WO2023007634A1 - ロボットシステム - Google Patents

ロボットシステム Download PDF

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Publication number
WO2023007634A1
WO2023007634A1 PCT/JP2021/027965 JP2021027965W WO2023007634A1 WO 2023007634 A1 WO2023007634 A1 WO 2023007634A1 JP 2021027965 W JP2021027965 W JP 2021027965W WO 2023007634 A1 WO2023007634 A1 WO 2023007634A1
Authority
WO
WIPO (PCT)
Prior art keywords
torque
time
series data
robot system
reduction mechanism
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2021/027965
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
直幹 藤岡
一貴 若林
慶太 巣山
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fanuc Corp
Original Assignee
Fanuc Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fanuc Corp filed Critical Fanuc Corp
Priority to JP2023537831A priority Critical patent/JP7772797B2/ja
Priority to US18/567,152 priority patent/US20240278428A1/en
Priority to CN202180100747.2A priority patent/CN117651632A/zh
Priority to DE112021007501.2T priority patent/DE112021007501T5/de
Priority to PCT/JP2021/027965 priority patent/WO2023007634A1/ja
Priority to TW111126929A priority patent/TW202315730A/zh
Publication of WO2023007634A1 publication Critical patent/WO2023007634A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Program-controlled manipulators
    • B25J9/10—Program-controlled manipulators characterised by positioning means for manipulator elements
    • B25J9/104—Program-controlled manipulators characterised by positioning means for manipulator elements with cables, chains or ribbons
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Program-controlled manipulators
    • B25J9/16—Program controls
    • B25J9/1674—Program controls characterised by safety, monitoring, diagnostic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J13/00—Controls for manipulators
    • B25J13/08—Controls for manipulators by means of sensing devices, e.g. viewing or touching devices
    • B25J13/085—Force or torque sensors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J13/00—Controls for manipulators
    • B25J13/08—Controls for manipulators by means of sensing devices, e.g. viewing or touching devices
    • B25J13/087—Controls for manipulators by means of sensing devices, e.g. viewing or touching devices for sensing other physical parameters, e.g. electrical or chemical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J13/00—Controls for manipulators
    • B25J13/08—Controls for manipulators by means of sensing devices, e.g. viewing or touching devices
    • B25J13/088—Controls for manipulators by means of sensing devices, e.g. viewing or touching devices with position, velocity or acceleration sensors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Program-controlled manipulators
    • B25J9/10—Program-controlled manipulators characterised by positioning means for manipulator elements
    • B25J9/102—Gears specially adapted therefor, e.g. reduction gears
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Program-controlled manipulators
    • B25J9/16—Program controls
    • B25J9/1628—Program controls characterised by the control loop
    • B25J9/163—Program controls characterised by the control loop learning, adaptive, model based, rule based expert control
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Program-controlled manipulators
    • B25J9/16—Program controls
    • B25J9/1628—Program controls characterised by the control loop
    • B25J9/1653—Program controls characterised by the control loop parameters identification, estimation, stiffness, accuracy, error analysis
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M13/00—Testing of machine parts
    • G01M13/02—Gearings; Transmission mechanisms
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H1/00—Toothed gearings for conveying rotary motion
    • F16H1/02—Toothed gearings for conveying rotary motion without gears having orbital motion
    • F16H1/04—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members
    • F16H1/06—Toothed gearings for conveying rotary motion without gears having orbital motion involving only two intermeshing members with parallel axes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H57/00—General details of gearing
    • F16H57/01—Monitoring wear or stress of gearing elements, e.g. for triggering maintenance
    • F16H2057/018—Detection of mechanical transmission failures
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B2219/00—Program-control systems
    • G05B2219/30—Nc systems
    • G05B2219/40—Robotics, robotics mapping to robotics vision
    • G05B2219/40599—Force, torque sensor integrated in joint

Definitions

  • This disclosure relates to a robot system.
  • Patent Document 1 A method for detecting an abnormality in a motor and a speed reducer from the torque generated by the drive current of the motor (see Patent Document 1, for example).
  • One aspect of the present disclosure includes a robot including one or more joints, and a determination unit connected to the robot, wherein the joints include a motor, a speed reduction mechanism that reduces rotation of the motor, and the speed reduction mechanism.
  • a torque sensor capable of measuring an output torque of a mechanism; the speed reduction mechanism having a plurality of speed reduction elements that reduce rotation of the motor at a predetermined speed reduction ratio; time-series data of the number of revolutions of the motor, time-series data of the calculated input torque, time-series data of the output torque measured by the torque sensor, and each of the deceleration
  • the robot system determines the deceleration element having a problem based on the deceleration ratio of the element.
  • FIG. 1 is an overall configuration diagram showing a robot system according to a first embodiment of the present disclosure
  • FIG. 2 is a diagram showing a first rotary joint of the robot and a control device in the robot system of FIG. 1
  • FIG. 3 is a schematic diagram showing an example of a speed reduction mechanism in the first rotary joint shown in FIG. 2
  • 2 is a block diagram illustrating a control device of the robot system of FIG. 1
  • FIG. FIG. 5 is a diagram explaining a reduction gear ratio stored in a determination unit in FIG. 4
  • FIG. 2 is a flow chart explaining a diagnostic method in the robot system of FIG. 1
  • 7 is a flowchart following the flowchart of FIG. 6
  • FIG. 7 is a time chart for explaining time-series data of motor rotation speed and torque used in the diagnostic method of FIG. 6;
  • FIG. FIG. 7 is a block diagram illustrating a control device for a robot system according to a second embodiment of the present disclosure;
  • FIG. 10 is a flow chart illustrating a diagnostic method in the robot system of FIG. 9;
  • FIG. 11 is a time chart for explaining time series data of torque used in the diagnostic method of FIG. 10;
  • FIG. FIG. 11 is a flow chart describing a diagnostic method in a robot system according to a third embodiment of the present disclosure;
  • FIG. FIG. 13 is a schematic diagram illustrating a configuration of a robot of the robot system of FIG. 12;
  • FIG. 13 is an example of a speed reduction mechanism in the robot system of FIG.
  • FIG. 12 is a diagram showing an example of a mechanical component requiring a load and an example of the position of the load;
  • 2 is a schematic diagram illustrating a modification of the position of a torque sensor in the robot system of FIG. 1;
  • FIG. 11 is a schematic diagram illustrating another modification of the position of the torque sensor in the robot system of FIG. 1;
  • a robot system 1 according to a first embodiment of the present disclosure will be described below with reference to the drawings.
  • a robot system 1 according to the present embodiment includes a robot 2 and a control device (determination unit) 3 connected to the robot 2, as shown in FIG.
  • the robot 2 is, for example, a vertical 6-axis multi-joint type robot including 6 rotary joints (joints) J1, J2, J3, J4, J5, and J6.
  • the robot 2 includes a base 4 installed on the floor, and a swing body 5 rotatably supported relative to the base 4 about a vertical first axis A.
  • the robot 2 includes a first arm 6 rotatably supported with respect to the revolving barrel 5 about a horizontal second axis B, and a third axis C parallel to the second axis B. and a second arm 7 rotatably supported relative thereto.
  • the robot 2 also has a three-axis wrist unit 8 attached to the tip of the second arm 7 .
  • the wrist unit 8 includes a first wrist element 30 rotatably supported with respect to the second arm 7 about a fourth axis D orthogonal to the third axis C, and a fifth axis E orthogonal to the fourth axis D. a second wrist element 31 rotatably supported with respect to the first wrist element 30 and a sixth axis F orthogonal to the fourth axis D and the fifth axis E rotatably with respect to the second wrist element 31 and a supported third wrist element 32 .
  • the first rotary joint J1 comprises a pair of joint members consisting of a base 4 and a swivel barrel 5 that are rotatably supported around the first axis A.
  • the first rotary joint J1 also includes a servomotor (motor) 9 fixed to the base 4, which is one of the joint members, and a speed reduction mechanism 10 arranged between the pair of joint members.
  • the first rotary joint J1 is provided with a torque sensor 11 arranged between the speed reduction mechanism 10 and the swinging barrel 5, which is the other joint member, and capable of detecting torque applied between the two.
  • the servomotor 9 has a motor shaft 12 that is rotationally driven and an encoder 13 that detects the rotation angle of the motor shaft 12 .
  • the deceleration mechanism 10 is a mechanism for decelerating the rotation of the motor shaft 12 and transmitting it to the other joint member, and includes a plurality of deceleration elements 14, 15, 16 connected in series or in parallel.
  • the reduction mechanism 10 may have any configuration, for example, as shown in FIG. 3, it will be described as having three reduction elements 14, 15 and 16 connected in series.
  • a first reduction element (reduction element) 14 includes a first gear 17 fixed to the motor shaft 12 of the servomotor 9, a second gear 18 meshing with the first gear 17, and a first shaft to which the second gear 18 is fixed. and a first bearing (bearing) 20 that rotatably supports 19 about its longitudinal axis.
  • the second reduction element (reduction element) 15 includes a third gear 21 fixed to the first shaft 19, a fourth gear 22 meshing with the third gear 21, and a second shaft 23 to which the fourth gear 22 is fixed. It also has a second bearing (bearing) 24 that supports it rotatably around its longitudinal axis.
  • the third reduction element (reduction element) 16 includes a fifth gear 25 fixed to the second shaft 23, a sixth gear 26 meshing with the fifth gear 25, and a third shaft 27 to which the sixth gear 26 is fixed.
  • a third bearing (bearing) 28 is provided to rotatably support the shaft about its longitudinal axis.
  • the third shaft 27 is fixed to the output flange 29 of the speed reduction mechanism 10, and the torque sensor 11 is fixed to the flange surface 29a of the output flange 29.
  • a reduction ratio between the first gear 17 and the second gear 18 is a reduction ratio R1
  • a reduction ratio between the third gear 21 and the fourth gear 22 is a reduction ratio R2
  • a reduction ratio between the fifth gear 25 and the sixth gear 26 is is the reduction ratio R3.
  • the rotation speed N of the motor shaft 12 of the servomotor 9 is reduced to N/R1 by the first reduction element 14, reduced to N/(R1 ⁇ R2) by the second reduction element 15, and reduced to N by the third reduction element 16. /(R1 ⁇ R2 ⁇ R3). That is, the reduction ratio of the first reduction element 14 as seen from the servo motor 9 side is R1, the reduction ratio of the second reduction element 15 as seen from the servo motor 9 side is R1 ⁇ R2, and the servo of the third reduction element 16 is The reduction ratios seen from the motor 9 side are R1, R2, and R3.
  • the second rotary joint J2 has a structure similar to that of the first rotary joint J1 except that the pair of joint members is the swing barrel 5 and the first arm 6 .
  • the third rotary joint J3 also has the same structure as the first rotary joint J1 except that the pair of joint members is the first arm 6 and the second arm 7 .
  • the fourth rotary joint J4 also has a structure similar to that of the first rotary joint J1 except that the pair of joint members is the second arm 7 and the first wrist element 30 .
  • the fifth rotational joint J5 also has the same structure as the first rotational joint J1 except that the pair of joint members is the first wrist element 30 and the second wrist element 31 .
  • the sixth rotational joint J6 also has the same structure as the first rotational joint J1 except that the pair of joint members is the second wrist element 31 and the third wrist element 32 .
  • the control device 3 includes at least one processor and at least one memory. As shown in FIG. 4, the controller 3 controls the servo by feedback of rotation angle values from the encoders 13 provided in the servomotors 9 of the rotary joints J1, J2, J3, J4, J5, and J6. It includes a robot control section 33 that supplies a command current to the motor 9, a determination section 34, and a notification section 35.
  • the determination unit 34 receives the command current value output from the robot control unit 33, the rotation angle value output from the encoder 13 of the servo motor 9, and the measured torque Ts, which is the output torque detected by the torque sensor 11. is entered.
  • the determination unit 34 stores the speed reduction ratios R1, R2 and R3 of the speed reduction elements 14, 15 and 16 as shown in FIG. Based on the command current value input from the robot control unit 33, the determination unit 34 calculates the input torque input from the servomotor 9 to the speed reduction mechanism 10, and from the input torque and the reduction ratios R1, R2, R3, An ideal torque Ti, which is an ideal output torque of the speed reduction mechanism 10, is calculated.
  • the determination unit 34 calculates a difference torque TD1 by subtracting the actually measured torque Ts from the calculated ideal torque Ti. Furthermore, the determination unit 34 calculates the frequency f of the periodic component included in the differential torque TD1 by frequency-analyzing the differential torque TD1 by a known technique such as FFT.
  • the determination unit 34 determines the value N/f obtained by dividing the rotation speed N of the motor shaft 12 based on the amount of change in the rotation angle value detected by the encoder 13 by the calculated frequency f, and the reduction ratio 1 , R1, R1.R2, R1.R2.R3. As a result of the comparison, if the difference between the value N/f and one of the reduction ratios 1, R1, R1 ⁇ R2, R1 ⁇ R2 ⁇ R3 is within a predetermined threshold value, the determination unit 34 It is determined that there is a possibility that the deceleration elements 14, 15, 16 are malfunctioning.
  • the notification unit 35 notifies the result of determination by the determination unit 34 to the outside.
  • the method of notification by the notification unit 35 may be arbitrary, and it is possible to notify the outside of the location where there is a possibility of failure by display on the monitor of the control device 3, display by a lamp, or display by a buzzer.
  • a worker operates the control device 3 to operate the robot 2 .
  • the motion of the robot 2 may be any motion that simultaneously or plurally operates the six rotary joints J1, J2, J3, J4, J5, and J6. It is preferable to run a diagnostic program that activates J4, J5 and J6 one by one. Since the diagnostic method for each of the rotary joints J1, J2, J3, J4, J5, and J6 is the same, the diagnostic method for the first rotary joint J1 will be described here as an example.
  • the operator executes the diagnostic program to start constant-speed operation of only the first rotary joint J1 of the robot 2 (step S1).
  • the servomotor 9 is operated by the command current value output from the robot control unit 33 , and the swing drum 5 is rotationally driven around the first axis A with respect to the base 4 .
  • the rotation angle value detected by the encoder 13 of the servomotor 9 is input to the determination unit 34, and the determination unit 34 obtains the number of rotations N of the servomotor 9 from the change in the rotation angle value over time (step S2).
  • the command current value output from the robot control unit 33 is input to the determination unit 34, and the determination unit 34 calculates the ideal torque Ti based on the input torque of the servomotor 9 (step S3).
  • the ideal torque Ti is calculated by multiplying the input torque by the reduction ratios R1, R2, and R3 of the entire speed reduction mechanism 10 and the transmission efficiency.
  • the actually measured torque Ts detected by the torque sensor 11 is input to the determination section 34 (step S4).
  • the acquired rotation speed N, the calculated ideal torque Ti, and the detected actual torque Ts are stored in association with the input time of the rotation angle value, the command current value, and the actual measurement torque Ts to the determination unit 34 (step S5).
  • step S6 it is determined whether or not the motion of the robot 2 has ended (step S6), and if it has not ended, the steps from step S2 are repeated.
  • step S6 when it is determined that the operation of the robot 2 for diagnosis has been completed, as shown in FIG. of time-series data is acquired. Further, as shown in FIG. 7, by subtracting the time series data of the actually measured torque Ts from the time series data of the ideal torque Ti, the time series data of the differential torque (first differential torque) TD1 shown in FIG. obtain (step S7).
  • step S8 It is determined whether or not a differential torque TD1 exceeding a predetermined threshold value Th1 is generated in the acquired time-series data of the differential torque TD1 (step S8). If there is a time at which the differential torque TD1 exceeding the threshold Th1 is generated, as shown in FIG. 7, the frequency f of the periodic component included in the time series data of the differential torque TD1 is extracted (step S9 ).
  • a value N/f is calculated by dividing the rotational speed N of the servomotor 9 by the extracted frequency f (step S10).
  • the calculated value N/f is sequentially compared with the reduction ratios 1, R1, R1 ⁇ R2, R1 ⁇ R2 ⁇ R3 (steps S11 to S14).
  • step S11 If it is determined in step S11 that the value N/f is equal to 1 (the difference between the value N/f and 1 is smaller than the predetermined threshold value Th2), the servomotor 9 rotating at the rotation speed N and There is a possibility that there is a problem with the first gear 17 (step S15). If the rotor of the servomotor 9 has some kind of problem or the teeth of the first gear 17 are missing, the output torque fluctuates at the same frequency as the rotation speed N. If it is determined that there is a possibility of malfunction, the notification unit 35 notifies the outside (step S19).
  • step S12 If it is determined in step S11 that the value N/f is different from 1, whether the value N/f is equal to R1 (the difference between the value N/f and R1 is smaller than a predetermined threshold Th2) is determined (step S12). If it is determined in step S12 that the value N/f is equal to R1, there is a problem with the second gear 18 and the third gear 21 fixed to the first shaft 19 rotating at the number of revolutions N/R1. There is a possibility (step S16). In this case also, the notification unit 35 notifies the outside (step S19).
  • step S12 when it is determined in step S12 that the value N/f is different from R1, the value N/f is equal to R1 ⁇ R2 (the difference between the value N/f and R1 ⁇ R2 is a predetermined threshold value Th2 is smaller than) is determined (step S13).
  • step S13 the fourth gear 22 and the fifth gear fixed to the second shaft 23 rotating at the number of revolutions N/(R1 ⁇ R2)
  • the notification unit 35 notifies the outside (step S19).
  • step S13 when it is determined in step S13 that the value N/f is different from R1 ⁇ R2, the value N/f is equal to R1 ⁇ R2 ⁇ R3 (the value N/f and R1 ⁇ R2 ⁇ R3 It is determined whether or not the difference is smaller than a predetermined threshold Th2 (step S14). If it is determined in step S14 that the value N/f is equal to R1 ⁇ R2 ⁇ R3, then the sixth gear fixed to the third shaft 27 rotating at the number of revolutions N/(R1 ⁇ R2 ⁇ R3) 26 may be defective (step S18). In this case also, the notification section 35 notifies the outside (step S19).
  • the threshold Th2 in steps S11 to S14 may be the same or different. After the diagnosis of the first rotational joint J1 is completed, the diagnosis of the second rotational joint J2 to the sixth rotational joint J6 may be sequentially performed.
  • failure factors inside the speed reduction mechanism 10, that is, the speed reduction elements 14, 15, and 16 provided inside the speed reduction mechanism 10, rather than failures of the speed reduction mechanism 10 as a whole has the advantage of being able to identify defects in As a result, it is possible to replace the deceleration elements 14, 15 and 16 identified as defective without removing the entire deceleration mechanism 10 and reexamining it, or replacing the deceleration mechanism 10 as a whole. It can be minimized, and the man-hours and costs required for maintenance can be greatly reduced.
  • the determination can be made in the same way when there is a problem with other mechanical elements. For example, if there is a problem with the first bearing 20 that supports the first shaft 19, it is conceivable that the output torque will oscillate at a frequency that is the same as or similar to the number of revolutions N/R1. You may decide to
  • the output torque will oscillate at a frequency that is the same as or similar to the number of revolutions N/R1 and R2. may be determined. Also, if there is a problem with the third bearing 28 that supports the third shaft 27, it is conceivable that the output torque will oscillate at a frequency that is the same as or similar to the rotational speeds N/R1, R2, and R3. It is also possible to determine the defect by
  • the control device 3 includes a storage section 36 for storing time-series data of the reference torque TR.
  • the reference torque TR is a differential torque between the ideal torque Ti and the measured torque Ts when the robot 2 is in a normal state, which is acquired at the time of shipment of the robot 2 or the like.
  • time-series data of the differential torque TD1 obtained by executing steps up to step S7 in FIG.
  • the determination unit 34 subtracts the time-series data of the reference torque TR read from the storage unit 36 from the calculated time-series data of the differential torque TD1. Thereby, as shown in FIG. 10, time-series data of the difference value (second difference torque) TD2 is calculated (step S21).
  • the relationship between the difference torque TD1, the reference torque TR and the difference value TD2 is as shown in FIG. 11, for example.
  • the determination unit 34 determines, for example, whether or not the absolute value of the average value of the difference values TD2 exceeds a predetermined threshold Th3 (step S22). If the absolute value of the average value of the difference values TD2 exceeds the threshold value Th3, it is determined that there is a problem with any of the bearings 20, 24, 28 or the lubricant inside the speed reduction mechanism 10, and the notification unit 35 informs that effect. is notified (step S23).
  • the differential torque TD1 is a resistance component inside the speed reduction mechanism 10 obtained by subtracting the measured torque Ts from the ideal torque Ti, and varies depending on the preload amount of the bearings 20, 24, and 28 and the state of the lubricant.
  • the difference value TD2 indicates how much the current difference torque TD1 has changed from the normal state of the robot 2 by subtracting the reference torque TR from the difference torque TD1.
  • the speed reduction mechanism 10 includes a belt. There is a possibility that a problem such as a decrease in belt tension has occurred.
  • the average value of the difference values TD2 is positive, the following possibilities are conceivable. That is, clogging of mechanical parts such as bearings 20, 24, and 28 with abrasion powder of mechanical parts such as bearings 20, 24, and 28 due to deterioration of grease, which is a lubricant, and mechanical parts such as gears 17, 18, 21, 22, 25, and 26. clogging of the bearings 20, 24, and 28 with debris from the bearings, or hardening of the grease due to abrasion powder.
  • any one of the bearings 20, 20 inside the reduction mechanism 10 there is an advantage that it is possible to notify that a problem has occurred in 24, 28 or the lubricant.
  • the preload adjustment of the bearings 20, 24, 28 can improve the rigidity and rotational accuracy of the rotary joints J1, J2, J3, J4, J5, J6.
  • the problem can be repaired by replacing the lubricant without replacing other mechanical parts, greatly reducing man-hours and costs required for maintenance work. can be done.
  • the possibility that there is a problem with the bearings 20, 24, 28 or the lubricant is notified depending on whether or not the absolute value of the average value of the difference values TD2 is greater than the predetermined threshold value Th3.
  • the sign of the average value of the difference values TD2 may be used to more finely classify and notify the content of the defect.
  • the determination unit 34 determines the possibility of malfunction based on the absolute value of the average value of the difference values TD2. Instead, based on the time-series data of the difference value TD2 calculated in step S21 and the time-series data of the stored rotation angle value, the rotation joints J1, J2, J3, J4, J5, and J6 are calculated. Time-series data of the difference value TD2 in the time period when the movement of the rotary joints J1, J2, J3, J4, J5, and J6 is moving at a constant speed may be extracted.
  • the possibility of malfunction may be determined based on the difference value TD2 in the extracted time period.
  • the maximum value of the difference value TD2 in the time period when the rotary joints J1, J2, J3, J4, J5, and J6 start to move is an aperiodic component, which is the resistance component due to the static friction of the mechanical parts. Yes.
  • the absolute value of the maximum value of the difference value TD2 in the time period when the rotary joints J1, J2, J3, J4, J5, and J6 start to move exceeds a predetermined threshold Th3, the bearings 20, 24, and 28 It can be seen that the amount of preload is too large.
  • the average value of the difference values TD2 in the time period during which the rotary joints J1, J2, J3, J4, J5, and J6 are operating at constant speed is also an aperiodic component, and is a resistance component due to dynamic friction of mechanical parts. Yes.
  • the absolute value of the average value of the difference values TD2 in the time period during which the rotary joints J1, J2, J3, J4, J5, and J6 are operating at a constant speed exceeds a predetermined threshold value Th3, lubricant It can be seen that it is softening or hardening due to deterioration.
  • the time-series data of the difference value TD2 in the time period when the rotary joints J1, J2, J3, J4, J5, and J6 are operating at a constant speed may be used for extracting the frequency in step S9.
  • the frequency of the periodic component included in the differential torque TD1 can be reduced more than in the case of using the time-series data of the differential torque TD1 in all time zones during the operation of the rotary joints J1, J2, J3, J4, J5, and J6. It can be obtained with high precision.
  • the difference value TD2 is calculated by subtracting the time series data of the reference torque TR from the time series data of the difference torque TD1. Since the reference torque TR is, for example, the difference torque TD1 measured by executing the diagnostic program under predetermined conditions at the time of shipment of the robot 2, the diagnosis at the site can be performed under the same conditions as at the time of shipment. preferable.
  • a temperature sensor capable of detecting the temperature of the speed reduction mechanism 10 is provided, and the determination unit 34 is provided with a correction unit that corrects the time-series data of the reference torque TR based on the temperature detected by the temperature sensor.
  • a temperature detected by a temperature sensor provided in the torque sensor 11 may be used instead of using a temperature sensor that directly detects the temperature of the speed reduction mechanism 10.
  • the storage unit 36 may store the time-series data of the reference torque TR and the time-series data of the rotation angle value when the reference torque TR is measured.
  • each rotary joint J1, J2, J3, J4 calculated from the rotation angle value detected by the encoder 13 provided to each rotary joint J1, J2, J3, J4, J5, J6 at each moment. , J5 and J6 may be used to correct the reference torque TR to generate time-series data of the reference torque TR for the operation at the time of diagnosis.
  • the rotation joints J1, J2, J3, J4, J5, and J6 start to move and the rotation joints J1, J2, J3, J4, J5, and J6 operate at a constant speed.
  • the resistance components due to static friction and dynamic friction were used to determine the failure.
  • it may be used to measure the rotational smoothness of the speed reduction mechanism 10 . Since the change in the internal resistance of the speed reduction mechanism 10 is known, it is possible to estimate the state of lubrication, gears 17, 18, 21, 22, 25, 26, shaft center deflection due to wear of the bearings 20, 24, 28, etc. . Further, when a belt exists in the reduction mechanism 10, the belt tension can also be estimated.
  • the time zone and The time-series data of the difference value TD2 during the time period during which the rotary joints J1, J2, J3, J4, J5, and J6 are operating at a constant speed are extracted.
  • another encoder is attached to the output position of each deceleration mechanism 10, and the time period when the rotary joints J1, J2, J3, J4, J5, and J6 start to move and the rotary joints J1, J2, J3, and J4 are calculated.
  • J5 and J6 are operating at a constant speed.
  • a force sensor may be employed instead of the torque sensor 11 attached to the output position of the reduction mechanism 10 of each of the rotary joints J1, J2, J3, J4, J5, and J6.
  • FIG. 12 illustrates a case where the diagnosis by the robot system according to the present embodiment is performed during the diagnosis by the robot system 1 according to the first embodiment.
  • the control device 3 includes a storage section 36 connected to the determination section 34, as in the second embodiment shown in FIG.
  • the storage unit 36 stores the main dimensions of each link member (swivel barrel 5, first arm 6, second arm 7 and wrist unit 8) constituting the robot 2 and the output position of each reduction mechanism 10 (the center of the output flange 29). position coordinates) are stored. Further, the storage unit 36 stores, for each mechanical component in each speed reduction mechanism 10, a coefficient for calculating a second load to a third load, which will be described later, a threshold value of force and moment when the mechanical component begins to be affected, and A limit time is stored for which the threshold is allowed to be exceeded.
  • the coefficients, threshold values, and limit times are stored as values corresponding to the forces Fx, Fy, and Fz in the mutually orthogonal three-axis x, y, and z directions and the moments Mx, My, and Mz about the respective axes. All of the total six axial directions, or a plurality of forces and moments, are hereinafter collectively referred to as loads.
  • the directions of the three axes x, y, and z are set for each speed reduction mechanism 10 .
  • the determination unit 34 estimates the first load applied to the distal end of the wrist unit 8 of the robot 2 (center position of the flange surface of the wrist flange). (Step S31). At this time, the first load is estimated from the differential torque TD1 for a plurality of axes of the robot 2 . Next, the determination unit 34 determines the second load applied from the first load to the output position (the center position of the flange surface 29a of the output flange 29) of the speed reduction mechanism 10 of each of the rotary joints J1, J2, J3, J4, J5, and J6. A load is estimated (step S32). Next, the determination unit 34 estimates the third load applied to the mechanical parts constituting each reduction mechanism 10 from the second load for each of the rotary joints J1, J2, J3, J4, J5, and J6 (step S33). .
  • the first to third loads are estimated as time-series data.
  • the determining unit 34 determines the possibility of failure in which mechanical component based on the time-series data representing the third load of each mechanical component and the time-series data of the differential torque TD1 calculated in the first embodiment or the second embodiment. (step S34). Then, when it is determined that there is a problem with any of the mechanical parts, the notification unit 35 notifies that effect (step S35).
  • the diagnosis method in the robot system the case where the structure of the robot 2 is the structure shown in FIG. 13 and the external force X acts in the direction indicated by the arrow in FIG. explain.
  • the first load is estimated based on the actually measured torque Ts detected by the three torque sensors 11 at the second rotary joint J2, the third rotary joint J3, and the fifth rotary joint J5 (step S31).
  • the determination unit 34 determines the tip position of the wrist unit 8 using the rotation angle value from the encoder 13 and the main dimensions of each link member (swivel barrel 5, first arm 6, second arm 7, and wrist unit 8).
  • the first load is estimated based on the calculated wrist tip position, the output position of each deceleration mechanism 10, and the measured torque Ts.
  • the first load is estimated as (Fx, Fy, Fz, Mx, My, Mz) from forces in three orthogonal axial directions and moments around each axis. The same is true if other forces and moments act on the robot 2 .
  • the determination unit 34 calculates a coordinate transformation matrix for converting from the coordinate system of the tip of the wrist unit 8 to the coordinate system of the output position of each reduction mechanism 10, and uses the calculated coordinate transformation matrix and the first load.
  • the second load applied to the output position of each speed reduction mechanism 10 is calculated (step S32).
  • the determination unit 34 multiplies the second load by the coefficient stored in the storage unit 36 to calculate the third load applied to each mechanical component as time-series data (step S33).
  • third gears are located at the center positions P1 to P6 of the first gear 17 to the sixth gear 26 and the center positions P7 to P10 of the first bearing 20 to the third bearing 28. Calculate load time series data.
  • step S34 the determination unit 34 compares the time-series data of the third load applied to each mechanical component with the time-series data of the differential torque TD1 calculated in step S7 along the time axis. Accordingly, the determination unit 34 can determine that there is a possibility that a malfunction has occurred in the mechanical component fluctuating at the same frequency f as the differential torque TD1.
  • step S34 the determining unit (lifetime estimating unit) 34 integrates the time during which the estimated third load exceeds the threshold value stored in the storage unit 36. Then, the determination unit 34 estimates the remaining life of the mechanical component based on the accumulated time and the limit time stored in the storage unit 36 . Then, the notification unit 35 notifies the estimated remaining life of the mechanical component. As a result, it is possible to inform the outside of the mechanical components that are highly likely to cause a problem before the problem occurs.
  • the possibility of malfunction is determined by comparing the time-series data of the third load with the time-series data of the differential torque TD1.
  • the frequency of the periodic component is extracted by performing frequency analysis using FFT or the like on the time-series data as the third load acquired for all mechanical parts, and the frequency of the periodic component of the differential torque TD1 is calculated as the frequency of the periodic component. It may be determined that the mechanical component having the matching frequency is defective.
  • the mechanical component for which the possibility of failure is notified according to the third embodiment may be notified as additional information in addition to the notification of the failure in the first embodiment or the second embodiment.
  • the determination unit 34 notifies the user or the determination unit 34 to operate the mechanical component at a speed at which the malfunction of the mechanical component is likely to be conspicuous. The operating speed of the robot 2 may be adjusted by .
  • the determination unit 34 compares the time-series data of the differential torque TD1 with the time-series data of the third load in each mechanical component to identify the mechanical component in which the malfunction has occurred.
  • the determination unit 34 may include a trained model obtained by learning the time-series data of the third load calculated when the speed reduction mechanism 10 is normal, such as at the time of shipment. Then, when the robot 2 operates, the calculated time-series data of the third load in each mechanical part is input to the learned model, and the rate of deviation from the third load in the normal state is calculated for each mechanical part. , a threshold value, or the like may be used to specify a mechanical component in which a problem has occurred.
  • each of the rotary joints J1, J2, J3, J4, J5, and J6 is provided with the torque sensor 11 was illustrated, but as shown in FIG.
  • a 6-axis force sensor 37 may be arranged between and the installation surface.
  • a force sensor 37 may be arranged at the distal end of the wrist unit 8 .
  • a vertical 6-axis articulated robot having six rotary joints J1, J2, J3, J4, J5, and J6 was illustrated.
  • a robotic system comprising a jointed robot, a robot with a different number of rotating joints, such as seven, or any other type of robot 2 may be employed.
  • translational joints may be provided instead of the rotary joints J1, J2, J3, J4, J5, and J6.

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  • Engineering & Computer Science (AREA)
  • Robotics (AREA)
  • Mechanical Engineering (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Manipulator (AREA)
PCT/JP2021/027965 2021-07-28 2021-07-28 ロボットシステム Ceased WO2023007634A1 (ja)

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JP2023537831A JP7772797B2 (ja) 2021-07-28 2021-07-28 ロボットシステム
US18/567,152 US20240278428A1 (en) 2021-07-28 2021-07-28 Robot system
CN202180100747.2A CN117651632A (zh) 2021-07-28 2021-07-28 机器人系统
DE112021007501.2T DE112021007501T5 (de) 2021-07-28 2021-07-28 Robotersystem
PCT/JP2021/027965 WO2023007634A1 (ja) 2021-07-28 2021-07-28 ロボットシステム
TW111126929A TW202315730A (zh) 2021-07-28 2022-07-18 機器人系統

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CN117651632A (zh) 2024-03-05
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DE112021007501T5 (de) 2024-04-04

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