نوع مقاله : مقاله کامل پژوهشی

نویسندگان

1 فارغ‌التحصیل دکتری، هسته‌ی علمی سامانه‌های پشتیبان در توسعه‌ی سلامت، دانشگاه یزد، یزد، ایران

2 استادیار، هسته‌ی علمی سامانه‌های پشتیبان در توسعه‌ی سلامت / گروه مهندسی مکانیک، دانشکده‌ی فنی و مهندسی، دانشگاه یزد، یزد، ایران

10.22041/ijbme.2020.121521.1568

چکیده

مرز تعادل روشی برای سنجش تعادل پویا در کلینیک و آزمایشگاه است که تحت تاثیر موقعیت و سرعت خطی مرکز جرم بدن قرار دارد. در این مطالعه عامل تعادل از طریق روش مرز تعادل محاسبه شده و از آن به عنوان تابع هزینه جهت برنامه­ریزی مسیر حرکت برخاستن استفاده شده است. برای محاسبه­ی کینماتیک حرکت، از نمای ساجیتال حرکت برخاستن 10 مرد جوان و سالم فیلم‌برداری شده و یک مدل دوبعدی و چهار سگمنتی بر اساس معادلات حرکت، برای محاسبه­ی موقعیت مرکز جرم، گشتاور مفاصل و انجام فرایند بهینه­سازی تعریف شده است. پس از محاسبه­ی مسیر تعادل آزمودنی­ها با استفاده از روش مرز تعادل، انتگرال زمانی مسیر تعادل (C1)، مقدار حداکثر و حداقل تعادل (C2) و انتگرال زمانی مربع مسیر تعادل (C3) به عنوان توابع هزینه تعریف شده است تا توسط الگوریتم ژنتیک به حداقل برسد. برای بررسی کیفیت مسیر پیش­بینی شده توسط مدل و مقایسه­ی آن با الگوی­ آزمودنی­ها نیز از خطای جذر میانگین مربعات استفاده شده است. طبق نتایج این پژوهش، مدلی که با استفاده از تابع هزینه­ی C3 بهینه­سازی شده، الگوی حرکتی آزمودنی­ها را به ترتیب با 19% و 40% خطای کم‌تر نسبت به C1 و C2 پیش­بینی کرده است. با این وجود پیش­بینی دقیق حرکت برخاستن توسط هیچ­یک از مدل­های پیشنهادی ارائه نشده است. در نهایت می­توان نتیجه گرفت که استفاده از تابع هزینه­ی مرز تعادل به تنهایی، انتخاب مناسبی برای برنامه­ریزی حرکات تمام بدن نمی‌باشد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Optimization of Dynamic Stability Factor to Plan the Trajectory of Sit to Stand Movement

نویسندگان [English]

  • Mostafa Haj Lotfalian 1
  • Mohammad Hadi Honarvar 2

1 Ph.D., Center of Excellence for Support Systems in Health Development, Yazd University, Yazd, Iran

2 Assistant Professor, Center of Excellence for Support Systems in Health Development / Faculty of Mechanical Engineering, Yazd University, Yazd, Iran

چکیده [English]

Margin of stability is a method to assess the dynamic stability in the clinic and laboratory, which is influenced by position and linear velocity of the center of mass (CoM). In this study, the stability factor was calculated by the margin of stability (MoS) method and was used as a cost function to plan movement trajectory of sit to stand. 10 healthy young men were selected in this study and their sit to stand movement were filmed by Optitrack motion capture system. A two-dimensional and four-segment model was defined based on the governing equations of motion to calculate position of CoM, joints torque and using that in optimization process. After calculating the subject’s stability factor by MoS method, the time integral of MoS (C1), the maximum and minimum of MoS (C2) and the time integral of the square of MoS (C3) were defined as the cost functions. genetic algorithm was used to find the optimal model. To determine the quality of predicted trajectories and compare it with the subject’s pattern, root mean square error (RMSE) was used. According to the results of this study, a model which was optimized by C3, predicted the movement trajectory of subjects with 19 and 40 percent less error than C1 and C2 respectively.Nevertheless, none of the models could correctly reconstruct the subjects’ movement trajectory. In a nutshell, using MoS exclusively as a cost function, is not a good choice to predict and plane the trajectory of whole-body movements.

کلیدواژه‌ها [English]

  • Dynamic Stability
  • Margin of Stability
  • Movement Trajectory
  • Sit to Stand
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