JP3588063B2 - Robot controller - Google Patents

Description

ここで、ＯＶＲ＝β／１００、δはＶ（ｉ）の出力をサーボ系へ出し切っている場合にはδ＝１となり、Ｖ（ｉ）の出力をサーボ系へ出し切っていない場合にはδ＝０となる。
【０１００】
例えば、オーバライド１００％の場合には、
Ｖｏｕｔ（ｉ）＝１＊［Ｖ（ｉ）＋Ａｏｕｔ（ｉ）＊（０＋１／２−１／２）＝Ｖ（ｉ）と、当然の結果が得られる。また、オーバライド５０％の場合には、
Ｖｏｕｔ（ｉ）＝０．５＊［Ｖ（ｉ）＋Ａｏｕｔ（ｉ）＊（δ＋０．５／２−１／２）＝Ｖ（ｉ）／２＋Ａｏｕｔ（ｉ）／２＊（δ−１／４）
であり、
δ＝１の場合；Ｖ（ｉ）／２−Ａｏｕｔ（ｉ）／８
δ＝０の場合；Ｖ（ｉ）／２＋Ａｏｕｔ（ｉ）／８
となる。
【０１０１】
以上説明した処理を行ないながらコーナ部を含む経路動作を行なった場合にオーバライド値の高低が軌跡に与える影響について、オーバライド率３０％の場合を例にとり、図１５、図１６を参照して説明する。コーナ部を含む経路動作としては、図１４に示すように、位置Ｇ１から位置Ｇ２への直線動作と位置Ｇ２から位置Ｇ３への直線動作を滑らかに接続したものを考える。両動作のプログラム速度は等しいものとする。
【０１０２】
×印は教示点Ｇ１、Ｇ２、Ｇ３を表わし、★印は最終的にサーボ系へ出力される移動指令に対応する補間点の位置（補間位置）を表わしている。コーナー部は符号Ａで示されている。一方、範囲Ｂは、始動のための加速及び停止（位置決め）のための減速の区間を表わしている。
【０１０３】
本例の場合、コーナー部Ａでは速度一定で★印は等間隔で並ぶが、加減速区間Ｂでは、★印の間隔が徐々に拡大あるいは縮小している。符号ｑ１、ｑ２、ｑ３はコーナー部Ａ内の軌跡を代表する補間点で、コーナー部においてフィルタ部からの出力Ｄ１、Ｄ２に対応する移動区間を形成する。
【０１０４】
また、符号ｐ１、ｐ２、ｐ３、ｐ４は加速区間Ｂ内の軌跡を代表する補間点で、加減速区間におけるフィルタ部からの出力Ｄ１、Ｄ２に対応する移動区間を形成するものである。なお、実際に生成される補間点（★印）の数は遥かに大きいが表示のために少数で簡略描示した。
【０１０５】
図１５を参照すると、図の左上部に示したように、オーバライド１００％でロボットを動作させた場合のコーナー部Ａの軌跡は、図１４に示した通りで、フィルタ部からの出力Ｄ１、Ｄ２に対応する補間点ｑ１、ｑ２、ｑ３を通る軌跡が得られる。
【０１０６】
これに対してオーバライド３０％でロボットを動作させた場合のコーナー部Ａの軌跡は、図１５の右上部に示したようになる。上述したオーバライドの処理（β＝３０）により、フィルタ部からの出力Ｄ１、Ｄ２に対応する補間点ｑ１、ｑ２、ｑ３が、より多数の補間点ｑｄ１〜ｑｄ９（符号は一部のみ表記）に変換される。各区間の計算式は図中に併記した通りである。
【０１０７】
ここで重要な事は、これら補間点ｑｄ１〜ｑｄ９は、元のオーバライド１００％時の軌跡上に乗っていることである。この性質は、オーバライド率３０％でなくとも同様に保証されている。一般には、オーバライド値１００％時の補間点を基準にして、オーバライド値に反比例する数の補間点が出力され、しかもそれらはオーバライド値１００％時の軌跡上に並ぶように形成される。従って、オーバライド値の高低によらず、同じ軌跡がコーナー部でも得られることになる。
【０１０８】
図１５の左下部及び右下部には、フィルタ部出力段階の移動指令Ｄ１、Ｄ２が、分割出力される様子がセグメントで表示されている。本例のように、一定速度でコーナー部を通過する場合は、各セグメントの高さは一定となる。なお、コーナー部を形成する２つの動作のプログラム速度が異なる場合には、当然、各セグメントの高さは段階的に変化したものとなる。その場合でも、補間点が作る軌跡はオーバライド率に影響されない。
【０１０９】
次に加速区間を例にとって、加減速区間における軌跡について考察する。図１６を参照すると、図の左上部に示したように、オーバライド１００％でロボットを動作させた場合の加減速部Ｂ（ここでは加速部で代表）の軌跡は、図１４に示した通りで、フィルタ部からの出力Ｄ１、Ｄ２、Ｄ３に対応する補間点ｐ１、ｐ２、ｐ３、ｐ４を通る軌跡に沿ってプログラム速度へ向かっての加速が行なわれる。
【０１１０】
オーバライド３０％でロボットを動作させた場合の加速部Ｂの軌跡は、図１５の右上部に示したように、オーバライド１００％の場合と変らない。但し、上述したオーバライドの処理（β＝３０）により、フィルタ部からの出力Ｄ１、Ｄ２、Ｄ３に対応する補間点ｐ１、ｐ２、ｐ３、ｐ４が、より多数の補間点ｐｄ１〜ｑｄ１１（符号は一部のみ表記）に変換される。各区間の計算式は図中に併記した通りである。
【０１１１】
このような性質は、オーバライド率３０％でなくとも同様に保証されている。一般には、オーバライド値１００％時の補間点を基準にして、オーバライド値に反比例する数の補間点が出力され、しかもそれらはオーバライド値１００％時の軌跡上に並ぶように形成される。
【０１１２】
図１５の左下部及び右下部には、フィルタ部出力段階の移動指令Ｄ１、Ｄ２、Ｄ３が、分割出力される様子がセグメントで表示されている。加減速部では、各セグメントの高さは段階的に変化したものとなる。この変化は、オーバライド１００％時の速度をその３０％（一般にはβ％）に減じて滑らかに加速する過程を表わしている。加速の最終到達速度は当然プログラム速度の３０％（一般にはβ％）となる。
【０１１３】
オーバライドをロボットの動作中に変更する場合には、図１７のフローチャートに示したオーバライド漸近・到達処理を行なう。この処理は後述するホールドの処理や動作再開処理でも利用される。
【０１１４】
オーバライド漸近・到達処理の各ステップの要点は次の通りである。
（ステップＬ１）；オーバライド目標値を新値βＮ に更新する。
（ステップＬ２）；オーバライド目標値の更新の次のＩＴＰからｆ回目のＩＴＰの到来を待つ。ｆは適当な大きさに設定された正整数値である。
（ステップＬ３）；オーバライド現在値をβからβ＋Δβに更新する。Δβは、例えばΔβ＝１（％）などに予め決めておくか、あるいは次式（７）で計算する。
【０１１５】
Δβ＝（βＮ −オーバライド目標値更新直前のβ）／ｎ ・・・（７）
ここで、ｎはオーバライド現在値を目標値に一致させるまでに要する更新回数で、例えばｎ＝１０などとするか、別途条件から定める（後述するホールド処理の説明を参照）。このような処理を行なうことで、図９のフローチャートにおけるβが新たな目標値に向かって段階的に変更される。
【０１１６】
［ホールドの処理］
図１０は、動的速度制御部で行なわれるホールドの処理を説明するフローチャートである。ホールドの処理は、例えばオペレータが一時停止の指令をロボット制御装置に入力した際に実行される。各ステップの要点は次の通りである。
【０１１７】
（ステップＨ１）；ホールド指令がロボット制御装置内部で出力されたか否かＩＴＰ毎にチェックする。出力されたら、ステップＨ２へ進む。
（ステップＨ２）；動的制御部にて現在の速度Ｖから、時間ｔ１経過後に滑らかに速度が０となるように、減速オーバライド値ＯＶｄを制御する。
【０１１８】
（ステップＨ３）；ロボットが停止したか否かＩＴＰ毎にチェックする。停止を確認したら、ステップＨ４へ進む。
【０１１９】
（ステップＨ４）；その時点における現在位置（停止位置）、フィルタ内の移動指令のデータ、その他ロボットの動作に関する諸データをメモリ（ホールド時格納用のレジスタ）に格納して、ホールドの処理を終了する。
ステップＨ２の処理における減速オーバライド値ＯＶｄの制御には、図１７のフローチャートに示したオーバライド漸近・到達処理を利用する。
【０１２０】
即ち、ステップＬ１におけるオーバライドの更新目標値βＮ をβＮ ＝０とする。また、時間ｔ１のＩＴＰ換算値をｓ１としてｓ１をη分割し（ηは１でない適当な正整数）、ステップＬ２におけるｆをｆ＝ｓ１／ηとする。そして、ステップＬ３におけるΔβの計算式（７）におけるｎをβＮ ＝０、ｎ＝ηで計算する。
【０１２１】
図１２は、上記のホールド処理を行なった場合の速度推移を表わしている。オーバーライドは段階的に０に向かうが、それが実際の速度に反映し切るには移動指令がサーボ系に出力され切る必要がある。そのため、速度推移は直線的には降下しない。また、動作をより滑らかにするために、Δβの値を一定値とせずに滑らかな関数（例えば指数関数）に従って徐々に変化させて滑らかな加速度推移が得られるようにしても良い。
【０１２２】
［動作再開の処理］
図１１は、動的速度制御部で行なわれる動作再開の処理を説明するフローチャートである。動作再開の処理は、一時停止後に例えば動作再開指令をロボット制御装置に入力した際に実行される。各ステップの要点は次の通りである。
【０１２３】
（ステップＨ１１）；メモリに格納した停止位置を読み出す。
（ステップＨ１２）；現在のロボット位置（例えば、ジョグ送りで移動している）からステップＨ１１で読み出された停止位置までロボットを動作させる。
（ステップＨ１３）；ステップＨ１２による動作の完了の確認。確認したら、ステップＨ１４へ進む。
（ステップＨ１４）；再開動作に必要なデータをメモリとり読み出し、動作計画部、補間部、フィルタ部へ戻し、ホールド直前の状態を回復させる。
【０１２４】
（ステップＨ１５）；停止位置から、ホールド前と同様に補間動作を行なう。また、同時に動的制御部にて現在のオーバーライド値（β＝０）から、時間ｔ２経過後に滑らかに速度が元の速度ｖとなるように、加速オーバライド値ＯＶａを制御する。
ステップＨ１５の処理における加速オーバライド値ＯＶａの制御には、図１７のフローチャートに示したオーバライド漸近・到達処理を利用する。
【０１２５】
即ち、ステップＬ１におけるオーバライドの更新目標値βＮ をβＮ ＝ホールド直前のβの値とする。また、時間ｔ２のＩＴＰ換算値をｓ２としてｓ２をη分割し（ηは１でない適当な正整数）、ステップＬ２におけるｆをｆ＝ｓ２／ηとする。そして、ステップＬ３におけるΔβの計算式（７）におけるｎをβＮ ＝ホールド直前のβの値０、ｎ＝ηで計算する。
【０１２６】
図１３は、上記のステップＨ１５の処理を行なった場合の速度推移を表わしている。オーバーライドは０から段階的に元の値に向かうが、それが実際の速度に反映し切るには移動指令がサーボ系に出力され切る必要がある。そのため、速度推移は直線的には上昇しない。また、動作をより滑らかにするために、Δβの値を一定値とせずに滑らかな関数（例えば指数関数）に従って徐々に変化させて滑らかな加速度推移が得られるようにしても良い。
【０１２７】
【発明の効果】
本発明によれば、従来技術においてオーバライドの高低、オーバライドの動作中の切換あるいは一時停止に関連して発生していた軌跡ずれが防止出来る。また、そのことを通して、教示後のテストランによる軌跡確認作業の効率性、信頼性並びに安全性を向上させることが出来る。更に、オーバライドの動作中の切換や一時停止に伴う軌跡ずれをなくなるので、ロボット作業の精度と安全性が向上する。
【図面の簡単な説明】
【図１】プログラム再生時に動作計画からサーボへの移動指令出力までにロボット制御装置内部で行なわれていた従来方式の処理の枠組みを説明する図である。
【図２】図１に示した従来方式の処理に関連して、簡単な例を用いて、軌跡ずれが発生する理由を説明するための図である。
【図３】本発明が適用されるロボット制御装置を含むロボットシステムのハードウェアの構成を例示した要部ブロック図である。
【図４】本発明の実施形態について、プログラム再生時に動作計画からサーボへの移動指令出力までにロボット制御装置内部で行なわれる処理の枠組みを図１と同様の形式で説明する図である。
【図５】オーバライドの処理をフィルタ部出力に５０％のオーバライドをかけた場合を例にとって説明する図である。
【図６】セグメントｓｇ１〜ｓｇ７で表わされる動作と、セグメントｓｋ１〜ｓｋ７で表わされる動作が、ｓｇ６、ｓｇ７とｓｋ１、ｓｋ２が同期する関係で重なり合った場合について、オーバライド処理の影響を説明する図である。
【図７】本実施形態における一時停止関連処理について説明するための図である。
【図８】本発明の実施形態について、プログラム再生時に動作計画からサーボへの移動指令出力までにロボット制御装置内部で行なわれる処理の枠組みを図４とはやや異なる形式で説明する図である。
【図９】動的速度制御部で行なわれるオーバライドの処理の要点を記したフローチャートである。
【図１０】動的速度制御部で、一時停止時に実行されるホールドの処理の要点を記したフローチャートである。
【図１１】動的速度制御部で、一時停止後の動作再開時に実行される処理の要点を記したフローチャートである。
【図１２】ホールド処理を行なった場合の速度推移を表わした図である。
【図１３】動作再開におけるオーバーライド漸増の処理を行なった場合の速度推移を表わした図である。
【図１４】図１５、図１６の説明の前提として想定される経路動作を示した図である。
【図１５】図１４に示した経路動作について、オーバライド値の高低がコーナー部における軌跡に与える影響について、オーバライド率３０％の場合を例にとって説明する図である。
【図１６】図１４に示した経路動作について、オーバライド値の高低が加減速部における軌跡に与える影響について、オーバライド率３０％の場合を例にとって説明する図である。
【図１７】オーバライド漸近・到達処理を説明するフローチャートである。
【符号の説明】
１ アーム先端部
１０ ハンド
３０ ロボット制御装置
３１ ホストＣＰＵ
３２ 共有ＲＡＭ
３３ サーボＣＰＵ
３４ サーボアンプ
３５ メモリ
３６ 教示操作盤用インターフェイス
３８ 入出力装置
３７ 教示操作盤
ＲＢ ロボット[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for controlling an industrial robot (hereinafter, simply referred to as a “robot”), and more particularly, to a robot control for improving the robot trajectory accuracy at the time of an override command or before and after a temporary stop. Equipment related.
[0002]
[Prior art]
If it is necessary to move the robot at a speed lower than the speed specified in the operation program (hereinafter referred to as “program speed”), an override that reduces the operation speed at a fixed rate to the program speed The technique is widely used. For example, for a newly created operation program or a modified operation program, a regeneration operation (test run) is performed by specifying a low-rate override, and the movement locus is checked while avoiding danger.
[0003]
The operation program whose trajectory is confirmed to be appropriate is reproduced in the control device of the robot in charge of the actual work, but the override specified during the reproduction operation naturally commands movement at the programmed speed. It is customary to set it to "100%" or a high rate close to it.
[0004]
However, when the conventional robot control device is used, there is a difference between the trajectory realized when the moving speed is reduced by the override and the trajectory realized when the override is specified at 100% (no speed reduction). Was. This trajectory shift has the property of increasing as the designated override value decreases. In other words, if the robot approaches a corner during operation under a low-rate override, the position of the tool tip point in any axis, straight line, or circular motion, except when positioning is performed at that corner. The trajectory changed greatly depending on the specified override value.
[0005]
For this reason, in the actual trajectory confirmation, an attempt is made to confirm an accurate trajectory by starting from an operation in which a low-rate override is designated and repeating a test run while gradually increasing the override. Such a trajectory shift occurs in a similar manner not only when a low-rate override is designated, but also when an override value is changed during operation or before and after a temporary stop (at the time of deceleration or acceleration) of the robot.
[0006]
After all, in the prior art, it took a long time to repeat the test run from the position teaching until the operation was performed at the override of 100%. When a pause process is performed during the program reproducing operation, the position of the tool tip point along with the deceleration is changed to the locus of the tool tip point drawn during normal work without performing the pause process (hereinafter, “normal locus”). ) And stops at a position that is not normally on the trajectory. In this specification, "temporary stop" does not include "emergency stop" which means that the movement command output to the servo is instantaneously stopped by an alarm output.
[0007]
Similarly, the trajectory of the tool tip point immediately after resuming the program reproduction after the pause is also out of the normal trajectory, and requires a considerable moving distance until it coincides with the normal trajectory. Such a shift in the trajectory has also caused interference between an end effector such as a robot hand and an external object (a jig, a work, another installed device, etc.).
[0008]
FIG. 1 is a diagram for explaining a framework of a conventional processing that is performed inside a robot controller from an operation plan to a movement command output to a servo during program reproduction in order to consider the above-described problem. The framework of normal processing according to the conventional method is as shown in FIG. 1, and the entire framework is roughly divided into an operation planning unit, an interpolation processing unit, and a filter unit, and each unit is a sequence for each axis operation. The sequence can be divided into two for orthogonal operation (linear operation, arc operation, etc.).
[0009]
The motion planning unit is a part that creates a robot motion plan according to the contents specified in the motion program (moving target position, motion format, program speed, etc.). If the motion format specified in the motion program is each axis motion, An operation plan is created by the operation planning unit, and if the motion format specified by the operation program is orthogonal operation (linear operation, arc operation, etc.), the operation plan is created by the orthogonal operation planning unit.
[0010]
The override is considered by the operation planning unit, and the product of the program speed and the override (percentage) is the commanded far output to the interpolation processing unit. Between the operation planning unit and the interpolation processing unit, there is provided a block functioning as an operation shutter for controlling sending of the command speed output from the operation planning unit to the interpolation processing unit. The operation shutter is opened each time the commanded far output is generated, and passes the command far output to the interpolation processing unit.
[0011]
In response to the command output, the interpolation processing unit performs an interpolation process on each axis or a rectangular coordinate system at each calculation processing cycle (ITP), and calculates and outputs a movement amount for each ITP. In the subsequent filter unit, the output of the interpolation processing unit is filtered with a predetermined time constant. This process is performed to control the acceleration / deceleration of the robot and to smooth the acceleration / deceleration movement.
[0012]
The output filtered by each axis filter processing unit is also output to the servo of each axis (J1 to J6) after filtering. In the case of the orthogonal operation, a so-called inverse conversion process for performing conversion from the orthogonal coordinate system to each axis coordinate system is required. In the inverse conversion process, the inverse conversion is often performed before the filtering, but may be performed after the filtering.
[0013]
If a temporary stop command is output inside the robot controller during the reproduction operation, the interpolation processing unit is held by the inversion of the operation shutter and the interrogation processing is interrupted. The output created by the interpolation process before the hold command is issued is filtered by the filter unit and then output to the servo. When the movement command output to the servo is consumed by the movement of each axis, the input to the servo is interrupted, and the robot stops.
[0014]
When a path that smoothly connects the two operations is specified by the operation program, the two operation commands are processed in a superimposed manner. At this time, if the moving tangent direction at the end point of the preceding operation of the two operations is different from the moving tangent direction at the start point of the following operation, a rounded corner is generated. The overlapping amount of the motion at this time determines the inner shape of the corner.
[0015]
Here, the relationship between the level of the override and the overlap amount of the operation will be considered. When the override is low, the command speed naturally decreases, but the time constant of the acceleration / deceleration processing of the filter does not change, so that the overlap amount of the operation decreases. This means that the inward turning amount of the corner becomes smaller (that is, the curvature of the roundness becomes smaller). Conversely, when the override is high, the command speed naturally increases, and the overlap amount of the operation increases under the time constant of the acceleration / deceleration processing of the same filter. As a result, the inward turning amount of the corner increases (that is, the curvature of the roundness increases).
[0016]
FIG. 2 is a diagram illustrating these phenomena in a simple example. In the example of FIG. 2, the operation program includes an operation of linearly moving at 2000 mm / sec toward point [1] and an operation of linearly moving and stopping (positioning) at 1000 mm / sec toward point [2]. Think of something that connects with a% smoothness. In order to consider the phenomenon associated with the corner passing, as shown in the figure, it is assumed that the straight path toward the point [1] is in the −X axis direction, and the straight path toward the point [2] is in the + Y axis direction. The transition of the command speed output after the filtering process for each operation is also shown in the upper right part, and the symbols a and b generally indicate the overlap of the operations.
[0017]
Now, assuming that the high override is 100% and the low override is 50%, the overlaps a1 and b1 after the filter processing when the override is 100% and the overlaps a2 and b2 after the filter processing when the override is 50% are respectively. The result is as shown in the figure. That is, although the override is different by a factor of two, filtering is performed with the same time constant, so that there is a large difference in the amount of overlapping operation. As a result, the trajectories realized are different as indicated by c1 and c2. The roundness of the corner is large at c1 and small at c2.
[0018]
Next, in the case of the override of 100%, a case is considered in which a hold is applied due to a temporary stop at a point P during a corner passing represented by the point [1]. From the time when the hold is applied, the output of the interpolation processing unit for the operation toward the position [2] is sharply reduced as compared with the case where the hold is not applied (indicated by a broken line d), and only the residual command output is output. For this reason, an overlap between the two operations after the filtering process has an effect of rapidly decreasing during the movement of the corner.
[0019]
As a result, the trajectory shifts from the point P corresponding to the time when the hold was applied to the corner representative point 1 [2] side, as shown by c3, and stops at the point Q deviated from the trajectory c1 when the hold was not applied. (Note that the operation toward [1] is digested). When the reproduction is resumed after the pause, the robot trajectory follows the trajectory indicated by c4 from point Q (coincident with c1 from the middle).
[0020]
It is clear that a similar trajectory shift phenomenon also occurs when the override is switched during cornering. This is because the filtering is performed under the same time constant, so that the amount of overlap between the two operations changes depending on the magnitude of the output of the interpolation processing unit, and as a result, the trajectory changes.
[0021]
That is, in the various cases in which the trajectory shift occurs (override level, switching during the operation of the override, before and after the temporary stop), a common factor that the transition of the input level of the filtering processing is different from the normal state is as follows. is there. Since the filtering process is performed under the same time constant even though the input level of the filtering process is changed, it can be considered that a difference occurs in the operation path in a portion where different operations in two directions overlap. .
[0022]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to provide a robot control device that can eliminate a trajectory shift generated by the common factor in the related art. That is, an object of the present invention is to provide a robot control device capable of preventing a decrease in trajectory accuracy before and after a change in override operation, a change during override operation, and a temporary stop.
[0023]
The present invention also intends to eliminate the deviation between the trajectory during the test run after the teaching and the trajectory during the operation under the high override, thereby improving the efficiency and safety of the trajectory checking work. is there. Further, the present invention aims to improve the accuracy and safety of the robot operation by eliminating the trajectory shift due to the switching or the temporary stop during the operation of the override.
[0024]
[Means for Solving the Problems]
The present invention provides a robot control device equipped with software capable of eliminating a trajectory shift generated due to the above-described factors, and a software for outputting a movement command to a servo system of a servo motor that drives each axis of the robot. The present invention is applied to a robot control device having means.
[0025]
According to the present invention, the software means provided in the robot control device obtains the movement amount of the robot to the operation target position, interpolates this in a certain cycle, and uses the interpolated output for acceleration / deceleration control. And a dynamic speed control unit that receives the movement command after the filtering process as input, and corrects the movement command according to a designated command override value common to each axis.
[0026]
And the dynamic speed control means,When the command override value is β% (0 ≦ β ≦ 100),In response to the movement command, the speed is(Β / 100) times and acceleration is (β / 100) ² Movement command that doubles (move command after override processing)Output means.
[0027]
Here, the robot control device according to the present invention smoothly changes the command override value for the dynamic speed control means from the current override value to the target override value when the target override value is different from the current override value. Command override calculating means for causing the command to be calculated.
[0028]
Further, the robot control device according to the present invention sets the target override value to 0 when the robot is temporarily stopped at the time of executing the program, and sets the target override value to the dynamic speed control unit by the command override calculation unit. Is smoothly changed from the current override value to 0 to decelerate and stop the robot.
[0029]
Further, the robot control device according to the present invention sets both the target override value and the command override value to 0 and sets the movement command output to 0 instantaneously when stopping the robot in an emergency when executing the program. It can be configured to stop immediately.
[0030]
On the other hand, in the case where the robot is temporarily stopped during the execution of the program ram, or after an emergency stop, the operation is resumed after the stop, the robot control device according to the present invention uses the command override calculating means to set the command override value. The robot can be configured to accelerate by smoothly changing from 0 to the target override value.
[0031]
Further, by using the command override calculation means, the command override value for the dynamic speed control means can be changed stepwise by dividing the current override value to the target override value into a specified number of divisions.
[0032]
Here, regarding changing the command override value for the dynamic speed control means using the command override calculation means, a smooth change using an exponential function from the current override value to the target override value is realized. You may do it.
[0033]
Further, the operation data may be stored in the robot controller near the time of the temporary stop, and the stored operation data may be used when the operation is resumed.
[0034]
In the present invention, the operation plan based on the operation program may include an orthogonal operation plan for performing an orthogonal operation on at least one operation section. Further, the operation plan based on the operation program may include each axis operation plan for performing each axis operation for at least one operation section.
[0035]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 3 is a main block diagram illustrating the hardware configuration of a robot system including a robot control device to which the present invention is applied. As shown in the figure, the robot control device generally designated by reference numeral 30 controls a robot RB in which the hand 10 is attached to the arm tip 1 as an end effector. Here, the robot RB is a six-axis robot. The tool tip point TCP, which is a point representing the position of the end effector (hand 10), is set at the center of the hand 10.
[0036]
The robot controller 30 includes a host CPU 31, a shared RAM 32, a servo CPU 33, a servo amplifier 34, a memory 35, a teaching operation panel interface 36, and an input / output device 38 for a general external device. The memory 35 includes a ROM in which a system program is stored, a RAM for temporarily storing data, and a system (a non-volatile memory in which various program data defining the operation of the robot RB are stored).
[0037]
The teaching operation panel 37 connected to the teaching operation panel interface 36 is used for inputting, correcting, and registering program data, and for manual input of a manual feed ((jog feed) command, a regeneration operation command, etc.). In addition to the mechanical brake of the robot RB, various external devices (for example, a power supply device for welding) corresponding to the application are connected to the device input / output device 38.
[0038]
At the time of executing the regeneration operation or the manual feed (jog feed), the host CPU 31 creates a movement command for each axis of the robot RB and outputs it to the shared RAM 32. The servo CPU 33 reads this out at a predetermined short cycle, executes servo processing based on a position signal (feedback) sent from a position detector (pulse coder) of each axis of the robot, and supplies a current command to the servo amplifier 34 of each axis. And drives the servo motors of each axis of the robot. The servo CPU 33 periodically writes the current position of each axis of the robot to the shared RAM 32 based on a position signal (feedback) sent from a position detector (pulse coder) of each axis of the robot.
[0039]
The configuration and function described above are not particularly different from those of a normal robot system. The robot controller 30 used in the present system is different from the conventional one in that the processing steps from the host CPU 31 reading the program data to creating a movement command for each axis of the robot RB are improved. This is to prevent the robot's trajectory deviation occurring due to the various factors (override level, switching during override operation, processing before and after temporary stop). The improved program data and related setting values are stored in the memory 35. The following description focuses on this improvement.
[0040]
FIG. 4 is a diagram illustrating, in the same form as that of FIG. 1, a framework of processing performed within the robot controller from the operation plan to the movement command output to the servo during program reproduction according to the embodiment of the present invention.
[0041]
The entire processing framework shown in FIG. 4 includes an operation planning unit, an interpolation processing unit, and a filter unit, each of which has a block for each axis operation and a block for orthogonal operation, as in the related art. Can be divided into a series for each axis operation and a series for orthogonal operation (linear operation, arc operation, etc.).
[0042]
The motion planning unit is a part that creates a robot motion plan according to the contents specified in the motion program (moving target position, motion format, program speed, etc.). If the motion format specified in the motion program is each axis motion, An operation plan is created by the operation planning unit, and if the motion format specified by the operation program is orthogonal operation (linear operation, arc operation, etc.), the operation plan is created by the orthogonal operation planning unit.
[0043]
In the interpolation processing unit, upon receiving the command distance output, the interpolation processing is performed on each axis or the orthogonal coordinate system at every predetermined calculation processing cycle (ITP), and the movement amount for each ITP is calculated and output. . In the subsequent filter unit, the output of the interpolation processing unit is filtered with a predetermined time constant for acceleration / deceleration control. The output from each axis interpolation processing unit is filtered by each axis filter processing unit.
[0044]
Although the above block configuration is common to the conventional one, the step of considering the override is basically different from the conventional one. That is, as described above, in the conventional processing, the override is considered in the processing of the operation plan, and the output after being multiplied by the override value is passed to the interpolation processing unit via the operation shutter. In the present embodiment, according to the features of the present invention, it is provided at the subsequent stage of the filter unit.
[0045]
In addition, the block of the operation shutter is also moved to the subsequent stage of the filter unit.
[0046]
The override is considered in the override processing unit with the operation shutter (also referred to as a dynamic speed control unit; the same applies to the following). The output of the filter unit multiplied by the override (percentage) is calculated for each axis (J1 to J6). Are distributed and output to the servos. The output from the orthogonal interpolation processing unit is filtered by the orthogonal filter processing unit, subjected to inverse transformation, and distributed and output to servos of each axis (J1 to J6). The output from the orthogonal interpolation processing unit is subjected to an inverse conversion process at the time of distribution to each axis.
[0047]
If a temporary stop command is output inside the robot controller during the reproduction operation, the hold is applied not to the interpolation processing unit but to the override unit (the output of the filter unit) by the inversion of the operation shutter.
[0048]
The processing that characterizes the present embodiment is divided into override-related processing and temporary stop-related processing, and the outline thereof is as follows.
[0049]
(1) Overview of override-related processing;
In the present embodiment, as shown in the lower half of FIG. 4, the motion planning unit does not consider the override, and performs the interpolation processing on the input at the program speed. The output after the interpolation processing is filtered by a subsequent filter unit under a predetermined time constant. At this stage, it is clear that there is no room for the process to depend on the override. Therefore, whether the override is high or low, or if the override rate is switched during the operation, the output of the filter unit is not affected at all.
[0050]
In the following override processing, the output of the filter unit is modified so as to satisfy the following conditional expressions (1) and (2). Note that the override value is represented by β% (0 ≦ β ≦ 100), the velocity represented by the output of the filter unit is represented by vfout acceleration, αfout represents the velocity represented by the output after the override processing is represented by vovout, and the acceleration is represented by αovout.
[0051]
αovout = αflow × (β / 100) 2 (1)
vovout = vfout × (β / 100) (2)
FIG. 5 is a diagram illustrating an example of a case where an override process is applied to a filter unit output by 50%. In the override processing, an instruction is divided and an output is generated while synchronizing all axes. If the output of the filter unit is represented by seven segments sg1 to sg7 (seven movement commands), the segments sg1, sg2,... Sg7 are divided into a total of 15 segments using 15ITP. Is output.
[0052]
For example, sg1 is output in half at sh2, and is output at １ ／ each of sh1 and sh3. Also, sg4 is output in half at sh8, and is output at quarters at sh7 and sh9. Except for both ends, each segment sh at the time of output generally has a movement amount derived from the segment sg of a plurality of filter unit outputs overlapping. Now, when the movement amounts corresponding to sg1, sg2, and sg3 are represented by vectors m1, m2, and m3, the output segmants sh1 to sh5 derived from the movement amounts are represented by vectors n1 to n5 as illustrated. Will represent a quantity. As the route, a locus with increased smoothness is obtained as the override is lower, but the basic line of the locus does not change before and after the override process.
[0053]
The formula for calculating the amount of movement for each ITP in the override processing (output segment = amount of movement per ITP, corresponding to the instantaneous speed value) will be described later, but the main points are as follows.
[0054]
1-1. A movement amount is calculated by multiplying each movement amount (input segment) of the output of the filter unit that has undergone the acceleration / deceleration processing by the override rate (β / 100).
[0055]
1-2. 1-1. If the amount of movement calculated in (1) is too large (if the output is performed as it is, the left side of the above equations (1) and (2) becomes too large to satisfy the equation), the excess is subtracted and output. I do. In the first ITP, the above 1-1. With the movement amount calculated in (1), there is no case where the movement amount is too small to satisfy Expressions (1) and (2) (because β ≦ 100, the left side of Expressions (1) and (2) is too small). Never be.)
[0056]
2. In the next ITP, the movement amount is calculated by multiplying the non-output movement amount again by the override rate (β / 100). However, if the amount of movement is insufficient (if the above equations (1) and (2) cannot be satisfied), the shortage is added and output. Insufficient outputs are selected with priority given to unoutputted old movement commands (input segments). In the second and subsequent ITPs, the above-described calculation of multiplying the non-output movement amount by the override rate (β / 100) again does not make the movement amount excessive.
[0057]
3. Further, in the next ITP, for a movement command having a movement amount that has not been output, a movement multiplied again by the override rate (β / 100) is output. If the amount of movement is insufficient (if the above equations (1) and (2) cannot be satisfied), the shortage is added and output. Insufficient outputs are selected with priority given to unoutputted old movement commands (input segments). Hereinafter, the same processing is repeated, and when the entire movement amount of all the movement commands is output, the processing is ended.
[0058]
In such processing, the movement amount used for acceleration, the movement amount of the acceleration unit, and the movement amount of the deceleration unit become substantially constant. This means that even when the override changes, the overlap amount when the two operations overlap is constant. Therefore, regardless of the level of the override, a substantially constant locus is realized even when the vehicle passes through the corner.
[0059]
FIG. 6 is a diagram for explaining the effect of the override process when the operations represented by the segments sg1 to sg7 and the operations represented by the segments sk1 to sk7 overlap in a synchronous relationship between sg6 and sg7 and sk1 and sk2. is there. Now, assuming an example of an override of 50%, the segments sg1 to sg7 are divided into sh1 to sh15 and output as described with reference to FIG. At this time, the moving amount represented by sg6 is distributed to sh11, sh12, and sh13, and the moving amount represented by sg7 is distributed to sh13, sh14, and sh15.
[0060]
Similarly, the segments sk1 to sk7 are also divided into sk1 to sk15 and output. The moving amount represented by sk1 is distributed to sq1, sq2, and sq3, and the moving amount represented by sk2 is distributed to sq3, sq4, and sq5. When viewed after the override processing, the two operations overlap at sh11 to sh15 and sq1 to sq7.
[0061]
As described above, the digestion speed of the movement amount at the time of the overlap of the movements is reduced equally for both operations (here, half), and the total movement amount to be digested is not changed by the 50% override processing. Such a property does not change even if the override rate is other values.
[0062]
Even when the override is switched during the operation, a constant locus can be similarly maintained by smoothly changing the division ratio of the segment of the filter output and performing the override processing according to the above example.
[0063]
In this case, the new and old override rates are (βN / 100) and (βO / 100), and the acceleration is changed halfway from (βN / 100) 2 to (βO / 100) 2. Therefore, the output of the override processing, which was scheduled to be output by the ITP immediately after the override change command, is adjusted and output so as to be further divided into 1 / [βN / (βO × 100)] times.
[0064]
In order to avoid the influence of the sudden change of the new and old override rates (βN / 100) and (βO / 100), it is preferable to smoothly change the override rate stepwise from (βN / 100) to (βO / 100). . Therefore, in practice, a register for setting the target override value is set in the memory, and the user updates and inputs the new override value βN to this register, thereby changing the current override value to the target override value (here, Then, the process of asymptotically reaching the new override rate βN) is started.
[0065]
In calculating the movement amount in each ITP, n times (n The movement amount is calculated using the values divided into ≧ 2). For example, in the j-th ITP immediately after the update of the override target value, β = βO + jΔβ. Where Δβ = (βN−βO)
/ N, j = 1, 2,... N.
[0066]
(2) Summary of suspension-related processing;
FIG. 7 is a diagram for describing the temporary stop related processing in the present embodiment. Here, as an example, the output of the filter unit represented by the segments sg1 to sg18 (the output after the override processing may be performed) to the servo up to the segment sg4 is completed, and the output of the segment sg5 is completed. Consider a case where a hold command is internally output by the ITP.
[0067]
In this case, as shown in the figure, the data representing the movement amount after the segment sg5 is not output to the servo as it is, but is stored in a predetermined memory (a buffer preset in the memory 35 in FIG. 3). Once stored. However, the segments sg5, sg6, and sg7 corresponding to a predetermined time constant (here, 3ITP) are dynamically processed by the override processing unit, and each axis is decelerated and eventually stopped.
As the dynamic processing for deceleration / stop, the override target value is set to 0 by applying the above-described method of applying the override, and gradually reduced to 0, which is the override target value, n times (n ≧ 2). Can be adopted.
[0068]
In the illustrated example, the segments sg5, sg6, and sg7 are distributed to sw5 to sw9. Eventually, sw5 to sw9 are output to the servo following segments sg1 to sg4 (before holding), and the robot stops when the movement represented by these segments is completed. It should be noted here that the total movement amount digested by sw5 to sw9 representing the deceleration process is smaller than the total movement amount represented by the segments sg5, sg6, and sg7.
[0069]
The surplus movement amount is consumed during the acceleration process when the pause is released and the operation is resumed. That is, when the suspension is released, data representing the movement amount after the segment sg5 is read from the memory and output to the servo while accelerating to the original command speed.
[0070]
In the acceleration process, a value obtained by subtracting sw5 to sw9 digested in the deceleration process from the total movement amount represented by the segments sg5, sg6, and sg7 is digested. For this purpose, by applying the above-described method of applying the override, a process of setting the override target value to the override value before suspension (for example, 100) and gradually increasing the override target value to the override target value in n times can be adopted.
As the dynamic processing, a processing corresponding to gradually increasing the override to 100% in n times (n ≧ 2) by applying the above-described method of applying the override can be adopted.
[0071]
After all, when the operation is resumed, sw10 to sw15 are output to the servo, and then sg8 and thereafter are output. The total movement amount digested by the segments sw5 to sw15 representing the deceleration process and the acceleration process is equal to the total movement amount represented by the segments sg5, sg6, and sg7.
[0072]
By performing such processing before and after the temporary stop, the robot decelerates and stops while maintaining the trajectory when the hold command is output, and accelerates the robot while maintaining the trajectory from there when restarting. It can be shifted to operation.
[0073]
At the time of the hold, it goes without saying that the operation plan data at the time of deceleration stop, the interpolation data, the filter data, and the like are frozen and stored as they are in preparation for the restart of the operation. At the time of the resuming operation, the operation is started from a state where the override is set to 0, and the data stored at the time of the hold is restored. Thereafter, the override is gradually increased while smoothly synchronizing all axes again. As a result, it is possible to perform deceleration stop and restart operations by changing the override while synchronizing all axes while performing processing as if there was no hold up to the operation planning unit, interpolation unit, and filter unit. Will be possible.
[0074]
When performing an emergency stop by an alarm, the output to the servo is immediately stopped without using the above-mentioned temporary stop method as it is, and the robot is stopped as soon as possible. In the example of FIG. 6, sw6 to sw9 forming the deceleration process are not output to the servo.
[0075]
In this case, since the trajectory is deviated due to the emergency stop, the trajectory may return to the original trajectory at a low rate of override (temporary positioning), and then accelerated by applying the above-described override change method. Data for calculating the amount of movement required to return to the original trajectory (in the example of FIG. 6, data of sw6 to sw9 which have not been output to the servo segment due to an emergency stop), data of program speed, etc. Is stored in the memory near the point of emergency stop. Further, various data for determining the operation after returning to the original trajectory are also stored in the memory near the point of emergency stop.
[0076]
The above is the outline of the embodiment. In the following, the processing of the dynamic speed control executed to avoid the trajectory deviation of the robot will be described in more detail by dividing it into an override processing and a pause / operation restart processing. In the description, a case of an override rate of 30% (β = 30) is considered as an example of an override rate different from the override rate of 50% (β = 50).
[0077]
FIG. 8 is a diagram illustrating, in a form slightly different from FIG. 4, a framework of processing performed in the robot controller from the operation plan to the movement command output to the servo during program reproduction, according to the embodiment of the present invention. In this drawing, while the division of the series for each axis operation and the series for orthogonal operation (linear operation, arc operation, etc.) is omitted, the override processing unit with a dynamic shutter is described as a dynamic speed control unit, The memory used in connection with dynamic speed control has been simplified and added to the block display.
[0078]
Referring to FIG. 8, the entire system includes an operation planning unit, an interpolation processing unit, a filter unit, and a dynamic speed control unit, and the output of the dynamic speed control unit is a servo system of each axis (displayed as a motor). Passed to In the processing flow, a memory is interposed on the input side and the output side of the dynamic speed control unit. A large number of register areas are prepared in the memory in advance so as to conform to the processing described below.
[0079]
Each register area is also simply called a memory. Also, the n-th movement command after the filtering process output from the filter unit is denoted by Dn. In the drawing, it is described that the movement command Dn is stored in the memory Mn on the input side of the dynamic speed control unit. Each block described in a vertical line means one unit of memory (buffer register area). It is illustrated that D1 is stored in the input memory M1, D2 is stored in M2, and Dn (n = 1, 2) is stored in Mn.
[0080]
Further, it is described that D2, D2 ', D1, and D1' are stored in the output memories O1 to O4 of the dynamic speed control unit, respectively. Here, D2 'and D1' are values obtained by multiplying D1 and D2 by an override value (β / 100). Details of how to use the input side and output side memories will be described in the following processing description.
[0081]
[Override processing]
FIG. 9 is a flowchart illustrating an override process performed by the dynamic speed control unit. The main points of each step are as follows. Note that i is a labeling index of the interpolation cycle, and the initial value is i = 1. A register for setting a current value β and a target value γ of the override is prepared, and a desired override target value γ0 is set in advance for the latter. As the initial value of the current value β of the override, a value that matches the initially set target value γ0 is automatically set.
[0082]
(Step S1): It is checked whether or not the movement commands Di and Di + 1 are stored in the memories M1 and M2, respectively. If not stored, the process proceeds to step S2, and if stored, the process proceeds to step S3.
[0083]
(Step S2): The movement commands Di and Di + 1 are stored in the memories M1 and M2, respectively, and are set as the movement commands Dm1 and Dm2. Here, m1 and m2 are labels indicating that they are data stored in the memories M1 and M2, respectively.
[0084]
(Step S3): It is checked whether the value of the movement command Mm1 stored in the memory M1 is 0. If yes, go to step S4; if no, go to step S5.
[0085]
(Step S4): The movement command Dm2 stored in the memory M2 is copied to the memory M1 and set as Dm1 (update of the value of the movement command Dm1). Then, the dynamic command Di + 2 next to Di + 1 is read, stored in the memory M2, and set as Dm2 (update of the value of Dm2).
[0086]
(Step S5); A current value β% of the override is determined, and a movement amount Di per interpolation (per ITP) (the height of a segment representing the movement amount) Di is calculated under the determined β value. The method of calculating Di will be described later. The current override value β may change during operation if the target value γ changes. The value of β changes during the operation, for example, at the time of a user input, change by an external signal, temporary stop (hold), temporary stop (hold), or restart of operation after an emergency stop. The process of determining the current value β% of the override will be described later together with the process of temporarily stopping (holding) and subsequently resuming operation.
[0087]
(Step S6): The Di calculated in Step S5 is compared with the movement command Dm1 stored in the memory M1. If Dm1-Di> 0, the process proceeds to step S8; otherwise (Dm1-Di ≧ 0), the process proceeds to step S7.
[0088]
(Step S7): The movement command Dm1 stored in the memory M1 is copied to the memory O1 on the output side. Next, using these Dm1 and Dm2,
Di = Dm1 + Dm2 * μ
Is obtained. Then, from this μ, Di ′ satisfying Di ′ = Dm2 * μ is added to the output memory O1. Further, Dm2 is updated to Dm2 = Dm2−Dm2 * μ, which is copied to the memory M1 to obtain a new Dm1 (update of Dm1).
[0089]
(Step S8): The movement command Di determined in Step S5 is written to the output side memory O1. Further, the movement command Dm1 stored in the memory M1 is updated to a new Dm1 = Dm1-Di.
[0090]
(Step S9): The movement command Do of the output side memory is output to the motor (each axis servo system).
[0091]
(Step S10); A command for stopping the robot, such as hold, temporary stop, emergency stop, operation end command (issued when a new Di output is not from the filter unit and the process of Step S2 cannot be performed), etc. Check whether the signal is output inside the controller. If yes, the process for them (described later) is executed to stop the robot.
If no, the process proceeds to step S11.
[0092]
(Step S11); 1 is added to the index value i of the movement command, and the process returns to step S1.
[0093]
Here, a method of calculating the movement amount Di 'per interpolation (per ITP) when the override (current value) in step S5 is?% Will be described.
[0094]
The following formula is used to calculate the movement amount Di 'so that the speed change can be smoothly obtained even when the movement command Di output from the filter unit is not constant.
[0095]
The movement command Di 'per i-th one interpolation time (ITP) t0 is represented by the following equation (3).
[0096]
Di '= V (i) * t0 (3)
Here, V (i) is the speed when the override in the i-th ITP is 100%. The acceleration A (i) per ITP when the override in the i-th ITP is set to 100% is temporarily expressed by the following equation (4).
[0097]
A (i) = V (i) -V (i-1) (4)
Using this A (i) to smooth the speed transition, the following equation (5) is adopted as a reference equation of the acceleration output at the i-th ITP at present.
[0098]
Aout (i) = − A (i−1) / 2 + 3 * A (i) / 2 (5)
Using this, the following equation (6) is adopted as the speed output at the i-th ITP at present.
[0099]

Here, OVR = β / 100, δ becomes δ = 1 when the output of V (i) is fully output to the servo system, and δ = when the output of V (i) is not fully output to the servo system. It becomes 0.
[0100]
For example, if the override is 100%,
When Vout (i) = 1 * [V (i) + Aout (i) * (0 + 1 / 2−1 / 2) = V (i), a natural result is obtained. In the case of 50% override,
Vout (i) = 0.5 * [V (i) + Aout (i) * (δ + 0.5 / 2−1 / 2) = V (i) / 2 + Aout (i) / 2 * (δ− ／)
And
When δ = 1; V (i) / 2−Aout (i) / 8
When δ = 0; V (i) / 2 + Aout (i) / 8
It becomes.
[0101]
The effect of the level of the override value on the trajectory when the path operation including the corner portion is performed while performing the above-described processing will be described with reference to FIGS. 15 and 16 using an example of an override rate of 30%. . As a path operation including a corner portion, as shown in FIG. 14, a linear operation from the position G1 to the position G2 and a linear operation from the position G2 to the position G3 are smoothly connected. The program speeds of both operations are assumed to be equal.
[0102]
The crosses indicate the teaching points G1, G2, G3, and the crosses indicate the position (interpolation position) of the interpolation point corresponding to the movement command finally output to the servo system. The corners are indicated by the symbol A. On the other hand, the range B represents a section of acceleration for starting and a section of deceleration for stopping (positioning).
[0103]
In the case of this example, at the corner portion A, the marks are arranged at regular intervals, and in the acceleration / deceleration section B, the intervals of the marks are gradually enlarged or reduced. Symbols q1, q2, and q3 are interpolation points representing trajectories in the corner portion A, and form a movement section corresponding to the outputs D1 and D2 from the filter portion in the corner portion.
[0104]
Symbols p1, p2, p3, and p4 are interpolation points representing trajectories in the acceleration section B, and form moving sections corresponding to outputs D1 and D2 from the filter section in the acceleration / deceleration section. Although the number of interpolation points (★ marks) actually generated is much larger, the number is simply illustrated in a small number for display.
[0105]
Referring to FIG. 15, as shown in the upper left part of the figure, the locus of the corner A when the robot is operated with the override of 100% is as shown in FIG. 14, and the outputs D1 and D2 from the filter are as shown in FIG. Are obtained through the interpolation points q1, q2, q3 corresponding to.
[0106]
On the other hand, the locus of the corner A when the robot is operated with the override of 30% is as shown in the upper right part of FIG. By the above-described override processing (β = 30), the interpolation points q1, q2, and q3 corresponding to the outputs D1 and D2 from the filter unit are converted into a larger number of interpolation points qd1 to qd9 (signs are partially shown). Is done. The calculation formula for each section is as shown in the figure.
[0107]
What is important here is that these interpolation points qd1 to qd9 are on the trajectory when the original override is 100%. This property is similarly guaranteed even if the override rate is not 30%. In general, a number of interpolation points that are inversely proportional to the override value are output on the basis of the interpolation point when the override value is 100%, and are formed so as to be arranged on the locus when the override value is 100%. Therefore, the same trajectory can be obtained even at the corner portion regardless of the level of the override value.
[0108]
In the lower left and lower right portions of FIG. 15, the state in which the movement commands D1 and D2 at the filter unit output stage are divided and output is displayed in segments. When the vehicle passes through the corner at a constant speed as in this example, the height of each segment is constant. If the program speeds of the two operations for forming the corner portion are different, the height of each segment naturally changes stepwise. Even in such a case, the trajectory created by the interpolation points is not affected by the override rate.
[0109]
Next, taking the acceleration section as an example, the trajectory in the acceleration / deceleration section will be considered. Referring to FIG. 16, as shown in the upper left part of the figure, the trajectory of the acceleration / deceleration unit B (represented by the acceleration unit here) when the robot is operated with the override of 100% is as shown in FIG. 14. The acceleration toward the program speed is performed along a locus passing through the interpolation points p1, p2, p3, and p4 corresponding to the outputs D1, D2, and D3 from the filter unit.
[0110]
The trajectory of the acceleration unit B when the robot is operated with the override of 30% is not different from the case of the override of 100% as shown in the upper right part of FIG. However, by the above-described override processing (β = 30), the interpolation points p1, p2, p3, and p4 corresponding to the outputs D1, D2, and D3 from the filter unit are changed to a larger number of interpolation points pd1 to qd11 (the sign is one. Part only). The calculation formula for each section is as shown in the figure.
[0111]
Such a property is similarly guaranteed even if the override rate is not 30%. In general, a number of interpolation points that are inversely proportional to the override value are output on the basis of the interpolation point when the override value is 100%, and are formed so as to be arranged on the locus when the override value is 100%.
[0112]
In the lower left and lower right portions of FIG. 15, the manner in which the movement commands D1, D2, and D3 in the filter unit output stage are divided and output is displayed in segments. In the acceleration / deceleration section, the height of each segment changes stepwise. This change represents a process in which the speed at the time of 100% override is reduced to 30% (generally, β%) to accelerate smoothly. The final reaching speed of acceleration is naturally 30% (generally β%) of the program speed.
[0113]
When the override is changed during the operation of the robot, the override asymptotic / arrival processing shown in the flowchart of FIG. 17 is performed. This process is also used in a hold process and an operation restart process described later.
[0114]
The main points of each step of the override asymptotic / arrival processing are as follows.
(Step L1); The override target value is updated to the new value βN.
(Step L2); Wait for the fth ITP from the next ITP after the update of the override target value. f is a positive integer value set to an appropriate size.
(Step L3); Update the override current value from β to β + Δβ. Δβ is determined in advance, for example, as Δβ = 1 (%), or calculated by the following equation (7).
[0115]
Δβ = (βN−β just before updating the override target value) / n (7)
Here, n is the number of updates required until the current override value matches the target value, and is set to, for example, n = 10, or separately determined from a condition (see the description of the hold processing described later). By performing such processing, β in the flowchart of FIG. 9 is changed stepwise toward a new target value.
[0116]
[Hold processing]
FIG. 10 is a flowchart illustrating a hold process performed by the dynamic speed control unit. The hold processing is executed, for example, when the operator inputs a temporary stop command to the robot controller. The main points of each step are as follows.
[0117]
(Step H1); It is checked for each ITP whether a hold command has been output inside the robot controller. If output, the process proceeds to step H2.
(Step H2): The dynamic control unit controls the deceleration override value OVd from the current speed V so that the speed smoothly becomes 0 after the time t1 has elapsed.
[0118]
(Step H3): It is checked for each ITP whether or not the robot has stopped. After confirming the stop, the process proceeds to step H4.
[0119]
(Step H4): The current position (stop position) at that time, the data of the movement command in the filter, and other data related to the operation of the robot are stored in a memory (a register for storing at the time of holding), and the holding process is completed. I do.
For the control of the deceleration override value OVd in the process of step H2, the override asymptotic / arrival process shown in the flowchart of FIG. 17 is used.
[0120]
That is, the update target value βN of the override in step L1 is set to βN = 0. Further, s1 is divided by η (η is an appropriate positive integer other than 1) with the ITP conversion value of time t1 as s1, and f in step L2 is set to f = s1 / η. Then, n in the equation (7) for calculating Δβ in step L3 is calculated using βN = 0 and n = η.
[0121]
FIG. 12 shows a change in speed when the above-described hold processing is performed. The override gradually goes to 0, but the movement command needs to be completely output to the servo system in order to fully reflect the actual speed. Therefore, the speed transition does not drop linearly. Further, in order to make the operation smoother, the value of Δβ may not be a fixed value but may be gradually changed according to a smooth function (for example, an exponential function) to obtain a smooth transition of acceleration.
[0122]
[Operation restart processing]
FIG. 11 is a flowchart illustrating a process of resuming operation performed by the dynamic speed control unit. The operation restart processing is executed when, for example, an operation restart command is input to the robot controller after the suspension. The main points of each step are as follows.
[0123]
(Step H11): The stop position stored in the memory is read.
(Step H12): The robot is operated from the current robot position (for example, moving by jog feed) to the stop position read in Step H11.
(Step H13): Confirmation of completion of the operation in Step H12. Upon confirmation, the process proceeds to step H14.
(Step H14); Data necessary for the resuming operation is read out from the memory, read back to the operation planning unit, the interpolating unit, and the filter unit, and the state immediately before the hold is restored.
[0124]
(Step H15): The interpolation operation is performed from the stop position in the same manner as before the hold. At the same time, the dynamic override unit controls the acceleration override value OVa from the current override value (β = 0) so that the speed smoothly returns to the original speed v after a lapse of time t2.
The control of the acceleration override value OVa in the processing of step H15 uses the override asymptotic / arrival processing shown in the flowchart of FIG.
[0125]
That is, the update target value βN of the override in step L1 is set to βN = the value of β immediately before the hold. Further, s2 is divided by η (η is an appropriate positive integer other than 1) with the ITP conversion value of time t2 as s2, and f in step L2 is set to f = s2 / η. Then, n in the equation (7) for calculating Δβ in step L3 is calculated by βN = the value 0 of β immediately before the hold, and n = η.
[0126]
FIG. 13 shows a transition of the speed when the process of step H15 is performed. The override gradually goes from 0 to the original value, but it is necessary to completely output the movement command to the servo system in order to fully reflect the actual speed. Therefore, the speed transition does not rise linearly. Further, in order to make the operation smoother, the value of Δβ may not be a fixed value but may be gradually changed according to a smooth function (for example, an exponential function) to obtain a smooth transition of acceleration.
[0127]
【The invention's effect】
According to the present invention, it is possible to prevent a trajectory shift that has occurred in the related art in connection with the level of the override and the switching or temporary stop during the operation of the override. Further, through this, it is possible to improve the efficiency, reliability, and safety of the trajectory checking work by the test run after teaching. Further, since the trajectory deviation due to the switching or the temporary stop during the operation of the override is eliminated, the accuracy and safety of the robot operation are improved.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a framework of processing of a conventional method which has been performed inside a robot control device from an operation plan to a movement command output to a servo during program reproduction.
FIG. 2 is a view for explaining the reason why a trajectory shift occurs using a simple example in relation to the processing of the conventional method shown in FIG. 1;
FIG. 3 is a main block diagram illustrating a hardware configuration of a robot system including a robot control device to which the present invention is applied;
FIG. 4 is a diagram illustrating, in a form similar to FIG. 1, a framework of processing performed in the robot controller from an operation plan to a movement command output to a servo at the time of reproducing a program in the embodiment of the present invention.
FIG. 5 is a diagram illustrating an example of an override process in which a filter unit output is overridden by 50%.
FIG. 6 is a diagram for explaining the influence of the override process when the operations represented by the segments sg1 to sg7 and the operations represented by the segments sk1 to sk7 overlap in a synchronous relationship between sg6 and sg7 and sk1 and sk2. is there.
FIG. 7 is a diagram for describing temporary stop related processing in the present embodiment.
8 is a diagram illustrating, in a form slightly different from FIG. 4, a framework of processing performed in the robot controller from an operation plan to a movement command output to a servo during program reproduction according to the embodiment of the present invention.
FIG. 9 is a flowchart illustrating a point of an override process performed by a dynamic speed control unit.
FIG. 10 is a flowchart illustrating a main point of a hold process executed at the time of a temporary stop in the dynamic speed control unit.
FIG. 11 is a flowchart illustrating a main point of a process executed by the dynamic speed control unit when the operation is resumed after the suspension.
FIG. 12 is a diagram showing a change in speed when a hold process is performed.
FIG. 13 is a diagram showing a speed transition in a case where a process of gradually increasing the override in resuming the operation is performed.
FIG. 14 is a diagram showing a route operation assumed as a premise for the description of FIGS. 15 and 16;
FIG. 15 is a diagram illustrating an influence of a level of an override value on a trajectory in a corner portion in the path operation illustrated in FIG. 14, using an example of an override rate of 30%.
16 is a diagram illustrating an influence of a level of an override value on a trajectory in an acceleration / deceleration unit with respect to the path operation illustrated in FIG. 14, using a case of an override rate of 30% as an example.
FIG. 17 is a flowchart illustrating override asymptotic / arrival processing.
[Explanation of symbols]
1 Arm tip
10 hands
30 Robot controller
31 Host CPU
32 Shared RAM
33 Servo CPU
34 Servo amplifier
35 memory
36 Teaching operation panel interface
38 I / O device
37 Teaching operation panel
RB robot

Claims (10)

A robot controller having software means for outputting a movement command to a servomotor that drives each axis of the robot,
The software means obtains a movement amount of the robot to an operation target position, interpolates the movement amount in a certain cycle, and performs a filtering process on the interpolated output for acceleration / deceleration control.
With the movement command after the filtering process as an input, having a dynamic speed control means for correcting the movement command according to a designated command override value common to each axis,
It said dynamic rate control means, a command override value when the β% (0 ≦ β ≦ 100 ), said relative movement command, velocity (β / 100) times, also acceleration (β / ^{100) 2-fold} The robot control device according to claim 1, further comprising: a unit that outputs a movement command that: When the target override value is different from the current override value, it has a command override calculation means for smoothly changing the command override value for the dynamic speed control means from the current override value to the target override value. The robot control device according to claim 1. When temporarily stopping the robot during execution of the program, the target override value is set to 0, and the command override value for the dynamic speed control means is smoothly changed from the current override value to 0 by the command override calculation means. The robot control device according to claim 2, wherein the robot is decelerated and stopped by (1). 3. The method according to claim 2, wherein, when the robot is emergency-stopped during execution of the program, the target override value and the command override value are both set to 0, the movement command output is instantaneously set to 0, and the robot is immediately stopped. The robot control device according to item 1. In the case where the robot is temporarily stopped or an emergency stop is performed during execution of the program ram, and the operation is resumed after the stop, the command override calculating means can smoothly change the command override value from 0 to the target override value. The robot control device according to claim 2, wherein the robot is accelerated. The command override calculating means, wherein the command override value for the dynamic speed control means is changed stepwise by dividing into a specified number of divisions from a current override value to a target override value. The robot control device according to any one of claims 2 to 5. 3. The command override calculation means, wherein an instruction function for the dynamic speed control means is smoothly changed by using an exponential function from a current override value to a target override value. The robot control device according to claim 5. 6. The operation data stored in the robot controller near the time of the temporary stop, and the stored operation data is used when the operation is resumed. 2. The robot control device according to claim 1. 8. The operation plan according to claim 1, wherein the operation plan based on the operation program includes an orthogonal operation plan for performing an orthogonal operation for at least one operation section. Robot controller. The method according to claim 1, wherein the operation plan based on the operation program includes an axis operation plan for performing each axis operation for at least one operation section. A robot controller as described.

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