機構式四輪轉向核心機構之設計與模型製作

Design and Prototype for a Centralized Four-wheel-steering Mechanism

四輪轉向大致可分為四輪獨立式與機構傳動式兩大類型，四輪獨立式的學術研究不少，但考慮穩定性與安全性，目前實用化的轉向機構仍然以機構傳動式為主，且已有車廠提出不同的四輪轉向概念。然而，這些研究與設計皆針對高速行駛的小轎車與固定的前後轉向角度函數，並未針對低速停車特性與可變轉向角度函數提出構想。本文構想出可變轉向角度函數的機構傳動式轉向機構，並融入四輪獨立式的優點，在保持轉向機構安全性的前提下，增加四輪轉向的操控性與自由度。四輪轉向系統的主要目的是為減少車輪之側滑角，其中以連接前後輪轉向機構之間的核心機構(Central Device)之設計為主要工作。本文之目的在於設計一組平面連桿組之核心機構，以應用於車輛的機構式四輪轉向系統。首先分析核心機構的構造與特性，提出設計方法與流程，設計出四輪轉向核心機構概念，再配合特定的設計需求，評估設計結果並進行四輪轉向模型的設計，並利用分析軟體進行運動模擬，最後建立電腦模型與製作實體模型，以測試並驗證設計結果。

The The The Four-wheel steering (4WS) can be classified both by its having four independent wheels and the type of mechanism used in the transmission. The type with four independent wheels has been studied widely. However, when the factors of stability and safety are considered, the type of mechanism used in the transmission has come to generally be considered first and applied to the practical design. Therefore, the type of steering mechanism which is based on a transmission mechanism with the ability to change the angle is studied in this paper. Based on the safety of the mechanism’s operation, the characteristics of operation and degree of freedom will be increased. The main design topic in many kinds of 4WS systems is how to reduce the slip angle. The central mechanism is the key device for connecting the front and rear wheel steering in a 4WS system. The purpose of this paper is to explain a new design of the central mechanism using a mechanism type 4WS system which uses planer linkages. The central mechanisms and their characteristics are analyzed and. a design method and flowchart for the central mechanismis presented. Some new concepts have been discovered in the development of this method. The synthesized results are evaluated in light of some specific requirements and the generated results analyzed by appropriate software. The computer model and its prototype have been successfully built.