ROBOT SYSTEM, CONTROL DEVICE, AND CONTROL METHOD

Abstract

To provide a robot system, a control device, and a control method, which can exert high working efficiency.SOLUTION: A robot system includes: a scalar robot which has a robot arm mounted with an end effector thereon and a driving section for driving the robot arm; and a control device which controls the driving section on the basis of a control signal. The control device determines a first case where a prescribed condition is satisfied or a second case where the prescribed condition is not satisfied. In the first case, the control device controls the driving section on the basis of the control signal. In the second case, the control device determines a frequency component to be removed from the control signal using a band-elimination filter, generates a correction control signal by removing the frequency component from the control signal using the band-elimination filter, and controls the driving section on the basis of the generated correction control signal.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a robot system, a control device, and a control method. [Background technology]

[0002] For example, Patent Document 1 describes a robot having an arm with an end effector attached to the tip, which, if the shape of the end effector is large, may cause vibrations in the end effector itself when the robot is operated, reducing work efficiency. Therefore, the natural frequency of the hand when it is gripping a workpiece is measured in advance, and a band-rejection filter is applied to the torque control signal for operating the arm in accordance with the measured natural frequency. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-293638 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, there are cases where not applying a band-stop filter to a specific operation can achieve higher work efficiency, and therefore applying a band-stop filter to all operations may actually decrease work efficiency. [Means for solving the problem]

[0005] The robot system of the present invention includes a SCARA robot including a robot arm to which an end effector is attached and a drive unit that drives the robot arm; A control device that controls the drive unit based on a control signal, The control device includes: Determine whether the case is a first case in which at least one of the following conditions A to E is satisfied, or a second case in which none of the following conditions is satisfied: In the first case, the drive unit is controlled based on the control signal; In the second case, a frequency component to be removed from the control signal is determined using a band-stop filter, the frequency component is removed from the control signal using the band-stop filter to generate a corrected control signal, and the drive unit is controlled based on the generated corrected control signal. Condition A: The system has a first drive mode and a second drive mode in which the upper limit value of the acceleration of the robot arm is lower than that of the first drive mode, and the robot arm is driven in the second drive mode. Condition B: The distance between the center of gravity of the end effector and the tip of the robot arm is equal to or greater than a predetermined value. Condition C: The end point of the robot arm's motion is unknown. Condition D: When the robot arm has an arm and a shaft that moves up and down in a direction vertical to the arm, the amount by which the shaft protrudes from the arm in the vertical direction is equal to or less than a predetermined value. Condition E: The sum of the weight of the end effector and the weight of the workpiece held by the end effector is less than or equal to a predetermined value.

[0006] The control device of the present invention is a control device that controls a SCARA bot including a robot arm to which an end effector is attached and a drive unit that drives the robot arm, based on a control signal, Determine whether the case is a first case in which at least one of the following conditions A to E is satisfied, or a second case in which none of the following conditions is satisfied: In the first case, the drive unit is controlled based on the control signal; In the second case, a frequency component to be removed from the control signal is determined using a band-stop filter, the frequency component is removed from the control signal using the band-stop filter to generate a corrected control signal, and the drive unit is controlled based on the generated corrected control signal. Condition A: The system has a first drive mode and a second drive mode in which the upper limit value of the acceleration of the robot arm is lower than that of the first drive mode, and the robot arm is driven in the second drive mode. Condition B: The distance between the center of gravity of the end effector and the tip of the robot arm is equal to or greater than a predetermined value. Condition C: The end point of the robot arm's motion is unknown. Condition D: When the robot arm has an arm and a shaft that moves up and down in a direction vertical to the arm, the amount by which the shaft protrudes from the arm in the vertical direction is equal to or less than a predetermined value. Condition E: The sum of the weight of the end effector and the weight of the workpiece held by the end effector is less than or equal to a predetermined value.

[0007] A control method of the present invention is a control method for controlling a SCARA robot including a robot arm to which an end effector is attached and a drive unit that drives the robot arm, based on a control signal, the control method comprising the steps of: a frequency component determining step of determining a frequency component to be removed from the control signal using a band rejection filter; a corrected control signal generating step of removing the frequency component from the control signal using the band rejection filter to generate a corrected control signal; The method includes a control step of controlling the drive unit using the control signal in a first case where at least one of the following conditions A to E is satisfied, and controlling the drive unit using the corrected control signal in a second case where none of the following conditions A to E are satisfied. Condition A: The system has a first drive mode and a second drive mode in which the upper limit value of the acceleration of the robot arm is lower than that of the first drive mode, and the robot arm is driven in the second drive mode. Condition B: The distance between the center of gravity of the end effector and the tip of the robot arm is equal to or greater than a predetermined value. Condition C: The end point of the robot arm's motion is unknown. Condition D: When the robot arm has an arm and a shaft that moves up and down in a direction vertical to the arm, the amount by which the shaft protrudes from the arm in the vertical direction is equal to or less than a predetermined value. Condition E: The sum of the weight of the end effector and the weight of the workpiece held by the end effector is less than or equal to a predetermined value.

[0008] A control method of the present invention is a control method for controlling a SCARA robot including a robot arm to which an end effector is attached and a drive unit that drives the robot arm, based on a control signal, the control method comprising the steps of: A determination step is provided for determining whether the present invention is a first case in which at least one of the following conditions A to E is satisfied, or a second case in which none of the following conditions is satisfied: In the second case, further a frequency component determining step of determining a frequency component to be removed from the control signal using a band rejection filter; a corrected control signal generating step of removing the frequency component from the control signal using the band rejection filter to generate a corrected control signal; and a first control step of controlling the drive unit by the corrected control signal. Condition A: The system has a first drive mode and a second drive mode in which the upper limit value of the acceleration of the robot arm is lower than that of the first drive mode, and the robot arm is driven in the second drive mode. Condition B: The distance between the center of gravity of the end effector and the tip of the robot arm is equal to or greater than a predetermined value. Condition C: The end point of the robot arm's motion is unknown. Condition D: When the robot arm has an arm and a shaft that moves up and down in a direction vertical to the arm, the amount by which the shaft protrudes from the arm in the vertical direction is equal to or less than a predetermined value. Condition E: The sum of the weight of the end effector and the weight of the workpiece held by the end effector is less than or equal to a predetermined value. [Brief description of the drawings]

[0009] [Figure 1] 1 is an overall configuration diagram of a robot system according to a first embodiment. [Diagram 2] FIG. 2 is a block diagram showing a configuration of a drive unit. [Diagram 3] FIG. 2 is a block diagram showing a drive control system of the control device. [Figure 4] FIG. 4 is a diagram for explaining the use conditions of the band rejection filter. [Diagram 5] FIG. 4 is a diagram for explaining the use conditions of the band rejection filter. [Figure 6] 13 is a flowchart showing a method for controlling a SCARA robot. [Figure 7] 10 is a flowchart showing a control method for a SCARA robot according to a second embodiment. [Figure 8] FIG. 2 is a block diagram showing a hardware configuration of the robot system. [Figure 9] FIG. 2 is a block diagram showing a hardware configuration of the robot system. [Figure 10] FIG. 2 is a block diagram showing a hardware configuration of the robot system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A robot system, a control device, and a control method of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings.

[0011] Fig. 1 is an overall configuration diagram of a robot system according to a first embodiment. Fig. 2 is a block diagram showing the configuration of a drive unit. Fig. 3 is a block diagram showing a drive control system of a control device. Figs. 4 and 5 are diagrams for explaining the use conditions of a band rejection filter. Fig. 6 is a flowchart showing a method for controlling a SCARA robot.

[0012] The robot system 1 shown in FIG. 1 includes a SCARA robot 2 and a control device 3 that controls the SCARA robot 2.

[0013] <Scara Robot 2> The SCARA robot 2 is also called a horizontal articulated robot, and is used for various tasks such as holding, transporting, assembling, and inspecting workpieces such as electronic components, etc. However, the uses of the SCARA robot 2 are not particularly limited.

[0014] The SCARA robot 2 has a base 21 fixed to the floor, a robot arm 22 connected to the base 21, and piping 29 connecting the base 21 and the robot arm 22. The robot arm 22 has a first arm 23 having a base end connected to the base 21 and rotatable around a first rotation axis J1 relative to the base 21, a second arm 24 having a base end connected to a tip end of the first arm 23 and rotatable around a second rotation axis J2 parallel to the first rotation axis J1 relative to the first arm 23, and a work head 25 disposed at the tip end of the second arm 24.

[0015] The working head 25 has a spline nut 251 and a ball screw nut 252 that are coaxially arranged side by side in the Z-axis direction at the tip of the second arm 24, and a spline shaft 253 that is inserted through the spline nut 251 and the ball screw nut 252. The spline shaft 253 is rotatable about a third rotation axis J3, which is the central axis of the second arm 24, and is movable up and down in the direction along the third rotation axis J3.

[0016] In this embodiment, the first rotation axis J1, the second rotation axis J2, and the third rotation axis J3 are parallel to each other and aligned along the vertical direction. However, the first rotation axis J1, the second rotation axis J2, and the third rotation axis J3 may be aligned along a direction inclined with respect to the vertical direction. Also, at least one of the first rotation axis J1, the second rotation axis J2, and the third rotation axis J3 may be inclined with respect to the other axes. Also, the configuration of the robot arm 22 is not particularly limited, and for example, at least one arm may be further connected between the first arm 23 and the second arm 24.

[0017] A payload 254 for mounting an end effector 4 is provided at the lower end of the spline shaft 253. The end effector 4 mounted on the payload 254 is not particularly limited, and examples thereof include a hand for holding a workpiece W and a tool for processing the workpiece W. The end effector 4 in this embodiment is a hand 40 that clamps and holds the workpiece W between a pair of claws.

[0018] The SCARA robot 2 also has a driving unit 26 that drives the robot arm 22. The driving unit 26 has a driving device 261 that rotates the first arm 23 about the first rotation axis J1 relative to the base 21, a driving device 262 that rotates the second arm 24 about the second rotation axis J2 relative to the first arm 23, a driving device 263 that rotates the spline nut 251 to rotate the spline shaft 253 about the third rotation axis J3, and a driving device 264 that rotates the ball screw nut 252 to raise and lower the spline shaft 253 in a direction along the third rotation axis J3.

[0019] Of these, the driving device 261 is disposed inside the base 21, and the remaining driving devices 262, 263, and 264 are each disposed inside the second arm 24. Also, as shown in Fig. 2, each of these driving devices 261, 262, 263, and 264 has a servo motor 26A as a driving source and an encoder 26B that detects the amount of rotation of the servo motor 26A.

[0020] <Control device 3> The control device 3 drives and controls each part of the SCARA robot 2, in particular the drive unit 26. The control device 3 is composed of, for example, a computer, and has a processor (CPU) that processes information, a memory communicatively connected to the processor, and an external interface. In addition, various programs executable by the processor are stored in the memory, and the processor can read and execute the various programs stored in the memory.

[0021] 3, the control device 3 has a drive control system 31 that drives and controls each servo motor 26A of the drive unit 26. The drive control system 31 has a band rejection filter 311, a selector 312 that changes the setting of the band rejection filter 311, a position control unit 313, a speed control unit 314, and a current control unit 315. For ease of explanation, the following will be described as a representative example in which an operation command Sd of a PTP (Point to Point) control method such as "move from a start point Ps to an end point Pe" is input from the host computer HC.

[0022] A position command P0 is input to the band rejection filter 311 as a control signal based on an operation command Sd from the host computer HC. The position command P0 is generated at every control cycle interval. The band rejection filter 311 is a filter circuit that removes a specific frequency component Hf from the position command P0. The term "removal" includes attenuation to a very low level in addition to complete removal. A band pass filter may be used instead of the band rejection filter 311. In this case, the filter may be set to pass frequency components other than the frequency component Hf. In this application, the band rejection filter 311 will be described as a representative example, but this also includes the case where a band pass filter is used.

[0023] The selector 312 controls ON / OFF of the band elimination filter 311. The selector 312 can also change the frequency component Hf when the band elimination filter 311 is ON. When the band elimination filter 311 is ON, the band elimination filter 311 generates and outputs a corrected position command P1 as a corrected control signal obtained by removing the frequency component Hf from the position command P0. On the other hand, when the band elimination filter 311 is OFF, the band elimination filter 311 outputs the position command P0 as is without removing the frequency component Hf from the position command P0.

[0024] Position control unit 313 performs position loop control based on position command P0 or corrected position command P1 from band rejection filter 311 and position feedback signal Fp from encoder 26B, and outputs speed command V0. Speed ​​control unit 314 performs speed loop control based on speed command V0 from position control unit 313 and speed feedback signal Fv from encoder 26B, and outputs acceleration command A0. Current control unit 315 outputs current command E0 based on acceleration command A0 from speed control unit 314. Then, current command E0 from current control unit 315 is supplied to servo motor 26A, and drive control of servo motor 26A is performed.

[0025] The frequency component Hf removed by the band rejection filter 311 includes the natural frequency f0 of the SCARA robot 2. More specifically, the natural frequency f0 at the posture at the end point Pe indicated by the motion command Sd is included. Therefore, by removing the frequency component Hf from the position command P0 using the band rejection filter 311, it is possible to suppress resonance of the SCARA robot 2 and reduce residual vibration. Note that the residual vibration refers to vibration that continues even after the robot arm 22 reaches the end point Pe and stops.

[0026] Here, the natural frequency f0 of the SCARA robot 2 is given by the following formula (1). In formula (1), k is the spring constant, and M is the load. The spring constant k changes depending on the posture of the robot arm 22. In other words, when the posture of the robot arm 22 at the end point Pe is different, the natural frequency f0 differs for each motion command Sd. Also, the load M is determined mainly by the weights of the robot arm 22, the hand 40, and the workpiece W. Normally, the weights of the robot arm 22 and the hand 40 do not change during work, so it can also be said that the load M changes depending on the weight of the workpiece W. Therefore, each time a new operation command Sd is received, the control device 3 calculates the natural frequency f0 from the posture of the robot arm 22 at the end point Pe included in the operation command Sd (the rotation angle of the first arm 23 around the first rotation axis J1, the rotation angle of the second arm 24 around the second rotation axis J2, the rotation angle of the hand 40 around the third rotation axis J3, and the position of the hand 40 in the direction of the third rotation axis J3) and the weight of the workpiece W held by the hand 40, and sets the frequency component Hf based on the calculated natural frequency f0.

[0027]

number

[0028] Next, the ON / OFF control of the band elimination filter 311 by the selector 312 will be described. In the first case where the operation based on the operation command Sd satisfies at least one of the following conditions A to F, the selector 312 turns the band elimination filter 311 OFF. That is, the control device 3 drives and controls the drive unit 26 using the position command P0. Conversely, in the second case where none of the conditions A to F are satisfied, the band elimination filter 311 is turned ON. That is, the control device 3 drives and controls the drive unit 26 using the corrected position command P1. In this way, by turning the band elimination filter 311 ON only when the operation command Sd satisfies certain conditions, it is possible to improve the working efficiency compared to the case where the band elimination filter 311 is turned ON for all operation commands.

[0029] Work efficiency can be expressed as the time required for one operation, i.e., "takt time," and this takt time is determined by the total time T3 of the operation time T1 for the robot arm 22 to move from the start point Ps to the end point Pe, and the vibration convergence time T2 from when the robot arm 22 stops at the end point Pe until the residual vibration converges to a certain amplitude or less. When the band-elimination filter 311 is ON, the resonance of the SCARA robot 2 is suppressed, so the residual vibration is reduced, and the vibration convergence time T2 is shorter compared to when the band-elimination filter 311 is OFF. On the other hand, the acceleration of the robot arm 22 is reduced because the frequency component Hf is removed from the position command P0, and the operation time T1 is longer compared to when the band-elimination filter 311 is OFF.

[0030] In other words, when the decrease in vibration settling time T2 exceeds the increase in operating time T1, the takt time (total time T3) can be shortened by turning on the band-stop filter 311, but when the decrease in vibration settling time T2 and the increase in operating time T1 are approximately the same, turning on the band-stop filter 311 does not shorten the takt time (total time T3), and when the decrease in vibration settling time T2 is less than the increase in operating time T1, turning on the band-stop filter 311 actually increases the takt time (total time T3). Also, when the SCARA robot 2 performs an operation that is incompatible with the use of the band-stop filter 311, turning off the band-stop filter 311 improves work efficiency.

[0031] Therefore, in the robot system 1, when the effect of shortening the takt time is not expected even if the band elimination filter 311 is turned on, or when an operation is incompatible with the band elimination filter 311, the band elimination filter 311 is controlled to be turned off. Conditions A to F will be described below in order.

[0032] Condition A: The robot system 1 has a first drive mode and a second drive mode in which the upper limit value of the acceleration of the robot arm 22 is lower than that in the first drive mode, and the drive mode related to the operation command Sd is the second drive mode.

[0033] The second drive mode is used, for example, during a test to check the movement of the robot arm 22. By performing a test in the second drive mode, the movement of the robot arm 22 becomes gentle, so that the movement of the robot arm 22 can be checked safely and in detail. In such a second drive mode, the movement of the robot arm 22 is gentle, so that the residual vibration at the time of stopping is small and the vibration convergence time T2 is short. Therefore, if the band rejection filter 311 is turned ON in such a case, the increase in the operation time T1 exceeds the decrease in the vibration convergence time T2, and the takt time is likely to increase instead. Therefore, when the drive mode related to the operation command Sd is the second drive mode, the selector 312 turns the band rejection filter 311 OFF. This suppresses an increase in the takt time, and improves the work efficiency of the robot system 1.

[0034] Condition B: As shown in Fig. 4, the distance D between the center of gravity Gh of the hand 40 and the tip 22t of the robot arm 22 is equal to or greater than a predetermined value SH1. In other words, D≧SH1. The tip 22t of the robot arm 22 refers to the tip of the second arm 24.

[0035] If the separation distance D is large, the calculation accuracy of the natural frequency f0 decreases, and the calculated natural frequency f0 may greatly differ from the actual natural frequency f0. In such a case, if the band-stop filter 311 is turned ON, an appropriate frequency component Hf including the actual natural frequency f0 may not be set, and the resonance of the SCARA robot 2 may not be suppressed. In such a case, it is highly likely that the vibration convergence time T2 cannot be shortened, and only the operation time T1 will simply increase. Therefore, when D≧SH1, the selector 312 turns the band-stop filter 311 OFF. This suppresses an increase in the takt time, and improves the work efficiency of the robot system 1. The predetermined value SH1 can be appropriately set according to the configuration of the SCARA robot 2, and can be determined, for example, by experiments, simulations, etc.

[0036] Condition C: The end point Pe of the robot arm 22 is unknown.

[0037] The fact that the end point Pe of the robot arm 22 is unknown means that the posture of the robot arm 22 at the end point Pe is unknown. Therefore, the spring constant k of the SCARA robot 2 at the end point Pe is unknown, and the calculation accuracy of the natural frequency f0 decreases. If the calculation accuracy of the natural frequency f0 decreases, the calculated natural frequency f0 may greatly deviate from the actual natural frequency f0. In such a case, if the band-elimination filter 311 is turned ON, an appropriate frequency component Hf including the actual natural frequency f0 may not be set, and the resonance of the SCARA robot 2 may not be suppressed. In such a case, it is highly likely that the vibration convergence time T2 cannot be shortened, and only the operation time T1 will simply increase. Therefore, when the end point Pe of the robot arm 22 is unknown, the band-elimination filter 311 is turned OFF. This suppresses an increase in the takt time, and improves the work efficiency of the robot system 1.

[0038] Condition D: As shown in Fig. 4, in the case where the robot arm 22 has the second arm 24 as an arm and the spline shaft 253 as a shaft that moves up and down in the vertical direction relative to the second arm 24, the vertical protrusion amount L of the spline shaft 253 from the second arm 24 is equal to or less than a predetermined value SH2. In other words, L≦SH2.

[0039] When the protrusion amount L is large, the distance between the fulcrum of the spline shaft 253 and the hand 40 becomes long, so the rigidity decreases and the residual vibration when stopped tends to become large. Conversely, when the protrusion amount L is small, the distance between the fulcrum of the spline shaft 253 and the hand 40 becomes short, so the rigidity increases and the residual vibration when stopped tends to become small. Therefore, when L≦SH2, if the band-stop filter 311 is turned ON, the increase in the operation time T1 exceeds the decrease in the vibration convergence time T2, and there is a high possibility that the tact time will increase. Therefore, when L≦SH2, the band-stop filter 311 is turned OFF. This suppresses the increase in the tact time, and improves the work efficiency of the robot system 1. It is preferable to set the predetermined value SH2 to a value at which the increase in the operation time T1 and the decrease in the vibration convergence time T2 are approximately equal.

[0040] Condition E: The load weight M3, which is the sum of the weight M1 of the hand 40 and the weight M2 of the workpiece W held by the hand 40, is equal to or less than a predetermined value SH3. In other words, M3≦SH3.

[0041] When the load weight M3 is large, the inertia generated in the hand 40 when the robot arm 22 is driven is large, so the residual vibration when stopped is large. Conversely, when the load weight M3 is small, the inertia generated in the hand 40 when the robot arm 22 is driven is small, so the residual vibration when stopped is small. Therefore, when M3≦SH3, if the band-stop filter 311 is turned ON, the increase in the operation time T1 exceeds the decrease in the vibration convergence time T2, and there is a high possibility that the takt time will increase. Therefore, when M3≦SH3, the band-stop filter 311 is turned OFF. This suppresses the increase in the takt time, and improves the work efficiency of the robot system 1. It is preferable to set the predetermined value SH3 to a value at which the increase in the operation time T1 and the decrease in the vibration convergence time T2 are approximately equal.

[0042] Condition F: As shown in Fig. 5, the operation command of the robot arm 22 is corrected based on the output of the sensor 6 mounted on the SCARA robot 2. In other words, the drive of the robot arm 22 is controlled based on the output of the sensor 6 mounted on the SCARA robot 2.

[0043] When the band-elimination filter 311 is turned ON, the frequency component Hf is removed from the position command P0, thereby decreasing the acceleration, and the movement trajectory of the robot arm 22 is shifted accordingly. Therefore, it becomes difficult to precisely control the position of the robot arm 22 based on the output of the sensor 6. Therefore, the position control that feeds back the output of the sensor 6 is not compatible with the use of the band-elimination filter 311, and in such a case, the selector 312 turns off the band-elimination filter 311. The sensor 6 is not particularly limited, but examples thereof include a force sensor 61 that detects the force applied to the workpiece W, an acceleration sensor 62 that detects the acceleration of the robot arm 22, and an angular velocity sensor 63 that detects the angular velocity of the robot arm 22. In FIG. 5, a circuit that feeds back the detection signal of the angular velocity sensor 63 is illustrated as an example.

[0044] Conditions A to F have been described above. Next, a method for controlling the SCARA robot 2 by the control device 3 will be described. As shown in FIG. 6, the control method includes a control method determination step S11 for determining whether the received motion command Sd is a PTP control method, and a determination step S12 for determining whether the first case satisfies at least one of conditions A to F, or a second case satisfies none of them. The second case further includes a frequency component determination step S13 for determining a frequency component Hf to be removed from the position command P0 using the band rejection filter 311, a corrected control signal generation step S14 for removing the frequency component Hf from the position command P0 using the band rejection filter 311 to generate a corrected position command P1, and a first control step S15 for controlling the driving unit 26 by the corrected position command P1. The first case further includes a second control step S16 for controlling the driving unit 26 by the position command P0 without performing the frequency component determination step S13 and the corrected control signal generation step S14.

[0045] <<Control method determination step S11>> In this step, first, in step S111, the control device 3 judges whether the motion command Sd is the PTP control method. If the motion command Sd is the PTP control method, in step S112, the control device 3 executes the motion command Sd. The use of the band rejection filter 311 reduces the acceleration of the robot arm 22, which causes the movement trajectory to deviate. Therefore, control methods other than the PTP control method, such as the CP control method that controls the movement path, are not compatible with the control method of this embodiment. Therefore, here, the control method of this embodiment is executed only in the case of the PTP control method.

[0046] <Decision Step S12> In this step, the control device 3 determines whether the operation command Sd is in the first case where at least one of the conditions A to F is satisfied, or in the second case where none of the conditions A to F is satisfied.

[0047] <Frequency component determination step S13> This step is executed when the second case is determined in the determination step S12. In this step, first, in step S131, the control device 3 calculates the natural frequency f0 in the posture of the SCARA robot 2 at the end point Pe based on the posture of the robot arm 22 at the end point Pe, the load weight M3, etc. Next, in step S132, the control device 3 determines the frequency component Hf to be removed using the band rejection filter 311 so as to include the calculated natural frequency f0.

[0048] <Correction control signal generating step S14> In this step, the control device 3 turns on the band rejection filter 311 and generates a corrected position command P1 by removing the frequency component Hf from the position command P0.

[0049] <First control step S15> In this step, the control device 3 controls the driving unit 26 based on the corrected position command P1. That is, the control device 3 supplies the current command E0 generated based on the corrected position command P1 to the driving unit 26 to drive and control the servo motor 26A.

[0050] <<Second control step S16>> In this step, the control device 3 turns off the band rejection filter 311, outputs the position command P0 from the band rejection filter 311 as is, and controls the driving unit 26 based on the position command P0. That is, the control device 3 supplies a current command E0 generated based on the position command P0 to the driving unit 26 to drive and control the servo motor 26A.

[0051] As described above, by controlling the ON / OFF of the band rejection filter 311 and using the band rejection filter 311 only when the operation command indicates that using the band rejection filter 311 would improve work efficiency, the work efficiency of the robot system 1 can be improved.

[0052] The robot system 1 has been described above. As described above, the robot system 1 includes the SCARA robot 2 including the robot arm 22 to which the end effector 4 is attached and the driving unit 26 to drive the robot arm 22, and the control device 3 to control the driving unit 26 based on the position command P0 as a control signal. The control device 3 determines whether the first case is a case in which at least one of the conditions A to E is satisfied, or a case in which none of the conditions are satisfied, and in the first case, the control device 3 controls the driving unit 26 based on the position command P0, and in the second case, the control device 3 determines the frequency component Hf to be removed from the position command P0 using the band rejection filter 311, removes the frequency component Hf from the position command P0 using the band rejection filter 311 to generate a corrected position command P1 as a corrected control signal, and controls the driving unit 26 based on the generated corrected position command P1. According to this configuration, the band rejection filter 311 is used only in the case of a motion command for which the use of the band rejection filter 311 improves the work efficiency, so that an increase in task time can be suppressed and the work efficiency of the robot system 1 can be improved.

[0053] As described above, the condition F is further included, and the first case is when at least one of the conditions A to F is satisfied, and the second case is when none of the conditions are satisfied. This makes it possible to more reliably suppress an increase in task time, and improve the work efficiency of the robot system 1.

[0054] As described above, before determining the frequency component Hf, the control device 3 judges whether the case is the first case or the second case, which makes it easier to control the drive unit .

[0055] As described above, the control device 3 controls the SCARA robot 2, which includes the robot arm 22 to which the end effector 4 is attached and the driving unit 26 that drives the robot arm 22, based on the position command P0 as a control signal. The control device 3 determines whether the first case is a case in which at least one of the conditions A to E is satisfied, or a case in which none of the conditions are satisfied, and controls the driving unit 26 based on the position command P0 in the first case, and determines the frequency component Hf to be removed from the position command P0 using the band rejection filter 311 in the second case, removes the frequency component Hf from the position command P0 using the band rejection filter 311 to generate a corrected position command P1 as a corrected control signal, and controls the driving unit 26 based on the generated corrected position command P1. With this configuration, the band rejection filter 311 is used only in the case of a motion command for which the use of the band rejection filter 311 would improve the work efficiency, so that an increase in task time can be suppressed and the work efficiency of the robot system 1 can be improved.

[0056] As described above, the control method of the SCARA robot 2 by the control device 3 is a method of controlling the SCARA robot 2, which includes the robot arm 22 to which the end effector 4 is attached and the driving unit 26 that drives the robot arm 22, based on the position command P0 as a control signal. This control method has a determination step S12 for determining whether the first case satisfies at least one of the conditions A to E or the second case satisfies none of the conditions. If the second case is present, the control method further includes a frequency component determination step S13 for determining a frequency component Hf to be removed from the position command P0 using the band rejection filter 311, a corrected control signal generation step S14 for removing the frequency component Hf from the position command P0 using the band rejection filter 311 to generate a corrected position command P1 as a corrected control signal, and a first control step S15 for controlling the driving unit 26 by the corrected position command P1. According to this control method, the band rejection filter 311 is used only in the case of a motion command for which the use of the band rejection filter 311 improves the work efficiency, so that an increase in task time can be suppressed and the work efficiency of the robot system 1 can be improved.

[0057] As described above, the control method includes, in the first case, a second control step S16 of controlling the drive unit 26 by the position command P0, which makes the control in the first case easier.

[0058] As described above, the condition F is further included, and the first case is when at least one of the conditions A to F is satisfied, and the second case is when none of the conditions are satisfied. This makes it possible to more reliably suppress an increase in task time, and improve the work efficiency of the robot system 1.

[0059] <Second embodiment> FIG. 7 is a flowchart showing a control method for a SCARA robot according to the second embodiment.

[0060] The robot system 1 of this embodiment is similar to the robot system 1 of the first embodiment described above, except that the control method of the SCARA robot 2 by the control device 3 is different. In the following description, the present embodiment will be described focusing on the differences from the previous embodiment, and the description of the similarities will be omitted. In FIG. 7, the same reference numerals are used for the same configurations as the previous embodiment.

[0061] As shown in FIG. 7, the control method for the SCARA robot 2 in this embodiment includes a control method determination step S21 for determining whether the received operation command Sd is a PTP control method, a frequency component determination step S22 for determining a frequency component Hf to be removed from the position command P0 using the band rejection filter 311, a corrected control signal generation step S23 for removing the frequency component Hf from the position command P0 using the band rejection filter 311 to generate a corrected position command P1, and a control step S24 for controlling the drive unit 26 using the position command P0 in a first case in which at least one of conditions A to F is satisfied, and controlling the drive unit 26 using the corrected position command P1 in a second case in which all of the conditions A to F are not satisfied.

[0062] <<Control method determination step S21>> In this step, first, in step S211, the control device 3 determines whether the operation command Sd is in the PTP control method. If the operation command Sd is in the PTP control method, in step S212, the control device 3 executes the operation command Sd.

[0063] <Frequency component determination step S22> In this step, first, in step S221, the control device 3 calculates the natural frequency f0 in the posture of the SCARA robot 2 at the end point Pe based on the posture of the robot arm 22 at the end point Pe, the load weight M3, etc. Next, in step S222, the control device 3 determines the frequency component Hf so as to include the calculated natural frequency f0.

[0064] <<Correction control signal generating step S23>> In this step, the control device 3 turns on the band rejection filter 311, removes the frequency component Hf from the position command P0, thereby generating a corrected position command P1, and outputs the generated corrected position command P1.

[0065] <<Control step S24>> In this step, in step S241, the control device 3 determines whether it is a first case in which at least one of the conditions A to F is satisfied, or a second case in which none of the conditions A to F are satisfied. In the first case, in step S242, the control device 3 turns off the band rejection filter 311 and drives and controls the drive unit 26 using the position command P0 without using the corrected position command P1 generated in the corrected control signal generating step S23. On the other hand, in the second case, in step S243, the control device 3 drives and controls the drive unit 26 using the corrected position command P1 generated in the corrected control signal generating step S23.

[0066] In this way, the control device 3 of this embodiment generates the corrected position command P1, and then judges whether the case is the first case or the second case. This method also makes it easier to control the SCARA robot 2.

[0067] As described above, by controlling the ON / OFF of the band rejection filter 311 and using the band rejection filter 311 only when the operation command indicates that using the band rejection filter 311 would improve work efficiency, the work efficiency of the robot system 1 can be improved.

[0068] As described above, in the robot system 1 of this embodiment, after generating the corrected position command P1, the control device 3 judges whether the case is the first case or the second case. This method also makes it easier to control the SCARA robot 2.

[0069] As described above, the control method of the SCARA robot 2 by the control device 3 is a method of controlling the SCARA robot 2, which includes the robot arm 22 to which the end effector 4 is attached and the driving unit 26 that drives the robot arm 22, based on the position command P0 as a control signal. This control method includes a frequency component determination step S22 of determining a frequency component Hf to be removed from the position command P0 using the band rejection filter 311, a corrected control signal generation step S23 of removing the frequency component Hf from the position command P0 using the band rejection filter 311 to generate a corrected position command P1 as a corrected control signal, and a control step S24 of controlling the driving unit 26 by the position command P0 in a first case where at least one of the conditions A to E is satisfied, and controlling the driving unit 26 by the corrected position command P1 in a second case where all of the conditions A to E are not satisfied. According to this control method, the band rejection filter 311 is used only in the case of a motion command where the use of the band rejection filter 311 improves the work efficiency, so that an increase in task time can be suppressed and the work efficiency of the robot system 1 can be improved.

[0070] Although the robot system, the control device, and the control method of the present invention have been described above with reference to the illustrated embodiments, the present invention is not limited to these. Furthermore, each part constituting the robot system can be replaced with any other part capable of performing the same function. Furthermore, any other component can be added.

[0071] The hardware configuration of the robot system is explained below. Fig. 8 shows the overall configuration of a robot system 1A in which a SCARA robot 2, a controller 51, and a computer 52 are connected. The SCARA robot 2 may be controlled by a processor in the controller 51 reading out instructions from a memory and executing the instructions, or a processor in the computer 52 reading out instructions from a memory and executing the instructions via the controller 51. Therefore, either or both of the controller 51 and the computer 52 can be regarded as the "control device 3."

[0072] 9 shows the overall configuration of a robot system 1B in which a computer 53 is directly connected to the SCARA robot 2. The SCARA robot 2 is controlled directly by a processor in the computer 53 reading out commands from a memory. Therefore, the computer 53 can be considered as the "control device 3."

[0073] 10 shows the overall configuration of a robot system 1C in which a SCARA robot 2 incorporating a controller 54 is connected to a computer 55, and the computer 55 is connected to a cloud 57 via a network 56 such as a LAN. The SCARA robot 2 may be controlled by a processor present in the computer 55 reading out instructions from a memory, or may be controlled by a processor present on the cloud 57 reading out instructions from a memory via the computer 55. Therefore, any one, any two, or any three of the controller 54, the computer 55, and the cloud 57 can be regarded as the "control device 3." [Explanation of symbols]

[0074] 1...robot system, 1A...robot system, 1B...robot system, 1C...robot system, 2...SCARA robot, 21...base, 22...robot arm, 22t...tip, 23...first arm, 24...second arm, 25...work head, 251...spline nut, 252...ball screw nut, 253...spline shaft, 254...payload, 26...drive unit, 26A...servo motor, 26B...encoder, 261...drive device, 262...drive device, 263...drive Apparatus, 264...Drive device, 29...Pipe, 3...Control device, 31...Drive control system, 311...Band rejection filter, 312...Selector, 313...Position control unit, 314...Speed ​​control unit, 315...Current control unit, 4...End effector, 40...Hand, 51...Controller, 52...Computer, 53...Computer, 54...Controller, 55...Computer, 56...Network, 57...Cloud, 6...Sensor, 61...Force sensor, 62...Acceleration sensor, 63...Angular velocity degree sensor, A0...acceleration command, D...separation distance, E0...current command, Fp...position feedback signal, Fv...velocity feedback signal, Gh...centre of gravity, HC...host computer, J1...first rotary axis, J2...second rotary axis, J3...third rotary axis, M1...weight, M2...weight, M3...load weight, L...projection amount, P0...position command, P1...corrected position command, S11...control method determination step, S111...step, S112...step, S12...determination step, S13...frequency component determination step, S131... step, S132... step, S14... compensation control signal generating step, S15... first control step, S16... second control step, S21... control method determining step, S211... step, S212... step, S22... frequency component determining step, S221... step, S222... step, S23... compensation control signal generating step, S24... control step, S241... step, S242... step, S243... step, Sd... motion command, V0... speed command, W... workpiece

Claims

1. a SCARA robot including a robot arm to which an end effector is attached and a drive unit that drives the robot arm; A control device that controls the drive unit based on a control signal, The control device includes: Determine whether the present invention is in a first case in which at least one of the following conditions A to E is satisfied, or in a second case in which none of the following conditions is satisfied: In the first case, the drive unit is controlled based on the control signal; In the second case, a frequency component to be removed from the control signal is determined using a band-stop filter, the frequency component is removed from the control signal using the band-stop filter to generate a corrected control signal, and the robot system controls the drive unit based on the generated corrected control signal. Condition A: The system has a first drive mode and a second drive mode in which the upper limit value of the acceleration of the robot arm is lower than that of the first drive mode, and the robot arm is driven in the second drive mode. Condition B: The distance between the center of gravity of the end effector and the tip of the robot arm is equal to or greater than a predetermined value. Condition C: The end point of the robot arm's motion is unknown. Condition D: When the robot arm has an arm and a shaft that moves up and down in a direction vertical to the arm, the amount by which the shaft protrudes from the arm in the vertical direction is less than a predetermined value. Condition E: The sum of the weight of the end effector and the weight of the workpiece held by the end effector is less than or equal to a predetermined value.

2. Furthermore, the following condition F is satisfied: The robot system according to claim 1 , wherein a case where at least one of the conditions A to F is satisfied is defined as the first case, and a case where all of the conditions A to F are not satisfied is defined as the second case. Condition F: The drive of the robot arm is controlled based on the output of a sensor mounted on the SCARA robot.

3. The robot system according to claim 1 or 2, wherein the control device determines whether the first case or the second case exists before determining the frequency component.

4. 3. The robot system according to claim 1, wherein the control device determines whether the first case or the second case occurs after generating the corrected control signal.

5. A control device that controls a SCARA robot based on a control signal, the SCARA robot including a robot arm to which an end effector is attached and a drive unit that drives the robot arm, Determine whether the present invention is in a first case in which at least one of the following conditions A to E is satisfied, or in a second case in which none of the following conditions is satisfied: In the first case, the drive unit is controlled based on the control signal; In the second case, a control device is characterized in that it determines a frequency component to be removed from the control signal using a band-elimination filter, removes the frequency component from the control signal using the band-elimination filter to generate a corrected control signal, and controls the drive unit based on the generated corrected control signal. Condition A: The system has a first drive mode and a second drive mode in which the upper limit value of the acceleration of the robot arm is lower than that of the first drive mode, and the robot arm is driven in the second drive mode. Condition B: The distance between the center of gravity of the end effector and the tip of the robot arm is equal to or greater than a predetermined value. Condition C: The end point of the robot arm's motion is unknown. Condition D: When the robot arm has an arm and a shaft that moves up and down in a direction vertical to the arm, the amount by which the shaft protrudes from the arm in the vertical direction is less than a predetermined value. Condition E: The sum of the weight of the end effector and the weight of the workpiece held by the end effector is less than or equal to a predetermined value.

6. 1. A control method for controlling a SCARA robot including a robot arm to which an end effector is attached and a drive unit that drives the robot arm, based on a control signal, comprising: a frequency component determining step of determining a frequency component to be removed from the control signal using a band rejection filter; a corrected control signal generating step of removing the frequency component from the control signal using the band rejection filter to generate a corrected control signal; a control step of controlling the drive unit by the control signal in a first case where at least one of the following conditions A to E is satisfied, and controlling the drive unit by the corrected control signal in a second case where all of the following conditions A to E are not satisfied. Condition A: The system has a first drive mode and a second drive mode in which the upper limit value of the acceleration of the robot arm is lower than that of the first drive mode, and the robot arm is driven in the second drive mode. Condition B: The distance between the center of gravity of the end effector and the tip of the robot arm is equal to or greater than a predetermined value. Condition C: The end point of the robot arm's motion is unknown. Condition D: When the robot arm has an arm and a shaft that moves up and down in a direction vertical to the arm, the amount by which the shaft protrudes from the arm in the vertical direction is less than a predetermined value. Condition E: The sum of the weight of the end effector and the weight of the workpiece held by the end effector is less than or equal to a predetermined value.

7. 1. A control method for controlling a SCARA robot including a robot arm to which an end effector is attached and a drive unit that drives the robot arm, based on a control signal, comprising: A determination step of determining whether the present invention is a first case in which at least one of the following conditions A to E is satisfied, or a second case in which none of the following conditions is satisfied, In the second case, further a frequency component determining step of determining a frequency component to be removed from the control signal using a band rejection filter; a corrected control signal generating step of removing the frequency component from the control signal using the band rejection filter to generate a corrected control signal; A first control step of controlling the driving unit by the corrected control signal is executed; A control method comprising the steps of: in the first case, further executing a second control step of controlling the drive unit using the control signal. Condition A: The system has a first drive mode and a second drive mode in which the upper limit value of the acceleration of the robot arm is lower than that of the first drive mode, and the robot arm is driven in the second drive mode. Condition B: The distance between the center of gravity of the end effector and the tip of the robot arm is equal to or greater than a predetermined value. Condition C: The end point of the robot arm's motion is unknown. Condition D: When the robot arm has an arm and a shaft that moves up and down in a direction vertical to the arm, the amount by which the shaft protrudes from the arm in the vertical direction is less than a predetermined value. Condition E: The sum of the weight of the end effector and the weight of the workpiece held by the end effector is less than or equal to a predetermined value.

8. Furthermore, the following condition F is satisfied:

8. The control method according to claim 6, wherein a case where at least one of the conditions A to F is satisfied is defined as the first case, and a case where all of the conditions A to F are not satisfied is defined as the second case. Condition F: The drive of the robot arm is controlled based on the output of a sensor mounted on the SCARA robot.

Images