Dynamic followability evaluation device and dynamic followability evaluation method

Abstract

To provide a device and method capable of objectively and reproducibly evaluating the dynamic followability of an elastic body such as a mattress or cushion.SOLUTION: A dynamic followability evaluation device S is a device that evaluates the dynamic followability of an evaluation object 5 having elasticity, and comprises: pressing means 1 that presses and deforms the evaluation object 5; a load cell 2 that measures the pressing force applied to the evaluation object 5 by the pressing means 1; a displacement sensor 3 that measures the amount of deformation of the evaluation object 5 caused by the pressing; and control means 4 that controls the pressing force of the pressing means 1. After deforming the evaluation object 5 by a predetermined amount, the control means 4 controls the pressing force of the pressing means 1 so that the deformation amount is maintained, and evaluates the dynamic followability of the evaluation object 5 based on temporal changes in the pressing force.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an apparatus and method for evaluating the dynamic tracking capability of an elastic object to be evaluated. [Background technology]

[0002] The dynamic conformance of elastic bodies such as mattresses and cushions is a very important characteristic in terms of how well they can follow the movements of the user, that is, how closely they can fit to the user's body when the user moves.

[0003] For example, as shown in Figure 4(a), in a mattress 91 made of urethane or the like, when object A placed on the top surface of the mattress 91 moves upward, the recessed portions of the mattress 91 do not restore to their original state to keep up with the upward movement of object A, and a gap may form between the bottom surface of object A and the top surface of the mattress 91. On the other hand, as shown in Figure 4(b), in a mattress 92 made of a three-dimensional mesh structure or the like, the recessed portions of the mattress 92 restore to their original state to keep up with the upward movement of object A, and no gap forms between the bottom surface of object A and the top surface of the mattress 92, resulting in a tight fit. Such differences in the dynamic compliance of mattresses affect characteristics such as the ability to turn over in bed and sit up.

[0004] However, until now, evaluation of the characteristics of elastic bodies such as mattresses has been done by measuring the resilience when compressed to a certain thickness (the hardness of the elastic body) or the height to which a steel ball bounces back after being dropped from a certain height onto the elastic body (the resilience of the elastic body). However, dynamic tracking ability, or how well the body can follow the movements of the user, has relied solely on sensory evaluation by the subject. Summary of the Invention [Problem to be solved by the invention]

[0005] However, sensory evaluation by subjects is prone to variations in evaluation results from subject to subject, and there is also the problem that the reproducibility of the evaluation cannot be guaranteed.

[0006] Therefore, an object of the present invention is to provide an apparatus and method that can objectively and reproducibly evaluate how well an elastic body such as a mattress or cushion can follow the movements of a user (dynamic followability). [Means for solving the problem]

[0007] In order to achieve the above object, a dynamic tracking evaluation device according to one embodiment of the present invention is a device for evaluating the dynamic tracking of an elastic object to be evaluated, and is equipped with a pressing means for pressing and deforming the object to be evaluated, a first measuring means for measuring the pressing force applied to the object to be evaluated by the pressing means, a second measuring means for measuring the amount of deformation of the object to be evaluated due to the pressing, and a control means for controlling the pressing force of the pressing means, wherein after the object to be evaluated has been deformed by a predetermined amount, the control means controls the pressing force of the pressing means so that the amount of deformation is maintained, and the dynamic tracking of the object to be evaluated is evaluated from the change in the pressing force over time.

[0008] It is preferable that the evaluation device having the above configuration further comprises a storage means for storing the change over time of the pressing force measured by the first measurement means.

[0009] Furthermore, a dynamic tracking evaluation method according to one aspect of the present invention that achieves the above-mentioned object is a method for evaluating the dynamic tracking of an elastic object to be evaluated, which is characterized in that after pressing the object to be evaluated to deform it a predetermined amount, the pressing force is controlled so that the amount of deformation is maintained, and the dynamic tracking of the object to be evaluated is evaluated from the change in pressing force over time.

[0010] In the evaluation method having the above configuration, the change in the pressure force over time may be subjected to a fast Fourier transform to obtain a frequency spectrum, and the dynamic tracking ability of the evaluation object may be evaluated using the intensity at a predetermined frequency as an index. [Effects of the Invention]

[0011] The dynamic tracking evaluation device and evaluation method according to the present invention make it possible to objectively and reproducibly evaluate the dynamic tracking of an elastic object to be evaluated, which has previously been evaluated by sensory testing by subjects. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram illustrating an embodiment of an evaluation device according to the present invention. [Figure 2] 10 is a graph showing an example of the change over time in the measured values ​​of the pressing pressure and pressing displacement of the pressing part, measured using a mattress made of a three-dimensional network structure as the evaluation object. [Figure 3] 10 is a graph showing an example of the change over time in the measured values ​​of the pressing pressure and pressing displacement of the pressing part, measured using a mattress made of urethane as the evaluation object. [Figure 4] 10A and 10B are diagrams illustrating the dynamic followability of an elastic body. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the dynamic tracking performance evaluation device and evaluation method according to the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.

[0014] Fig. 1 is a schematic diagram showing one embodiment of an evaluation device according to the present invention. The evaluation device S shown in Fig. 1 includes a pressing means 1 that presses and deforms an evaluation object 5, a load cell (first measuring means) 2 that measures the pressing force applied to the evaluation object 5 by the pressing means 1, a displacement sensor (second measuring means) 3 that measures the amount of deformation of the evaluation object 5 due to the pressing, a control means 4 that controls the pressing force of the pressing means 1, and a personal computer PC.

[0015] The pressing means 1 includes a base 11, a pair of support columns 12a, 12b attached to the upper surface of the base 11 perpendicular to the upper surface and spaced apart horizontally, an upper frame body 13 having a pair of through holes 131a, 131b through which the pair of support columns 12a, 12b can be inserted, and which is provided so as to be movable in the vertical direction on the pair of support columns 12a, 12b by inserting the support columns 12a, 12b into the through holes 131a, 131b, a hydraulic cylinder 14 fixed to the upper frame body 13, and a hydraulic unit 15 which supplies oil to the hydraulic cylinder 14 to move a piston rod 141 in and out.

[0016] The hydraulic cylinder 14 is attached to the upper frame 13 so that the piston rod 141 moves in and out perpendicularly to the top surface of the base 11. A truncated cone-shaped pressing unit 16 is attached to the tip of the piston rod 141. The pressing unit 16 contacts the object 5 and presses it with a desired pressure and a desired amount, deforming the object 5. The bottom shape of the pressing unit 16 is not particularly limited, but in this embodiment it is circular with a diameter of 150 mm. The pressing unit 16 can be replaced with an object of any desired shape. The pressing pressure (pressing force), pressing displacement (deformation amount), pressing speed, etc. of the pressing unit 16 are controlled by controlling the oil supply from the hydraulic unit 15 to the hydraulic cylinder 14 using control signals sent from the control means 4 to the hydraulic unit 15. The pressing pressure and pressing displacement can be appropriately determined based on the size and material of the object 5. In this embodiment, the pressing pressure can be set up to 1000 N, and the pressing displacement can be set up to several tens of mm.

[0017] The load cell 2 is attached to the upper surface of the base 11 so that the axis of the load button 21 and the axis of the piston rod 141 of the hydraulic cylinder 14 are on the same axis L1. A mounting table 22 on which the object to be evaluated 5 is placed is fixed to the upper end surface of the load button 21. The shape and size of the mounting table 22 are determined appropriately depending on the shape, etc. of the object to be evaluated 5. A measurement signal from the load cell 2 is sent to the control means 4.

[0018] The displacement sensor 3 is attached near the piston rod 141 of the hydraulic cylinder 14, and measures the extrusion distance (deformation amount) of the piston rod 141. A measurement signal from the displacement sensor 3 is sent to the control means 4.

[0019] The control means 4 controls the amount of oil supplied from the hydraulic unit 15 to the hydraulic cylinder 14, thereby controlling the extrusion pressure (pressing force), extrusion distance (deformation amount) and extrusion speed of the pressing part 16.

[0020] The personal computer PC is connected to the control means 4. The personal computer PC serves as a setting input unit for inputting control setting values ​​for the pressing means 1, a memory unit for storing changes in measurement data over time, an arithmetic processing unit for processing the measurement data, a display unit for displaying the measurement data, etc.

[0021] (Evaluation Procedure) The object to be evaluated 5 is placed on the mounting table 22. There are no particular limitations on the size or shape of the object to be evaluated 5, but it is generally preferable that the shape of the object to be evaluated 5 be a rectangular parallelepiped. In the device of this embodiment, the object to be evaluated 5 is a rectangular parallelepiped measuring 300 mm x 300 mm x 200 mm. Next, the upper frame 13 of the pressing means 1 is moved downward along the pair of support columns 12a, 12b so that the lower surface of the pressing portion 16 contacts or is close to the upper surface of the object to be evaluated 5. Then, at that position, the upper frame 13 is fixed to the pair of support columns 12a, 12b so that it cannot move.

[0022] Next, the hydraulic unit 15 is started, and the pressing part 16 is pressed into the evaluation object 5 with a predetermined pressure to a predetermined displacement. After the pressing part 16 is pressed to the predetermined displacement, the pressing pressure is controlled by the control means 4 so that the pressing part 16 maintains that displacement. During this time, the pressing pressure is measured by the load cell 2, and the pressing displacement is measured by the displacement sensor 3.

[0023] (Measurement value evaluation) The indentation pressure measured by the load cell 2 and the indentation displacement measured by the displacement sensor 3 are sent to a personal computer PC via the control means 4 and stored in a memory unit. Figure 2 shows an example of the change over time in the measured indentation pressure and indentation displacement of the pressing unit 16, measured on an evaluation object 5, a mattress composed of a three-dimensional network structure. In Figure 2, the horizontal axis represents time (s) and the vertical axis represents indentation pressure (N) and indentation displacement (mm), showing the change over time in indentation pressure and indentation displacement. In Figure 2, the solid line represents indentation pressure and the dashed line represents indentation displacement.

[0024] As can be seen from Figure 2, one second after the start of measurement, the pressing part 16 was pressed into the evaluation object 5 with a pressure of 150 N to a displacement of 10 mm, and then the pressing pressure was controlled to maintain a pressing displacement of 10 mm until two seconds after the start of measurement. As a result, although the pressing pressure fluctuated initially, it remained stable at approximately 140 N after 1.2 seconds after the start of measurement. In other words, while the pressing part 16 was pressed into the evaluation object 5, it continued to maintain a stable repulsive force of approximately 140 N. In other words, in the case of a mattress composed of a three-dimensional mesh structure, when the user turns over or gets up, the mattress follows the user's movements, and it is evaluated that there is no gap between the mattress surface and the user's body, resulting in a tight fit.

[0025] Figure 3 shows the results of measuring a urethane mattress as the evaluation object 5. One second after the start of measurement, the pressing part 16 was pressed into the evaluation object with a pressure of 150 N to a displacement of 4 mm, and then the pressing pressure was controlled so that the pressing displacement of 4 mm was maintained until two seconds after the start of measurement. The horizontal and vertical axes in Figure 3 are the same as those in Figure 2.

[0026] As can be seen from Figure 3, the compression pressure momentarily reached 150 N at the beginning of compression, then immediately dropped to about 10 N, and after fluctuating for a short period of time, maintained at about 10 N. In other words, in the case of a mattress made of urethane, when the user turns over or gets up, the mattress cannot adequately follow the user's movements, and a gap may form between the mattress surface and the user's body.

[0027] In addition, the measured change in indentation pressure over time can be measured using a differential circuit to block low-frequency vibrations, followed by a fast Fourier transform to obtain a frequency spectrum, and the intensity at a specified frequency can be used as an index to evaluate the dynamic tracking ability of the object being evaluated in more detail.

[0028] For example, by investigating in advance the correlation between the intensity value of a specific frequency in the frequency spectrum and the sense of speed of the mattress's conformance felt by the user, it may be possible to evaluate differences in the quality of conformance. Specifically, in the graph of Figure 2, the fluctuations in the compression pressure from 1 second to 1.2 seconds after the start of measurement are subjected to a fast Fourier transform to obtain the frequency spectrum, and the sense of speed of conformance can be evaluated from the intensity value of the frequency that shows the maximum value in the frequency spectrum.

[0029] (Other variations) Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Addition, omission, substitution, and other modifications of the configuration are possible within the scope of the spirit of the present invention. The present invention is not limited by the above description, but is limited only by the scope of the appended claims. [Industrial Applicability]

[0030] The evaluation device and evaluation method according to the present invention are useful in that they enable objective and reproducible evaluation of the dynamic tracking ability of an elastic object to be evaluated, which has previously been evaluated by sensory testing by subjects. [Explanation of symbols]

[0031] S Dynamic tracking evaluation device 1 Pressing means 2. Load cell (first measuring means) 3. Displacement sensor (second measuring means) 4. Control Measures PC Personal computer (storage means)

Claims

1. An apparatus for evaluating the dynamic tracking ability of an elastic object to be evaluated, a pressing means for pressing and deforming the object to be evaluated; a first measuring means for measuring a pressing force applied to the object to be evaluated by the pressing means; A second measuring means for measuring the deformation amount of the evaluation object due to pressing; a control means for controlling the pressing force of the pressing means; Equipped with A dynamic tracking evaluation device characterized in that after the object to be evaluated is deformed by a predetermined amount, the control means controls the pressing force of the pressing means so that the amount of deformation is maintained, and the dynamic tracking ability of the object to be evaluated is evaluated from the change in the pressing force over time.

2. 2. The dynamic tracking evaluation device according to claim 1, further comprising a storage means for storing the change over time of the pressing force measured by the first measuring means.

3. A method for evaluating the dynamic tracking ability of an elastic object to be evaluated, comprising: A dynamic tracking evaluation method characterized by pressing an object to be evaluated to deform it a predetermined amount, then controlling the pressing force so that the amount of deformation is maintained, and evaluating the dynamic tracking ability of the object to be evaluated from the change in pressing force over time.

4. 4. The dynamic tracking evaluation method according to claim 3, wherein the time-dependent change in the pressure is subjected to a fast Fourier transform to obtain a frequency spectrum, and the dynamic tracking ability of the object to be evaluated is evaluated using the intensity at a predetermined frequency as an index.

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