Variable Focus Three-Dimensional Laser Digitizing System

This paper describes a new three-dimensional scanning technology which is being developed at Colorado State University. Unlike other laser-based scanners which use active or passive triangulation to obtain surface range data, the new variable focus laser digitizing system (VFLDS) uses the principles of optical focal length to measure surface range data. This system should represent a significant step forward in speed and simplicity over current laser-based single point digitizing systems while retaining all of their advantages. The goal of the initial research presented here is to produce preliminary results which will prove the viability of this new approach.

A Hybrid Fuzzy Controller for Industrial Power Plants

The automation of the control to a power plant is indeed a challenge mainly because of the occurrences of random and unpredictable variations in output demands as well as because of highly non-linear behavior of the system itself [1]. It is sometimes argued that the ‘best’ control for a power plant is the operators themselves. Experienced operators are capable of taking decisions on the basis of incomplete and imprecise information. The extent to which these decisions are correct is a matter of speculation. Erroneous conclusions, established post facto, are chalked up to the learning process and in fact, contribute to the forming of a good, experienced control team. The need to automate the control process for a plant is even more acutely felt when considering the complexity of the plants themselves and the volume of data that would have to be processed before a control decision can be taken. Factored into this decision would also be several governing parameters such as costs, reliability, other constraints and their interdependancy, as well as planned and unscheduled outages for maintenance and so on. In this paper, however, only one facet of a power plant operation is considered. It is intended to demonstrate that thermal efficiency may be improved by better techniques for automated control of throttle valves in the steam turbine of the plant. One of these options, fuzzy logic, is selected, and defended, as being the more effective than current techniques. A comparative analysis is conducted of control techniques for plant operations followed by a brief overview of fuzzy control and its application to control of non-linear systems. A method of applying this ‘new’ computer-based technique to control of non-linear, somewhat erratic plants is presented and discussed.

The Significance of Specifications in the Product Development Processes

An approach to support the appropriate definition, formulation and presentation of requirements obeying the needs of the employees is being presented. Classifiying the needs for information of the employees according to some characteristics, a guideline for how to promote the information needed by them can be developed. The goal is to ensure that everyone involved in the process — even the subcontractor — has the right information available in the right form at the right time. Defining requirements lists, splitting them into partial requirements lists for each area of the company, each process phase or each team, and then formulating these requirements and presenting them in an adequate way is the proceeding strived for. The result will be implemented into an information infrastructure to support the product development process continuously.

A Unifying Version Model for Object-Oriented Engineering Database

Versioning has been one of the important requirements for engineering design databases and is of increasing interest to database system designers. While there exist many object-oriented DBMS’s that support various versioning facilities, these systems consider the versioning problems as two separate domains: object versioning and schema versioning. In this paper, we consider both domains together and propose a unifying version model for both objects and schema. In particular, we present how we unify version controls for schema and objects, and describe issues in implementation.

COVIRDS: A Conceptual Virtual Design System

This paper describes the development of a computer system architecture for mechanical conceptual shape design within a virtual environment — COVIRDS1 (COnceptual VIRtual Design System).

Maximal Volume Decomposition and its Application to Feature Recognition

A method has been developed that decomposes an object having both planar and curved faces into volumes, called maximal volumes, using the halfspaces of the object. A maximal volume has as few concave edges as possible without introducing additional halfspaces. The object is first decomposed into minimal cells by extending the faces of the object. These minimal cells are then composed to form maximal volumes. The combinations of such minimal cells that result in maximal volumes are searched efficiently by examining the relationships among those minimal cells. With this decomposition method, a delta volume, which is the volume difference between the raw material and the finished part, is decomposed into maximal volumes. By subtracting maximal volumes from each other in different orders and applying graph matching to the resulting volumes, multiple interpretations of features can be generated.

Feature-Based 3-D Sketching for Early Stage Design

During early stages of design, the mere presence of items, their relative positioning, and their interrelationships can be more significant than fine details, like exact dimensions, whether a hole is counterbored, or the exact cross-sectional shape of a groove. Most CAD systems have little, if any, support for this critical, incipient design stage, In addressing this economically compelling and highly leveraged area, we present an intuitive, feature-based approach to 3-D design which permits a complete first pass through the design-manufacturing cycle even before a detailed specification is complete. We report a functioning 3-D design front-end for a solid modeling system that has been used for fast intra-part and inter-part, visual, generalized feature specification, a frontend that is intimately connected to the system so that both visual and detailed design can be carried out concurrently on the same model to meet designer needs. Hence, the design that is “captured” during the sketch and modify phase using this approach is fully usable for activities that traditionally require a fully detailed solid model, such as rendering, finite element and other analysis, assembly analysis, process planning, and manufacturing at this initial stage instead of the traditionally late stages.

Combination of Management Methods and Information Technologies for Product Development Processes

As companies become aware that they have to restructure their product development processes to survive global competition in the market, it is important that they evaluate which management methods and techniques are suitable to improve the performance of the process and which design methods can be integrated and be used efficiently. A combination of management methods like Total Quality Management (TQM), Simultaneous or Concurrent Engineering, and Lean Development can be adapted to meet the requirements of a company more than a single strategy. Interdisciplinary teamwork, cross-hierarchical communication, and delegation of work in addition to employee motivation changes the common attitude towards the work process in the company and integrates the staff more tightly into the process. Nowadays, there is tight cooperation between companies and their sub-contractors, as sub-contractors not only have to manufacture the part or sub-assembly, but often have to design it. Therefore, the product development process has to be defined in a way that the sub-contractors can be tightly integrated into the product development process. Additionally, it is important to break the product down into functionally separate modules during the conceptual phase of the process. If the interfaces between these functions are defined as specifications, these modules can easily be given to suppliers or to other teams inside the company for further development. The use of methods such as Design for Manufacture (DFM) or Design for Assembly (DFA) early during the development process, which utilize the knowledge of experts from manufacturing and assembly, results in a decreasing number of iterative loops during the design process and therefore reduces time-to-market. This cross-functional cooperation leads to improved quality of both processes and products. In this paper, different management methods to achieve the best improvement from the product development process are discussed. In addition, suitable design methods for achieving cost reduction, quality improvement, and reduction of time-to-market are presented. Finally, proposals for industry on methods to reorganize the Integrated Product Development (IPD) process based on actual findings are presented.

Cutting Path and Feedrate Optimization for Complex Surface Machining Using Ball End Milling Process

A new machining strategy, called cutting-path/adaptive-feedrate strategy, is proposed to improve the productivity of sculptured-surface productions subjected to force and dimensional constraints. In this proposed strategy, a new machining-planning aid, called maximum feedrate map, is developed. In this map, the maximum allowable feedrates at each control point along all machining directions subjected to the specified constraints are determined using a surface generation model. These local maximum-feedrate boundaries indicate the acceptable range of feedrates that a part programmer can use in the NC programming. In addition, the maximum feedrate map also provides the part programmer an important aid in selecting the cutting directions. The proposed strategy was applied to the machining planning for turbine blade die productions. Both computer simulation and experimental study were performed.

Geometric Reasoning for the Coding of CAD Models

Many of today’s concurrent product-development cycles depend on the utilization of intelligent Computer-Aided Design (CAD) systems. Thus, it would be essential to provide CAD users with effective means for interacting with the CAD system and its database. This paper addresses the development of a boundary-based coding procedure for CAD models. Coding the geometric and processing characteristics of objects, based on their CAD model representation, has been long recognized as an effective approach that allows convenient design retrieval on the one hand and process-planning automation on the other. Our work is based on the assumption that form features are recognizable and extractable from the CAD model by current feature-recognition, feature extraction and feature-based-design approaches. The coding procedure is applicable to the boundary representation of the object and its extracted form features.