JP4923796B2 - Swing simulation method and golf club design method - Google Patents

Description

  The present invention relates to a swing simulation method for a striking structure having a grip region and a non-grip region, such as a golf club, a baseball bat, and a tennis racket, and a golf club design method using this simulation method.

  Conventionally, a golfer's swing behavior is measured using an actual golf club, golf club grip coordinate time history data, grip tilt angle time history data, golf club shaft (hereinafter referred to as a shaft). ) Obtain the time history data of the rotation angle of the grip around the shaft axis, which is the geometrical central axis, and give swing motion to the golf club model based on these time history data, and twist the golf club model. In consideration of this, a golf swing simulation method for analyzing the swing behavior of a golf club by simulation is known (see, for example, Patent Document 1).

  A method of simulating golf club swing using a numerical swing model for swinging a golf club and a golf club model composed of a finite element model is also known (see, for example, Patent Document 2). Specifically, an arbitrary torque is input to the numerical swing model, and the swing is input by any of the above golf club models, and two changing elements among the three changing elements of the input torque, the golf club model head, and the shaft are input. Are the same, and one change factor is a design variable, and the head speed, the face angle, and the blow angle immediately before the impact during the swing in the golf club model are analyzed by a numerical swing model.

JP 2002-331060 A JP 2004-242855 A

  However, in the golf club simulation methods disclosed in Patent Documents 1 and 2, when a golf club model of a finite element model is created and a golfer's grip locus measured in a separate experiment is input to the grip portion, a simulation is performed. As described below, the shaft strain calculated by the simulation does not match the tendency of the shaft strain actually obtained by the person swinging, and the measured trend cannot be accurately reproduced by the simulation. there were.

  FIG. 11 shows a rigidly-constrained golf club model 40 in which a shaft model 42 and a grip model 46 are integrated and a head model 44 at the tip of the shaft model 46 is added.

FIG. 12A is a result of a person performing a golf swing using an actual golf club, and measuring the distortion of the shaft with a strain gauge. The change in the distortion of the shaft from the top of the swing to the impact is sometimes shown. Shown in series.
FIG. 12B is a simulation result by a golf club model of rigid restraint, and shows a change in the distortion of the shaft from the top of the swing to the impact in time series.
As is clear from the figure, the simulation result of FIG. 12B is different in tendency from the actual measurement result of FIG. That is, in this simulation, the behavior of the shaft distortion does not match the actual measurement result.

  In this simulation, shaft distortion, head speed, etc. calculated by the swing behavior of trial hitting robots and powerful male professional golfers tend to be relatively close to actual measurements, but for amateur golfers, the actual swing tendency is accurately reproduced. In other words, there is a problem that the simulation result does not necessarily match the actual measurement result due to a difference in golfers.

  The present invention solves the above-described problem, and is a swing simulation method capable of accurately reproducing a tendency of actual measurement, similar to a swing behavior by gripping with a human hand, and a golf club using the swing simulation method The purpose is to provide a design method.

To achieve the above object, the present invention provides a swing simulation method to reproduce the golf swing performed by gripping the golf club golfer, in preparing the golf club of model discretization in the finite element, The natural vibration when the grip part model and the golf club shaft model which the golfer holds by hand are separated, and the separated golf club shaft model and the grip part model are restrained by the grip part. coupled with the corresponding connecting element which defines the parameter values to lower than the natural frequency when the number represented by the model of one that is not separating the golf club shaft and the grip portion, said golf club shaft a model creating step of creating a soft constraint model is not fixed with respect to the grip portion, Sul The time series information of movement of the grip portion via the top of the state and the downswing state of ring to the state of the impact expressed by the position and orientation of the grip portion, corresponding to the grip portion of the soft constraint model portion in that it provides as a boundary condition, a reproduction step of reproducing the swing by calculating the dynamic behavior of the golf club, a calculation step of calculating a characteristic physical quantity of the golf club from the calculation results of the dynamic behavior of the golf club Thus, a swing simulation method is provided.
The connecting element is preferably either a spring element or a dashpot element. The connecting element is preferably a connecting element in which a spring element and a dashpot element are combined.
The spring element is defined by a translation spring element and a rotary spring element having three translational degrees of freedom and three rotational degrees of freedom, and the dashpot element is a translational dashpot having three translational degrees of freedom and three rotational degrees of freedom. Preferably it is defined by the element and the rotating dashpot element.
Preferably, the hitting structure is a golf club, the grip region is a grip portion, and the non-grip region is a golf club shaft.
The spring constant E of the spring element is preferably smaller than 5.8 × 10 ⁴ (kgf / mm).
The ratio E / C (1 / s) between the spring constant E (kgf / mm) of the spring element and the proportional viscosity coefficient C (kgf · s / mm) of the dashpot element is larger than 2.0 (1 / s). It is preferable.
The connecting element is preferably a contact element, beam element, truss element, connector element, mass element, solid element or shell element.
It is preferable to have a model correction step of determining whether or not the result calculated in the reproduction step matches a corresponding actual measurement value of the swing, and correcting the parameter value of the connection element based on the determination result.
Furthermore, the present invention provides a golf club design method characterized by designing a golf club based on a swing simulation result obtained by the swing simulation method.

  According to the present invention, by creating a soft restraint model that separates the gripping area from the non-gripping area and connects them with other finite elements, the measurement results of the swing behavior gripped with the hand of an elastic person can be accurately reproduced. This makes it possible to create a striking structure that reflects human behavior.

  Furthermore, when the present invention is applied to a golf club, it is possible to accurately reproduce shaft deformation and head speed when a person swings, and thus it is possible to reproduce a wide range of golfer swing behavior from amateurs to professionals. . Furthermore, it is possible to design a golf club that reflects the swing behavior of individual golfers.

  Hereinafter, a simulation method for a striking structure according to the present invention will be described in detail based on a preferred embodiment shown in the accompanying drawings. In the following description, a case where the striking structure is a golf club will be described.

FIG. 1 is a schematic configuration diagram of a calculation device 10 and a measurement system 20 that implement the golf club swing simulation method of the present invention.
The calculation device 10 reproduces the golf swing based on the golf club model using the three-dimensional time-series data representing the movement of the grip part 36 of the golf club represented by the position and orientation of the grip part 36 supplied from the measurement system 20. It is a device that performs calculations and calculates the characteristics of the golf swing measured using the calculation results. The calculation device 10 includes a model creation unit 12, a simulation calculation unit 14, and a determination unit 16. In addition, a CPU 18 that controls and manages the operation of each of the above parts, and a three-dimensional supplied from the measurement system 20. And a memory 19 for storing time-series data and processing results obtained in the above-described portions.

  Note that the calculation device 10 may be a computer configured to execute the functions of the model creation unit 12, the simulation calculation unit 14, and the determination unit 16 by executing a modularized subroutine program. In addition, a dedicated device in which each part is assembled by a dedicated device or a dedicated circuit may be used.

  The model creation unit 12 is a part that creates a golf club model that reproduces a golf club. The golf club model is a combination of a golf club head model, a golf club shaft model, and a grip model. The golf club shaft model is a straight beam model discretized with a beam element model having a constant cross-sectional area, and the golf club head model is exemplified by a mass point model in which concentrated mass is given at a position corresponding to the position of the center of gravity of the golf club head Is done. As the golf club model created by the model creation unit 12, an elastic body model of an elastic body in which the golf club shaft bends or a rigid body model in which the golf club shaft does not deform at all is created as necessary. The rigid body model can be easily created by making the value of the material constant related to the rigidity used for the elastic body model extremely large. Details of creating the golf club model will be described later.

  The simulation calculation unit 14 generates three-dimensional time series data representing the created golf club model and the movement of the grip unit 36 (see FIG. 1) of the golf club supplied from the measurement system 20 by the position and orientation of the grip unit 36. It is the part which performs the calculation process of the simulation calculation which reproduced and used golf swing. Specifically, the dynamic behavior of the golf club model is calculated by giving three-dimensional time series data as a boundary condition to a portion corresponding to the grip model 46 of the golf club model. Specifically, the calculation is performed by a known method that sequentially solves over time by an explicit method using a time difference scheme of the equation of motion.

  In this case, the three-dimensional time-series data supplied from the measurement system 20 includes the golf club grip portion 36 that reaches from the golf swing address state to the impact state through the back swing state, the top state, and the down swing state. It is data of movement. This three-dimensional time series data is given as a boundary condition to the grip model 46 to perform a simulation calculation.

The determination unit 16 is a part that determines whether or not the characteristic physical quantity of the golf club matches the actual measurement result from the calculation result obtained by the simulation calculation. As the characteristic physical quantity, for example, a moving speed (head speed) of a portion corresponding to the golf club head in the golf club model or a shaft deformation quantity (distortion) is calculated.
The calculation result of the golf swing is output to a printer or a monitor (not shown).
The calculation device 10 is configured as described above.

  On the other hand, the measurement system 20 includes a transmitter 20a that forms a magnetic field having a known distribution of strength and direction within a moving range of the grip portion 36 during golf swing performed by gripping the grip portion 36 of the golf club 30, and a grip. A receiver (magnetic sensor) 20b that outputs a signal including information on a three-dimensional position and a Euler angle with respect to a reference position by being fixed to the end of the unit 36 and sensing a magnetic field, and the grip unit 36 based on this signal A controller 20c for generating time series data of the three-dimensional positions (xm, ym, zm) and time series data of the Euler angles (θy, θp, θr) of the grip part 36.

  That is, as shown in FIG. 1, the measurement system 20 generates three types of predetermined magnetic fields one after another from a transmitter 20 a disposed and fixed behind a golfer who performs golf swinging, and is fixed to a grip unit 36 that moves and rotates. The received receiver 20b senses magnetism corresponding to the positions and orientations in the three types of magnetic fields created by the transmitter 20a and outputs a total of nine output voltages, and data processing is performed in the controller 20c from this output voltage. This is a system that can obtain data of the three-dimensional position and orientation (Euler angle) of the receiver 20b.

The measurement system 20 will be described in more detail. As shown in FIG. 2, a transmitter 20a that forms a predetermined magnetic field and a receiver 20b that generates an output voltage in three axial directions according to the strength and direction of the magnetic field. And a controller 20c.
The controller 20c generates a drive signal that sequentially generates predetermined three types of magnetic fields in the transmitter 20a, detects a signal output from the receiver 20b, performs data processing from the detected signal, performs a predetermined position, For example, the receiver 20b with respect to a three-dimensional position coordinate (xm, ym, zm) whose reference direction is the position of the transmitter 20a and three directions orthogonal to each other and a predetermined reference direction, for example, the X, Y, Z coordinate axis directions. Is calculated and output time-series data of posture angles representing the direction of the angle, that is, yaw angle, pitch angle and roll angle (hereinafter referred to as Euler angles (θy, θp, θr)).

As shown in FIG. 2, the transmitter 20a and the receiver 20b are configured by three coils wound in a loop shape in three axial directions orthogonal to each other, and the transmitter 20a is fixedly disposed behind the golfer who performs golf swing. The receiver 20b is fixed to the end of the grip portion 36 of the golf club 30.
The controller 20c controls a drive circuit 20d that generates a drive signal that sequentially generates three types of magnetic fields, a detection circuit 20e that detects a signal output from the receiver 20b, and the drive circuit 20d and the detection circuit 20e. The control unit 20f obtains the three-dimensional position and Euler angle of the receiver 20b from the signal sent from the detection circuit 20e. The transmitter 20a is connected to the drive circuit 20d, and the receiver 20b is connected to the detection circuit 20e.

  The measurement system 20 is configured as described above. The time series data of the three-dimensional position coordinates (xm, ym, zm) with respect to the reference position of the receiver 20b fixed to the grip portion 36 and the Euler angles (θy, θp, θr) with respect to the reference direction are obtained as follows. It is done.

  As shown in FIG. 2, the drive circuit 20d outputs the same signal whose frequency and phase are always constant according to the command signal of the control unit 20f, and has three loop coils wound in the three-axis directions of the transmitter 20a. Energize sequentially. Each loop-like coil generates a different magnetic field each time it is excited, and based on this magnetic field, three loop-like coils wound around the three axes of the receiver 20b generate independent voltages. Since this voltage is three independent voltages generated in the three loop coils of the receiver 20b in accordance with the three magnetic fields excited by the three loop coils of the transmitter 20a, a total of nine (3 × 3) voltage is obtained.

On the other hand, since the transmitter 20a for forming a magnetic field is fixedly installed at a predetermined position, the distribution regarding the strength and direction of the generated magnetic field is known with respect to the reference position and the reference direction where the transmitter 20a is installed. Therefore, by using nine voltages generated by the formed magnetic field, the three-dimensional position coordinates (xm, ym, zm) of the receiver 20b with respect to the reference position and the Euler angles (θy, θp, θr) with respect to the reference direction are determined. Six unknowns can be obtained.
The control unit 20f of the controller 20c calculates the three-dimensional position coordinates (xm, ym, zm) and Euler angles (θy, θp, θr) using the nine voltages sent from the detection circuit 20e. Ask.
The obtained three-dimensional position coordinates (xm, ym, zm) and Euler angles (θy, θp, θr) are supplied to a computer 22 which is a data processing unit.
An example of such a measurement system 20 is 3SPACE FASTRAK (manufactured by Polhemus).

  The computer 22 is orthogonal to the three-dimensional position based on the predetermined position of the grip portion 36 from the time-series data of the supplied three-dimensional position coordinates (xm, ym, zm) and Euler angles (θy, θp, θr). This is a part obtained by calculating three-dimensional time-series data regarding the orientation of the grip portion 36 in the three-dimensional direction in the coordinate system (XYZ coordinate system). For example, three-dimensional position coordinate (xm, ym, zm), azimuth and elevation angles in a Cartesian coordinate system, and three-dimensional time-series data of rotation around the axis of the golf club shaft 32 are obtained. The time-series data of the three-dimensional position of the grip part 36 and the direction of the grip part 36 in the three-dimensional direction in this orthogonal coordinate system is supplied to the calculation device 10 and stored in the memory 19.

  Further, the three-dimensional time-series data including the calculated three-dimensional position of the grip portion 36 and the orientation in the three-dimensional direction is the trajectory of the grip portion 36 viewed from the set predetermined direction, for example, from the front facing the golfer. It is converted into track data of the grip portion 36 during the seen golf swing and supplied to the monitor 24. Further, the three-dimensional time series data is displayed on the monitor 24 as a graph. The measurement system 20 is configured as described above.

In the calculation device 10 and the measurement system 20 as described above, the following golf swing simulation is performed.
FIG. 3 is a flowchart showing a flow of a golf club swing simulation method.

  First, the swing trajectory of the golf club is read. To do this, the golfer grips and swings the golf club, or swings the golf club by gripping the golf club, measures this using the measuring system 20, and reads it into the computer 22 (step S10).

  In the golf swing measurement, when a golf club with the receiver 20b fixed to the grip portion 36 is swung, the receiver 20b senses the magnetic field formed by the transmitter 20a and sends an output voltage to the controller 20c. The controller 20c calculates time-series data of the three-dimensional position coordinates (xm, ym, zm) and Euler angles (θy, θp, θr) by calculation, and from the time-series data, the computer 22 performs predetermined processing of the grip unit 36. Three-dimensional time-series data regarding the three-dimensional position on the basis of the position and the direction of the grip portion 36 in the three-dimensional direction in the orthogonal coordinate system is obtained. The obtained three-dimensional time series data, that is, three-dimensional position coordinates based on a predetermined position of the grip part 36 and data of the orientation of the grip part 36 in the three-dimensional direction are supplied to the calculation device 10 and are stored in the memory 19. Is remembered.

Next, input data for analysis by the finite element method (FEM) is created (step S11).
FIG. 4 shows a procedure for creating a golf club model.
FIG. 4A is a view showing a rigidly restricted golf club model. The golf club shaft model (non-gripping region model) 42 is a finite element model in which each element is discretized with a beam element model, and the beam element model of each element is a straight beam model with a constant cross-sectional area. . The golf club shaft model 42 is modeled by a straight beam model including elements 1 to 12, and a golf club head model ( non- gripping region) 44 is added to the tip end on the chip side. The golf club head model 44 is a mass point model in which the mass of the golf club head 34 is concentrated at a position corresponding to the position of the center of gravity of the golf club head 34. Further, the bat of the golf club shaft model 42 is provided with a grip model (gripping region model) 46 composed of the element 13 which is a rigid element.

  Note that the number of element divisions in the golf club shaft model 42 is not limited to 12 divisions, and may be 6 to 100 divisions. However, in the simulation calculation described later, it is 10 in terms of satisfying improvement in calculation efficiency and calculation accuracy at the same time. -15 divisions are preferable, and 12 divisions are more preferable. If the number of divisions is large, the calculation cannot be performed efficiently. On the other hand, if the number of divisions is small, the head speed described later cannot be accurately reproduced.

  Here, the material constant of each element 1-13 is the bending rigidity in the straight beam model in each element. The bending stiffness of the golf club shaft 32 changes along the longitudinal direction of the golf club shaft, and the value of the bending stiffness in each straight beam model is also changed along the longitudinal direction so as to correspond to this change.

Next, as shown in FIG. 4B, the shaft model 42 and the grip model 46 are separated (step S12). Next, as shown in FIG. 4C, the shaft model 42 and the grip model 46 are connected by a connecting element 48 such as a spring element or a dashpot element having a predetermined parameter value (spring constant, proportional viscosity coefficient). Setting is performed (step S13). Then, as shown in FIG. 4D, when the point A at the tip of the grip model 46, the point B at the connecting element 48, and the point C at the tip of the finite element 50 protruding from the connecting element 48, A, B, C Translational motion (x, y, z) at each point of A, ie, A (x _a , y _a , z _a ), B (x _b , y _b , z _b ), C (x _c , y _c , z _c) ) Expresses dynamic behavior in which points A, B, and C move to points A ′, B ′, and C ′.

The spring element or the dashpot element is used as the connecting element so that the simulation result of the golf club matches the result of the behavior of the golf club held by a human hand, as described in the subject of the present invention. It is to do.
The golf club model shown in FIG. 4C in which the shaft model 42 and the grip model 46 are connected by the connecting element is the same as that shown in FIG. 4A in which the golf club shaft model 42 and the grip model 46 before using the connecting element are integrated. ), The parameter values of the spring element and the dashpot element, that is, the spring constant E, so that the natural frequency of the first-order bending mode in the golf club model when the grip model 46 is fixed is decreased. And a proportional viscosity coefficient C are determined. That is, in the golf club model shown in FIG. 4C, the natural frequency of the primary bending mode of the golf club model when the grip model 46 is fixed corresponds to the golf club model shown in FIG. It is a soft constraint model that decreases compared to the natural frequency. Therefore, the golf club model shown in FIG. 4A is referred to as a rigid constraint model in contrast to the soft constraint model.
In the present invention, the soft restraint model is used as the golf club model because the primary bending mode of the golf club shaft changes depending on how the grip portion 36 of the actual golf club is restrained. Hereinafter, this point will be described.

  FIG. 5 shows an actual golf club, in a rigid restraint state (here, a state where the grip portion or the grip portion is fixed so as not to move) and a soft restraint state (here, a human hand). It is a figure which shows the result of having measured the natural frequency which a primary bending mode generate | occur | produces by holding | griping a grip part).

  Fig. 5 shows (1) rigid restraint, no grip rubber (fix the grip part without rubber in a vise), (2) rigid restraint, with grip rubber (fix the grip part with rubber in a vise), (3 ) Robot, with grip rubber (the robot grips the grip part with rubber), (4) Person (M), with grip rubber (M grips the grip part with rubber), (5) Person (M) The result of measuring the natural frequency (primary natural frequency) when the primary bending mode occurs in each state where grip rubber is present (the grip portion with rubber is gripped by Mr. S) is shown. The upper part is an example of a golf club A, and the lower part is an example of another golf club B. In FIG. 5, (1), (2) and (3) are rigid constraints, and (4) and (5) are soft constraints.

As is clear from FIG. 5, the natural frequency of the golf club in the case of human support (gripping by human) of (4) and (5) is the case of the rigid constraint of (1), (2), and (3) Is about 60 to 70% lower than the natural frequency of the golf club. Due to this difference in natural frequency, it is considered that the swing behavior by humans and the simulation results in the rigid constraint model do not match.
As described above, by using the soft restraint model using the spring element and the dashpot element for the golf club model, it is possible to reproduce the situation when a person holds the golf club.

Next, the simulation calculation unit 14 gives a boundary condition (three-dimensional time-series data representing the behavior of the grip) to the grip model 46 (the model of the grip region), and performs a simulation calculation that reproduces the golf swing (step S14). .
That is, three-dimensional time-series data from the golf swing address state to the back swing state, the top state, and the down swing state to the impact state is set as a boundary condition. The set boundary condition is stored in the memory 19.

  By applying the set boundary condition to the grip model 46 of the golf club model 40, the dynamic behavior of the golf club model 40 is calculated, and the dynamic behavior of the golf club model 40 moves along the time course by the explicit method using the time difference scheme of the equation of motion. The behavior is calculated, and the calculated characteristic physical quantity is output from the simulation calculation unit 14 (step S15). The determination unit 16 determines whether or not the calculated characteristic physical quantity matches the actual measurement result of the golfer's swing (step S16). If not, the golf club model is corrected (step S17). That is, the result that does not match is reflected in the correction of the parameter value of the spring / dashpot element.

FIG. 6 shows the result of top-impact analysis of the golf club model 40 when the above boundary condition is applied to the grip model 46 of the golf club model 40.
FIG. 6A shows that the shaft and the grip are connected by a spring element modeled with three translational degrees of freedom and three rotational degrees of freedom, and a constant E of the spring element is set to 2.0 × 10 ⁴ (kgf / mm), an example using a soft restraint model. FIG. 6B shows a spring element and a dashpot element that are also modeled with three translational degrees of freedom and three rotational degrees of freedom, and the spring constant E (kgf / mm) of the spring element and the dashpot element. An example of a soft constraint model in which the ratio (E / C) of the proportional viscosity coefficient constant C (kgf · s / mm) of E / C = 2000 (1 / s) is shown.

6A and 6B, in the example shown in FIGS. 6A and 6B, the golf club shaft model 42 is not greatly bent in an impact state and is almost in a straight state, and a person swings. It turns out that it becomes the behavior similar to.
FIG. 6C shows the result of top-impact analysis using a conventional rigid constraint model (the model shown in FIG. 4A). As is clear from the figure, it can be seen that the rigid constraint model has a large deflection in the impact state.

<Experiment 1>
FIG. 7 shows the result of a simulation experiment on the relationship between the spring constant (kgf / mm) of the spring element and the natural frequency (cpm) of the first-order bending mode using the rigid constraint model and the soft constraint model according to the present invention. As shown in the figure, in the case of the rigid restraint model, since there is no spring element itself, the frequency is always constant. In the case of the soft restraint model, the spring constant increases, so the frequency increases linearly. When the spring constant becomes 5.8 × 10 ⁴ , the same frequency as in the case of the rigid restraint is obtained. Therefore, in order to create the soft constraint model of the present invention, it is preferable that the spring constant is smaller than 5.8 × 10 ⁴ (kgf / mm).

<Experiment 2>
FIGS. 8A and 8B show the results of comparison between actual measurement results and simulation results obtained by measuring a change in shaft distortion on the face surface side in time series by swinging a golf club by a person holding it.
FIG. 8A is a diagram showing a simulation result. In FIG. 8, reference numeral 60 denotes a soft restraint golf club model using a spring element having a spring constant E of 2.0 × 10 ⁴ (kgf / mm). As a result of simulation, reference numeral 62 is a simulation result of a golf club model using a spring element having a spring constant E of 5.8 × 10 ⁴ (kgf / mm), and reference numeral 64 is a conventional rigidly restrained golf without using a spring element. The simulation results in the club model are shown respectively.
It can be seen that the soft restraint model simulation result of reference numeral 60 using the spring element is similar to the measured shaft distortion tendency shown in FIG.

<Experiment 3>
FIG. 9 shows the shaft strain of the rigid constraint model and the shaft strain of the soft constraint model at the final time (impact time) when the ratio (E / C) of the constant E of the spring element and the constant C of the dashpot element changes. It is a figure which shows how a difference changes. At this time, the spring element was kept constant at 2 × 10 ⁴ (kgf / mm), and the proportional viscosity coefficient of the dashpot element was changed. As shown in the figure, when E / C is 2.0 (1 / s) or less, the shaft distortion is the same as that of the rigid constraint model even in the soft constraint model, but when E / C is larger than 2.0, the soft strain model is soft. The difference in shaft distortion between the constraint model and the rigid constraint model increases. This shows that the shaft distortion at impact is smaller in the soft restraint model than in the rigid restraint model. Therefore, in the soft restraint model of the present invention using the spring element and the dashpot element, it is preferable to make E / C larger than 2.0 (1 / s).

<Experiment 4>
FIGS. 10A and 10B show actual measurement results and simulation results obtained by measuring a change in shaft distortion on the face surface side in time series by swinging a golf club held by a person. At this time, the spring element was kept constant at 2 × 10 ⁴ (kgf / mm), and the proportional viscosity coefficient of the dashpot element was changed.
FIG. 10A is a diagram showing a simulation result, in which reference numeral 70 denotes a simulation result of a soft restraint golf club model using a spring element and a dashpot element having an E / C of 2000 (1 / s), Reference numeral 72 is a simulation result of a soft restraint golf club model using a spring element and a dashpot element having an E / C of 2 (1 / s), and reference numeral 64 is a conventional rigid restraint golf club model using no spring element. The simulation results are shown respectively.
The soft restraint model simulation result of reference numeral 70 using a spring element and a dashpot element with an E / C of 2000 (1 / s) is similar to the measured shaft distortion tendency shown in FIG. I understand.
Thus, the simulation method of the present invention can reproduce the tendency of actual measurement.

  Although the simulation method of the present invention has been described above, a golf club can be designed using the result of the simulation method of the present invention. For example, the parameter values of the spring element and the dashpot element are determined according to the type of golfer (boy, girl, professional, amateur, etc.) and the power level of the golfer so that the head speed is maximized according to the type of golfer. Golf club shafts and golf club heads can be designed.

The swing simulation method and the golf club design method of the present invention have been described above in detail. However, the present invention is not limited to the above-described embodiment, and various improvements and modifications are made without departing from the gist of the present invention. Of course.
For example, the swing simulation method is not limited to golf clubs, and can be applied to baseball bats, tennis rackets, and other striking structures having a gripping area and a non-grip area. In addition, the connecting element is not limited to the spring element or the dashpot element, and the natural frequency of the model when the part gripped by a person is constrained is lower than a model in which the gripping area and the non-grip area are integrated. In this way, any contact element, beam element, truss element, connector element, mass element, solid element, or shell element used in the finite element method can be applied.

It is a schematic block diagram of the calculation apparatus and measurement system which implement the swing simulation method of this invention. It is a block diagram which shows the structure of the principal part of the measurement system shown in FIG. It is a flowchart which shows the flow of the swing simulation method of this invention. It is a figure which shows an example of the golf club of a rigid restraint model and a soft restraint model. It is a figure which shows the result of having measured the natural frequency in a rigid restraint and a soft restraint state. It is a deformation | transformation figure of the top-impact analysis of the golf club model of a soft restraint model and a rigid restraint model. It is a figure which shows the result of having experimented the relationship between the spring constant and frequency in a soft restraint model and a rigid restraint model. (A) is a simulation result of a soft restraint model and a rigid restraint model, (b) is a figure of the measurement result of the shaft distortion by a person's swing. It is a figure which shows the relationship between the shaft distortion of a rigid restraint model, and the difference of the shaft distortion of a soft restraint model. (A) is a simulation result of a soft restraint model and a rigid restraint model, (b) is a figure of the measurement result of the shaft distortion by a person's swing. This is a rigid golf club model in which a shaft and a grip are integrated. (A) is a figure which shows the actual measurement result by the swing of an actual golf club, (b) is a figure which shows the simulation result by the golf club model of the conventional rigid restraint.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Calculation apparatus 12 Model preparation part 14 Simulation calculating part 16 Judgment part 20 Measurement system 30 Golf club 32 Golf club shaft 34 Golf club head 36 Grip part 40 Golf club model (soft restraint model)
42 Golf club shaft (non-gripping area) model 44 Golf club head model 46 Grip (gripping area) model 48 Connecting element

Claims (9)

A swing simulation method for reproducing a golf swing performed by a golfer holding a golf club ,
When creating the golf club model discretized by a finite element, the golf club grip model and the golf club shaft model that the golfer grips by hand are separated, and the separated golf club shaft model and the The natural frequency when the grip portion is constrained with a model of the grip portion is reduced as compared with the corresponding natural frequency when the grip portion and the golf club shaft are represented by one model that is not separated. A model creating step of creating a soft restraint model in which the golf club shaft is not fixed to the grip portion by connecting with a connecting element that defines a parameter value to
The time series information of movement of the grip portion via the top state of the state and downswing of the swing to the state of the impact expressed by the position and orientation of the grip portion, corresponding to the grip portion of the soft constraint model portion A step of reproducing the swing by calculating the dynamic behavior of the golf club ,
Swing simulation method characterized by a calculation step of calculating a characteristic physical quantity of the golf club from the calculation results of the dynamic behavior of the golf club has.   The swing simulation method according to claim 1, wherein the connection element is either a spring element or a dashpot element.   The swing simulation method according to claim 1, wherein the connection element is a connection element combining a spring element and a dashpot element.   The spring element is defined by a translation spring element and a rotary spring element having three translational degrees of freedom and three rotational degrees of freedom, and the dashpot element is a translational dashpot having three translational degrees of freedom and three rotational degrees of freedom. 4. The swing simulation method according to claim 2, wherein the swing simulation method is defined by an element and a rotating dashpot element. The simulation method according to claim 2, wherein a spring constant E of the spring element is smaller than 5.8 × 10 ⁴ (kgf / mm). The ratio E / C (1 / s) between the spring constant E (kgf / mm) of the spring element and the proportional viscosity coefficient C (kgf · s / mm) of the dashpot element is larger than 2.0 (1 / s). The simulation method according to any one of claims 2 to 5, wherein: The simulation method according to any one of claims 1 to 6, wherein the connecting element is any one of a contact element, a beam element, a truss element, a connector element, a mass element, a solid element, and a shell element. . The method includes a model correction step of determining whether or not a result calculated in the reproduction step matches a corresponding actual measurement value of a swing, and correcting a parameter value of the connection element based on the determination result. Item 8. The swing simulation method according to any one of Items 1 to 7 . Golf club design method characterized by designing the golf club based on the swing simulation results for swing simulation method according to any one of claims 1-8.

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