Action program generation device and action program generation method for cogging torque correction

Abstract

This automates the generation of motion programs, reducing the workload of operators. The motion program generation device for cogging torque correction includes: a receiving unit that obtains mechanical structure information from a numerical control device, the mechanical structure information including at least one of the number of poles and slots of the motor, or including information associated with at least one of the number of poles and slots of the motor; a motion program generation unit that generates a motion program for cogging torque correction based on the mechanical structure information; and a sending unit that sends the generated motion program to the numerical control device. At least one of the number of poles and slots of the motor can be obtained from the numerical control device, or it can be obtained from a storage unit according to the type of motor, the storage unit storing a table that maps at least one of the number of poles and slots of the motor to the type of motor.

Description

Technical Field

[0001] This invention relates to an apparatus and method for generating motion programs for correcting tooth cogging torque, and particularly to an apparatus and method for automatically generating motion programs for correcting tooth cogging torque. Background Technology

[0002] Regarding cogging torque and its correction, for example, it is described in Patent Document 1, Patent Document 2, Patent Document 3 and Patent Document 4.

[0003] Patent Document 1 describes an electric motor control system in which no-load operation or other work is required before assembling the servo motor into the machine, and optimal cogging correction is performed independently of the combination of the servo motor and the servo amplifier.

[0004] Specifically, Patent Document 1 describes an electric motor control system in which a correction data memory for storing correction data of the cogging torque of the servo motor is provided in a position detector connected to a servo motor. The correction data is sent to a servo amplifier through a correction data transceiver unit. The servo amplifier receives the correction data from the position detector and uses the correction data received from the position detector to correct the cogging torque.

[0005] Patent document 2 describes a machine learning device that can easily minimize the amount of error in an electric motor.

[0006] Specifically, Patent Document 2 describes a machine learning device that learns conditions associated with correction amounts of commands from a motor control device. This machine learning device comprises: a state observation unit that observes state variables consisting of at least one of the following: data related to an error quantity, the operation program of the motor control device, any one of the position command, speed command, and current command of the motor control device, data related to workpiece machining conditions of a machine tool having a motor control device, and data related to the state of the machine tool having a motor control device, wherein the error quantity is the error between the position command of the rotor of the motor driven by the motor control device and the actual position of the feed mechanism; and a learning unit that learns conditions associated with correction amounts for correcting the aforementioned commands based on a training dataset composed of the state variables.

[0007] Patent document 3 describes an analytical device that can easily and quickly predict the performance of an electric motor whose performance is determined by various design factors.

[0008] Specifically, Patent Document 3 describes an analysis device equipped with a magnetization calculation GUI module and a model generation & torque calculation GUI module. The analysis device activates the magnetization calculation GUI module to calculate the magnetization distribution in the rotor magnets and generate a magnetization distribution file. Next, the analysis device activates the model generation & torque calculation GUI module, using the magnetization distribution file to generate a torque result file and a magnetic flux density distribution file. Here, the torque result file represents the torque variation at each rotation angle of the rotor; cogging torque is calculated when no drive current flows, and drive torque is calculated when drive current flows. Furthermore, the actual torque is calculated by subtracting the cogging torque from the drive torque. The magnetic flux density distribution file represents the magnetic flux density distribution flowing through the motor corresponding to the rotor's rotation angle, the force acting on the rotor, and the eddy current distribution flowing through the stator.

[0009] Patent document 4 describes an electric motor control device that can calculate an appropriate cogging torque correction amount even when a torque command for a constant low-speed feed operation is superimposed with components other than cogging torque (such as gravitational torque).

[0010] Specifically, Patent Document 4 describes an electric motor control device comprising: a torque command observation unit that observes the torque command when the electric motor operates at a constant speed; an approximate calculation unit that approximates the torque command approximates based on the observed torque command within an integer multiple of the period of the cogging torque of the electric motor; a second torque command calculation unit that calculates a second torque command by subtracting the torque command approximates from the torque command; a second torque command frequency analysis unit that extracts frequency components that are integer multiples of the fundamental frequency of the cogging torque by performing frequency analysis on the calculated second torque command; and a cogging correction calculation unit that calculates the cogging correction based on the amplitude and phase of the extracted frequency components.

[0011] Existing technical documents

[0012] Patent documents

[0013] Patent Document 1: Japanese Patent Application Publication No. 2001-037280

[0014] Patent Document 2: Japanese Patent Application Publication No. 2017-102613

[0015] Patent Document 3: Japanese Patent Application Publication No. 2003-141186

[0016] Patent Document 4: Japanese Patent Application Publication No. 2011-135645 Summary of the Invention

[0017] The problem that the invention aims to solve

[0018] The correction of the cogging torque of the built-in synchronous motor is required after mechanical installation.

[0019] Adjusting the correction parameters for cogging torque requires manual measurement and setting corresponding to the motor, generating the action program, and performing multiple data measurements.

[0020] To automate the generation of motion programs in this process and reduce the operator's workload, a motion program generation device and a motion program generation method for cogging torque correction are desired.

[0021] Methods for solving problems

[0022] A representative first aspect of this disclosure is an action program generation apparatus for cogging torque correction, comprising: a receiving unit that obtains mechanical structure information from a numerical control device, the mechanical structure information including at least one of the number of poles and the number of slots of an electric motor, or including information associated with at least one of the number of poles and the number of slots of the electric motor; an action program generation unit that generates an action program for cogging torque correction based on the mechanical structure information; and a sending unit that sends the generated action program to the numerical control device.

[0023] A representative second aspect of this disclosure is a method for generating an action program for cogging torque correction, wherein a computer performs the following processes: processing to obtain mechanical structure information from a numerical control device, the mechanical structure information including at least one of the number of poles and the number of slots of an electric motor, or including information associated with at least one of the number of poles and the number of slots of the electric motor; processing to generate an action program for cogging torque correction based on the mechanical structure information; and processing to send the generated action program to the numerical control device. Attached Figure Description

[0024] Figure 1 This is a block diagram illustrating a structural example of a control system for a motion program generation device for cogging torque correction, which includes an embodiment of the present invention.

[0025] Figure 2 This is a characteristic diagram representing an example of phase data and torque commands.

[0026] Figure 3 This is a diagram representing an example of the generated program.

[0027] Figure 4 This section describes a structural example where the shaft driven by an electric motor is a rotating shaft with an eccentric load.

[0028] Figure 5 This is an example of a procedure for a rotating shaft driven by an electric motor and subjected to an eccentric load.

[0029] Figure 6 This is a flowchart representing an example of an action procedure generation method.

[0030] Figure 7 This is a block diagram illustrating a structural example of a control system for a gear cogging torque correction motion program generation device, which includes a modified embodiment of the present invention. Detailed Implementation

[0031] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0032] Figure 1 This is a block diagram illustrating a structural example of a control system for a motion program generation device for cogging torque correction, which includes an embodiment of the present invention.

[0033] like Figure 1 As shown, the control system 10 includes a motion program generation device 100 for cogging torque correction, a numerical control device 200, an industrial machine 300, and a cogging torque correction parameter adjustment device 400. The motion program generation device 100 may be included in the cogging torque correction parameter adjustment device 400 or in the numerical control device 200.

[0034] The motion program generation device 100 obtains mechanical structure information, including at least one of the number of poles and slots of the motor, from the numerical control device 200, generates a motion program for cogging torque correction (hereinafter referred to as the motion program) based on the obtained number of poles and slots of the motor, and sends the generated motion program to the numerical control device 200.

[0035] The numerical control device 200 generates control commands such as position commands based on the received motion program and outputs the generated control commands to the industrial machine 300, causing the motor of the industrial machine 300 to operate and obtaining motion waveform data from the industrial machine 300. The motion waveform data includes data required for cogging torque correction, such as torque commands, and phase data (representing the armature rotation angle, with one pole pair corresponding to 0~360 degrees) output from a rotary encoder installed on the motor. The numerical control device 200 sends the motion waveform data to the cogging torque correction parameter adjustment device 400, receives correction parameters from the cogging torque correction parameter adjustment device 400, and outputs them to the industrial machine 300. Correction parameters can also be output from the cogging torque correction parameter adjustment device 400 to the industrial machine 300 without going through the numerical control device.

[0036] Figure 2 The characteristic diagram represents an example of phase data and torque commands.

[0037] Industrial machinery 300 refers to machine tools or robots, etc. Industrial machinery 300 includes an electric motor and a servo control device for controlling the motor. The servo control device generates torque commands based on control commands such as position commands output from the numerical control device 200, controls the motor, and outputs motion waveform data to the numerical control device 200.

[0038] The industrial machine 300 uses correction parameters output from the numerical control unit 200 to generate a cogging correction torque, and adds it to the torque command from the servo control unit. The servo control unit controls the motor based on the torque command after cogging torque correction. The correction parameters are generated by the cogging torque correction parameter adjustment device 400.

[0039] The cogging torque correction parameter adjustment device 400 outputs correction parameters based on motion waveform data. Devices that output correction parameters based on motion waveform data are known. For example, Patent Document 4 describes a cogging correction parameter calculation unit that generates correction parameters (frequency, amplitude, and phase) based on torque commands and the position (reference phase) of the motor output from an encoder installed on the motor, and then outputs them.

[0040] Furthermore, it is known that an industrial machine 300 uses a correction parameter output from a cogging torque correction parameter adjustment device 400 to generate a cogging correction torque. For example, Patent Document 4 describes a motor control device having the following structure: a cogging correction torque is generated using correction parameters (frequency, amplitude, and phase), and added to a torque command; the motor is then controlled based on the torque command after cogging torque correction.

[0041] The structure of the action program generation device 100 will be described below.

[0042] The motion program generation device 100 includes a receiving unit 110, an motion program generation unit 120, and a sending unit 130.

[0043] The receiving unit 110 obtains mechanical structure information from the numerical control device 200, including at least one of the number of poles and the number of slots of the electric motor.

[0044] The motion program generation unit 120 generates a motion program based on mechanical structure information including at least one of the number of poles and the number of slots of the electric motor.

[0045] First, the motion program generation unit 120 calculates the generation cycle of the cogging torque based on at least one of the number of poles and slots of the motor contained in the mechanical structure information. Then, the motion program generation unit 120 generates a motion program that enables the acquisition of cogging torque data for more than one cycle.

[0046] The sending unit 130 sends the action program to the numerical control device 200.

[0047] (Example of program generation)

[0048] As an example of program generation, an example of program generation when the shaft driven by the electric motor is a rotating shaft with eccentric load will be explained. In the following explanation, an example of generating an action program based on the number of poles and slots of the electric motor obtained from the numerical control device 200 will be described.

[0049] The receiving unit 110 obtains mechanical structure information from the numerical control device 200, including the number of poles of the motor, the number of slots, the eccentric load, and the direction of the gravity load.

[0050] The motion program generation unit 120 calculates the generation period of cogging torque based on the number of poles and slots of the motor. For example, when the motor has 8 poles and 9 slots, the generation period of cogging torque is 360 degrees divided by 72, which is the least common multiple of 8 and 9, resulting in 5 degrees. Therefore, the motion program generation unit 120 generates a motion program that sets the movement amount so that the rotation angle of the motor is 5 degrees or more.

[0051] Figure 3 This represents an example of the generated action program.

[0052] In the case where the shaft driven by the electric motor is a rotating shaft (rotating tilting shaft) with eccentric load, the following points are also considered when generating the motion program.

[0053] like Figure 4 As shown, when the shaft driven by the electric motor is a rotating shaft (rotating tilting shaft) with an eccentric load, the effect of gravity varies with angle θ. That is, the rotational component of gravity varies with angle θ. Therefore, the force required to hold the shaft, i.e., the torque offset, varies with angle θ.

[0054] Thus, in a rotating shaft with an eccentric load, the effect of gravity increases with the shaft angle, reducing the accuracy of cogging torque correction. To perform high-precision cogging torque correction, the receiving unit 110 obtains information on the eccentric load and the direction of the gravity load from the numerical control device 200, and generates a program that minimizes the effect of gravity (the force required to maintain shaft stability). Figure 4 In the example, the effect of gravity becomes smaller when the angle θ is near 0 degrees.

[0055] The motion program generation unit 120 generates a motion program that operates within the range of -2.5 degrees to 2.5 degrees in the angle θ of the A-axis (rotation axis), so that the generation cycle of the cogging torque is 5 degrees and the angle θ is near 0 degrees.

[0056] Figure 5 This is an example of a procedure for a rotating shaft driven by an electric motor and subjected to an eccentric load.

[0057] The above describes a program generation example for generating an action program based on the number of poles and slots of an electric motor. However, if the number of poles or slots of the electric motor used in the industrial machine 300 is already determined, the other of the number of poles and slots of the electric motor can be obtained from the numerical control device 200, and an action program can be generated based on the other of the number of poles and slots of the electric motor.

[0058] Next, a flowchart will be used to illustrate the motion program generation method of the motion program generation device 100.

[0059] Figure 6 This is a flowchart representing an example of an action procedure generation method.

[0060] In step S11, the receiving unit 110 obtains mechanical structure information from the numerical control device 200, including at least one of the number of poles and the number of slots of the motor.

[0061] In step S12, the motion program generation unit 120 determines the generation cycle of the cogging torque based on at least one of the number of poles and the number of slots of the motor.

[0062] In step S13, the motion program generation unit 120 generates a motion program, enabling the acquisition of cogging torque data for more than one cycle.

[0063] In step S14, the sending unit 130 sends the action program to the numerical control device 200.

[0064] The motion program generation apparatus 100 of this embodiment described above can automate the generation of motion programs, thereby reducing the burden on operators.

[0065] (Variation example)

[0066] Figure 7 This is a block diagram illustrating a structural example of a control system for a gear cogging torque correction motion program generation device, which includes a modified embodiment of the present invention.

[0067] The control system 10A replaces the motion program generation device 100 of the control system 10 with the motion program generation device 100A.

[0068] The motion program generation apparatus 100A includes a storage unit 140 that stores a table mapping at least one of the number of poles and slots of a motor to the type of motor. The type of motor is information associated with at least one of the number of poles and slots of the motor. The receiving unit 110 obtains mechanical structure information including the type of motor from the numerical control device 200, and the motion program generation unit 120 searches the storage unit 140 based on the type of motor to obtain at least one of the number of poles and slots of the motor. The motion program generation unit 120 may also have the storage unit 140 externally.

[0069] To implement the functional blocks included in the action program generation apparatus in the above embodiments, the action program generation apparatus can be implemented by hardware, software, or a combination thereof. Here, implementation by software means implementing it by reading and executing the program by a computer.

[0070] In order to implement the structural components included in the motion program generation device through software or a combination thereof, the motion program generation device includes an arithmetic processing unit such as a CPU (Central Processing Unit). The arithmetic processing unit functions as an execution unit. In addition, the motion program generation device also includes auxiliary storage devices such as HDDs (Hard Disk Drives) that store various control programs such as application software or operating systems (OS), and main storage devices such as RAMs (Random Access Memory) that store data temporarily needed by the arithmetic processing unit when executing programs.

[0071] Furthermore, the processing unit of the motion program generation device reads application software or operating system from the auxiliary storage device, expands the read application software or operating system in the main storage device, and performs calculations based on these application software or operating system. Additionally, based on the calculation results, it controls various hardware components of the motion program generation device. Thus, the functional blocks of this embodiment are implemented.

[0072] The structural components of an action program generation device can be implemented using hardware, including electronic circuits. When the action program generation device is constructed from hardware, for example, integrated circuits (ICs) such as ASICs (Application Specific Integrated Circuits), gate arrays, FPGAs (Field Programmable Gate Arrays), and CPLDs (Complex Programmable Logic Devices) can constitute part or all of the functions of the structural components included in the action program generation device.

[0073] The above examples illustrate how motion program generation devices can be implemented through hardware, software, or a combination thereof, but the same applies to numerical control devices and gear cogging torque correction parameter adjustment devices.

[0074] Programs can be stored and provided to a computer using various types of non-transitory computer-readable media. Non-transitory computer-readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (e.g., hard disk drives), optical-magnetic recording media (e.g., optical discs), CD-ROMs (Read Only Memory), CD-Rs, CD-R / Ws, and semiconductor memories (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash memory ROMs, and RAMs (Random Access Memory)). Additionally, programs can also be provided to a computer using various types of transient computer-readable media.

[0075] Based on the above-described embodiment and its variations, the motion program generation apparatus and method can automate the generation of motion programs and reduce the workload of operators.

[0076] The above-described embodiments are preferred embodiments of the present invention, but the scope of the present invention is not limited to the above-described embodiments. Various modifications can be made without departing from the spirit of the present invention.

[0077] Regarding the above-described embodiments, the following notes are further disclosed.

[0078] (Note 1)

[0079] An apparatus for generating a motion program for cogging torque correction includes: a receiving unit (110) that obtains mechanical structure information from a numerical control device (200), the mechanical structure information including at least one of the number of poles and the number of slots of an electric motor, or including information associated with at least one of the number of poles and the number of slots of the electric motor; an motion program generation unit (120) that generates a motion program for cogging torque correction based on the mechanical structure information; and a sending unit (130) that sends the generated motion program to the numerical control device (200).

[0080] (Note 2)

[0081] According to the motion program generation apparatus described in Appendix 1, the motion program generation apparatus includes a storage unit (140) that stores a table that maps at least one of the number of poles and slots of the motor to the type of the motor. The receiving unit (110) obtains mechanical structure information from the numerical control device (200), which includes information about the type of motor associated with at least one of the number of poles and slots of the motor. The motion program generation unit (120) obtains at least one of the number of poles and slots of the motor from the storage unit based on the type of motor obtained from the numerical control device (200), and generates the motion program for tooth cogging correction based on at least one of the number of poles and slots of the motor.

[0082] (Note 3)

[0083] According to the motion program generation apparatus described in Appendix 1 or 2, the motion program is a program that includes movement of more than one cycle equivalent to the cogging torque of the electric motor.

[0084] (Note 4)

[0085] According to the apparatus described in Appendix 3, the mechanical structure information includes information related to the direction of the eccentric load and the gravitational load on the shaft driven by the electric motor, and the motion program generation unit (120) generates the motion program for performing actions in the region where the influence of the eccentric load and the gravitational load is small.

[0086] (Note 5)

[0087] A method for generating an action program for cogging torque correction, wherein a computer performs the following processes: receiving mechanical structure information from a numerical control device (200), the mechanical structure information including at least one of the number of poles and the number of slots of an electric motor, or including information associated with at least one of the number of poles and the number of slots of the electric motor; generating an action program for cogging torque correction based on the mechanical structure information; and sending the generated action program to the numerical control device (200).

[0088] Explanation of reference numerals in the attached figures

[0089] 10 Control System

[0090] 100 Gear Cogging Torque Correction Motion Program Generation Device

[0091] 110 Receiving Department

[0092] 120 Action Program Generation Department

[0093] 130 Sending Department

[0094] 140 Storage Division

[0095] 200 numerical control device

[0096] 300 Industrial Machinery

[0097] 400 Gear Cogging Torque Correction Parameter Adjustment Device.

Claims

1. A motion program generation device for cogging torque correction, characterized in that, have: The receiving unit obtains mechanical structure information from the numerical control device, which includes at least one of the number of poles and the number of slots of the motor, or includes information associated with at least one of the number of poles and the number of slots of the motor. The motion program generation unit generates a motion program for tooth groove correction based on the mechanical structure information. as well as The sending unit sends the generated action program to the numerical control device.

2. The motion program generation device according to claim 1, characterized in that, The motion program generation device includes a storage unit that stores a table that maps at least one of the number of poles and slots of the electric motor to the type of electric motor. The receiving unit obtains mechanical structure information from the numerical control device, which includes information about the type of motor associated with at least one of the number of poles and slots of the motor. The motion program generation unit obtains at least one of the number of poles and slots of the motor from the storage unit based on the type of motor obtained from the numerical control device, and generates the motion program for tooth groove correction based on at least one of the number of poles and slots of the motor.

3. The motion program generation device according to claim 1 or 2, characterized in that, The action program is an action program that includes a movement of more than one cycle, equivalent to the cogging torque of the electric motor.

4. The motion program generation device according to claim 3, characterized in that, The mechanical structure information includes information related to the direction of the eccentric load and gravitational load on the shaft driven by the electric motor. The motion program generation unit generates the motion program that performs the action in the region where the influence of the eccentric load and the gravity load is small.

5. A method for generating a motion program for cogging torque correction, characterized in that, The computer performs the following processing: Processing of obtaining mechanical structure information from a numerical control device, the mechanical structure information including at least one of the number of poles and the number of slots of an electric motor, or including information associated with at least one of the number of poles and the number of slots of the electric motor; Based on the mechanical structure information, a processing procedure for generating a tooth groove correction motion is generated; as well as The generated action program is sent to the numerical control device for processing.

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