外文文獻翻譯-基于原型液壓系統(tǒng)特征的機構模型【中文3550字】 【中英文WORD】,中文3550字,中英文WORD,外文文獻翻譯-基于原型液壓系統(tǒng)特征的機構模型【中文3550字】,【中英文WORD】,外文,文獻,翻譯,基于,原型,液壓,系統(tǒng),特征,機構,模型,中文,3550,中英文,WORD - 4 - 中文譯文 基于原型液壓系統(tǒng)特征的機構模型 摘要：本文為原型液壓系統(tǒng)的設計提出了一種基于特征的方法。它提出了一個框架,允許設計師以更加直覺的方式開發(fā)一個真實液壓機構原型，例如， 通過真實的工程學數據進行設計。這種方法是在真正原型數據的基礎上發(fā)展起來的， 它可以分離信息入行為，結構，和產品屬性。這些屬性被用適當的表示法提出， 并且框架為基于特點的真正原型 的方法建立，根據組分等級結構在一種液壓機構。它所提出的框架不只是真實的液壓系統(tǒng)的一個精確模型，而且為設計成員提供了當由于某些零件的一些特性改變導致系統(tǒng)改變而獲得一個新的液壓系統(tǒng)精確模型的可能性。 關鍵詞: 計算機輔助工程; 液壓動力系統(tǒng);真實樣機 1. 介紹 液壓機構設計可能被看作是一個為映射明確套要求入物理可實現的液壓能力系統(tǒng)的作用對形式變革過程。這個過程涉及三個主要階段: 功能規(guī)劃階段，結構設計階段， 和樣機制造階段。描述各個設計階段的所用的格式是不同的。 功能的規(guī)劃是所有設計中最初的工作。為了達到這個要求， 設計問題是以指定的書信和印成單行本發(fā)給新加坡南陽大道南陽技術大學機械和制造工程的Dr S. C. Fok。明確地根據作用和表現。設計師必須確定產品的性能和屬性， 其中包括壓力， 強度， 速度和流體速度， 以及一些所必需的東西如尺寸大小，成本, 安全要求和操作順序。其次， 設計師必須敘述出各個特征的精確性能要求。在這個階段，設計以摘要的形式寫出產品的相關性能要求。 結構設計階段的目標是完成一個液壓系統(tǒng)回路。這個回路能完成系統(tǒng)設計參數規(guī)定的各個功能。一種典型的液壓機構由許多子系統(tǒng)組成。組成子系統(tǒng)的最小模塊是標準液壓系統(tǒng)元件(譬如閥門， 氣缸，液壓泵等。). 每種液壓標準元件都有各自的特殊作用。結構設計階段的任務就是從根本上找到一個基本液壓元件（例如液壓回路）的布置圖。這個基本的液壓回路能達到系統(tǒng)的各個功能要求。根據這個結構， 設計師通常把整個系統(tǒng)功能模塊分成一個個最基本的子函數。這樣就能隔開搜索空間，通過搜索較小一級的液壓系統(tǒng)基本回路去實現各個子函數的功能要求。 在外觀設計過程中計算機往往會發(fā)揮很大的作用。例如， Kota 和Lee 想出了一個基于圖表的液壓系統(tǒng)回路結構的自動設計方法。在液壓回路被發(fā)展以后，人們經常被使用數字模擬實驗工具來學習和評估這些結構。通過這些工具， 設計師能比較不同的電路塊的功能，并且能夠分析出這些功能塊結合后的效果。在結構設計階段，傳統(tǒng)上設計往往用一張回路圖來代表標準元件。這里是被(C ，E)包含結構C 的回路S以結的形式聯系組分之間由邊E 表示的地方圖表的形式。 樣機設計階段是結構設計過程中提出的液壓回路的證明階段。通過這個階段能證明結構設計中對回路的提出與評估是否正確。實際樣機的目的是建立液壓機構666 S 的一個物理原型。使用工業(yè)可利用的零件。 涉及真實樣機的過程以下: 從不同的制造商手中尋找適當的標準零件。零件的選擇和評估是建立在零件之間的成本，尺寸大小，規(guī)格和互換性等因素之上的。選擇的零件取得和裝配。根據整個系統(tǒng)要求測試和評估物理原型。使用其它零件或重新設計電路(或支電路) 如果需要。除動力學以外， 物理原型的發(fā)展必須考慮到其它因素包括結構，成本與重量。動力學數據用來確認液壓動力系統(tǒng)的性能，但是幾何學信息用來系統(tǒng)的安裝性能。 物理樣機的研制將提供設計產品的真實性能，結構和設計成本。 物理樣機的主要缺點是, 它必須非常繁瑣和費時地從在許多制造商手中尋找一套標準零件的適當組合。由于設計的變化，從不同的制造商購買的同樣類型的標準零件的作用都不相同， 他們的動力學， 結構和費用特征也不可能相似。因此， 為同樣的一個液壓回路，選擇不同的制造商的標準零件去組裝，所完成的系統(tǒng)，最后在力學、結構和產品的成本等方面也會不同。在這一過程中可以使用評估工程，通過在零件標準特性上的改變來改進在這個情況下的系統(tǒng)設計。其中就包括最優(yōu)化的性價比率和對零件大小進行最合理的設計。真正樣機設計過程可能被觀看作為一個計算機輔助設計過程， 它可以使用模擬制造和模擬仿真工具來驗證樣機的物理布局，操作，功能規(guī)格，以及在在各種各樣的操作環(huán)境下的力學分析。虛擬樣機的主要好處是, 不需要實際零件，通過使用數字計算機就可以對一個液壓機構原型進行裝配和分解，因而大大的節(jié)省了時間和費用。 一個真正虛擬液壓機構樣機的主要要求是，它必須能像真實的產品一樣，為設計者提供信息和幫助他們做出決定。為了達到這個要求， 虛擬樣機必須提供另外不同數據的適當和全面表示法。 此外，從一個表示方法到另一個表示方法的改進應該進行下去。 Xiang 等?；仡櫫诉^去和當前的液壓動力系統(tǒng)的計算機輔助設計和樣機制造工具。工作顯示, 當前的工具不能在樣機制造階段為設計評斷提供一個完全抽象的設計表示法。 大多工具集中在動力學行為。 而與系統(tǒng)原型需要考慮和評估關系密切的重要幾何信息和產品信息往往被錯過。在液壓動力系統(tǒng)的虛擬樣機制造方面，為推進虛擬樣機計算機輔助設計工具的發(fā)展，有必要找到一種把性能、結構和產品數據這些獨立的抽象信息綜合在一起的正式表示法。這篇論文以這些問題中心，提出一個統(tǒng)一元件模型的標準和以基于特征方法為基礎的分類學。 在第二部分， 我們討論了基于特征的方法，這些方法主要集中在液壓系統(tǒng)模型化所要求的關鍵信息和他們的表示方法上。 第三部分主要介紹的是基于特點的模型標準和為虛擬液壓系統(tǒng)模型發(fā)展而提出的結構。并通過一個例子來說明這種結構。論文的第四部分是結論和展望。 2.基于特的方法 那些特征可以定義為信息塊，這些信息塊是涉及到設計、工程或者制造過程方面的特性。其中使用的特性集成CAD、CAPP與CAM的概念并不是新出現的，在CIM中就有許多有關這種應用的論文。在所有這些應用中，特征模型被認為是基礎，而通過特征進行設計是所有東西綜合的鑰匙。 為了開發(fā)一個特征模型，必須能夠識別與設計有關的信息，并能根據信息的性質進行分組。有關的信息應該包含諸如設計，分析，測試，文件，檢查和收集活動的足夠的知識，還有支持各種各樣管理和后勤的功能?；谔卣鞯脑O計是使用特征作為原始實體模型過程的設計。特征模型提供了標準化的有關數據。 通過特性接近的設計，設計中的至關重要的知識將被產生和存儲。為了避免這些問題，特性的類型，表示和結構問題應該在使用基于特征的設計方法之前被解決。當開發(fā)一個特征模型時，主要關注的是它的具體應用。在液壓系統(tǒng)的虛擬模型制造領域中，標準元件組成部分的細節(jié)必須能夠用來描述整個系統(tǒng)。同樣的，用于液壓的系統(tǒng)特性表示的一種分層結構將通過把系統(tǒng)考慮為子系統(tǒng)的分層而得以進化。為虛擬模型的一個適當的描述所要求的必要信息必然不少于設計者為了決策而引出物理的原型中的信息。這些數據應該一般包括形狀，重量，性能特性，成本，尺寸，功能參數等。與物理的原型化過程所要求的信息相比，對每種標準元件所需要信息能被分成完全不同的三類： 行為屬性，結構屬性，和制造屬性。依據用于滿足功能要求的動力學特征可以定義一個液壓元件的行為?？紤]到液壓的圓筒連接裝載，其功能是把力從活塞傳送到負載。 它能傳送的最大力能被用來定義功能和行為。在期望的根據期望的負載加速度特性可以劃分各種要求。因此，對于一個液壓元件，并且為動力學特征所反映的行為屬性可以表達功能。 依據期望的動力學特性，設計者對整個系統(tǒng)的行為特征的適當定義負責。一個標準元件有其自身的行為并且提供具體功能。不能被一個單一的標準元件完成的復雜功能使用使用多個元件。 因此，標準元件的行為將起重要的作用，因為與各個元件的獨自功能以及它們的布置同時改變整個系統(tǒng)的功能。 一個標準元件的性能可能是非線性的并且可以依賴于操作的條件。 當兩個組成部分被組合時，它們的行為相互作用并且產生不希望得到或者非故意的特性是可能的。這些不需要的行為被假定在配置期間被解決設計階段。 用于原型階段的液壓的電路被假定實現同時，沒有任何不受歡迎的人相互作用的行為。 這意味著一個組成部分的輸出行為將提供輸入到后來的組成部分。表示行為因為液壓的系統(tǒng)廣泛地已被調查。 這些表示包括轉移功能，狀態(tài)空間和合同圖表。 轉移功能(對于單一輸入的單一輸出系統(tǒng))和狀態(tài)空間方程(對于多重輸入的多重輸出系統(tǒng))基于關于一個名義的操作條件的動力學的逼近。力量合同圖表模型基于在液壓的系統(tǒng)中描述能量轉換的有原因的結果。 這接近對液壓的系統(tǒng)分析有感染力。 主要的不利是一種復雜的流體力量系統(tǒng)的一張合同圖表中的動力學方程的起源能變得十分乏味。 因此，最近工作已集中于代表在輸入和輸出數據之間繪制地圖的非線性使用人工智能，這能通過實驗的工作被獲得。 這些非線性能使用人工的網絡被完成。 液壓的系統(tǒng)設計者一般會使用輸入輸出來數據描述一個液壓的組成元件的特性 一個液壓的系統(tǒng)的結構設計經常通過功能分解的步驟取得。 為了設計一個液壓系統(tǒng)，設計者常常把它的功能和要求分成一個個最簡單的基本單元。 - 5 - 英文原文 FEATURE-BASED COMPONENT MODELS FOR VIRTUAL PROTOTYPING OF HYDRAULIC SYSTERM Abstract: This paper proposes a feature-based approach for the virtual prototyping of hydraulic systems. It presents a framework which allows the designer to develop a virtual hydraulic system prototype in a more intuitive manner, i.e. through assembly of virtual components with engineering data. The approach is based on identifying the data required for the development of the virtual prototypes, and separating the information into behaviour, structural, and product attributes. Suitable representations of these attributes are presented, and the framework for the feature-based virtual prototyping approach is established,based on the hierarchical structure of components in a hydraulic system. The proposed framework not only provides a precise model of the hydraulic prototype but also offers the possibility of designing variation classes of prototypes whose members are derived by changing certain virtual components with different features. Key words: Computer-aided engineering; Fluid power systems;Virtual prototyping 1.Introduction Hydraulic system design can be viewed as a function-to-form transformation process that maps an explicit set of requirements into a physical realisable fluid power system. The process involves three main stages: the functional specification stage,the configuration design stage, and the prototyping stage.The format for the description of the design in each stage is different. The functional specification stage constitutes the initial design work. The objective is to map the design requirements. To achieve this, the design problems are specified Correspondence and offprint requests to: Dr S. C. Fok, Schoool of Mechanical and Production Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798. The designer must identify the performance attributes, which can include pressure, force, speed, and flowrate, with the required properties such as size, cost, safety and operating sequence. performance requirements for each attribute. In this stage, the design is abstracted in terms of the performance attributes with associated values. The objective of the configuration design stage is to synthesise a hydraulic circuit that performs the required functions conforming to the performance standards within defined constraints. A typical hydraulic system is made up of many subsystems. The smallest building block in a subsystem is the standard hydraulic component (such as valves, cylinders,pumps, etc.). Each type of standard component serves a specific elemental function. The design effort in the configuration design stage is fundamentally a search for a set of optimal arrangements of standard components (i.e. hydraulic circuit) to fulfil the functional requirements of the system. Based on this framework, the designers would normally decompose the overall system functions in terms of subfunctions. This will partition the search space and confine the search for smaller hydraulic subcircuits to perform the subfunctions. Computers are often used to support the configuration design process. For example, Kota and Lee devised a graph-based strategy to automate the configuration of hydraulic circuits. After the development of the hydraulic circuits, digital simulation tools are often used to study and evaluate these configurations. With these tools, designers can compare the behaviour of different circuits and also analyse the effects when subcircuits are combined. In the configuration design stage, the design is traditionally represented as a circuit drawing using standard icons to symbolise the type of standard component. This is a form of directed graph S(C,E) where the circuit S contains components C in the form of nodes with relations between components denoted by edges E. The prototyping stage is the verification phase of the system design process where the proposed hydraulic circuit from the configuration design stage is developed and evaluated. Physical prototyping aims to build a physical prototype of the hydraulic system 666 S. C. Fok et al. using industrial available components. The process of physical prototyping involves the following: Search for appropriate standard components from different manufacturers. Pre-evaluation and selection of components based on individual component cost, size, and specification, and compatibility factors between components. Procurement and assembly of the selected components.Test and evaluate the physical prototype based on the overall system requirements. Use other components or redesign the circuit (or subcircuits) if necessary.Besides dynamics, the development of the physical prototype must take into consideration other factors including structure,cost, and weight. The dynamics data are used to confirm the fluid power system behaviour whereas the geometric information is used to examine the assembly properties. The development of the physical prototype will provide the actual performance,structure, and cost of the design. The main disadvantage of physical prototyping is that it is very tedious and time consuming to look for a set of suitable combinations of standard components from among so many manufacturers. Although the basic functions of the same types of standard component from different manufacturers do not differ, their dynamics, structural and cost characteristics may not be similar, because of design variation. Hence, for a given hydraulic circuit, different combinations of parts from different manufacturers can have implications on the resulting system,in terms of dynamics, structure, and cost. Value engineering can be used at this stage to improve the system design by improving the attributes at the component level. This includes maximizing the performance-to-cost ratio and minimising the size-to-performance ratio. Virtual prototyping can be viewed as a computer-aided design process, which employs modelling and simulating tools to address the broad issues of physical layout, operationalconcept, functional specifications, and dynamics analysis under various operating environments. The main advantage of virtual prototyping is that a hydraulic system prototype can be assembled, analysed, and modified using digital computers without the need for physical components, thus saving lead time and cost. The main requirement of a virtual hydraulic system prototype is to provide the same information as a physical prototype for the designer to make decisions.To achieve this, the virtual prototype must provide suitable and comprehensive representations of different data. Furthermore, transformation from one representation to another should proceed formally. Xiang et al. have reviewed the past and current computer-aided design and prototyping tools for fluid power systems. The work revealed that the current tools could not provide a complete representation of the design abstractions at the prototyping stage for design judgement. Most of the tools concentrate on the dynamics behaviour. Vital geometrical and product information that relates to the system prototype consideration and evaluation is frequently missing.To advance the development of computer-aided virtual prototyping tools for fluid power systems, there is a need to address the formal representations of different abstractions of behaviour,structural, and product data along with their integration. This paper focuses on these issues and proposes the formalism of a unified component model and the taxonomy based on the feature-based approach. In Section 2, we discuss the feature- based approach focusing on the key information and their representations required for hydraulic system prototyping. Section 3 presents a formalism of the feature-based model and structure for the development of virtual hydraulic system prototypes.The structure is illustrated with an example. Future work and conclusions are given in Section 4. 2. Feature-Based Approach Features can be defined as information sets that refer to aspects of attributes that can be used in reasoning about the design, engineering or manufacturing processes. The concept of using features to integrate CAD/CAPP/CAM is not new and there are many papers on the application of this approach in CIM. In all these applications, the feature model is regarded as the basis whereas design by features is the key for the integration. To develop a feature model, the relevant information concerning the design must be identified and grouped into sets based on the nature of the information. The relevant information should contain sufficient knowledge for activities such as design, analysis, test, documentation, inspection, and assembly, as well as support various administrative and logistic functions. Design by features is the process of building a model of the design using features as primitive entities. The feature model provides the standardisation of relevant data. Through the design by features approach, vital knowledge of the design will be generated and stored. Together, the feature model and the design by features approach will provide the essential information, which can be used, not only for the simultaneous consideration of many different concerns with the design, but also to interface the many activities in the design realisation process, including the life cycle support operations. The main drawback of the feature-based design approach is that the feature model should be properly defined . This can be difficult, as features are sets of knowledge that are application dependent. The organisation of the features can also be application specific. Non-trivial data-management problems could arise if the feature model is not properly defined. To avoid these problems, the type,representation and structure of the features should be resolved prior to using the feature-based design methodology. The main concern when developing a feature model is that it is application-specific. In the domain of virtual prototyping of hydraulic systems, the details of the constituent standard components must be able to be used to describe the overall system. The component features are bearers of knowledge about that part. To create a suitable feature model for hydraulic system design based on the assembly of standard components, the relevant information associated with various standard components must be identified and classified. This definition Feature-Based Component Models 667 of the component feature set can then be extended to encompass the subsystem feature set based on the hierarchical structure between the components in the subsystem. In the same manner, a hierarchical structure for the hydraulic system feature representation would evolve by considering the system as a hierarchy of subsystems. The necessary information required for a proper description of the virtual prototype must be no less than that derived by the designer from a physical prototype for decision making. These data should generally include the shape, weight, performance properties, cost, dimensions, functionality data, etc. Comparison with the physical prototyping process, the information required for each standard component could be separated into three distinct groups: behaviour attributes, structural attributes, and product attributes. 2.1 Behaviour Attributes The behaviour of a hydraulic component can be defined in terms of the dynamics characteristics used to satisfy the functional requirements. Consider a hydraulic cylinder connected to a load. Its function is to transmit a force from the stroke of the piston to the load. The maximum force it can transmit can be used to define the functionality and the behaviour requirements can be specified in terms of the desired load acceleration characteristics. Hence for a hydraulic component, behaviour attributes express functionality and can be reflected in the dynamics characteristics. The designer is responsible for the proper definition of the overall system behaviour characteristics in terms of the desired dynamics. A standard component will have its own behaviour and provide a specific function.Complex functions that cannot be achieved by a single standard component are derived using a combination of components. Hence, the behaviour of the standard component will play an important role as the individual behaviours of components together with their arrangement can alter the overall system function . The behaviour of a standard component can be nonlinear and can be dependent on the operating conditions. When two components are combined, it is possible that their behaviours can interact and produce undesired or unintended characteristics. These unwanted behaviours are assumed to have been resolved during the configuration design stage. The hydraulic circuit used in the prototyping stage is assumed to be realisable and without any undesirable interacting behaviours. This means that the output behaviour of a component will provide the input to the subsequent component. The representation of behaviours for hydraulic systems has been widely investigated. These representations include transfer functions, state-space and bond graphs. Transfer functions (for single-input–single-output systems) and state-space equations (for multiple-input–multiple-output systems) are based on the approximation of the dynamics about a nominal operating condition. The power bond graph model is based on the causal effects that describe the energy transformations in the hydraulic system. This approach is appealing for hydraulic system analysis. The main disadvantage is that the derivation of the dynamics equation in a bond graph of a complicated fluid power system can become very tedious. As a result, recent work has concentrated on the used of artificial intelligence to represent the nonlinear mapping between the input and output data, which can be obtained via experimental work. These nonlinear mappings can be accomplished using artificial neural networks . It is quite natural for a hydraulic system designer to use input–output data to describe the behaviour of a hydraulic component. The configuration design of a hydraulic system is often achieved through steps of function decomposition. To design a hydraulic system, the designer often tries to decompose the functions and their requirements down to the component level. - 1 -