Workpiece mass estimation device

Abstract

The purpose of the present invention is to facilitate confirmation of whether or not repeated computations have been processed normally. This workpiece mass estimation device is a device for a machine. The machine includes a motor that drives a workpiece loading unit and a sensor that detects the state of the motor. The workpiece mass estimation device is provided with an identification unit, a storage unit, an estimation unit, and a display. The identification unit: identifies the value of a physical parameter of a driven body driven by output of the motor on the basis of the state of the motor detected by the sensor; and continues to update the identified value through repeated computation. The storage unit saves the value of the physical parameter being updated. The estimation unit estimates the mass of a workpiece on the basis of the final value of the physical parameter being updated. The display displays a graph indicating the course of the values of the physical parameter on the basis of data saved in the storage unit and displays the mass estimated by the estimation unit.

Description

Workpiece mass estimation device

[0001] The present disclosure relates to a workpiece mass estimation device that estimates the mass of a workpiece loaded on various machines such as machine tools.

[0002] Some machines, such as machine tools, are equipped with a workpiece loading section, a motor, a sensor, and a motor control section. A workpiece is loaded onto the workpiece loading section. The motor drives the workpiece loading section. The sensor detects the state of the motor. The state of the motor includes, for example, the current value and rotation speed of the motor. The motor control section performs feedback control of the motor based on the detected state of the motor.

[0003] JP 2015-55923 A

[0004] The total mass of the driven body driven by the motor varies depending on the mass of the workpieces loaded on the workpiece loading section. Therefore, the inertia of the driven body also varies depending on the mass of the workpieces. This change in inertia changes the acceleration / deceleration of the driven body caused by the motor. Excessive acceleration / deceleration places an excessive load on the machine, leading to machine failure, while insufficient acceleration / deceleration reduces the work efficiency of the machine. Therefore, it is necessary to adjust the acceleration / deceleration of the driven body caused by the motor to an optimal acceleration / deceleration. For this reason, some machines adjust the acceleration / deceleration of the driven body caused by the motor to an optimal acceleration / deceleration based on the workpiece mass input by the operator.

[0005] While this technology allows for the adjustment of the acceleration / deceleration of the driven body, it requires the operator to manually input the workpiece mass each time. Therefore, a method for automatically estimating the workpiece mass has been proposed, as follows: First, a predetermined operation command is sent to the machine's motor control unit, causing the motor to drive the driven body. The inertia of the driven body at this time is identified based on the current feedback value and rotational speed feedback value detected by the sensor. The inertia of the workpiece is calculated by subtracting the inertia caused by factors other than the workpiece from the identified inertia of the driven body, and the workpiece mass is then estimated.

[0006] However, the present inventors have noticed that such a configuration may cause the following problems.

[0007] In the process of estimating the mass of the workpiece, the values ​​of physical parameters may be successively updated by repeated calculations such as the steepest descent method. The physical parameters include the inertia of the driven body and parameters for calculating the inertia. The estimated mass of the workpiece is calculated based on the final value of the updated physical parameters. Therefore, the estimated mass of the workpiece depends on the final value.

[0008] If the repeated calculations are processed normally, there is no particular problem. However, if the repeated calculations are not processed normally, the values ​​of the physical parameters do not converge within the time limit, and the final values ​​do not become correct. As a result, a discrepancy occurs between the estimated workpiece mass and the actual workpiece mass.

[0009] The present disclosure has been made in consideration of the above circumstances, and aims to make it easier to check whether repeated operations are being processed normally.

[0010] The workpiece mass estimation device disclosed herein is a workpiece mass estimation device that estimates the mass of a workpiece for a machine having a workpiece loading section on which a workpiece is loaded, a motor that drives the workpiece loading section, a sensor that detects the state of the motor, and a motor control section that controls the motor based on the detected state of the motor, and includes an identification section that identifies the value of a physical parameter of a driven body driven by the output of the motor from the detected state of the motor and updates the identified value through repeated calculations; a memory section that saves the values ​​of the physical parameter as they are updated; an estimation section that estimates the mass of the workpiece from the final value of the physical parameter as it is updated; and a display that displays a graph showing the progress of the value of the physical parameter based on data saved in the memory section and displays the mass estimated by the estimation section.

[0011] Fig. 1 is a schematic diagram showing a workpiece mass estimation device and a machine tool of a first embodiment; Fig. 2 is a flowchart showing a flow of workpiece mass estimation; Fig. 3 is a diagram showing a normal pattern displayed on a display; Fig. 4 is a diagram showing a first abnormal pattern displayed on a display; Fig. 5 is a diagram showing a second abnormal pattern displayed on a display; Fig. 6 is a diagram showing a third abnormal pattern displayed on a display; and Fig. 7 is a diagram showing a fourth abnormal pattern displayed on a display.

[0012] 1, a workpiece mass estimation device 100 of this embodiment is installed on a machine tool 200. The machine tool 200 includes a motor control unit 50, a sensor 60, a motor 70, a transmission mechanism 80, and a workpiece loading unit 90.

[0013] The workpiece loading section 90 is provided so as to be movable in a rotational direction or a linear direction. A workpiece W is loaded on the workpiece loading section 90. The motor 70 has a rotor 78 and a stator 76 that rotates the rotor 78. Hereinafter, the output from the stator 76 to the rotor 78 will be referred to as the "motor output Mo." The transmission mechanism 80 transmits the motor output Mo from the rotor 78 to the workpiece loading section 90. The transmission mechanism 80 may include a reducer such as a gear.

[0014] Hereinafter, the portion of machine tool 200 that transmits motor output Mo to workpiece loading unit 90 will be referred to as the "transmission system." The transmission system includes transmission mechanism 80 and its periphery. Hereinafter, the group of parts driven by motor output Mo will be referred to as the "driven body Dv." The driven body Dv includes rotor 78, transmission mechanism 80, workpiece loading unit 90, and workpiece W. Hereinafter, the driven body Dv excluding workpiece W will be referred to as the "general driven body."

[0015] The sensor 60 detects motor information Mi indicating the state of the motor 70. The motor information Mi includes the current value of the motor 70 and the rotation speed of the rotor 78. The motor control unit 50 performs feedback control of the motor 70 based on the motor information Mi detected by the sensor 60.

[0016] Next, we will explain the workpiece mass estimation device 100. The workpiece mass estimation device 100 is a device for estimating the mass of the workpiece W. Hereinafter, estimation of the mass of the workpiece W will be simply referred to as "mass estimation," and the mass estimated by this mass estimation will be simply referred to as "estimated mass."

[0017] The workpiece mass estimation device 100 comprises an identification unit 10, a storage unit 20, an estimation unit 30, and a display 40. The identification unit 10, the storage unit 20, and the estimation unit 30 are, for example, configured mainly by the same computer. The display 40 is, for example, configured mainly by the above-mentioned computer and display. The computer has, for example, a CPU, ROM, RAM, memory, etc. Note that while the workpiece mass estimation device 100 and the machine tool 200 are shown as separate entities in FIG. 1, the workpiece mass estimation device 100 may also be incorporated within the machine tool 200.

[0018] The identification unit 10 identifies physical parameters of the driven body Dv from the motor information Mi detected by the sensor 60 and sequentially updates the identified values ​​through repeated calculations such as the steepest descent method. The physical parameters include the inertia of the driven body Dv, the viscous friction coefficient in the transmission system, the Coulomb friction coefficient in the transmission system, and the spring constant in the transmission system. Hereinafter, the viscous friction coefficient in the transmission system will be simply referred to as the "viscous friction coefficient," the Coulomb friction coefficient in the transmission system will be simply referred to as the "Coulomb friction," and the spring constant in the transmission system will be simply referred to as the "spring constant." The inertia of the driven body Dv is calculated taking into account the viscous friction coefficient, the Coulomb friction coefficient, and the spring constant.

[0019] The storage unit 20 stores the values ​​of the physical parameters that are updated by the identification unit 10 .

[0020] When the final value of the physical parameter being updated by the identification unit 10 is within a predetermined range, the estimation unit 30 estimates the mass from the final value. Specifically, the estimation unit 30 calculates the inertia of the workpiece W by subtracting the inertia of the general driven body from the final value of the inertia of the driven body Dv identified by the identification unit 10. The inertia of the general driven body is calculated, for example, based on the mass of the general driven body that has been input in advance. The estimation unit 30 estimates the mass from the calculated inertia of the workpiece W. On the other hand, when the final value of the physical parameter being updated by the identification unit 10 is outside the predetermined range, the estimation unit 30 does not estimate the mass.

[0021] 3 to 7, the display device 40 displays a graph 41 showing the transition of the values ​​of the physical parameters based on the data stored in the storage unit 20. The graph 41 includes an inertia graph 41a showing the transition of the inertia, a viscous friction coefficient graph 41b showing the transition of the viscous friction coefficient, a Coulomb friction coefficient graph 42c showing the transition of the Coulomb friction coefficient, and a spring constant graph 42d showing the transition of the spring constant.

[0022] When mass estimation is performed by the estimation unit 30, the display 40 displays mass information 42 indicating the estimated mass while displaying a graph 41, as shown in Fig. 3. On the other hand, when mass estimation is not performed, that is, when the final value of the physical parameter is outside the predetermined range, the display 40 displays an alarm 42A such as "ERR" instead of displaying the mass information 42, as shown in Figs. 4 to 7. In other words, the display 40 displays the alarm 42A while displaying the graph 41.

[0023] As shown in FIGS. 3 to 7, the display 40 displays a graph 41, a switching section 43, an operation pattern selection section 44, a drive amount selection section 45, status information 46, date and time information 47, and temperature information 48.

[0024] The switching unit 43 is a section for switching between execution and pause of mass estimation. The switching unit 43 also serves as a reset unit for initializing the estimated mass. The switching unit 43 is configured so that the operator can select either "SET" or "RESET." When "SET" is selected, execution of mass estimation is selected. On the other hand, when "RESET" is selected, execution of mass estimation is paused and the estimated mass is initialized. Note that when "SET" is selected and an error occurs, such as the final value of a physical parameter being outside a predetermined range, the selection automatically returns to "RESET," as shown in FIGS. 4 to 7.

[0025] The operation pattern selection unit 44 is a unit for selecting the operation conditions of the driven body Dv in the mass estimation. The drive amount selection unit 45 is a unit for selecting the drive amount of the driven body Dv in the mass estimation.

[0026] The status information 46 indicates whether the mass estimation was completed normally. That is, if the mass estimation was completed normally, the status information 46 displays a message indicating that the mass estimation was completed, such as "Adjustment completed," as shown in Fig. 3. On the other hand, if the mass estimation was not completed normally, the status information 46 displays a message indicating that the mass estimation was not completed, such as "Adjustment failed," as shown in Figs. 4 to 7.

[0027] The date and time information 47 indicates the date and time (year, month, day, time, etc.) when the mass estimation was completed. The temperature information 48 indicates the real-time temperature of a predetermined part of the motor 70. The predetermined part is a part of the motor 70 whose temperature affects the mass estimation.

[0028] Next, the flow of mass estimation by the workpiece mass estimation device 100 will be described with reference to FIG. 2. Note that "S" below stands for "step." First, in S1, it is determined whether mass estimation is currently being performed. If a negative determination N (No) is made, the determination in S1 is repeated. On the other hand, if a positive determination Y (Yes) is made in S1, the process proceeds to the next S2.

[0029] In S2, the identification unit 10 acquires the motor information Mi from the motor control unit 50.

[0030] In the next step S3, the identification unit 10 identifies the value of the physical parameter based on the motor information Mi. In the next step S4, the storage unit 20 stores the identified parameter information. Next, in step S5, it is determined whether the duration of the estimation process has reached the time limit. If a negative determination is made, the process returns to step S3. This allows the identification unit 10 to continue the repeated calculations. On the other hand, if a positive determination is made in step S5, the process proceeds to step S6.

[0031] In S6, it is determined whether the final values ​​of the identified physical parameters are within a predetermined range. If a positive determination is made, the process proceeds to S8. In S8, the estimation unit 30 estimates the mass of the workpiece W based on the final values ​​of the identified physical parameters. In the following S9, the display 40 displays a graph 41 based on the data stored in the memory unit 20, while also displaying the estimated mass estimated by the estimation unit 30 as mass information 42.

[0032] On the other hand, if a negative determination N is made in S6, that is, if the final value of the identified physical parameter is not within the predetermined range, the process proceeds to S9, in which the display 40 displays a graph 41 based on the data stored in the storage unit 20, and also displays an alarm 42A.

[0033] Next, the display patterns displayed on the display 40 will be described with reference to FIGS.

[0034] 3 shows a normal pattern Np obtained when the repeated calculations are performed normally. In this normal pattern Np, all physical parameters converge. Therefore, the values ​​of the physical parameters converge in the inertia graph 41 a, the viscous friction coefficient graph 41 b, the Coulomb friction coefficient graph 41 c, and the spring constant graph 41 d.

[0035] 4, the repeated calculations are not performed correctly for all physical parameters, resulting in divergent values ​​in the inertia graph 411, the viscous friction coefficient graph 412, the Coulomb friction coefficient graph 413, and the spring constant graph 414.

[0036] In the second abnormal pattern Ap2 shown in FIG. 5, a wavy waveform appears on the inertia graph 411 due to unstable fixation of the workpiece W or the presence of an unsteady disturbance.

[0037] In the third abnormal pattern Ap3 shown in FIG. 6, a protruding waveform appears in the Coulomb friction coefficient graph 41c due to wear and deterioration of sliding parts in the transmission system.

[0038] 7, the spring constant changes due to a change from elastic deformation to plastic deformation in components of the transmission system, etc. As a result, irregularly diverging waveforms appear on the spring constant graph 41d.

[0039] From the above, the operator can determine whether the repeated calculations have been processed normally based on graph 41. Furthermore, if the repeated calculations have not been processed normally, the cause can be determined based on the waveform appearing in graph 41. In other words, the operator can infer the cause of the failure in mass estimation by determining which of the shapes in Figures 4 to 7 the behavior appearing in graph 41 resembles.

[0040] The configuration and effects of this embodiment will be summarized below.

[0041] The display 40 displays the graph 41 and the mass information 42. Therefore, the operator can check whether the repeated calculations are being processed normally based on the graph 41, and can also check the estimated mass based on the mass information 42. Furthermore, if the repeated calculations are not being processed normally, the cause can be determined based on the waveform that appears on the graph 41. This makes it easier for the operator to perform the next appropriate processing.

[0042] Specifically, graph 41 includes an inertia graph 41a, a viscous friction coefficient graph 41b, a Coulomb friction coefficient graph 41c, and a spring constant graph 41d. If the repeated calculations are not processed normally, the behaviors shown in Figures 4 to 7 will appear in these graphs 41a to 41d. Therefore, the operator can infer the cause of the failure in mass estimation by determining which shape these behaviors resemble.

[0043] The display 40 displays the graph 41 and the switching unit 43. Therefore, the operator can use the switching unit 43 to switch between executing and pausing mass estimation while checking the trend of the repeated calculations based on the graph 41.

[0044] The display 40 displays date and time information 47 while displaying the graph 41. Therefore, if the repeated calculations are not processed normally, the operator can check the date and time when the mass estimation was completed based on the date and time information 47, and can also check the cause of the failure of the mass estimation based on the graph 41.

[0045] The display 40 displays the temperature information 48 in real time while displaying the graph 41. Therefore, if the repeated calculations are not processed normally, the operator can check the temperature of the motor 70 based on the temperature information 48 and also check the cause of the failure in the mass estimation based on the graph 41.

[0046] The display 40 displays the graph 41 and the operation pattern selection unit 44. Therefore, if the repeated calculations are not processed normally, the operator can change the operation conditions of the driven body Dv using the operation pattern selection unit 44 while checking the cause of the failure in the mass estimation based on the graph 41.

[0047] The display 40 displays the drive amount selection unit 45 while displaying the graph 41. Therefore, if the repeated calculations are not processed normally, the operator can change the drive amount of the driven body Dv using the drive amount selection unit 45 while checking the cause of the failure in the mass estimation based on the graph 41.

[0048] If mass estimation is not completed successfully, display 40 displays graph 41 and also displays a message indicating that mass estimation is incomplete as status information 46. Therefore, the operator can quickly recognize that mass estimation is incomplete based on status information 46, and can also confirm the cause of the failure of mass estimation based on graph 41.

[0049] The switching unit 43 also functions as a reset unit for initializing the estimated mass. That is, the display displays the reset unit while displaying the graph 41. Therefore, the operator can check the trend of the repeated calculations based on the graph 41, and reset the estimated mass using the reset unit as needed.

[0050] When the identified physical parameter falls outside a predetermined range, the display 40 displays an alarm 42A while displaying the graph 41. Therefore, the operator can quickly recognize the failure of the mass estimation based on the alarm 42A, and can also confirm the cause of the failure based on the graph 41.

[0051] Other Embodiments The above-described embodiments can be modified, for example, as follows. The workpiece mass estimation device 100 may be installed on a machine other than the machine tool 200. With respect to the graph 41, some of the four graphs 41a to 41d described above may be omitted, or additional graphs may be added. The inertia graph 41a may show the transition in the inertia of the workpiece W instead of the transition in the inertia of the driven body Db. With respect to the information 42A, 43 to 48 displayed together with the graph 41 other than the mass information 42, some may be omitted, or additional information may be added. The switching unit 43, operation pattern selection unit 44, drive amount selection unit 45, etc. may be displayed in a manner other than as shown in FIGS. 3 to 7.

[0052] According to the above embodiment, the workpiece mass estimation device (100) described in Supplementary Notes 1 to 9 below can be realized.

[0053] [Supplementary Note 1] A workpiece mass estimation device (100) for estimating the mass of a workpiece (W) for a machine (200) having a workpiece loading section (90) on which a workpiece (W) is loaded, a motor (70) for driving the workpiece loading section (90), a sensor (60) for detecting the state of the motor (70), and a motor (70) controller for controlling the motor (70) based on the detected state of the motor (70), comprising: an identification section (10) for identifying values ​​of physical parameters of a driven body (Dv) driven by the output of the motor (70) from the detected state of the motor (70) and updating the identified values ​​by repeated calculation; a storage section (20) for saving the values ​​of the physical parameters as they are updated; and an estimation section (30) for estimating the mass of the workpiece (W) from the final values ​​of the physical parameters as they are updated. a display (40) that displays a graph (41) showing a transition of the value of the physical parameter based on the data stored in the memory unit (20), and also displays the mass (42) estimated by the estimation unit (30).

[0054] [Supplementary Note 2] The workpiece mass estimation device (100) according to Supplementary Note 1, wherein the display (40) displays the graph (41) and a switching unit (43) for switching between execution and pause of the mass estimation.

[0055] [Supplementary Note 3] The workpiece mass estimation device (100) according to Supplementary Note 1 or 2, wherein the display (40) displays the graph (41) and also displays a date and time (47) when the estimation of the mass is completed.

[0056] [Supplementary Note 4] The workpiece mass estimation device (100) according to any one of Supplementary Notes 1 to 3, wherein the display (40) displays the temperature (48) of the motor (70) in real time while displaying the graph (41).

[0057] [Appendix 5] The workpiece mass estimation device (100) according to any one of Appendices 1 to 4, wherein the display (40) displays the graph (41) while also displaying an operation pattern selection unit (44) for selecting an operation condition for the driven body (Dv).

[0058] [Appendix 6] The workpiece mass estimation device (100) according to any one of Appendices 1 to 5, wherein the display (40) displays the graph (41) and, if estimation of the mass of the workpiece (W) is not completed successfully, displays a message (46) indicating that estimation of the mass is incomplete.

[0059] [Appendix 7] The workpiece mass estimation device (100) according to any one of Appendices 1 to 6, wherein the display (40) displays the graph (41) and also displays a reset unit (43) for initializing the estimated mass.

[0060] [Appendix 8] The workpiece mass estimation device (100) according to any one of Appendices 1 to 7, wherein the display (40) displays an alarm (42A) while displaying the graph (41) when the identified physical parameter falls outside a predetermined range.

[0061] [Appendix 9] The workpiece mass estimation device (100) according to any one of Appendices 1 to 8, wherein the graph (41) includes: an inertia graph (41a) showing a change in the inertia of the driven body (Dv); a viscous friction coefficient graph (4b1) showing a change in the viscous friction coefficient in a transmission system that transmits the output of the motor (70) to the workpiece loading section (90); a Coulomb friction coefficient graph (41c) showing a change in the Coulomb friction coefficient in the transmission system; and a spring constant graph (41d) showing a change in the spring constant in the transmission system.

[0062] According to the workpiece mass estimation device (100) of Supplementary Notes 1 to 9 above, it is possible to easily check whether the repeated calculations are being processed normally.

[0063] Although the present disclosure has been described in detail above, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0064] REFERENCE SIGNS LIST 10 Identification unit 20 Memory unit 30 Estimation unit 40 Display 41 Graph 41a Inertia graph 41b Viscous friction coefficient graph 41c Coulomb friction coefficient graph 41d Spring constant graph 42 Mass 42A Alarm 43 Switching unit 44 Operation pattern selection unit 46 Status information 47 Date and time information 48 Temperature information 50 Motor control unit 60 Sensor 70 Motor 90 Workpiece loading unit 100 Workpiece mass estimation device 200 Machine tool (machine) W Workpiece

Claims

1. A machine having a workpiece loading section on which a workpiece is loaded, a motor that drives the workpiece loading section, a sensor that detects the state of the motor, and a motor control section that controls the motor based on the detected state of the motor. A workpiece mass estimation device that estimates the mass of the workpiece, an identification unit that identifies a value of a physical parameter of a driven body driven by the output of the motor from the detected state of the motor, and updates the identified value by repeated calculation; a storage unit for storing the updated values ​​of the physical parameters; an estimation unit that estimates the mass of the workpiece from the final value of the updated physical parameter; a display that displays a graph showing a transition of the value of the physical parameter based on the data stored in the storage unit, and also displays the mass estimated by the estimation unit; A workpiece mass estimation device comprising:

2. 2. The workpiece mass estimation device according to claim 1, wherein the display device displays a switching unit for switching between execution and pause of the mass estimation while displaying the graph.

3. The workpiece mass estimation device according to claim 1 or 2, wherein the display device displays the graph and also displays a date and time when the estimation of the mass is completed.

4. The workpiece mass estimation device according to claim 1 or 2, wherein the display device displays the temperature of the motor in real time while displaying the graph.

5. 3. The workpiece mass estimation device according to claim 1, wherein the display device displays an operation pattern selection section for selecting an operation condition of the driven body while displaying the graph.

6. 3. The workpiece mass estimation device according to claim 1, wherein the display displays the graph and, if estimation of the workpiece mass is not completed successfully, displays a message indicating that estimation of the mass is incomplete.

7. The workpiece mass estimation device according to claim 1 or 2, wherein the display displays a reset section for initializing the estimated mass while displaying the graph.

8. 3. The workpiece mass estimation device according to claim 1, wherein the display displays an alarm while displaying the graph when the identified physical parameter falls outside a predetermined range.

9. The graph is an inertia graph showing a transition of the inertia of the driven body; a viscous friction coefficient graph showing a transition of a viscous friction coefficient in a transmission system that transmits the output of the motor to the workpiece loading unit; a Coulomb friction coefficient graph showing a change in the Coulomb friction coefficient in the transmission system; A spring constant graph showing a change in the spring constant in the transmission system. The workpiece mass estimation device according to claim 1 or 2.