JP2011045566A - Method of estimating physical burden of action to pour out liquid from container, and method for manufacturing container body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable it to objectively and quantitatively evaluate the physical burden of a series of actions of lifting a container body and then tilting it to pour out liquid from it. <P>SOLUTION: The method of estimating the burden of an action to pour out liquid from a container includes a step to obtain the information on myoelectric potential at the maximum voluntary isometric shrinkage of the acting muscles related to the feeling of burden when a series of actions are made to hold and lift a container body and then tilt it, a step to obtain the information on myoelectric potential of the acting muscles when their liquid pouring-out action is made, and a step to calculate the maximum muscle power ratio, i.e., a number 1: maximum muscle power ratio=the myoelectric potential for the action to pour out liquid from the container/the myoelectric potential of muscles at the maximum voluntary isometric shrinkage. A quantitative evaluation is made on the burden of the action to pour out liquid from a container, based on this maximum muscle power ratio. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention quantitatively determines the degree of burden on consumers during this operation for all containers that involve a series of operations (hereinafter also referred to as pouring operations) for grasping and lifting the container body and subsequently tilting the container body. The present invention relates to a technique for evaluating and estimating how much a consumer feels as a subjectivity and a method for manufacturing a container body using the technique.

  Conventionally, the method of evaluating the container is sensory evaluation, and the prototype and the conventional product developed by many subjects are poured out, and the feeling of use is scored in 5 to 7 stages. They were aggregated and evaluated relatively.

  By the way, there is a disclosure of a technique for measuring a myoelectric potential of a skeletal muscle with respect to a container opening performance and evaluating a burden in a container opening operation (see, for example, Patent Document 1). According to the technique of Patent Document 1, the openability of a container can be objectively and quantitatively evaluated.

  Similarly, there is a disclosure of a technique for measuring muscle strain (see, for example, Patent Documents 2 to 4).

JP 2009-56040 A JP 2004-275214 A JP 2006-75200 A JP 2004-344356 A

  According to the method for evaluating the openability of a container disclosed in Patent Document 1, although the openability can be objectively and quantitatively evaluated, the ease of pouring of PET bottles, which have been widely used in recent years, is evaluated. Can not. The number of plastic bottles that emphasizes various functional designs is increasing, but there are also complaints about usability. For example, the container is soft and is likely to be dropped when it is held, it is difficult to hold without a dent or a part that gets caught on a finger, it is difficult to hold with one hand, and it is easy to spill. In particular, the case of a large PET bottle of 1.5 to 2 liter size is remarkable.

  However, if sensory evaluation is performed on the ease of pouring of PET bottles, many subjects must be collected and evaluated, which takes time and effort. Therefore, sensory evaluation takes too much time during the development stage, so it is difficult to carry out each trial production. Moreover, in the case of sensory evaluation, it is difficult to obtain an objective and quantitative result.

  The “easy to do” in the pouring operation varies depending on the shape and dimensions (hereinafter referred to as design elements) of the container gripping part, but it is not clear which design element is bad by the conventional interview and questionnaire survey methods. Therefore, it is difficult to clarify the direction of improving the shape of the container.

  Therefore, an object of the present invention is to make it possible to objectively and quantitatively evaluate the physical burden in a series of pouring operations in which the container body is lifted and then the container body is tilted. This makes it possible to estimate how the consumer actually evaluates the developed product subjectively.

The present inventors have identified a working muscle that works during the operation of a container with a pouring operation, and established a method for evaluating the burden of the container pouring operation using the myoelectric potential of the working muscle. did. That is, the method for estimating the load of the container pouring operation according to the present invention is an operation line related to a sense of burden when a series of pouring operations are performed by grasping and lifting the trunk of the container body and subsequently tilting the container body. A step of acquiring myoelectric potential information at the time of the maximum voluntary isometric contraction, a step of acquiring myoelectric potential information of the operating muscle when the pouring operation is performed, and a maximum muscle strength ratio represented by Formula 1 And calculating a burden in the pouring operation based on the value of the maximum muscle strength ratio.
(Equation 1) Maximum muscle strength ratio = Myoelectric potential during pouring / Maximum voluntary isometric contraction

  In the container pouring operation load estimation method according to the present invention, the myoelectric potential information of the operating muscles includes the myoelectric potential information when gripping and lifting the torso of the container body and the muscles when the container body is tilted. It is preferable to obtain it separately from potential information. The burden feeling in the pouring operation can be analyzed for each operation.

  In the container pouring operation load estimation method according to the present invention, the operation muscle related to the sense of burden is a first dorsal interosseous muscle, a long thumb abductor muscle as an operation muscle for evaluating the lifting operation, The first dorsal interosseous muscle or the total finger extensor muscle includes at least one kind selected from the total finger extensor and the lateral carpal extensor, and is used as an action muscle for evaluating the action of tilting the container body. It is preferable to include any one kind and superficial flexor muscle. It is possible to select the minimum necessary muscles and evaluate them easily.

  In the container pouring operation load estimation method according to the present invention, the operation muscles related to the sense of burden are the first dorsal interosseous muscle, the long thumb abductor, the total finger extensor, the heel side carpal extensor, and It is preferable to include a superficial digit flexor. Detailed evaluation and analysis can be performed by obtaining information on the motion lines related to the pouring operation.

  The container body manufacturing method according to the present invention is obtained by the container pouring operation load estimation method according to the present invention, and the body shape of the container body so that the maximum muscle strength ratio in the pouring operation satisfies 0.5 or less. It is characterized by having decided. By using the evaluation result obtained by the method for estimating the load of the container pouring operation according to the present invention, it is possible to manufacture a container body that is easy to pour out.

  According to the present invention, it is possible to objectively and quantitatively evaluate the physical burden in the pouring operation. This makes it possible to estimate how the consumer actually evaluates the developed product subjectively. At this time, there is no need to collect a large number of subjects as in the sensory evaluation, and a series of sufficient pours can be obtained even from the measurement results of a specific number of subjects with different physical characteristics (man and woman, hand size, etc.). It is possible to objectively and quantitatively evaluate the physical burden in motion. In addition, since time-consuming sensory evaluation is not required, the time required for evaluation can be shortened. In addition, by selecting people who are located at the boundary of the subject population, such as people with large hands, small people, people with large grip strength, small people, etc. in the population, taking data of these people, The container most suitable for the population can be estimated. Furthermore, since a large line of burden is clarified, it becomes easy to specify a design element causing the burden, and the direction of shape improvement can be clarified logically.

This is a classification of the action poured into the cup, and is divided into four kinds of actions of types 1 to 4. It is a figure which shows the name and position of each muscle. The relationship between the maximum muscle strength ratio of the superficial flexor muscle and the subjective evaluation of the subject on the muscle load was shown. It is a figure which shows the specific reference | standard of the numerical value of the test subject's subjective evaluation of the vertical axis | shaft in FIG. The result of subjective evaluation in Example 1 is shown. The maximum muscle strength ratio (% MVC) in the lifting operation is shown. The maximum muscle strength ratio (% MVC) in the pouring operation was shown. It is a figure which shows the shape of the 2 liter bottle used in Example 2, (a) is a front view of an A type bottle, (b) is an AA broken sectional view of an A type bottle, (c) is a B type bottle (D) is an AA broken sectional view of a B-type bottle. The result of the subjective evaluation in the lifting operation that averaged the data of 6 subjects was shown. The result of the subjective evaluation in the pouring operation that averaged the data of 6 subjects was shown. The maximum muscular strength ratio (% MVC) in the lifting motion that averaged the data of six subjects was shown. The maximum muscular strength ratio (% MVC) in the pouring motion that averaged the data of 6 subjects was shown. The result of the subjective evaluation in the lifting movement of the subject with weak grip is shown. The result of the subjective evaluation in the pouring motion of the subject with weak grip is shown. The maximum muscular strength ratio (% MVC) in the lifting motion of the subject with weak grip strength was shown. Maximum muscle strength ratio (% MVC) was shown in the pouring action of subjects with weak grip strength

  Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not construed as being limited to these descriptions. As long as the effect of the present invention is exhibited, the embodiment may be variously modified.

(Identification of movement muscle)
First, the measurement object prepared the main body of the container (pet bottle) made from 2 liter polyethylene terephthalate. Next, 11 men and women in their 20s were asked to pour them freely into the cup without instructing them to observe them. It was as follows when the pouring operation was seen by the movement of each joint of the upper limb.
(1) Hold. That is, the movement of bending of the thumb, adduction, and bending of the second to fifth fingers.
(2) Lift up. That is, elbow joint flexion, wrist joint flexion, extension movement.
(3) Pour into a cup. This operation was divided into four types of operations of types 1 to 4 as shown in FIG.

  The muscle which can measure an electromyogram was selected among the action | operation muscles which work in the operation | movement of said (1)-(3). The results are shown in Table 1. As the skeletal muscles of the hands and arms, there are the muscles shown in Fig. 2 (Source: Mori, Ogawa et al., Supervised by Kanbara: Shared Anatomy 1 Review / Boneology / Humanology / Mythology, Kanehara Publishing Co., Ltd., 1982) .

  The electromyogram is a graph in which the elapsed time of the myoelectric potential is on the horizontal axis and the myoelectric potential is on the vertical axis. Muscles contract in response to commands from the brain, but these commands are transmitted as electrical signals. The electric signal measured by an electrode fixed on the skin surface is called myoelectric potential. Myoelectric potential is not only a measurement system but also has large individual differences such as muscle mass, skin thickness, and the appearance of muscle activity with respect to load. Therefore, it is also referred to as “maximum voluntary contraction” (hereinafter referred to as “MVC: maximum voluntary contraction”). ) When using a relative value (% MVC) where the myoelectric potential at time is 100%, errors such as individual differences can be reduced.

  Next, a method for estimating the burden of the container pouring operation according to this embodiment will be described. The container pouring operation load estimation method according to the present embodiment includes at least three steps, that is, a first step: a step of acquiring myoelectric potential information during the maximum voluntary isometric contraction of the moving muscle, and a second step: Myoelectric potential information acquisition step, third step: maximum muscle strength ratio calculation step. Hereinafter, it demonstrates in order.

(Acquisition process of EMG information during maximum voluntary isometric contraction of moving muscle)
The myoelectric potential at the time of maximum voluntary isometric contraction was determined for each of the moving muscles shown in Table 1. The myoelectric potential is measured by a known method using an electromyograph, for example, by attaching an electrode to a muscle part of the hand / arm and measuring the myoelectric potential.

(Acquisition process of action muscle EMG information)
Next, the myoelectric potential information of the working muscle when the pouring operation is performed is acquired. The method for measuring the myoelectric potential is the same as that for acquiring myoelectric potential information during the maximum voluntary isometric contraction of the working muscle.

  The motion muscles to be measured when acquiring the myoelectric potential information during the maximum voluntary isometric contraction and the myoelectric potential information during the pouring operation are motion muscles related to the sense of burden during the pouring operation. Specifically, it is the motion line shown in Table 1. Therefore, when performing a simple evaluation, the first dorsal interosseous muscle, the long thumb abductor, the total finger extensor, and the heel side carpal extensor are selected as motion muscles for evaluating the lifting motion. Select at least one type. Then, either the first dorsal interosseous muscle or the total extensor extensor muscle and the superficial digital flexor muscle are selected as the action muscle for evaluating the action of tilting the container body (pouring action). By selecting such operating muscles, when performing the pouring operation, any operating muscle is always measured, and it becomes possible to evaluate the feeling of burden on the subject.

  On the other hand, when the burden feeling of the subject of the pouring operation is evaluated in detail, among the operating muscles shown in Table 1, the first dorsal interosseous muscle, the long thumb abductor, the total finger extensor, the heel side It is preferable to include carpal extensor and superficial flexor muscles. Furthermore, it is more preferable to measure all the moving muscles including the ulnar carpal extensor. It is possible to relatively compare the feeling of burden of each motion muscle.

(Maximum strength ratio calculation process)
As described above, rather than simply comparing myoelectric potentials, in order to eliminate the variation factors of measured values such as individual differences, the relative value (% MVC) with the myoelectric potential at the maximum voluntary isometric contraction as 100% Will be compared. % MVC is the maximum muscle strength ratio, and can be obtained from Equation 1.
(Equation 1) Maximum muscle strength ratio = Myoelectric potential during pouring / Maximum voluntary isometric contraction

  Here, since the myoelectric potential accompanying the pouring operation is measured by drawing an electromyogram, it is preferable to advance the pouring operation with a stationary time between the operations. The specific operation is as follows, for example. Lift for 2 seconds, rest for 3 seconds, tilt for 2 seconds and stop for 3 seconds. For each type of container, the above operation is tried eight times, and the myoelectric potential is converted into the maximum strength ratio and averaged. At this time, the myoelectric potential is full-wave rectified from the myoelectric potential measured for each trial. More specifically, the myoelectric potential data is full-wave rectified. Next, discrete Fourier transform is performed on the raw data measured at 1 kHz. Next, frequency components other than 10 to 250 Hz are cut. Next, inverse Fourier transform is performed. From this result, the myoelectric potential is obtained. Then, the myoelectric potential is divided by the myoelectric potential at the maximum voluntary isometric contraction obtained by the same method, and converted to the maximum muscle strength ratio.

  By passing through the above process, the value of the maximum muscular strength ratio is calculated for each muscle for the container to be measured. Furthermore, by similarly measuring containers having other shapes, the value of the maximum muscle strength ratio is similarly calculated for each muscle. Then, for each container, the maximum muscle strength ratio for each muscle is compared, and the ease of pouring operation of each container is compared and quantified. Since the line with a large burden becomes clear, it becomes easy to identify the design element causing the burden, and the direction of shape improvement can be clarified logically.

  Since the burden estimation method for the container pouring operation according to the present embodiment uses the maximum muscle strength ratio as an index, it is difficult for differences between individuals to occur. Therefore, it is not necessary to collect a large number of subjects as in the sensory evaluation, the body burden in the pouring operation can be objectively evaluated, and it can be expressed quantitatively because it can be expressed by the numerical value of the maximum muscle strength ratio. In addition, if a specific number of subjects with different physical characteristics (men and women, hand size, etc.) are collected and measured as subjects, the body in the pouring operation is assumed assuming subjects who include the physical characteristics. It becomes possible to grasp the burden. By selecting people who are located at the boundaries of the subject population, such as people with large hands, small people, people with large grip strength, and small people in the population, and collecting data on these people, Containers suitable for the population can be estimated.

  The container body can be designed by using the container pouring operation load estimation method according to this embodiment. For example, the trunk shape of the container body is determined so that the maximum muscle strength ratio in the pouring operation obtained by the method for estimating the load of the container pouring operation according to the present invention satisfies 0.5 or less (50% MVC or less). It is the manufacturing method of the container main body.

  The present inventors investigated the relationship between the maximum muscle strength ratio and the subjective evaluation of the subject with respect to the muscle burden (for example, easy, moderately easy, slightly tight, tight, etc.), and can be handled as a logarithmic function. I found out. FIG. 3 shows the relationship between the maximum strength ratio of the superficial digital flexor muscle and the subjective evaluation of the subject with respect to the muscle load. FIG. 4 shows a specific standard (Borg scale) of the numerical value of the subjective evaluation of the subject on the vertical axis in FIG.

  3 and 4, it can be seen that although the magnitude of the value of the myoelectric potential varies among individuals, the subjective evaluation of the subject with respect to the muscle burden is unified regardless of the subject if the maximum muscle strength ratio is used as a reference. Specifically, in the case of superficial digital flexor movement, the subject begins to feel a little strain when the maximum strength ratio exceeds 30%, and the subject feels a tight strain when the maximum strength ratio exceeds 50%. I know I'll start. The same tendency as in FIG. 3 was observed for the other motion muscles. Therefore, if the body shape of the container body is determined so that the maximum muscle strength ratio in the pouring operation satisfies 0.5 or less (50% MVC or less), the subject is less likely to feel a burden. More preferably, the maximum muscle strength ratio is set to 0.3 or less (30% MVC or less). By determining in this way, the container body can be manufactured without undergoing conventional sensory evaluation.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not construed as being limited to the examples.

Example 1
The contact area between the palm and the container body was changed by changing the way of holding, and the relationship between the subject's sense of burden and myoelectric potential in the pouring operation was verified. The subject had a length of 17.0 cm from the boundary between the wrist and palm to the tip of the middle finger.

  The 2 liter PET bottle was grasped so that the center of the height was at the position of the middle finger and the middle finger was directed horizontally, and the pouring operation was performed. This operation is set to 0 °. Next, the same bottle was held so that the center of the height was at the position of the middle finger and the middle finger was directed upward by 15 ° with respect to the horizontal direction, and a pouring operation was performed. This operation is 15 °. Further, the same bottle was grasped so that the center of the height was at the position of the middle finger and the middle finger was directed downward by 15 ° with respect to the horizontal direction, and the pouring operation was performed. This operation is set to -15 °. In order to eliminate the influence of the surface shape of the bottle used, a mock-up with no irregularities was used. One test subject was used.

  The pouring operation is as follows. That is, it lifts in 2 seconds, stops for 3 seconds, tilts in 2 seconds, and stops for 3 seconds. The above operation is tried eight times, and the myoelectric potential is converted into the maximum muscle strength ratio and averaged. At this time, the maximum muscle strength ratio was calculated separately for the lifting operation and the pouring operation. The pouring operation was performed in the type 2 shown in FIG. 1 (however, the gripping is most burdensome). FIG. 5 shows the result of subjective evaluation. FIG. 6 shows the maximum muscle strength ratio (% MVC) in the lifting operation. FIG. 7 shows the maximum muscle strength ratio (% MVC) in the pouring operation. According to FIG. 5, it can be seen that the burden on the subject decreases in the order of −15 °, 0 °, and 15 °. Next, according to FIG. 6, in the lifting operation, the subject feels burdened in the order of −15 °, 0 °, and 15 ° in the three muscles of the first dorsal interosseous muscle, the long thumb abductor and the total finger extensor. It turned out that it has decreased, and it turned out that it corresponds with the subjective evaluation of FIG. Furthermore, according to FIG. 7, in the pouring operation, the subject feels burdened in the order of −15 °, 0 °, and 15 ° in the three muscles of the first dorsal interosseous muscle, the long thumb abductor and the total finger extensor. It turned out that it has decreased, and it turned out that it corresponds with the subjective evaluation of FIG. From the above results, it was found that there is a corresponding relationship between the subjective evaluation and the maximum strength ratio in the pouring operation.

(Example 2)
The test was conducted with 6 men and women with small hands (10s to 30s) as subjects. The length from the boundary between the wrist and the palm to the tip of the middle finger was 15.4 to 17.4 cm, and the grip strength was 18 to 34 kg. The 25th percentile value for adults is 17.4 cm. The bottles used were the 2 liter bottles (hereinafter referred to as A type bottles) shown in FIGS. 8A and 8B and the 2 liter bottles shown in FIGS. 8C and 8D (hereinafter referred to as B type bottles). The pouring operation is as follows. That is, it lifts in 2 seconds, stops for 3 seconds, tilts in 2 seconds, and stops for 3 seconds. The method of tilting was unified to type 2 in FIG. The above operation is tried eight times, and the myoelectric potential is converted into the maximum muscle strength ratio and averaged. At this time, the maximum muscle strength ratio was calculated separately for the lifting operation and the pouring operation.

  FIG. 9 shows the result of subjective evaluation in the lifting operation that averaged the data of six subjects. The result of the subjective evaluation in the pouring operation | movement which averaged the data of six test subjects in FIG. 10 was shown. FIG. 11 shows the maximum muscle strength ratio (% MVC) in the lifting motion that averaged the data of six subjects. FIG. 12 shows the maximum muscle strength ratio (% MVC) in the pouring motion that averaged the data of six subjects. Referring to FIGS. 9 and 10, the B-type bottle has a smaller subjective burden on the subject in any of the operations. In addition, referring to FIGS. 11 and 12, the B-type bottle has a smaller maximum muscle strength ratio in any of the operations. 11 and 12, the muscle A is the first dorsal interosseous muscle, the B muscle is the long thumb abduction muscle, the C muscle is the superficial flexor muscle, the D muscle is the total finger extensor muscle, and the E muscle is the heel side hand. Root extensor muscle. From the above results, it was found that there is a corresponding relationship between the subjective evaluation and the maximum strength ratio in the pouring operation even in a group of subjects with small hands.

  Among the above six subjects, data of subjects with weak grip strength (20s female, hand length 17.2 cm, grip strength 18 kg) are shown in FIGS. FIG. 13 shows the result of subjective evaluation in the lifting operation. FIG. 14 shows the result of subjective evaluation in the pouring operation. FIG. 15 shows the maximum muscle strength ratio (% MVC) in the lifting operation. FIG. 16 shows the maximum muscle strength ratio (% MVC) in the pouring operation. 15 and 16, the muscles A to E are the same as those shown in FIGS. A tendency similar to that shown in FIGS. 9 to 12, that is, a tendency that the B-type bottle has a smaller maximum muscle strength ratio in any of the operations was observed. And it was also found that the difference in muscle burden tends to appear remarkably in the case of a subject with weak grip strength. Therefore, it is possible to easily obtain a significant difference in the quantitative value by measuring the maximum muscle strength ratio of a population (for example, a subject group of lower 25% or less with respect to grip strength) that collects subjects with weak grip strength. As described above, if a person near the boundary of the population is picked up as a subject and the container body has a shape in which the maximum muscle strength ratio is a predetermined value (for example, 0.5 or less), a mother with a mixture of people with different hand lengths. It can be set as a container main body that any general consumer formed in a group feels easy to pour, and the container main body can be manufactured without performing a conventional sensory evaluation.

Claims (5)

A step of acquiring myoelectric potential information at the time of the maximum voluntary isometric contraction of the operating muscle related to the sense of burden when a series of pouring operations are performed by gripping and lifting the trunk of the container body and subsequently tilting the container body When,
Obtaining myoelectric potential information of the operating muscle when the pouring operation is performed;
Calculating the maximum muscle strength ratio represented by Equation 1,
A load estimation method for a container pouring operation, wherein the load in the pouring operation is quantitatively evaluated based on the value of the maximum muscle strength ratio.
(Equation 1) Maximum muscle strength ratio = Myoelectric potential during pouring / Maximum voluntary isometric contraction   The myoelectric potential information of the operating muscle is obtained separately from myoelectric potential information when the body of the container body is gripped and lifted and myoelectric potential information when the container body is tilted. Item 2. A method for estimating a burden of container pouring operation according to Item 1.   The movement muscle related to the sense of burden is selected from the first dorsal interosseous muscle, the long thumb abduction muscle, the total finger extensor muscle, and the lateral carpal extensor muscle as the movement muscle for evaluating the lifting movement. It includes at least any one type, and includes any one type of first dorsal interosseous muscle or total finger extensor and superficial digital flexor muscles as an operation muscle for evaluating the operation of tilting the container body. The burden estimation method of the container pouring operation according to claim 1 or 2.   The operation muscles related to the sense of burden include a first dorsal interosseous muscle, a long thumb abductor, a total finger extensor, a radial carpal extensor, and a superficial digit flexor. The method for estimating the burden of the container pouring operation according to 2. The body shape of the container body was determined so that the maximum muscle strength ratio in the pouring operation obtained by the method for estimating the load of the container pouring operation according to claim 1, 2, 3, or 4 satisfies 0.5 or less. A method for manufacturing a container body.