Patent Publication Number: US-2020282568-A1

Title: Robot control device and robot system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a bypass continuation of PCT Application No. PCT/JP2018/042520, filed Nov. 16, 2018, which claims priority to JP 2017-227113, filed Nov. 27, 2017, both of which are incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present application relates to a robot control device and a robot system. 
     BACKGROUND ART 
     Conventionally, robot control devices which control a robot aim to demonstrate a capability of a motor to its maximum extent, no matter what point an acceleration start point and a deceleration end point of the robot may be. The robot control device may do this to shorten an operating time. Moreover, when a teaching point memory means receives a move command, the robot control device analyzes the move command and determines from which point to which point the robot is to be moved. 
     However, such conventional robot control devices operate the robot within an allowable range that is predefined according to a load to be applied to the robot. Therefore, a tact time cannot be fully shortened. 
     SUMMARY 
     In order to solve the above-described problem, a robot control device according to one aspect of the present application configured to control a robot is provided. The robot control device controls the robot selectively in a normal operating mode in which the robot is operated within an allowable range defined beforehand according to load applied to the robot and an overdrive mode in which the robot is operated at high speed without operation of the robot being limited to the allowable range. The robot control device operates the robot at high speed in the overdrive mode by interlockingly changing magnification scales of a plurality of parameters defined beforehand that may specify an operating speed of the robot, based on an overdrive magnification scale defined beforehand about a degree of the high-speed operation in the overdrive mode. 
     In order to solve the described problem, a robot system according to another aspect of the present application is provided. The robot system includes a robot control device and a robot controlled by the robot control device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic view illustrating a configuration of a robot system according to an embodiment of the present application. 
         FIG. 2  is a flowchart of a method of operating a robot at high speed executed by the robot system according to an embodiment of the present application. 
         FIG. 3  is a view illustrating an exemplary program process executed by the robot system according to an embodiment of the present application. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Hereinafter, a robot control device and a robot system having the robot control device according to one embodiment of the present application is described with reference to the drawings. Note that the present application is not limited to this embodiment. Moreover, below, throughout the figures, the same reference characters are given to the same or corresponding elements to omit redundant description. 
     (Robot System  10 ) 
       FIG. 1  is a schematic view illustrating a configuration of a robot system according to an embodiment of the present application. As illustrated in  FIG. 1 , a robot system  10  according to this embodiment includes a robot  20  and a robot control device  50  which controls the robot  20 . 
     (Robot  20 ) 
     The robot  20  includes a pedestal  21 , a robotic arm  30  of which a base-end part is coupled to the pedestal  21 , an end effector which is attached to a tip-end part of the robotic arm  30 , and the robot control device  50 . 
     (Robotic Arm  30 ) 
     As illustrated in  FIG. 1 , the robotic arm  30  is an articulated arm having six joints JT 1 -JT 6 , and six links  40   a - 40   f  The six links  40   a - 40   f  are serially coupled to each other through joints JT 1 -JT 6 . 
     A first arm part  31  is comprised of a coupling body of links and joints. In particular, the coupling body of first arm part  31  includes a first joint JT 1 , a first link  40   a , a second joint JT 2 , a second link  40   b , a third joint JT 3 , and a third link  40   c . In detail, the first joint JT 1  couples the pedestal  21  to a base-end part of the first link  40   a  rotatably about an axis extending in the vertical direction. The second joint JT 2  couples a tip-end part of the first link  40   a  to a base-end part of the second link  40   b  rotatably about an axis extending in the horizontal direction. The third joint JT 3  couples a tip-end part of the second link  40   b  to a base-end part of the third link  40   c  rotatably about an axis extending in the horizontal direction. 
     A second arm part  32  is comprised of a coupling body of links and joints. In particular, the coupling body of second arm part  32  includes a fourth joint JT 4 , a fourth link  40   d , a fifth joint JT 5 , a fifth link  40   e , a sixth joint JT 6 , and a sixth link  40   f . In detail, the fourth joint JT 4  couples a tip-end part of the third link  40   c  to a base-end part of the fourth link  40   d  rotatably about an axis extending in the longitudinal direction of the third link  40   c . The fifth joint JT 5  couples a tip-end part of the fourth link  40   d  to a base-end part of the fifth link  40   e  rotatably about an axis extending in a direction perpendicular to the longitudinal direction of the fourth link  40   d . The sixth joint JT 6  rotatably couples a tip-end part of the fifth link  40   e  to a base-end part of the sixth link  40   f  in a twisted fashion. The end effector is attached to a tip-end part of the sixth link  40   f.    
     (Robot Control Device  50 ) 
     Robot control device  50  as disclosed herein may comprise circuitry or processing circuitry which includes general purpose processors, special purpose processors, integrated circuits, ASICs (“Application Specific Integrated Circuits”), conventional circuitry, controllers, and/or combinations thereof which are configured or programmed to perform the disclosed functionality. Processors and controllers are considered processing circuitry or circuitry as they include transistors and other circuitry therein. In this disclosure, any circuitry, units, controllers, or means are hardware carry out or are programmed to perform the recited functionality. The hardware may be any hardware disclosed herein or otherwise known which is programmed or configured to carry out the recited functionality. When the hardware is a processor or controller which may be considered a type of circuitry, the circuitry, means, or units are a combination of hardware and software, the software being used to configure the hardware and/or processor. 
     The robot control device  50  may operate according to a process stored in a memory etc. 
     The robot control device  50  controls the robot  20 , while switching a mode between a normal operating mode, in which the robot  20  is operated within an allowable range defined beforehand according to a load applied to the robot  20 , and an overdrive mode in which the robot  20  is operated at high speed without the operation being limited within the allowable range. 
     Here, in the robot, an allowable range of a current value is defined beforehand for every joint of the robotic arm while considering a certain safety factor so that the current value does not reach a saturation current, regardless of the operation pattern of the robot. Therefore, for example, the “allowable range defined beforehand according to the load applied to the robot  20 ” described above means the allowable range of the current value. 
     The robot control device  50  causes the robot  20  to operate at a high speed in the overdrive mode by interlockingly changing magnification scales of a plurality of parameters defined beforehand which may specify an operating speed of the robot  20 , based on an overdrive magnification scale defined beforehand about a degree of the high-speed operation in the overdrive mode. 
     Here, the plurality of parameters which may specify the operating speed of the robot  20  may include at least any one of an acceleration/deceleration preset value related to the operation of the robot  20 , a limit value of electric current supplied to the robot  20 , and a cutoff frequency of a low-pass filter which is applied to a positional instruction to the robot  20 . The plurality of parameters may be set for every joint of the robotic arm  30 . 
     The overdrive magnification scale may arbitrarily be set within a given range, or a plurality of overdrive magnification scales may be defined beforehand differently in a stepped fashion and one may be selected from the magnification scales. As the overdrive magnification scale increases, it is possible to set the acceleration/deceleration preset value related to the operation of the robot  20 , the limit value of the current supplied to the robot  20 , and the cutoff frequency of the low-pass filter which is applied to the positional instruction to the robot  20  larger. That is, there is a positive correlation between the overdrive magnification scale, and the acceleration/deceleration preset value related to the operation of the robot  20 , the limit value of the current supplied to the robot  20 , and the cutoff frequency of the low-pass filter which is applied to the positional instruction to the robot  20 . 
     (Notification of Influence on a Life of the Robot) 
     The robot control device  50  may provide a notification, of information about an influence on the life of the robot  20 , when operating the robot  20  at high speed in the overdrive mode. The mode of the notification is not limited in particular, and, for example, the robot control device  50  may provide such a notification by controlling an output of characters or an image on a display unit, or an output of audio from a speaker. Alternatively, the robot control device  50  may provide the notification by controlling an output light from a light source, such as a light emitting diode (LED). 
     (How to Operate Robot at High Speed) 
     Below, one example of a method of operating the robot at high speed, which is executed by the robot system described above is described mainly based on  FIG. 2 .  FIG. 2  is a flowchart of a method of operating the robot at high speed, executed by the robot system according to the present application. 
     First, the robot control device  50  confirms an input of an overdrive magnification scale (Step S 1 ). If the robot control device  50  confirms the input of the overdrive magnification scale (“YES” at Step S 1 ), the robot control device  50  then changes the magnification scales of the plurality of parameters interlockingly based on the confirmed overdrive magnification scale (Step S 2 ). Here, as described above, the plurality of parameters are parameters which may specify the operating speed of the robot  20 , and, for example, they are the acceleration/deceleration preset value related to the operation of the robot  20 , the limit value of the current supplied to the robot  20 , and the cutoff frequency of the low-pass filter which is applied to the positional instruction to the robot  20 . 
     Next, the robot control device  50  operates the robot  20  at high speed in the overdrive mode based on the plurality of interlockingly changed parameters (Step S 3 ). As described above, in the robot system  10  according to this embodiment, the robot  20  may be operated at high speed. 
     In a case that the robot control device  50  does not confirm the input of the overdrive magnification scale (“NO” at Step S 1 ), the robot control device  50  then operates the robot  20  in a normal operating mode (Step S 4 ). 
     (Example of Program Process) 
       FIG. 3  is a view illustrating an exemplary program process executed by a robot system according to the present application. 
     In this example, a range within which the overdrive magnification scale may be set is 1.00 or more and 2.00 or less. Note that a settable range of the overdrive magnification scale is not limited to this example. That is, the settable range of the overdrive magnification scale may have lower and higher limits higher than 1.00 and smaller than 2.00, or higher than 2.00. Moreover, the lower limit and the higher limit may be values of the first place of decimals, or may be of the third or more place of decimals, or may be an integer of 1 or larger. Further, as described above, without limiting the plurality of overdrive magnification scales being defined beforehand in the stepped fashion and one being set from the magnification scales, the overdrive magnification scale may arbitrarily be set within a given range. 
     In this example, the overdrive magnification scale is set as 1.2 in advance by an auxiliary function or a monitor instruction which may set an entire operation of the robot  20 . Thus, by setting the overdrive magnification scale, as described above, the robot control device  50  interlockingly changes the magnification scales of the plurality of parameters defined beforehand, which may specify the operating speed of the robot  20  (e.g., the acceleration/deceleration preset value related to the operation of the robot  20 , the limit value of the current supplied to the robot  20 , and the cutoff frequency of the low-pass filter which is applied to the positional instruction to the robot  20 ) based on the overdrive magnification scale. Thus, the robot control device  50  operates the robot  20  at high speed in the overdrive mode. In detail, the operation is as follows. 
     First, the robot control device  50  operates a tip-end part of the robotic arm  30  at high speed based on a command of “1. JMOVE #a” with the overdrive magnification scale of 1.2 to a teaching point #a by using an interpolation of each axis. Here, the each axis interpolation refers to an operation of each joint of the robotic arm  30  by a specified angle, and therefore, does not take an orbit of the tip-end part of the robotic arm  30  into consideration. 
     Next, the robot control device  50  changes the overdrive magnification scale to 1.5 from 1.2 based on a command of “2. OVERDRIVE 1.5”. The robot control device  50  interlockingly changes the magnification scales of the plurality of parameters defined beforehand which may specify the operating speed of the robot  20 , based on the overdrive magnification scale of 1.5. Here, since the overdrive magnification scale is changed to 1.5 from 1.2, the magnification scales of the plurality of parameters are interlockingly changed so that the robot  20  may be operated at a higher speed than before the change. 
     Moreover, the robot control device  50  operates the tip-end part of the robotic arm  30  at high speed with the overdrive magnification scale of 1.5 to a teaching point #b by a straight line interpolation based on a command of “3. LMOVE #b”. Here, the straight line interpolation refers to a straight movement of the tip-end part of the robotic arm  30  by collaborating the joints of the robotic arm  30 . 
     Further, the robot control device  50  operates the tip-end part of the robotic arm  30  at high speed with the overdrive magnification scale of 1.5 to a teaching point #c by the straight line interpolation based on a command of “4. LMOVE #c”. 
     Next, the robot control device  50  changes the overdrive magnification scale to 1 from 1.5 based on a command of “5. OVERDRIVE 1”. That is, the robot control device  50  changes the robot  20  from overdrive mode to the normal operating mode based on the command. 
     Moreover, the robot control device  50  operates the tip-end part of the robotic arm  30  in the normal operating mode to a teaching point #d by the straight line interpolation based on a command of “6. LMOVE #d”. 
     Further, the robot control device  50  changes the overdrive magnification scale from 1 to 1.2 set in advance by the auxiliary function or the monitor instruction, based on a command of “7. OVERDRIVE”. 
     Finally, the robot control device  50  operates the tip-end part of the robotic arm  30  at high speed with the overdrive magnification scale of 1.2 to a teaching point #e by the straight line interpolation based on a command of “8. LMOVE #e”. 
     As described above, the robot control device  50  may control the robot  20  based on the program process illustrated in  FIG. 3 . 
     As described above, since the overdrive magnification scale is changed for every work performed by the robot  20 , the robot  20  may be controlled efficiently, for example, by setting the overdrive magnification scale smaller when holding a workpiece, and setting the overdrive magnification scale larger when not holding the workpiece. Similarly, the robot  20  may be controlled efficiently by setting the overdrive magnification scale larger when the robotic arm  30  is folded and a distance between its tip-end part and its base-end part is closer (i.e., when the inertia is smaller), and setting the overdrive magnification scale smaller when the robotic arm  30  is extended and the distance between the tip-end part and the base-end part is larger (i.e., when the inertia is larger). 
     Effects 
     The conventional robot control device operates a robot within an allowable range defined beforehand according to the load applied to the robot. For example, the allowable range of a current value is defined beforehand for every joint of a robotic arm while considering a certain safety factor so that the current value does not reach a saturation current, regardless of the operation pattern of the robot. However, depending on an actual work situation, the allowable range may not be appropriate, and therefore, there are cases where it does not cause any problem even if the robot is operated at high speed without the operation being limited to the allowable range. Moreover, there are demands of operating the robot at high speed without the operation being limited to the allowable range, even if the certain safety factor is reduced to sacrifice the life of the robot to some extent. 
     In order to solve such a problem, the robot control device  50  according to this application controls the robot  20  in the overdrive mode in which the robot  20  is operated at high speed without the operation being limited to the allowable range, in addition to the normal operating mode in which the robot  20  is operated within the allowable range defined beforehand according to the load applied to the robot  20 . 
     In detail, the robot control device  50  according to this application operates the robot  20  at high speed in the overdrive mode by interlockingly changing the magnification scales of a plurality of parameters defined beforehand which may specify the operating speed of the robot  20  based on the overdrive magnification scale defined beforehand about the degree of high-speed operation in the overdrive mode. As a result, the robot control device  50  according to this application fully shortens the tact time by operating the robot  20 , without the operation being limited to the allowable range defined beforehand according to the load applied to the robot  20 . Additionally, the robot control device  50  may fully shorten the tact time by operating the robot  20  at high speed, without the operation being limited to the allowable range defined beforehand according to the load applied to the robot. 
     The plurality of parameters may include at least any one of an acceleration/deceleration preset value according to operation of the robot, a limit value of electric current supplied to the robot, and a cutoff frequency of a low-pass filter that is applied to a positional instruction to the robot. 
     Moreover, since the overdrive magnification scale may arbitrarily be set within the given range. The plurality of overdrive magnification scales may be defined beforehand differently in the stepped fashion. One overdrive magnification scale may be selected from the plurality of magnification scales and set as the overdrive magnification scale. Additionally, the degree of high-speed operation may be changed according to the work situation of the robot  20 . Therefore, devices in accordance with the present application may flexibly address the demand of a user. With these configurations, the overdrive magnification scale may be changed according to a work situation of the robot. 
     Further, since the robot control device  50  notifies the information on the influence to the life of the robot  20 , when operating the robot  20  at high speed in the overdrive mode, it becomes possible to operate the robot  20  at high speed, without the operation being limited to the allowable range defined beforehand according to the load applied to the robot  20 , while grasping the influence to the life of the robot  20 . 
     It is apparent for a person skilled in the art that many improvements and other embodiments of the present application are possible from the above description. Therefore, the above description is to be interpreted only as illustration, and it is provided in order to teach a person skilled in the art the best mode to implement the present application. The details of the structures and/or the functions may be changed substantially, without departing from the spirit of the present application. 
     DESCRIPTION OF REFERENCE CHARACTERS 
     
         
         
           
               10  Robot System 
               20  Robot 
               21  Pedestal 
               30  Robotic Arm 
               31  First Arm Part 
               32  Second Arm Part 
               40   a  First Link 
               40   b  Second Link 
               40   c  Third Link 
               40   d  Fourth Link 
               40   e  Fifth Link 
               40   f  Sixth Link 
               50  Robot Control Device 
             JT 1  First Joint 
             JT 2  Second Joint 
             JT 3  Third Joint 
             JT 4  Fourth Joint 
             JT 5  Fifth Joint 
             JT 6  Sixth Joint