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Recently, Japan's Kao Corporation's Health Products Research Institute and Personal Care Research Institute announced that Kao has developed a new "mGCC technology" (mobile Gait Change Capture, mobile gait change capture technology). Through the application of this technology, the two-dimensional video shot by smart phones and other devices can be converted into three-dimensional walking action data, and analyzed in detail.

At present, "motion capture technology", which is commonly used in motion analysis research, has the advantages of high accuracy and can correctly analyze three-dimensional walking movements. But on the other hand, the application of "motion capture technology" is easily restricted by venue and time due to the need to set up and install multiple infrared cameras and other equipment in advance. In addition, it is also necessary to affix multiple reflective markers for measurement on the test object, which requires high measurement skills and time for the entire measurement process.

In this context, Kao began to develop a more convenient and effective method for analyzing walking movements, thus successfully developing a brand-new "mGCC technology" that can analyze three-dimensional walking movements in detail by shooting two-dimensional videos with smart phones ". This technology can perform machine learning on two-dimensional videos taken by ordinary digital cameras (RGB cameras) commonly used in general smart phones, and calculate and analyze the three-dimensional movements of human skeletal points.

Kao used "motion capture technology" to measure the walking of 99 children aged 13 to 37 months, and took pictures of the children's walking process with ordinary digital cameras. After that, from the three-dimensional data obtained by "motion capture technology" to extract a number of walking parameters with a high correlation with the age of the child for multi-regression analysis, thus calculating the age of the child.

At the same time, Kao uses "mGCC technology" to analyze the three-dimensional data converted from the two-dimensional video taken by the ordinary digital camera, and uses the same multiple walking parameters as above to analyze and calculate the age of the child. Finally, Hua Wang compared the age of children calculated by the above two methods, and verified the effectiveness of quantitatively calculating the development of children's walking ability by shooting two-dimensional walking videos. The verification results show that the age of children calculated by "mGCC technology" has a high correlation with the age of children calculated by "motion capture technology" with high measurement accuracy. This proves that "mGCC technology" and "motion capture technology" have almost the same accuracy in estimating age. The use of "mGCC technology" can be directly through the shooting of two-dimensional walking video can quantitatively calculate the degree of development of children's walking, effective and more convenient.

research significance

The data obtained from this study, which are constantly changing with the development of children's walking ability, reveal the timing of changes in the movements of various joints during the development of infants from the stage of large forward pelvic inclination, split feet (hip joint opening) and faltering at the beginning of walking to the stage of steady walking with small forward pelvic inclination and folded feet (hip joint internal closure) (fig. 1). As an important research result of the research on the development of children's walking ability, the digitization of walking movements has high practical value in the future, and for children before the age of 3 who have great changes in walking state, these data also confirm that the diapers worn every day will have an impact on their walking.

In 2011, a survey on the objective indicator of children's daily exercise, that is, the number of walking steps, showed that children's walking amount exceeded parents' imagination. And after the Japanese government announced the implementation of the emergency declaration in 2020 to prevent the spread of the new crown epidemic, a step-by-step survey for young children also confirmed that the amount of activity of young children was more affected than that of adults.

This survey focuses on the quality of walking. The use of motion capture technology is not limited to general walking measurement indicators such as stride length, but combined with motion analysis including pelvic and joint angles, the lower body movements are modeled as shown in Figure 1, so as to clarify the internal mechanism of children's walking ability development, and further explore the impact of wearing diapers on children's walking.

This test was completed under the guidance and cooperation of Dr. Hiroshi Iwasaki from Japan's Ten Children's Clinic, Professor Hisashi Uito from the Institute of Sports and Health Sciences of Shunyuan University, and Professor Lu Dajiang from Shanghai Institute of Physical Education.

research results

The measurement of walking using motion capture technology is shown in Figure 2. Specifically, an infrared reflective marker is placed on the infant's body, position information is acquired by an infrared camera, and the walking state is converted into digital data.

(1) Reveal the internal mechanism of the development of children's walking ability.
Condition: Wearing daily commonly used diapers (clean state without urination) walking independently.
Measurement indicators: ① pelvic tilt condition; ② hip joint opening degree; ③ knee curvature; ④ ankle movable angle range; ⑤ stride length; ⑥ foot spacing (lateral interval between left and right feet);⑦ body center of gravity swing condition.

Results:According to the number of months that can walk (the number of months that can walk independently), the observation objects were divided into 4 groups for analysis at a stage of every 6 months. In the development process from unstable walking at first to steady walking, it is confirmed by analyzing when and what changes occur in the above indexes of ① ~ ⑦ that the indexes do not change at the same time, while the angle changes of lower limb joints occur from pelvis and hip joint, through knee joint, and finally to ankle, that is, from near the center of the body to the distal end (fig. 3). Through indicators ①-⑦ to master the walking characteristics of the first to sixth months, as a reference to show what changes have taken place in the subsequent stages. It can be seen that the change of each index occurs in different periods, and the walking ability develops gradually according to this.

(2) Confirm the impact of diapers on walking.

Observed: Japanese and Chinese children who can walk independently. Japan: 13 children aged 12-25 months; China: 26 children aged 18-20 months.

Conditions:Two types of diapers having different structures (Sample A, Sample B) were worn and three cases were not worn, respectively. Because it is preset to urinate, the diaper has absorbed 160 grams of normal saline.

Measurement indicators: foot spacing (horizontal spacing between left and right feet), body center of gravity swing.

Results:Through the experiment of children aged 12-25 months in Japan, the difference of foot spacing and body center of gravity swing when wearing diapers and not wearing diapers was observed, which confirmed that diapers have an effect on children's walking. However, in the proof experiment conducted in China for children aged between 18 and 20 months, it is found that there are differences in walking conditions when wearing different diapers (sample A and sample B). It can be seen that sample A has a structure that does not fall and deform after absorbing water in the crotch, so it has less influence on walking.

According to the above-mentioned "revealing the internal mechanism of the development of children's walking ability", different walking months have different walking characteristics. The age of the experimental subjects is specified to reduce the deviation caused by different walking ability, which highlights the influence of diapers on walking. This also suggests that the need for further verification should be carried out separately according to the age of the month.

Outlook

Through the use of the newly developed "mGCC technology", it is possible to conveniently and effectively monitor the effect of the degree of walking development of children without installing professional measuring devices and only using smart phones and other equipment to shoot videos of children's daily walking. In the future, Kao plans to further apply this technology to the research field of children's development and development, hoping to provide strong support for the product development of infant diapers and the development of childcare related services.

Source: Kao

Source: Jung-International Nonwovens Industry