movable body is in the origin detection area when returning to the origin, the Forcibly enter the area inside the origin detection area and then start the normal return-to-origin operation, and if it is inside the area than the origin detection area, start the normal return-to-origin operation toward the origin. I did it like that.

(Function) In the present invention, an origin detection area of a predetermined length is set inside the overtravel detection position, and it is automatically determined in which direction the mobile body bag should be moved to return to the origin in this area. Let them judge.

When the movable body is within the origin detection area, the moving body is moved inside the origin detection area, and then a normal origin return operation is performed;
If this is not the case, the normal return-to-origin operation is performed.

(Example) Hereinafter, the present invention will be described in detail using an example in which the moving body is a table of a machine tool.

FIGS. 1 and 2 are explanatory diagrams showing the moving state of the table. FIG. 1 shows a state in which the table is sufficiently inside the origin, and FIG. 2 shows a state in which the table is positioned at the origin.

As shown, the table 1 is guided along an axis X by a ball screw 3, and the position on the axis X is detected by an incremental encoder 5.

On the axis is provided. The origin detection area A is set at a predetermined length inside the overtravel detection position XOT, including the overtravel detection position XOT. In order to detect both limit switches 7.9, a dog 11 longer than the length of area A is provided at the lower end of the table. Assuming that the inner end position to the origin detection area is XD, the origin Xo is set a predetermined distance outward from this.

FIG. 3 is a flowchart of the origin return process.

In the origin return process shown in this example, by manually turning on the return switch in step 301, the rest is automatically performed.

In step 302, the operating state of the origin LS9 is determined. Here, the origin LS9 is on, that is, the dog 11 is at the origin L
If S9 is touched (see FIG. 2), it is determined that the table 1 is near the origin Xo, and the process moves to step 303. At this time, since the origin detection area A is set to include the overtravel detection position XOT, the table 1 is always set to the origin X.

It's nearby.

In step 303, considering that table 1 is near the origin Xo, in order to move table 1 inward and then return to the origin, the plus (10) movement flag is turned on and the flag of a timer (not shown) is set. is turned on, the table 1 is moved inward at high speed, and the process moves to steps 304 to 30B.

FIG. 4 shows the subsequent steps 303-308 and 309.
It is an explanatory view showing the operation state of each member in processing of -314. (Note) The figure shows the position and speed of the table 1, the figure (b) shows the operating state of the origin 189, and the figure (C) shows the generation state of the grid signal of the encoder 5. Symbols ■ to ■ indicate the order of operations in Table 1.

In step 304, it is determined whether the origin LS9 is turned off, and in step 305, the time-up of the timer 1 is determined until the origin LS9 is turned off. If the timer 1 times up before the origin LS9 is turned off, it is determined that the origin LS9 is malfunctioning. If so, table 1 is suddenly stopped and an alarm is output.

Here, the setting time of timer 1 is based on table 1 as the origin
The time is set to be slightly longer (for example, 2 seconds) than the necessary and sufficient time to leave area A.

If it is determined in step 304 that the origin LS9 is off (see FIG. 4(b)), the process moves to step 306, where timer 1 is turned off, and then the timer 1 is turned off to ensure sufficient coasting. Turn on 2.

The set time of timer 2 is, for example, 1 second.

In step 307, it is determined whether timer 2 has timed up, and after timer 2 has timed up, the process moves to step 308.

In step 308, timer 2 is turned off and table 1 is
is stopped, and the process moves to step 309.

As described above, through the processing of steps 303 to 308, the table moves in the order of ■, ■, ■ in the fourth icon) and stops inside the origin detection area. At this time, since the failure of the origin LS9 is determined in steps 304 and 305, the table 1 will not run out of control toward the inner area due to a failure of the origin LS9.

In step 309, the minus (-) movement flag is turned on, and the table 1 is moved at high speed toward the origin Xo force direction.

In step 310, it is determined whether the origin LS9 is on, and if the origin LS9 is on, the process moves to step 311.

In step 311, the high-speed movement flag is turned off, and the process proceeds to step 312.

In step 312, the low speed movement flag is turned on and the table is moved at low speed toward the origin Xoh.

In step 313, the grid signal of the encoder 5 is detected, and when the second grid signal G2 appears as shown in FIG. 4(C), the process moves to step 314, where the table 1 is stopped.

As described above, through the processing of steps 309 to 314, table 1 moves in the order ■, ■, ■, ■ shown in FIG. 4 (2),
It is decelerated at the deceleration position XD, stopped at the origin Xo, and returned to the origin.

On the other hand, the home return switch is turned on in step 301.
Next, if it is determined in step 302 that the origin LS9 is off, it is determined that table 1 is currently inside the origin detection area A, and the process directly proceeds to step 309, where the processing up to step 314 is performed. . The processing status of steps 309 to 314 at this time is shown in FIG. 5, and the table operations (1), (2), (2), (2) are the same as the operations (2), (2), (2), (2) shown in FIG.

As described above, by the process shown in FIG. 3, the table 1 is automatically returned to its origin regardless of its current position.

At this time, the maximum escape time for the origin detection area A is set by timer 1, so even if the origin LS9 fails,
Even if it remains on, if this means that area A has not yet escaped, the table 1 will not move out of control toward the inner area prematurely.

In the embodiment shown above, the overtravel position XOT and the origin detection area A are detected by the limit switch 7.9, but the detection of these positions XOT and area MA is performed by other sensors, for example, an optical sensor. Of course, it is also a good thing.

Note that the present invention is not limited to the above-mentioned embodiments, but can be implemented in other embodiments by making appropriate design changes.

[Effects of the Invention] As described above, the present invention sets an origin detection area including an overtravel detection position, and when a moving object is in this area during return to the origin, the moving object is assumed to be near the origin and is moved inside. Since this method of returning to the origin involves moving the robot and then returning to the origin, the entire origin return work can be performed automatically.

[Brief explanation of drawings]

The drawings all show examples, and FIGS. 1 and 2 are explanatory diagrams showing the movement state of the table, FIG. 3 is a flowchart of the origin return process, and FIGS. 4 and 5 are illustrations of each stage during the origin return process. FIG. 3 is an explanatory diagram showing the operating state of the member. 1...Table 3...Ball screw 5...
・Incremental encoder 7...Limit switch for overtravel position detection 9...Limit switch A for origin detection...Origin detection area XO...Deceleration position XOT...Overtravel detection position Xo...Origin Agent Patent Attorney Yasuo MiyoshiFigure 1Figure 2Figure 4Figure 5

Claims (3)

[Claims] (1) In a method for returning to the origin of a moving body that is equipped with an incremental encoder and moves in a movement area with reference to a preset origin, the position is inside the overtravel detection position that detects overtravel of the moving body, including this position. An origin detection area of a predetermined length is set in the origin detection area, and when the moving object is in the origin detection area when returning to the origin, the moving body is forced to enter an area inside the origin detection area before starting the normal origin return operation. A method for returning a movable body to an origin, characterized in that when the moving object is located in an area inside the origin detection area, a normal origin return operation is performed toward the origin. (2) The moving body according to claim 1, wherein the normal return-to-origin work is to decelerate at the inner end of the origin detection area, and then set the origin position by detecting a grid of an incremental encoder that appears. How to return to origin. (3) The return of the movable body to the origin according to claim 1, wherein the forced inward movement is time-limited to a time slightly longer than the time necessary and sufficient to escape the origin detection area. Method.