JP2005074546A - Interpolation point generating device for industrial robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an interpolation point generating device for an industrial robot which performs conveyance work without applying impact to workpieces in conveyance work of highly fragile workpieces. <P>SOLUTION: This interpolation point generating device for the industrial robot has: a maximum speed determining part 61 for computing the maximum speed of passing speed by inputting a circular interpolation radius, passing speed, allowable acceleration and the sharing rate of centrifugal acceleration and tangential acceleration generated at the passing speed; a Cartesian command value generating part 62 for computing the interpolation point position of a circular locus on a Cartesian space keeping the allowable acceleration by inputting the maximum speed of the passing speed, a circular interpolation start position, the circular interpolation radius, a circular interpolation center position, the allowable acceleration, and the sharing rate of centrifugal acceleration and tangential acceleration generated at the maximum speed of the passing speed; and a joint command value generating part 63 for computing the command value of each joint of the robot by applying a reverse kinematic technique to the interpolation point position of the circular locus. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an interpolation point generation device for an industrial robot, and more particularly to an industrial robot that generates an interpolation point when drawing an arc trajectory while protecting the allowable acceleration at the tip of a tool mounted on the tip of an arm of the industrial robot. The present invention relates to an interpolation point generation apparatus.

  In recent years, with the expansion of the application range of industrial robots for conveyance, various workpieces have been attached to workpiece gripping tools provided at the robot arm tips. Some of these workpieces are highly brittle, such as glass, which breaks with little impact and vibration. In transporting such highly brittle workpieces, it is important to operate at the allowable acceleration (allowable acceleration) and in the shortest possible time without changing the speed of the tool tip discontinuously. Yes.

  For example, as shown in FIG. 1, there is a method of interpolating an inward circular arc trajectory at a joint as a method for smoothing the trajectory at the tool tip of the robot that grips the workpiece. Further, in a polar coordinate robot as shown in FIG. 2, the tool tip portion draws an arc trajectory by simply operating the turning axis. In this way, operating the tool tip in an arcuate path is very important for smoothly operating the robot body.

Conventionally, there is a technique for operating the tool tip in an arc orbit while protecting the allowable acceleration. For example, in Patent Document 1 and Patent Document 2, the acceleration in the inward trajectory is calculated from the passing speed, and the calculated inward A configuration for protecting the allowable acceleration by correcting the passing speed so that the acceleration in the orbit is within the range of the allowable acceleration is disclosed.
JP 7-64621 A JP-A-8-339222

  However, in these methods of correcting the passing speed, as shown in FIG. 3, the centrifugal acceleration 32 determined by the passing speed can be protected, but the tangential acceleration 31 when accelerating and decelerating on the arc locus is taken into consideration. It has not been. Moreover, if a well-known acceleration / deceleration method is used when accelerating and decelerating on a conventional linear locus, the tangential acceleration 31 can be protected, but the centrifugal acceleration 32 cannot be considered. Actually, assuming a case where the circular trajectory is passed at the tangential speed as shown in FIG. 4 showing the time change of the tangential speed, the time change of the combined acceleration of the centrifugal acceleration 32 and the tangential acceleration 31 in this case is shown in FIG. As a result, the allowable acceleration value is partially exceeded at the acceleration peak. Thus, in the prior art, when accelerating and decelerating on an arc locus, there is a possibility that a composite acceleration of centrifugal acceleration and tangential acceleration exceeds the allowable acceleration. Therefore, in the prior art, there is a problem that it is difficult to perform the transfer operation without giving an impact to a highly brittle workpiece such as glass.

  The present invention has been made to solve the above-mentioned problems of the prior art, and gives an impact to a workpiece in the transfer work of highly brittle workpieces such as glass using a manipulator such as a robot. An object of the present invention is to provide an interpolation point generation device for an industrial robot capable of carrying out a transfer operation without any problem.

  In order to achieve the above-described object, the present invention provides an industrial robot characterized by having a maximum speed determining unit 61, a Cartesian command value generating unit 62, and a joint command value generating unit 63 having the following functions. An interpolation point generator was provided.

  That is, the maximum speed determining unit 61 is based on circular interpolation information including at least the circular interpolation radius r and the passing speed v, and the type and form of the work gripped by the work gripping tool provided at the arm tip of the robot. By inputting the set allowable acceleration a and the sharing rate α between the centrifugal acceleration a1 generated at the passing speed v and the tangential acceleration, the maximum speed v1 of the passing speed is calculated and output.

  Further, the Cartesian command value generation unit 62 includes the maximum speed v1 of the passing speed calculated and output by the maximum speed determination unit 61, at least the circular interpolation start position (xs, ys), the circular interpolation radius r, and the circular interpolation center position. By inputting the circular interpolation information including (x0, y0), the allowable acceleration a, and the sharing rate α between the centrifugal acceleration a2 and the tangential acceleration a3 generated at the maximum speed v1 of the passing speed, the allowable acceleration a The interpolation point position (x (n), y (n)) of the arc trajectory on the Cartesian space that observes is calculated and output.

  Further, the joint command value generation unit 63 applies the inverse kinematics method to the interpolation point position (x (n), y (n)) of the circular arc locus in the Cartesian space input from the Cartesian command value generation unit 62. By doing so, the command value of each joint of the robot is calculated and output.

  With this configuration, first, the maximum speed determination unit 61 obtains the centrifugal acceleration a1 from the passing speed v and the circular interpolation radius r, and this centrifugal acceleration a1 is obtained by multiplying the allowable acceleration a by an appropriate ratio α. The maximum speed v1 of the passing speed so as not to exceed is obtained. Next, in the Cartesian command value generation unit 62, the tangential speed at which the combined acceleration of the centrifugal acceleration a2 and the tangential acceleration a3 generated at the maximum speed v1 of the passing speed calculated by the maximum speed determination unit 61 does not exceed the allowable acceleration a. v (n) is obtained, and an interpolation point (x (n), y (n)) on the circular arc trajectory that satisfies the tangential velocity v (n) and the maximum velocity v1 of the passing velocity is calculated. As a result, it is possible to obtain an interpolation point (x (n), y (n)) on the arc locus such that the acceleration generated at the tip of the robot does not exceed the allowable acceleration a. Finally, the joint command value generation unit 63 calculates a command value for each joint of the robot based on the obtained interpolation point (x (n), y (n)) on the arc locus. As a result, the acceleration generated at the tip of the robot does not exceed the allowable acceleration a.

  According to the present invention, it becomes possible to control the combined acceleration of the centrifugal acceleration and the tangential acceleration in the arc trajectory or the inward movement so that the acceleration generated at the tip of the robot does not exceed the allowable acceleration. In the work of transporting highly brittle workpieces such as used glass, it has become possible to carry out the work without impacting the work.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 6 is a block diagram showing an embodiment of an interpolation point generating apparatus for an industrial robot according to the present invention.

  In FIG. 6, reference numeral 61 denotes a maximum speed determining unit that calculates the maximum speed v1 of the passing speed. The maximum speed determination unit 61 receives circular interpolation information including at least a circular interpolation radius r and a passing speed v. Further, the maximum speed determination unit 61 includes an allowable acceleration a at the tool tip set based on the type and form of the workpiece gripped by the tool for gripping the workpiece provided at the tip of the robot arm, and the passage. A sharing rate α between the centrifugal acceleration a1 generated at the speed v and the tangential acceleration is input. On the other hand, the maximum speed determining unit 61 outputs the maximum speed v1 of the passing speed used in the current circular interpolation calculation.

  Reference numeral 62 denotes a Cartesian command value generation unit that calculates the interpolation point position (x (n), y (n)) of the circular arc locus on the Cartesian space while keeping the allowable acceleration a. The Cartesian command value generation unit 62 receives the maximum passing speed v1 used in the circular interpolation calculation calculated and output by the maximum speed determination unit 61 described above. The Cartesian command value generation unit 62 receives circular interpolation information including at least a circular interpolation start position (xs, ys), a circular interpolation radius r, and a circular interpolation center position (x0, y0). Further, the Cartesian command value generation unit 62 includes the above-described allowable acceleration a set based on the type and form of the work gripped by the work gripping tool provided at the arm tip of the robot, and the passing speed. The sharing rate α between the centrifugal acceleration a2 and the tangential acceleration a3 generated at the maximum speed v1 is input. On the other hand, the Cartesian command value generation unit 62 outputs the interpolation point position (x (n), y (n)) in the Cartesian space.

  Reference numeral 63 denotes a joint command value generation unit that calculates a command position of each joint of the robot based on information on the interpolation point position in the Cartesian space. The joint command value generation unit 63 receives the interpolation point position (x (n), y (n)) in the Cartesian space calculated and output by the Cartesian command value generation unit 62 described above. On the other hand, the joint command value generation unit 63 outputs, as a final output, command values (position information) for each joint of the robot necessary for drawing an arc locus while protecting the allowable acceleration a.

  Next, each process performed in the above-described maximum speed determination unit 61, Cartesian command value generation unit 62, and joint command value generation unit 63 will be described.

  First, the calculation process of the maximum speed v1 of the passing speed used in the circular interpolation calculation performed in the maximum speed determination unit 61 will be described. From the circular interpolation radius r and the passing speed v included in the circular arc trajectory information input to the maximum speed determining unit 61, the centrifugal acceleration a1 generated at the circular interpolation radius r and the passing speed v is obtained by Expression (1).

この式（１）に基づくと、許容加速度ａに通過速度ｖにて生じる遠心加速度ａ１と接線加速度との分担率α（αは１未満）を乗じたものを許容される遠心加速度とすると、通過速度の最高速度ｖ１は、式（２）により求められる。

Based on this equation (1), if the allowable acceleration is a value obtained by multiplying the allowable acceleration a by the sharing rate α of the centrifugal acceleration a1 generated at the passing speed v and the tangential acceleration (α is less than 1), The maximum speed v1 of the speed is obtained by the equation (2).

なお、式（２）において、ｓｑｒｔ（）の表記は、括弧内の平方根を意味する。

In addition, in Formula (2), the notation of sqrt () means the square root in parentheses.

  Next, the calculation processing of the interpolation point position (x (n), y (n)) of the circular arc locus in the Cartesian space that observes the allowable acceleration a performed in the Cartesian command value generation unit 62 will be described. Here, first, the tangential acceleration a (n) at the current interpolation calculation time when the tangential velocity at the previous interpolation calculation time is set to v (n−1) is calculated by Expression (3).

この式（３）においては、前述したように、ａは許容加速度、αは通過速度の最高速度ｖ１にて生じる遠心加速度ａ２と接線加速度ａ３との分担率α、ｒは円弧補間半径である。次に、この式（３）において算出された今回の補間演算時刻における接線加速度ａ（ｎ）をもとに、今回の補間演算時刻における接線速度ｖ（ｎ）を式（４）により算出する。

In this equation (3), as described above, a is an allowable acceleration, α is a sharing rate α between the centrifugal acceleration a2 and the tangential acceleration a3 generated at the maximum passing speed v1, and r is a circular interpolation radius. Next, based on the tangential acceleration a (n) at the current interpolation calculation time calculated in Expression (3), the tangential velocity v (n) at the current interpolation calculation time is calculated according to Expression (4).

この式（４）において、ｄｔは補間演算周期である。前述の式（２）および式（３）より、通過速度の最高速度ｖ１にて生じる遠心加速度ａ２および接線加速度ａ３を式（５）および式（６）によりそれぞれ算出する。

In this equation (4), dt is an interpolation calculation cycle. From the above formulas (2) and (3), the centrifugal acceleration a2 and the tangential acceleration a3 generated at the maximum passing speed v1 are calculated by the formulas (5) and (6), respectively.

この式（５）および式（６）においては、前述したように、ａは許容加速度、αは通過速度の最高速度ｖ１にて生じる遠心加速度ａ２と接線加速度ａ３との分担率αである。次に、これら式（５）および式（６）において算出された遠心加速度ａ２および接線加速度ａ３をもとに、遠心加速度ａ２と接線加速度ａ３との複合加速度を算出する。この場合の複合加速度はｓｑｒｔ（ａ２×ａ２＋ａ３×ａ３）から計算できるので、これら式（５）および式（６）より複合加速度はａとなる。したがって、この場合の複合加速度は前述した許容加速度と同一になる。これにより、遠心加速度と接線加速度との複合化速度を制御するようにすれば、ロボットの先端部における加速度が許容加速度を超えないことがわかる。

In Expressions (5) and (6), as described above, a is the allowable acceleration, and α is the sharing ratio α between the centrifugal acceleration a2 and the tangential acceleration a3 that occur at the maximum passing speed v1. Next, based on the centrifugal acceleration a2 and the tangential acceleration a3 calculated in the equations (5) and (6), a combined acceleration of the centrifugal acceleration a2 and the tangential acceleration a3 is calculated. Since the composite acceleration in this case can be calculated from sqrt (a2 * a2 + a3 * a3), the composite acceleration is a from these expressions (5) and (6). Therefore, the composite acceleration in this case is the same as the allowable acceleration described above. Thus, it can be seen that if the combined speed of the centrifugal acceleration and the tangential acceleration is controlled, the acceleration at the tip of the robot does not exceed the allowable acceleration.

  From the tangential velocity v (n) calculated from the above equation (4), the interpolation point position (x (n), y (n)) of the circular arc locus on the Cartesian space at the circular interpolation radius r is as follows. Ask. From the tangential velocity v (n) calculated from the above equation (4), the angular velocity w (n) of the operation on the circular arc at the circular interpolation radius r is calculated by the equation (7).

ここで、図７に示すように、前回の補間演算時刻における中心角度がθ（ｎ−１）で、今回の補間演算時刻における中心角度がθ（ｎ）であったとすると、前述の式（７）から算出される角速度ｗ（ｎ）より、今回の補間演算時刻における中心角度θ（ｎ）は式（８）により算出される。

Here, as shown in FIG. 7, if the center angle at the previous interpolation calculation time is θ (n−1) and the center angle at the current interpolation calculation time is θ (n), the above-described formula (7 ), The central angle θ (n) at the current interpolation calculation time is calculated by the equation (8).

この式（７）から算出される中心角度θ（ｎ）より、円弧補間半径ｒにおけるデカルト空間上の円弧軌跡の補間点位置（ｘ（ｎ），ｙ（ｎ））は、式（９）および式（１０）より算出することができる。

From the center angle θ (n) calculated from the equation (7), the interpolation point position (x (n), y (n)) of the arc locus on the Cartesian space at the arc interpolation radius r is expressed by the equation (9) and It can be calculated from equation (10).

これら式（９）および式（１０）において、（ｘ０，ｙ０）は前述した円弧軌跡情報としてデカルト指令値生成部６２に入力される円弧補間中心位置である。また、θ０は円弧開始中心角度であり、これは前述した円弧軌跡情報としてデカルト指令値生成部６２に入力される円弧開始中心角度（ｘ０，ｙ０）および円弧補間開始位置（ｘｓ，ｙｓ）より、式（１１）および式（１２）から算出する。

In these equations (9) and (10), (x0, y0) is a circular interpolation center position input to the Cartesian command value generation unit 62 as the circular arc trajectory information described above. Further, θ0 is the arc start center angle, and this is based on the arc start center angle (x0, y0) and the arc interpolation start position (xs, ys) input to the Cartesian command value generation unit 62 as the arc trajectory information described above. It calculates from Formula (11) and Formula (12).

以上のように式（３）から式（１２）までの処理をデカルト指令値生成部６２において行い、これにより円弧補間半径ｒにおけるデカルト空間上の円弧軌跡の補間点位置（ｘ（ｎ），ｙ（ｎ））を算出する。

As described above, the processing from Equation (3) to Equation (12) is performed in the Cartesian command value generation unit 62, whereby the interpolation point position (x (n), y of the arc locus on the Cartesian space at the arc interpolation radius r). (N)) is calculated.

  Finally, a process for calculating the command position of each joint of the robot performed in the joint command value generation unit 63 will be described. The joint command value generation unit 63 receives the interpolation point position (x (n), y (n)) in the Cartesian space calculated and output by the Cartesian command value generation unit 62 described above. By applying a well-known inverse kinematics method to the interpolation point position (x (n), y (n)) in the Cartesian space, a command value for each joint of the robot is calculated. By outputting the command value of each joint of the robot to a servo control unit (not shown), the robot can be operated while maintaining the allowable acceleration.

It is the conceptual diagram which showed the method of interpolating an inward arc track | orbit at a joint. It is the conceptual diagram which showed the circular arc track | orbit of the tool front-end | tip part in a polar coordinate robot. It is explanatory drawing which showed the tangential acceleration 31 and the centrifugal acceleration 32. FIG. It is the graph which showed the time change of the tangential speed in the case of passing an arc locus at a tangential speed. FIG. 5 is a graph showing a time change of a composite acceleration of a centrifugal acceleration 32 and a tangential acceleration 31 generated when operating at the tangential velocity shown in FIG. 4. It is the block diagram which showed one Embodiment of the interpolation point production | generation apparatus of the industrial robot which concerns on this invention. It is the conceptual diagram which showed the circular arc track | orbit in case the last center angle is (theta) (n-1) and this center angle is (theta) (n).

Explanation of symbols

31 Tangential Acceleration 32 Centrifugal Acceleration 61 Maximum Speed Determination Unit 62 Cartesian Command Value Generation Unit 63 Joint Command Value Generation Unit

Claims (1)

The circular interpolation information including at least the circular interpolation radius and the passing speed, the allowable acceleration set based on the type and form of the work gripped by the work gripping tool provided at the end of the robot arm, and the passing speed A maximum speed determination unit that calculates and outputs the maximum speed of the passing speed by inputting the centrifugal acceleration and the tangential acceleration sharing ratio generated by
It occurs at the maximum speed of the passing speed calculated by the maximum speed determining unit, the circular interpolation information including at least the circular interpolation start position, the circular interpolation radius and the circular interpolation center position, the allowable acceleration, and the maximum speed of the passing speed. A Cartesian command value generation unit that calculates and outputs an interpolation point position of an arc locus on a Cartesian space that protects the allowable acceleration by inputting a sharing rate between centrifugal acceleration and tangential acceleration;
A joint command value generation unit that calculates and outputs a command value of each joint of the robot by applying an inverse kinematics method to the interpolation point position of the circular arc locus on the Cartesian space calculated by the Cartesian command value generation unit; ,
An interpolation point generating apparatus for an industrial robot characterized by comprising:

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