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

Technical Field

[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.

Background Art

[0002] Some machines such as machine tools include a workpiece loading section, a motor, a sensor, and a motor control section. A workpiece is loaded on 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 rotational speed of the motor. The motor control section performs feedback control of the motor based on the detected state of the motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The total mass of the driven body driven by the motor changes depending on the mass of the workpiece loaded on the workpiece loading section. Therefore, the inertia of the driven body also changes depending on the mass of the workpiece. Due to the change in the inertia, the acceleration and deceleration of the driven body by the motor change. Excessive acceleration and deceleration impose an excessive load on the machine and may lead to a machine failure. On the other hand, insufficient acceleration and deceleration deteriorate the working efficiency of the machine. Therefore, it is necessary to adjust the acceleration and deceleration of the driven body by the motor to an optimal acceleration and deceleration. Therefore, some machines adjust the acceleration and deceleration of the driven body by the motor to an optimal acceleration and deceleration based on the mass of the workpiece input by the operator.

[0005] While such technology allows for adjustment of the acceleration and deceleration of the driven object, 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 motor control unit of the machine to drive the driven object using the motor. The inertia of the driven object at this time is identified based on current feedback values ​​and rotational speed feedback values ​​detected by sensors. 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 object, thereby estimating the workpiece mass.

[0006] However, the Disclosing Parties noted that such a configuration could lead to the following problems.

[0007] In the process of estimating the mass of a workpiece, iterative calculations such as the steepest descent method may be used to sequentially update the values ​​of physical parameters. These physical parameters include the inertia of the driven object and the parameters used to calculate it. The estimated mass of the workpiece is calculated based on the final value of these updated physical parameters. Therefore, the estimated mass of the workpiece depends on this final value.

[0008] If the iterative calculation is processed correctly, there are no particular problems. However, if the iterative calculation is not processed correctly, the values ​​of the physical parameters will not converge within the time limit, and the final values ​​will not be correct. As a result, a discrepancy will occur between the estimated mass of the workpiece and the actual mass of the workpiece.

[0009] This disclosure is made in view of the above circumstances and aims to make it easier to verify whether or not iterative calculations are being processed correctly. [Means for solving the problem]

[0010] The workpiece mass estimation apparatus disclosed herein is A machine having a workpiece loading section on which workpieces are loaded, a motor that drives the workpiece loading section, a sensor that detects the state of the motor, and a motor control unit that controls the motor based on the detected state of the motor, A workpiece mass estimation device for estimating the mass of the aforementioned workpiece, An identification unit identifies the values ​​of the physical parameters of the driven object driven by the motor's output based on the detected state of the motor, and updates the identified values ​​through iterative calculations. A memory unit that stores the updated values ​​of the aforementioned physical parameters, An estimation unit that estimates the mass of the workpiece from the final value of the updated physical parameter, A display unit that displays a graph showing the changes in the values ​​of the physical parameters based on the data stored in the memory unit, and also displays the mass estimated by the estimation unit, It is equipped with. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing a workpiece mass estimation device and a machine tool according to the first embodiment. [Figure 2] This is a flowchart showing the workflow for estimating the mass of a workpiece. [Figure 3] This diagram shows the normal pattern displayed on the indicator. [Figure 4] This figure shows the first abnormal pattern displayed on the indicator. [Figure 5] This figure shows the second abnormal pattern displayed on the indicator. [Figure 6] This figure shows the third abnormal pattern displayed on the indicator. [Figure 7] This figure shows the fourth abnormal pattern displayed on the indicator. [Modes for carrying out the invention]

[0012] [First Embodiment] As shown in FIG. 1, the workpiece mass estimation device 100 of the present embodiment is installed on the 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 unit 90 is provided so as to be movable in the rotational direction or the linear direction. A workpiece W is loaded on the workpiece loading unit 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 is referred to as "motor output Mo". The transmission mechanism 80 transmits the motor output Mo from the rotor 78 to the workpiece loading unit 90. The transmission mechanism 80 may include a speed reducer such as a gear.

[0014] Hereinafter, the part that transmits the motor output Mo to the workpiece loading unit 90 in the machine tool 200 is referred to as the "transmission system". The transmission system includes the transmission mechanism 80 and its periphery. Also hereinafter, the group of components driven by the motor output Mo is referred to as the "driven body Dv". The driven body Dv includes the rotor 78, the transmission mechanism 80, the workpiece loading unit 90, and the workpiece W. Also hereinafter, the one excluding the workpiece W from the driven body Dv is 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 rotational 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, the workpiece mass estimation device 100 will be described. The workpiece mass estimation device 100 is a device for estimating the mass of the workpiece W. Hereinafter, the estimation of the mass of the workpiece W is simply referred to as "mass estimation", and the mass estimated by the mass estimation is simply referred to as the "estimated mass".

[0017] The workpiece mass estimation device 100 includes 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 aforementioned computer and a display. The computer has, for example, a CPU, a ROM, a RAM, a memory, and the like. In FIG. 1, the workpiece mass estimation device 100 and the machine tool 200 are shown separately from each other, but the workpiece mass estimation device 100 may be incorporated in the machine tool 200.

[0018] The identification unit 10 identifies the physical parameters of the driven body Dv from the motor information Mi detected by the sensor 60, and sequentially updates the identified values by iterative 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 in consideration of the viscous friction coefficient, the Coulomb friction coefficient, and the spring constant.

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

[0020] When the final value of the physical parameter values updated by the identification unit 10 is within a predetermined range, the estimation unit 30 performs mass estimation 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 input in advance. The estimation unit 30 performs mass estimation from the calculated inertia of the workpiece W. On the other hand, when the final value of the physical parameter values updated by the identification unit 10 is out of the predetermined range, the estimation unit 30 does not perform mass estimation.

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

[0022] If the estimation unit 30 performs mass estimation, the display unit 40 displays the graph 41 and mass information 42 indicating the estimated mass, as shown in Figure 3. On the other hand, if mass estimation is not performed, that is, if the final value of the physical parameters falls outside a predetermined range, the display unit 40 does not display the mass information 42, as shown in Figures 4 to 7, but instead displays an alarm 42A such as "ERR". In other words, the display unit 40 displays the graph 41 and the alarm 42A.

[0023] As shown in Figures 3 to 7, the display unit 40 displays the graph 41 while also displaying the switching unit 43, the operation pattern selection unit 44, the drive amount selection unit 45, the status information 46, the date and time information 47, and the temperature information 48.

[0024] The switching unit 43 is the part for switching between running and pausing mass estimation. The switching unit 43 also serves as a reset unit for initializing the estimated mass. The switching unit 43 is configured to allow the operator to select either "SET" or "RESET". When "SET" is selected, the execution of mass estimation is selected. On the other hand, when "RESET" is selected, the execution of mass estimation is paused and the estimated mass is initialized. If an error occurs when "SET" is selected, such as the final value of the physical parameters falling outside a predetermined range, the selection will automatically return to "RESET" as shown in Figures 4 to 7.

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

[0026] Status information 46 indicates whether the mass estimation was completed successfully. In other words, if the mass estimation was completed successfully, status information 46 will display "Adjustment Complete" or similar, as shown in Figure 3. On the other hand, if the mass estimation was not completed successfully, status information 46 will display "Adjustment Failed" or similar, as shown in Figures 4 to 7, as indicated by the status information 46.

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

[0028] Next, referring to Figure 2, the flow of mass estimation by the workpiece mass estimation device 100 will be explained. In the following, "S" stands for "step". First, in S1, it is determined whether or not mass estimation is in progress. If a negative determination N (No) is made, the determination in S1 is repeated. On the other hand, if an affirmative determination Y (Yes) is made in S1, the process proceeds to the next S2.

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

[0030] In the following step S3, the identification unit 10 identifies the values ​​of the physical parameters based on the motor information Mi. In the following 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 N is made, the process returns to S3. This allows the iterative calculation by the identification unit 10 to continue. On the other hand, if an affirmative determination Y is made in S5, the process proceeds to the next 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 Y 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 subsequent S9, the display unit 40 displays a graph 41 based on the data stored in the memory unit 20, and displays the estimated mass estimated by the estimation unit 30 as mass information 42.

[0032] On the other hand, if a negative judgment N is made in step S6, that is, if the final value of the identified physical parameter is not within a predetermined range, the process proceeds to S9. In S9, the display unit 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 shown on the display unit 40 will be explained with reference to Figures 3 to 7.

[0034] The normal pattern Np shown in Figure 3 represents the case where the iterative calculation is processed correctly. In this normal pattern Np, all physical parameters converge. Therefore, the convergence of the physical parameter values ​​is observed in each of the inertia graph 41a, viscous friction coefficient graph 41b, Coulomb friction coefficient graph 41c, and spring constant graph 41d.

[0035] In the first abnormal pattern Ap1 shown in Figure 4, the iterative calculations are not processed correctly for all physical parameters. As a result, the inertia graph 411, the viscous friction coefficient graph 412, the Coulomb friction coefficient graph 413, and the spring constant graph 414 all exhibit divergent behavior.

[0036] In the second abnormal pattern Ap2 shown in Figure 5, a wavy waveform appears on the inertia graph 411 due to unstable fixing of the workpiece W or the presence of non-stationary disturbances.

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

[0038] In the fourth abnormal pattern Ap4 shown in Figure 7, the spring constant changes due to a shift from elastic deformation to plastic deformation in components of the transmission system. As a result, irregularly diverging waveforms appear in the spring constant graph 41d.

[0039] Based on the above, the operator can determine whether the iterative calculation was processed correctly or not based on Graph 41. Furthermore, if the iterative calculation was not processed correctly, the cause can be determined based on the waveform appearing in Graph 41. In other words, the operator can infer the cause of the mass estimation failure 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 are summarized below.

[0041] The display unit 40 displays both graph 41 and mass information 42. Therefore, the operator can verify whether the iterative calculation is being processed correctly based on graph 41, and also verify the estimated mass based on mass information 42. Furthermore, if the iterative calculation is not processed correctly, the cause can be determined based on the waveform appearing in graph 41. This makes it easier for the operator to perform the next appropriate action.

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

[0043] The display unit 40 displays the graph 41 while also displaying the switching unit 43. Therefore, the operator can check the trends of the iterative calculations based on the graph 41 and switch between running and pausing the mass estimation using the switching unit 43.

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

[0045] The display unit 40 displays temperature information 48 in real time while displaying graph 41. Therefore, if the iterative calculation is not processed correctly, the operator can check the temperature of the motor 70 based on the temperature information 48 and check the cause of the mass estimation failure based on graph 41.

[0046] The display unit 40 displays the graph 41 while also displaying the operation pattern selection unit 44. Therefore, if the iterative calculation is not processed correctly, the operator can check the cause of the mass estimation failure based on the graph 41 and change the operating conditions of the driven body Dv using the operation pattern selection unit 44.

[0047] The display unit 40 displays the drive amount selection unit 45 while displaying the graph 41. Therefore, if the iterative calculation is not processed correctly, the operator can check the cause of the mass estimation failure based on the graph 41 and change the drive amount of the driven body Dv using the drive amount selection unit 45.

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

[0049] The switching unit 43 also functions as a reset unit for initializing the estimated mass. In other words, the display shows the reset unit while displaying the graph 41. Therefore, the operator can check the trends of the iterative calculations based on the graph 41 and reset the estimated mass using the reset unit as needed.

[0050] The display unit 40 displays an alarm 42A while showing graph 41 when the identified physical parameters fall outside a predetermined range. Therefore, the operator can quickly recognize a failure in mass estimation based on alarm 42A and confirm the cause of the failure based on graph 41.

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

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

[0053] [Note 1] A machine (200) having a workpiece loading section (90) on which workpieces (W) are loaded, a motor (70) that drives the workpiece loading section (90), a sensor (60) that detects the state of the motor (70), and a motor (70) controller that controls the motor (70) based on the detected state of the motor (70), A workpiece mass estimation device (100) for estimating the mass of the workpiece (W), An identification unit (10) identifies the values ​​of the physical parameters of the driven body (Dv) driven by the output of the motor (70) based on the detected state of the motor (70), and updates the identified values ​​through iterative calculations. A storage unit (20) that stores the updated values ​​of the aforementioned physical parameters, An estimation unit (30) estimates the mass of the workpiece (W) from the final value of the updated physical parameter, A display unit (40) that displays a graph (41) showing the changes in the values ​​of the physical parameters based on the data stored in the memory unit (20), and also displays the mass (42) estimated by the estimation unit (30), A workpiece mass estimation device (100) equipped with the following.

[0054] [Note 2] The display unit (40) displays the graph (41) and a switching unit (43) for switching between performing and pausing the mass estimation, as described in Appendix 1, for the workpiece mass estimation device (100).

[0055] [Note 3] The display unit (40) is a workpiece mass estimation device (100) as described in Appendix 1 or 2, which displays the graph (41) and the date and time (47) when the estimation of the mass was completed.

[0056] [Note 4] The display unit (40) is a workpiece mass estimation device (100) described in any one of the appendices 1 to 3, which displays the graph (41) and the temperature (48) of the motor (70) in real time.

[0057] [Note 5] The display unit (40) is a workpiece mass estimation device (100) according to any one of appendices 1 to 4, which displays the graph (41) and an operation pattern selection unit (44) for selecting the operating conditions of the driven body (Dv).

[0058] [Note 6] The display unit (40) displays the graph (41) and, if the estimation of the mass of the workpiece (W) is not completed successfully, displays a message (46) indicating that the estimation of the mass is incomplete, as described in any one of the appendices 1 to 5, the workpiece mass estimation device (100).

[0059] [Note 7] The display unit (40) displays the graph (41) and also displays a reset unit (43) for initializing the estimated mass, and is a workpiece mass estimation device (100) as described in any one of appendices 1 to 6.

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

[0061] [Note 9] The aforementioned graph (41) is, An inertia graph (41a) showing the change in the inertia of the driven body (Dv), A graph (4b1) showing the change in the viscous friction coefficient in the transmission system that transmits the output of the motor (70) to the workpiece loading section (90), A graph of the Coulomb friction coefficient (41c) showing the change in the Coulomb friction coefficient in the aforementioned transmission system, A spring constant graph (41d) showing the change in the spring constant in the aforementioned transmission system is included, A workpiece mass estimation device (100) as described in any one of the appendices 1 to 8.

[0062] According to the workpiece mass estimation device (100) described in appendices 1 to 9 above, it is possible to easily confirm whether or not the iterative calculation is being processed correctly.

[0063] Although the present disclosure has been described in detail above, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of the present disclosure or from the spirit of the present disclosure derived from the claims and their equivalents. Furthermore, these embodiments can be implemented in combination. For example, the order of operations and processes in the embodiments described above are shown as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above. [Explanation of symbols]

[0064] 10 Identification section 20 Memory section 30 Estimation part 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 section 44 Operation Pattern Selection Unit 46 Status Information 47. Date and Time Information 48 Temperature information 50 Motor control unit 60 sensors 70 Motor 90 Work Loading Section 100 Workpiece Mass Estimation Device 200 Machine tools (machinery) Double job

Claims

1. A machine having a workpiece loading section on which workpieces are loaded, a motor that drives the workpiece loading section, a sensor that detects the state of the motor, and a motor control unit that controls the motor based on the detected state of the motor, A workpiece mass estimation device for estimating the mass of the aforementioned workpiece, An identification unit identifies the values ​​of the physical parameters of the driven object driven by the motor's output based on the detected state of the motor, and updates the identified values ​​through iterative calculations. A memory unit that stores the updated values ​​of the aforementioned physical parameters, An estimation unit that estimates the mass of the workpiece from the final value when the updated physical parameter values ​​converge, A display unit that displays a graph showing the changes in the values ​​of the physical parameters associated with the iterative calculation based on the data stored in the memory unit, and also displays the mass estimated by the estimation unit. A workpiece mass estimation device equipped with the following features.

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

3. The workpiece mass estimation apparatus according to claim 1 or 2, wherein the display unit displays the graph and also displays the 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 unit displays the graph while simultaneously displaying the motor temperature in real time.

5. The workpiece mass estimation device according to claim 1 or 2, wherein the display unit displays the graph and also displays an operation pattern selection unit for selecting the operating conditions of the driven body.

6. The workpiece mass estimation device according to claim 1 or 2, wherein the display unit displays the graph and, if the estimation of the workpiece mass is not completed successfully, indicates that the estimation of the mass is incomplete.

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

8. The workpiece mass estimation device according to claim 1 or 2, wherein the display unit displays an alarm while displaying the graph when the identified physical parameter falls outside a predetermined range.

9. The aforementioned graph shows An inertia graph showing the change in the inertia of the driven object, A graph showing the change in the viscous friction coefficient in the transmission system that transmits the output of the motor to the workpiece loading section, A graph of the Coulomb friction coefficient showing the change in the Coulomb friction coefficient in the aforementioned transmission system, This includes a spring constant graph showing the change in the spring constant in the aforementioned transmission system, The workpiece mass estimation apparatus according to claim 1 or 2.

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