電動輪椅跨階機構設計最佳化之研究

Abstract

本文以六輪電動輪椅跨階機構設計的最佳化為目標，藉由整合機構動力分析與結構有限元素分析之最佳化設計方法來進行研究。電動輪椅有動力系統的輔助，加上操控容易，比傳統的手動輪椅有更大的活動空間，因速度較快，結構與機構組件承受的動力效應更為嚴重與明顯，結構設計不能只有考慮最大靜力的問題，因此結構強度設計要考慮加上動力作用於機構組件所衍生的問題。本文在機構運動分析方面是以MSC/ADAMS模擬分析電動輪椅在跨階過程進行中，機構組件產生的慣性力、慣性力矩與桿件各接頭處的受力狀態，接著藉由有限元素分析軟體ANSYS來分析加速度對結構所產生的應力分布情形，藉此針對結構需要加強的部分加以改良或加強。本研究旨在藉由整合機構運動與結構應力分析的方式找出輪椅在動態運動中的最大結構應力。接著以最小重量為設計目標，利用尺寸最佳化設計計算出最佳的幾何尺寸以及設計出一個最佳化的機構模型。

This research focuses on the mechanical design optimization of power wheelchair for step climbing. The transient dynamic effect was concerned by integrating multi-physics theories: the kinematics, dynamics, material strength etc. to solve for the optimal design on the mechanism component especially on the case of impact situation. It is not easy to control and measure the small scale experiment model of proposed PWC wheelchair. Since that the dynamic effect of the PWC system is serious and obvious. Thus, the structural design can not consider maximum static force only, therefore, the design issue of structure need involving dynamic effect that acting on mechanism components. The analysis and simulation stage in our design process are cooperated by two main topics. They are motion analysis involving pre-modeled component mesh and structure dynamics analyzed by adopting the FEA method. For motion analysis of power wheelchair climbing the step obstacle, MSC/ADAMS was introduced to simulate the inertia force and moment exiting at components located at connectors etc. Finite element analysis software ANSYS was adopted to analyze the distribution of the stress that acting on the structure. This analysis was to improve or strengthen the structure in accordance with the material strength. State on the other hand, this research aims to find out the maximum structure stress of wheelchair among dynamic motion by integrating the analysis methods of mechanism motion and structure stress analysis method. Minimum weight as the design object, utilize size optimization to calculate out the best size of geometry and design an optimum mechanism model. The current research proposed a methodology by integrating the kinematics, dynamic analysis and FEA method, have been implemented to demonstrate its efficiency and correctness.