Robot management system and management method

Abstract

The lifespan or strength of the housing that makes up the robot is managed. [Solution] The management system S comprises a robot 1 having a robot arm 11 and a base 12; an motion control unit 100a that sends and receives angle information of each joint JT in the robot arm 11 to and from the robot 1 when the robot 1 is operating; an estimation unit 100b that estimates the stress state generated in the frame 10 of the robot arm 11 or the base 12 when the robot 1 is operating, based on the angle information and specification information 102a indicating the specifications of the robot 1; and an association unit 100d that stores the stress state estimated by the estimation unit 100b in association with a time series.

Description

【Technical Field】 【0004】 , , , , , , 【0006】 , , , , , , 【0005】 , , , , , , , , 【0001】 The present disclosure relates to a robot management system and a management method. 【Background Art】 【0002】 Patent Document 1 discloses a control device for an industrial robot. The control device according to Patent Document 1 includes two means. The first means calculates and accumulates the life of a predetermined member for each sampling time. The second means displays the necessity of replacing or inspecting the predetermined member based on the comparison result between the accumulated value by the first means and a reference value. 【0003】 The predetermined member according to Patent Document 1 is a speed reducer or grease. The control device according to Patent Document 1 varies the calculation formula of the accumulated value according to the type of the predetermined member. By using the accumulated value, the life of the robot parts can be managed. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 7-124889 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 The inventors of the present application considered making the frame constituting the link or base of the robot a management target for life or strength. However, Patent Document 1 targets a speed reducer or grease for management. The technology disclosed in Patent Document 1 has a different management target and cannot meet the needs of the inventors of the present application. 【Means for Solving the Problems】 【0006】 The technology disclosed herein relates to a robot management system. The robot management system comprises a robot having a robot arm and a base supporting the robot arm; an motion control unit that transmits and receives angle information of each joint in the robot arm to and from the robot when the robot is in motion; an estimation unit that estimates the stress state generated in the frame of the robot arm or the base when the robot is in motion, based on the angle information and specification information indicating the specifications of the robot; and a storage unit that stores the stress state estimated by the estimation unit in association with a time series. 【0007】 The technology disclosed herein relates to a robot management system. The robot management system comprises a robot having a robot arm and a base supporting the robot arm; an motion control unit that transmits and receives angle information of each joint in the robot arm to and from the robot when the robot is in motion; an estimation unit that estimates the strain state that occurs in the frame of the robot arm or the base when the robot is in motion, based on the angle information and specification information indicating the specifications of the robot; and a storage unit that stores the strain state estimated by the estimation unit, or the stress state based on the strain state, in association with a time series. 【0008】 The technology disclosed herein relates to a robot management method using a robot having a robot arm and a base supporting the robot arm, a calculation unit for executing a program, and a storage unit for storing the results of the program execution by the calculation unit. In the robot management method, the calculation unit acquires angle information of each joint in the robot arm when the robot is in motion, the calculation unit estimates the stress state that occurs in the frame of the robot arm or the base when the robot is in motion based on the angle information and specification information indicating the specifications of the robot, and the calculation unit stores the estimated stress state in the storage unit in relation to a time series. [Effects of the Invention] 【0009】 The robot management system and management method described above can appropriately manage the lifespan or strength of the frame that constitutes the robot's links or base. [Brief explanation of the drawing] 【0010】 [Figure 1] Figure 1 is a schematic diagram of the robot management system. [Figure 2] Figure 2 is a block diagram of the management system. [Figure 3] Figure 3 is a flowchart illustrating an example of a management method. [Figure 4] Figure 4 is a flowchart illustrating the estimation process. [Figure 5] Figure 5 is a flowchart illustrating the estimation process. [Figure 6] Figure 6 illustrates the procedure for calculating the stress state. [Figure 7] Figure 7 is a flowchart illustrating the decision-making process. [Figure 8] Figure 8 is a corresponding diagram to Figure 4, showing a modified version of the estimation process. [Figure 9] Figure 9 is a diagram corresponding to Figure 1, showing the management system related to the modified example. [Figure 10] Figure 10 illustrates the relationship between stress states and time series. [Modes for carrying out the invention] 【0011】 The following describes an embodiment of the robot management system and management method. The following description is illustrative. 【0012】 <Management System> First, the overall configuration of the management system S will be explained, and then the configurations of robot 1 and robot controller 100 will be briefly described. 【0013】 (Overall structure) FIG. 1 is a schematic diagram of the management system S of the robot 1. The management system S manages the components of the robot 1. The robot 1 can be used for various applications such as the logistics field. 【0014】 As shown in FIG. 1, the management system S includes a serial link type robot 1 and a robot controller 100. The robot 1 is arranged on the installation surface F. 【0015】 (Robot 1) As shown in FIG. 1, the robot 1 includes an articulated robot arm 11, a base 12 that supports the robot arm 11, an end effector 13, and an actuator 14. As elements related to the actuator 14, the robot 2 further includes a reducer 15 and an encoder 16 as shown in FIG. 2. 【0016】 The robot arm 11 is an articulated arm. Specifically, the robot arm 11 is a multi-axis and vertically articulated robot arm. More specifically, the robot arm 11 has joints JT and links LN. The number of axes of the robot arm 11, that is, the number of joints JT, is not particularly limited. It is not essential that the robot arm 11 is articulated. 【0017】 The joints JT are connected in series from the base end to the tip end. The link LN is an arm connected to the joint JT. The link LN includes a link LN connecting the base 12 and the joint JT, a link LN connecting two joints JT, and a link LN connecting the joint JT and the end effector 13. 【0018】 The base 12 supports the robot arm 11 from below. Specifically, the base 12 supports one of the plurality of links LN from below. The link LN supported by the base 12 can be regarded as the base end of the robot arm 11. 【0019】 Each link LN has at least one housing. Stress acts on the housing of the link LN when the joint JT is driven. The housing is a metal frame 10. The housing is, for example, made of casting. 【0020】 The base 12 has at least one housing. Stress acts on the housing of the base 12 when the joint JT is driven. The housing is a metal frame. The housing is, for example, made of casting. 【0021】 Hereinafter, the chassis of the Link LN and the chassis of the Base 12 will be collectively referred to as Frame 10. In the following description, Frame 10 may refer to the chassis of a specific Link LN, the chassis of the Base 12, or both the chassis of the Link LN and the Base 12. 【0022】 The end effector 13 is the tip of the robot arm 11. The tip of the robot arm 11 is the end located on the opposite side from the connection point between the link LN and the base 12. The end effector 13 is, for example, a robot hand. However, the end effector 13 is not limited to a robot hand. The end effector 13 is electrically connected to, for example, a robot controller 100. 【0023】 The actuator 14 is a power source that moves the joint JT. For example, one actuator 14 is connected to one joint JT. As an example, the actuator 14 in this embodiment is an electric motor. The electric motor is, for example, a servo motor. The electric motor may also be a stepper motor. The actuator 14 is electrically connected to, for example, a robot controller 100. 【0024】 The reduction gear 15 increases the output torque of the electric motor by reducing the rotational speed of the electric motor acting as the actuator 14. For example, one reduction gear 15 is connected to one actuator 14. 【0025】 The encoder 16 detects the rotation angle of the electric motor acting as the actuator 14. The encoder 16 is, for example, an optical encoder including a light-receiving element and a light-emitting diode. However, the encoder 16 is not limited to an optical encoder. The encoder 16 is electrically connected to, for example, the robot controller 100. 【0026】 (Robot controller 100) The robot controller 100 is a computer equipped with a calculation unit 101, a storage unit 102, and an interface. The robot controller 100 inputs control signals to the robot 1. 【0027】 The arithmetic unit 101 reads a program from the storage unit 102. The arithmetic unit 101 executes the program read from the storage unit 102. Specifically, the arithmetic unit 101 is a combination of one or more processors. A processor is a central processing unit. 【0028】 The storage unit 102 stores the management program 300 executed by the arithmetic unit 101 and the execution results of the management program 300 by the arithmetic unit 101. Specifically, the storage unit 102 has volatile memory as main memory and non-volatile memory as auxiliary memory. The volatile memory is, for example, random access memory (RAM). The non-volatile memory is, for example, a combination of read-only memory (ROM) and storage. The storage may be a solid-state drive (SSD) or a hard disk drive (HDD). 【0029】 The program executed by the arithmetic unit 101 includes the management program 300 described below. The management program 300 is stored in a physical storage medium 400 that is computer-readable. The management program 300 can be stored in the storage unit 102 via the storage medium 400. In addition, the storage unit 102 has previously stored specification information 102a and matrix data 102b as information related to the management program 300. 【0030】 In addition, various data generated by the management program 300 are stored in the storage of the memory unit 102 or temporarily stored in RAM as main memory, as needed. 【0031】 As shown in Figure 2, the robot controller 100 includes a motion control unit 100a related to the movement of the robot 1. The motion control unit 100a sends and receives angle information to and from the robot 1 when the robot 1 is moving. 【0032】 More specifically, the motion control unit 100a inputs control signals to the robot arm 11 when the robot 1 is moving. More precisely, the motion control unit 100a inputs control signals as electrical signals to each actuator 14 of the robot arm 11. The control signals input to each actuator 14 include angle information of the joint JT corresponding to each actuator 14. The angle information indicates the rotation angle of the electric motor and, consequently, the joint JT. 【0033】 When a control signal is input, each actuator 14 rotates the corresponding joint JT to achieve the rotation angle corresponding to the angle information. The joint JT rotates around the central axis Ax of the reduction gear 15. By inputting a control signal to each joint JT, the robot arm 11 operates to achieve a predetermined posture. 【0034】 When the joint JT rotates in response to the input of a control signal, the encoder 16 outputs a detection signal indicating the rotation angle of the electric motor acting as the actuator 14, i.e., the angle information. The detection signal output from the encoder 16 is input to the motion control unit 100a of the robot controller 100 as an electrical signal indicating angle information for feedback control. 【0035】 The robot controller 100 performs feedback control on the robot arm 11 to suppress the discrepancy between the rotation angle corresponding to the control signal and the rotation angle corresponding to the detection signal. By repeatedly performing feedback control, the robot controller 100 enables the robot arm 11 to achieve the desired movement. 【0036】 The robot controller 100 also functions as a management device for the robot 1, capable of executing the management method according to this embodiment by executing the management program 300. 【0037】 As illustrated in Figure 2, the robot controller 100, as a management device, includes, separately from the motion control unit 100a, an estimation unit 100b that performs estimation processing, a determination unit 100c that performs determination processing, and an association unit 100d that performs processing related to the storage unit 102. 【0038】 <Management method> Next, the management method according to this embodiment will be described. 【0039】 Figure 3 is a diagram illustrating the management method. In step S1 of Figure 3, the robot controller 100 sets the number of iterations of the estimation process "i" to 1. In step S1, "i=1" is set. In the following step S2, the estimation unit 100b performs the estimation process as follows. 【0040】 Figures 4 and 5 are flowcharts illustrating the estimation process. Figures 4 and 5 are merely examples of the estimation process. For example, the execution order of steps S101 and S102 may be reversed, or the two processes may be performed in parallel. 【0041】 In this embodiment, the estimation unit 100b performs the estimation process illustrated in Figure 4 in order to estimate the stress state in the robot 1. During the estimation process, the estimation unit 100b estimates the stress state that occurs in the frame 10 of the robot 1 during the operation of the robot 1, based on the angle information and the specification information 102a. The estimation unit 100b performs the estimation process via the calculation unit 101. 【0042】 In step S101 of Figure 3, the estimation unit 100b reads specification information 102a from the storage unit 102. The specification information 102a shows the specifications of robot 1. More specifically, the estimation unit 100b refers to the center of gravity position and weight of the base 12, and the center of gravity position, weight and moment of inertia of each link LN as the specifications of robot 1. More specifically, the specifications of robot 1 include the center of gravity position, weight and moment of inertia of the end effector 13, in addition to the center of gravity position, weight and moment of inertia of the base 12 and each link LN. 【0043】 In the subsequent step S102, the estimation unit 100b acquires angle information of each joint JT in the robot arm 11 during the operation of the robot 1. The angle information acquired in step S102 may be obtained from control signals input from the robot controller 100 to the robot 1, or from electrical signals fed back from the robot 1 to the robot controller 100. 【0044】 In the subsequent step S103, the estimation unit 100b estimates the forces Fx, Fy, Fz in three spatial directions and the force moments Mx, My, Mz acting on the frame 10, in relation to the time series, based on the angle information and specification information 102a acquired in steps S102 and S103. 【0045】 Here, the spatial forces Fx, Fy, Fz and the force moments Mx, My, Mz are estimated at the component level of the robot 1. The components of the robot 1 are the base 12, the link LN, and the end effector 13. The estimation unit 100b may perform estimation for multiple components or for only one component. Furthermore, the spatial forces Fx, Fy, Fz and the force moments Mx, My, Mz can be estimated for each of the multiple link LNs. 【0046】 Here, the three spatial forces Fx, Fy, and Fz are composed of the force Fx in the x-direction, the force Fy in the y-direction, and the force Fz in the z-direction in the relative coordinate system as seen from the component being estimated. The term "relative coordinates" can be rephrased as the "local coordinates" of the corresponding component. 【0047】 Similarly, the moment of force Mx, My, Mz is composed of the moment of force Mx around the x-axis, the moment of force My around the y-axis, and the moment of force Mz around the z-axis in the aforementioned relative coordinate system. Hereafter, the term "moment of force" will be simply referred to as "moment." 【0048】 During the operation of robot 1, forces and moments act on the components of robot 1. In step S103, the estimation unit 100b estimates the forces and moments acting on the components of robot 1. 【0049】 Specifically, in step S103, the estimation unit 100b estimates the forces Fx, Fy, Fz and moments Mx, My, Mz in three spatial directions for one or more components of the link LN and base 12 to be estimated, based on an inverse dynamics calculation method. The inverse dynamics calculation method may be, for example, the Newton-Euler method, or any other method capable of calculating forces and moments. The angular information used for estimation may change over time. By estimating at each time point, the estimation of the forces Fx, Fy, Fz and moments Mx, My, Mz in three spatial directions can be performed in relation to the time series. 【0050】 In the subsequent step S104, the estimation unit 100b outputs the values ​​of each component in the stress tensor σ generated in the frame 10, based on the spatial forces Fx, Fy, Fz and moments Mx, My, Mz acting on the frame 10, as the stress state, associated with the time series. The stress state can be estimated and output separately for each estimation location. 【0051】 It is not mandatory for the estimation unit 100b to output the stress state. As shown in the deformation described later, it may output the strain state instead of the stress state. 【0052】 The stress tensor σ can be represented as a 3x3 matrix in three-dimensional space. The matrix representing the stress tensor σ is a symmetric matrix with six independent components. 【0053】 More specifically, the estimation unit 100b approximates and outputs the values ​​of each component in the stress tensor σ by a linear sum of the forces Fx, Fy, Fz and moments Mx, My, Mz in three spatial directions. 【0054】 In other words, the estimation unit 100b approximates the stress tensor σ linearly using six variables: the forces Fx, Fy, and Fz in three spatial directions and the moments Mx, My, and Mz around three axes, and outputs the approximate result of the stress tensor σ. 【0055】 It is not mandatory to approximate the stress tensor σ with a linear sum. Terms proportional to the square, cube, etc., of the six variables may be used, or a constant term independent of the six variables may be used. 【0056】 In this embodiment, the stress tensor σ is set at one or more points in the corresponding housing. The points where the stress tensor σ is set are the estimated positions of the stress tensor σ, which are set within or on the corresponding frame 10. The stress tensor σ at one or more estimated positions in the corresponding housing is output based on six variables: the forces Fx, Fy, Fz in three spatial directions and the moments Mx, My, Mz around three axes. 【0057】 The following processes are common to both cases where a specific estimated location is used and cases where all estimated locations are used. If multiple estimated locations are used, the processes exemplified below will be performed for each estimated location. 【0058】 To approximate the stress tensor σ by a linear sum of six variables, we can use the values ​​of each component of the stress tensor σ when a unit load is applied in the x, y, or z direction, and the values ​​of each component of the stress tensor σ when a unit moment is applied around the x, y, or z axis. 【0059】 The values ​​of each component required for approximating the stress tensor σ are used as constants multiplied by each variable in the first-order approximation for each estimated position. The constants multiplied by each variable are not scalar quantities, but multi-component constants described as a 3x3 matrix with 6 independent components. The multi-component constants multiplied by each variable are stored in the storage unit 102 in advance as the matrix data 102b. 【0060】 In step S104, the estimation unit 100b reads matrix data 102b from the storage unit 102 and outputs approximate values ​​for each component of the stress tensor σ by multiplying it by the forces Fx, Fy, Fz and moments Mx, My, Mz in three spatial directions. 【0061】 As shown in the upper part of Figure 6, let [σFx] be the value of each component when a unit load is applied in the x direction. Let [σFy] be the value of each component when a unit load is applied in the y direction. Let [σFz] be the value of each component when a unit load is applied in the z direction. Let [σMx] be the value of each component when a unit moment is applied around the x axis. Let [σMy] be the value of each component when a unit moment is applied around the y axis. Let [σMz] be the value of each component when a unit moment is applied around the z axis. As illustrated in the upper part of Figure 6, the value of each component can be described as a 3x3 matrix of 6 independent components. The value of each component is given for each estimated position. 【0062】 As shown in the middle of Figure 6, let Fx(ti) be the force in the x-direction at a predetermined operating timing ti. Let Fy(ti) be the force in the y-direction at a predetermined operating timing ti. Let Fz(ti) be the force in the z-direction at a predetermined operating timing ti. Let Mx(ti) be the moment around the x-axis at a predetermined operating timing ti. Let My(ti) be the moment around the y-axis at a predetermined operating timing ti. Let Mz(ti) be the moment around the z-axis at a predetermined operating timing ti. The values ​​of the forces and moments are given for every 10 frames. 【0063】 As shown in the lower part of Figure 6, the estimation unit 100b multiplies the values ​​of each component shown in the upper part of the same figure by the force and moment values ​​at a predetermined operating timing ti shown in the middle part of the same figure. The estimation unit 100b then organizes the multiplication results for the independent components of the matrix. By organizing the multiplication results, the estimation unit 100b calculates a stress tensor σ, which is described as a 3x3 matrix. The calculated values ​​of the stress tensor σ are given for each estimation position and for each operating timing ti, as shown in the upper part of Figure 10. The upper part of Figure 10 is a graph illustrating the process shown in the middle part of Figure 6. 【0064】 During the operation of robot 1, stresses corresponding to force and moment act on the frame 10 of robot 1. In step S104, the estimation unit 100b estimates the stress state occurring in the housing and outputs the estimated stress state in relation to a time series. 【0065】 Specifically, the estimation unit 100b performs the association between the stress state and the time series through the association between the stress state and the operation timing. The operation timing is a predetermined timing in the time series, which is none other than the timing at which stress acts on the housing as a result of the robot 1's operation. Hereinafter, the operation timing will be denoted as "ti" in relation to the number of repetitions. i is a natural number between 1 and N, and "N" is a parameter set in advance. 【0066】 The values ​​of each component of the stress tensor σ estimated by the estimation unit 100b in step S104 are stored in the storage unit 102 in the subsequent step S105, in association with the time series, as illustrated in the lower part of Figure 10. The lower part of Figure 10 is a graph illustrating the process shown in the lower part of Figure 6. 【0067】 The association with the time series and storage in the memory unit 102 are performed by the association unit 100d. The storage by the memory unit 102 may be temporary via RAM or the like, or it may be continuous via storage. 【0068】 In the subsequent step S106, the estimation unit 100b converts the stress tensor σ output in step S104 into principal stresses for each estimated position and for each operation timing ti along the time series. The principal stresses calculated in step S106 include the maximum principal stress, the minimum principal stress, and the intermediate principal stress. The conversion to principal stresses can be performed, for example, by diagonalizing the stress tensor σ. 【0069】 Note that conversion to principal stress is not mandatory. The lifespan or strength of the frame 10 may be controlled based on the time-dependent changes in each component of the stress tensor σ. 【0070】 In step S107 of Figure 5, which follows step S106, the estimation unit 100b calculates the stress amplitude, the mean stress, and the amplitude of the equivalent stress on both sides based on the principal stresses calculated in step S105. The stress amplitude can be calculated based on the maximum principal stress and the minimum principal stress. The mean stress can be calculated based on the maximum principal stress and the minimum principal stress. The amplitude of the equivalent stress on both sides can be calculated based on the stress amplitude and the mean stress. 【0071】 In addition, when performing the calculation in step S107, the estimation unit 100b may replace the maximum principal stress with the maximum value of the maximum principal stress calculated in each loop repeated through steps S3 and S4 in Figure 3, and then calculate based on the replaced maximum value. 【0072】 Similarly, when performing the calculation in step S107, the estimation unit 100b may replace the minimum principal stress with the minimum value of the minimum principal stress calculated in each loop repeated through steps S3 and S4 in Figure 3, and then calculate based on the replaced minimum value. 【0073】 In the subsequent step S108, the estimation unit 100b determines whether the amplitude of the equivalent stress of both sides calculated in step S107 exceeds a predetermined fatigue limit. The value of the fatigue limit is stored in the storage unit 102. The value of the fatigue limit is set in advance. 【0074】 If the determination in step S108 is NO, the estimation unit 100b transitions the control process from step S108 to step S110. If the determination in step S108 is YES, the estimation unit 100b transitions the control process from step S108 to step S109. 【0075】 In step S109, the estimation unit 100b outputs a warning via the notification unit 2. The notification unit 2 is connected to the robot controller 100 and notifies the user of the warning via sound, light, screen display, etc. After the warning is notified, the estimation unit 100b transitions the control process from step S109 to step S110. 【0076】 Note that transitioning the control process from step S109 to step S110 is not mandatory. After the processing in step S109, the robot controller 100 may stop the operation of the robot 1. The calculation of the equivalent stress on both sides, the processing in step S108, and the processing in step S109 are not mandatory. 【0077】 In step S110, the estimation unit 100b determines the stress waveform C(ti) at the operating timing ti based on the principal stress calculated in step S106. The stress waveform C(ti) is determined for each estimation position. The stress waveform C(ti) determined in step S109 is temporarily or continuously stored in the storage unit 102 as another example of the stress state. 【0078】 Once the process in step S110 is complete, the robot controller 100 terminates the estimation process illustrated in two parts in Figures 4 and 5. The robot controller 100 then proceeds with the control process from the estimation process shown in step S2 of Figure 3 to step S3 of the same figure. 【0079】 In step S3, the robot controller 100 determines whether the number of iterations i of the estimation process has reached N times, that is, whether "i=N" is successful. 【0080】 If the determination in step S3 is NO, the robot controller 100 proceeds to step S4 of the control process. In step S4, the robot controller 100 counts up the number of repetitions, i.e., "i = i + 1", and returns the control process to step S2. 【0081】 The robot controller 100 repeats the process of step S2, the determination of step S3, and the process of step S4 until the determination of step S3 is YES. By repeating the process of step S2, a total of N stress waveforms C(t1)-C(tN) are obtained. Hereafter, the total of N stress waveforms arranged in time series will be collectively referred to as "C(t)". 【0082】 If the determination in step S3 is YES, the robot controller 100 proceeds to step S5 of the control process. In step S5, the determination unit 100c performs the following determination process. 【0083】 Figure 7 is a flowchart illustrating the configuration of the judgment process. Figure 7 is only one example of a judgment process. For example, it is not necessary to execute steps S205 and S206 every time. Steps S205 and S206 may be performed only if the cumulative number of cumulative values, as described later, exceeds a predetermined number. 【0084】 In this embodiment, the determination unit 100c performs a stress state determination process to determine the stress state. During the determination process, the determination unit 100c calculates a determination index that characterizes the lifespan or strength of the frame 10 based on the stress state stored in association with a time series. The determination unit 100c performs the determination process via the calculation unit 101. 【0085】 In step S201 of Figure 6, the determination unit 100c reads the stress waveform C(t). If there are multiple estimated positions, the determination unit 100c reads the stress waveform C(t) for each of the multiple estimated positions. 【0086】 In the subsequent step S202, the determination unit 100c performs a stress frequency reading method on the stress waveform C(t) read in step S201, as preparation for applying the Minor's rule to the stress waveform C(t). The stress frequency reading method may be the rainflow method, the range pair method, or the range pair mean method. As an example, the rainflow method is used in this embodiment. 【0087】 Through the process in step S202, the determination unit 100c extracts, for example, the stress amplitude, the number of loads corresponding to the stress amplitude, and the mean stress from the stress waveform C(t). This extraction by the determination unit 100c can be performed for each of the multiple estimated positions. 【0088】 In the subsequent step S203, the determination unit 100c calculates the cumulative damage level as a determination index based on the Minor's rule and the physical quantities extracted by the stress frequency reading method. The term Minor's rule is used in a broad sense. The Minor's rule used in step S203 includes a modified Minor's rule that can calculate the fatigue life of the frame 10. 【0089】 In this embodiment, a modified Minor rule is used. Based on the intersection of the modified SN curve and the horizontal axis, the fatigue life of the frame 10 can be calculated. 【0090】 The management method shown in Figure 3 is executed repeatedly, for example, when robot 1 is operating. Each time the management method is executed, the cumulative damage level is calculated repeatedly. 【0091】 Therefore, in step S204, which follows step S203, the determination unit 100c accumulates the cumulative damage level each time the cumulative damage level is calculated in step S203. Each time the management method shown in Figure 3 is executed, the determination unit 100c accumulates the cumulative damage level that is calculated each time. 【0092】 In the subsequent steps S205 and S206, the determination unit 100c causes the notification unit 2 to issue a notification based on the cumulative value of the cumulative damage accumulated in step S204. 【0093】 Specifically, in step S205, the determination unit 100c calculates the fatigue life of the frame 10 based on the cumulative value. The fatigue life of the frame 10 can be calculated by a method that references the cumulative damage level. For example, the determination unit 100c calculates the fatigue life of the frame 10 using a model that references the cumulative value of the cumulative damage level. The model can be defined so that the calculated fatigue life becomes smaller as the cumulative value increases. 【0094】 In the subsequent step S206, the determination unit 100c determines whether the fatigue life calculated in step S205 is less than or equal to a predetermined specified value. The specified value is stored in the storage unit 102. The specified value is set in advance. 【0095】 If the determination in step S206 is NO, the determination unit 100c skips the processing in step S207 and proceeds to step S208 of the control process. If the determination in step S206 is YES, the determination unit 100c transitions the control process from step S206 to step S207. 【0096】 In step S207, the determination unit 100c outputs a warning via the notification unit 2. The notification unit 2 notifies the user of the warning via sound, light emission, screen display, etc. Note that outputting a warning via the notification unit 2 is not mandatory. A log file containing changes in the cumulative damage level may be stored in or overwritten in the storage unit 102 each time. 【0097】 In the subsequent step S208, the determination unit 100c stores the cumulative value calculated in step S204 in the storage unit 102. Once step S208 is completed, the determination unit 100c terminates the determination process. 【0098】 <Effects and Effects> Generally, the lifespan of the frame 10 is designed to exceed the product life of the robot 1 when used within its rated limits. However, depending on the application of the robot 1, situations where the robot 1 is used beyond its rated limits may be anticipated. When the robot 1 is used beyond its rated limits, the frame 10 will be subjected to greater forces and moments than when the robot 1 is used within its rated limits. As a result of these greater forces and moments, the strength or lifespan of the frame 10 may be limited. 【0099】 In response to the aforementioned possibility, in this embodiment, as illustrated in steps S104 and S105 of Figure 4, the stress state occurring in the frame 10 can be stored in association with a time series, thereby managing the change in the stress state over time. The lifespan or strength of the frame 10 is reflected in the behavior of the stress state. By managing the change in the stress state over time, the lifespan or strength of the frame 10 can be appropriately managed. 【0100】 Furthermore, as illustrated in Figure 2, by referring to the weight, center of gravity, and moment of inertia as specification information 102a, the forces and moments acting on the frame 10 can be appropriately estimated based on the Newton-Euler method, etc. By appropriately estimating the forces and moments, the values ​​of each component of the stress tensor σ generated in the frame 10 can be calculated with high accuracy. 【0101】 As described above, this disclosure is particularly useful in the stage prior to when the strength or lifespan of the frame 10 reaches its limit, that is, when the strength or lifespan has not yet reached its limit. The case in which the strength or lifespan of the frame 10 has not yet reached its limit corresponds to a case in which the forces and moments acting on the frame 10 are smaller than those that would occur when the strength or lifespan has reached its limit. 【0102】 On the other hand, the accuracy of the approximation by the linear sum of forces and moments of force in three spatial directions increases as the forces and moments of force become smaller. In situations where this disclosure is effective, the values ​​of each component of the stress tensor σ will be approximated with good accuracy. The approximation by linear sum reduces to a simpler approximation formula compared to approximations by other functional forms. By reducing to a simpler approximation formula, the calculation processing of the calculation unit 101 can be suppressed. 【0103】 Principal stresses are physical quantities that characterize the magnitude of normal stresses generated within a material. By using principal stresses, as illustrated in step S106 of Figure 4, the lifespan or strength of the frame 10 can be determined with high accuracy. 【0104】 The cumulative damage level is a physical quantity that characterizes the lifespan or strength of a material. As illustrated in step S203 of Figure 7, the cumulative damage level can be used to accurately determine the lifespan or strength of the frame 10. 【0105】 Furthermore, as illustrated in steps S204 and S205 of Figure 7, the lifespan or strength of the frame (10) can be accurately determined by using the cumulative value of the cumulative damage. 【0106】 <Variation> In the above embodiment, the determination unit 100c was configured to calculate the fatigue life based on the principal stress, but various processes related to fatigue life are not essential. For example, if the value of the stress tensor σ calculated by the estimation unit 100b, or the magnitude of the principal stress based on the stress tensor σ, exceeds a predetermined reference value, notification may be given via the notification unit 2. 【0107】 More generally, this disclosure does not require notification by the notification unit 2 or calculation of principal stresses by the estimation unit 100b. The management system S and management method related to this disclosure only need to store the stress state in association with a time series. The method of utilizing the stored stress state can be appropriately selected according to the administrator's purpose. 【0108】 For example, the strength of the frame 10 can be estimated based on the magnitude of the stress tensor σ value calculated by the estimation unit 100b. For instance, if the stress tensor σ value in the frame 10 is small, the strength of the frame 10 can be considered higher compared to when the stress tensor σ value is large. 【0109】 Furthermore, if multiple estimated locations are set, the calculation of principal stresses in the estimation process may be performed by selecting a representative point with relatively high stress and referring to the value of the stress tensor σ at the selected representative point. 【0110】 Similarly, if multiple estimated locations are set, the calculation of the cumulative damage degree in the judgment process may be performed by selecting a representative point with relatively high principal stress and referring to the principal stress value at the selected representative point. 【0111】 The timing for the estimation and determination processes can be set arbitrarily. For example, the estimation process may be executed in sync with the operation of robot 1, or it may be executed when robot 1 is not operating. Similarly, the determination process may be executed in sync with the operation of robot 1, or it may be executed when robot 1 is not operating. When robot 1 is not operating, this includes when robot 1 is in standby mode. 【0112】 When the estimation or determination process is performed when the robot 1 is not in operation, the estimation or determination process may be executed according to a schedule specified via the robot controller 100 or the like. For example, the estimation unit 100b may be started to perform the estimation process when angle information, or force and moment values ​​based on angle information, exceed a predetermined number. 【0113】 In the estimation process, the number of estimated positions can be arbitrarily changed. For example, estimated positions may be set across the entire frame 10, and the estimation process may be performed for all estimated positions, or the estimation process may be performed only for specific estimated positions. The same applies to the determination process. The number of estimated positions may differ between the estimation process and the determination process. 【0114】 Figure 8 is a corresponding diagram to Figure 4 showing a modified example of the estimation process. In Figure 8, the process shown in step S1001 is the same as the process in step S101 in Figure 4. Similarly, the process shown in step S1002 is the same as the process in step S102. Similarly, the process shown in step S1003 is the same as the process in step S103. In Figure 8, the process shown in step S1004 is different from the process in step S104. The process shown in step S1005 is different from the process in step S105. The process shown in step S1006 is different from the process in step S106. 【0115】 In the above embodiment, the estimation unit 100b was configured to output a stress tensor σ as a stress state, but this disclosure is not limited to the output of a stress tensor σ. The estimation unit 100b may also output a strain tensor σ as a strain state. 【0116】 Specifically, the estimation unit 100b in the modified version estimates the strain state that occurs in the frame 10 of the robot arm 11 or base 12 during the operation of the robot 1, based on angle information and specification information 102a indicating the specifications of the robot 1. The association unit 100d in the same modified version stores the strain state estimated by the estimation unit 100b, or the stress state based on the strain state, in the storage unit 102, after associating it with a time series. 【0117】 Here, the strain state may be, for example, the strain tensor ε. As is well known, strain and stress are proportionally related based on Hooke's Law. Monitoring the strain state has the same effect as monitoring the stress state. By storing the strain state in relation to a time series, the lifespan or strength of the frame 10 can be appropriately managed, just as if the stress state were stored. 【0118】 Furthermore, by pre-storing Young's modulus or elastic modulus as a proportionality constant in the memory unit 102, the strain state can be converted to a stress state. By converting to a stress state, the lifespan can be predicted based on the principal stress. 【0119】 Specifically, in step S1004 of Figure 8, the estimation unit 100b outputs the values ​​of each component of the strain tensor ε generated in the frame 10, based on the spatial forces Fx, Fy, Fz and moments Mx, My, Mz acting on the frame 10, as the strain state, in relation to the time series. The strain state can be estimated and output separately for each estimation position. The procedure for calculating the strain tensor ε is substantially the same as in step S104. The word "stress" in step S104 should be replaced with "strain" as appropriate. Similarly, the word "stress state" in Figure 6 should be replaced with "strain state," and the notation of the stress tensor "σ" in the same figure should be replaced with the strain tensor "ε." 【0120】 Specifically, to approximate the strain tensor ε by a linear sum of six variables, we can use the values ​​of each component of the strain tensor ε when a unit load is applied in the x, y, or z direction, and the values ​​of each component of the strain tensor ε when a unit moment is applied around the x, y, or z axis. 【0121】 The values ​​of each component required for approximating the strain tensor ε are used as constants multiplied by each variable in the first-order approximation for each estimation position. The constants multiplied by each variable are not scalar quantities, but multi-component constants described as a 3x3 matrix of 6 independent components. The multi-component constants multiplied by each variable are stored in the storage unit 102 in advance as the matrix data 102b. 【0122】 By preparing the matrix data 102b related to the modified form in advance, the values ​​of each component of the strain tensor ε generated in frame 10 can be output in step S1004. 【0123】 In step S1005, the values ​​of each component of the strain tensor ε estimated by the estimation unit 100b are stored in the storage unit 102 in association with the time series. The storage by the storage unit 102 may be temporary via RAM or the like, or it may be continuous via storage. When storing by the storage unit 102, the strain tensor ε may be converted to a stress tensor σ using the proportionality coefficient, and the converted stress tensor σ may be stored in the storage unit 102. 【0124】 In the subsequent step S1006, the estimation unit 100b converts the strain tensor ε output in step S1005 into a stress tensor σ. The estimation unit 100b converts the values ​​of each component of the converted stress tensor σ into principal stresses for each estimation position and for each operation timing ti along the time series. Except for the processing related to the conversion from strain tensor ε to stress tensor σ, the processing in step S1006 is substantially the same as that in step S106. 【0125】 Note that the processing related to the strain tensor ε is not limited to the example in Figure 8. For example, instead of converting the strain tensor ε to the stress tensor σ in step S1006, the strain tensor ε may be converted to the stress tensor σ in step S1004 or step S1005. 【0126】 Figure 9 is a diagram corresponding to Figure 1 showing a modified management system T. Figure 9 is the same as the management system S illustrated in Figure 1, except for the functional configuration of the robot controller 100, the fact that an external terminal 200 is connected to the robot controller 100, and the configuration related to the external terminal 200. 【0127】 As shown in Figure 9, an external terminal 200 is connected to the modified robot controller 100. The external terminal 200 is a computer equipped with a processor, memory, and input / output bus. The external terminal 200 has an estimation unit 100b and a determination unit 100c. In place of the illustrated example, the external terminal 200 may be equipped with either the estimation unit 100b or the determination unit 100c. 【0128】 In the configuration example shown in Figure 9, although the angle information is acquired by the robot controller 100, the estimation process based on the angle information and the judgment process based on the results of the estimation process are performed by the external terminal 200. 【0129】 As illustrated in Figure 9, it is not essential that the estimation and determination processes related to this disclosure be performed by the robot controller 100. The estimation and determination processes may be performed by another controller connected to the robot controller 100, a so-called system controller. 【0130】 The estimation and determination processes may be performed on an offline computer where the management program 300 is installed, after the angle information has been transferred to an external storage medium. 【0131】 The functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, dedicated processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuits. In this disclosure, a circuit, unit, or means is hardware that performs the enumerated functions, or hardware programmed to perform the enumerated functions. The hardware may be hardware disclosed herein, or other known hardware that is programmed or configured to perform the enumerated functions. If the hardware is a processor, which is considered a type of circuit, then the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or the processor. 【0132】 <Mode> The above embodiment is a specific example of the following embodiment. 【0133】 (Aspect 1) A robot (1) having a robot arm (11) and a base (12) that supports the robot arm (11), During the operation of the robot (1), a motion control unit (100a) transmits and receives angle information of each joint (JT) in the robot arm (11) to and from the robot (1), An estimation unit (100b) estimates the stress state generated in the frame (10) of the robot arm (11) or the base (12) during the operation of the robot (1), based on the angle information and specification information (102a) indicating the specifications of the robot (1). The system includes an association unit (100d) that stores the stress state estimated by the estimation unit (100b) in relation to a time series, Robot (1) management system (S,T). 【0134】 By storing the stress state occurring in the frame (10) of the robot arm (11) or base (12) in relation to a time series, the change in the stress state over time can be managed. The lifespan or strength of the frame (10) is reflected in the behavior of the stress state. By managing the change in the stress state over time, the lifespan or strength of the frame (10) can be appropriately managed. 【0135】 (Aspect 2) The estimation unit (100b) refers to the weight, center of gravity position, and moment of inertia of the robot arm (11) and the base (12) as the specification information (102a), The estimation unit (100b) also, Based on the angle information and the specification information (102a), the forces and force moments acting on the frame (10) in three spatial directions are estimated for each time step along the time series. Based on the forces and force moments acting on the frame (10) in the three spatial directions, the values ​​of each component of the stress tensor σ generated in the frame (10) are output as the stress state, in relation to the time series. A management system (S,T) for the robot (1) described in Embodiment 1. 【0136】 By referring to the weight, center of gravity, and moment of inertia, the forces and moments acting on the frame (10) can be appropriately estimated based on the Newton-Euler method, etc. By appropriately estimating the forces and moments, the values ​​of each component of the stress tensor σ generated in the frame (10) can be calculated with high accuracy. 【0137】 (Aspect 3) The estimation unit (100b) approximates and outputs the values ​​of each component of the stress tensor σ by a linear sum of the forces and force moments in the three spatial directions. A management system (S,T) for the robot (1) described in Embodiment 2. 【0138】 This disclosure is particularly useful when the strength or lifespan of the frame (10) has not reached its limit. The strength or lifespan of the frame (10) has not reached its limit, which corresponds to a situation where the forces and moments of force are smaller than those that would occur when the strength or lifespan has reached its limit. 【0139】 On the other hand, the accuracy of the approximation by the linear sum of the forces and moments of force in the three spatial directions increases as the forces and moments of force become smaller. In the context in which this disclosure is effective, the values ​​of each component of the stress tensor σ will be approximated with good accuracy. 【0140】 (Aspect 4) The system further includes a determination unit (102c) that determines the lifespan or strength of the frame (10) based on the stress state stored in association with the aforementioned time series, The estimation unit (100b) converts the stress tensor σ into principal stresses at each time step along the time series, The determination unit (102c) determines the lifespan or strength of the frame (10) based on the principal stress. A management system (S,T) for the robot (1) according to embodiment 2 or 3. 【0141】 Principal stresses are physical quantities that characterize the magnitude of normal stresses generated within a material. By using principal stresses, the lifespan or strength of the frame (10) can be determined with high accuracy. 【0142】 (Appendix 5) The system further comprises a notification unit (2) that performs notification based on the determination result of the determination unit (102c), The frame (10) is made of metal, The determination unit (102c) calculates the cumulative damage level based on the principal stress converted for each time step and Minor's rule. The notification unit (2) performs the notification based on the magnitude of the cumulative damage. A management system (S,T) for the robot (1) described in Embodiment 4. 【0143】 Cumulative damage is a physical quantity that characterizes the lifespan or strength of a material. By using cumulative damage, the lifespan or strength of the frame (10) can be determined with accuracy. 【0144】 (Aspect 6) The determination unit (102c) is The cumulative damage level is repeatedly calculated, Each time the cumulative damage level is calculated, the cumulative damage level is totaled, Based on the cumulative value of the cumulative damage level, the notification unit (2) is instructed to issue a notification. A management system (S,T) for the robot (1) described in Embodiment 5. 【0145】 By using the cumulative value of the cumulative degree of damage, the lifespan or strength of the frame (10) can be determined with high accuracy. 【0146】 (Aspect 7) A robot (1) having a robot arm (11) and a base (12) that supports the robot arm (11), During the operation of the robot (1), a motion control unit (100a) transmits and receives angle information of each joint (JT) in the robot arm (11) to and from the robot (1), An estimation unit (100b) estimates the distortion state that occurs in the frame (10) of the robot arm (11) or the base (12) when the robot (1) is operating, based on the angle information and specification information (102a) indicating the specifications of the robot (1). The system comprises an association unit (100d) that associates the strain state estimated by the estimation unit (100b), or the stress state based on the strain state, with a time series. Robot (1) management system (S,T). 【0147】 By storing the strain state occurring in the frame (10) of the robot arm (11) or base (12) in relation to a time series, the changes in the strain state over time can be managed. The lifespan or strength of the frame (10) is reflected in the behavior of the strain state. By managing the changes in the strain state over time, the lifespan or strength of the frame (10) can be appropriately managed. 【0148】 (Pattern 8) A robot (1) having a robot arm (11) and a base (12) that supports the robot arm (11), a calculation unit (101) that executes a program, and a storage unit (102) that stores the results of the program execution by the calculation unit (101), wherein the robot (1) is managed using the robot (1), The calculation unit (101) acquires angle information of each joint (JT) in the robot arm (11) when the robot (1) is in motion. The calculation unit (101) estimates the stress state generated in the frame (10) of the robot arm (11) or the base (12) during the operation of the robot (1), based on the angle information and the specification information (102a) indicating the specifications of the robot (1). The calculation unit (101) stores the estimated stress state in the storage unit (102) in association with a time series. A method for managing robot (1). 【0149】 By storing the stress state occurring in the frame (10) of the robot arm (11) or base (12) in relation to a time series, the change in the stress state over time can be managed. The lifespan or strength of the frame (10) is reflected in the behavior of the stress state. By managing the change in the stress state over time, the lifespan or strength of the frame (10) can be appropriately managed. [Explanation of symbols] 【0150】 S, T Management System 1 Robot 10 frames 11 Robot Arm 12 bass 100 Robot Controllers 101 Arithmetic section 100a Operation Control Unit 100b Estimation part 100c Judgment part 100d Association section 102 Storage section 2 Hochi Department 200 External terminals

Claims

[Claim 1] A robot having a robotic arm and a base that supports the robotic arm, During the operation of the robot, a motion control unit transmits and receives angle information of each joint in the robot arm to and from the robot, An estimation unit that estimates the stress state generated in the robot arm or the base frame during the operation of the robot, based on the angle information and specification information indicating the specifications of the robot. The system includes a correlation unit that stores the stress state estimated by the estimation unit in relation to a time series. A robot management system. [Claim 2] In the robot management system according to claim 1, The estimation unit refers to the weight, center of gravity, and moment of inertia of the robot arm and the base as specification information. The estimation unit also, Based on the angle information and the specification information, the forces and force moments acting on the frame in three spatial directions are estimated in relation to the time series. Based on the forces and force moments acting on the frame in the three spatial directions, the values ​​of each component of the stress tensor generated in the frame are output as the stress state, in relation to the time series. A robot management system. [Claim 3] In the robot management system according to claim 2, The estimation unit approximates and outputs the values ​​of each component of the stress tensor by a linear sum of the forces and force moments in the three spatial directions. A robot management system. [Claim 4] In the robot management system according to claim 2 or 3, The system further includes a determination unit that determines the lifespan or strength of the frame based on the stress state stored in association with the aforementioned time series. The estimation unit converts the stress tensor into principal stresses at each time step along the time series, The determination unit determines the lifespan or strength of the frame based on the principal stress. A robot management system. [Claim 5] In the robot management system according to claim 4, The system further includes a notification unit that performs notification based on the determination result of the determination unit, The aforementioned frame is made of metal, The determination unit calculates the cumulative damage level based on the principal stress converted at each time step and Minor's rule. The notification unit performs the notification based on the magnitude of the cumulative damage. A robot management system. [Claim 6] In the robot management system according to claim 5, The determination unit, The cumulative damage level is repeatedly calculated, Each time the cumulative damage level is calculated, the cumulative damage level is totaled, Based on the cumulative value of the cumulative damage level, the notification unit is instructed to issue a notification. A robot management system. [Claim 7] A robot having a robotic arm and a base that supports the robotic arm, During the operation of the robot, a motion control unit transmits and receives angle information of each joint in the robot arm to and from the robot, An estimation unit that estimates the distortion state that occurs in the robot arm or the base frame during the operation of the robot, based on the angle information and specification information indicating the specifications of the robot. The system includes an association unit that stores the strain state estimated by the estimation unit, or the stress state based on the strain state, in relation to a time series. A robot management system. [Claim 8] A robot management method comprising a robot having a robot arm and a base supporting the robot arm, a calculation unit for executing a program, and a storage unit for storing the results of the program execution by the calculation unit, The calculation unit acquires angle information of each joint in the robot arm during the operation of the robot. The calculation unit estimates the stress state generated in the robot arm or the base frame during the operation of the robot, based on the angle information and specification information indicating the specifications of the robot. The calculation unit stores the estimated stress state in the storage unit in relation to the time series. How to manage robots.

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