机械外文文献及翻译.docx

1、机械外文文献及翻译与机械相关的外文及翻译Multidisciplinary Design Optimization of Modular Industrial Robots by Utilizing High Level CAD Templates1、IntroductionIn the design of complex and tightly integrated engineering products, it is essential to be able to handle interactions between different subsystems of multidisci

2、plinary nature 1. To achieve an optimal design, a product must be treated as a complete system instead of developing subsystems independently 2. MDO has been established as a convincing concurrent design optimization technique in development of such complex products 3,4.Furthermore, it has been poin

3、ted out that, regardless of discipline, basically all analyses require information that has to be extracted from a geometry model 5. Hence, according to Bow-cutt 1, in order to enable integrated design analysis and optimization it is of vital importance to be able to integrate an automated parametri

4、c geometry generation system into the design framework. The automated geometry generation is a key enabler for so-called geometry-in-the-loop6 multidisciplinary design frameworks, where the CAD geometries can serve as framework integrators for other engineering tools.To eliminate noncreative work, m

5、ethods for creation and automatic generation of HLCt have been suggested by Tarkian 7.The principle of high HLCts is similar to high level primitives(HLP) suggested by La Rocca and van Tooren 8, with the exception that HLCts are created and utilized in a CAD environment.Otherwise, the basics of both

6、 HLP and HLCt can, as suggested byLa Rocca, be compared to parametric LEGOV Rblocks containing a set of design and analysis parameters. These are produced and stored in libraries, giving engineers or a computer agent the possibility to first topologically select the templates and then modify the mor

7、phology, meaning theshape,of each template parametrically.2、Multidisciplinary Design FrameworkMDO is a “systematic approach to design space exploration”17, the implementation of which allows the designer to map the interdisciplinary relations that exist in a system. In this work, the MDO framework c

8、onsists of a geometry model, a finite element(FE) model, a dynamic model and a basic cost model. The geometry model provides the analysis tools with geometric input. The dynamic model requires mass properties such as mass, center of gravity, and inertia. The FE model needs the meshed geometry of the

9、 robot as well as the force and torque interactions based on results of dynamic simulations.High fidelity models require an extensive evaluation time which has be taken into account. This shortcoming is addressed by applying surrogate models for the FE and the CAD models. The models are briefly pres

10、ented below.2.1 High Level CAD TemplateGeometry ModelTraditionally, parametric CAD is mainly focused on morphological modifications of the geometry. However, there is a limit to morphological parameterization as follows:The geometries cannot be radically modified.Increased geometric complexity great

11、ly increases parameterization complexity.The geometry model of the robot is generated with presaved HLCts, created in CATIA V5. These are topologically instantiated with unique internal design variables. Topological parameterization allows deletion, modification, and addition of geometricelements wh

12、ich leads to a much greater design space captured.Three types of HLCts are used to define the industrial robot topologically; Datum HLCt which includes wireframe references required for placement for the Actuator HLCTs and Structure HLCts, as seen Fig.2.Fig. 2 An industrial robot (left) and a modula

13、r industrial robot(right)The names of the references that must be provided for each HLCt instantiation are stored in the knowledge base (see Appen-dix A.4), which is searched through by the inference engine. In Appendix A, pseudocode examples describes how the references are retrieved and how they a

14、re stored in the knowledge base.The process starts by the user defining the number of degrees of freedom (DOF) of the robot (see Fig. 3) and is repeated until the number of axis (i) is equal to the user defined DOF.In order to instantiate the first Structure HLCt, two Datum and two actuator instance

15、s are needed. References from the two Datum instances help orienting the structure in space, while the geometries of the actuator instances, at both ends of the link, are used to construct the actuator attachments, as seen in Figs. 2 and 3. For the remaining links, only one new instance of both datu

16、m and actuator HLCts are required, since the datum and actuator instances from adjacent links are already available.Appendix A.2 shows a pseudocode example of an instantiation function. The first instantiated datum HLCt is defined with reference to the absolute coordinate system. The remaining datum HLCt instances are placed in a sequential order, where the coordinate system of previous instances is used as reference for defining the