模擬系統之兩軸力回饋搖桿設計與控制

Abstract

使用者與虛擬實境動態模擬系統之間的即時互動，必須透過雙向互動層次的力覺裝置，方能達到緊密結合的效果，力回饋搖桿即為此裝置其中一種，我們不僅利用力回饋搖桿來操控虛擬場景中的物件，而且真實感受到其與虛擬物件之間的相互影響。本論文首先介紹一般力回饋搖桿的設計概念、硬體結構、操作感受、特性分析、及信號處理，並依此開發一具有高頻寬、高精確度、及高輸出力矩的力回饋搖桿，且分析此搖桿的性能及可發揮的空間，接著推導其數學模型，以方便分析及模擬，最後設計適合此搖桿的驅動程式。在實驗方面，我們利用此搖桿進行模擬使用者與簡單物件之間互動行為的基本性質實驗，例如彈簧、阻尼、質量等，接著將三種基本性質合成一阻抗元件，以詮釋力回饋搖桿與簡單物件的互動行為，而與複雜物件的互動行為則可分解成一些簡單行為的相互影響，另則討論與一些極端虛擬物件的互動行為，如虛擬牆等，最後利用其原理實作出運動限制(motion constraint)的應用，如排檔器等。由實驗結果得知，此力回饋搖桿確實可賦予使用者更擬真的力覺感受，而且能更有效率地與系統溝通。

The interaction between the user and a virtual reality dynamic simulation system can be much enhanced by the haptic devices, which provide two-way communication in position and force. The force-reflection joystick is a typical haptic device. We use it to manipulate the objects in the virtual environment, and also emerge into the activities among the virtual objects. In this thesis, we first discuss the important issues in developing a force-reflection joystick, including the design concept, hardware structure, manipulativity, system analysis, and signal. Based on the discussions, we design a 2-DOF force-reflection joystick, which is with high precision, bandwidth, and output torque. Since the joystick is intended for simulation system in the experiments, we first use it to generate the feeling of touching the spring, damper, and mass. More complex feeling can then be generated by synthesizing these three basic properties. We also use the joystick and software to construct the “virtual wall”. As a novel concept, we propose a method to assemble the virtual walls. With a set of virtual walls properly arranged, they can form certain virtual motion constraints, and thus emulate various virtual mechanisms, such as the gearshift box.