ひずみエネルギの抑制を目的としたロボット機構の姿勢決定および動作計画
Attitude Determination and Motion Planning of Robotic Architecture for Restraining Strain Energy

Abstract


 特に低強度なロボット機構に対しては,部材降伏が生じるような強度的に危険な姿勢を回避した姿勢決定や動作計画を行う必要がある.本研究では,外力によって蓄積される全ひずみエネルギを機構の安全性を示す指標とし,これが抑制された姿勢を決定するアルゴリズムを開発した.なお,機構の内力解析には有限要素法を用いた.全ひずみエネルギを抑制した姿勢は,直接探索法を用いた収束計算によって導出される.さらに,本姿勢決定アルゴリズムをロボットの動作計画に適用し,危険な姿勢を回避した軌道を導出するアルゴリズムを開発した.本動作計画では,動作中に降伏危険性が判定されると,前述の姿勢決定が行われ,得られた姿勢を経由して最終的な目標姿勢に向かう軌道が作成される.本研究では,これらのアルゴリズムを用いて,簡単な例題に対する姿勢決定および動作計画を行い,実際の問題を取り扱う上で必要となる基礎的な知見を得た.


This paper describes a new way of attitude determination and motion planning of robotic architecture by aiming restraint of total strain energy stored in the architecture. By using this scheme, a robotic architecture can avoid yielding of its constituting link members. In the motion planning, when the risk of member yielding becomes higher while the robot is in motion, a safer attitude for restraining its total strain energy is searched. At the next step, a new trajectory is created, beginning with the obtained attitude, and ends with the final target which is initially given. The procedure is repeated until a converged attitude is obtained. Risk for member yielding and total strain energy are calculated by Finite Element Method (FEM), and an attitude for restraining total strain energy is searched by Direct Search Method. Some numerical tests are carried out with a truss-type robotic architecture and a 3-link manipulator, and the results show a possibility of using strain energy as a new parameter for attitude determination and motion planning.


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