JPH0634950Y2 - Robot controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a control device for causing a robot to grip a work.

[Conventional technology]

When a work is placed on a conveyor that is moving at a constant speed and is being transferred, the work may be held by the robot.

FIG. 6 shows an overall view of a device for performing such work. In the figure, (1) is a robot, (1a) is an arm,
(1b) is a hand attached to the end of the arm (1a) and has a gripping mechanism for grasping an object. (2) is a controller of the robot (1), which is operated by a command signal from the operation panel (2a). (3) is a belt conveyor, which is composed of an endless belt (3a) wound around a pair of rollers (3b) provided at a predetermined interval. (4) is a work to be transferred placed on the belt conveyor (3),
(5) is a photoelectric device installed at a predetermined position to detect the work (4).

FIGS. 7 and 8 show a conventional control device for holding the work (4) in the robot (1) in the above-mentioned configuration.
It will be described based on the figure.

First, assume that the belt conveyor (3a) is moving in the direction of the arrow in FIG. The photoelectric device (5) detects the work (4) at point P ₁ . The hand (1b) waits at P ₂ point, which is a distance S ahead of P ₁ point.

Here, the distance S is the distance required for the hand (1b) to reach the speed of the conveyor (3a) from the stopped state as shown in FIG.

That is, when the photoelectric device (5) detects the work (4) at time t ₀ while the hand (1b) is waiting at the point P ₂ , the hand accelerates at a predetermined acceleration and the distance is increased. When moving by S, it becomes the same speed as the conveyor (3a). After that, it keeps this speed and moves in synchronization with the conveyor (3a). That is, a hand (1b) in the P ₃ points after, a state capable of holding a workpiece (4).

[Problems to be solved by the invention]

In the conventional robot controller, it is necessary to set the standby position of the hand ahead of the detection point of the work (4) by the distance S in the traveling direction. This distance S changes depending on the speed of the belt conveyor (3a).

Therefore, it is necessary to set the distance S according to the speed of each belt conveyor.

Further, when the speed is changed for adjusting the belt conveyor, even if the belt conveyor itself is the same, the workpiece cannot be gripped unless the distance S is changed due to the change in speed.

Therefore, it was extremely troublesome.

The present invention has been made to solve the above problems, and an object thereof is to make it possible to grip a workpiece without changing the standby position of the hand even if the speed of the belt conveyor changes. .

[Means for solving problems]

The robot controller according to the present invention accelerates a hand from a fixed point with a predetermined acceleration when a work on a belt conveyor passes a predetermined position, calculates the moving distance of the work, and the work passes the predetermined position. The distance comparison means for detecting whether or not the value corresponding to the moving distance after that has been reached is used, and the hand is caused to perform the gripping operation based on the detection result.

[Action]

This device detects the moving distance after the work passes a predetermined position and the moving distance of the hand by a distance comparing means, and determines whether the hand reaches the position of the work based on the detection result. Is determined and a gripping operation is performed.

[Example of device]

FIG. 1 is an overall configuration diagram of the present invention, in which the same reference numerals as in FIG. 6 indicate the same or corresponding parts, (3c) is a speed detecting means for detecting the speed of the belt conveyor (3), and (5) is This is a detection means for detecting that the work (4) has passed a predetermined position, and a photoelectric device is used in this embodiment. (20a) is a fixed point standby means for waiting the hand (1b) at a fixed point immediately above the above predetermined position, (20b) is an arm acceleration / deceleration means (20c) for accelerating / decelerating the arm (1a), and a belt conveyor ( 3) Speed comparison means for comparing the speed of the hand (1b),
In (20d), the speed of the hand (1b) is the belt conveyor (3).
1/2 of the moving distance from the stopped state to the speed of the belt conveyor (3) after exceeding the speed of
The arm accelerating / decelerating means (20e) that operates to decelerate the hand (1b) when it is equal to, the moving distance of the hand (1b) after entering the deceleration state is from the stopped state to the belt conveyor (3). A distance comparing means for operating the hand (1b) at a constant speed when it becomes equal to 1/2 of the moving distance to reach the speed, (21) is a distance calculating means for calculating the moving distance of the hand (1b) , (22) are hand control means for causing the hand (1b) to perform a gripping operation in response to an actuation signal from the distance comparison means (20e).

Next, details of the embodiment will be described with reference to FIGS. 2 to 5 (a) and (b).

In FIG. 2, (25) is an input / output device for exchanging signals with external devices, (26) is a CPU, (27) is RAM for storing external signals and user programs, and (28) is FIG. 5 ( This is a ROM in which the programs shown in a) and (b) are stored.

Next, the operation will be described with reference to FIGS. 5 (a) and 5 (b). In the procedure (100), the hand (1b) is set at the point R ₁ shown in FIG. 3, that is, the point immediately above the site where the work (4) is detected by the detector (5). In step (101), the current speed V _CURR and the moving distance S are set to zero. In step (102), the detector (5) waits for detection of the work (4). Procedure when detected (103)
Then, the acceleration ΔV increases the unit time Δt by ΔV · Δ
Add t to the current speed V _CURR . The result of this addition is the next speed V
Set to _NEXT . Furthermore, only the distance moved in Δt seconds is added. This distance is represented in FIG. 4 as the area ΔS ₁ for Δt seconds. In step (104), the next speed V _NEXT is output to the servo section to drive the arm (1a). Procedure (10
In step 5), move the next speed V _NEXT to the current speed V _CURR . Procedure (106)
And the current speed V _CURR is the speed V _MAX of the belt conveyor (3)
Check whether or not. If the speed has not reached V _MAX , the procedure moves to step (107) and waits until the unit time Δt is reached.
When the unit time Δt is reached, the procedure moves to step (103), and the same processing is repeated thereafter. As a result of this processing, the speed is increased by the acceleration ΔV as shown in FIG. 4, and when the speed reaches the speed V _MAX of the belt conveyor (3), it is judged as “YES” in step (106) and the process proceeds to step (108). Here half of the value of the acceleration distance S Hand (1b) reaches velocity V _MAX, hand after exceeding the velocity V _MAX (1
Set as the target distance that b) moves. In step (109), it is checked whether the target distance is "positive". "Positive" means "N
"O" and proceed to step (110). Here, the acceleration amount ΔV · Δt for the unit time Δt with the acceleration ΔV is added to the current speed V _CURR . The result of this addition is set to the next speed V _NEXT . Further, the distance ΔS ₂ preceding the belt conveyor (3) in Δt seconds is subtracted from the target distance S. In step (111), output the next speed V _NEXT to the servo section and drive arm (1b). In step (112), the next speed V _NEXT is moved to the current speed V _CURR , and in step (113), the time reaches Δt, and the process moves to step (109). The target distance is gradually reduced by ΔS ₂ by repeating steps (109) to (113).

When the target position S becomes “zero” in step (109), that is,
In FIG. 4, the hand (1b) is a belt conveyor (3).
The distance to the belt conveyor (3) after _exceeding the speed V _MAX of the belt conveyor (3) is from the point R ₁ to the speed V _MAX of the belt conveyor (3).
When 1/2 of the moving distance S to reach
Go to 4).

In step (114), it is checked whether the current speed V _CURR of the hand (1b) has _decreased to the speed V _MAX of the belt conveyor (3). If the speed has not reached V _MAX yet, enter “NO” and proceed to step (115). Here, the unit speed _{ΔCU is} decelerated by the acceleration ΔV from the current speed V _CURR to the next speed V _MEXT , and in step (116), the next speed V _MEXT is output to the servo unit to drive the arm (1a). . Set the next speed V _NEXT to the current speed V _CURR in step (117). Going to the step (114) while keeping Δt in the step (118).

Thereafter, steps (114) to (118) are repeated to obtain ΔV
Decelerate by Δt. The speed of the belt conveyor (3)
When it becomes equal to V _CURR, it is judged as “YES” in the step (114) and the process moves to the step (119). In this state, the hand (1b) is directly above the work (4), so the gripping operation is instructed in step (119). The work (4) gripped in the procedure (120) is commanded to be transported to a predetermined place.

Work (4) on the belt conveyor (3) according to the above procedure
Can be gripped by the hand (1b).

In the above embodiment, the standby position of the hand (1b) is located directly above the detection point of the detector (5) as shown in FIG. 3, but the present invention is not limited to this, and the detector (5) Alternatively, the hand (1b) may be set at a predetermined position where the difference in the distance is known in advance, and the hand (1b) may be put on standby.

That is, when the standby position of the hand (1b) is away from point R _{1 in} FIG. 3 by the traveling direction S ₀ of the belt conveyor (3),
The belt conveyor (3) starts from time t ₀ shown in FIG.
The predetermined distance S ₀ to the moving distance S until reaching the speed V _MAX of
In step (108), use "(S-S ₀ ) / 2 →
The following program processing may be performed as "S".

Conversely, the standby position of the hand (1b) is the belt conveyor (3).
When the vehicle is separated by a predetermined distance S _{0 in the} direction opposite to that of step S1, “(S + S _0/2 → S)” may be set in step (108).

According to the above-described embodiment, the movement distance S is calculated each time the work (4) is detected, so at least the work (4) is detected.
If the speed of the belt conveyor (3) is constant after the detection of, the holding operation of the fixed point is performed without changing the standby position of the hand (1b) even if the speed is changed. You can

[Effect of device]

As described above, the present invention provides a robot control device for placing a work on a belt conveyor that moves at an arbitrary constant speed, accelerating and decelerating the hand from a fixed point with a constant acceleration to catch up with the work, and hold the work. When it is detected that has passed a predetermined position, the hand waiting at a fixed point is accelerated with a constant acceleration, and the speed comparison means detects that the speed matches the speed of the belt conveyor. The distance moved by the hand to the speed matching point is calculated by the distance calculating means, so that the relative distance difference between the hand and the work is detected at the speed matching point. With this distance difference, the hand is accelerated and decelerated at a constant acceleration and a constant deceleration with the same absolute value, and when the distance difference becomes zero, the hand grips the work.

Therefore, the speed matching point of the hand and the belt conveyor, and the distance that the hand moves to this matching point are detected and calculated for each work, so even if the speed of the belt conveyor is changed, the hand waits. The gripping operation can be performed while the position is fixed without changing the position.

[Brief description of drawings]

1 to 5 (a) and (b) show an embodiment of a robot controller according to the present invention, FIG. 1 is an overall configuration diagram, and FIGS. 2 to 5 (b) are embodiments. Specifically,
FIG. 2 is a block diagram of the computer system, FIG. 3 is a plan view of essential parts, FIG. 4 is an explanatory diagram, and FIGS. 5 (a) and 5 (b) are flow charts of the program. 6 to 8 show a conventional robot controller,
FIG. 6 is an overall configuration diagram, FIG. 7 is a diagram corresponding to FIG. 3, and FIG. 8 is an explanatory diagram. In the figure, (1) is a robot, (1a) is an arm, (1b) is a hand, (3) is a belt conveyor, (3c) is a speed detecting means, (4) is a work, (5) is a detecting means, ( 21) is a distance calculation means, (21a) is an arm control means, and (22) is a hand control means. The same reference numerals in the drawings indicate the same or corresponding portions.

Claims (1)

[Scope of utility model registration request] 1. A work is placed on a belt conveyor which moves at an arbitrary constant speed, is accelerated and decelerated from a fixed point at a constant acceleration / deceleration, catches up with the work, and the work is attached to the end of the arm by the hand. In what is gripped, a work detection means for detecting that the work has passed a predetermined position, and a fixed point separated by a predetermined distance S ₀ from the detection point of the work detection means in the traveling direction or the anti-traveling direction of the belt conveyor. At a fixed point waiting means for holding the hand, and an arm accelerating means that operates by a detection signal of the work detecting means to accelerate the hand from the fixed point in the traveling direction of the belt conveyor at a constant acceleration, the hand and the hand. A speed comparing means for comparing the speed of the belt conveyor, and this speed comparing means detects that the speed of the hand and the belt conveyor match. The distance calculating means for liquidating the moving distance S of the hand from the fixed point, and the hand further preceding the belt conveyor by the distance L represented by the following equation or the following equation from the speed coincidence point. First distance comparing means for detecting movement, and arm decelerating means for decelerating the hand at a deceleration having the same absolute value as the acceleration by the detection signal of the distance L by the first distance comparing means, Second distance comparing means for detecting that the hand has moved further ahead of the belt conveyor by the distance L at the deceleration from the detection point of the distance L by the first distance comparing means. And a hand control means for causing the hand to grip the work by the detection signal of the distance L by the second distance comparison means. . When the predetermined distance S ₀ is on the traveling direction side of the belt conveyor with respect to the detection point Distance L = (moving distance S−predetermined distance S ₀ ) / 2 The predetermined distance S ₀ is the belt with respect to the detection point When the conveyor is on the side opposite to the traveling direction Distance L = (movement distance S + predetermined distance S ₀ ) / 2