JP2017217738A - Robot work teaching method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a robot work teaching method which performs teaching of three-dimensional measurement data obtained by using an ultrasonic distance meter to a multi-axis robot, and enables feedback control to perform position control of working state by using the taught data when controlling the multi-axis robot.SOLUTION: A robot work teaching method is given in which a robot side electric cutting tool 10R is attached at the tip of a work arm 31 of a multi-axis robot 30 and a work piece 11R is worked by the robot side electric cutting tool 10R. In the robot work teaching method, work operations of an electric cutting tool 10T for work teaching are measured three-dimensionally by using an ultrasonic distance meter when a worker works the work piece 11T by using the electric cutting tool 10T for work teaching and recorded as work teaching data 24. The tip of the work arm 31 of the multi-axis robot 30 reproduces the work operation based on the recorded work teaching data 24, and position of the robot side electric cutting tool 10R is measured by the ultrasonic distance meter in the multi-axis robot 30 so that correction control of the position of the robot side electric cutting tool 10R is performed based thereon.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a robot work teaching method when a workpiece is automatically machined by a multi-axis robot.

  In the mold finishing process, the surface is polished with a grindstone, and it has been proposed that this work be taught (teaching) to a multi-axis robot (Patent Document 1).

  To teach work to a multi-axis robot, a skilled worker measures the work actually performed with a router (manual cutting tool) etc. based on motion capture and image information, and uses this as 3D coordinate data Therefore, it has been proposed to control a multi-axis robot (Patent Documents 1 and 2).

Japanese Patent No. 2665897 JP 2011-200997 A JP2015-85496A Japanese Patent Application Laid-Open No. 07-223190 Japanese Patent Laid-Open No. 2003-340619 JP 2013-117877 A

  However, since the accuracy of position data by motion capture and image information is poor, it is difficult to perform accurate polishing even if coordinate data is stored in a multi-axis robot.

  For this reason, Patent Documents 1 and 3 propose that a multi-axis robot is provided with a force sensor, and the force sensor adjusts the contact pressure of the grindstone to perform machining while keeping the force applied to the workpiece constant. ing.

  However, if the contact pressure of a grindstone or the like is controlled to be constant with a force sensor, a deviation from the stored position data will occur, and if this is accumulated, the position error will increase and control with the stored position data will be difficult. End up.

  Even if the contact pressure is made constant by the force sensor, the grindstone itself is worn by use, and the contact pressure also changes each time. Therefore, accurate polishing is difficult even if the contact pressure is simply pressed.

  The present inventors have proposed a work monitoring system in Patent Document 6 that monitors whether or not a plurality of bolt tightening operations have been properly performed based on position information obtained by ultrasonic waves.

  Ultrasonic distance measurement is comparable to the accuracy of motion capture, but it can also calculate the amount of change following the movement of the cutting tool. For this reason, the present invention has been found by finding an advantage that a feedback amount when controlling a multi-axis robot can be obtained.

  Therefore, an object of the present invention is to solve the above-mentioned problems, teach the multi-axis robot with data measured three-dimensionally using an ultrasonic distance meter, and control the multi-axis robot with the taught data. It is an object to provide a robot work teaching method capable of feedback control of position control of a robot.

  In order to achieve the above object, the present invention provides a robot work teaching method in which an electric cutting tool is attached to the tip of a work arm of a multi-axis robot and a workpiece is processed by the electric cutting tool. The work operation of the teaching electric cutting tool when the workpiece is machined with a cutting tool is measured three-dimensionally using an ultrasonic distance meter, and this is recorded as work teaching data, and the recorded work Based on the teaching data, it is reproduced at the tip of the work arm of the multi-axis robot, and the position of the robot-side electric cutting tool in the multi-axis robot is measured with an ultrasonic distance meter. The robot work teaching method is characterized in that the position of the robot is corrected and controlled.

  The present invention measures the ultrasonic distance of the position of the electric cutting tool during teaching work and during machining by the multi-axis robot, thereby controlling the robot-side electric cutting tool when controlling the multi-axis robot with teaching work data. Based on the actual distance, an excellent effect is achieved in that accurate positioning can be performed by performing position correction.

It is a figure which shows the state which records an operator's operation | work in the robot operation | work teaching method of this invention. It is a figure which shows the state which is working with a multi-axis robot in the robot operation | work teaching method of this invention.

  A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 shows a state in which a skilled worker M processes a workpiece 11T with a teaching electric cutting tool 10T such as a router and stores this as work teaching data.

  The teaching electric cutting tool 10T includes a grindstone 12T at its tip, and polishes the surface of the workpiece 11T by rotating the grindstone 12T at a high speed.

  The teaching electric cutting tool 10T is provided with a force sensor 13 for detecting the contact pressure of the grindstone 12T to the workpiece 11T.

  Two ultrasonic transmitters 14 and 15 are provided on the outer surface of the electric cutting tool 10T for teaching, and at least three ultrasonic receivers 16A, 16В, and 16C are provided around the workpiece 11T to generate ultrasonic waves. A rangefinder is constructed.

  The teaching electric cutting tool 10T and the recording device 20 are connected via a multi-core cable 18 so that the electric motor is rotated by energization from the cable 18 and the rotational speed of the grindstone 12T can be arbitrarily adjusted. It has become. The detection value of the force sensor 13 is input to the recording device 20 via the cable 18, and the transmission of ultrasonic waves from the ultrasonic transmitters 14 and 15 is triggered at a predetermined timing via the cable 18. The ultrasonic reception signals detected by the sound wave receivers 16A, 16В, and 16C are input to the recording device 20 through the signal lines 19a, 19b, and 19c, and the respective distances are measured by the time difference between the transmission and reception. Is stored in the recording device 20.

  Here, the ultrasonic receivers 16A, 16В, and 16C are arranged on points A, B, and C that define the coordinate system of the workpiece 11T.

When the reference origin position of the teaching electric cutting tool 10T is RP ₀ and the working position of the grindstone 12T is RP ₁ , the recording device 20 is between the ultrasonic transmitters 14 and 15 and the ultrasonic receivers 16A, 16В, and 16C. Based on the detected distance data, the coordinates (x ₀ , y ₀ , z ₀ ) of the reference origin position RP ₀ and the coordinates (x ₁ , y ₁ , z ₁ ) of the work position RP ₁ are obtained by calculation. These coordinates are stored, and at the same time, the inclination angles (θ _x , θ _y , θ of lines connecting the work position RP ₁ and the reference origin position RP ₀ with respect to the coordinate system defined by the points A, B, C are stored. _z ), and memorize it. Further, the recording apparatus 20, from the reference origin coordinates _{(x 0, y 0, z} 0) changes the inclination angle changes, the feed rate _{(F xθ, F yθ, F} zθ) as well as calculation and storing for each unit time In addition to this unit time, the detection value P of the force sensor 13 and the rotational speed R of the grindstone 12T are stored.

  A microphone 22 for detecting a cutting sound during cutting and polishing with the grindstone 12T is disposed near the workpiece 11T, and the detected sound is input to the recording device 20 via the signal line 23. The recording device 20 stores the sound frequency corresponding to the grinding wheel peripheral speed and the contact pressure of the force sensor 13 during cutting and polishing from the level of the cutting sound sent from the signal line 23 based on the rotation speed R of the grinding wheel 12T.

  The recording device 20 includes the above-described operation teaching operation of the teaching electric cutting tool 10T from the start of the operation when the skilled worker M processes the workpiece 11T with the teaching electric cutting tool 10T to the completion of the operation. This is stored and used as work teaching data.

  The multi-axis robot 30 shown in FIG. 2 polishes the workpiece 11R based on the work teaching data 24.

  The multi-axis robot 30 is an articulated robot, and a robot-side electric cutting tool 10R of the same type as the teaching electric cutting tool 10T shown in FIG. Similarly, ultrasonic transmitters 14 and 15 and a force sensor 13 are provided, and these are connected to the control device 40 via the multi-axis robot 30 and the cable 32.

  In addition, as described in FIG. 1, ultrasonic receivers 16A, 16В, and 16C are provided around the workpiece 11R on points A, B, and C that define the coordinate system of the workpiece 11R. The detected ultrasonic reception signal is input to the control device 40 via the signal lines 19a, 19b, and 19c. Similarly, the microphone 22 is disposed near the workpiece 11R, and the detected sound is transmitted via the signal line 23. To the control device 40.

  When the workpiece 11R is cut and polished by the multi-axis robot 30, the basic motion of the machining operation is programmed in advance in the control device 40. The electric cutting tool 10 </ b> R performs control by adding correction to the basic operation so that the movement is similar to the work of the skilled worker M.

  At this time, the position data (work teaching data 24) of the teaching electric cutting tool 10T is detected in advance by the ultrasonic transmitters 14 and 15 and the ultrasonic receivers 16A, 16В, and 16C as ultrasonic distance meters. Therefore, the position correction can be performed. In addition, the position of the robot-side electric cutting tool 10R of the multi-axis robot 30 can be further corrected to an appropriate position by detecting the contact pressure of the force sensor 13. The work teaching data 24 is calibrated by relating the position correction amount to the distance data detected during machining of the multi-axis robot 30.

When the workpiece 11R is cut and polished by the multi-axis robot 30, the basic machining operation of the robot-side electric cutting tool 10R can be performed to some extent by programming, but a grindstone performed by a skilled worker during cutting and polishing. Oscillates back and forth, oscillates left and right, or circumferentially oscillates at the tip of the grindstone 12T with the reference origin position RP ₀ as a base point, and changes in contact pressure of the grindstone 12T during these operations It is difficult.

In the work teaching data 24, the tilting angle (θ _x , θ _y , θ _z ) of the teaching electric cutting tool 10T and the feed speed (feed speed) _F xθ, F yθ, stored at F _{z [theta]),} based on this, by reproducing these operations, it is possible to reproduce the work of a skilled worker.

  When reproducing this back-and-forth oscillating motion, left-right oscillating motion, and circumferential oscillating motion, the cutting sound is likely to change, and it is determined whether an appropriate operation is being performed based on the change in the cutting sound. be able to.

  Further, since the grindstone 12R is worn by polishing and its peripheral speed also changes, the rotation speed of the grindstone 12R can be adjusted based on the audio frequency data stored in the work teaching data 24.

  As described above, in the present embodiment, machining by skilled workers is stored as work teaching data, and machining operations similar to those by skilled workers can be performed by reproducing work operations using a multi-axis robot based on this data.

  In the above-described embodiment, the example of the polishing process using the grindstone has been described, but it is needless to say that the present invention can be applied to various processes other than the polishing process.

10T Teaching Electric Cutting Tool 10R Robot Side Electric Cutting Tool 11T, 11R Workpiece 14, 15 Ultrasonic Transmitter 16A, 16B, 16C Ultrasonic Receiver 24 Work Teaching Data 30 Multi-Axis Robot 31 Work Arm 40 Control Device

Claims (4)

  In a robot work teaching method for attaching an electric cutting tool to the tip of a work arm of a multi-axis robot and processing a workpiece with the electric cutting tool, an operator worked the workpiece with an electric cutting tool for teaching. The work operation of the electric cutting tool for teaching is measured three-dimensionally using an ultrasonic distance meter, and this is recorded as work teaching data. Based on the recorded work teaching data, the work arm of the multi-axis robot In addition to being reproduced at the tip, the position of the robot-side electric cutting tool in the multi-axis robot is measured with an ultrasonic distance meter, and the position of the robot-side electric cutting tool is corrected and controlled based on this measurement. Robot work teaching method.   2. The ultrasonic distance meter comprises an ultrasonic transmitter provided in an electric cutting tool for teaching and on a robot side, and at least three ultrasonic receivers arranged around the workpiece. Robot work teaching method.   The teaching electric cutting tool is provided with a teaching-side force sensor that detects a contact pressure with a workpiece, and force data detected by the force sensor is stored in the work teaching data, and the robot-side electric power is detected. The cutting tool is provided with a robot side force sensor for detecting contact pressure with the workpiece, and the multi-axis robot is configured such that the detected value of the robot side force sensor becomes data stored in the teaching side force sensor. The robot work teaching method according to claim 1 or 2, wherein the contact pressure is controlled by the step.   The sound during machining with the electric cutting tool during teaching work is recorded together with the work teaching data, and the sound during machining being reproduced by the multi-axis robot is compared with the sound of the work teaching data, and the robot side electric The robot work teaching method according to any one of claims 1 to 3, wherein a rotational speed of a grindstone of a cutting tool is adjusted.

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