JPH01280207A - Moving body position detection device and origin position return method - Google Patents

Abstract

PURPOSE:To simplify the device and to facilitate a control procedure by enabling an area discrimination sensor to serve as an origin position detection sensor. CONSTITUTION:Whether a body 1 to be detected is in an R or L area about an origin position is detected from whether the output of the origin position detection sensor 6A is on or off at the position when the power source is turned on. When the body 1 to be detected is in the R area, the body 1 to be detected is moved in an L direction and put in the L area temporarily, and then moved in an R direction. When the sensor 6 detects the origin position, its driving is switched to low-speed driving and when an movement quantity detector (not shown in figure) detects a reference signal, the position is regarded as a real origin position and the body 1 to be detected is stopped. Further, when the body 1 to be detected is already in the L area, the body is moved in the R direction and when the output is inverted at the origin position, the driving is switched to the low-speed driving to detect the real origin position, thereby stopping the body 1 to be detected. Thus, an origin area is omitted to facilitate the control procedure and simplify the device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a position detection device for a moving body and a method for returning to an origin position, and is particularly suitable for position detection and origin return for accurately positioning a robot. The present invention relates to an apparatus and method.

[Conventional technology]

In the conventional position detection device and origin position return method for a moving object, as described in JP-A-61-123905, origin position detection and area discrimination are performed using an origin position detection sensor and an area discrimination sensor. was.

A moving body driven by a servo motor having an incremental movement amount detector cannot know the absolute position of the moving body when the power is turned on. Therefore, we set a clear position in advance as the true origin position, match it with the reference signal generator of the movement amount detector, and after turning on the power, first move the moving object to this position, and then move the relative position from the true origin position. Absolute position is detected by detecting with a quantity detector. In the following explanation, this operation of moving to the true origin position will be referred to as a position return operation. Further, the origin position includes a rough origin position detected by an origin position detection sensor and a precise origin position detected from a reference signal of a movement amount detector. The former is called the origin position, and the latter is called the true origin position. Furthermore, in a position detection device for a moving object that includes a movement amount detector, an origin position/limit position detection sensor, and a sensor detected object coupled to the moving object, the device excluding the movement amount detector is a specific position detection device. I will call it.

A conventional position detection device for a moving body and a method for returning to the original position will be explained with reference to FIGS. 9 to 15.

Conventionally, as shown in FIG. 9 or 10, the origin position detection sensor 5 and the limit position detection sensor 3-4 detect the same part of the protrusion shape of the detected object 1.
4.5 has an apparatus configuration in which a region having a step-like level difference at the origin position of the detected object 1 is detected by the region discrimination sensor 6 which is not on the same line with respect to the moving direction.

In this device, when the limit position is reached, the limit position detection sensors 3 and 4 detect the convex portion of the detected object 1 and detect that the limit position has been reached. on the other hand.

The area discrimination sensor 6 and the origin position detection sensor 5 detect whether the detected object 1 is in the right area (L area) with respect to the origin position or the left area t! The direction of movement for quickly reaching the true origin position is determined by determining whether the position is in the A (R region) or the origin region (see FIG. 15).

Examples of the configuration of the sensor 8 used as the position detection sensors 3, 4, 5, and 6 are shown in FIGS. 11 to 13. When the detected object 1 approaches the sensor 8 by a predetermined distance, moves away from it, or passes through it, the output signal level of each sensor is reversed. This characteristic can be used to detect a specific position.

Next, a method for returning to the origin position will be explained with reference to FIGS. 14 and 15. In this method, moving from the L area to the origin area,
The position where the reference signal is first detected is defined as the true origin position. That is, when the origin position detection sensor 5 is not turned on, the output of the area determination sensor 6 is checked to determine whether or not it is in the R area. When it is in the R region, it is caused to pass further from the origin region to the L region side, return from the L region to the origin region, and reach the true origin position. - way, L
When it is in the area or the origin area, it is moved slightly toward the R area and reaches the true origin position.

In addition, conventional robots are
No. 82, JP-A-61-131883.

As described in Japanese Utility Model Application No. 62-138592, a cable member, a stopper group, and a cushion member exposed outside the main body are used to stop an arm or the like that has gone too far past a predetermined position.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, the output signals of both the origin position detection sensor and the area discrimination sensor are used to return the moving body to the origin position, so the device becomes complicated and expensive, and the origin position return operation is also complicated. was there.

In addition, cable members, stopper groups, and cushion members exposed outside the main body were used to stop arms, etc. that went too far past a predetermined position, so whenever they were hit by a moving object such as an arm, However, over a long period of time, the surface will be destroyed little by little and scattered, causing damage to the installation environment 2, such as IC
This method has the drawback of contaminating the environment such as the clean room during the manufacturing process.

Furthermore, there is also the problem that erroneous signals are output due to the incorporation of external noise, resulting in malfunctions.

An object of the present invention is to provide a position detection device for a moving object that can accurately and quickly detect the true origin position with a simple configuration, does not contaminate the environment where the VI is placed, and can reliably prevent malfunctions. and an origin position return method.

[Means to solve the problem]

In order to achieve the above object, the present invention first sets a moving body driven by a servo motor having an incremental movement amount detector that generates a reference signal at a true origin position that is clear in advance to the true origin position. A position detection device for a movable body that detects the absolute position of the movable body based on a relative position from the position, including a limit position detection unit that detects only the movement limit position of the movable body and a vicinity of the true one-point position. A detected object is driven integrally with the movable body and has a step-shaped origin position detecting unit that detects the origin position at the origin position of the detected body. A limit position detection sensor that detects a limit position detection section, and a limit position detection sensor that is arranged at the origin position near the true origin position and that detects whether the origin position detection section of the detected object is at the origin position or in an area on either side of the origin position. The present invention proposes a position detection device for a moving object, which is equipped with an origin position detection sensor that detects the presence of a moving body.

A stopper may be provided in the housing of the position detection device at a position that the limit position detection section of the detected object hits when the limit position detection section of the detected object moves slightly beyond the movement limit position.

The origin position is set to a position separated from the true origin position by a distance that allows the servo motor to decelerate after the origin position detection sensor detects the origin position and accurately reach the true origin position in the shortest time. It is desirable to place

The present invention also provides an incremental movement amount detector that generates a reference signal at a true origin position that is clear in advance, a limit position detection section that detects only at the movement limit position of the moving body, and a limit position detector that detects only at the movement limit position of the moving body, and a position near the true origin position. A detected object is driven integrally with the movable body and has a step-shaped origin position detecting unit that detects the origin position at the origin position of the detected body. A limit position detection sensor that detects a limit position detection section, and a limit position detection sensor that is arranged at the origin position near the true origin position and that detects whether the origin position detection section of the detected object is at the origin position or in an area on either side of the origin position. In the method for returning to the origin position of a movable body using a movable body position detection device that detects the absolute position of the movable body driven by a servo motor, the origin position detection sensor detects whether the movable body is It is determined in which area on either side of the origin position the moving body is located based on a sensor signal, and the movable body is directly moved in the direction of the origin position to reach the origin position, and the moving direction is changed from the origin position. If the direction of movement matches the direction of movement to the true origin position, the moving body is moved in the same direction, and when the movement amount detector generates a reference signal, the moving body is stopped; The present invention proposes a method for returning a movable body to an origin position, in which the movable body is moved in the opposite direction if it is different from the direction of movement to the true origin position, and the movable body is stopped when the movement amount detector generates a reference signal. be.

When detecting the reference signal, a previously stored reference signal pattern is read out multiple times and compared with the detected reference signal multiple times to determine coincidence and eliminate the influence of noise.

[Effect]

In the present invention, since the area discrimination sensor also serves as the origin position detection sensor, the device configuration is simplified and the control method is simplified by reducing the number of steps.

In addition, since the stopper is placed inside the housing,
Even if an arm or the like goes too far over a predetermined position and collides with a stopper, fragments scraped from the stopper will not be scattered and will not pollute the environment such as a clean room.

As an origin position sensor and both limit position sensors.

For example, an optical proximity sensor is used. The output signal of this sensor is inverted when the object approaches or moves away from a predetermined distance. The output signal is a binary signal, but an incorrect signal may be output due to the mixing of external noise, etc. When reading from the central processing unit, the signal level is determined by reading it multiple times and determining the signal level based on the coincidence. By doing so, malfunctions due to erroneous signal reading can be prevented.

During the home position return operation, the current position of the moving body is determined by a program stored in the central processing unit according to the signal level of the sensor, and a speed command is sent to the servo motor drive device.

The servo motor drive device does not malfunction because it is feedback-controlled so that the moving direction and moving speed of the moving body driven by the servo motor match the command value. When the true home position is reached, the speed command becomes 0.
Then, the moving body stops.

〔Example〕

In the conventional example described above, an origin region is provided between the L region and the R region, but the same function can be easily realized even with a structure in which no origin region is provided. below.

Embodiments of a moving body position detection device and an origin position return method made according to the present invention based on this idea are shown in FIGS.
This will be explained using FIG.

FIG. 1 shows a specific position detection device for a rotating moving body. In this embodiment, the origin position detection sensor 5 of the conventional device shown in FIG. 9 is removed, and only the area discrimination sensor 6 is used to perform area discrimination and origin position detection. Although FIG. 1 shows an example in which the limit position detection section of the detected object 1 has a shape in which a convex portion is detected only at the limit position, it may also have a shape in which a concave portion is detected only at the limit position. In the following description, the sensor of the present invention, which is placed at the position of the conventional area discrimination sensor 6 and has both the area discrimination function and the origin position detection function, will be referred to as the origin position detection sensor 6A for convenience.

The method for returning to the origin position will be explained with reference to FIGS. 2 and 3. The zero-point method achieves the same function with fewer steps than the conventional example shown in FIG. 14.

Depending on whether the output of the origin position detection sensor 6A is on or off at the position when the power is turned on, it is detected whether the detected object 1 is currently in the R region or the L region with respect to the origin position.

When the detected object 1 is in the R area, move it in the L direction,
-Let them enter the area. Next, the movement is made in the R direction, and when the origin position detection sensor 6A detects the origin position and reverses the output, the drive is switched to a lower speed, and when the reference signal is detected by the movement amount detector, the position is set to the true position. The detected object 1 is stopped at the origin position.

On the other hand, if it is in the initial region, move in the R direction, and when the output is reversed at the origin position, switch to a slower drive,
Detects the true origin position and stops.

Since the origin region is omitted in this method, the number of steps is three fewer than in the conventional method, the configuration of the device itself is simplified, and the method for returning to the origin position is also simplified.

In addition, when reading out the signals from each sensor, etc., a method is adopted at each step in which the signals are read out multiple times in succession, and when the results match, the position is determined based on the detection results. It is possible to prevent erroneous reading due to noise intrusion and other malfunctions.

Furthermore, when the convex limit position detection part of the detected object 1 goes too far beyond the limit position detection position, it hits the stopper 9, and the movement of a moving object that moves in the same manner as the detected object 1 is forcibly stopped. Ru. Therefore, by using the position detection device of this embodiment, safety can of course be ensured, but since the stopper 9 is sealed within the housing of the device, the stopper 9 may cause frequent collisions. Even if the device is damaged little by little, the fragments will not come out and will not contaminate the environment in which it is installed, such as a clean room.

FIG. 4 shows an example of an internal cylinder rotor type direct drive motor (D-D motor) incorporating the specific position detection device of FIG. 1. In the figure, 10 is a DD motor rotor, 11 is a DD motor stator, and 12 is a movement amount detector. Here, an example is shown in which a brushless resolver is used as the movement amount detector 12, but an optical encoder,
A ground displacement detector such as a magnetic encoder may also be employed.

By attaching the position detection device directly to the hollow type D-D motor in this way, other wiring can be passed through the hollow hole, and there are no protruding parts such as stoppers exposed to the outside, so dust generation to the outside is prevented. The amount can be significantly reduced, making it suitable for use in clean rooms, etc.

FIG. 5 shows an example of a horizontal articulated D/D robot using the D/D motor shown in FIG. 4. This robot has a first arm 14 attached to the rotor of a single-axis drive DD motor 13.
and a two-axis drive D-D provided at the tip of the first arm 14.
It consists of a second arm 16 attached to the rotor of the motor 15, and a wrist support N17 provided at the tip of the second arm 16 to enable vertical and rotational movement of the spline shaft 18.

The wrist device 17 rotates the vertical axis motor]9.

A spline shaft is transmitted through a pulley and timing belt to the ball screw shaft 20 to generate vertical movement of the ball screw nut, and is restrained in the vertical direction by the bracket 24 via the ball screw nut and the bracket 24. 1
8 vertical movements. Further, the rotation of the wrist rotating shaft drive motor 21 is decelerated by a reducer 22, and the rotation of the wrist rotating shaft drive motor 21 is
A timing belt transmits the signal to a pulley connected to a spline bearing. The spline bearing transmits its rotational force to the spline shaft 18, causing it to rotate.

Next, the basic configuration of the specific position detection device for a linearly moving object is explained in the sixth section.
As shown in the figure. The detected object 1 is formed into an L-shaped convex shape. In the figure, the upper convex portion is a detected portion for limit position detection, and the lower portion is a detected portion that serves both area discrimination and origin position detection. Effective length of detected part for area discrimination (distance M excluding sensor diameter)
If the length of Q is longer than the distance Q2 between the origin position detection sensor 6A and the left limit position detection sensor 3 (Q1≧L
), the origin position detection sensor 6A is always covered when the area discrimination part of the detected object is to the left of the installation position of the sensor 6A, and is always uncovered when it is to the right of the installation position of the sensor 6A, so that area discrimination is possible. Become. In addition, the origin position can be detected based on whether the edge is covered or not.

If the reference signal generation position (true origin position) of the movement amount detector is set slightly to the right of the origin position, the true origin position will be accurately reached using the algorithm shown in Figure 2, similar to the rotary type. can. Regarding the arrangement of the true origin position, of course, the right and left positions can be reversed, and they can also be replaced in the vertical direction.

FIG. 7 shows an embodiment in which the basic configuration of FIG. 6 is applied to the specific position detection device for the ball screw shaft 20 of the embodiment of FIG. 5. FIG. 7 is a cross-sectional view taken along the line ■-■ in FIG. 5. A ball screw shaft 20 is provided between a fixed plate 30 and a mounting plate 31, which are sandwiched between plate members 28 and 29, via a bearing. The ball screw nut portion 23 is coupled to a bracket 24, and the detected object 1 is attached to the #1 surface of the bracket 24. On the other hand, the origin position detection sensor 6A is attached to the sensor mounting plate 32 fixed to the plate member 28 at a position away from the straight line connecting the limit position detection sensors 3 and 4. The dimensions are adjusted so as to satisfy the relationship Qt≧Q3 between the origin position detection of the detected object 1 and the illustrated effective detection ratio @nt of the area discriminator and the lower limit area effective distance Q3 from the origin position to the lower limit position. Once determined, area discrimination and origin detection can be performed without malfunction. Furthermore, if the stoppers 9a and 9b are provided on the sensor mounting plate 32 at the positions indicated by two-dot chain lines, if the detected object 1 goes too far beyond the operating range, the limit position detection section of the detected object 1 will be moved to the stop 9a. Or it hits 9b and stops the movement.

In addition, in this vertical movement mechanism system, the ball screw nut 23
It is also possible to provide stoppers 9a and 9b on the lower surface of the fixed plate 30 and the upper surface of the mounting plate 31, respectively, to stop the operation.

In the case of a wrist vertical axis drive device that includes a movement detection device for a linear moving body, the number of sensors can be reduced compared to the conventional example shown in FIG. Can be secured.

Furthermore, the number of steps in the home position return method is also reduced.

Next, a specific position detection device for the wrist rotation axis of the DD robot shown in FIG. 5 will be explained with reference to FIG. 8. The power of the rotary shaft motor 21 reduced by the speed reducer 22 is transmitted to the pulley 27 via the pulley timing belt. Since the pulley 27 is restrained in one rotation direction with respect to the spline shaft 18, when the object 1 to be detected is attached to the pulley 27, the operating range is 36.
If the angle is less than 0 degrees, position detection becomes possible as in the example in FIG.

Both the position detection device and the home position return method are simplified.

〔Effect of the invention〕

According to the present invention, the origin position detection, limit position detection, and area discrimination of a moving body having an incremental type movement amount detector can be realized with a minimum number of sensors, and the origin position return operation can be performed quickly with fewer steps than before. Since it can be executed, it is possible to shorten the initial setting time of a moving body such as a robot arm, reduce costs, and increase work efficiency.

In addition, in any of the examples of the present invention, a stopper that is used when the limit position detection section operates beyond a predetermined position is sealed in the device housing, so even if the stopper is scraped due to repeated collisions, the stopper is sealed. , its fragments will not scatter and contaminate the installation environment such as a clean room.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a specific position detection device according to the present invention for a rotating moving body, FIG. 2 is a flowchart of a method for returning the device shown in FIG. 4 is a vertical sectional view of the DD motor equipped with the specific position detection device shown in FIG. 1, and FIG. 5 is a vertical sectional view of the DD robot equipped with the specific position detection device according to the present invention.
Fig. 6 is a diagram showing a specific position detection device for a moving body that moves laterally, Fig. 7 is a longitudinal cross-sectional view of a specific position detection device in which the device in Fig. 6 is applied to the wrist vertical axis, and Fig. 8 is a diagram showing the robot shown in Fig. 5. FIG. 9 is a longitudinal cross-sectional view of a specific position detection device for a wrist rotation axis; FIG.
Figure 0 is a diagram showing a conventional specific position detection device for a moving body moving in a straight line, Figures 11 to 13 are diagrams showing examples of position detection sensors, and Figure 14 is a flowchart showing a conventional home position return method. , FIG. 15 is a diagram showing the relationship between each area in the conventional example. DESCRIPTION OF SYMBOLS 1... Object to be detected, 2... Fixed body, 3, 4... Limit position detection sensor, 5... Origin position detection sensor, 6...
- Area discrimination sensor, 6A... Origin position detection sensor of the present invention, 7... Moving direction of detected object, 8... Position detection sensor, 9... Stopper, 10... D-D motor・
Rotor, 11...D-D motor stator, 12...
・Movement amount detector, 13...1-axis D-D motor, 14・
...First arm, 15...2-axis D-D motor. 16... Second arm, 17... Wrist device, 18...
・Spline shaft, 19...Wrist vertical axis motor, 20・
...Ball screw shaft, 21...Wrist rotation motor, 22.
...Reducer, 23...Ball screw nut part, 24...
- Blanket, 25... Pulley, 26... Spline bearing, 27... Pulley, 28, 29... Plate member. 30...Fixing plate, 31...Mounting plate, 32...Sensor mounting plate, 33...Spline bearing mounting member.

Claims (1)

[Claims] 1. A movable body driven by a servo motor having an incremental movement amount detector that generates a reference signal at a predetermined true origin position is first moved to the true origin position. A position detection device for a moving body that detects the absolute position of the moving body based on a relative position from the moving body, comprising: a limit position detection unit that detects only the movement limit position of the moving body; and a limit position detection unit that detects only the movement limit position of the moving body; a detected object that is driven integrally with the movable body and has a step-like origin position detecting section; a limit position detection sensor for detecting; and a detection unit arranged at the origin position near the true origin position to detect whether the origin position detection section of the detected object is at the origin position or in which region on both sides of the origin position. 1. A position detection device for a moving body, comprising an origin position detection sensor. 2. The position detection device for a moving object according to claim 1, wherein when the limit position detection portion of the detected object moves slightly beyond the movement limit position within the position detection device housing, the limit position detection portion A position detection device for a moving object, characterized in that a stopper is provided at a contact position. 3. The moving body position detection device according to claim 1 or 2, wherein the servo motor decelerates after the origin position detection sensor detects the origin position so that the true origin position can be accurately reached in the shortest possible time. A position detection device for a moving body, characterized in that the origin position is located at a position separated from the true origin position by a distance. 4. An incremental movement amount detector that generates a reference signal at a true origin position that is clear in advance, a limit position detection unit that detects only the movement limit position of the moving body, and an origin position near the true origin position. a detected object that is driven integrally with the movable body, and a step-like origin position detecting unit that detects the position of the detected body; a limit position detection sensor that detects the origin position, and an origin position detection part of the detected object that is arranged at the origin position near the true origin position and detects whether the origin position detection part is at the origin position or in which region on both sides of the origin position. A method for returning a moving object to an origin position using a moving object position detection device that detects an absolute position of the moving object driven by a servo motor, comprising: an origin position detection sensor that detects an absolute position of the moving object driven by a servo motor; determine in which region on either side of the origin position the moving body is located, and directly move the movable body in the direction of the origin position to reach the origin position, and the moving direction changes from the origin position to the true If it matches the direction of movement to the origin position, move it in the same direction,
When the movement amount detector generates a reference signal, the moving body is stopped, and when the movement direction is different from the movement direction from the origin position to the true origin position, the moving body is moved in the opposite direction, and the movement is stopped. A method for returning a movable body to an origin position, comprising: stopping the movable body when a quantity detector generates a reference signal. 5. The method for returning a moving object to an origin position according to claim 4, wherein when detecting the reference signal, a previously stored reference signal pattern is read out multiple times and compared with the detected reference signal multiple times to determine a match. A method for returning a moving body to an origin position, characterized in that: