JP6900795B2 - Analysis method of resultant force - Google Patents

Description

The present disclosure relates to a method for analyzing resultant forces.

For example, in an object such as a seat on which the human body sits, it is necessary to evaluate the reaction force received by the human body from the object (that is, the seat) in order to improve stability and sitting comfort. This reaction force is distributed as pressure on the surface of the human body.

As a method for evaluating the reaction force received by the human body from an object, for example, a method for obtaining the reaction force using a sensor such as a reaction force meter is known (see Patent Document 1). However, this method has not been developed for elastic bodies that deform like sheets. Therefore, the reaction force is also measured using a body pressure measuring sheet capable of following the deformation.

Japanese Unexamined Patent Publication No. 3-103272

With the above-mentioned body pressure measuring sheet, the vertical component (that is, normal force) of the reaction force on the contact surface between the human body and the object can be measured, but the shear component (that is, the frictional force) cannot be measured. Therefore, it is not possible to evaluate the stability sufficiently by the conventional technique.

One aspect of the present disclosure is an object of the present invention to provide a method for analyzing a resultant force capable of evaluating the behavior of a human body in contact with an elastic object.

One aspect of the present disclosure is a method of analyzing the resultant force of the reaction force received from the human body or the doll when a load is applied to the elastic object by the human body or a doll imitating the human body. The method of analyzing the resultant force includes a step of obtaining the distribution of the reaction force received from the object by the human body or the doll on the contact surface between the object and the human body or the doll (S20), and a step of obtaining the resultant force by combining the distribution of the reaction forces (S30). A step of obtaining the action line of the resultant force (S40) and a step of outputting the action line of the resultant force (S60) by using the balance of moments in the human body or the doll are provided.

According to such a configuration, the resultant force is obtained from the distribution of the reaction force, and the action line of the resultant force is output. Therefore, the stability of the human body or the doll can be visually evaluated by the visualized action line. Further, since the work line of the resultant force can be output in consideration of the frictional force, the behavior of the human body or the doll can be evaluated more realistically.

One aspect of the present disclosure may further include a step (S50) of determining the center of gravity of the human body or the doll. Further, in the output step (S60), the center of gravity of the human body or the doll may be output. According to such a configuration, the positional relationship between the center of gravity of the human body or the doll and the action line of the resultant force can be grasped, so that the behavior of the human body or the doll can be evaluated more effectively.

In one aspect of the present disclosure, in the step (S20) of obtaining the distribution of the reaction force, the distribution of each component force may be obtained by decomposing the reaction force into two or more component forces. Further, in the step of obtaining the resultant force (S30), the resultant force for each component force may be obtained. According to such a configuration, the reaction force can be decomposed into component forces in arbitrary directions and visualized, so that the optimum evaluation can be performed according to the shape of the object, the usage condition, and the like.

In one aspect of the present disclosure, the two or more component forces may be normal force and frictional force. According to such a configuration, for example, the behavior due to the reaction force with respect to the human body or the doll seated on the seat can be evaluated more accurately.

In one aspect of the present disclosure, in the step (S20) of obtaining the distribution of the reaction force, the reaction force may be obtained by the finite element method. Further, in the output step (S60), the action line of the resultant force may be output on the analysis result of the finite element method. According to such a configuration, workability is improved because the calculation for obtaining the resultant force and the confirmation of the output result of the action line of the resultant force can be performed on the same screen.

One aspect of the present disclosure may further include a step (S70) of evaluating the stability of the human body or the doll based on the output line of action of the resultant force. According to such a configuration, the stability of the human body can be evaluated more easily and accurately than before.

The reference numerals in the parentheses are examples showing the correspondence with the specific configurations and the like described in the embodiments described later, and the present disclosure is limited to the specific configurations and the like shown in the symbols in the parentheses. It's not something.

FIG. 1 is a flowchart showing a method of analyzing the resultant force in the embodiment. FIG. 2 is a schematic diagram showing the distribution of the reaction force calculated by the method of analyzing the resultant force of FIG. FIG. 3 is a schematic diagram showing the output result of the action line of the resultant force in the method of analyzing the resultant force of FIG. FIG. 4A is a schematic diagram showing the output result of the action line of the resultant force in the method of analyzing the resultant force of FIG. 1, and FIG. 4B is a schematic diagram showing an example of the evaluation of stability. FIG. 5 is a flowchart showing a method of displaying arrows in the output process of FIG.

Hereinafter, embodiments to which the present disclosure has been applied will be described with reference to the drawings.
[1. First Embodiment]
[1-1. Constitution]
The method of analyzing the resultant force shown in FIG. 1 is a method of three-dimensionally analyzing the resultant force of the reaction force received by the human body or the doll from the object when a load is applied to the elastic object by the human body or a doll imitating the human body. Is. In the present embodiment, the human body or the doll is treated as a rigid body or a deformed body.

As shown in FIG. 1, the method of analyzing the resultant force of the present embodiment includes a calculation step S10, a reaction force distribution calculation step S20, a resultant force calculation step S30, an action line calculation step S40, a center of gravity calculation step S50, and an output. A step S60 and a stability evaluation step S70 are provided.

<Calculation process>
In this step, as shown in FIG. 2, a three-dimensional model in which the human body 20 is in contact with the elastic object 10 from above in the vertical direction is created, and the deformation amount, load, etc. of the object 10 are created by the finite element method (FEM). To calculate.

Examples of the object 10 include a flexible sheet used for a vehicle or a building. In the present embodiment, the human body 20 is seated from above the object 10, and a load due to the weight of the human body 20 is applied to the object 10.

<Reaction force distribution calculation process>
In this step, from the analysis result of FEM obtained in the calculation step S10, the distribution of the reaction force r that the human body 20 receives from the object 10 on the contact surface between the object 10 and the human body 20 shown in FIG. 2 in the three-dimensional space is obtained. Ask.

In the present embodiment, the reaction force r is decomposed into two or more component forces to obtain the distribution for each component force. Specifically, the reaction force r is decomposed into a normal force and a frictional force. The normal force is a component force in the normal direction of the contact surface between the object 10 and the human body 20. The frictional force is a component force in a direction parallel to the contact surface between the object 10 and the human body 20. That is, the direction of the normal force and the direction of the frictional force are orthogonal to each other.

<Coupling force calculation process>
In this step, the resultant force obtained by synthesizing the distribution of reaction forces is obtained. Specifically, the vectors of the distributed component forces (that is, the load) are summed for each component force of the reaction force (normal force and frictional force in this embodiment). As a result, the resultant force for each component force is required.

For example, with the component force r1 of the load f1 (u ₁ , v ₁ , w _{1 ) = (1, 3, 2) existing at the point A1 (x 1} , y ₁ , z _{1) = (2, 4, 2).} , The component force r2 of the load f2 (u ₂ , v ₂ , w ₂ ) = (-2, 4, 1) existing at the point A2 (x ₂ , y ₂ , z _{2) = (8, 2, 4)} The resultant force (u ₀ , v ₀ , w ₀ ) is (1-2, 3 + 4, 2 + 1) = (-1, 7, 3).

<Action line calculation process>
In this step, the action line of the resultant force obtained in the resultant force calculation step S30 is obtained by using the balance of the moments in the human body 20.

Specifically, the coordinates of the points on the action line of the resultant force are (x, y, z), the moment around the Z axis at the action point of each component force rn is M _z n, and the moment around the X axis is M _x n. , when the moment around the Y axis and the M _{y n,} the relationship moments are balanced around the Z axis, the relationship moments are balanced about the X axis, and relationships that moment are balanced about the Y-axis, the following formulas (1-1 ), (2-1) and (3-1). The straight line that satisfies this cubic system of equations is the line of action of the resultant force.

v ₀・ x−u ₀・ y = ΣM _z n ・ ・ ・ (1-1)
w ₀・ y−v ₀・ z = ΣM _x n ・ ・ ・ (2-1)
u ₀・ z−w ₀・ x ＝ ΣM _x n ・ ・ ・ (3-1)
For example, in the case of the above-mentioned component forces r1 and r2, the moment around the Z axis in the action line of these resultant forces is u ₀ · x−v ₀ · y = 7x− (−y) = 7x + y. On the other hand, the sum of the moments around the Z axis at points A1 and A2 is M _z 1 + M _z 2 = (v ₁ · x ₁ −u ₁ · y ₁ ) + (v ₂ · x ₂ −u ₂ · y ₂ ) = It becomes 3,2-1,4 + 4.8- (-2), 2 = 38. Similarly, the sum of the moments around the X axis at points A1 and A2 is -12, and the sum of the moments around the Y axis is 18. Therefore, the line of action of the resultant force is the simultaneous equations {(x-4) / (-1)} = {(y-10) / of the following equations (1-2), (2-2) and (3-2). It is calculated as 7} = {(z-6) / 3}.

7x + y-38 = 0 ... (1-2)
3y-7z + 12 = 0 ... (2-2)
3x + z-18 = 0 ... (3-2)
<Center of gravity calculation process>
This step is a step performed in parallel with the reaction force distribution calculation step S20, the resultant force calculation step S30, and the action line calculation step S40. In this step, the center of gravity G of the human body 20 shown in FIG. 2 is obtained from the analysis result of FEM obtained in the calculation step S10.

<Output process>
In this step, as shown in FIGS. 3 and 4A, the action line L1 of the resultant force obtained in the action line calculation step S40 is output. Further, in this step, the center of gravity G of the human body 20 obtained in the center of gravity calculation step S50 is output. Specifically, the action line L1 and the center of gravity G are superimposed and output on the analysis result of the FEM used in the calculations so far.

In this step, for example, the action line L1 may be displayed for each of the normal force and the frictional force, which are the component forces of the reaction force, or these may be displayed in an overlapping manner. Note that FIG. 3 shows a state in which the action line L1 overlaps with the vertical line L2 passing through the center of gravity G, and FIG. 4A shows a state in which the action line L1 and the vertical line L2 are deviated from each other.

Further, in this step, an arrow R indicating the magnitude and direction of the resultant force is displayed on the action line L1. As shown in FIG. 5, the method for displaying the arrow R includes a plane calculation step S61, an intersection calculation step S62, an arrow assumption step S63, and an arrow display step S64.

(Plane calculation process)
In this step, a virtual plane that passes through the center of gravity G and has the direction vector of the action line L1 as the normal vector is obtained.

(Intersection calculation process)
In this step, the coordinates of the intersection P of the virtual plane and the action line L1 obtained in the plane calculation step S61 are obtained.

(Arrow assumption process)
In this step, the thickness and length of the arrow R are assumed. The thickness and length of the arrow R can be appropriately set according to the magnitude of the resultant force. For example, the thickness may be constant (for example, 20 mm), and the length may be determined to be 1 mm per 1 N of resultant force. The direction of the arrow R is the same as the direction vector of the action line L1.

(Arrow display process)
In this step, the arrow R assumed in the arrow assumption step S63 is drawn starting from the intersection P obtained in the intersection calculation step S62.

<Stability evaluation process>
In this step, the stability of the human body 20 is evaluated based on the positional relationship between the action line L1, the center of gravity G, and the arrow R output in the output step S60.

For example, as shown in FIG. 3, when the action line L1 overlaps with the vertical line L2 passing through the center of gravity G, it can be evaluated that the stability of the human body 20 is good and the sitting comfort or riding comfort is good. On the other hand, when the action line L1 and the vertical line L2 are deviated from each other as shown in FIG. 4A, it can be evaluated that the human body 20 is easily rotated and the stability is poor as shown in FIG. 4B.

[1-3. effect]
According to the embodiment described in detail above, the following effects can be obtained.
(1a) Since the resultant force is obtained from the distribution of the reaction force and the action line L1 of the resultant force is output, the stability of the human body 20 can be visually evaluated by the visualized action line L1. Further, since the work line of the resultant force can be output in consideration of the frictional force, the behavior of the human body 20 can be evaluated more realistically.

(1b) By outputting the center of gravity G of the human body 20 in addition to the action line L1 of the resultant force, the positional relationship between the center of gravity G of the human body 20 and the action line L1 of the resultant force can be grasped, so that the behavior of the human body 20 can be grasped more effectively. Can be evaluated.

(1c) By finding the resultant force for each component force obtained by decomposing the reaction force, the reaction force can be decomposed into component forces in any direction and visualized, so that the optimum evaluation is made according to the shape and usage conditions of the object 10. Is possible.

(1d) By decomposing the reaction force into two components, the normal force and the frictional force, and obtaining the respective resultant forces, for example, the behavior due to the reaction force with respect to the human body 20 seated on the seat can be evaluated more accurately.

(1e) By outputting the action line L1 of the resultant force on the analysis result of the finite element method, it is possible to perform from the calculation for obtaining the resultant force to the confirmation of the output result of the action line L1 of the resultant force on the same screen. Therefore, workability is improved.

(1f) Since the behavior of the human body 20 is evaluated based on the action line L1, the center of gravity G, and the arrow R of the output resultant force, the stability of the human body 20 on the object 10 is evaluated more easily and accurately than before. Can be done.

[2. Other embodiments]
Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take various forms.

(2a) In the method of analyzing the resultant force of the above embodiment, a doll imitating a human body (so-called mannequin) may be used instead of the human body. The present disclosure can also be applied to evaluate the behavior of a doll.

(2b) The method of analyzing the resultant force of the above embodiment may target a state in which a plurality of human bodies or dolls are in contact with one object 10. In this case, the resultant force of the reaction force can be obtained for each human body or the doll, and the total resultant force can be obtained by further synthesizing the resultant force. Further, as for the center of gravity of the human body or the doll, the center of gravity obtained by combining the respective centers of gravity can be treated as the entire center of gravity.

(2c) In the method of analyzing the resultant force of the above embodiment, for example, a human body or a doll may be modeled by a deformed body in which a plurality of rigid bodies corresponding to each part of the human body are connected by a joint. In addition, when evaluating the stability of a part of the deforming human body (for example, only the head), in addition to the resultant force of the reaction force received from the object, the force acting on the boundary surface of a part of the human body and its Stability may be evaluated using the moment due to force.

(2d) In the method of analyzing the resultant force of the above embodiment, it is not always necessary to calculate and output the center of gravity. Also, when calculating and outputting the center of gravity, it is not always necessary to display it on top of the action line of the resultant force.

(2e) In the method of analyzing the resultant force of the above embodiment, it is not always necessary to decompose the reaction force into two or more component forces. Further, when the reaction force is decomposed into a component force, it is not always necessary to decompose the reaction force into a normal force and a frictional force.

(2f) In the method of analyzing the resultant force of the above embodiment, the action line of the resultant force and the center of gravity of the human body or the doll do not necessarily have to be output on the analysis result of FEM. That is, the action line and the center of gravity of the resultant force may be displayed on a screen or the like different from the FEM analysis result.

(2g) In the method of analyzing the resultant force of the above embodiment, the stability evaluation step is not an essential configuration. Therefore, an evaluation other than the stability of the human body or the doll may be performed based on the action line of the output resultant force.

(2h) The method of analyzing the resultant force of the above embodiment can also be applied to a two-dimensional analysis. For example, it is possible to analyze the resultant force in the reaction force acting on the foot of the human body with the object 10 as the sole of the shoe as the object of analysis.

(2i) The functions of one component in the above embodiment may be dispersed as a plurality of components, or the functions of the plurality of components may be integrated into one component. Further, a part of the configuration of the above embodiment may be omitted. Further, at least a part of the configuration of the above embodiment may be added or replaced with the configuration of the other embodiment. It should be noted that all aspects included in the technical idea specified from the wording described in the claims are embodiments of the present disclosure.

10 ... an object, 20 ... a human body.

Claims (5)

A method of analyzing the resultant force of the reaction force that the human body or the doll receives from the object when a load by a human body or a doll that imitates the human body is applied to an elastic object by using an information processing device. ,
The information processing device
A step of obtaining the distribution of the reaction force received by the human body or the doll from the object on the contact surface between the object and the human body or the doll.
The process of obtaining the resultant force by synthesizing the distribution of the reaction force and
The step of obtaining the action line of the resultant force by using the balance of the moments in the human body or the doll, and
The process of outputting the action line of the resultant force and
The process of finding the center of gravity of the human body or the doll,
The step of evaluating that the smaller the deviation between the line of action of the resultant force and the vertical line passing through the center of gravity, the higher the stability.
The execution, analysis method of the resultant force. The method for analyzing the resultant force according to claim 1.
In the output step, a method for analyzing a resultant force that outputs the center of gravity of the human body or the doll. The method for analyzing the resultant force according to claim 1 or 2.
In the step of obtaining the distribution of the reaction force, the distribution of each component force is obtained by decomposing the reaction force into two or more component forces.
In the step of obtaining the resultant force, an analysis method of the resultant force for obtaining the resultant force for each component force. The method for analyzing the resultant force according to claim 3.
A method for analyzing a resultant force, wherein the two or more component forces are a normal force and a frictional force. The method for analyzing a resultant force according to any one of claims 1 to 4.
In the step of obtaining the distribution of the reaction force, the reaction force is obtained by the finite element method.
In the output step, a method of analyzing the resultant force, which outputs the action line of the resultant force on the analysis result of the finite element method.

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