Input shaping method and apparatus for complex vibration using multi-frequencies with frequency range

Abstract

The present invention relates to a method for input shaping and an input shaping control device for the same, and in particular, to a method for input shaping capable of input shaping a complex vibration having a predetermined frequency range based on multiple frequencies and an input shaping control device for the same.

Description

Technology Field

[0001] The present invention relates to a method for input shaping and an input shaping control device for the same, and in particular, to a method for input shaping capable of input shaping a complex vibration having a predetermined frequency range based on multiple frequencies and an input shaping control device for the same. Background Technology

[0002] Vibration control is one of the important control technologies in various mechanical systems such as industrial robot arms, automation equipment, linear actuators, and motors. It is an important control technology that can solve the problem of reduced product stability and efficiency caused by unexpected residual vibrations when the system stops after operation.

[0003] Conventional vibration control technology involves measuring vibrations, selecting a primary single vibration to measure its frequency and damping ratio, and generating a motion profile to control the vibration based on the measured frequency and damping ratio, which is then applied to the mechanical system. While this method is suitable for controlling a single primary vibration, it has the problem that effective control is difficult in the case of complex vibrations, disturbances, or uncertain vibrations.

[0004] Therefore, there is a need to develop technology capable of controlling vibrations by more efficiently eliminating residual vibrations, even under complex and uncertain vibration conditions. Prior art literature

[0005] Korean Patent Publication No. 10-2023-0148099, published October 24, 2023 (Title: Management device, processing system, management method, and method for manufacturing an article) The problem to be solved

[0006] The present invention is proposed to solve the aforementioned conventional problems and aims to provide a method for input shaping a complex vibration having a predetermined frequency range based on multiple frequencies and an input shaping control device for the same.

[0007] However, the objectives of the present invention are not limited to the above objectives, and other unmentioned objectives will be clearly understood from the description below. means of solving the problem

[0008] A method for input shaping a composite vibration having a predetermined frequency range based on multiple frequencies according to an embodiment of the present invention for achieving the purpose described above, wherein the input shaping control device comprises: a step of acquiring a composite vibration having a predetermined frequency range from measurement data of an object operated according to an initial motion profile; a step of setting a target frequency range for vibration reduction within the predetermined frequency range; and a step of input shaping the composite vibration having the predetermined frequency range by calculating a composite impulse sequence using at least two frequencies within the target frequency range until all frequencies within the target frequency range become below a preset threshold value, and then applying it to the motion profile.

[0009] At this time, the motion profile may be a profile for a trajectory that includes at least position, velocity, and acceleration data.

[0010] In addition, the above measurement data is acceleration data, and the natural frequency can be extracted from the acceleration data using the Fast Fourier Transform (FFT), and the damping ratio can be extracted using the half-power technique.

[0011] In addition, the above target frequency range can be set by considering the impulse amplitude and time position of the complex vibration.

[0012] In addition, the input shaping step may comprise: a step of calculating a synthetic impulse sequence based on the lowest frequency and the highest frequency among the target frequency range; a step of checking the residual vibration percentage based on the calculated synthetic impulse sequence; a step of determining whether the residual vibration percentage is below a preset threshold, and if it is not below the preset threshold, a step of checking the peak frequency in the residual vibration percentage; a step of recalculating a synthetic impulse sequence based on a frequency corresponding to the natural frequency most similar to the lowest frequency, the highest frequency, and the peak frequency; a step of reconfirming the residual vibration percentage based on the recalculated synthetic impulse sequence, and repeating this step until the reconfirmed residual vibration percentage becomes below the preset threshold to calculate a final synthetic impulse sequence; and a step of applying the final calculated synthetic impulse sequence to the motion profile to reacquire measurement data of the operated object.

[0013] Additionally, the present invention may provide a computer-readable recording medium that records a program for executing the method described above.

[0014] In an input shaping control device for input shaping a composite vibration having a predetermined frequency range based on multiple frequencies according to an embodiment of the present invention for achieving the purpose described above, the device can input shaping a composite vibration having a predetermined frequency range by obtaining a composite vibration having a predetermined frequency range from measurement data of an object operated according to an initial motion profile, setting a target frequency range for vibration reduction within the predetermined frequency range, and calculating a composite impulse sequence using at least two frequencies within the target frequency range until all frequencies within the target frequency range become below a preset threshold value, and then applying it to the motion profile.

[0015] At this time, the input forming control device calculates a synthetic impulse sequence based on the lowest frequency and the highest frequency among the target frequency range, checks the residual vibration percentage based on the calculated synthetic impulse sequence, determines whether the residual vibration percentage is below a preset threshold, and if it is not below the preset threshold, performs a process of checking the peak frequency in the residual vibration percentage, a process of recalculating the synthetic impulse sequence based on the frequency corresponding to the natural frequency most similar to the lowest frequency, the highest frequency, and the peak frequency, and a process of reconfirming the residual vibration percentage based on the recalculated synthetic impulse sequence until the reconfirmed residual vibration percentage becomes below a preset threshold, thereby calculating a final synthetic impulse sequence, and then applies the final calculated synthetic impulse sequence to the motion profile to reacquire measurement data of the operated object. Effects of the invention

[0016] According to the method for input shaping a complex vibration having a predetermined frequency range based on multiple frequencies and the input shaping control device for the same according to the present invention, a complex vibration having a predetermined frequency range can be input shaping more efficiently based on multiple frequencies, and in particular, by using a target frequency range, vibrations within all frequency ranges can be reduced, thereby minimizing the residual time and enabling more efficient vibration suppression.

[0017] In addition, various effects other than those described above may be disclosed directly or implicitly in the detailed description according to the embodiments of the present invention to be described below. Brief explanation of the drawing

[0018] FIG. 1 is a diagram illustrating a control diagram of a robot arm controller including an input molding control device according to an embodiment of the present invention. FIGS. 2 to 7 are drawings for explaining a method of input forming in an input forming control device according to an embodiment of the present invention. FIGS. 8 to 10 are drawings illustrating the effects according to an embodiment of the present invention. Specific details for implementing the invention

[0019] In order to clarify the features and advantages of the means for solving the problem of the present invention, the present invention will be described in more detail with reference to specific embodiments of the present invention illustrated in the attached drawings.

[0020] However, detailed descriptions of known functions or configurations that may obscure the essence of the invention are omitted in the following description and the attached drawings. Additionally, it should be noted that identical components throughout the drawings are indicated by the same reference numerals whenever possible.

[0021] Terms and words used in the following description and drawings should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of terms to best describe his invention. Accordingly, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the invention and do not represent all aspects of the technical spirit of the invention; therefore, it should be understood that various equivalents and modifications capable of replacing them may exist at the time of filing this application.

[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0023] First, the input shaping technology according to an embodiment of the present invention will be described.

[0024] FIG. 1 is a diagram illustrating a control diagram of a robot arm controller including an input molding control device according to an embodiment of the present invention, FIG. 2 to 7 are diagrams illustrating a method of input molding in an input molding control device according to an embodiment of the present invention, and FIG. 8 to 10 are diagrams illustrating effects according to an embodiment of the present invention.

[0025] First, input molding technology refers to a control technology aimed at reducing vibration of an object. Here, the object may be an industrial robot arm operated by a robot arm controller (20) as shown in FIG. 1, but is not necessarily limited thereto, and any device that requires suppression of residual vibration, such as automation equipment, linear actuators, or motors, may be the object of the present invention.

[0026] For convenience of explanation, the following description will focus on the application of the input molding control device (10) of the present invention to a robot arm controller (20) that controls an industrial robot arm.

[0027] In the case of industrial robot arms, residual vibration may occur due to rapid deceleration at the final position when stopping during high-speed operation.

[0028] That is, referring to FIG. 1, the input forming control device (10) of the present invention, from the trajectory generated by the trajectory generator according to the initial motion profile, from the trajectory generated by the trajectory generator and It can be transmitted to the robot arm controller (20). Here, and represents joint angle (position), joint velocity, and joint acceleration, respectively.

[0029] And, the robot arm controller (20) performs the operation, , and It causes, here, represents residual vibration, and is the actual location, means actual speed, and represents the target torque based on the inverse dynamics model.

[0030] In particular, the multi-frequency based input shaping control device (10) according to an embodiment of the present invention can input shaping the generated residual vibration (ψ) to generate an impulse sequence and synthesize the generated impulse sequence with the trajectory of the target robot arm controller (20) to suppress the residual vibration.

[0031] In particular, the multi-frequency based input shaping control device (10) according to an embodiment of the present invention optimally shapes the input and transmits the shaped input to a robot arm controller (20) to form a trajectory according to the optimal joint angle, joint velocity, and joint acceleration.

[0032] At this time, the input shaping control device (10) of the present invention does not derive an optimal joint angle, joint velocity, and joint acceleration corresponding to a single vibration, but rather a composite impulse sequence (I) corresponding to a complex vibration having a predetermined frequency range, that is, a vibration in the form of multiple superpositions of frequencies. multi-mode It is possible to derive ) and apply the synthetic impulse sequence to a complex vibration having a predetermined frequency range to perform input shaping for the complex vibration.

[0033] We will explain this input shaping control method in more detail.

[0034] As described above, the basic principle of the input shaping control method of the present invention is to form an impulse sequence that eliminates residual vibration, using measurement data sensed from a sensor equipped on the mission body of the target object to determine the target object's natural frequency, i.e., natural frequency ( Modeling parameters of ) and damping ratio (ζ) are obtained. Here, the measurement data refers to the acceleration data of the object, and the sensor may include, for example, an Inertial Measurement Unit (IMU). However, the sensor of the present invention is not necessarily limited to an Inertial Measurement Unit, and the acceleration data may be measured using various sensing devices or algorithms capable of measuring the acceleration data of the object, such as a laser device like a Laser Doppler Vibrometer (LDV), a distance sensor, an encoder, or vision processing technology.

[0035] natural frequency ( A robot arm controller (20) having ) and damping ratio (ζ) can assume that the impulse transmitted from the input molding control device (10) consists of N impulses. The total response magnitude of the robot arm controller (20) located at the rear end of the input molding control device (10) can be expressed as Equation 1 below.

[0036] <Mathematical Formula 1>

[0037]

[0038] Here, And, It can be, and in this case, A i represents the impulse amplitude (magnitude), and t i It can indicate the time location where the impulse occurred (the time at which the shock occurred).

[0039] If only vibrations at a single dominant natural frequency are reduced during input shaping of a robot arm controller (20) satisfying the above-described response size, there is a problem that performance in other frequency ranges may decrease exponentially and the time required for input shaping may increase.

[0040] Accordingly, the input shaping control device (10) according to the embodiment of the present invention is designed to solve the above-mentioned problem by widening the damping band of a multi-mode impulse, which is a complex vibration having a predetermined frequency range, thereby controlling residual vibration and simultaneously optimizing and reducing the time for input shaping.

[0041] To explain more specifically the method of input shaping in such an input shaping control device (10), the input shaping control device (10) according to an embodiment of the present invention first uses the measurement data of the object to the object's natural frequency ( Modeling parameters of ) and damping ratio (ζ) can be obtained.

[0042] An object, such as an industrial robot arm, is a complex vibration containing multiple frequencies of residual vibration that can affect trajectory tracking, and when the number of damping modes is k, the transfer function can be defined as shown in the following mathematical formula.

[0043] <Mathematical Formula 2>

[0044]

[0045] Here, the damping ratio ζ can be significantly smaller than 1, and k can represent the total number of frequency modes, i.e., the number of frequencies included in the residual vibration.

[0046] Impulse sequence for multimode input shaping of transfer function G(s) It can be defined as shown in the following mathematical formula.

[0047] <Mathematical Formula 3>

[0048]

[0049] Here, and represents the amplitude and time position, respectively, of an input shaper having N impulses, where j is the index of a selected frequency range {1, ..., k} and k represents the frequency number. Synthetic impulse sequence It can be defined by the following mathematical formula.

[0050] <Mathematical Formula 4>

[0051]

[0052] In the case of 2-impulse zero oscillation, the amplitude impulse and time position can be defined by the following mathematical formula.

[0053] <Mathematical Formula 5>

[0054]

[0055] Here, represents an auxiliary constant.

[0056] The total decay period of all modes used to construct the impulse sequence may be equal to the final impulse time of the synthesized sequence. The last impulse time of the sequence and the induction rise time delay of the input shaping device can determine the length of the sequence rather than the number of impulses in the sequence. The time delay for an impulse sequence of k frequency modes generated by synthesizing a 2-impulse (N=2) shaping device for k frequencies can be defined as follows:

[0057] <Mathematical Formula 6>

[0058]

[0059] Subsequently, the amplitude (magnitude, A(ζ)) and time position t( of each impulse sequence ,ζ) can be defined according to the following mathematical formula.

[0060] <Mathematical Formula 7>

[0061]

[0062] In the above formula , , and It can be defined by the following mathematical formula.

[0063] <Mathematical Formula 8>

[0064]

[0065] Also, the amplitude (magnitude, A(ζ)) and time position t of the impulse sequence of the three frequency modes ( ,ζ) can be derived according to the following mathematical formula.

[0066] <Mathematical Formula 9>

[0067]

[0068]

[0069]

[0070] As described above, the synthetic impulse sequence of the present invention can be obtained by mathematical formula 4, and the impulse amplitude and time location It can be defined by mathematical formula 5.

[0071] The input shaping control device (10) of the present invention sets a target frequency range for vibration reduction to ensure robustness against modeling errors, and generates a synthetic impulse sequence using at least two frequencies within the target frequency range until all frequencies within the target frequency range become below a preset threshold. Here, the preset threshold may be a threshold for the percentage of residual vibration, for example, set to 5%. When the percentage of residual vibration is 5% or less, the vibration level can be reduced by at least 95%.

[0072] The percentage of residual vibration for this can be defined by the following mathematical formula.

[0073] <Mathematical Formula 10>

[0074]

[0075] Here, and Each The magnitude and time position of the impulse i of, and N is It is the impulse number of, and synthetic impulse train It refers to the last impulse time position. The above-mentioned mathematical equation 10 can be simply expressed as follows.

[0076] <Mathematical Formula 11>

[0077]

[0078] Here, It can be defined as follows.

[0079] <Mathematical Formula 12>

[0080]

[0081] To explain the process of using the percentage of residual vibration of the present invention with an example, when a predetermined frequency range of complex vibration is 10Hz to 30Hz, the input shaping control device (10) of the present invention, in order to reduce all vibrations in the frequency range, has the lowest frequency among the target frequency range ( ) 10Hz, highest frequency( A synthetic impulse sequence can be generated using 30Hz.

[0082] Accordingly, the input molding control device (10) of the present invention has a peak of residual vibration percentage. In order to identify, for We can analyze the derivative of and set it to 0.

[0083] The derivative of the residual vibration percentage of the above-described mathematical formula 12 can be expressed as follows:

[0084] <Mathematical Formula 13>

[0085]

[0086] Here, Each can be expressed as follows.

[0087] <Mathematical Formula 14>

[0088]

[0089] Here, the peak of the residual vibration percentage in Equation 13 is as follows: It can be determined by setting it to 0.

[0090] Here, and can refer to the peak frequency of the natural frequency at which the peak value and the percentage of residual vibration reach a maximum. Here, j is an index in the range {1, ..., k} and k can refer to the number of frequencies.

[0091] Subsequently, a synthetic impulse sequence can be generated based on the lowest frequency, highest frequency, and the natural frequency most similar to the peak frequency with the largest percentage within the target frequency range, and this process can be repeated and applied until all frequencies within the target frequency range fall below a preset threshold.

[0092] That is, when input shaping of a complex vibration having a predetermined frequency range, the input shaping control device (10) of the present invention does not use all frequencies to input shaping, but uses a target frequency range, and by using the target frequency range to reduce vibration within all frequency ranges, the residual time for the complex vibration is minimized, thereby enabling input shaping.

[0093] The process of generating a synthetic impulse sequence of the input shaping control device (10) of the present invention will be explained again with reference to FIGS. 2 to 7.

[0094] First, in Fig. 2, y(t) represents the residual vibration, and is a synthetic impulse sequence that minimizes the residual time. The residual vibration of the present invention refers to a complex vibration having a predetermined frequency range, that is, a vibration in the form of multiple frequencies superimposed, and the synthetic impulse sequence is an impulse sequence for input shaping by applying it to a motion profile (a profile for a trajectory including position, velocity, and acceleration data).

[0095] The input shaping control device (10) of the present invention sets a target frequency range for vibration reduction by considering the impulse amplitude and the time position where the impulse occurred, and uses FFT on the residual vibration, which is a composite vibration that is the measurement data (experimental data) as shown in FIG. 3, to determine the natural frequency ( ) extract ) and use the half-power technique to damping ratio ( Frequency (f1, f2, f3, f4, f5, f6) including ) can be extracted.

[0096] Subsequently, the input shaping control device (10) of the present invention synthesizes a convolution impulse sequence ( based on the lowest frequency (f1) and the highest frequency (f6) among the target frequency range. Can obtain ) (S100).

[0097] Here, convolution impulse sequence( Since it includes only the lowest frequency (f1) and the highest frequency (f6), it can take the form of the 2-mode composite impulse sequence of FIG. 7.

[0098] Then, the input shaping control device (10) determines whether the percentage of residual vibration is below a threshold value (e.g., 5%). If the percentage of residual vibration is not below a preset threshold value, the process of obtaining a synthetic impulse sequence again using a natural frequency most similar to the peak frequency can be repeated to obtain a final synthetic impulse sequence (S200).

[0099] More specifically, the percentage of residual vibration in the 2-mode synthetic impulse sequence of FIG. 7 is 44.59, which is above the threshold value, so the input shaping control device (10) of the present invention identifies the peak frequency in the percentage of residual vibration. Then, the frequency (f3) corresponding to the natural frequency most similar to the peak frequency is identified, and the synthetic impulse sequence can be regenerated based on the lowest frequency (f1), the highest frequency (f6), and the frequency (f3) corresponding to the natural frequency.

[0100] Since the composite impulse sequence at this time includes three frequencies, it may be the 3-mode frequency of FIG. 7, and since the 3-mode frequency also shows a residual vibration percentage of 15.35, which is above the threshold value, the input shaping control device (10) of the present invention can again check the peak frequency in the residual vibration percentage and check the frequency (f2) corresponding to the most similar natural frequency as shown in FIG. 5, and generate a composite impulse sequence by adding the confirmed f2 frequency, and the composite impulse sequence at this time is 5% or less as shown in FIG. 6, and can be confirmed that the residual vibration percentage of all frequencies has dropped below the threshold value.

[0101] As can be seen through FIGS. 8 to 10, the method of input forming in the input forming control device according to the embodiment of the present invention (proposed) enables high-efficiency vibration suppression compared to the prior art, suppresses residual vibration over a wide frequency range, and provides a reduced residual time.

[0102] The input forming method of the present invention has been described above.

[0103] The input forming method of the present invention as described above may be provided in the form of a computer-readable medium suitable for storing computer program instructions and data.

[0104] In particular, the computer program of the present invention, in a method for input shaping a complex vibration having a predetermined frequency range based on multiple frequencies, may perform the steps of: obtaining a complex vibration having a predetermined frequency range from measurement data of an object operated according to an initial motion profile; setting a target frequency range for vibration reduction within the predetermined frequency range; and calculating a composite impulse sequence using at least two frequencies within the target frequency range until all frequencies within the target frequency range become below a preset threshold value, and then applying it to the motion profile to input shaping the complex vibration having the predetermined frequency range.

[0105] Computer-readable media suitable for storing such computer program instructions and data include, for example, recording media such as magnetic media (e.g., hard disks, floppy disks, and magnetic tapes), optical recording media (e.g., CD-ROM, Digital Video Disk), and floptical disks (e.g., magneto-optical media), and semiconductor memories such as ROM (Read Only Memory), RAM (Random Access Memory), flash memory, EPROM (Erasable Programmable ROM), and EEPROM (Electrically Erasable Programmable ROM). Processors and memory may be supplemented by or integrated with special-purpose logic circuits.

[0106] Furthermore, computer-readable recording media may be distributed across networked computer systems, allowing computer-readable code to be stored and executed in a distributed manner. Additionally, the functional program for implementing the present invention, along with related code and code segments, may be easily inferred or modified by programmers skilled in the art to which the present invention pertains, taking into account the system environment of the computer that reads the recording media to execute the program.

[0107] In addition, a computer program recorded on a computer-readable recording medium as described above includes instructions that perform the functions described above, and can execute the aforementioned functions by being distributed and circulated through the recording medium, read, installed, and executed on a specific device or specific computer.

[0108] The present invention has been described with reference to embodiments illustrated in the drawings, but this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the true technical scope of protection of the present invention should be determined by the technical concept of the claims. Explanation of the symbols

[0109] 10: Input forming control device 20: Robot arm controller

Claims

Claim 1 A method for input shaping a complex vibration having a predetermined frequency range based on multiple frequencies, wherein the input shaping control device comprises: a step of acquiring a complex vibration having a predetermined frequency range from measurement data of an object operated according to an initial motion profile; a step of setting a target frequency range for vibration reduction within the predetermined frequency range; and a step of input shaping the complex vibration having the predetermined frequency range by calculating a composite impulse sequence using at least two frequencies within the target frequency range until all frequencies within the target frequency range become below a preset threshold value, and then applying the result to the motion profile. Claim 2 A method for forming an input according to claim 1, characterized in that the motion profile is a profile for a trajectory including at least position, velocity, and acceleration data. Claim 3 A method for shaping an input according to claim 1, wherein the measurement data is acceleration data, and the natural frequency is extracted from the acceleration data using a Fast Fourier Transform (FFT), and the damping ratio is extracted using a half-power technique. Claim 4 A method for shaping an input according to claim 1, wherein the target frequency range is set by taking into account the impulse amplitude and time position of the composite vibration. Claim 5 The method of input shaping according to claim 1, wherein the input shaping step comprises: a step of calculating a synthetic impulse sequence based on a minimum frequency and a maximum frequency among the target frequency range; a step of checking a residual vibration percentage based on the calculated synthetic impulse sequence; a step of determining whether the residual vibration percentage is below a preset threshold, and if it is not below the preset threshold, a step of checking a peak frequency in the residual vibration percentage; a step of recalculating a synthetic impulse sequence based on a frequency corresponding to the natural frequency most similar to the minimum frequency, the maximum frequency, and the peak frequency; a step of reconfirming the residual vibration percentage based on the recalculated synthetic impulse sequence, and repeating the steps until the reconfirmed residual vibration percentage becomes below a preset threshold to calculate a final synthetic impulse sequence; and a step of applying the final calculated synthetic impulse sequence to the motion profile to reacquire measurement data of the operated object. Claim 6 A computer-readable recording medium having a program that executes the input forming method described in any one of paragraphs 1 through 5. Claim 7 An input shaping control device for input shaping a complex vibration having a predetermined frequency range based on multiple frequencies, wherein the device acquires a complex vibration having a predetermined frequency range from measurement data of an object operated according to an initial motion profile, sets a target frequency range for vibration reduction within the predetermined frequency range, calculates a composite impulse sequence using at least two frequencies within the target frequency range until all frequencies within the target frequency range become below a preset threshold value, and then applies the result to the motion profile to input shaping the complex vibration having the predetermined frequency range. Claim 8 In claim 7, the input forming control device calculates a synthetic impulse sequence based on the lowest frequency and the highest frequency among the target frequency range, checks the residual vibration percentage based on the calculated synthetic impulse sequence, determines whether the residual vibration percentage is below a preset threshold, and if it is not below the preset threshold, checks the peak frequency in the residual vibration percentage, recalculates a synthetic impulse sequence based on a frequency corresponding to the natural frequency most similar to the lowest frequency, the highest frequency, and the peak frequency, and repeats the process of reconfirming the residual vibration percentage based on the recalculated synthetic impulse sequence until the reconfirmed residual vibration percentage becomes below a preset threshold, calculates a final synthetic impulse sequence, and then applies the final calculated synthetic impulse sequence to the motion profile to reacquire measurement data of the operated object.

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