JPS6257005A - Robot control system - Google Patents

Abstract

PURPOSE:To control the operation of the end effector of a robot exactly and to prevent a work from being damaged by setting the operation area of the end effector by generating three-dimensional software limits. CONSTITUTION:The area where the end effector such as a robot hand is able to operate within the movable range of the robot arm is set as a three- dimensional software stoke limit cube (SSLQ). Namely, the robot is put in teaching mode and moved under commands from a console panel 3 within a range where the robot operates in given environment theta. The robot sets '1' and '0' in memory cells of the SSLQs in its operation area. When a teaching end mode is entered, new three-dimensional SSLs are generated from the track and stroke limits stored in the memory cells. Thus, even if an instruction for entry into the impossible operation area is sent from an NC tape to the robot, a CPU 1 discriminates the stroke limits from the memory contents of the SSLQ stored in a memory 2 and does not execute the instruction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a robot control method, and in particular, to a robot control system in which an area in which a robot cannot operate is set in advance and stored in a memory.
The present invention relates to a robot control method that immediately stops movement of an end effector such as a robot hand (movable part) when it enters this area to prevent accidents such as damage to a workpiece.

(Prior art) In a robot driven by a numerical control device, the maximum range of movement of the arm, hand, etc. (hereinafter referred to as the movable part) is determined, and the movable part may go out of control due to a programming error or some other failure. However, if the movable range is exceeded (overtravel), this is immediately detected and the movable part is brought to an emergency stop. In order to detect such overtravel, limit switches or the like are usually provided at the maximum stroke points on the +X side, -X side, +Y side, and -Y side of the movable range, and a dock is provided on the movable part. overtravel is detected by detecting that the limit switch has been stepped on.

By the way, in a robot driven by a numerical control device, there are areas into which the movable part cannot enter even within the maximum movable range.

For example, when a robot exchanges workpieces on a lathe, if the robot accidentally turns its arm with its hand inside the window of the lathe, the hand will collide with the lathe.

Such abnormal movements of the robot hand are caused by malfunctions in the calculation system of the numerical control device, errors in reading the NC tape, erroneous operations by the operator, abnormalities in the servo system, and the like.

(Problem to be Solved by the Invention) Conventionally, in order to prevent such abnormal movements of robot hands, etc., an overtravel area has been set in software (called a software stroke limit), and a movable part has been set in an overtravel area. A method of preventing damage to the movable parts by immediately stopping the movement of the movable parts upon entry was taken, but this was not an adequate measure.

Therefore, one aspect of the present invention is to solve the problems of the prior art.

(Means for Solving the Problem) The present invention provides a memory means having memory cells corresponding to each cube-shaped divided area obtained by dividing the area in which the end effector of the robot operates into a plurality of areas in three-dimensional directions. , means for storing in each memory cell of the memory means whether the end effector is in the operation a[operable area or in the inoperable area, and means for associating the current position of the end effector with the memory cell. and means for disabling a robot in operation when the end effector is in an inoperable region by means of a signal from the means for associating the current position of the end effector with a memory cell. Provide a control method.

The present invention also provides a robot control system characterized in that each memory cell is made to store whether or not the end effector is in an operable region only during robot teaching operation.

This solves the problems of the prior art described above.

(Operation) In the present invention, the movable region of the end effector of the robot is set by forming a three-dimensional software stroke limit.

Therefore, the operation of the end effector of the robot can be accurately controlled, and damage to the workpiece can be prevented.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. Second
Figures 3 and 3 explain the movable range of the robot. Figure 2 is a side view, and Figures 3 and 3 are elevation views. As shown in Figure 0, the robot has a base a and a first arm. b, second arm C, hand d, etc., and surrounded by diagonal lines A 1
The robot arm is driven within the range of +A2.

In the present invention, within the movable range of the robot arm, an area in which an end effector such as a robot hand can operate is further set using three-dimensional software stroke limit cubes (hereinafter referred to as 5SLQ).

This 5SLQ is used as follows.

(1) When using a robot in a Cartesian coordinate system, it is assumed that the area in which the robot's end effector can operate is surrounded by a Cartesian body, and this rectangular parallelepiped is divided into nXmX1 equal parts of nXmX1. small cuboids (
A plurality of memory cells are provided corresponding to each cube. Then, during the teaching operation of the robot, each of these memory elements is made to store information as to whether or not the end effector can operate.

For example, n X m Set.

(2) When using a robot in an axial coordinate system, each of the robot's three basic axes (for example, θ, W, U or Z, θ, R) is divided into equal parts n, m, and fL, and the operable area is n
Divide into m x 1 pieces.

A memory cell is made to correspond to each divided area, and whether or not each divided area can be operated is set.

FIG. 4 is an explanatory diagram of the movable region of the robot end effector set in this way, and illustrates an example in which the movable region B of the end effector is set within the rotation range A2 of the robot arm. There is.

FIG. 1 is a block diagram showing an example of a numerical control device. The numerical control device is a central processing unit (CPU)1. Memo lJ
2, teaching operation m3, operation panel 4, CRT5. Tape reader 6, data bus 7, axis controller 8 that drives the servo motor
, interface 9, input/output capo) (Ilo), etc. The normal operation of each of these elements is well known to those skilled in the art, so a detailed explanation will be omitted.

Next, the teaching of 5SLQ according to the present invention will be explained.

Set the robot to teaching mode, and according to the command of teaching operation a3, move the robot within the movable range with θ of the given environment.The robot will calculate the SSLQ (nX
1.0 is set in the memory cells of each area divided into mXu.

When the robot is set to 5SLQ teaching completion mode,
A new three-dimensional software stroke limit is created from the trajectory stored in the memory cells and the conventional stroke limit.

For example, if the trajectory is to the left of half the stroke,
This new trajectory becomes the limit of left-side movement. The memory cells surrounded by the remaining conventional stroke limits and trajectories are
1 is set to make the region operable, and other memory cells are set to 0 to become the non-operable region.

After setting 5SLQ in this way, when operating the robot, even if a command is issued from the NC tape for the robot to enter an inoperable area, the CPU 1 will not be able to operate the 5SLQ memory cell stored in memory 2. The stroke limit is determined from the content of the command, a process is performed to prevent the command from being executed, and an alarm is generated by an alarm device (not shown). In addition, in the above embodiment, the operating range of the end effector is divided into cubes, but in the case of the θ axis of the robot,
The rotation angle of the arm may be divided into n equal parts to divide the operating range of the end effector into fan-shaped small spaces, and the memory cells may be made to correspond to the small spaces.

(Effects) According to the present invention, it is possible to reliably prevent an end effector such as a robot hand from entering an inoperable area, and damage to a workpiece can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a numerical control device that drives the robot, and FIGS. 2 to 4 are explanatory diagrams of the robot operation. DESCRIPTION OF SYMBOLS 1...Central processing unit, 2...Memory, 3...Teaching operation panel, 4...Operation panel, 5...CRT, 6...Tape league, 7...Data bus, 8 ...Axis controller,
9... Ink face, 10... Input/output boat. Patent applicant: Representative of FANUC Co., Ltd. Patent attorney: Minoru Tsuji Figure 3

Claims (2)

[Claims] (1) A memory means having a memory cell corresponding to each cube-shaped divided area obtained by dividing the area in which the end effector of the robot operates into a plurality of areas in a three-dimensional direction, and the end effector is in the operable area. means for storing in each memory cell of the memory means whether the end effector is in an inoperable region or in an inoperable region; and means for associating the current position of the end effector with the memory cell; 1. A robot control method comprising: means for disabling a robot in operation when an end effector is in an inoperable region using a signal from a means for making the robot correspond to a cell. (2) The robot control method according to claim (1), wherein each memory cell is made to store whether or not the end effector is in a movable region only during a teaching operation of the robot.