Abstract
本研究では、構造解析手法の一種であるShifted Integration法に用いられる有限要素によるリンク機構のモデル化を試み、関節トルクの並列的な算出方法を導出した。ニュートン・オイラー法などがリンク情報を 直列的に扱うのに対し、本計算法では節点力を並列的に算出することが可能となるため、リンクやジョイントの増減および故障などに柔軟に対応で きる。本論文では、本手法を従来の手法では動力学方程式を算出することが困難な超冗長マニピュレータに対して適用した。算出されたトルクの精度および計算時間の比較をした結果、このような系の逆動力学計算において本手法が有効であることが確認された。
In this study, link mechanisms are modeled using finite elements based upon the Shifted Integration technique, and a new calculation scheme for obtaining the inverse dynamics is proposed. A single link structure of a pin joint and a rigid bar is expressed by two linear Timoshenko beam elements with their numerical integration points shifted to opposite ends of the link joint. The finite element approach in control schemes may provide flexibility against sudden change in a hardware system, since the remodeling can be achieved easily by rewriting input data. This paper describes an application of the proposed scheme to normal pin joint-rigid bar link mechanisms. The process of calculating the inverse dynamics in n-link mechanisms based upon Cartesian coordinates is shown, and a numerical test on an 8-link mechanism by the Finite Element Method is carried out. The obtained joint torque curves as well as the calculation time are compared to those obtained by the conventional Newton-Euler method. By also carrying out a calculation on a 100-link mechanism, which is extremely difficult for any other conventional schemes, the flexibility and the practicability of the proposed scheme are verified.