Data processing: generic control systems or specific application – Specific application – apparatus or process – Robot control
Reexamination Certificate
1998-07-16
2001-12-18
Lee, Thomas (Department: 2182)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Robot control
C700S029000, C700S031000
Reexamination Certificate
active
06332101
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an off-line teaching method which makes it possible to accurately estimate the amount of correction of teaching data previously obtained by instructing a logical robot model by using an off-line teaching apparatus.
2. Description of the Related Art
Recently, in order to apply the robot to various workings, in general, a variety of tools are attached to the face plate of the robot arm to allow the robot to perform working.
A large number of techniques for instructing the robot as well as a large number of techniques for making various types of correction for the instruction data have been hitherto suggested. For example, a method has been suggested in relation to the instruction technique for the robot (see Japanese Laid-Open Patent Publication No. 5-27828), in which information necessary for the robot working to be used is given in conformity with the request of a user as accurately as possible, and the burden for the user is mitigated as less as possible.
In relation to the technique for correcting the instruction data, the following methods have been suggested, including, for example, a method in which the revision for the instructed point and the correction for the instructed locus can be easily executed under the same operation condition as that used during playback even at a place separated from the working job site so that the burden for the operator to perform the operation for revising the instruction is mitigated (see Japanese Laid-Open Patent Publication No. 8-286726); a method in which the positional discrepancy can be automatically corrected for all striking positions with a high degree of accuracy (see Japanese Laid-Open Patent Publication No. 7-325611); a method in which the position of the robot is corrected by using a neural network (see Japanese Laid-Open Patent Publication No. 6-114769); a method in which the revising operation sensuously comprehensible for the operator can be performed when the conversion data for the robot operation is revised upon occurrence of malfunction in the operation range concerning the revised instruction data (see Japanese Laid-Open Patent Publication No. 5-289730); a method in which the repeated logical operation based on the modified Powel method is applied for respective elements of unknown variable matrix and constant matrix to ensure the absolute positional accuracy of an arm-type multi-joint robot by using only the angle of rotation of the arm axis while avoiding the measurement on the rectangular coordinate in order to further improve the accuracy and increase the computing speed (see Japanese Laid-Open Patent Publication No. 6-274213); and a method in which the setting error of a certain constant and the setting error of tool offset are automatically corrected by using setting data for a robot of the multi-joint type attached with a tool at its wrist (see Japanese Patent No. 2520324).
In relation to the setting of the tool cusp point, a method has been suggested (see Japanese Laid-Open Patent Publication No. 7-191738), in which the tool cusp point can be set for a desired attitude in accordance with a simple procedure by utilizing a simple setting jig even when the design data is not available. A method, which is based on the use of CAD data, has been suggested (see Japanese Laid-Open Patent Publication No. 8-286722), in which it is unnecessary for the operator to thoroughly input the initial setting data, the working procedure data, and the working operation data one by one so that the amount of input to be performed by the operator is greatly decreased. A method, which relates to presentation of locus, has been suggested (see Japanese Laid-Open Patent Publication No. 8-174454), in which the relative positional relationship between a workpiece and an actual position of an actually operating tool can be easily and accurately recognized when a workpiece is retracted from the working position.
However, in the illustrative conventional techniques concerning the off-line teaching described above, the working point of the robot is subjected to positional adjustment with a high degree of accuracy by using the attitude which differs as far as possible, with respect to the fixed point in the space at the working site at which the actual robot is installed. Moreover, the attitude has been arbitrarily determined by the judgement of the operator.
As described above, the conventional technique entrusts the judgement of the individual operator. Therefore, an inconvenience arises in that it is not necessarily possible to obtain the teaching data which is appropriate to calculate the correction amount. Further, a problem arises in that the conventional technique requires a long time, because the attitude is thought of at the working site.
SUMMARY OF THE INVENTION
The present invention has been made taking the foregoing problems into consideration, an object of which is to provide an off-line teaching method which makes it possible to stably obtain teaching data usable to accurately estimate the correction amount, and decrease the number of working steps based on the use of an actual robot.
According to the present invention, there is provided an off-line teaching method for correcting robot models to be used in an off-line teaching system, comprising a first step of performing multi-point multi-attitude teaching capable of obtaining the best correcting calculation result of those obtained with a logical robot model as a correction objective, by using an off-line teaching apparatus; a second step of downloading teaching data obtained in the first step from the off-line teaching apparatus to an actual robot as a correction objective; a third step of revising the teaching data on the basis of a difference between an actual target point and an operation point of the actual robot based on the teaching data; and a fourth step of uploading teaching data obtained after the revision to the off-line teaching apparatus to estimate and calculate a correction amount by using the uploaded data.
That is, the multi-point multi-attitude teaching is performed in the first step to create a plurality of attitudes capable of obtaining the best correcting calculation result by using the logical robot model as the correction objective. The teaching data is downloaded to the actual robot in the second step. In the next third step, the teaching data is revised on the basis of the difference between the actual target point and the operation point of the actual robot based on the teaching data. The teaching data, which is obtained after the revision, is uploaded to the off-line teaching apparatus. The uploaded data is used to estimate and calculate the correction amount. The correction amount concerning the actual robot installed at the working site is reflected to the logical robot model virtually constructed on the off-line teaching apparatus.
According to the present invention, the off-line teaching apparatus is used to perform the multi-point multi-attitude teaching capable of obtaining the best correcting calculation result for the logical robot model as the correction objective so that the teaching data to be downloaded to the actual robot is obtained. Therefore, it is possible to stably obtain the teaching data capable of accurately estimating the correction amount as compared with the conventional teaching data depending on the judgement of the individual operator.
As a result, it is unnecessary to consider the attitude at the working site, and it is enough to perform only simple positional adjustment. Thus, it is possible to decrease the number of working steps to be performed by using the actual robot.
In a preferred embodiment of the method described above, the first step comprises an error model-preparing step of preparing an error model corresponding to a model of the actual robot; a teaching step of performing the multi-point multi-attitude teaching by using the off-line teaching apparatus; an estimating calculation step of estimating and calculating the correctio
Aoki Shinji
Kaneko Masakatsu
Cao Chun
Honda Giken Kogya Kabushiki Kaisha
Lee Thomas
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