Sanjay Joshi

Graph-based heuristics for recognition of machined features from a 3D solid model

Abstract The internal representation of the solid modeller provides a description of parts which when used directly is useful for automation of the process planning function. So that the CAD model can be used to provide the information required for manufacturing, techniques to improve machine understanding of the part as required for manufacturing are needed. This paper presents the development of the concept attributed adjacency graph (AAG) for the recognition of machined features from a 3D boundary representation of a solid. Current implementation of the feature recogniser is limited to polyhedral features such as pockets, slots, steps, blind steps, blind slots, and polyhedral holes. Sample results that show the capabilities of the system are presented.

Detection of deadlocks in flexible manufacturing cells

One specific problem of control, namely, system deadlock that can arise in an unmanned flexible manufacturing system (FMS) is addressed, and some related work in the deadlocking of computer systems is described. A formal model for manufacturing system deadlock detection is presented. Necessary and sufficient conditions for manufacturing system deadlock based on actual manufacturing-system characteristics are defined along with a set of bounds for searching for deadlocks. An implementation approach is also presented. >

Metamodeling: Radial basis functions, versus polynomials

Abstract For many years, metamodels have been used in simulation to provide approximations to the input–output functions provided by a simulation model. In this paper, metamodels based on radial basis functions are applied to approximate test functions known from the literature. These tests were conducted to gain insights into the behavior of these metamodels, their ease of computation and their ability to capture the shape and minima of the test functions. These metamodels are compared against polynomial metamodels by using surface and contour graphs of the error function (difference between metamodel and the given function) and by evaluating the numerical stability of the required computations. Full factorial and Latin hypercube designs were used to fit the metamodels. Graphical and statistical methods were used to analyze the test results. Factorial designs were generally more successful for fitting the test functions as compared to Latin hypercube designs. Radial basis function metamodels using factorial and Latin hypercube designs provided better fit than polynomial metamodels using full factorial designs.

Recognizing multiple interpretations of interacting machining features

Abstract A new feature recognition algorithm capable of recognizing interacting machining features and providing multiple interpretations is presented. For machined parts with interacting features, multiple equally valid sets of feature interpretations exist. The term ‘multiple interpretations’ is associated with identifying all the possible sets of machining features that can be recognized from the part. It represents multiple ways to decompose the total machinable volume into feature volumes. The feature recognition algorithm presented in the paper uses a boundary representation as input, and it is developed in two stages: (a) volume decomposition, and (b) reconstruction of features. In the first stage, the volume to be machined is identified and decomposed into small blocks by extending boundary faces of the part. In the second stage, feature volumes are reconstructed by systematically connecting the small blocks built in the previous stage. The current algorithm is capable of recognizing certain classes of interacting prismatic depression features, such as slots, steps, blind slots, blind steps, pockets, and prismatic holes, and it provides multiple interpretations. Test software is implemented and integrated with the i-deas solid modeller. Sample results demonstrating the algorithm are also presented.

Resolution of deadlocks in flexible manufacturing systems: Avoidance and recovery approaches

Abstract One problem that has often been overlooked in research in flexible manufacturing systems (FMSs) design and operation is deadlocking. An FMS deadlock is a situation where machines have been allocated parts so that further part movement is inhibited. In our earlier paper, a procedure to detect deadlocks was presented. In this paper, two approaches to resolve deadlock problems, namely avoidance and recovery, are presented and analyzed. These approaches can be used to avoid or resolve deadlocks during active control of the FMS. A simulation study to compare deadlock resolution approaches to conventional approaches for avoiding deadlocks is also presented. Results of the analysis are presented.

Feature extraction and feature based design approaches in the development of design interface for process planning

The quest for completely automated process planning systems has exposed the lack of techniques capable of automatically understanding the stored CAD models in a manner suitable for process planning. Most current generations of process planning systems have used the ability of humans to translate the part drawing requirements into a form suitable for computer aided process planing. Recently, research advances have been made to improve the understanding of computer stored 3-D part models. The two approaches used are feature recognition and feature based design. This paper presents a state of the art review of feature recognition techniques developed and presents feature based design as an alternative. Process planning systems developed using both approaches are presented.

Expert systems in industrial engineering

An expert system can be denned as ‘a tool which has the capability to understand problem specific knowledge and use the domain knowledge intelligently to suggest alternate paths of action’. This paper presents a structured framework for the development of an expert system. The five major aspects of expert system development are: Problem definition; knowledge acquisition, representation and coordination; inference mechanism; implementation; and learning. These aspects are illustrated through the help pf a modular robot configuration prototype expert system. Several industrial engineering applications in the areas of process planning, facilities planning, and maintenance and fault diagnosis are discussed and a comparative analysis of the different systems is presented.

Error compensation for fused deposition modeling (FDM) machine by correcting slice files

Purpose – The purpose of this research is to extend the previous approach to software error compensation to fused deposition modeling (FDM) machines and explores the approach to apply compensation by correcting slice files.Design/methodology/approach – In addition to applying the stereolithography (STL) file‐based compensation method from earlier research; a new approach using the slice file format to apply compensation is presented. Under this approach, the confounded effects of all errors in a FDM machine are mapped into a “virtual” parametric machine error model. A 3D artifact is built on the FDM machine and differences between its actual and nominal dimensions are used to estimate the coefficients of the error functions. A slice file compensation method is developed and tested on two types of parts as a means for further improving the error compensation for feature form error improvement. STL file compensation is also applied to a specific FDM 3000 machine and the results are compared with those of a ...

Auction-based distributed scheduling in a dynamic job shop environment

Developments in computing and communication technology coupled with the inability to address real-time issues in scheduling algorithms based on central control, has led to an interest in solving the problem of a distributed decision-making environment. This paper presents a new job shop formulation that schedules jobs using auctions for distributing control. A theoretical basis is presented for problem decomposition, bid construction, and bid evaluation for the auction using standard mathematical programming tools. Numerical results show that the auction-based approach outperforms the distributed dispatching approaches and can be used to create schedules for a wide range of scheduling objectives.

Formal models for control of flexible manufacturing cells: physical and system model

Most control implementations of flexible manufacturing cells have been developed specific to a particular facility, and no generic format or tools exist for the systematic planning and creation of control. This paper presents the first phase of research in automatic generation of control software. It focuses on the development of theoretical foundations and generic issues necessary to understand and implement control. Specific formal models are developed for the physical activities, system actions, and individual machines comprising the manufacturing cell. In a subsequent paper, the formal models presented here are used to provide the basis for creating context free control grammars which are used to automatically generate software for controlling flexible manufacturing cells. >