Robot system, control device, and control method

Abstract

A robot system, a control device, and a control method that can achieve high operation efficiency. The robot system includes: a horizontal multi-joint robot having a robotic arm with an end effector attached thereto and a drive unit for driving the robotic arm; and a control device that controls the drive unit based on a control signal. The control device determines whether it is a first case where a specified condition is satisfied or a second case where it is not satisfied. In the first case, it controls the drive unit based on the control signal. In the second case, it determines the frequency components to be removed from the control signal using a band-stop filter, removes the frequency components from the control signal using the band-stop filter and generates a corrected control signal, and controls the drive unit based on the generated corrected control signal.

Description

Technical Field

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

[0002] For example, Patent Document 1 describes the following: For a robot having an arm with an end effector mounted at the front end, if the shape of the end effector is large, when the robot moves, the end effector itself may vibrate and the working efficiency may decrease. Therefore, the natural vibration frequency in the state where the hand holds the workpiece is measured in advance, and a band-stop filter is applied to the torque control signal for moving the arm according to the measured natural vibration frequency.

[0003] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2001-293638

[0004] However, for a specific operation, high working efficiency may be achieved without applying a band-stop filter. Therefore, if a band-stop filter is applied to all operations, the working efficiency may instead decrease. Summary of the Invention

[0005] A robot system, characterized by comprising:

[0006] A horizontally articulated robot, including a robotic arm having an end effector mounted thereon and a drive unit for driving the robotic arm; and

[0007] A control device that controls the drive unit based on a control signal,

[0008] In the control device,

[0009] It is determined whether it is a first case or a second case, where the first case is that at least one of the following conditions A to E is satisfied, and the second case is that all of the conditions A to E are not satisfied,

[0010] In the first case, the drive unit is controlled based on the control signal,

[0011] In the second case, the frequency component to be removed from the control signal using a band-stop filter is determined, 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,

[0012] Condition A: There is a first drive mode and a second drive mode in which the upper limit value of the acceleration of the robotic arm is smaller than that in the first drive mode, and the robotic arm is driven in the second drive mode;

[0013] Condition B: The separation distance between the center of gravity of the end effector and the front end of the robotic arm is equal to or greater than a specified value;

[0014] Condition C: The end point of the movement of the robotic arm is unknown;

[0015] Condition D: When the robotic arm has an arm and an axis that moves up and down in the vertical direction with respect to the arm, the amount of protrusion of the axis from the arm in the vertical direction is equal to or less than a specified value;

[0016] Condition E: The total weight of the end effector and the workpiece held by the end effector is equal to or less than a specified value.

[0017] A control device, characterized in that

[0018] Based on a control signal, it controls a horizontal multi-joint robot, where the horizontal multi-joint robot includes a robotic arm equipped with an end effector and a drive unit that drives the robotic arm,

[0019] In the control device,

[0020] It is determined whether it is the first case or the second case, where the first case is that at least one of the following Conditions A to E is satisfied, and the second case is that all of Conditions A to E are not satisfied,

[0021] In the first case, the drive unit is controlled based on the control signal,

[0022] In the second case, the frequency component to be removed from the control signal using a band-stop filter is determined, 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,

[0023] Condition A: There is a first drive mode and a second drive mode in which the upper limit value of the acceleration of the robotic arm is smaller than that in the first drive mode, and the robotic arm is driven in the second drive mode;

[0024] Condition B: The separation distance between the center of gravity of the end effector and the front end of the robotic arm is equal to or greater than a specified value;

[0025] Condition C: The end point of the movement of the robotic arm is unknown;

[0026] Condition D: When the robotic arm has an arm and an axis that moves up and down in the vertical direction with respect to the arm, the amount of protrusion of the axis from the arm in the vertical direction is equal to or less than a specified value;

[0027] Condition E: The total weight of the end effector and the workpiece held by the end effector is equal to or less than a specified value.

[0028] A control method, characterized in that

[0029] Based on a control signal, a horizontal multi-joint robot is controlled, wherein the horizontal multi-joint robot includes a robotic arm equipped with an end effector and a driving unit for driving the robotic arm.

[0030] The control method includes:

[0031] A frequency component determination step of determining a frequency component removed from the control signal using a band-stop filter;

[0032] A corrected control signal generation step of removing the frequency component from the control signal using the band-stop filter and generating a corrected control signal; and

[0033] A control step of, in a first case, controlling the driving unit according to the control signal, and in a second case, controlling the driving unit according to the corrected control signal, wherein the first case is when at least one of the following conditions A to E is satisfied, and the second case is when none of the conditions A to E are satisfied.

[0034] Condition A: There is a first driving mode and a second driving mode in which the upper limit value of the acceleration of the robotic arm is smaller than that of the first driving mode, and the robotic arm is driven in the second driving mode;

[0035] Condition B: The separation distance between the center of gravity of the end effector and the front end of the robotic arm is equal to or greater than a specified value;

[0036] Condition C: The end point of the movement of the robotic arm is unknown;

[0037] Condition D: In the case where the robotic arm has an arm and an axis that moves up and down in the vertical direction with respect to the arm, the protrusion amount of the axis from the arm in the vertical direction is equal to or less than a specified value;

[0038] Condition E: The sum of the weight of the end effector and the weight of the workpiece held by the end effector is equal to or less than a specified value.

[0039] A control method, characterized in that

[0040] Based on a control signal, a horizontal multi-joint robot is controlled, wherein the horizontal multi-joint robot includes a robotic arm equipped with an end effector and a driving unit for driving the robotic arm.

[0041] There is a determination step of determining whether it is the first case or the second case, wherein the first case is when at least one of the following conditions A to E is satisfied, and the second case is when none of the conditions A to E are satisfied.

[0042] In the second case, it further includes:

[0043] a frequency component determination step of determining the frequency component removed from the control signal using a band-stop filter;

[0044] a corrected control signal generation step of removing the frequency component from the control signal using the band-stop filter and generating a corrected control signal; and

[0045] a first control step of controlling the drive unit according to the corrected control signal,

[0046] Condition A: having a first driving mode and a second driving mode in which the upper limit value of the acceleration of the robotic arm is smaller than that in the first driving mode, and driving the robotic arm in the second driving mode;

[0047] Condition B: the separation distance between the center of gravity of the end effector and the front end of the robotic arm is equal to or greater than a specified value;

[0048] Condition C: the end point of the movement of the robotic arm is unknown;

[0049] Condition D: in the case where the robotic arm has an arm and an axis that moves up and down in the vertical direction with respect to the arm, the protrusion amount of the axis from the arm in the vertical direction is equal to or less than a specified value;

[0050] Condition E: the sum of the weight of the end effector and the weight of the workpiece held by the end effector is equal to or less than a specified value. Description of the Drawings

[0051] Figure 1 is an overall configuration diagram of the robot system according to the first embodiment.

[0052] Figure 2 is a block diagram showing the configuration of the drive unit.

[0053] Figure 3 is a block diagram showing the drive control system included in the control device.

[0054] Figure 4 is a diagram for explaining the usage conditions of the band-stop filter.

[0055] Figure 5 is a diagram for explaining the usage conditions of the band-stop filter.

[0056] Figure 6 is a flowchart showing the control method of the horizontal multi-joint robot.

[0057] Figure 7 is a flowchart showing the control method of the horizontal multi-joint robot according to the second embodiment.

[0058] Figure 8 is a block diagram showing the hardware configuration of the robot system.

[0059] Figure 9 is a block diagram showing the hardware configuration of the robot system.

[0060] Figure 10 is a block diagram showing the hardware configuration of the robot system.

[0061] Symbol Explanation

[0062] 1... robot system; 1A... robot system; 1B... robot system; 1C... robot system; 2... horizontal multi-joint robot; 21... base; 22... robotic arm; 22t... front end; 23... first arm; 24... second arm; 25... end effector; 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 device; 264... drive device; 29... pipe laying; 3... control device; 31... drive control system; 311... band-stop 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 sensor; A0... acceleration command; D... separation distance; E0... current command; Fp... position feedback signal; Fv... speed feedback signal; Gh... center of gravity; HC... host computer; J1... first rotation axis; J2... second rotation axis; J3... third rotation axis; M1... weight; M2... weight; M3... load weight; L... protrusion; P0... position command; P1... corrected position command; S11... control mode determination step; S111... step; S112... step; S12... determination step; S13... frequency component determination step; S131... step; S132... step; S14... corrected control signal generation step; S15... first control step; S16... second control step; S21... control mode determination step; S211... step; S212... step; S22... frequency component determination step; S221... step; S222... step; S23... corrected control signal generation step; S24... control step; S241... step; S242... step; S243... step; Sd... action command; V0... speed command; W... workpiece. Detailed Implementation Manner

[0063] Next, based on the preferred embodiments shown in the accompanying drawings, the robot system, control device, and control method of the present invention will be described in detail.

[0064] Figure 1 is an overall configuration diagram of the robot system according to the first embodiment. Figure 2 is a block diagram showing the configuration of the drive unit. Figure 3 is a block diagram showing the drive control system included in the control device. Figure 4 and Figure 5 are diagrams for explaining the usage conditions of the band-stop filter, respectively. Figure 6 is a flowchart showing the control method of the horizontal articulated robot.

[0065] Figure 1 The robot system 1 shown includes a horizontal articulated robot 2 and a control device 3 that controls the horizontal articulated robot 2.

[0066] Horizontal articulated robot 2

[0067] The horizontal articulated robot 2 is also referred to as a horizontal articulated robot and is used, for example, in various operations such as holding, transporting, assembling, and inspecting workpieces such as electronic components. However, the use of the horizontal articulated robot 2 is not particularly limited.

[0068] The horizontal articulated robot 2 includes: a base 21 fixed to the ground; a robotic arm 22 connected to the base 21; and a pipe duct 29 connecting the base 21 and the robotic arm 22. In addition, the robotic arm 22 includes: a first arm 23 having a base end connected to the base 21 and capable of rotating relative to the base 21 about a first rotation axis J1; a second arm 24 having a base end connected to the front end of the first arm 23 and capable of rotating relative to the first arm 23 about a second rotation axis J2 parallel to the first rotation axis J1; and an end effector 25 disposed at the front end of the second arm 24.

[0069] The end effector 25 includes: a spline nut 251 and a ball screw nut 252 disposed side by side and coaxially in the Z-axis direction at the front end of the second arm 24; and a spline shaft 253 passing through the spline nut 251 and the ball screw nut 252. The spline shaft 253 can rotate relative to the second arm 24 about a third rotation axis J3 serving as its central axis and can move up and down in the direction along the third rotation axis J3.

[0070] In the present embodiment, the first rotation axis J1, the second rotation axis J2, and the third rotation axis J3 are parallel to each other and along the vertical direction. However, the first rotation axis J1, the second rotation axis J2, and the third rotation axis J3 may be along an inclined direction with respect to the vertical direction. In addition, at least one of the first rotation axis J1, the second rotation axis J2, and the third rotation axis J3 may also be inclined with respect to the other axes. Further, the configuration of the robotic arm 22 is not particularly limited. For example, at least one arm may also be connected between the first arm 23 and the second arm 24.

[0071] A payload 254 for mounting the 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. For example, a hand for holding the workpiece W, a working tool for machining the workpiece W, etc. may be cited. The end effector 4 of the present embodiment is a hand 40 that holds and retains the workpiece W by using a pair of claw portions.

[0072] In addition, the horizontal articulated robot 2 has a drive unit 26 that drives the robotic arm 22. The drive unit 26 has: a drive device 261 that rotates the first arm 23 relative to the base 21 about the first rotation axis J1; a drive device 262 that rotates the second arm 24 relative to the first arm 23 about the second rotation axis J2; a drive device 263 that rotates the spline nut 251 to rotate the spline shaft 253 about the third rotation axis J3; and a drive device 264 that rotates the ball screw nut 252 and raises and lowers the spline shaft 253 in the direction along the third rotation axis J3.

[0073] Among them, the drive device 261 is arranged in the base 21, and the remaining drive devices 262, 263, and 264 are respectively arranged in the second arm 24. In addition, as Figure 2 shown, these drive devices 261, 262, 263, and 264 respectively have a servo motor 26A as a drive source and an encoder 26B that detects the rotation amount of the servo motor 26A.

[0074] The control device 3

[0075] The control device 3 performs drive control on each part of the horizontal articulated robot 2, particularly the drive unit 26. The control device 3 is constituted by a computer, for example, and has a processor (CPU) that processes information, a memory communicably connected to the processor, and an external interface. In addition, various programs that can be executed by the processor are stored in the memory, and the processor can read and execute various programs stored in the memory, etc.

[0076] As Figure 3As shown, the control device 3 has a drive control system 31 that drives and controls each servo motor 26A included in the drive unit 26. The drive control system 31 includes a band-stop filter 311, a selector 312 that changes the setting of the band-stop filter 311, a position control unit 313, a speed control unit 314, and a current control unit 315. Hereinafter, for ease of explanation, the case where an operation instruction Sd in a PTP (Point to Point) control mode of "move from the start point Ps to the end point Pe" is input from the host computer HC will be described as a representative example.

[0077] A position command P0, which is a control signal based on the operation instruction Sd from the host computer HC, is input to the band-stop filter 311. In addition, the position command P0 is generated at each control cycle interval. The band-stop filter 311 is a filter circuit that removes a specific frequency component Hf from the position command P0. Here, the "removal" includes not only complete removal but also attenuation to a very low level. Here, a band-pass filter may be used instead of the band-stop filter 311. In this case, any setting that allows frequency components other than the frequency component Hf to pass through may be used. In the present application, the band-stop filter 311 is described as a representative example, but it also includes cases where a band-pass filter is used.

[0078] The selector 312 controls the ON / OFF of the band-stop filter 311. The selector 312 can also change the frequency component Hf when the band-stop filter 311 is ON. When the band-stop filter 311 is ON, the band-stop filter 311 generates and outputs a corrected position command P1, which is a corrected control signal obtained by removing the frequency component Hf from the position command P0. On the other hand, when the band-stop filter 311 is OFF, the band-stop filter 311 directly outputs the position command P0 without removing the frequency component Hf from the position command P0.

[0079] The position control unit 313 performs position loop control based on the position command P0 or the corrected position command P1 from the band-stop filter 311 and the position feedback signal Fp from the encoder 26B, and outputs a speed command V0. The speed control unit 314 performs speed loop control based on the speed command V0 from the position control unit 313 and the speed feedback signal Fv from the encoder 26B, and outputs an acceleration command A0. The current control unit 315 outputs a current command E0 based on the acceleration command A0 from the speed control unit 314. Then, the current command E0 from the current control unit 315 is supplied to the servo motor 26A to perform drive control of the servo motor 26A.

[0080] The frequency component Hf removed by the band-stop filter 311 includes the natural vibration frequency f0 of the horizontal articulated robot 2. More specifically, it includes the natural vibration frequency f0 in the posture at the end point Pe represented by the motion command Sd. Therefore, by removing the frequency component Hf from the position command P0 using the band-stop filter 311, resonance of the horizontal articulated robot 2 can be suppressed, and residual vibration can be suppressed to a small level. In addition, the residual vibration refers to the vibration that continues after the robotic arm 22 reaches the end point Pe and stops.

[0081] Here, the natural vibration frequency f0 of the horizontal articulated robot 2 is represented by the following formula (1). In formula (1), k is the spring constant and M is the load. The spring constant k varies according to the posture of the robotic arm 22. That is, if the posture of the robotic arm 22 at the end point Pe is different, the natural vibration frequency f0 is different in each such motion command Sd. In addition, the load M is mainly determined by the weights of the robotic arm 22, the hand 40, and the workpiece W. Usually, the weights of the robotic arm 22 and the hand 40 do not change during operation, so it can also be considered that the load M varies according to the weight of the workpiece W. Therefore, each time the control device 3 receives a new motion command Sd, it calculates the natural vibration frequency f0 based on the posture of the robotic arm 22 at the end point Pe included in the motion 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 vibration frequency f0.

[0082]

Formula 1

[0083]

[0084] Next, the ON / OFF control of the band-stop filter 311 based on the selector 312 will be described. The selector 312 sets the band-stop filter 311 to OFF in a first case where the motion based on the motion command Sd satisfies at least one of the following conditions A to F. That is, the control device 3 performs drive control of the drive unit 26 using the position command P0. On the contrary, in a second case where none of the conditions A to F are satisfied, the band-stop filter 311 is set to ON. That is, the control device 3 performs drive control of the drive unit 26 using the corrected position command P1. Thus, by setting the band-stop filter 311 to ON only in the case of a motion command Sd that satisfies certain conditions, the operation efficiency can be improved compared to the case where the band-stop filter 311 is set to ON for all motion commands.

[0085] The operation efficiency can be represented by the time taken for one operation, i.e., the "takt time", which is determined by the total time T3 of the operation time T1 for the robotic arm 22 to move from the start point Ps to the end point Pe and the vibration convergence time T2 until the residual vibration converges to below a certain amplitude after stopping at the end point Pe. When the band-stop filter 311 is ON, since the resonance of the horizontal articulated robot 2 is suppressed, the residual vibration becomes smaller, and the vibration convergence time T2 becomes shorter correspondingly compared with the case where the band-stop filter 311 is OFF. On the other hand, since the frequency component Hf is removed from the position command P0, the acceleration of the robotic arm 22 decreases, and the operation time T1 becomes longer correspondingly compared with the case where the band-stop filter 311 is OFF.

[0086] That is, when the decrease in the vibration convergence time T2 exceeds the increase in the operation time T1, turning on the band-stop filter 311 can shorten the takt time (total time T3). However, when the decrease in the vibration convergence time T2 and the increase in the operation time T1 are of the same degree, even if the band-stop filter 311 is turned on, the takt time (total time T3) cannot be shortened. When the decrease in the vibration convergence time T2 is less than the increase in the operation time T1, if the band-stop filter 311 is turned on, the takt time (total time T3) will increase instead. In addition, even when the horizontal articulated robot 2 performs an operation with poor compatibility with the use of the band-stop filter 311, turning off the band-stop filter 311 can improve the operation efficiency.

[0087] Therefore, in the robot system 1, when the shortening effect of the takt time cannot be expected even if the band-stop filter 311 is turned on, and in the case of an operation with poor compatibility with the band-stop filter 311, the ON / OFF of the band-stop filter 311 is controlled to turn the band-stop filter 311 OFF. Hereinafter, conditions A to F will be described in sequence.

[0088] Condition A: When the operation command Sd is in the second drive mode, where the robot system 1 has a first drive mode and a second drive mode with a smaller upper limit value of the acceleration of the robotic arm 22 compared with the first drive mode.

[0089] The second drive mode is used, for example, during a test for confirming the movement of the robotic arm 22. By conducting the test in the second drive mode, the movement of the robotic arm 22 becomes smooth, so that the movement of the robotic arm 22 can be confirmed safely and in detail. In this second drive mode, since the movement of the robotic arm 22 is smooth, the residual vibration at the time of stopping is small and the vibration convergence time T2 is short. Therefore, in this case, if the band-stop filter 311 is set to ON and the increase amount of the operation time T1 exceeds the decrease amount of the vibration convergence time T2, there is a high possibility that the cycle time will increase instead. Therefore, when the drive mode of the operation instruction Sd is the second drive mode, the selector 312 sets the band-stop filter 311 to OFF. Thereby, an increase in the cycle time is suppressed and the operation efficiency of the robot system 1 is improved.

[0090] Condition B: As Figure 4 shown, the separation distance D between the center of gravity Gh of the hand 40 and the tip 22t of the robotic arm 22 is equal to or greater than a specified value SH1. That is, D≥SH1. In addition, the tip 22t of the robotic arm 22 refers to the tip of the second arm 24.

[0091] If the separation distance D is large, the calculation accuracy of the natural vibration frequency f0 decreases, and there is a possibility that the calculated natural vibration frequency f0 deviates significantly from the actual natural vibration frequency f0. In this case, if the band-stop filter 311 is set to ON, an appropriate frequency component Hf including the actual natural vibration frequency f0 cannot be set, and it may not be possible to suppress the resonance of the horizontally articulated robot 2. In this case, it is not possible to shorten the vibration convergence time T2, and there is a high possibility that only the operation time T1 increases. Therefore, when D≥SH1, the selector 312 sets the band-stop filter 311 to OFF. Thereby, an increase in the cycle time is suppressed and the operation efficiency of the robot system 1 is improved. In addition, the specified value SH1 can be appropriately set according to the configuration of the horizontally articulated robot 2, and can be determined, for example, through experiments, simulations, etc.

[0092] Condition C: The end point Pe of the robotic arm 22 is unknown.

[0093] The fact that the end point Pe of the robotic arm 22 is unknown means that the posture of the robotic arm 22 at the end point Pe is unclear. Therefore, the spring constant k of the horizontally articulated robot 2 at the end point Pe is unknown, and the calculation accuracy of the natural vibration frequency f0 is reduced. If the calculation accuracy of the natural vibration frequency f0 is reduced, the calculated natural vibration frequency f0 may deviate significantly from the actual natural vibration frequency f0. In this case, if the band-stop filter 311 is set to ON, an appropriate frequency component Hf including the actual natural vibration frequency f0 cannot be set, and it may not be possible to suppress the resonance of the horizontally articulated robot 2. In this case, it is not possible to shorten the vibration convergence time T2, and there is a high possibility that only the operation time T1 increases. Therefore, when the end point Pe of the robotic arm 22 is unknown, the band-stop filter 311 is set to OFF. Thereby, an increase in the cycle time is suppressed, and the operation efficiency of the robot system 1 is improved.

[0094] Condition D: As Figure 4 shown, when the robotic arm 22 has a second arm 24 as an arm and a spline shaft 253 as a shaft that moves up and down in the vertical direction with respect to the second arm 24, the protrusion amount L of the spline shaft 253 in the vertical direction from the second arm 24 is equal to or less than a specified value SH2. That is, L ≤ SH2.

[0095] If 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 at the time of stopping tends to become large. On the contrary, if 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 becomes high and the residual vibration at the time of stopping tends to become small. Therefore, when L ≤ SH2, if the band-stop filter 311 is set to ON, the increase amount of the operation time T1 exceeds the decrease amount of the vibration convergence time T2, and there is a high possibility that the cycle time increases instead. Therefore, when L ≤ SH2, the band-stop filter 311 is set to OFF. Thereby, an increase in the cycle time is suppressed, and the operation efficiency of the robot system 1 is improved. In addition, the specified value SH2 is preferably set to a value such that the increase amount of the operation time T1 and the decrease amount of the vibration convergence time T2 are substantially equal.

[0096] 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 specified value SH3. That is, M3 ≤ SH3.

[0097] If the load weight M3 is large, the inertia generated at the hand 40 when driving the robotic arm 22 becomes large, and thus the residual vibration at the time of stopping becomes large. On the contrary, if the load weight M3 is small, the inertia generated at the hand 40 when driving the robotic arm 22 becomes small, and thus the residual vibration at the time of stopping becomes small. Therefore, when M3 ≤ SH3, if the band-stop filter 311 is set to ON, the increase amount of the operation time T1 exceeds the decrease amount of the vibration convergence time T2, and there is a high possibility that the cycle time increases instead. Therefore, when M3 ≤ SH3, the band-stop filter 311 is set to OFF. Thereby, the increase of the cycle time is suppressed, and the operation efficiency of the robot system 1 is improved. In addition, the specified value SH3 is preferably set to a value such that the increase amount of the operation time T1 and the decrease amount of the vibration convergence time T2 are substantially equal.

[0098] Condition F: As Figure 5 shown, the case of correcting the operation instruction of the robotic arm 22 based on the output of the sensor 6 mounted on the horizontal articulated robot 2. That is, the case of controlling the drive of the robotic arm 22 based on the output of the sensor 6 mounted on the horizontal articulated robot 2.

[0099] If the band-stop filter 311 is set to ON, the acceleration decreases by removing the frequency component Hf from the position command P0, and correspondingly, the movement locus of the robotic arm 22 shifts. Therefore, it is difficult to finely control the position of the robotic arm 22 based on the output of the sensor 6. Therefore, the matching between the position control that feeds back the output of the sensor 6 and the use of the band-stop filter 311 is poor. In this case, the selector 312 sets the band-stop filter 311 to OFF. In addition, although there is no particular limitation on the sensor 6, for example, a force sensor 61 that detects the force applied to the workpiece W, an acceleration sensor 62 that detects the acceleration of the robotic arm 22, and an angular velocity sensor 63 that detects the angular velocity of the robotic arm 22 can be cited. In addition, Figure 5 illustrates, as an example, a circuit that feeds back the detection signal of the angular velocity sensor 63.

[0100] Above, Conditions A to F have been described. Next, a control method of the horizontal articulated robot 2 based on the control device 3 will be described. As Figure 6As shown, the control method includes: a control mode determination step S11 of determining whether the received motion instruction Sd is in the PTP control mode; and a determination step S12 of determining whether it is a first case where at least one of conditions A to F is satisfied or a second case where all of them are not satisfied. Further, in the second case, it further includes: a frequency component determination step S13 of determining the frequency component Hf removed from the position instruction P0 using the band-stop filter 311; a corrected control signal generation step S14 of removing the frequency component Hf from the position instruction P0 using the band-stop filter 311 to generate a corrected position instruction P1; and a first control step S15 of controlling the drive unit 26 according to the corrected position instruction P1. Further, in the first case, the frequency component determination step S13 and the corrected control signal generation step S14 are not performed, and it further includes a second control step S16 of controlling the drive unit 26 according to the position instruction P0.

[0101] Control mode determination step S11

[0102] In this step, first, as step S111, the control device 3 determines whether the motion instruction Sd is in the PTP control mode. When the motion instruction Sd is in the PTP control mode, as step S112, the control device 3 executes the motion instruction Sd. Since the acceleration of the robotic arm 22 is reduced by using the band-stop filter 311, the trajectory deviation caused by this movement occurs. Therefore, for example, control modes other than the PTP control mode, such as the CP control mode for controlling the movement path, have poor compatibility with the control method of the present embodiment. Therefore, here, the control method of the present embodiment is executed only in the case of the PTP control mode.

[0103] Determination step S12

[0104] In this step, the control device 3 determines whether the motion instruction Sd is a first case where at least one of conditions A to F is satisfied or a second case where all of conditions A to F are not satisfied.

[0105] Frequency component determination step S13

[0106] This step is executed when it is determined to be the second case in the determination step S12. In this step, first, as step S131, the control device 3 calculates the natural vibration frequency f0 of the posture of the robotic arm 22 at the end point Pe based on the posture of the robotic arm 22 at the end point Pe, the load weight M3, etc. Then, as step S132, the control device 3 determines the frequency component Hf removed using the band-stop filter 311 in a manner that includes the calculated natural vibration frequency f0.

[0107] Corrected control signal generation step S14

[0108] In this step, the control device 3 turns on the band-stop filter 311 to generate a corrected position command P1 obtained by removing the frequency component Hf from the position command P0.

[0109] First control step S15

[0110] In this step, the control device 3 controls the drive unit 26 based on the corrected position command P1. That is, the current command E0 generated based on the corrected position command P1 is supplied to the drive unit 26 to drive and control the servo motor 26A.

[0111] Second control step S16

[0112] In this step, the control device 3 turns off the band-stop filter 311, directly outputs the position command P0 from the band-stop filter 311, and controls the drive unit 26 based on the position command P0. That is, the current command E0 generated based on the position command P0 is supplied to the drive unit 26 to drive and control the servo motor 26A.

[0113] As described above, by controlling the ON / OFF of the band-stop filter 311 and using the band-stop filter 311 only when an operation command for improving the operation efficiency is achieved using the band-stop filter 311, it is possible to improve the operation efficiency of the robot system 1.

[0114] The robot system 1 has been described above. As described above, such a robot system 1 includes: a horizontal multi-joint robot 2 having a robot arm 22 equipped with an end effector 4 and a drive unit 26 for driving the robot arm 22; and a control device 3 for controlling the drive unit 26 based on a position command P0 as a control signal. Further, the control device 3 determines whether it is a first case where at least one of the conditions A to E is satisfied or a second case where all are not satisfied. In the first case, the drive unit 26 is controlled based on the position command P0. In the second case, the frequency component Hf removed from the position command P0 by using the band-stop filter 311 is determined, and the band-stop filter 311 is used to remove the frequency component Hf from the position command P0 to generate a corrected position command P1 as a corrected control signal, and the drive unit 26 is controlled based on the generated corrected position command P1. With this configuration, the band-stop filter 311 is used only when an operation command for improving the operation efficiency is achieved using the band-stop filter 311. Therefore, an increase in the cycle time can be suppressed, and the operation efficiency of the robot system 1 can be improved.

[0115] In addition, as described above, there is also a condition F, where the case where at least one of the conditions A to F is satisfied is set as the first case, and the case where all are not satisfied is set as the second case. Thereby, an increase in the cycle time can be more reliably controlled, and the operation efficiency of the robot system 1 can be improved.

[0116] In addition, as described above, before determining the frequency component Hf, the control device 3 determines whether it is the first case or the second case. Thereby, it becomes easy to control the drive unit 26.

[0117] In addition, as described above, the control device 3 controls the horizontal multi-joint robot 2 based on the position command P0 as a control signal. The horizontal multi-joint robot 2 includes a robotic arm 22 to which an end effector 4 is attached and a drive unit 26 that drives the robotic arm 22. The control device 3 determines whether it is the first case where at least one of the conditions A to E is satisfied or the second case where all of them are not satisfied. In the first case, the drive unit 26 is controlled based on the position command P0. In the second case, the frequency component Hf to be removed from the position command P0 using the band-stop filter 311 is determined, the frequency component Hf is removed from the position command P0 using the band-stop filter 311, a corrected position command P1 as a corrected control signal is generated, and the drive unit 26 is controlled based on the generated corrected position command P1. With this configuration, the band-stop filter 311 is used only when the band-stop filter 311 is used to implement an operation command for improving the operation efficiency. Therefore, an increase in the cycle time can be suppressed, and an improvement in the operation efficiency of the robot system 1 can be achieved.

[0118] In addition, as described above, the control method of the horizontal multi-joint robot 2 based on the control device 3 is as follows: The horizontal multi-joint robot 2 is controlled based on the position command P0 as a control signal. The horizontal multi-joint robot 2 includes a robotic arm 22 to which an end effector 4 is attached and a drive unit 26 that drives the robotic arm 22. This control method has a determination step S12 that determines whether it is the first case where at least one of the conditions A to E is satisfied or the second case where all of them are not satisfied. In the case of the second case, it further includes: a frequency component determination step S13 that determines the frequency component Hf to be removed from the position command P0 using the band-stop filter 311; a corrected control signal generation step S14 that removes the frequency component Hf from the position command P0 using the band-stop filter 311 and generates a corrected position command P1 as a corrected control signal; and a first control step S15 that controls the drive unit 26 according to the corrected position command P1. With this control method, the band-stop filter 311 is used only when the band-stop filter 311 is used to implement an operation command for improving the operation efficiency. Therefore, an increase in the cycle time can be suppressed, and an improvement in the operation efficiency of the robot system 1 can be achieved.

[0119] In addition, as described above, the control method includes a second control step S16 of controlling the drive unit 26 according to the position command P0 in the first case. Thereby, the control in the first case becomes easy.

[0120] In addition, as described above, there is also a condition F. A case where at least one of the conditions A to F is satisfied is set as the first case, and a case where all of them are not satisfied is set as the second case. Thereby, it is possible to more reliably suppress an increase in the cycle time and improve the operation efficiency of the robot system 1.

[0121] <Second Embodiment>

[0122] Figure 7 It is a flowchart showing a control method of a horizontal multi-joint robot according to the second embodiment.

[0123] The robot system 1 of the present embodiment is mainly the same as the robot system 1 of the above-described first embodiment except for the control method of the horizontal multi-joint robot 2 based on the control device 3. In addition, in the following description, regarding the present embodiment, the description will be centered on the differences from the above-described embodiment, and the same matters will be omitted. In addition, in Figure 7 the same reference numerals are assigned to the same components as those in the above-described embodiment.

[0124] As Figure 7 shown, the control method of the horizontal multi-joint robot 2 of the present embodiment includes: a control mode determination step S21 of determining whether the received motion command Sd is a PTP control mode; a frequency component determination step S22 of determining a frequency component Hf removed from the position command P0 using the band-stop filter 311; a corrected control signal generation step S23 of removing the frequency component Hf from the position command P0 using the band-stop filter 311 to generate a corrected position command P1; and a control step S24 of controlling the drive unit 26 according to the position command P0 in a first case where at least one of the conditions A to F is satisfied, and controlling the drive unit 26 according to the corrected position command P1 in a second case where all of them are not satisfied.

[0125] Control mode determination step S21

[0126] In this step, first, as step S211, the control device 3 determines whether the motion command Sd is a PTP control mode. When the motion command Sd is a PTP control mode, as step S212, the control device 3 executes the motion command Sd.

[0127] Frequency component determination step S22

[0128] In this step, first, as step S221, the control device 3 calculates the natural vibration frequency f0 of the posture of the end point Pe of the horizontal multi-joint robot 2 based on the posture of the robotic arm 22 at the end point Pe, the load weight M3, etc. Then, as step S222, the control device 3 determines the frequency component Hf in a manner including the calculated natural vibration frequency f0.

[0129] Correction control signal generation step S23

[0130] In this step, the control device 3 turns on the band-stop filter 311, removes the frequency component Hf from the position command P0, generates a corrected position command P1, and outputs the generated corrected position command P1.

[0131] Control step S24

[0132] In this step, as step S241, the control device 3 determines whether it is the first case where at least one of the conditions A to F is satisfied or the second case where none of the conditions A to F is satisfied. In the first case, as step S242, the control device 3 turns off the band-stop filter 311, does not use the corrected position command P1 generated in the correction control signal generation step S23, and drives and controls the drive unit 26 using the position command P0. On the contrary, in the second case, as step S243, the drive unit 26 is driven and controlled using the corrected position command P1 generated in the correction control signal generation step S23.

[0133] Thus, after generating the corrected position command P1, the control device 3 of the present embodiment determines whether it is the first case or the second case. Even with this method, it is easy to control the horizontal multi-joint robot 2.

[0134] As described above, by controlling the ON / OFF of the band-stop filter 311 and using the band-stop filter 311 only when the operation command for improving the operation efficiency is achieved using the band-stop filter 311, it is possible to improve the operation efficiency of the robot system 1.

[0135] As described above, in the robot system 1 of the present embodiment, after generating the corrected position command P1, the control device 3 determines whether it is the first case or the second case. With this method, it is also easy to control the horizontal multi-joint robot 2.

[0136] In addition, as described above, the control method of the horizontally articulated robot 2 based on the control device 3 is as follows: the horizontally articulated robot 2 is controlled based on the position command P0 as a control signal. The horizontally articulated robot 2 includes a robotic arm 22 to which an end effector 4 is attached and a drive unit 26 that drives the robotic arm 22. This control method includes: a frequency component determination step S22 of determining the frequency component Hf removed from the position command P0 using the band-stop filter 311; a corrected control signal generation step S23 of removing the frequency component Hf from the position command P0 using the band-stop filter 311 to generate a corrected position command P1 as a corrected control signal; and a control step S24 of controlling the drive unit 26 according to the position command P0 in a first case where at least one of conditions A to E is satisfied, and controlling the drive unit 26 according to the corrected position command P1 in a second case where all of them are not satisfied. According to this control method, the band-stop filter 311 is used only when an operation command for improving the operation efficiency is implemented using the band-stop filter 311. Therefore, an increase in the cycle time can be suppressed, and an improvement in the operation efficiency of the robot system 1 can be achieved.

[0137] As described above, the robot system, control device, and control method of the present invention have been described for the illustrated embodiments, but the present invention is not limited thereto. In addition, each part constituting the robot system can be replaced with any configuration capable of performing the same function. In addition, any constituent object can be added.

[0138] Hereinafter, the hardware configuration of the robot system will be described. Figure 8 The overall configuration of a robot system 1A to which a horizontally articulated robot 2, a controller 51, and a computer 52 are connected is shown. The control of the horizontally articulated robot 2 can be executed by a processor located in the controller 51 reading an instruction located in the memory, or can be executed by a processor existing in the computer 52 reading an instruction located in the memory and via the controller 51. Therefore, either one or both of the controller 51 and the computer 52 can be regarded as the "control device 3".

[0139] In addition, Figure 9 The overall configuration of a robot system 1B in which a computer 53 is directly connected to the horizontally articulated robot 2 is shown. The control of the horizontally articulated robot 2 is directly executed by a processor existing in the computer 53 reading an instruction located in the memory. Therefore, the computer 53 can be regarded as the "control device 3".

[0140] In addition, Figure 10Fig. shows the overall configuration of a robot system 1C in which a horizontal articulated robot 2 with a built-in 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 control of the horizontal articulated robot 2 can be executed by a processor existing in the computer 55 reading instructions located in the memory, or by a processor existing on the cloud 57 reading instructions located in the memory via the computer 55. Therefore, any one or any two or all three of the controller 54, the computer 55, and the cloud 57 can be regarded as the "control device 3".

Claims

1. A robot system, characterized in that, It has: A horizontally articulated robot having a robotic arm with an end effector attached thereto and a drive unit for driving the robotic arm; and A control device that controls the drive unit based on a control signal. In the control device, It is determined whether it is a first case or a second case, where the first case is that at least one of the following conditions A to E is satisfied, and the second case is that all of the conditions A to E are not satisfied. In the first case, the drive unit is controlled based on the control signal. In the second case, the frequency component to be removed from the control signal using a band-stop filter is determined, the frequency component is removed from the control signal using the band-stop filter, and a corrected control signal is generated, and the drive unit is controlled based on the generated corrected control signal. Condition A: It has a first drive mode and a second drive mode, and the robotic arm is driven in the second drive mode, and the upper limit value of the acceleration of the robotic arm is smaller in the second drive mode than in the first drive mode. Condition B: The separation distance between the center of gravity of the end effector and the tip of the robotic arm is equal to or greater than a specified value. Condition C: The end point of the movement of the robotic arm is unknown. Condition D: In the case where the robotic arm has an arm and an axis that moves up and down in the vertical direction with respect to the arm, the protrusion amount of the axis from the arm in the vertical direction is equal to or less than a specified value. Condition E: The sum of the weight of the end effector and the weight of the workpiece held by the end effector is equal to or less than a specified value.

2. The robot system according to claim 1, characterized in that, It further has the following Condition F. Condition F: The drive of the robotic arm is controlled based on the output of a sensor mounted on the horizontally articulated robot. The case where at least one of the conditions A to F is satisfied is set as the first case, and the case where all of them are not satisfied is set as the second case.

3. The robot system according to claim 1 or 2, characterized in that, Before determining the frequency component, the control device determines whether it is the first case or the second case.

4. The robot system according to claim 1 or 2, characterized in that, After generating the corrected control signal, the control device determines whether it is the first case or the second case.

5. A control device, characterized in that, A horizontally articulated robot is controlled based on a control signal, where the horizontally articulated robot has a robotic arm with an end effector attached thereto and a drive unit for driving the robotic arm. In the control device, It is determined whether it is a first case or a second case, where the first case is that at least one of the following conditions A to E is satisfied, and the second case is that all of the conditions A to E are not satisfied. In the first case, the drive unit is controlled based on the control signal. In the second case, the frequency component to be removed from the control signal using a band-stop filter is determined, the frequency component is removed from the control signal using the band-stop filter, and a corrected control signal is generated, and the drive unit is controlled based on the generated corrected control signal. Condition A: It has a first drive mode and a second drive mode, and the robotic arm is driven in the second drive mode, and the upper limit value of the acceleration of the robotic arm is smaller in the second drive mode than in the first drive mode. Condition B: The separation distance between the center of gravity of the end effector and the front end of the robotic arm is equal to or greater than a specified value; Condition C: The end point of the movement of the robotic arm is unknown; Condition D: When the robotic arm has an arm and an axis that moves up and down in the vertical direction with respect to the arm, the amount of protrusion of the axis in the vertical direction from the arm is equal to or less than a specified value; Condition E: The total weight of the end effector and the workpiece held by the end effector is equal to or less than a specified value.

6. A control method, characterized in that, Controlling a horizontal articulated robot based on a control signal, wherein the horizontal articulated robot includes a robotic arm equipped with an end effector and a drive unit that drives the robotic arm, The control method includes: A frequency component determination step of determining the frequency component to be removed from the control signal using a band-stop filter; A corrected control signal generation step of removing the frequency component from the control signal using the band-stop filter and generating a corrected control signal; A determination step of determining whether it is a first case or a second case, where the first case is that at least one of the following Conditions A to E is satisfied, and the second case is that all of Conditions A to E are not satisfied; and A control step of, in the first case, controlling the drive unit according to the control signal, and in the second case, controlling the drive unit according to the corrected control signal, Condition A: Having a first drive mode and a second drive mode, driving the robotic arm in the second drive mode, and the upper limit value of the acceleration of the robotic arm in the second drive mode is smaller than that in the first drive mode; Condition B: The separation distance between the center of gravity of the end effector and the front end of the robotic arm is equal to or greater than a specified value; Condition C: The end point of the movement of the robotic arm is unknown; Condition D: When the robotic arm has an arm and an axis that moves up and down in the vertical direction with respect to the arm, the amount of protrusion of the axis in the vertical direction from the arm is equal to or less than a specified value; Condition E: The total weight of the end effector and the workpiece held by the end effector is equal to or less than a specified value.

7. The control method according to claim 6, characterized in that, It further has the following Condition F, Condition F: Controlling the drive of the robotic arm based on the output of a sensor mounted on the horizontal articulated robot, Regarding the case where at least one of Conditions A to F is satisfied as the first case, and the case where all are not satisfied as the second case.

8. A control method, characterized in that, Controlling a horizontal articulated robot based on a control signal, wherein the horizontal articulated robot includes a robotic arm equipped with an end effector and a drive unit that drives the robotic arm, The control method has a determination step of determining whether it is a first case or a second case, where the first case is that at least one of the following Conditions A to E is satisfied, and the second case is that all of Conditions A to E are not satisfied, In the second case, further execute: A frequency component determination step of determining the frequency component to be removed from the control signal using a band-stop filter; A corrected control signal generation step of removing the frequency component from the control signal using the band-stop filter and generating a corrected control signal; and The first control step is to control the driving unit according to the calibration control signal. In the first case, a second control step is further performed. The second control step controls the driving unit according to the control signal. Condition A: It has a first driving mode and a second driving mode. The robotic arm is driven in the second driving mode, and the upper limit value of the acceleration of the robotic arm in the second driving mode is smaller than that in the first driving mode. Condition B: The separation distance between the center of gravity of the end effector and the front end of the robotic arm is equal to or greater than a specified value. Condition C: The end point of the movement of the robotic arm is unknown. Condition D: When the robotic arm has an arm and an axis that moves up and down in the vertical direction relative to the arm, the protrusion amount of the axis from the arm in the vertical direction is equal to or less than a specified value. Condition E: The total weight of the end effector and the workpiece held by the end effector is equal to or less than a specified value.

9. The control method according to claim 8, characterized in that, It also has the following Condition F. Condition F: The driving of the robotic arm is controlled based on the output of the sensor mounted on the horizontal articulated robot. The case where at least one of the conditions A to F is satisfied is set as the first case, and the case where all of them are not satisfied is set as the second case.

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