http:^^www.cs.utah.edu^projects^robot^virtual_prototyping.html
来自「This data set contains WWW-pages collect」· HTML 代码 · 共 214 行
HTML
214 行
Date: Tue, 14 Jan 1997 19:35:44 GMT
Server: Apache/1.1.1+
Content-type: text/html
Content-length: 7743
Last-modified: Tue, 14 Jan 1997 18:34:21 GMT
<html><head><TITLE> Virtual Prototyping of Mechanical Assemblies </TITLE></head><body background="IMAGES/back-nice.gif" text="#000000"><center><h2>Virtual Prototyping of Mechanical Assemblies</h2></center><p><center> <!WA0><img src= "http://www.cs.utah.edu/projects/robot/IMAGES/vp-slave-mesh-180H.gif"> <!WA1><img src= "http://www.cs.utah.edu/projects/robot/IMAGES/arches.gif"> <!WA2><img src= "http://www.cs.utah.edu/projects/robot/IMAGES/sda-master-tom.gif"></center><P>Current generation CAD systems provide little support for prototypingmechanical assemblies. We arecreating an integrated design and simulation system to address thisproblem. Fundamental to the effort is the investigation of effectivemechanisms for allowing a designer to interact with an assembly ofparts in a ``virtual'' manner, prior to creation of any physicalprototypes. The designer will be able to touch, hold, and move modelsof parts and assemblies as well as see them in rendered views. Theresult will be an environment in which part interactions can beconsidered in a more natural manner than is possible with currenttechnology. Part interactions and articulations of high DOF assembliescan be considered early in the design process. Assembly procedures canbe evaluated at the time when parts are designed, without the need toexplicitly specify assembly sequences or constraints. Even greateradvantages will accrue in the design of devices intended for human use,since manipulability can be examined without the need to fabricate aphysical prototype. Finally, the virtual display tools that areintegral to this project will give designers a better appreciation forcomplex part geometry than can be gained from traditional CAD displays,which have only limited 3-D information. </p><center><!WA3><IMG SRC ="http://www.cs.utah.edu/projects/robot/IMAGES/bar_color.gif"></center><center><table border="0" cellpadding="10"><td width="40%" align="left" valign="top"><H3> Faculty </H3><UL> <li> <!WA4><a href = "http://www.cs.utah.edu/~jmh"> John M. Hollerbach</a>, PI <li> <!WA5><a href = "http://www.cs.utah.edu/~cohen"> Elaine Cohen</a> <li> <!WA6><a href = "http://www.sarcos.com/Jacobsen.html">Stephen C. Jacobsen</a> <li> <!WA7><a href = "http://www.cs.utah.edu/~thompson"> William B. Thompson</a></UL></td><td width="25%" align="left" valign="top"><H3> Staff </H3><UL> <li> <!WA8><a href = "http://www.cs.utah.edu/~fish"> Russ Fish</a></UL></td><td width="35%" align="left" valign="top"><H3> Graduate Students</H3><UL> <li> <!WA9><a href = "http://www.cs.utah.edu/~freier"> Rodney Freier</a> <li> <!WA10><a href = "http://www.cs.utah.edu/~dejohnso"> David Johnson </a> <li> <!WA11><a href = "http://www.cs.utah.edu/~nahvi"> Ali Nahvi</a> <li> <!WA12><a href = "http://www.cs.utah.edu/~dnelson"> Donald Nelson</a> <li> <!WA13><a href = "http://www.cs.utah.edu/~tthompso"> Thomas Thompson</a></UL></td></tr></table></center><center><!WA14><IMG SRC ="http://www.cs.utah.edu/projects/robot/IMAGES/bar_color.gif"></center><p>CAD systems for all but the simplest of mechanical parts must be ableto provide the designer with a clear sense of three-dimensional objectgeometry. Usually this is done with standard graphical renderingtechniques involving perspective, shading, and simple animation. Whensuch tools are used for assemblies of parts, we often hear designerscomplain: ``What I really want to do is get my hands on the parts andsee how they fit together.'' In fact what is happening is that theconventional display technologies are not providing the user withsufficient information about the geometry and manipulability of theobjects in question.<P>A key aspect of addressing this limitation is to augment visualrendering of geometric models with haptic interfaces which allow directmanipulation of modeled objects. Such interfaces must include accurateanthropomorphic geometry and provide realistic force feedback if theyare to be of real value. The Sarcos Dextrous Arm Master representsarguably the most advanced force-reflecting exoskeleton availabletoday. The upper seven degree-of-freedom arm component matches theredundancy of the human arm, while three degrees of freedom areprovided to the hand; in total, there are 10 degrees of freedom and offorce reflection per master arm. In the hand, there is a twodegree-of-freedom thumb, a fixed forefinger, and a onedegree-of-freedom flexing index/middle finger. The Sarcos Dextrous Armis based on hydraulic actuation, which is unmatched for torque densityand bandwidth for this application. The result is a master that ismuch more compact and of higher performance than would be possible withelectric motor drives.<P><center> <!WA15><img src= "http://www.cs.utah.edu/projects/robot/IMAGES/real-engine.gif"> <!WA16><img src= "http://www.cs.utah.edu/projects/robot/IMAGES/gear-chain-2.gif"></center><P>The pictures above shows a one third scale model for a novel dieselengine with one cylinder, two pistons, and four crankshafts andrepresents of the kinds of assemblies that we are working towardsaccommodating in a virtual prototyping system. The engine involvescomplex and interrelated part motions that should be well understood bydesigners prior to committing to expensive fabrication operations. Afull-function virtual prototyping system will let the designermanipulate individual parts to see how the entire assembly moves.Virtual prototyping furthermore would allow a designer to considerpossible assembly sequences, modifying parts as necessary to ease theassembly process. Finally, a virtual prototyping system with asufficiently complete model of the human body could be used to validateassembly operations for the engine.<P>Creating a user interface for virtual prototyping systemsinvolves solving three largely independent problems: <UL><li><EM>Visual rendering</EM>involves creating realistic views of a configuration of parts.<li>There are two aspects to <EM>haptic rendering</EM>. The firstinvolves giving the user a realistic sensation that he or she isactually touching and manipulating physical objects. The second takesmotions made by a user and modifies the models specifying the virtualworld appropriately. <li><EM>Contact and interference</EM> computations areneeded to determine part-to-part and user-to-part interactions in thevirtual world. Visual rendering, haptic rendering, and contact andinterference detection must all exploit knowledge about the nature ofmechanical assemblies, since general solutions are not likely to beviable.</UL>Geometric modeling systems able to support virtual prototyping ofmechanical assemblies need capabilities beyond those of the typicalCAD/CAM system. Not only must it be possible to design and renderindividual parts, but part interactions involving contact, forces, andtorques must be computable in real-time. When a designer reaches outto ``grab'' a (virtual) part, the system needs to know when contactwith the part has been made so that appropriate feedback can begenerated. Once a solid grip has been established, user feedback mustreflect object inertial and gravity forces and assembly forces due tocontact. For those assemblies capable of articulation, a manipulationof one part of the assembly must both cause the appropriate motions inother parts of the assembly and reflect appropriate sensations to theuser.<P><center> <!WA17><img src= "http://www.cs.utah.edu/projects/robot/IMAGES/haptic-requirements.gif"></center><P>Standard CAD systems are unable to supply much of the informationneeded to support either assembly operations themselves or the hapticrendering required in a virtual prototyping system.<p><br><hr><center><nobr><!WA18><a href="http://www.cs.utah.edu/projects/robot//"><!WA19><img border=0 src="http://www.cs.utah.edu/projects/icons/dept_cs_button.gif"></a><!WA20><a href="http://www.cs.utah.edu/projects/"><!WA21><img border=0src="http://www.cs.utah.edu/projects/icons/research_cs_button.gif"></a><!WA22><a href="http://www.cs.utah.edu/projects/robot"> <!WA23><img border=0 src="http://www.cs.utah.edu/projects/icons/vis-rob_cs_button.gif"></a><!WA24><a href="http://www.cs.utah.edu/projects/alpha1"> <!WA25><img border=0 src="http://www.cs.utah.edu/projects/icons/alpha1_cs_button.gif"></a></nobr></center><hr><!--<address><!WA26><a href ="mailto:vision@hayduke.cs.utah.edu">vision@hayduke.cs.utah.edu</a><br>--></BODY></html>⌨️ 快捷键说明
复制代码Ctrl + C
搜索代码Ctrl + F
全屏模式F11
增大字号Ctrl + =
减小字号Ctrl + -
显示快捷键?