Commercially Available Computer-aided Design Research Articles

Determination of geometric information and radiation field overlaps on the skin in percutaneous coronary interventions with computer-aided design-based X-ray beam modeling.

PurposeThis study aimed to develop a method for the determination of the source‐to‐surface distance (SSD), the X‐ray beam area in a plane perpendicular to the beam axis at the entrance skin surface (Ap ), and the X‐ray beam area on the actual skin surface (As ) during percutaneous coronary intervention (PCI).Materials and MethodsMale and female anthropomorphic phantoms were scanned on a computed tomography scanner, and the data were transferred to a commercially available computer‐aided design (CAD) software. A cardiovascular angiography system with a 200 × 200 mm flat‐panel detector with a field‐of‐view of 175 × 175 mm was modeled with the CAD software. Both phantoms were independently placed on 40 mm thick pads, and the examination tabletop at the patient entrance reference point. Upon panning, the heart center was aligned to the central beam axis. The SSD, Ap , and As were determined with the measurement tool and Boolean intersection operations at 10 gantry angulations.ResultsThe means and standard deviations of the SSD, Ap , and As for the male and female phantoms were 573 ± 15 and 580 ± 15 mm, 8799 ± 1009 and 9661 ± 1152 mm2, 10495 ± 602 and 11913 ± 600 mm2, respectively. The number of As overlaps for the male and female phantoms were 15/45 and 21/45 view combinations, respectively.ConclusionsCAD‐based X‐ray beam modeling is useful for the determination of the SSD, Ap , and As . Furthermore, the knowledge of the As distribution helps to reduce the As overlap in PCI.

Phase Shifting Properties of High-Pass and Low-Pass Mixed-Element Two-Ports

In many applications, circuits containing lumped-elements are preferred because of their small sizes. But it is not possible to avoid losses caused by the connections between lumped-elements at high frequencies. However, the use of these connections as circuit elements will improve the performance of the circuit. Therefore, it becomes inevitable to use circuits with mixed (lumped and distributed) elements at high frequencies. In this brief, phase shifting properties of high-pass and low-pass mixed-element two-ports is explained. Then these two-ports are used to form the initial design of high-pass and low-pass sections of a phase shifter. Finally, the initial design performance can be improved by means of commercially available computer-aided design (CAD) tools.

Representation of model for efficient collision detection in virtual reality environment

In conceptual design, virtual reality assurances to be a natural, cost-effective, and creative method. Representation of the model in the virtual reality environment is a significant step. In the virtual environment, while representing the model, it should behave realistically. Several techniques like implicit, tessellated, parametric representations are available for representing the models. In the present work, the model is created from data of point cloud using volumetric self-organising feature map algorithm. The virtual model generation from point cloud data helps in the secure exchange of database between commercially available computer-aided design (CAD) software. 3D B-splines have been selected to represent the virtual model. A three-dimensional virtual model has been generated from the data of point cloud. For efficient collision detection, surfaces have been also extracted from the three-dimensional model by considering the alternative values of u, v, w parameters as 0 and 1. Anyone of the six extracted surfaces can be used for collision detection. The results showed that the extraction of surfaces is beneficial for efficient collision detection.

Design of Practical Broadband Matching Networks With Lumped Elements

It is always preferable to use commercially available software tools to design broadband matching networks for microwave communication systems. However, for these tools, the matching network topology and element values must be selected properly. Therefore, in this paper, a practical method is presented to generate matching networks with good initial element values. Eventually, the performance of the designed matching network is optimized by employing the commercially available computer-aided design (CAD) tools. An example is given to illustrate the utilization of the proposed method. It is shown that the proposed method provides very good initials for CAD tools.

Setup Planning Automation for Six-Axis Wire Electrical Discharge Machining

A modern six-axis wire electrical discharge machining (WEDM) system is capable of producing more complex geometries than 2D, 2½D, or ruled surface parts. The rotational axis on a six-axis WEDM system allows a part to be rotated while using a cutting wire to fabricate it. However, limited automation for process planning six-axis WEDM systems requires significant time and effort must be put into process planning. Even with commercially-available computer-aided design (CAD) software, it is difficult to produce process plans for a six-axis WEDM system. Toward automatic development of process plans, a method of determining such setup plans, including the number of setup orientations and rotational axis movements, is presented in this paper. Tangent visibility analysis results presented in our prior research are used to guide the setup, and intermediate coordinate systems are defined in order to classify the tangent visibility results. A greedy algorithm is developed to determine the set of intermediate coordinates and setup orientations for six-axis WEDM.

Design of broadband single matching networks

In general commercially available software tools are preferred, to design broadband matching networks for wireless communication systems. But they need a properly selected matching network topology with good initial element values. Therefore, in this paper a new real frequency technique is presented, to generate broadband single matching networks with suitable initial element values. In the proposed method, load impedance is written in terms of ABCD-parameters of the desired matching network and the source resistor. Then, free parameters are optimized which in turn yields the desired matching network with initial element values. It is not needed to select a circuit topology for the matching network, which is the natural consequence of the matching processes. Also, there is no need to select the desired transducer power gain level; the proposed technique naturally provides a gain curve fluctuating around the final available level. Eventually, the initial design is improved by optimizing the performance of the matched system employing the commercially available computer-aided design (CAD) packages. An algorithm and two examples are given, to illustrate the utilization of the proposed technique.

Transfer of Architectural Data from the IFC Building Product Model to a Fire Simulation Software Tool

A standardized, object-oriented building product model for buildings is introduced that can be used as a means of electronic exchange between various software tools. The ability to transfer architectural data between a commercially available computer-aided design (CAD) program and a widely available zone fire simulation tool illustrates the applicability of this model in fire engineering. This article describes the software developed to interpret the building product model and the test buildings used to verify the exchange process. In general the building geometry, topology, and other properties can be transferred satisfactorily but some inconsistencies exist due to the structure of the building product model, the CAD implementation of the model, and the simplifications required by the zone modeling approach.

Design of Practical Matching Networks With Lumped Elements Via Modeling

It is a common practice to utilize commercially available software tools to design matching networks for wireless communication systems. Most of these tools require a properly selected matching network topology with good initial element values. Therefore, in this paper, a practical method is presented to generate matching networks with initial element values. In the implementation process of the proposed method first, the driving point immitance data for the matching network is obtained in a straight forward manner without optimization. Then, it is modeled as a realizable bounded-real input reflection coefficient which in turn yields the desired matching network with reasonable element values. Eventually, the initial design is improved by optimizing the performance of the matched system employing the commercially available computer-aided design (CAD) packages. An example is given to illustrate the utilization of the proposed method. It is shown that new method provides excellent results as a front-end when utilized together with CAD tools.

Bias-dependent small-signal modeling of GaAs PIN diodes

A new bias-dependent small-signal GaAs PIN diode model is described that is suitable for use in design of circuits like variable attenuators and limiters. The equivalent circuit parameters are extracted from bias-dependent S-parameters measured from 1 to 26 GHz for 35 bias currents. Bias-dependent equations are then curve fitted, and then incorporated into a commercially available computer-aided design (CAD) simulator. Measured and modeled data track each other very well over a range of bias conditions. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 99–106, 2001.

Practical prototyping

The design of robotic mechanisms is a complex process involving geometric, kinematic, dynamic, tolerance, and stress analyses. In the design of a real system, the construction of a physical prototype is often considered. Indeed, a physical prototype helps the designer to identify the fundamental characteristics and the potential pitfalls of the proposed architecture. However, the design and fabrication of a prototype using traditional techniques is rather long, tedious, and costly. In this context, the availability of rapid prototyping machines can be exploited in order to allow designers of robotic mechanisms to build prototypes rapidly and at a low cost. In the article, the rapid prototyping of mechanisms using a commercially available computer-aided design (CAD) package and a fused deposition modeling (FDM) rapid prototyping machine is presented. A database of lower kinematic pairs (joints) is developed using the CAD package, and parameters of fabrication are determined experimentally for each of the joints. These joints are then used in the design of the prototypes where the links are developed and adapted to the particular geometries of the mechanisms to be built. Also, a procedure is developed to build gears and Geneva mechanisms. Examples of mechanisms are then studied and their design is presented. For each mechanism, the joints are described and the design of the links is discussed. Some of the physical prototypes built using the FDM rapid prototyping machine are shown.

A CAD-Based hierarchical approach to interference detection among fixture modules in a reconfigurable fixturing system

A reconfigurable fixturing system has been developed for a computer-integrated assembly environment. The fixturing system employs a number of fixture modules which are set-up, adjusted and changed automatically by the assembly robot. A dedicated software program has been developed for the design, analysis, and verification of the fixture layout. The software program has been integrated with a commercially available computer-aided design (CAD) package to provide a user-friendly platform for modeling and display purposes. The robot program for setting up, adjusting, and dismantling the designed fixture is generated automatically. Interference between fixture modules during the fixture construction may arise due to incorrect selection of the fixture contact points at the design stage. The objective of the work described here is to develop a hierarchical approach for calculation of interference between fixture modules in a reconfigurable fixturing system. The formulation for the interference detection employs geometrical constraints as the basis. The approach does not require detailed simulation of the fixture construction for interference detection.

Experimental investigation of the performance of a reconfigurable fixturing system

A reconfigurable fixturing system has been developed for computer-integrated assembly environments. The fixturing system employs a number of fixture modules that are set-up, adjusted and changed automatically by the assembly robot without human intervention. A commercially available computer-aided design (CAD) package with the help of a dedicated software program is used for the design, analysis, and verification of the fixture layout. The robot program for setting-up, adjusting, and dismantling the designed fixture is generated automatically. This paper presents and discusses the accuracy of such a reconfigurable fixturing system in view of the off-line programming techniques. The experimental techniques to measure the accuracy and repeatability for setting-up the fixture are presented. The measured results of the robot positioning various types of locating fixture modules are presented and compared with the intended position settings. From the comparison, the accuracy that is to be expected from such an approach to fixturing and measures for improvement are discussed. The cycle times involved in setting-up the fixture modules are also presented and analysed. These results provide an initial guide for manufacturing industries interested in employing such systems in their computer-integrated assembly environment.

CAD-based design and analysis system for reconfigurable fixtures in robotic assembly

Fixturing is an important requirement for many manufacturing and assembly operations. If flexible manufacturing and assembly systems (FMS and FAS) are to be truly flexible, then the fixturing must also be flexible. This article presents a system for computer-aided design and analysis of reconfigurable fixtures in robotic assembly. The fixturing system employs a number of adjustable fixture modules that are set up, adjusted and changed automatically by the assembly robot without human intervention. The design of the fixture layout is performed interactively on a commercially available computer-aided design (CAD) package. The development of a dedicated software program to perform kinematic analysis of the fixture layout, using the information retrieved from the CAD database, is presented. A strategy to build various fixture layouts to locate and hold workpieces of various shapes and sizes using the same set of fixture modules is also presented.

Issues in the design of the reconfigurable fixture modules for robotic assembly

Abstract Workpiece positioning and constraining is an important factor in manufacturing processes such as machining, welding, bonding, and assembly. Jigs and fixtures are devices employed to position and constrain the workpiece in a desired location to ensure that it is in a state of static equilibrium and that dimensional accuracy is maintained during the manufacturing operation. Traditionally, fixtures have been designed and manufactured as single-purpose devices for specific parts and manufacturing operations. The traditional approach is costly due to the long load time and effort required to design and manufacture special-purpose fixtures, manual set-up and change of fixtures, and overhead cost associated with storing and retrieving a multiplicity of fixtures. Thus, the traditional approach is not suited to the flexible manufacturing environment where production volume is low and product variation is high. If flexible manufacturing systems (FMSs) are to be truly flexible, then the fixturing must also be flexible. This paper presents requirements, design principles, design rules, and a prototype system for flexible fixtures in robotic assembly. Such a fixturing system would employ a number of fixture modules that are set-up, adjusted and changed automatically by the assembly robot without human intervention. The design of the fixture layout is performed interactively on a commercially available computer-aided design (CAD) package. The guidelines for development of a dedicated software program to automatically generate robot program for setting up, adjusting, and dismantling the fixture, using the information retrieved from the CAD database, is presented.