Robot control device, robot control method, and storage medium

Abstract

The present application provides a robot control device, a robot control method, and a storage medium that can set control parameters that conform to each work content. The robot control device has a control section that causes a robot to perform work, and in the robot control device, the control section determines a control parameter based on a table that defines a correspondence relationship between a work content of the work performed by the robot and a level of the control parameter of the robot, in which table, as control parameters, there are included an instruction tracking property that indicates a tracking property of the robot with respect to a position instruction, and a motion end determination reference that indicates a reference for determining an end of a motion of the robot, and the level of the instruction tracking property and the level of the motion end determination reference can be changed separately.

Description

Technical Field

[0001] This invention relates to robot control devices, robot control methods, and storage media. Background Technology

[0002] Industrial robots need to perform actions based on the tasks assigned by each operator. However, the tasks vary from operator to operator; therefore, the parameters used to make the robot move are generally set as initial values ​​to universal values ​​that can broadly handle all work areas (the robot's range of motion). While setting these universal parameters has the advantage of allowing the robot to move uniformly across all work areas, it conversely makes it difficult to improve the accuracy of robot movements in a specific work area, or to achieve localized improvements in accuracy. In view of this, Patent Document 1 discloses a robot control device capable of setting dedicated parameters for specific work areas.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2009-142903

[0004] However, depending on the type of task the robot performs, the control parameters required by the operator, such as prioritizing speed or vibration reduction, will vary. Therefore, the robot control device needs to be set with control parameters that meet the operator's expectations. This is difficult to address in the robot control device of Patent Document 1. Summary of the Invention

[0005] The robot control device of the present invention is characterized in that it has a control unit for causing the robot to perform operations, wherein in the robot control device,

[0006] The control unit determines the control parameters based on a table that specifies the correspondence between the task content of the robot and the levels of the robot's control parameters.

[0007] The table includes control parameters such as command tracking performance, which represents the robot's tracking ability in response to position commands, and action termination determination criteria, which represent the criteria for determining the end of the robot's action.

[0008] It is possible to change the level of instruction tracking and the level of the action end determination criterion respectively.

[0009] The robot control method of the present invention is characterized in that the control parameters are determined based on a table that specifies the correspondence between the tasks performed by the robot and the levels of the robot's control parameters.

[0010] The table includes control parameters such as command tracking performance, which represents the robot's tracking ability in response to position commands, and action termination determination criteria, which represent the criteria for determining the end of the robot's action.

[0011] It is possible to change the level of instruction tracking and the level of the action end determination criterion respectively.

[0012] The robot control program of the present invention is characterized in that the control parameters are determined based on a table that specifies the correspondence between the tasks performed by the robot and the levels of the robot's control parameters.

[0013] The table includes control parameters such as command tracking performance, which represents the robot's tracking ability in response to position commands, and action termination determination criteria, which represent the criteria for determining the end of the robot's action.

[0014] It is possible to change the level of instruction tracking and the level of the action end determination criterion respectively. Attached Figure Description

[0015] Figure 1 This is a perspective view showing the overall configuration of the robot system according to the preferred embodiment.

[0016] Figure 2 This is a diagram showing the table.

[0017] Figure 3 It is a graph showing the speed of the control parameters.

[0018] Figure 4 It is a graph that shows the instruction tracking of control parameters.

[0019] Figure 5 It is a graph showing the criteria for determining the end of the action of the control parameters.

[0020] Figure 6 It is a graph showing the criteria for determining the end of the action of the control parameters.

[0021] Explanation of reference numerals in the attached figures

[0022] 1…robot system, 2…robot, 21…base, 22…robotic arm, 221…first arm, 222…second arm, 231…drive unit, 232…drive unit, 233…drive unit, 234…drive unit, 24…working head, 241…spline nut, 242…ball screw nut, 243…spline shaft, 25…end effector, 26…payload, 27…inertial sensor, 3…robot control unit, 30…control unit, 4…display device, 5…input device, C…controller, E…encoder, J1…first axis, J2…second axis, J3…third axis, M…motor, P0…current position, P1…destination position, Pt…robot control program, Sd…position command, T…table, W…object, Δt…operation time, Δt1…time, Δt2…time, Δp…difference. Detailed Implementation

[0023] The robot control device, robot control method, and robot control program of the present invention will now be described in detail based on the preferred embodiments shown in the accompanying drawings.

[0024] Figure 1 This is a perspective view showing the overall configuration of the robot system according to the preferred embodiment. Figure 2 This is a diagram showing the table. Figure 3 It is a graph showing the speed of the control parameters. Figure 4 It is a graph that shows the instruction tracking of control parameters. Figure 5 It is a graph showing the criteria for determining the end of the action of the control parameters. Figure 6 It is a graph showing the criteria for determining the end of the action of the control parameters.

[0025] Figure 1 The robot system 1 shown has a robot 2, a robot control device 3 that controls the drive of the robot 2, and a display device 4 and an input device 5 connected to the robot control device 3.

[0026] Robot 2

[0027] Robot 2 is a horizontal articulated robot (SCARA robot), used for example in various operations such as holding, transporting, assembling, and inspecting workpieces such as electronic components. However, the application of Robot 2 is not particularly limited. Furthermore, Robot 2 is not limited to a horizontal articulated robot; for example, it could also be a 6-axis vertical articulated robot.

[0028] Robot 2 has a base 21 fixed to the ground and a robotic arm 22 connected to the base 21. The robotic arm 22 has: a first arm 221, the base of which is connected to the base 21 and can rotate relative to the base 21 about a first axis J1; and a second arm 222, the base of which is connected to the front end of the first arm 221 and can rotate relative to the first arm 221 about a second axis J2 parallel to the first axis J1. Furthermore, a working head 24 is provided at the front end of the second arm 222.

[0029] The working head 24 includes a spline nut 241 and a ball screw nut 242 coaxially disposed at the front end of the second arm 222, and a spline shaft 243 inserted into the spline nut 241 and the ball screw nut 242. The spline shaft 243 can rotate relative to the second arm 222 about a third axis J3, which serves as its central axis, and can move up and down in the direction along the third axis J3. It should be noted that the third axis J3 is parallel to the first axis J1 and the second axis J2.

[0030] A load 26 for mounting an end effector 25 is provided at the lower end of the spline shaft 243. There are no particular limitations on the end effector 25 mounted on the load 26, and it can be appropriately selected according to the work content. However, in this embodiment, a gripper that adsorbs and holds the object W is used.

[0031] In addition, an inertial sensor 27 is configured in the payload 26, which can detect the acceleration and angular velocity applied to the front end of the robotic arm 22.

[0032] Furthermore, a drive device 231 is provided within the base 21, enabling the first arm 221 to rotate relative to the base 21 about a first axis J1. Additionally, the second arm 222 is provided with: a drive device 232 for rotating the second arm 222 relative to the first arm 221 about a second axis J2; a drive device 233 for rotating the spline nut 241 and causing the spline shaft 243 to rotate about a third axis J3; and a drive device 234 for rotating the ball screw nut 242 and causing the spline shaft 243 to move up and down along the third axis J3.

[0033] Each drive unit 231, 232, 233, and 234 has a motor M as a drive source, a controller C for controlling the drive of the motor M, and an encoder E for detecting the rotation of the motor M. The motor M is driven by servo control that feeds back the output of the encoder E.

[0034] Robot control device 3

[0035] The robot control device 3 has a control unit 30, which controls the drive of the drive devices 231, 232, 233, 234 and the end effector 25 individually based on position commands Sd from a host computer (not shown), so that the robot 2 can perform a predetermined task.

[0036] The robot control device 3, for example, is a computer, having a processor for processing information, a memory connected to the processor in a communicative manner, and an external interface for connecting to external devices. The memory stores a robot control program Pt that can be executed by the processor. The processor reads the robot control program Pt stored in the memory and executes the control method described below.

[0037] Here, in order for robot 2 to perform actions, it is necessary to pre-set various control parameters required for robot 2's control, such as the robot arm 22's range of motion, speed, command tracking performance, and action termination criteria. In the field of robotics, manufacturers typically set these control parameters appropriately at the factory, considering factors such as safety and operability. However, the tasks performed by robot 2 vary from operator to operator, and the optimal control parameters also differ depending on the task. Therefore, manufacturers generally set universal control parameters as initial values ​​to ensure broad applicability to various tasks.

[0038] However, the commonly used control parameters may not be accurate enough to meet the operator's requirements. Therefore, the robot control device 3 can store the control parameters in table T and change them according to the operator's request. This allows the robot 2 to perform actions using control parameters that meet the operator's expectations.

[0039] like Figure 2 As shown, Table T includes the conveying operation of the object W and the assembly operation of the object W as the work content. Thus, by including both conveying and assembly operations as work content, most of the tasks performed by the robot 2 can be covered. Therefore, it becomes a highly convenient robot control device 3. It should be noted that there are no particular limitations on the assembly operation; however, examples include operations such as assembling the object W to other components through threaded fixing, screw engagement, or fitting; operations such as forming holes in the object W using a drill; and operations such as deforming the object W through pressing or bending.

[0040] Furthermore, Table T lists the conveying operations as including a first conveying operation that conveys an object W with a weight less than a predetermined value, and a second conveying operation that conveys an object W with a weight greater than the predetermined value. This allows for detailed conveying operations and easy setting of control parameters specific to the operator's tasks. It should be noted that the predetermined weight value can be set based on the characteristics of the robot 2, particularly its conveyable weight; for example, it can be set to 50% of the conveyable weight.

[0041] Furthermore, Table T specifies appropriate control parameters for the first and second conveying operations and assembly. These control parameters, including speed, command tracking accuracy, and action completion criteria, are selected from three levels: "high," "medium," and "low." In other words, Table T defines the correspondence between the operation content and the control parameter levels. However, the number of levels is not specifically limited; it can be two, four or more, or even virtually no levels.

[0042] The speed included in the control parameters represents the speed of the robotic arm 22, such as... Figure 3 As shown, the higher the speed level, the faster the robotic arm 22 moves. Therefore, the higher the speed level, the shorter the time Δt1 it takes for the robot 2 to travel from its current position P0 to its destination position P1. It should be noted that the speed includes at least one of absolute speed, acceleration, deceleration, angular acceleration, and angular deceleration.

[0043] Furthermore, command tracking performance refers to the tracking performance of robot 2 for position command Sd, such as... Figure 4 As shown, the higher the level, the better the tracking performance of robot 2 for position command Sd. Therefore, the higher the level of command tracking performance, the smaller the difference Δp between the position based on position command Sd and the actual position during movement to the target position P1, and the shorter the time Δt1 for robot arm 22 to reach the target position P1 from the current position P0.

[0044] Furthermore, the action end determination criterion refers to the standard for determining the end of an action of robot 2. The action is determined to be complete if the amplitude of the residual vibration (hereinafter also referred to as "residual vibration") after the robotic arm 22 reaches the target position P1 is below a predetermined value. That is, if... Figure 5 As shown, the higher the level of the action end judgment benchmark, the smaller the amplitude, and the longer the time Δt2 from when the robotic arm 22 reaches the target position P1 until the judgment of action end is obtained.

[0045] There are no particular limitations on the method for detecting the actual position and residual vibration of the robotic arm 22. For example, detection can be performed based on the output of the inertial sensor 27. Furthermore, detection can be performed based on the output of the encoder E provided by the drive units 231, 232, 233, and 234. With such detection methods, the actual position and residual vibration of the robotic arm 22 can be easily and accurately detected.

[0046] Thus, the operation time Δt of one action of robot 2 is determined by the sum of the time Δt1 from the current position P0 to the destination position P1, and the time Δt2 from the arrival at the destination position P1 to the determination that the action is completed. That is, Δt = Δt1 + Δt2. It should be noted that the higher the speed and command tracking level, the faster robot 2 becomes, and therefore the time Δt1 becomes shorter. On the other hand, due to the increase in residual vibration, there is a tendency for time Δt2 to become longer. Conversely, the lower the speed and command tracking level, the slower robot 2 becomes, and therefore the time Δt1 becomes longer. On the other hand, due to the decrease in residual vibration, there is a tendency for time Δt2 to become shorter.

[0047] It should be noted that the criterion for determining the end of an action is not limited to the amplitude of the residual vibration mentioned above. The action can also be considered complete when the difference Δp between the target position P1 and the actual position is below a predetermined value. That is, if... Figure 6 As shown, the higher the level of the action end judgment benchmark, the smaller the difference Δp and the longer the operation time Δt. This detection method can also easily and accurately detect the actual position and residual vibration of the robotic arm 22.

[0048] Depending on the task content, there may be situations where task time Δt is prioritized over positional accuracy. In such cases, it is preferable to increase the levels of speed and command tracking performance while decreasing the level of the action termination determination criterion. Furthermore, depending on the task content, there may be situations where positional accuracy is prioritized over task time Δt. In such cases, it is preferable to decrease the levels of speed and command tracking performance while increasing the level of the action termination determination criterion. Thus, the optimal control parameters differ depending on the task content.

[0049] In the first conveying operation, high operating speeds are often required. Therefore, increasing the levels of both speed and command tracking is effective. This shortens the operation time Δt, allowing for repeated conveying operations at short intervals. Furthermore, in the first conveying operation, high positional accuracy is often required both when holding the object W and when placing the held object W. Therefore, it is effective to improve the level of the action completion determination criterion while avoiding excessively long operation times Δt. Through the above processing, as... Figure 2As shown, in the control parameters of the first conveying operation, the initial values ​​are "high" for speed, "medium" for command tracking, and "medium" for action end determination criteria.

[0050] In the second conveying operation, since the object W is heavier than in the first conveying operation, high positional accuracy is often not required. Therefore, it is preferable to lower the level of the action completion determination criterion to shorten the operation time Δt. Furthermore, since the impact of residual vibration is small, it is preferable to increase the levels of speed and command tracking to shorten the operation time Δt. Through the above processing, as... Figure 2 As shown, in the control parameters of the second conveying operation, the initial values ​​are set as "high" for speed, "high" for command tracking, and "low" for action end judgment criteria.

[0051] In assembly operations, positional deviations directly lead to a decrease in assembly accuracy, thus requiring high command tracking performance in many cases. Therefore, improving the level of command tracking performance is effective. This reduces the difference Δp between the position command Sd and the actual position, enabling assembly operations with excellent accuracy. Furthermore, in assembly operations, reducing the speed level and making robot 2 move slowly to improve assembly accuracy is effective. Additionally, in assembly operations, increasing the level of the action completion determination criterion and performing the next action with less residual vibration is effective. Through the above processing, such as... Figure 2 As shown, in the control parameters of the assembly operation, the initial values ​​are set as "low" speed, "high" command tracking, and "high" action end judgment benchmark.

[0052] The above explains Table T. The robot control device 3 determines control parameters based on Table T. Typically, Table T is compared with the task content received from the operator to determine the control parameters. The robot control device 3 displays a graphical interface on a display device 4 such as a monitor, through which the operator selects the task content based on input from the input device 5. When the task content is received from the operator via the graphical interface, the robot control device 3 sets the control parameters of the selected task content as the control parameters of the robot 2.

[0053] However, there are no particular limitations on the method for determining the control parameters. For example, the robot control device 3 can also select the task content based on the motion program created by the operator, and set the control parameters of the selected task content as the control parameters of the robot 2.

[0054] Furthermore, regarding conveying operations, for example, one of the first and second conveying operations can be selected based on the weight of the object W input by the operator through the graphical interface, and the control parameters of the selected operation can be set as the control parameters of the robot 2. Alternatively, the robot 2 can actually convey the object W, and the weight of the object W can be measured based on the output of the inertial sensor 27 at this time. Based on the measurement result, one of the first and second conveying operations can be selected, and the control parameters of the selected operation can be set as the control parameters of the robot 2.

[0055] According to this robot control device 3, control parameters suitable for each task can be set. Therefore, each task can be performed efficiently. Furthermore, by simply selecting a target task or a task close to the target task from a set of pre-set tasks, control parameters suitable for that task are automatically set. Therefore, even operators with limited knowledge of robot control can easily set control parameters suitable for the task.

[0056] As mentioned earlier, in the robot control device 3, preferred control parameters are preset for each of the first and second conveying operations and the assembly operation. However, depending on the operator, the various items of the control parameters may be fine-tuned to achieve the required operation content. Therefore, in the robot control device 3, for each operation content stored in Table T according to the request from the operator, the levels of the various items of the control parameters, namely speed, command tracking performance, and operation completion judgment criteria, can be changed to any one of "high", "medium", or "low".

[0057] There are no particular limitations on the method of modification; however, for example, the operator can use input device 5 to request changes to the level of each item of the control parameters through the graphical interface displayed on display device 4. The robot control device 3 changes the level of each item according to the operator's request. With this configuration, control parameters specific to the operator's work content can be set. Therefore, the work content required by the operator can be achieved more reliably.

[0058] In particular, in this embodiment, the control parameters are selected from three levels: "high," "medium," and "low." Therefore, even operators with limited knowledge of robot control can intuitively and easily change the control parameters. It should be noted that the control parameters can also be changed automatically by the robot control device 3 based on the operation results of the robot 2.

[0059] The robot system 1 has been described above. This robot system 1 includes a robot control device 3 with a control unit 30 that enables the robot 2 to perform operations. Furthermore, the control unit 30 determines the control parameters based on a table T that defines the correspondence between the content of the work performed by the robot 2 and the levels of control parameters for the robot 2. In addition, the table T includes, as control parameters, command tracking performance, representing the robot 2's tracking ability in response to the position command Sd, and an action end determination criterion, representing the criterion for determining the end of the robot 2's action. Furthermore, the level of command tracking performance and the level of the action end determination criterion can be changed separately.

[0060] Therefore, each task included in Table T can be performed with appropriate control parameters. Furthermore, the level of instruction tracking and the level of action completion determination criteria can be changed, thus allowing control parameters to be specific to the operator's task content. Therefore, the task content required by the operator can be achieved more reliably.

[0061] Furthermore, as mentioned earlier, Table T includes the speed of robot 2 as a control parameter, allowing for the adjustment of speed levels. This enables the setting of control parameters specific to the operator's tasks. Consequently, the operator's required tasks can be achieved more reliably.

[0062] Furthermore, as mentioned earlier, Table T lists the tasks as including the transport of object W and the assembly of object W. This covers most of the tasks performed by robot 2. Therefore, it becomes a highly convenient robot control device 3.

[0063] Furthermore, as mentioned earlier, Table T includes, as a conveying operation, a first conveying operation that conveys objects with a weight less than a predetermined value, and a second conveying operation that conveys objects with a weight greater than the predetermined value. This allows for the refinement of the conveying operations and easy setting of control parameters specific to the operator's tasks. It should be noted that the predetermined weight value can be set based on the characteristics of the robot 2, particularly its conveyable weight; for example, it can be set to 50% of the conveyable weight.

[0064] Furthermore, as mentioned earlier, the action end determination criterion is based on the difference Δp between the target position P1 according to the position command Sd and the actual position. The higher the level of the action end determination criterion, the smaller the difference Δp. Therefore, conveying and assembly operations can be performed separately based on appropriate control parameters.

[0065] Furthermore, as mentioned earlier, the action termination determination criterion is based on the amplitude of residual vibration; the higher the level of the action termination determination criterion, the smaller the amplitude. Therefore, conveying and assembly operations can be performed separately according to appropriate control parameters.

[0066] Furthermore, as mentioned earlier, the robot control method determines the control parameters based on Table T, which specifies the correspondence between the tasks performed by robot 2 and the levels of control parameters for robot 2. Table T includes, as control parameters, command tracking performance (representing the robot 2's ability to track position command Sd) and an action end determination criterion (representing the basis for determining the end of robot 2's action). Additionally, the levels of command tracking performance and action end determination criterion can be changed separately.

[0067] Therefore, each task included in Table T can be performed with appropriate control parameters. Furthermore, the level of instruction tracking and the level of action completion determination criteria can be changed, thus allowing control parameters to be specific to the operator's task content. Therefore, the task content required by the operator can be achieved more reliably.

[0068] Furthermore, as mentioned earlier, the robot control program Pt determines the control parameters based on Table T, which specifies the correspondence between the tasks performed by robot 2 and the levels of control parameters for robot 2. Table T includes, as control parameters, command tracking performance (representing the robot 2's ability to track position command Sd) and an action end determination criterion (representing the basis for determining the end of robot 2's action). Additionally, the levels of command tracking performance and action end determination criterion can be changed separately.

[0069] Therefore, each task included in Table T can be performed individually using appropriate control parameters. Furthermore, the level of instruction tracking and the level of action completion determination criteria can be changed, allowing control parameters to be set specifically for the operator's task content. Thus, the task content required by the operator can be achieved more reliably.

[0070] The robot control device, robot control method, and robot control program of the present invention have been described above based on the illustrated embodiments. However, the present invention is not limited thereto, and the configuration of each part can be replaced with any configuration having the same function. Furthermore, other arbitrary components can be added to the present invention.

Claims

1. A robot control device, characterized in that, The robot control device has a control unit that enables the robot to perform operations. The control unit determines the control parameters based on a table that specifies the correspondence between the task content of the robot and the levels of the robot's control parameters. The table includes control parameters such as command tracking performance, which represents the robot's tracking ability in response to position commands, and action termination determination criteria, which represent the criteria for determining the end of the robot's action. It is possible to change the level of instruction tracking and the level of the action end determination criterion respectively.

2. The robot control device according to claim 1, characterized in that, The table also includes the robot's speed as one of the control parameters. It is possible to change the speed level.

3. The robot control device according to claim 1 or 2, characterized in that, In the table, the work content includes the transportation of the object and the assembly of the object.

4. The robot control device according to claim 3, characterized in that, The table includes, as the conveying operation, a first conveying operation that conveys objects with a weight less than a predetermined weight value, and a second conveying operation that conveys objects with a weight greater than the predetermined weight value.

5. The robot control device according to claim 1, characterized in that, The criteria for determining the end of the action are based on the difference between the target position according to the position command and the actual position. The higher the level of the action termination determination benchmark, the smaller the difference.

6. The robot control device according to claim 1, characterized in that, The criteria for determining the end of the action are based on the amplitude of the residual vibration. The higher the level of the action end determination criterion, the smaller the amplitude.

7. A robot control method, characterized in that, The control parameters are determined based on a table that defines the correspondence between the tasks performed by the robot and the levels of the robot's control parameters. The table includes control parameters such as command tracking performance, which represents the robot's tracking ability in response to position commands, and action termination determination criteria, which represent the criteria for determining the end of the robot's action. It is possible to change the level of instruction tracking and the level of the action end determination criterion respectively.

8. A storage medium, characterized in that, Store robot control program, The robot control program determines the control parameters based on a table that specifies the correspondence between the tasks performed by the robot and the levels of the robot's control parameters. The table includes control parameters such as command tracking performance, which represents the robot's tracking ability in response to position commands, and action termination determination criteria, which represent the criteria for determining the end of the robot's action. It is possible to change the level of instruction tracking and the level of the action end determination criterion respectively.

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