IJE TRANSACTIONS A: Basics Vol. 26, No. 10 (October 2013) 1243-1254   

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B. Miripour Fard, A. Bagheri and A. S. Khoskbijari
( Received: February 08, 2013 – Accepted: April 18, 2013 )

Abstract    In some situations, when an external disturbance occurs, humans can rock stably backward and forward by lifting the toe or the heel to keep the upright balance without stepping. Many control schemes have been proposed for standing balance control under external disturbances without stepping. But, in most of them researchers have only considered a flat foot phase. In this paper a framework is presented that includes the foot tilting. This is done by hybrid modeling of the humanoid robot and also using a receding horizon based approach. The decision for the recovery pattern is done based on the evaluation of the Vertical Forces criterion. If the method predicts the tilting of the foot under disturbance, then the optimum trajectories are obtained for upper segments to return the robot to the secure posture in which the foot is flat (home posture). The obtained optimum trajectories are then tracked by a feedback controller. In the context of receding horizon approach the Extrapolated Center of Mass position has been used as the stability constraint. The results demonstrate the success of method to reproduce human-like balance recovery reactions under impulsive disturbances. The simulated results are compared with experimental data reported in the biomechanics literature.


Keywords    Hybrid Model, Receding Horizon Approach, Upright Balance, External Disturbances


چکیده    در برخی موقعيتها، اگر يک اغتشاش خارجی بر انسان در حالت ايستاده وارد شود، انسان می­تواند با رفتن بر روی پنجه و پا پاشنه پا و بدون نياز به گام­برداری، تعادل ديناميکی خود را حفظ کند و نيافتد. تاکنون طرح­های کنترلی بسيار زيادی برای کنترل ايستادن در برابر اغتشاش خارجی، بدون گام­برداری پيشنهاد شده است. در بيشتر طرح­های پيشنهاد شده، پژوهشگران جهت ساده­سازی مساله، فرض کرده­اند که در هنگام بازيابی تعادل، کف پا همواره افقی می­ماند. در اين مقاله چارچوبی ارايه می­شود که شامل دوران پا هم می­شود. اين کار از طريق مدل­سازی هايبريد و استفاده از طرح کنترلی بر اساس روش کنترل با افق پسرو انجام شده است. تصميم­گيری برای انتخاب الگوی بازيابی تعادل بر اساس ارزيابی معيار نيروی عمودی تکيه­گاهها در يک افق پيش­بينی انجام می­شود. اگر پيش­بينی­ها حاکی از دوران پا در اثر اغتشاش باشد، الگوی حرکتی مناسبی برای اعضای بالايي ربات (اعضاء دارای عملگر) به دست می­آيد تا کف پا (عضو بدون عملگر) را به حالت افقی برگرداند. الگوهای حرکتی به دست آمده توسط يک کنترل کننده پسخورد اجرا می­شوند. در روش کنترل با افق پسرو، معيار بردار برونيابی شده مرکز جرم به عنوان قيد پايداری استفاده شده است. نتايج، نشان دهنده موفقيت روش در توليد حرکاتی مشابه انسان در برابر اغتشاش ضربه­ای خارجی است. نتايج شبيه­سازی با نتايج تجربی موجود در منابع بيومکانيک مقايسه شده است.


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