Method for controlling a robot

Abstract

A control method of a robot is provided to help avoid shortening of the life of the robot due to resonance. In the control method of the robot of the invention, the robot has a rotation shaft that constitutes a joint portion, and the control method includes: a first planning step of performing motion planning of the robot based on a motion instruction to obtain a rotation speed of the rotation shaft; a determination step of determining whether the rotation speed of the rotation shaft obtained by the first planning step is in a resonance region; and a change step of performing the motion planning of the robot again to avoid the resonance region for the obtained rotation speed of the rotation shaft when it is determined in the determination step that the rotation speed of the rotation shaft is in the resonance region.

Description

Technical Field

[0001] This invention relates to a method for controlling a robot. Background Technology

[0002] When the robot moves at a speed that falls within the resonance range of the rotational speed of the shafts that make up its joints, the robot will vibrate significantly.

[0003] Therefore, when a robot continuously performs actions at a speed that falls within the resonance region of the rotating shaft, the robot's lifespan is easily shortened due to resonance.

[0004] Furthermore, when the robot vibrates significantly, the objects it is handling (such as the workpieces being moved) may become misaligned or damaged.

[0005] To address the aforementioned issues, in previous robot control methods, when receiving motion commands from a host device, if the rotational speed of the shaft contained in the motion command falls within the resonance region, a speed command to avoid the resonance region will be issued to the robot.

[0006] However, when the rotational speed of the axis included in the motion command is outside the resonance region (e.g., greater than the maximum value of the resonance region), but the actual rotational speed of the axis does not reach the rotational speed of the axis included in the motion command due to the small amount of robot motion, or when the robot has multiple axes that move simultaneously, and the axis involved in the motion command coordinates with other axes to perform the motion, such as... Figure 4 As shown, the axis involved in the motion command may still rotate at the speed within the resonance region. Therefore, the robot may still have a shortened lifespan due to resonance. Summary of the Invention

[0007] The present invention was made in view of the above-mentioned problems, and its purpose is to provide a robot control method that helps to avoid the shortened lifespan of the robot due to resonance.

[0008] To achieve the above objectives, the present invention provides a robot control method, wherein the robot has a rotating shaft constituting a joint, comprising: an initial planning step, wherein the robot's motion is planned according to a motion command to obtain the rotational speed of the rotating shaft; a judgment step, wherein the rotational speed of the rotating shaft obtained through the initial planning step is judged to be within a resonance region; and a modification step, wherein if the rotational speed of the rotating shaft is judged to be within the resonance region in the judgment step, the robot's motion is planned again to ensure that the obtained rotational speed of the rotating shaft avoids the resonance region.

[0009] The robot control method according to the present invention includes: an initial planning step, performing robot motion planning according to motion commands to obtain the rotational speed of a rotating shaft; a judgment step, judging whether the rotational speed of the rotating shaft obtained through the initial planning step is within the resonance region; and a modification step, in which, if the judgment step determines that the rotational speed of the rotating shaft is within the resonance region, the robot motion planning is performed again so that the obtained rotational speed of the rotating shaft avoids the resonance region. Therefore, even if the robot's motion is small or the rotating shaft involved in the motion command is coordinated with other rotating shafts to perform the motion, the rotating shaft involved in the motion command can be prevented from rotating at a speed within the resonance region, thereby preventing the robot's lifespan from being shortened due to resonance.

[0010] Furthermore, in the robot control method of the present invention, it is preferable that when the rotational speed of the shaft is determined to be within the resonance region in the determination step, the robot's motion planning is performed again in the change step so that the obtained rotational speed of the shaft is less than the minimum value of the resonance region.

[0011] According to the robot control method of the present invention, in the change step, when it is determined in the judgment step that the rotational speed of the shaft is in the resonance region, the robot's motion planning is performed again so that the obtained rotational speed of the shaft is less than the minimum value of the resonance region. Therefore, the robot's lifespan can be shortened more effectively due to resonance.

[0012] Furthermore, in the robot control method of the present invention, it is preferable that the rotating shaft is provided with multiple shafts.

[0013] Furthermore, in the robot control method of the present invention, the robot preferably has: a base portion; an arm portion, the base end of which is rotatably connected to the base portion via a first pivot serving as the pivot; and a hand portion, the hand portion being rotatably connected to the front end of the arm portion via a second pivot serving as the pivot.

[0014] (Invention Effects)

[0015] According to the present invention, the robot control method includes: an initial planning step, which performs robot motion planning according to motion commands to obtain the rotational speed of the shaft; a judgment step, which judges whether the rotational speed of the shaft obtained through the initial planning step is within the resonance region; and a modification step, which, if the judgment step determines that the rotational speed of the shaft is within the resonance region, performs robot motion planning again so that the obtained rotational speed of the shaft avoids the resonance region. Therefore, even if the robot's motion is small or the shaft involved in the motion command is coordinated with other shafts to perform the motion, the shaft involved in the motion command can be prevented from rotating at a speed within the resonance region, thereby preventing the robot's lifespan from being shortened due to resonance. Attached Figure Description

[0016] Figure 1 This is a front view illustrating an example of a robot using the robot control method according to an embodiment of the present invention.

[0017] Figure 2 This is a flowchart illustrating an example of a robot control method according to an embodiment of the present invention.

[0018] Figure 3 This is a graph illustrating the suppression of resonance by the robot control method according to an embodiment of the present invention, where the horizontal axis represents time and the vertical axis represents the rotational speed of the shaft constituting the joint.

[0019] Figure 4 This is a graph illustrating how existing robot control methods suppress resonance, where the horizontal axis represents time and the vertical axis represents the rotational speed of the shafts that make up the joints.

[0020] (Symbol Explanation)

[0021] 1. Robot

[0022] 11. Base section

[0023] 12 Arms

[0024] 121 First Arm

[0025] 122 Second Arm

[0026] 13. Hands

[0027] S1 pivot

[0028] S2 pivot

[0029] S3 hinge Detailed Implementation

[0030] Below, in conjunction with Figures 1 to 3 The embodiments of the present invention will be described, wherein, Figure 1 This is a front view schematically illustrating an example of a robot using the robot control method according to an embodiment of the present invention. Figure 2 This is a flowchart illustrating an example of a robot control method according to an embodiment of the present invention. Figure 3 This is a graph illustrating the suppression of resonance by the robot control method according to the embodiments of the invention, where the horizontal axis represents time and the vertical axis represents the rotational speed of the shafts constituting the joints. Figure 4 This is a graph illustrating how existing robot control methods suppress resonance, where the horizontal axis represents time and the vertical axis represents the rotational speed of the shafts that make up the joints.

[0031] For ease of explanation, we define two mutually orthogonal directions as the X direction and the Y direction, and designate one side of the X direction as X1 and the other side of the X direction as X2, and designate one side of the Y direction as Y1 and the other side of the Y direction as Y2.

[0032] (Robot Structure)

[0033] like Figure 1 As shown, robot 1 is a horizontal multi-joint industrial robot, having: a base part 11; an arm part 12, the base end of which is rotatably connected to the base part 11 via a pivot S1; and a hand part 13, which is rotatably connected to the front end of the arm part 12 via a pivot S2.

[0034] Here, as Figure 1 As shown, the arm portion 12 includes a first arm portion 121 and a second arm portion 122. The base end of the first arm portion 121 is rotatably connected to the base portion 11 via a pivot S1 constituting a joint portion. The base end of the second arm portion 122 is rotatably connected to the front end of the first arm portion 121 via a pivot S3 constituting a joint portion. The hand portion 13 is rotatably connected to the front end of the second arm portion 122 via a pivot S2 constituting a joint portion.

[0035] Furthermore, although not shown, robot 1 has motors that drive the arm 12 and hand 13 to rotate, and robot 1 has a control unit and a storage unit, etc. The control unit controls the actions of robot 1, for example, through a program stored in the storage unit.

[0036] (Robot control methods)

[0037] In this embodiment, the control method for robot 1 includes: an initial planning step, in which the robot 1 is planned to obtain the rotational speed of the shaft based on the action command (which can be received from a host device or output from a program in the control unit within robot 1); a judgment step, in which the rotational speed of the shaft obtained through the initial planning step is judged to be within the resonance region; and a modification step, in which the robot 1 is planned again when it is judged in the judgment step to be within the resonance region, so that the obtained rotational speed of the shaft avoids the resonance region.

[0038] Here, the motion planning (including path planning) of robot 1 can be based on data obtained through prior sampling, mapping, or interpolation. Since the motion planning of robot 1 is not the focus of this invention and is a conventional technique in the field, it will not be elaborated on here.

[0039] Below, in conjunction with Figure 2 A specific example of the control method package for robot 1 is provided.

[0040] First, in step ST1, an external host device (not shown) issues an action command (e.g., including target position and action speed).

[0041] Next, in step ST2, the control unit of robot 1 performs motion planning for robot 1 according to the motion instructions received from the host device, and obtains the rotation speed (e.g., the rotation speed in the entire path) of the rotating shaft (e.g., the rotation speed of the rotating shaft S1 to S3).

[0042] Then, in step ST3, the control unit of robot 1 determines whether the rotational speed of the shaft obtained in step ST2 is within the resonance region.

[0043] If it is determined in step ST3 that the rotational speed of the shaft is outside the resonance region, proceed to step ST4 without changing the commanded speed. On the other hand, if it is determined in step ST3 that the rotational speed of the shaft is within the resonance region, proceed to step ST6 and perform motion planning for robot 1 again to ensure that the obtained rotational speed of the shaft avoids the resonance region (e.g., by reducing the rotational speed of the shaft).

[0044] Then, in step ST5, robot 1 performs an action, and finally the action ends.

[0045] (Main effects of this implementation method)

[0046] According to this embodiment, the control method for robot 1 includes: an initial planning step, which performs robot motion planning based on motion commands to obtain the rotational speed of the shaft; a judgment step, which judges whether the rotational speed of the shaft obtained through the initial planning step is within the resonance region; and a modification step, which, if the judgment step determines that the rotational speed of the shaft is within the resonance region, performs robot motion planning again to ensure that the obtained rotational speed of the shaft avoids the resonance region. Therefore, with Figure 4 Different, such as Figure 3 As shown, even if the robot's motion is small or the axis involved in the motion command works in conjunction with other axes, the axis involved in the motion command can be prevented from rotating at a speed within the resonance range, thereby preventing the robot's lifespan from being shortened due to resonance.

[0047] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above embodiments.

[0048] For example, in the above embodiment, the robot 1 with a base 11, an arm 12 and a hand 13 is a horizontal multi-joint industrial robot, but it is not limited to this, and the specific structure of the robot 1 can be appropriately changed as needed.

[0049] Furthermore, in the above embodiments, robot 1 has multiple axes of rotation, but is not limited to this; robot 1 may also have only one axis of rotation.

[0050] Furthermore, in the above embodiments, in the initial planning step, the rotational speed of one shaft or multiple shafts can be obtained. Correspondingly, in the judgment step and the modification step, the rotational speed of one shaft or multiple shafts can be judged and modified.

[0051] It should be understood that within the scope of this invention, the various parts of the embodiments can be freely combined, or the various parts of the embodiments can be appropriately modified or omitted.

Claims

1. A method for controlling a robot, the robot having a pivot constituting a joint, characterized in that, Before causing the robot to move, the following are included: The initial planning step involves planning the robot's motion according to the motion instructions to obtain the rotational speed of the shaft; The judgment step involves determining whether the rotational speed of the shaft obtained through the initial planning step is within the resonance region; and The modification step involves determining that the rotational speed of the shaft is within the resonance region during the judgment step, and then re-planning the robot's motion to ensure that the obtained rotational speed of the shaft avoids the resonance region.

2. The robot control method as described in claim 1, characterized in that, If, in the determination step, it is determined that the rotational speed of the shaft is within the resonance region, in the modification step, the robot's motion planning is performed again so that the obtained rotational speed of the shaft is less than the minimum value of the resonance region.

3. The robot control method as described in claim 1, characterized in that, The rotating shaft has multiple shafts.

4. The robot control method as described in claim 1, characterized in that, The robot has the following characteristics: Base section; An arm portion, the base end of which is rotatably connected to the base portion via a first pivot serving as the pivot; and The hand is rotatably connected to the front end of the arm via a second pivot that serves as the pivot.

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