Design of a Spherical Reconfigurable Linkage for the Control of Mechanism Center of Rotation

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Title:	Design of a Spherical Reconfigurable Linkage for the Control of Mechanism Center of Rotation
Authors:	王玟心;Wang, Wen-Hsin
Contributors:	機械工程學系
Keywords:	遠程運動中心;球面並聯機構;運動學分析;可重構機構;機械設計;Remote Center of Motion;Spherical Parallel Mechanism;Kinematic Analysis;Reconfigurable Mechanism;Mechanical Design
Date:	2022-08-29
Issue Date:	2022-10-04 12:14:58 (UTC+8)
Publisher:	國立中央大學
Abstract:	許多研究顯示，具有遠程運動中心（remote center of motion，RCM）之機構在微創手術或遠端超音波技術等醫學應用中非常有效。進行上述醫學應用時，醫療裝置或醫療器材通常繞著一點旋轉，該點稱為轉動中心（center of rotation，CoR）。前述兩例中，控制旋轉物件的轉動中心位置均有其必要性，無論是在進行醫學應用的過程中或作為預調皆是如此。然而，大部分具有遠程運動中心之機構無法將其末端效應器的轉動中心復位。把這些機構裝在作直線運動的平台上是解決問題的方法之一，但這個構想會大幅增加整體體積與重量。本研究透過可重構機構提出更小巧、輕盈且或許更便宜之替代方案，即名為球面可重構連桿（spherical reconfigurable linkage，SRL）的新概念。傳統球面機構透過球面連桿的旋轉節點軸之交叉點來限制轉動中心。本研究提出的球面可重構連桿刻意在改變其半徑時仍維持其節點軸，使機構能夠自行將轉動中心復位，因而不需要額外的線性運動平台。對球面可重構連桿作概念性定義後，本研究進行運動學分析以研究重構與轉動中心運動之間的關係。本研究設計並製作一具球面可重構連桿的原型，以測驗上述理論的可行性。本研究使用球面可重構連桿，設計擁有二角度自由度（degree of freedom，DoF）之球面並聯機構（spherical parallel mechanism，SPM），並將其以傳統方式裝設為球面五連桿。本研究改良此球面並聯機構，使其能用兩個額外的線性自由度使其能移動其旋轉中心。在定義結合球面可重構連桿所需之架構改良後，本研究對其運動學和速度模型進行研究。 ;Several studies have shown that mechanisms with Remote Center of Motion (RCM) are very useful for some medical applications, such as Minimally Invasive Surgery or tele-echography. In these applications, medical devices or instruments are being rotated around a point that is called the Center of Rotation (CoR). In both cases however, it is necessary to control the position of the CoR of the manipulated object, either during the process, or as a preliminary adjustment. But most RCM mechanism are unable to reposition the CoR of their end effector. A simple solution to this issue is to mount them on a platform that provides linear motions. However, this conceptual design suffers from a significant increase in volume and weight. By the mean of reconfigurable mechanisms, the present study suggests a more compact, lighter and possibly cheaper alternative. In this regard, a new concept of Spherical Reconfigurable Linkage (SRL). Classical spherical architecture mechanisms rely on spherical linkages which are known for constraining the CoR by the intersection of their revolute joint axes. In the present concept, the SRL has been specifically imagined to change its radius while maintaining its joint axes, in order to reposition the mechanism CoR by themselves, thus suppressing the need for an additional linear platform. Following the conceptual definition of the SRL, its kinematic analysis is provided to find the relationship between its reconfiguration and the resulting CoR motion. A prototype is then designed and fabricated to test the feasibility of such concept. Using the SRL, a Spherical Parallel Mechanism (SPM) with two angular Degree of Freedom (DoF), which is classically mounted as 5-bar Spherical Linkage is improved into a new mechanism capable of displacing its CoR with two additional linear DoF. After defining the architectural modification required for the integration of the SRL, its kinematic and velocity models are studied.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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