【正文】 運動傳遞的效果的定義。 除了要具備構(gòu)件回轉(zhuǎn)范圍的知識，制造這前先建立一個檢驗機構(gòu)“運轉(zhuǎn)”效果的度量方法也是很有用的。 我們已經(jīng)知道四連桿具有一個自由度。 畫運動圖和確定機構(gòu)自由度的過程，是機構(gòu)運動分析和綜合過程的第一個階段。我們所說的自由度，指的是使機構(gòu)所有構(gòu)件相對于機架具有確定位置所需要的獨立輸入的數(shù)目。 雖然四連桿和曲柄滑塊機構(gòu)的應(yīng)用非常廣泛，但是我們可以發(fā)現(xiàn)這些連桿機構(gòu)的性能仍然有限。連接動力源或原動件的桿叫輸入桿，有一個移動鉸和一個固定鉸。否則，該系統(tǒng)是一個非約束運動鏈。Matrixbased definitions have been developed which measure the ability of a linkage to transmit motion。 Note that the relative motion between links of a mechanism does not change indifferent inversions。 We already known that a fourbar linkage has one degree of freedom。 The process of drawing kinematic diagrams and determining degrees of freedom of mechanisms are the first steps in both the kinematic analysis and synthesis process。 By degree of freedom we mean the number of independent inputs required to determine the positions of all links of the mechanism with respect toground。 Linkages with more members are often used in more demanding circumstances。 a structure does not. Since linkages make simple mechanisms and can be designed to perform plex tasks, such as nonlinear motion and force ransmission, they will receive much attention in mechanism study. Mechanisms are used in a great variety of machines and devices. The simplest closedloop linkage is the fourbar linkage, which has three moving links (plus one fixed link) and four pin joints. The link that is connected to the power source or prime mover and has one moving pivot and one ground pivot is called the input link. The output link connects another moving povit to another ground povit. The coupler or floating link connected the two moving pivots, thereby “coupling” the input to the output link. The fourbar linkage has some special configurations created by making one or more links infinite in length。 The skeleton diagram serves a purpose similar to that of the electrical schematic or circuit diagram in that it displays only the essential skeleton of 黃石理工學(xué)院 畢業(yè)設(shè)計 (論文 ) 外文文獻翻譯 the mechanism， which， however， embodies the the key dimensions that affect its motion。（ spherical and helical joints as well as other connections that allow threedimensional relative motion are not included， as only planar motion in parallel planes are discussed here）。 Here， both choosing the type as well as the dimensions of the new mechanism can be part of kinematic synthesis。 The input crank of a crankrocher type can rotate continuously through 3600 ，while the output link just “ rocks”（ or oscillates）。 The resulting output force or torque is not only a function of the geometry of the linkage， it is generally the result of dynamic or inertia force which is often several times as large as the static force。用作機構(gòu)基本零件的一般機械裝置有三種類型： （ 1） 齒輪系統(tǒng)，在回轉(zhuǎn)軸之間通過接觸傳遞運動的齒狀零件。如果這樣的運動鏈至少有一個構(gòu)件被固定并且：（ i）如果至少有兩個構(gòu)件能保持運動，就變?yōu)闄C構(gòu)；（ ii）如果沒有一個構(gòu)件能夠運動，則成為結(jié)構(gòu)。 把四連桿的一個或幾個桿無限延長就會產(chǎn)生一些特殊的機構(gòu)。特別是當其它零件出現(xiàn)在同一圖中的時候。（球形運動副 .螺旋副 .以及允許三維相對運動的其它連接尚未包括進去，因為這里僅僅討論的是平行平面內(nèi)的平面運動。因此，選擇新機構(gòu)的類型和尺寸是運動綜合的一部分。作為一個特例，某些平行四連桿的長度等于輸出 桿的長度，連桿的長度和固定桿的長度也相等，輸入桿和輸出 桿都可以作整周轉(zhuǎn)動或者轉(zhuǎn)換成稱為反平行四邊形機構(gòu)的交叉結(jié)構(gòu)。為了分析低速運動或者為了更方便地掌握任一機構(gòu) 如何運動的方法，傳動角的概念是非常有用的。我們可以研究出一個關(guān)于四連桿各桿件絕對角位置的分析表達式。為了找出已知機構(gòu)某些瞬心的位置，肯尼迪（ Kennedy）的三心理論是非常有用的。