Tension estimation device, life evaluation device, and robot system

Abstract

Provided are a tension estimation device capable of accurately estimating belt tension, a life evaluation device capable of accurately evaluating the life of a transmission mechanism based on the belt tension, and a robot system including these devices. The tension estimation device includes: a transmission mechanism that transmits power via a belt; at least one motor disposed proximate to the belt; a motor heat generation calculation unit that calculates the motor heat generation based on at least one of the current value and rotational speed of the at least one motor; a friction heat generation calculation unit that calculates the friction heat generation of the transmission mechanism based on at least one of the current value and rotational speed of the at least one motor and the friction coefficient of at least one shaft disposed proximate to the belt; and a belt tension estimation unit that estimates the belt tension based on the motor heat generation and the friction heat generation.

Description

Technical Field

[0001] The present invention relates to a tension estimation device, a life evaluation device and a robot system. Background Art

[0002] In robots, it is important to estimate the lifespan of the robot's drive system to predict robot failures before they occur. For example, Patent Document 1 discloses that the lifespan of robot components can be accurately evaluated by estimating their temperature.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-8472 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] As a robot with multiple axes, such as a vertical multi-joint robot, there is a known robot that has a transmission mechanism that transmits the power of a motor to a movable part via a belt. In a robot whose transmission mechanism has a belt, if the temperature of the components constituting the robot rises due to the movement of the robot, the distance between the axes of the belt will increase due to the expansion of the components (mainly metals such as castings). As a result, there is a concern that the tension of the belt will increase, which will reduce the life of the drive system including the transmission mechanism. Therefore, in a machine that has a transmission mechanism that transmits the power of a motor to a movable part via a belt, it is necessary to estimate the life of the drive system based on the change in the tension of the belt caused by the movement.

[0008] Therefore, there is a demand for a tension estimation device capable of accurately estimating the tension of a belt, and a life evaluation device and a robot system capable of accurately evaluating the life of a transmission mechanism based on the belt tension.

[0009] Solutions for solving problems

[0010] One embodiment of the tension estimation device disclosed herein comprises: a transmission mechanism that transmits power via a belt; at least one motor, wherein the at least one motor is arranged close to the belt; a motor heat generation calculation unit that calculates the motor heat generation based on at least one of the current value and the rotational speed of the at least one motor; a friction heat generation calculation unit that calculates the friction heat generation of the transmission mechanism based on at least one of the current value, the rotational speed and the friction coefficient of at least one shaft arranged close to the belt; and a belt tension estimation unit that estimates the tension of the belt based on the motor heat generation and the friction heat generation.

[0011] One aspect of the life evaluation device disclosed herein includes: the tension estimation device; and a life estimation unit that estimates the life of the transmission mechanism based on the tension of the belt estimated by the tension estimation device.

[0012] One embodiment of the robot system disclosed herein comprises: a robot having multiple motors, multiple movable parts, and one or more transmission mechanisms, wherein the one or more transmission mechanisms transmit power of at least any one of the multiple motors to at least any one of the multiple movable parts via a belt; a control device that controls the multiple motors of the robot; and the life evaluation device.

[0013] Effects of the Invention

[0014] According to one embodiment, a tension estimation device capable of accurately estimating belt tension, a life evaluation device capable of accurately evaluating the life of a transmission mechanism based on the belt tension, and a robot system including these devices can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is an overall structural diagram showing one embodiment of a robot system.

[0016] Figure 2 Yes Figure 1 Figure 2 shows the internal structure of the second arm of the robot.

[0017] Figure 3 This is a block diagram showing the configuration of a first embodiment of a tension estimation device and a life evaluation device in a robot system.

[0018] Figure 4 This is a block diagram showing the configuration of a second embodiment of a tension estimation device and a life evaluation device in a robot system.

[0019] Figure 5 This is a block diagram showing the configuration of a third embodiment of a tension estimation device and a life evaluation device in a robot system.

[0020] Figure 6 This is a graph showing the relationship between the temperature of the transmission mechanism and the tension of the belt. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the tension estimation device, life evaluation device, and robot system disclosed in the present invention will be described in detail with reference to the accompanying drawings. Figure 1 As shown, the robot system 1 includes a robot 2 , a robot control device 3 for controlling the robot 2 , and a display unit 4 connected to the robot control device 3 .

[0022] The robot 2 of this embodiment is a vertical multi-jointed robot with multiple movable parts. Specifically, the robot 2 is a six-axis vertical multi-jointed robot with six movable axes: the J1 axis 2a, the J2 axis 2b, the J3 axis 2c, the J4 axis 2d, the J5 axis 2e, and the J6 axis 2f. The robot 2 includes a base 21 mounted on a floor surface, for example, a first revolving portion 22 mounted on the base 21, a first arm 23 mounted on the first revolving portion 22, a second revolving portion 24 mounted on the first arm 23, a second arm 25 mounted on the second revolving portion 24, and a wrist unit 26 mounted on the tip of the second arm 25.

[0023] The first convoluted portion 22 is rotatable horizontally relative to the base portion 21 via the J1 axis 2a. The first arm 23 is swung forward and backward relative to the first convoluted portion 22 via the J2 axis 2b. The second convoluted portion 24 is swung vertically relative to the first arm 23 via the J3 axis 2c. The second arm 25 is rotatable relative to the second convoluted portion 24 about an axis extending in the longitudinal direction of the second arm 25 via the J4 axis 2d. The wrist element 26 is swung vertically relative to the second arm 25 via the J5 axis 2e and is rotatable about an axis intersecting the J5 axis 2e via the J6 axis 2f.

[0024] The robot 2 has a motor for driving the J1 axis 2a to the J6 axis 2f on each axis (in Figure 1 (not shown) and a transmission mechanism for transmitting the power of the motor to each shaft. For example, Figure 2 The figure shows the interior of the second arm 25 of the robot 2. A J5-axis motor 5 is disposed inside the second arm 25 to swing the wrist unit 26 about the J5-axis 2e. The power of the J5-axis motor 5 is transmitted to the J5-axis 2e via a transmission mechanism 6.

[0025] The transmission mechanism 6 includes a first pulley 61 attached to the output shaft 5a of the J5-axis motor 5, a second pulley 62 attached to the J5 shaft 2e, a belt 63 stretched across the first and second pulleys 61 and 62, and a speed reducer 64 that reduces the rotation of the second pulley 62. The output shaft 5a and the J5 shaft 2e are rotatably supported by bearings (not shown). The bearings (not shown) in the transmission mechanism 6 have a lifespan that varies with changes in belt tension.

[0026] In addition, if Figure 2 As shown, a J6-axis motor 7 is also provided inside the second arm 25, which is close to the J5-axis motor 5 and is used to drive the J6-axis 2f. The power of the J6-axis motor 7 is transmitted to the J6-axis 2f via a transmission mechanism not shown. Figure 1As shown, a J4-axis motor 8 for driving the J4 axis 2 d is provided on the second winding portion 24 .

[0027] The life of the transmission mechanism of the robot 2 is affected by the temperature of the structural part where the transmission mechanism is arranged. Figure 2 In the case of the transmission mechanism 6 in the second arm 25 shown in the figure, the life of the transmission mechanism 6 is affected by the temperature of the second arm 25 itself. That is, when the temperature of the second arm 25 rises due to driving the robot 2, the components (mainly metal such as castings) constituting the second arm 25 expand, and Figure 2 The interaxial distance L between the output shaft 5a of the J5-axis motor 5 and the J5 shaft 2e increases. Consequently, the tension of the belt 63 increases, and the load applied to the first pulley 61 and the second pulley 62 increases. As a result, the life of the transmission mechanism 6 decreases.

[0028] The temperature rise of the structural parts of the robot 2 is caused not only by the heat generated by the motor arranged inside the structural part, but also by the heat generated by other structural parts arranged close to the structural part. Figure 2 In the case of the second arm 25 shown, the temperature rise of the second arm 25 is caused not only by the heat generated by the J5-axis motor 5 located within the second arm 25, but also by the heat generated by the J6-axis motor 7 driving the J6-axis 2f, and by frictional heat generated by the operation of the friction points, namely the J4-axis 2d, J5-axis 2e, and J6-axis 2f. Therefore, when estimating the tension of the belt 63 of the transmission mechanism 6 within the second arm 25 and the life of the transmission mechanism 6, it is necessary to also consider the heat generated by these components located close to the belt 63.

[0029] The robot control device 3 is electrically connected to the robot 2 and integrally controls the movements of the robot 2. The robot control device 3 includes a control device 31 that controls various components of the robot 2, such as the motor; a tension estimation device 32 that estimates the tension of the belt 63 provided in the transmission mechanism 6 of the robot 2; and a life evaluation device 33 that estimates the life of the transmission mechanism 6 of the robot 2.

[0030] The display unit 4 is composed of, for example, a liquid crystal display screen, is connected to the robot control device 3 by wire or wirelessly, and displays various information transmitted from the robot control device 3 on the screen.

[0031] Next, refer to Figure 3 The tension estimation device 32 and the life evaluation device 33 provided in the robot control device 3 are described below. Figure 3As shown, the tension estimating device 32 includes a motor heat generation calculating unit 321 , a friction heat generation calculating unit 322 , an air cooling heat dissipation calculating unit 323 , and a belt tension estimating unit 324 .

[0032] The motor heat generation calculation unit 321 calculates the motor heat generation based on the motor state quantity input from the control device 31. The motor heat generation calculation unit 321 can be input from the control device 31 with at least one of the motor current value and the motor rotation speed of at least one motor arranged close to the belt to be estimated. In this embodiment, Figure 3 As shown, the configuration is such that both the motor current value and the motor rotation speed value are input from the control device 31 .

[0033] Furthermore, a motor disposed close to a belt means a motor disposed so close to the belt that the heat generated by the motor's driving affects the belt's tension. Figure 2 In the case of the second arm 25 of the robot 2 shown, the J5-axis motor 5 and the J6-axis motor 7 are arranged near the belt 63. The tension of the belt 63 is affected by the heat generated by these J5-axis motor 5 and the J6-axis motor 7. Therefore, when estimating the tension of the belt 63 of the second arm 25, at least one of the motor current value and the motor rotation speed of the J5-axis motor 5 and the J6-axis motor 7 is input to the motor heat generation calculation unit 321.

[0034] The motor heat generation calculation unit 321 calculates the motor heat generation amount of the motor of the drive shaft as a calculation target using the following equation (1) based on at least one of the input motor current value and the motor rotation speed.

[0035] M n =a×C n +b×V n +c×(V n ) 2 ...(1)

[0036] M n :Motor heat generation of Jn-axis motor [W]

[0037] C n : Motor current value of Jn-axis motor [Ap]

[0038] V n : Motor rotation speed of Jn-axis motor [rpm]

[0039] a, b, c: coefficients

[0040] The frictional heat generation calculation unit 322 calculates the frictional heat generation in the transmission mechanism based on at least one of the motor current value, motor rotation speed, and friction coefficient of at least one shaft arranged close to the belt, which is the object of tension estimation, input from the control device 31. The motor current value and motor rotation speed input to the frictional heat generation calculation unit 322 are the motor current value and motor rotation speed of at least one motor arranged close to the belt, which is the object of tension estimation. For example, Figure 2 In the case of the second arm 25 of the robot 2 shown in FIG. 1 , the motor current values ​​and motor rotation speeds of the J5-axis motor 5 and the J6-axis motor 7 are shown. The axis is a part that generates frictional heat due to driving. For example, Figure 2 In the case of the second arm 25 of the robot 2 shown, frictional heat generated by driving the J4 axis 2 d , the J5 axis 2 e , and the J6 axis 2 f may affect the tension of the belt 63 .

[0041] like Figure 3 As shown, the frictional heat generation calculation unit 322 can input the motor current value, motor rotation speed, and at least one of the friction coefficients of the shafts described above from the control unit 31. The friction coefficient of the shaft is a value unique to each shaft and is stored in advance as a value for each shaft in a storage unit (not shown) of the control unit 31. The frictional heat generation calculation unit 322 calculates the frictional heat generation in the transmission mechanism based on at least one of the motor current value, motor rotation speed, and friction coefficient using the following equation (2).

[0042] F n =k1×C n V n +k2×V n +k3×(V n ) 2 ...(2)

[0043] F n : Frictional heat generated by the shaft driven by the Jn-axis motor [W]

[0044] C n : Motor current value of Jn-axis motor [Ap]

[0045] V n : Motor rotation speed of Jn-axis motor [rpm]

[0046] k: friction coefficient

[0047] The air cooling heat dissipation calculation unit 323 calculates the air cooling heat dissipation of the transmission mechanism based on the movement speed of the transmission mechanism. The air cooling heat dissipation is the heat dissipation generated by the arm moving in the air due to the movement of the robot 2, thereby generating a relative speed between the arm and the surrounding air. The air cooling heat dissipation is proportional to the movement speed ratio (V wcp) is proportional to the moving speed ratio of the transmission mechanism (V wcp ) is calculated by the following formula (3). In the robot 2, the speed of the arm is uniquely determined by the minute angular changes of the J1 axis 2a to the J6 axis 2f.

[0048] V wcp =(speed at a specific position of the arm) / (maximum speed at a specific position of the arm)…(3)

[0049] The belt tension estimating unit 324 calculates the belt tension in the transmission mechanism using the belt tension estimation formula shown in the following formula (4), based on the motor heat value calculated by the motor heat value calculating unit 321, the frictional heat value calculated by the frictional heat value calculating unit 322, and the air cooling heat value calculated by the air cooling heat value calculating unit 323. T0 and a, b, c, and d are coefficients specific to the model and unrelated to the motion of the robot 2.

[0050] [Number 1]

[0051]

[0052] T: estimated belt tension

[0053] T0: initial tension of the belt

[0054] F n : Frictional heat generated by the shaft driven by the Jn-axis motor [W]

[0055] M n :Motor heat generation of Jn-axis motor [W]

[0056] V wcp : The moving speed ratio of the transmission mechanism

[0057] m: any combination of integers

[0058] a, b, c, d: coefficients

[0059] For example, in robot 2, the tension of belt 63 of transmission mechanism 6 of second arm 25 is affected by the motor heat generated by J5-axis motor 5 and J6-axis motor 7, which are located close to belt 63, and the frictional heat generated by J4-axis 2d, J5-axis 2e, and J6-axis 2f, which are located close to belt 63. Therefore, in this case, in equation (4), the motor heat generated by J5-axis motor 5 and J6-axis motor 7 is used as the motor heat generated by motor 5 and J6-axis motor 7, and the frictional heat generated by J4-axis 2d, J5-axis 2e, and J6-axis 2f is used as the frictional heat generated by motor 5 and J6-axis motor 7, respectively.

[0060] Here, a description will be given of a case where the tension of the belt 63 of the transmission mechanism 6 in the second arm 25 is estimated when the robot 2 performs the following operation.

[0061] [Table 1]

[0062] J4 axis J5 axis J6 axis <![CDATA[Motor current value C n [Ap]]]> 10 12.5 7.5 <![CDATA[Motor rotation speed V n [rpm]]]> 1500 1500 1500

[0063] In the movement of the robot 2 as described above, the motor heat generation M5 of the J5-axis motor 5 driving the J5-axis 2e and the motor heat generation M6 of the J6-axis motor 7 driving the J6-axis 2f are: when a=0.5, b=0.005, c=0.000005, according to formula (1), M5=25[W], M6=22.5[W].

[0064] In the J4 axis 2d, the friction coefficient ka4 corresponding to the average value of the motor current speed is 0.005, and the friction coefficient k corresponding to the average motor rotation speed is 0.005. b4 The friction coefficient k is 0.10, corresponding to the root mean square of the motor rotation speed c4 When the friction coefficient k is 0.0001, according to formula (2), the friction heat F4 of the J4 axis 2d is 450 [W]. Similarly, in the J5 axis 2e, the friction coefficient k corresponding to the average value of the motor current speed is a5 The friction coefficient k is 0.0001, corresponding to the average rotation speed of the motor b5 The friction coefficient k is 0.02, corresponding to the root mean square of the motor rotation speed c5 When the frictional heat F5 of the J5 axis 2e is 0.00001, the frictional heat F5 is 54.4 [W]. In the J6 axis 2f, the friction coefficient k corresponding to the average value of the motor current speed is a6 The friction coefficient k is 0.001, corresponding to the average rotation speed of the motor b6 The friction coefficient k is 0.08, corresponding to the root mean square of the motor rotation speed c6 When it is 0.00001, the frictional heat generated by the J6 shaft 2f is F6 = 153.8 [W].

[0065] Substituting these values ​​into equation (4) yields the tension T of the belt 63. Furthermore, in equation (4), when T0 = 150 [N], m1 = 4.5.6, m2 = 5.6, m3 = 4.5.6, a4 = 0.1, a5 = 0, a6 = 1.2, b5 = 0.5, b6 = 0.5, c = 0.8, d = -0.5, V wcp =0.1, the tension of the belt 63 is estimated to be T = 200.8 [N]. Thus, the tension estimating device 32 can estimate the tension of the belt with high accuracy.

[0066] In the belt tension estimation formula of formula (4), the initial belt tension T0 and at least one of the coefficients a, b, c, and d are parameters that change according to the room temperature. By including the parameters that change according to the room temperature in the belt tension estimation formula, the belt tension can be estimated taking the room temperature into account. Therefore, the belt tension can be estimated with better accuracy. Figure 3 As shown, the room temperature can be inputted by a room temperature input unit 34 provided in the robot controller 3. The room temperature input unit 34 may input the room temperature manually by an operator or automatically input the detection value of a temperature sensor (not shown).

[0067] In the belt tension estimation formula of formula (4), the initial belt tension T0 and at least one of the coefficients a, b, c, and d may be parameters that change according to the time or operation time of the robot 2. This is because the belt tension may decrease as time passes. Figure 3 As shown, the operating time of the robot 2 is input from the control device 31 to the belt tension estimation unit 324. For example, when the belt tension decreases per hour [h] after the robot 2 operates as A [N / h], the estimated belt tension including the change over time can be calculated using the following formula (5).

[0068] T'=T0-At...(5)

[0069] T': estimated belt tension including time-varying variations [N]

[0070] T0: Initial tension of the belt [N]

[0071] A: Change over time per hour [N / h]

[0072] t: operating time [h]

[0073] Thus, the coefficients of the belt tension estimation formula (4) are corrected according to the elapsed time or operating time of the robot 2. Therefore, by including parameters that change according to the elapsed time or operating time of the robot 2 in the belt tension estimation formula, the belt tension can be estimated taking into account the elapsed time or operating time of the robot 2. Consequently, the belt tension can be estimated with greater accuracy.

[0074] Furthermore, the estimated belt tension based on the change over time can also be simply calculated using the following formula (6).

[0075] T'=f(t)×T...(6)

[0076] T': estimated belt tension including time-varying variations [N]

[0077] T: estimated belt tension [N]

[0078] f(t): coefficient depending on the running time

[0079] like Figure 3 As shown, the life evaluation device 33 includes the tension estimation device 32 described above, and further includes a life estimation unit 331 , a remaining life calculation unit 332 , and a replacement date calculation unit 333 .

[0080] The life estimating unit 331 estimates the life of the transmission mechanism based on the tension estimated value estimated by the belt tension estimating unit 324 of the tension estimating device 32. Figure 2 In the case of the transmission mechanism 6 of the second arm portion 25 shown, the life of the transmission mechanism 6 is estimated based on the estimated value of the tension of the belt 63 estimated by the tension estimating device 32 .

[0081] Generally speaking, the life of a transmission mechanism is considered to be proportional to the cube of the belt tension. The life estimation unit 331 estimates the life of the transmission mechanism using the following formula (7) based on the estimated belt tension value obtained by the tension estimation device 32. For example, in the case of a transmission mechanism whose life reaches 100% if it is operated for 10,000 hours when the belt tension is 250 [N], according to the following formula (7), the life progress rate (estimated life value) of the transmission mechanism when the estimated belt tension is 200 [N] and it has been operated for 5,000 hours is 26 [%]. Therefore, the life estimation unit 331 can estimate that the current life of the transmission mechanism has reached 26%.

[0082] [Number 2]

[0083]

[0084] S g : Estimated life of the transfer mechanism [%]

[0085] T: estimated belt tension [N]

[0086] t: operating time [h]

[0087] The remaining life calculation unit 332 calculates the remaining life of the transmission mechanism based on the estimated life value of the transmission mechanism calculated by the life estimation unit 331. As a result, the life evaluation device 33 can inform the operator of the remaining life of the transmission mechanism. Specifically, the remaining life calculation unit 332 calculates the remaining life S of the transmission mechanism based on the estimated life value of the transmission mechanism calculated by the life estimation unit 331 using the following formula (8): r .

[0088] S r =100-Sg [%]...(8)

[0089] S r : Remaining life [%]

[0090] S g : Estimated life of the transfer mechanism [%]

[0091] The remaining life information calculated by the remaining life calculation unit 332 is sent to the display unit 4 and displayed thereon. The display unit 4 can display the remaining life value sent from the remaining life calculation unit 332, or it can display a warning when the calculated remaining life value falls below a preset threshold. The function of determining whether the remaining life value has fallen below the threshold can be provided by either the remaining life calculation unit 332 or the display unit 4.

[0092] The replacement date calculation unit 333 calculates the estimated replacement date of the transmission mechanism based on the estimated life value of the transmission mechanism calculated by the life estimation unit 331. Based on this, the life evaluation device 33 can notify the operator of the approximate replacement date of the transmission mechanism before the transmission mechanism is damaged. In detail, the replacement date calculation unit 333 calculates the replacement date (recommended replacement date) of the transmission mechanism based on the estimated life value of the transmission mechanism calculated by the life estimation unit 331 using the following formula (9). The information on the replacement date calculated by the replacement date calculation unit 333 is sent to the display unit 4 and displayed on the display unit 4. However, the calculation method of the replacement date of the transmission mechanism is not limited to the following formula (9), and any other approximate calculation method may also be used.

[0093] [Number 3]

[0094]

[0095] D: Number of days until the replacement date [days]

[0096] S g (d) Estimated life span of the transmission mechanism d days ago [%]

[0097] S g (0): Estimated lifespan of the current transmission mechanism [%]

[0098] S g0 :Replacement limit of remaining life [%]

[0099] a: coefficient

[0100] As described above, the life evaluation device 33 can accurately evaluate the life of the transmission mechanism based on the estimated belt tension value obtained by the tension estimation device 32. Since the life evaluation device 33 evaluates the life of the transmission mechanism based on the belt tension obtained by the tension estimation device 32, it can accurately evaluate the life of the transmission mechanism while taking into account the load applied to the transmission mechanism due to the increase in belt tension.

[0101] The belt tension estimation unit 324 of the tension estimation device 32 can also generate a learned model for estimating belt tension based on the motor heat generation and frictional heat generation through machine learning using the motor heat generation calculated by the motor heat generation calculation unit 321 and the frictional heat generation calculated by the frictional heat generation calculation unit 322. This allows the belt tension to be accurately estimated using a learned model based on data on motor heat generation and frictional heat generation in various patterns.

[0102] When the belt tension estimation unit 324 generates a learned model, it may be as follows: Figure 4 As shown, the tension estimation device 32 includes a storage unit 325 that stores a learned model generated through machine learning. In this case, the belt tension estimation unit 324 can estimate the belt tension based on the motor heat generation and frictional heat generation using the learned model stored in the storage unit 325. Thus, by estimating the belt tension using the learned model stored in the storage unit 325, the belt tension can be estimated with greater accuracy, even without generating the learned model from the outset.

[0103] Machine learning can also be supervised learning using teacher data, which is data obtained by associating the motor heat and friction heat as input data and the measured value of the belt tension as a label. Based on this, the belt tension relative to the input data can be estimated with better accuracy by using the measured value of the belt tension as the correct answer. Figure 4 As shown, the actual measurement value of the belt tension can be inputted manually by an operator via the actual measurement value input unit 35 provided in the robot controller 3 .

[0104] In addition, if Figure 6 As shown in FIG, the belt tension and the temperature have a one-to-one relationship. Therefore, the belt tension estimation unit 324 of the tension estimation device 32 may estimate the belt tension based on the temperature of the transmission mechanism instead of using the above formula (4) to calculate the belt tension estimation value. Figure 5 As shown, the tension estimation device 32 in this case can include a transmission mechanism temperature estimation unit 326 .

[0105] The transmission mechanism temperature estimation unit 326 estimates the temperature of the transmission mechanism using the following formula (10) based on the motor heat value calculated by the motor heat value calculation unit 321, the friction heat value calculated by the friction heat value calculation unit 322, and the air cooling heat value calculated by the air cooling heat value calculation unit 323.

[0106] [Number 4]

[0107]

[0108] T p : Estimated temperature of the transfer mechanism

[0109] T r : Room temperature

[0110] F n : Frictional heat generated by the shaft driven by the Jn-axis motor [W]

[0111] M n :Motor heat generation of Jn-axis motor [W]

[0112] W1: air cooling heat dissipation

[0113] W2: Heat generated by other sources

[0114] a, b, c, d, e, f, g: coefficients

[0115] m: any combination of integers

[0116] The belt tension estimating unit 324 calculates the belt tension based on the temperature of the transmission mechanism estimated by the transmission mechanism temperature estimating unit 326. Figure 6 The belt tension can be estimated by the graph of the belt. Based on this, the belt tension can be easily estimated. Alternatively, the tension estimation device 32 having the transmission mechanism temperature estimation unit 326 can also be connected to the belt. Figure 4 The tension estimation device 32 shown similarly has a configuration for generating a learned model through machine learning.

[0117] In the above embodiments, the motor heat generation calculator 321 calculates the motor heat generation based on the motor current value and the motor rotation speed. However, the motor heat generation calculator 321 may calculate the motor heat generation more simply based on at least one of the motor current value and the motor rotation speed.

[0118] In each of the above embodiments, the frictional heat amount calculation unit 322 calculates the frictional heat amount in the transmission mechanism 6 based on the motor current value, the motor rotational speed, and the friction coefficient of the transmission mechanism 6. However, the frictional heat amount calculation unit 322 may simply calculate the frictional heat amount in the transmission mechanism 6 based on at least one of the motor current value, the motor rotational speed, and the friction coefficient of the transmission mechanism 6.

[0119] In each of the above embodiments, the tension estimation device 32 may be a simple device without the air cooling heat dissipation calculation unit 323. The belt tension estimation unit 324 may simply estimate the belt tension based on two heat amounts: motor heat and friction heat.

[0120] Description of Reference Numerals

[0121] 1: Robot system; 2: Robot (mechanical); 2a: J1 axis (movable part); 2b: J2 axis (movable part); 2c: J3 axis (movable part); 2d: J4 axis (movable part); 2e: J5 axis (movable part); 2f: J6 axis (movable part); 31: Control device; 32: Tension estimation device; 321: Motor heat generation calculation unit; 322: Friction heat generation calculation unit; 324: Belt tension estimation unit; 325: Storage unit; 326: Transmission mechanism temperature estimation unit; 33: Life evaluation device; 331: Life estimation unit; 332: Remaining life calculation unit; 333: Replacement day calculation unit; 5: J5-axis motor (first motor); 7: J6-axis motor (second motor); 6: Transmission mechanism; 63: Belt.

Claims

1. A tension estimation device comprising: a transmission mechanism that transmits power via a belt; at least one motor, the at least one motor being disposed proximate to the belt; a motor heat generation calculating unit for calculating the motor heat generation based on at least one of a current value and a rotational speed of the at least one motor; a frictional heat amount calculation unit that calculates the frictional heat amount of the transmission mechanism based on at least one of a current value and a rotational speed of the at least one motor and a friction coefficient of at least one shaft disposed proximate to the belt; a belt tension estimating unit that estimates the belt tension based on the motor heat amount and the frictional heat amount; and an air cooling heat dissipation calculation unit, which calculates the air cooling heat dissipation based on the moving speed of the transmission mechanism, The belt tension estimation unit estimates the belt tension based on the motor heat, the friction heat, and the air cooling heat using the following belt tension estimation formula: [Number 1] T: estimated belt tension T0: initial tension of the belt F n : Frictional heat generated by the shaft driven by the nth motor M n : Motor heat generation of the nth motor V wcp : The moving speed ratio of the transmission mechanism m: any combination of integers a, b, c, d: coefficients.

2. The tension estimation device according to claim 1, wherein: In the belt tension estimation formula, at least one of the initial belt tension and the coefficient is a parameter that changes depending on room temperature.

3. The tension estimation device according to claim 1, wherein In the belt tension estimation formula, at least one of the initial belt tension and the coefficient is a parameter that changes with elapsed time or operating time.

4. The tension estimation device according to claim 2, wherein: In the belt tension estimation formula, at least one of the initial belt tension and the coefficient is a parameter that changes with elapsed time or operating time.

5. The tension estimation device according to claim 1, wherein The device further comprises a transmission mechanism temperature estimation unit for estimating the temperature of the transmission mechanism based on the motor heat, the friction heat, and the air cooling heat dissipation. The belt tension estimating unit estimates the tension of the belt based on the temperature of the transmission mechanism estimated by the transmission mechanism temperature estimating unit.

6. The tension estimation device according to any one of claims 1 to 5, wherein: The transmission mechanism is composed of a member whose life varies in accordance with changes in the tension of the belt.

7. The tension estimation device according to any one of claims 1 to 5, wherein: The belt tension estimation unit generates a learned model for estimating the belt tension based on the motor heating amount and the frictional heating amount through machine learning using the motor heating amount and the frictional heating amount.

8. The tension estimating device according to claim 6, wherein: The belt tension estimation unit generates a learned model for estimating the belt tension based on the motor heating amount and the frictional heating amount through machine learning using the motor heating amount and the frictional heating amount.

9. The tension estimating device according to claim 7, wherein: further comprising a storage unit for storing the learned model generated by the machine learning, The belt tension estimation unit estimates the belt tension based on the motor heat amount and the frictional heat amount using the learned model stored in the storage unit.

10. The tension estimating device according to claim 8, wherein further comprising a storage unit for storing the learned model generated by the machine learning, The belt tension estimation unit estimates the belt tension based on the motor heat amount and the frictional heat amount using the learned model stored in the storage unit.

11. The tension estimating device according to claim 7, wherein: The machine learning is supervised learning using teacher data, wherein the teacher data is data obtained by associating the motor heat amount and the friction heat amount as input data and the measured value of the belt tension as a label.

12. The tension estimating device according to claim 8, wherein The machine learning is supervised learning using teacher data, wherein the teacher data is data obtained by associating the motor heat amount and the friction heat amount as input data and the measured value of the belt tension as a label.

13. The tension estimating device according to claim 9, wherein: The machine learning is supervised learning using teacher data, wherein the teacher data is data obtained by associating the motor heat amount and the friction heat amount as input data and the measured value of the belt tension as a label.

14. The tension estimating device according to claim 10, wherein: The machine learning is supervised learning using teacher data, wherein the teacher data is data obtained by associating the motor heat amount and the friction heat amount as input data and the measured value of the belt tension as a label.

15. A life evaluation device comprising: The tension estimating device according to any one of claims 1 to 14; and A life estimating unit estimates the life of the transmission mechanism based on the tension of the belt estimated by the tension estimating device.

16. The life evaluation device according to claim 15, wherein: The device further includes a remaining life calculation unit that calculates the remaining life of the transmission mechanism based on the life of the transmission mechanism estimated by the life estimation unit.

17. The life evaluation device according to claim 15, wherein: The device further includes a replacement date calculation unit that calculates an estimated replacement date of the transmission mechanism based on the life of the transmission mechanism estimated by the life estimation unit.

18. The life evaluation device according to claim 16, wherein: The device further includes a replacement date calculation unit that calculates an estimated replacement date of the transmission mechanism based on the life of the transmission mechanism estimated by the life estimation unit.

19. A robotic system comprising: A robot comprising a plurality of motors, a plurality of movable parts, and one or more transmission mechanisms for transmitting power of at least one of the plurality of motors to at least any one of the plurality of movable parts via a belt; a control device that controls the plurality of motors of the robot; and The life evaluation device according to any one of claims 15 to 18.

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