JPH11249723A - Method and device for controlling robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for controlling robot with which inner turning can be continued even when a robot is restarted in the middle of inner turning. SOLUTION: A controller 1 for robot is provided with a first interpolating command generating part 3 for generating an interpolating command value for moving the robot along with a teaching route and a second interpolating command value generating part 4 having a circular arc track generating means 41 and an operating speed calculating means 42 for calculating speed for moving the robot on that circular arc track. Then, the circular arc track is generated concerning a teaching point P to which accuracy setting (s) is performed, and the top end of a robot arm is internally turned along with that circular arc track.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a control method and a control device for a robot. More specifically, the present invention relates to a control method and a control device for a robot that can continue the inward rotation even if the robot is restarted halfway inward.

[0002]

2. Description of the Related Art Conventionally, when it is not necessary to move a robot strictly along a teaching point, a so-called inward rotation of the tip of a robot arm is performed to reduce a cycle time.

However, for example, when the robot is controlled by linear interpolation, if the robot is stopped halfway inward and restarted from that location, the robot moves to the next teaching point by linear operation without continuing the inward rotation. For example, as shown in FIG. 8, the teaching points are P ₁ , P ₂ , and P ₃ , the robot is stopped at a point Q in the middle of inward rotation, and restarted from the point Q, the robot follows the trajectory of the straight line QP _3. Operate. As described above, since the trajectory of the continuous operation and the trajectory of the stop and the restart of the operation in the middle are different, there is a problem that it takes time to teach.

Although various proposals have been made to solve the above problems, none of them has room for improvement and is not perfect.

[0005] For example, Japanese Patent Application Laid-Open No. H08-123531 discloses that a tool or a work point set near a tip of a movable portion of an automatic working machine is moved according to a taught path and a taught speed. A trajectory control method, wherein a transition is made such that an end point of a first teaching path and a start point of a second teaching path are smoothly connected between two same teaching paths near a connection point of the two teaching paths. In a method of generating a trajectory and controlling the movement of a working point according to the generated transition trajectory, a pre-deceleration section having a length of 0 or more for decelerating the generated transition trajectory on a first teaching path, two teachings A transition section of length 0 or more that moves away from the path, a post-acceleration section of length 0 or more that accelerates on the second teaching path,
A trajectory control method characterized by independently setting an acceleration / deceleration method for each section has been proposed.

Japanese Patent Application Laid-Open No. 8-339222 discloses a teaching point for providing a reference for a trajectory on which a tip of a robot moves, a movement command for designating the shape of the trajectory based on the teaching point, and a tip on the trajectory. Inputting the teaching point data including the moving speed for specifying the moving speed of the unit and the allowable path error for specifying the maximum value of the error between the teaching point and the trajectory, The position and orientation of an inward start point, which is a point to start inward of a trajectory that inward without passing through the node of the polygonal line of the polygonal path specified by the teaching point data, and an inward end point, which is an end point It has inward rotation start and end point setting means to calculate the position and orientation in advance before the operation of the robot and to register it in the teaching point data, and as the tip moving speed when performing parabolic interpolation, each joint axis of the robot per unit time An upper limit travel speed setting in which the change in the rotational speed does not exceed the allowable change determined from the maximum acceleration determined for each joint axis beforehand, before the robot operates, and registers it in the teaching point data Means, if there are two or more inwardly rotating sections in a row, from the arrival speed of the tip at the end point of a certain parabolic trajectory to the tip movement speed at the start point of the next parabolic trajectory,
Speed continuity means for preliminarily adjusting the upper limit movement speed of each parabolic trajectory and registering it in the teaching point data so that acceleration or deceleration can be achieved by accelerating or decelerating the linear movement section therebetween within the allowable angle acceleration value of the joint axis or less A parabolic interpolation calculating means for generating, by a parabolic trajectory, a trajectory inwardly traversing a polygonal path according to teaching data newly registered by the inward turning start / end point setting means, the upper limit moving speed setting means, and the speed continuation means. There has been proposed an apparatus for generating a robot trajectory that has a certain trajectory calculation means.

[0007] However, in the proposal of Japanese Patent Application Laid-Open No. H08-123531, since the deceleration area of the first teaching path and the acceleration area of the second teaching path are combined, the linear velocity of the robot in the combining area is kept constant. In the proposal of Japanese Patent Application Laid-Open No. 8-339222, the moving speed is determined so as not to exceed the maximum acceleration. (See FIG. 9).

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and has a control method and a control method for a robot capable of continuing the inner rotation even if the robot is restarted from the middle of the inner rotation. It is intended to provide a device.

[0009]

A robot control method according to the present invention is a robot control method for moving the tip of a robot arm along a teaching path. It is characterized in that the robot moves inward from a point to a distance point corresponding to the accuracy setting by an arc trajectory.

[0010] More specifically, the robot control method of the present invention is a robot control method for moving the tip of a robot arm along a teaching path, comprising the steps of setting accuracy with respect to a desired teaching point; The method includes a step of generating an arc trajectory related to the teaching point for which the accuracy has been set, and a step of rotating the tip of the robot arm inward along the arc trajectory.

In the method for controlling a robot according to the present invention,
When a speed vector discontinuity occurs when transitioning from the teaching path to the arc path and / or when transitioning from the arc path to the teaching path, the speeds are superimposed in a minute section at a point where the velocity vector discontinuity occurs. Preferably, a procedure is added.

Further, in the robot control method of the present invention, when the absolute value of the speed at the time of transition from the teaching path to the circular path is different from the absolute value of the speed at the time of transition from the circular path to the teaching path, The absolute value of the operation speed of the distal end of the robot arm on the arc trajectory may be continuously changed so that the absolute values of the speeds at the two locations match.

[0013] On the other hand, a robot control apparatus according to the present invention is a robot control apparatus used in a robot control method for moving the tip of a robot arm along a teaching path, wherein the control apparatus includes a teaching path interpolation apparatus. An arc trajectory comprising: a first interpolation command value generation unit for generating a command value; an arc trajectory generating means for generating an arc trajectory; and an operation speed calculation means for calculating an operation speed when moving on the generated arc trajectory. A second interpolation command value generating section for generating an interpolation command value when moving upward, and an interpolation command value output section for outputting interpolation command values from the first interpolation command value generating section and the second interpolation command value generating section The arc trajectory generation means generates an arc trajectory for the teaching point for which the accuracy has been set, and the operation speed calculation means generates the circular trajectory generated by the arc trajectory generation means. Wherein the operating speed of the trajectory is calculated.

In the robot control device according to the present invention,
When a speed vector discontinuity occurs when transitioning from a teaching path to an arc path and / or when transiting from an arc path to a teaching path, the operation speed calculation means calculates a minute section of a point at which the velocity vector discontinuity occurs. It is preferable that the operation speed is calculated by superimposing the speeds in.

In the robot control apparatus according to the present invention, when the absolute value of the speed at the time of transition from the teaching path to the circular path is different from the absolute value of the speed at the time of transition from the circular path to the teaching path, By the operating speed calculating means,
The operating speed may be calculated by continuously changing the absolute value of the operating speed of the distal end of the robot arm on the arc trajectory so that the absolute values of the speeds at the two locations match.

Here, the minute section is 128 ms or less,
Preferably, it is set to 64 ms or less.

[0017]

Since the present invention is configured as described above, even if the robot is restarted halfway inward, the robot makes an inward rotation along the same trajectory as when the robot is continuously operated. Therefore, the teaching operation is simplified.

Further, according to the preferred embodiment of the present invention in which the speeds are superposed in a minute section of the point where the speed vector is discontinuous, adverse effects on the robot such as impact at the point where the speed vector is discontinuous are alleviated. Is done.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments with reference to the accompanying drawings, but the present invention is not limited to only such embodiments.

FIG. 1 shows a control device according to an embodiment used in the robot control method of the present invention.
A teaching data storage unit 2 for storing teaching data, a first interpolation command value generation unit 3 for generating an interpolation command value for a teaching path, and a first interpolation command value for generating an arc trajectory interpolation command value for performing an inward rotation by performing a circular motion. (2) It comprises an interpolation command value generation section 4 and an interpolation command value output section 5 as main parts.

The control device 1 having such a configuration is specifically realized by combining a ROM, a RAM, an input / output interface, etc., in which a control program corresponding to processing to be described later is stored, mainly using a CPU. Is done. The teaching data storage unit 2 is the same as that conventionally used in a robot control device for storing teaching data, and thus a detailed description thereof is omitted.

The first interpolation command value generating section 3 generates an interpolation command value of the teaching path up to the accuracy setting distance by linear interpolation or circular interpolation based on the teaching data, and an interpolation command value of the teaching path after the completion of the circular path. As the configuration, a configuration conventionally used for generating an interpolation command value in a robot controller can be appropriately used.

The second interpolation command value generating section 4 generates an interpolation command value for causing the robot to move on the circular locus. The circular locus generating means 41 for generating the circular locus and the operation on the circular locus. Operating speed calculating means 42 for calculating speed
And an arc locus generating means 4
1 is to make a perpendicular line inward from the start point and the end point of the specified accuracy setting distance s and generate an arc trajectory passing through the start point and the end point around the intersection of both perpendicular lines,
The operation speed calculation means 42 calculates the operation speed on the circular arc locus based on the operation speeds at the start point and the end point. A specific example of the arc trajectory generation and a specific example of the operation speed calculation will be described later.

The interpolation command value output section 5 sequentially outputs the interpolation command values from the first interpolation command value generation section 3 and the second interpolation command value generation section 4.

Next, generation of an arc locus and calculation of an operating speed on the generated arc locus will be described.

A) When the taught path consists of a combination of linear paths As shown in FIG. 2, there are taught points P ₁ , P ₂ , and P ₃ , and between the taught points, that is, between P ₁ P ₂ and P ₂ between P ₃ is operated in a straight line, the precision setting for teaching point P ₂ to s. That is,
The distance the robot to the teaching point P ₂ has reached the point to Q ₁ s, cause the process proceeds to the next step. I mean,
Turn inward. Then, this inward rotation is performed by an arc locus.

The generation of the arc trajectory is performed by first setting the accuracy s from the teaching point P ₂ to each of the paths P ₁ P ₂ and P ₂ P _3.
Are set respectively corresponding to points Q ₁ and Q ₂ . Next, circles tangent to the points Q ₁ and Q ₂ are generated, and arcs Q _{1 and} Q ₂ are cut out from the circles, and are used as arc trajectories for making the robot go inward. The circles tangent to the points Q ₁ and Q ₂ are formed by a simple mathematical theory, for example, at the intersection R with the perpendicular of the point Q _{1 and} the perpendicular of the point Q _2.
It is created by setting the line segment R ₁ Q ₁ as a radius with ₁ as the center.

[0028] Thus, by setting the circular arc path for the inward turning beforehand robot can even stopped at point Q ₃ in the inner circumference, the operation was on the circular arc path from point Q ₃ are on reboot Can be.

The operating speed of the robot when operating the circular locus is calculated as follows.

The initial speed at the point Q ₁ on the arc is determined by the route P ₁ P ₂
And the same speed as at point Q ₁ in a point on the arc Q ₂
Terminal velocity of the, and the same speed as at point Q ₂ in the path P ₂ P _3. In this case, when there is a difference in the absolute value of the velocity in the absolute value of the velocity and the point Q ₂ at the point Q ₁ is the absolute value of the velocity the absolute value of the velocity on the arc Q ₁ Q ₂ is at the point Q _1, the point Q ₂ Is determined by appropriately distributing the difference from the absolute value of the speed in the above, for example, by uniformly distributing or accelerating / decelerating. For example, if it is the operation plan to the absolute value of the velocity zero at the teaching point P _2, the movement plan from the teaching point P ₁ to the teaching point P ₂ is as shown in FIG. 3 (a), teaches movement plan from the point P ₂ to the teaching point P ₃ is 3
The result is as shown in FIG. Therefore, the absolute value of the velocity at the point Q ₁ is v _1, and the absolute value of the velocity at the point Q ₂ is a v _2. Therefore, the absolute value v of the velocity at the point Q on the arc Q ₁ Q ₂ is calculated using v ₁ and v ₂ . For example, it is calculated by the following equation (1).

V = v ₁ + (v ₂ −v ₁ ) (t−t ₁ ) / (t ₂ −t ₁ ) (1) where t: time t at the point Q t ₁ : time t at the point Q _{1 2:} the time at the point Q ₂

B) When the taught path consists of a combination of a straight path and an arc path As shown in FIG. 4, there are teaching points P ₁ , P ₂ , P ₃ , and P ₄ , and between teaching points P _{1 and} P ₂ Is operated in a straight line, a circular operation is performed between the teaching points P _{2 and} P _{3 and} between the teaching points P _{3 and} P ₄ on the same circular arc, and the accuracy setting for the teaching point P ₂ is s. That is, when the distance of the similar to the robot to the teaching point P ₂ has reached the point to Q ₁ s, is the inward turning the robot through circular path.

The generation of the circular arc locus is performed by first setting the linear path P₁
P_TwoTeaching point P_TwoFrom the point Q corresponding to s to the accuracy setting₁Set
And the arc path P_TwoP_ThreeP_FourTaught a string of length s
Point P _TwoFrom the other end of the string to point Q_TwoAnd About
Then, in the same manner as above, the point Q₁And point Q_TwoCreate a circle that touches
And the arc Q₁Q_TwoInward around the robot
Arc trajectory Q₁Q_TwoAnd In this case, the straight path P₁
P_TwoAnd arc path P_TwoP_ThreeP_FourMay not be on the same plane.

Therefore, when the robot reaches the point Q ₁ on the straight path P ₁ P ₂ , it moves on the circular arc path Q ₁ Q ₂ , and when it reaches the point Q ₂ , it moves on the circular path P ₂ P ₃ P ₄ Transition. However, in the transition from a straight path P ₁ P ₂ at point Q ₁ to the circular path Q ₁ Q _2, although the direction of the velocity vector is always continuous, circular path Q ₁ Q ₂ at point Q ₂
In the transition from to the arc path Q ₂ P ₃ P ₄ , the velocity vector becomes discontinuous. Therefore, the discontinuous point, the impact on the robot in the clogging point Q ₂ occurs. However, since the angle θ between the two velocity vectors at the discontinuous point is 0 ≦ θ <(π / 2), the impact generated on the robot at the discontinuous point is caused by the superposition of the velocities as shown in FIG. It can be alleviated by performing with small section near the point Q _2. Specifically, the minute section is appropriately selected within a range of 128 ms or less in consideration of the time required for the movement of the robot and the speed of the robot. When the moving speed of the robot is high, it is preferable to select the speed within a range of 64 ms or less. In addition, this minute section may be set to 0 ms in some cases.

For example, as shown in FIG. 5, the arc locus Q ₁ Q ₂
By operating the upper deceleration area and the acceleration area of the arc path Q ₂ P ₃ P ₄ at the speed obtained by superimposing, the adverse effect on the robot at the discontinuity point of the speed vector can be reduced. The operation speed on the arc trajectory Q ₁ Q ₂ is calculated in the same manner as in the above A.

[0036] Thus, by setting the circular arc path for the inward turning beforehand robot, even when stopped at the point Q ₃ all around the inner robot, circular path from point Q ₃ are at restart Q ₁ Q ₂ Can work on top.

C) When the taught path consists of a combination of arc paths As shown in FIG. 6, there are teaching points P ₁ , P ₂ , P ₃ , and P ₄ , and an arc between the teaching points P _{1 and} P ₂ ( Hereinafter, it is referred to as a first arc path.)
The upper part is moved in an arc, and the distance between the teaching points P _{2 and} P ₃ and the teaching points P ₃ P ₄
During different same arc (hereinafter, second of arc path) and a previous arc on is circular motion, and the accuracy setting for teaching point P ₂ to s.

[0038] The generation of the circular path sets a Q ₁ point corresponding to s First arcuate path P ₁ P ₂ from the teaching point P ₂ on the accuracy setting, second arcuate path P ₂ P ₃ P ₄ Teaching point P ₂
To set the Q ₂ points corresponding to the s to the accuracy settings from. The setting of these points Q ₁ and Q ₂ is performed in the same manner as the setting of the point Q ₂ in the arc path Q ₂ P ₃ P ₄ of B. Next, a circle tangent to the points Q ₁ and Q ₂ is created in the same manner as above.
An arc Q ₁ Q ₂ is cut out from the circle to obtain an arc locus Q ₁ Q ₂ that makes the robot inward. In this case, the first arc path P ₁ P ₂
And the second arc path Q ₂ P ₃ P ₄ need not be on the same plane.

Therefore, the robot moves the first arc path P ₁
When the point Q ₁ is reached on P ₂ , it moves on an arc trajectory Q ₁ Q ₂ , and when the point Q ₂ is reached, the second arc path Q ₂ P ₃
To migrate over to P _4. In this case, since the direction discontinuity of the velocity vector at different points Q ₁ and the B, performs superposition of speed for small section in the vicinity of the point Q _1, adverse effects of the discontinuity of the point Q ₁ definitive velocity vector (See FIG. 7).

As described above, by setting an arc trajectory for inwardly rotating the robot in advance, even if the robot stops at the point Q ₃ while moving inward, the arc trajectory Q ₁ Q ₂ from the point Q ₃ when restarting. Can work on top.

As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to only such embodiments, and various modifications are possible. For example, in the embodiment, it is described that the number of inward turns is one. However, the number of inward turns can be appropriately set, and the accuracy setting of the inward turns can be different. For example, increase the accuracy setting at a certain location,
The cycle time can be minimized by reducing the accuracy setting at other locations.

[0042]

As described above, according to the present invention, the following excellent effects can be obtained.

(1) The robot can be turned inward by a desired arc trajectory.

(2) Since the arc trajectory for inward rotation is predetermined, even if the robot is stopped halfway inward and restarted from that position, the robot moves along the same trajectory as in continuous operation. The work is simplified.

(3) Since the arc locus can be changed by changing the accuracy setting, the operation path can be optimized and the cycle time can be minimized.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control device used for a robot control method according to the present invention.

FIG. 2 is an explanatory diagram of creation of an arc trajectory in a case where a teaching route is a combination of straight routes.

[Figure 3] is an explanatory view of the operation plan in the teaching path shown in FIG. 2, the (a) shows the taught path P ₁ P _2, the (b) shows the taught path P ₂ P _3.

FIG. 4 is an explanatory diagram of the creation of an arc trajectory in the case where the teaching path is a combination of a straight path and an arc path.

FIG. 5 is an explanatory diagram of superimposition of velocities in the vicinity of a point where a velocity vector is discontinuous in the path shown in FIG. 4;

FIG. 6 is an explanatory diagram of the creation of an arc trajectory in the case where the teaching path is a combination of an arc path and an arc path.

FIG. 7 is an explanatory diagram of superimposition of velocities near points where velocity vectors become discontinuous in the route shown in FIG. 6;

FIG. 8 is an explanatory diagram in a case where the robot is restarted halfway inward by a conventional robot control method.

9A and 9B are explanatory diagrams of a case where the robot is operated according to the proposal of Japanese Patent Application Laid-Open No. 8-339222, wherein FIG. 9A shows a route, and FIG. 9B shows a tip speed of the robot on the route.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 control device 2 teaching data storage unit 3 first interpolation command value generation unit 4 second interpolation command value generation unit 41 arc trajectory generation unit 42 operation speed calculation unit 5 interpolation command value output unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuyasu Shimomura 1-1, Kawasaki-cho, Akashi-shi Kawasaki Heavy Industries, Ltd. Inside the Akashi Plant (72) Inventor Mitsui Hiratsuka 1-1, Kawasaki-cho, Akashi-shi Kawasaki Heavy Industries, Ltd. Inside the company Akashi factory

Claims (11)

[Claims] 1. A robot control method for moving a tip of a robot arm along a teaching path, wherein, for a teaching point for which an accuracy setting has been made, an arc trajectory extends between the teaching point and a distance point corresponding to the accuracy setting. A robot control method characterized by causing the robot to rotate inward by means of a robot. 2. A method for controlling a robot for moving a tip of a robot arm along a teaching path, comprising the steps of: setting a precision relating to a desired teaching point; and generating an arc trajectory relating to the teaching point having the precision setting. And a step of inwardly moving the tip of the robot arm along the arc trajectory. 3. When a speed vector discontinuity occurs when transitioning from a teaching path to an arc trajectory and / or when transitioning from a circular arc trajectory to a teaching path, the velocity is reduced in a minute section at a point where the velocity vector discontinuity occurs. 3. The control method for a robot according to claim 2, wherein a procedure for superimposing is added. 4. The method according to claim 3, wherein the minute section is 128 ms or less. 5. The robot control method according to claim 4, wherein the minute section is 64 ms or less. 6. When the absolute value of the speed at the time of transition from the teaching path to the circular path is different from the absolute value of the speed at the time of transition from the circular path to the teaching path, the movement of the tip of the robot arm on the circular path 3. The robot control method according to claim 2, wherein the absolute value of the speed is continuously changed so that the absolute values of the speeds at the two locations coincide with each other. 7. A robot controller used for a robot control method for moving a tip of a robot arm along a teaching path, wherein the controller generates a teaching path interpolation command value.
Interpolation when moving on an arc trajectory, comprising: an interpolation command value generating unit, an arc trajectory generating means for generating an arc trajectory, and an operation speed calculating means for calculating an operation speed when moving on the generated arc trajectory A second interpolation command value generation unit for generating a command value; and an interpolation command value output unit for outputting interpolation command values from the first interpolation command value generation unit and the second interpolation command value generation unit; A robot that generates an arc trajectory for the teaching point for which the accuracy has been set by the generation unit, and that calculates an operation speed in the arc trajectory generated by the arc trajectory generation unit by the operation speed calculation unit; Control device. 8. When a speed vector discontinuity occurs when transitioning from a teaching path to an arc trajectory and / or when transitioning from an arc trajectory to a teaching path, the operation speed calculation means determines that the velocity vector discontinuity occurs. 8. The robot control device according to claim 7, wherein the motion speed is calculated by superimposing the speeds in a minute section of the generated point. 9. The robot control device according to claim 8, wherein the minute section is 128 ms or less. 10. The robot control device according to claim 9, wherein the minute section is 64 ms or less. 11. When the absolute value of the speed at the time of transition from the teaching path to the circular path is different from the absolute value of the speed at the time of transition to the teaching path from the circular path, the operation speed calculating means determines the speed on the circular path. 8. The operation speed of the robot according to claim 7, wherein the operation speed is calculated by continuously changing the absolute value of the operation speed at the tip of the robot arm so that the absolute values of the speeds at the two locations coincide with each other. Control device.