JPH06289923A - Automatic teaching method for robot - Google Patents

Abstract

PURPOSE:To shorten teaching work time and to execute highly precise teaching by operating a robot while pressing a work to a working tool based on coarse teaching points and a pressing force direction, setting the rocus of the force control operation of the robot to be a teaching point and executing storage into a memory in synchronism with the sampling period of force control. CONSTITUTION:The work 4 grasped by a hand 2 is guided on the working route of the work 4 in the working tool 15, the positions P1 and P2 are set to be the coarse teaching points and are stored in the memory of a robot control board 10. A representative normal direction against a work surface between the coarse teaching points P1 and P2 is taught as a pressing direction F1 to an edged tool 17 fixed to the working tool 15. A force control operation is executed for the work 4 in such a way that desired force operates on the edged tool 17 fixed to the working tool 15, and the rocus is generated as the teaching point. The encoder shafts of the motor shafts 6 at positions p1-p16 at every time synchronized with the sampling periods of the force control of the robot rocus are stored in the memory of a robot controller as CP teaching data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic teaching method for a robot using force control, in which a motion locus of the robot under force control is stored as a teaching point in a memory of a control device.

[0002]

2. Description of the Related Art As an automatic teaching method for a robot to which force control is applied, Japanese Patent Application Laid-Open No. 3-71135 discloses a tool gripping type previously filed by the present applicant. This is an automatic teaching method for a robot when a machining tool is fixed to a tool holder at the tip of the robot and a workpiece fixed by a workpiece fixing jig is machined in the movable range of the robot.

[0003]

The conventional tool gripping type robot has the following problems. When machining a workpiece with multiple machining tools such as grinding, cutting, and polishing, ATC (Auto Tool Chan
ger) is used, but it takes time to replace the processing tool. A large tool whose processing reaction force and tool weight exceeds the payload capacity of the robot cannot be used, and processing efficiency decreases. Therefore, when the work shape is relatively small and lightweight, it is preferable to adopt the work holding robot.

However, in the work-holding type robot, when machining a complex-shaped work that requires high precision, the number of teaching points is large and the teaching work takes time. When machining a complex-shaped workpiece, it is often difficult to accurately check the contact surface with the operator's eyes in order to accurately apply the workpiece to the blade of the machining tool at an appropriate position. An object of the present invention is to provide an automatic teaching method for a robot, which can shorten the teaching work time in a workpiece gripping robot and can perform highly accurate teaching.

[0005]

According to the present invention, in an industrial robot to which force control is applied, a teaching reproduction robot, a workpiece to be held by a hand of the robot, and grinding fixedly arranged in a movable range of the robot. , A plurality of processing tools required for the grinding, cutting, polishing, etc. according to processing steps such as cutting, polishing, a force sensor provided between the robot tip and the hand, and a controller for the robot. Configure and teach the robot roughly the position of the workpiece with respect to the machining tool,
The position of the work is used as a rough teaching point, the direction of the pressing force of the work on the machining tool is taught between the rough teaching points, and the desired force is applied continuously based on the rough teaching point and the direction of the pressing force of the work on the machining tool. The robot while operating the workpiece against the machining tool, the locus of the force control operation of the robot is used as a CP teaching point, the teaching point data is stored in the memory of the control device, and the force control operation of the robot is controlled by the force control operation. This is an automatic teaching method for robots that is performed at each time synchronized with the sampling cycle. Further, it is an automatic teaching method for a robot, in which the force control operation of the robot for storing the CP teaching point data in the memory of the control device is carried out every time the robot moves a certain distance.

[0006]

Embodiments of the present invention will be described in detail with reference to FIGS. FIG. 2 is a diagram for generating CP teaching points from rough teaching points,
FIG. 3 shows the structure of a grinding robot for carrying out the automatic teaching method of the present invention. The robot main body 1 and a control device 10 for controlling the main body are the main components.

It has a hand 2 for gripping the work 4, and a servo motor M ₁ for rotating the gripped work 4, a servo motor M ₂ for twisting, a servo motor M ₃ for bending, and a servo for moving forward and backward. A motor M ₄ , a servo motor M ₅ for moving up and down, a servo motor M ₆ for rotating, and a force sensor 3 for performing force control are provided between the tip of the robot body 1 and the hand 2. A plurality of processing tools 15 required for the grinding, cutting, polishing, etc., which have a rotating mechanism and are adapted to processing steps such as grinding, cutting, polishing, etc., are fixedly provided within the movable range of the robot body 1. The processing tool 15 fixes a blade 17 such as an end mill to a rotating device 16. For processing tools, select a rotating device or cutting tool depending on the application such as grinding, cutting, or polishing.

The work 4 is composed of a base material 5 and projections 6, and the projections 6 project in an irregular shape outside the outer edge of the base material 5. Such workpieces include, for example, castings, and burrs and sprue marks become projections. Robot body 1
Then, the control device 10 is connected by the power line 11 and the signal line 12.

With the configuration of FIG. 3 as described above,
It has the following effects. It has a rotating mechanism and fixes a plurality of machining tools 15 to the machining tool base 30 according to machining processes such as grinding, cutting and polishing. In FIG. 3, only one machining tool is shown. As the work used for rough teaching and automatic teaching, a model work from which the protrusions 6 have been removed by hand machining or the like is used, and the model work is gripped by the robot hand 2. Processing tool 15
Then, the work 4 gripped by the hand 2 is guided to the machining path of the work 4 by a teaching box (not shown), and its positions P1 and P2 (shown in FIG. 2) are set as rough teaching points in the memory of the robot control panel 10. Memorize (rough teaching work).

At this time, the teaching point may be taught at a position 3 to 6 mm away from the machining tool as long as the work is within the distance that the work follows the tool in the force control operation. The roughness of this accuracy depends on the magnitude of the gain of force control. The larger the force control gain, the farther the teaching can be performed from the work and the tool. As shown in FIG. 2, the position where the work and the cutting tool are roughly taught is the position P1, which is the same position as the arbitrary position G of the work.
This is indicated by P2. With automatic teaching, the workpiece follows the tool,
The rough teaching points P1 and P2 do not coincide with the arbitrary position G of the work. Further, a typical normal direction to the work surface between the rough teaching points P1 and P2 is taught as a pressing force direction F1 to the cutting tool 17 fixed to the machining tool 15.

In this way, the rough teaching points P1 and P2 in the operation path of the work 4 and the direction F of the pressing force to the machining tool are set.
1 and work feed speed (not shown) are taught in sequence,
The rough teaching program is stored in the memory of the control device 10.

When the trajectory of the force control operation is taught by following the work 4 using the force control (automatic teaching), in order to reduce the frictional resistance between the work 4 and the cutting tool 17, the same size and shape as the cutting tool are used. The robot automatic teaching method of the present invention can be applied without any problem even if a teaching tool model without a blade is used. Although the robot main body 1 is of a 6-axis cylindrical coordinate type in FIG. 3, the posture and the processing reaction force for processing the protrusion of the work are
Other types of robots may be used as long as the load resistance and the composition are satisfied.

In the robot constructed as shown in FIG. 3, the work 4 is force-controlled so that a desired force acts on the cutting tool 17 fixed to the machining tool 15, and the locus is generated as a teaching point. . In this automatic teaching, a hybrid control that performs two controls at the same time, that is, force control that continuously pushes the workpiece and machining tool at the robot arm tip in the force control direction with a desired force, and position control reproduction of the robot based on the rough teaching point. Take control.

The automatic teaching method of the present invention will be described based on the flow chart of the present invention (FIG. 1) and a model diagram (FIG. 2) for generating CP teaching points from rough teaching points. The rough teaching work, which is the basis of automatic teaching, is performed by the operator's robot control. For the workpiece with a curved line in the machining part of FIG. 2, P1,
P2 is the rough teaching point. Further, the direction F1 of the pressing force against the work is taught. Also, the speed at the time of processing and reproducing is taught.

The rough teaching position data of the rough teaching point P1 is read (step 1), and the robot is moved to the position P1 by a normal reproducing operation (step 2). Hybrid control is performed from P1. Next, the pressing force direction F1 to the work and the next rough teaching point position P2 are read (step 3-5), while the tool is pressed to the work in the pressing force direction F1 while moving the tool from P1 to P2 (step 6). At that time, the positions p1 to p16 of the robot trajectory for each time synchronized with the sampling cycle of force control
The encoder values of the motor 6-axis are stored as CP teaching data in the memory of the robot controller (step 7).
CP teaching points p1 to p16 shown in FIG. 2 indicate movements of an arbitrary fixed position G of the work. The distance between the CP teaching points is determined by the speed at the time of machining reproduction taught at the rough teaching work. This operation is repeated until the rough teaching point P2 is reached (step 8-9). When P2 is reached, the same operation is performed until the next rough teaching point is reached (step 4-10).

[0016]

In the embodiment, the automatic generation of the teaching point for the CP reproduction is described, but the interpolation of the interpolation of the encoder value of the motor 6 axis is stored in the memory of the robot controller every time the robot moves a certain distance. It is possible to easily realize teaching point data for reproduction. With the configuration of the present invention, it is possible to shorten the teaching work time and teach a teaching point on a complicated curved path with high accuracy.

[Brief description of drawings]

FIG. 1 is a flowchart of the present invention.

FIG. 2 is a diagram for generating CP teaching points from rough teaching points.

FIG. 3 is a block diagram of an actual machine that implements an automatic teaching method.

[Explanation of symbols]

 1 Teaching reproduction robot main body 2 Hand 3 Force sensor 4 Workpiece 10 Control device 15 Machining tool 16 Rotating device 17 Cutting tool ○ Rough teaching point P1 to P2 × Workpiece fixed position G → Pressing force direction F1 ● CP teaching point p1 to p16

Claims (2)

[Claims] 1. A robot, a workpiece to be machined grasped by a hand of the robot, and grinding, cutting, polishing, etc., which are fixedly arranged in a movable range of the robot, according to processing steps such as grinding, cutting, and polishing. The robot is composed of a plurality of required machining tools, a force sensor provided between the tip of the robot and the hand, and a controller for the robot, and roughly teaches the position of the workpiece to the machining tool. Is set as a rough teaching point, and the direction of the pressing force of the workpiece on the machining tool is taught between the rough teaching points. Based on the rough teaching point and the pressing force direction of the workpiece on the machining tool, the desired force is continuously applied. In a teaching playback robot that applies force control to move a robot while pressing a workpiece against a machining tool, the locus of the force control operation of the robot is used as CP teaching points at each time synchronized with the sampling cycle of force control. An automatic teaching method for a robot, characterized in that the teaching point data is stored in a memory of a control device. 2. The automatic teaching method for a robot according to claim 1, wherein the locus of the force control operation of the robot is stored in a memory of the control device as teaching point data every time the robot moves a certain distance.