JP2820502B2 - Robot arm control method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot arm for performing an arch motion in which an arm tip moves from point A to point B and reciprocates in the Z-axis direction in an XYZ coordinate system. In the control method.

2. Description of the Related Art As shown in FIG. 4, when a workpiece is gripped by a chuck provided at a tip of a robot arm and the tip is moved from a point A to a point B, there is an obstacle between the two points. An arch motion that not only moves an arm tip in a horizontal plane but also moves up and down simultaneously is known.

In such a case, a new work cannot be transferred to the B point because the previous work still remains at the B point. Is determined, and if the transfer is possible, the work is transferred to the B point, but if transfer is not possible, the work is moved to the standby C point set above the B point. .

SUMMARY OF THE INVENTION However, in the above-described conventional example, it is necessary to determine the movement position between the B point and the C point when the arm tip is located at the A point. If it is judged that there is, and it is possible to move to the B point while moving to the C point, the tip of the arm also moves to the C point, again judges and moves to the B point. There is a problem that it easily occurs.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described problems of the related art, and has as its object to provide a control method of a robot arm that can reduce a loss time with easy control with respect to a change in a state where point B is not possible.

Means for Solving the Problems In order to achieve the above object, the present invention sets a position at which the backward movement in the Z-axis direction is started as a D point, and sets a B position at this D point.
Check the state of the point, move the tip of the arm to the B point if it is possible, and move the tip of the arm to the C point set to the position of the B point in the Z-axis direction if it is not possible. It is characterized by being made to wait.

In the above configuration, the state of the B point is checked at the D point on the movement trajectory from the A point to the B point. Movement can be started, and the determination of B point or C point can be delayed until the point D is reached.
Loss time for a change in the state of a point can be reduced.

Also, by setting the D point to a position where the arch motion starts to return in the Z-axis direction and setting the C point to a position of the B point to the D-axis direction D point, the B point or the C point from the D point is set. The movement in the X and Y directions is the same, and can be controlled only by changing the movement amount in the Z-axis direction. Therefore, not only the control is easy, but also the D point to the B point or It is possible to avoid a situation where the arm tip vibrates while moving to the point C.

Embodiment An embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 1, the robot according to the present embodiment checks the presence / absence of a work at a position where the end portion 1 of the transfer means is set to the point A, and then moves the robot body 3 in the XY directions. While the workpiece is gripped by a chuck (arm tip) 4 which is moved up and down in the Z direction, the presence or absence of the previously transferred workpiece at point B on the mounting table 5 is detected by the sensor 6. The controller 7 is configured to instruct the robot body 3 to transfer the work at the point A.

The chuck 4 is moved horizontally in the X-Y plane in the X direction and up and down in the Z direction, and is moved to the point B with a substantially arc-shaped movement trajectory as shown by a solid line in FIG. When a work is not detected at the point B, that is, when there is no previous work, the next work can be transferred. When a work is detected, that is, when the previous work still remains, the next work cannot be transferred.

A C point, which is a standby position when the B point cannot be transferred, is set immediately above the B point, that is, at a position where the XY position is the same as the B point and only the Z position is different.
Further, a D point for determining whether the chuck 4 is to be moved to the B point or the C point is set at a position where the lowering of the chuck 4 is started on the movement locus from the A point to the B point. The movement trajectory from the point D to the point C has a substantially arc shape as shown in FIG.

The operation of the above configuration will be described with reference to the flowchart of FIG.

Chuck 4 is A regardless of B point availability
Start moving from point to point D. First, it starts to rise in the Z direction, and horizontal movement in the X direction is added to this. The movement in the X direction is a substantially constant speed up to the XY position of the B point or the C point as shown in FIG.
The movement in the Z direction is decelerated according to the ascending position, and becomes zero at the D point.

When the chuck 4 reaches the point D, the state of the point B is checked. If the transfer is possible, the chuck 4 moves at a positive speed in the Z direction,
The workpiece is moved at the speed indicated by the solid line in FIG. If the transfer is not possible, the chuck 4 moves at a slightly slower speed than the case of moving to the point B as shown by the imaginary line in FIG. 3, and stops at the point C. Thereafter, when the point B is ready to be transferred, the chuck 4 is moved to the Z position.
Then, the workpiece is placed at point B.

In this embodiment, the movement start time based on the state of the point B is set to the point D on the movement trajectory instead of the point A, so that the movement start time of the chuck 4 can be advanced. Loss time of moving work can be reduced.

Further, by setting the point D as the descending point on the movement trajectory, the movement toward the point B and the movement toward the point C can be performed only by changing the movement amount in the Z direction. In the case of the present embodiment, the travel time to both the B and C points is set to be the same, so that the travel distance can be changed according to the travel speed. Therefore, the control accompanying the change of the movement position is easy, and the chuck 4 is less likely to vibrate due to the change.

The present invention can be configured in various modes in addition to the embodiments described above. For example, in the above embodiment, the movement locus from the D point to the B point and the C point are separately set, but the C point may be set so as to be positioned on the orbit.

Advantageous Effects of Invention The present invention has the above configuration and operation, so that the movement start of the arm tip can be hastened, and the movement control of the arm tip for the change in the state of the B point is performed only by the amount of return in the Z-axis direction. As a result, the loss time can be reduced by easy control, and the vibration of the tip of the arm when moving to the point B or the point C can be reduced.

[Brief description of the drawings]

1 is a schematic configuration diagram of an embodiment of the present invention, FIG. 2 is a flowchart thereof, FIG. 3 is a movement graph in XY directions and Z directions, and FIG. 4 is a schematic configuration diagram of a conventional example. 4 ... Arm tip 6 ... Sensor

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Eizo Ichinose 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-57-113116 (JP, A) JP-A-4 -2482 (JP, A) JP-A-1-108604 (JP, A) JP-A-60-138611 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B25J 9/10, 13/00 B25J 9/00

Claims (1)

(57) [Claims] 1. A robot arm control method for performing an arch motion in which an arm tip moves from a point A to a point B in an XYZ coordinate system and reciprocates in the Z axis direction. The position at which the movement is started is set as the D point, and the state of the B point is checked at the D point. If the state is valid, the tip of the arm is moved to the B point. A method for controlling a robot arm, comprising: moving a tip of an arm to a C point set at a side position to wait;