Prashant Banerjee

A comparative study of radio frequency-based indoor location sensing systems

The growing popularity and use of the radio frequency (RF) in different applications, predominantly in the area of identification and location aware system, has driven many researchers. Versatile qualities, easy availability and simplicity of use have led a spate of development of different systems and technologies based on radio frequency identification (RFID). This paper is an attempt to survey the current research work and the commercially available indoor location aware systems using radio frequency. It compares the leading researches in this area and analyzes them on the four basic criteria.

Virtual reality interfaces for feature-based computer-aided design systems☆

Abstract A computer-aided design ( cad ) system with a virtual reality (VR) interface simplifies the design of complex mechanical parts. To add a design feature (e.g., a hole, slot, or protrusion), the designer can navigate in the part to the appropriate face of the part where he/she wishes to attach the feature, and sketch directly on that face. Besides convenience, this method of feature specification implicitly enforces feature accessibility constraints, and also provides hints to the process-planner regarding the order in which the features may be manufactured. We detail the design of a VR-based prototype cad system. The system maintains the knowledge of part cavities and their adjacencies, and a triangulated boundary-representation of an approximating polyhedron. We present incremental provably correct algorithms for updating this representation as the user edits the part. We also show how this representation supports real-time displays, navigation, and collision detection. The user-interface of the cad system relies on these capabilities to provide the above-mentioned advantages.

Assembly Planning Effectiveness Using Virtual Reality

Planning the sequence of components (or parts) to be assembled during manufacturing is an important application problem for virtual environments for three main reasons. First, it is a difficult combinatorial optimization but a highly visual problem. Second, a majority of assembly operations in factories (with the exception of simple pick-and-place operations) are still performed manually, because they are difficult to automate. Hence, it is an important problem involving human-machine interface. Third, there are a number of assembly operations which require dextrous operator training. Hence, it is also an important training problem. Recent research suggests a promising approach for assembly determination based on using heuristic rules to generate soft constraints in addition to the regular hard quantitative constraints due to part geometry and topology. We believe that the emergence of virtual environments can enable us to systematically use these soft constraints, which previously has not been possible. In this paper, we report results of experiments involving fifteen voluntary participants using a nonvirtual reality (VR) environment involving blueprints, a nonimmersive desktop VR environment, and an immersive projection-based VR environment to first teach participants skills in handling soft and hard constraints for assembly planning through examples, and then to measure the effectiveness of their learnt skills in solving a different example problem. We have classified soft constraints as infeasibility constraints, reorientation constraints, difficulty constraints, instability constraints, and dissimilarity constraints. A significant observation is that the participants could, on average, perform the assembly operations in approximately half the time in the immersive and nonimmersive VR environments than in the traditional environment using blueprints.

A Linear Programming Solution for Exact Collision Detection

This paper addresses the issue of real-time collision detection between pairs of convex polyhedral objects undergoing fast rotational and translational motions. Accurate contact information between objects in virtual reality based simulations such as product design, assembly analysis, performance testing and ergonomic analysis of products are critical factors to explore when desired realism is to be achieved. For this purpose, fast, accurate and robust collision detection algorithms are required. The method described in the text models the exact collision detection problem between convex objects as a linear program. One of the strengths of the proposed methodology is its capability of addressing high speed interframe collision. In addition to the interframe collision detection, experimental data demonstrate that mathematical programming approaches offer promising results in terms of speed and robustness as well. DOI: 10.1115/1.1846053

Data input model for virtual reality-aided facility layout

An approach to automatically extract three dimensional (3D) models (that is, geometries and topologies) of physical objects in a facility is described. The rationale for this work is its repeated use in efficiently developing databases of 3D objects for applying virtual reality (VR) tools in detailed layout decision support. Obtaining 3D object models can be a challenging task. Sometimes they are available, for example, in a Computer-Aided Design (CAD) database and these can be readily imported into a VR database. But on many occasions one is not so fortunate and these object models have to be created in correlation to an existing or proposed facility, which can be an extremely tedious and time consuming task. A time efficient and economical alternative is to use video camera images, but quickly and accurately capturing the depth information from 2D camera images has so far remained elusive because the existing methodologies are too general purpose and operate at a lower level of abstraction, namely digitized images. We have developed a method for directly inputting 3D objects into VR-aided facility layout models, by integrating the strengths of previously tried and tested technological components: (i) camera calibration; (ii) image processing; (iii) stereo vision; and (iv) Delaunay triangulation. The techniques described here are embedded in a prototype architecture and toolkit called MIRRORS (Methodology for Inputting Raw Recordings into 3D Object Renderings for Stereo). The primary contribution of this paper is that it has been able to design an integrated system to build 3D object models from 2D images. The MIRRORS system has been primarily designed for objects without free-form surfaces and whose shape can be recovered from a relatively nondense set of points.

An approach for facilitating service management in networked virtual manufacturing environments

Abstract This paper defines an approach for management of networked entities, including either hardware devices or software services. In describing this approach, the paper presents a model architecture that is intended for, but not limited to, virtual environments. A sample application for dynamically monitoring and controlling remote facilities illustrates the benefits of this approach to virtual manufacturing. The service interface has functionality that enables a client to download its graphical representation and behaviors for display within a client applications virtual environment.

A model for line capacity design for PWB assembly systems

Abstract In a multi-product, flexible manufacturing environment, line capacity of printed wiring board (PWB) assembly systems may need to be designed at the beginning of each aggregate planning period because of demand fluctuation over multiple periods. A model of line capacity design problem and production planning at the aggregate level is developed, in which production and subcontracting are assumed to be two options for a firm to meet market demand. The model presented is a large-scale integer programming problem, it cannot be solved by using standard- or mixed-integer programming codes. Under the assumption that each machine line is dedicated to produce one product family, the model can be decomposed as a relatively small subproblem, and each subproblem has good properties by which the subproblems can be further simplified and decomposed over multiple planning periods. As the result, the original large-scale two-stage integer programming problem can be approximately solved by solving a series of small-scale mixed-integer programming, which can be implemented on a workstation or a PC. Computational studies show that the solution method is developed which gives near-optimal solutions with much less computational effort.

A framework for rapid computational prototyping of manufacturing entities

A framework for enhancement of conceptual tools for rapid computational prototyping of manufacturing entities is presented. A typical manufacturing entity (i.e. manufacturing system and/or individual part) is hierarchically represented in a computer and coupled with applications by dividing its information content into three computational elements: data, drawing and user interface. The information content is divided in this way because each of the above elements has a sufficiently distinct requirement for an efficient computer implementation. Although independent advances have taken place in computer data representation by highly efficient and focused data structures, in drawing representation by sophisticated computer graphics, as well as in user interface by a variety of interface media, these advances cannot be directly utilized in the design of a manufacturing entity unless they are efficiently integrated by relatively small programming effort as is deseribed in this rapid prototyping framework. The framework is implemented in object-oriented programming. A breadth of application areas for the framework is illustrated, and specific details are illustrated with reference to depth in one application area.

JIT approach to integrating production order scheduling and production activity control

Abstract Two of the most desirable features in integrating production order scheduling and production activity control is sustaining a finite workcentre capacity assumption for accurate production order scheduling, and efficiently performing a what-if sensitivity analysis to handle the dynamic uncertainties in production activity control. A finite workcentre capacity assumption leads to too many constraints that tends to slow down the computation process, and a what-if analysis tends to put too much strain on the design of the database system for production activity control. With a finite workcentre capacity and what-if sensitivity analysis capability as the basis, a holistic approach towards production planning and control is emphasized in this paper by simplifying the system based on JIT principles such as shallow levels in bill of material, a pull type backward planning and a clear identification of the type of operational environment for which the designed system is readily applicable, and data integrity by tight integration of the various modules in production planning and control. As an illustration, a system is designed and has been successfully applied to a rapidly changing made-to-order printed circuit board manufacturing environment.

Smart collision information processing sensors for fast moving objects

In this technical note we survey the area of smart collision information processing sensors. We review the existing technologies to detect collision or overlap between fast moving physical objects or objects in virtual environments, physical environments or a combination of physical and virtual objects. We report developments in the collision detection of fast moving objects at discrete time steps such as two consecutive time frames, as well as continuous time intervals such as in an interframe collision detection system. Our discussion of computational techniques in this paper is limited to convex objects. Techniques exist however to efficiently decompose non-convex objects into convex objects. We also discuss the tracking technologies for objects from the standpoint of collision detection or avoidance.