نوع مقاله: مقاله کامل پژوهشی

نویسندگان

1 دانشجوی دکترا، گروه بیوالکتریک، دانشکده مهندسی پزشکی، دانشگاه صنعتی امیرکبیر

2 دانشیار، گروه بیوالکتریک، دانشکده مهندسی پزشکی، دانشگاه صنعتی امیرکبیر

10.22041/ijbme.2011.13146

چکیده

با توجه به مطالعه‌های صورت گرفته، سیستم حرکتی انسان از دو استراتژی کنترلی، کنترل مدل‌مبنا و کنترل امپدانسی، به منظور یادگیری حرکتی و مقابله با اغتشاش‌های خارجی استفاده می‌کند اما نحوه تعامل این کنترل‌کننده‌ها و چگونگی هماهنگی بین آنها چندان بررسی نشده است. در این مقاله با بهره‌گیری از یک کنترل کننده سرپرستی، نحوه یادگیری حرکت و عملکرد کنترل کننده‌های امپدانسی و مدل‌مبنا بررسی شده است. کنترل‌کننده سرپرستی با پایش رفتار و خروجی سیستم، وظیفه هماهنگی مابین کنترل‌کننده‌های امپدانسی و مدل‌مبنا را بر عهده دارد. بر این اساس دستور حرکتی جلوسو و سفتی مفاصل به‌صورت جداگانه و همزمان تنظیم و اصلاح می‌شوند.  به‌منظور ارزیابی مدل ارائه شده، حرکت‌ رسنده دست در حضور میدان نیروی اغتشاشی، شبیه‌سازی و با نتایج تجربی مقایسه شده است. نتایج به‌دست آمده نشان‌دهنده آن است که برای انجام حرکتی طبیعی، علاوه بر امپدانس مناسب حرکت، بایستی مدلی درونی از حرکت نیز در اختیار سیستم کنترلی باشد. علاوه بر این از آنجا که اندازه امپدانس متناسب با میزان یادگیری بهینه می‌شود، بیشترین یادگیری در جهتی است که خطای حرکتی بیشتر بوده و مفاصل امپدانس کمتری دارند. همچنین نشان داده شده است که سیستم حرکتی در مواجهه با اغتشاش‌های ناگهانی، با استفاده از تغییر امپدانس و کاهش اثر کنترل کننده مدل‌مبنا سعی در جبران خطای حرکتی می‌کند که این امر به معنای استفاده از تجربه‌های پیشین توسط سیستم سرپرستی است.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Modeling of Impedance and Model Based Controllers Function in Learning Arm Reaching Movement

نویسندگان [English]

  • Ali Falaki 1
  • Farzad Towhidkhah 2

1 PhD Candidate, Bioelectric Group, Bioengineering School, Amirkabir University of Technology

2 Associated Professor, Bioelectric Group, Bioengineering School, Amirkabir University of Technology

چکیده [English]

Based on previous studies, human motor control system may apply two control strategies, impedance control and model based control, for learning motor skills and counteracting environmental instabilities. Since interaction among these controllers is not fully studied, the investigation of impedance and model based controllers function during learning period seems desirable. In this study a supervisory controller was used to coordinate the model based and impedance controllers. Coordinating model based controller and impedance controller by using supervisory unit will result in simultaneously adjustment of forward motor command and joint stiffness. In order to evaluate performance of the suggested model, it was applied to arm reaching movements in the presence of external force fields. Results showed that both suitable impedance values and a proper internal model are required to fulfill movements similar to those of humans under different circumstances. Research has shown that central nervous system is able to purposefully modulate arm impedance to counteract environmental disturbances. This study showed that beside this modulation, the maximum motor learning may occur in direction with the least impedance and the most kinematic error. It also concluded that confronting abrupt changes in disturbance, the system managed to decrease error without learning the new dynamic using previous knowledge by supervisory system. A part of this compensation is due to stiffness variations and another part is due to decreasing the influence of model based controller.

کلیدواژه‌ها [English]

  • Arm Reaching Movements
  • Impedance control
  • supervisory control
  • Model based control
  • Modeling
  • Movement learning

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