Flexible Object Manipulation

Flexible objects are a challenge to manipulate. Their motions are hard to predict, and the high number of degrees of freedom makes sensing, control, and planning difficult. Additionally, they have more complex friction and contact issues than rigid bodies, and they may stretch and compress. In this thesis, I explore two major types of flexible materials: cloth and string. For rigid bodies, one of the most basic problems in manipulation is the development of immobilizing grasps. The same problem exists for flexible objects. I have shown that a simple polygonal piece of cloth can be fully immobilized by grasping all convex vertices and no more than one third of the concave vertices. I also explored simple manipulation methods that make use of gravity to reduce the number of fingers necessary for grasping. I have built a system for folding a T-shirt using a 4 DOF arm and a fixed-length iron bar which simulates two fingers. The main goal with string manipulation has been to tie knots without the use of any sensing. I have developed single-piece fixtures capable of tying knots in fishing line, solder, and wire, along with a more complex track-based system for autonomously tying a knot in steel wire. I have also developed a series of different fixtures that use compressed air to tie knots in string. Additionally, I have designed four-piece fixtures, which demonstrate a way to fully enclose a knot during the insertion process, while guaranteeing that extraction will always succeed

A modular and interactive OLED-based lighting system

The concept of a flexible, large-area, organic light emitting diode (OLED)-based lighting system with a modular structure and built-in intelligent light management is introduced. Such a flexible, thin, portable lighting system with discreetly integrated electronics is important in order to allow the implementation of the lighting system into a variety of places, such as cars and temporary expedition areas. A modular construction of an OLED lighting panel makes it possible to control each OLED cell individually. This not only enables us to counteract aging or degradation effects in the OLED cells but it also allows individual OLED module brightness control to support human or ambient interaction based on integrated or centralized sensors. Moreover, integrating the driving electronics in the backplane of an OLED module improves the energy efficiency of operating large OLED panels. The thin, modular construction and individual, dynamic control are successfully demonstrated

Analiza pristupačnosti strana u svrhu projektiranja modularnih naprava

This paper describes the methodology for the identification of accessibility of faces of 3D model of the workpiece, for the purpose of its positioning and clamping, by use of developed software application. Software application is developed in SolidWorks environment with the purpose to design modular fixtures. Using the SolidWorks API, MS Excel, object-oriented programming language Visual Basic 6 and logic in the form of production rules and algorithms, the development of software application was executed. Identification of the accessibility of faces of 3D model of the workpiece is based on the identification of characteristic coefficients and generation of their values. The coefficient of accessibility of faces appears as a final result of conducted analysis of face`s accessibility of the 3D model workpiece. The results gained from this software application are used to generate points for the positioning and clamping in the process of modular fixtures design. Developed software application provides mathematical notation of the face`s accessibility for the adopted conditions and restrictions, which was verified on the particular workpiece.Ovaj rad opisuje postupak za identificiranje pristupačnosti strana 3D modela radnog komada, u svrhu njegovog pozicioniranja i stezanja, korištenjem razvijene programske aplikacije. Programska aplikacija je razvijena u SolidWorks okružju u svrhu projektiranja modularnih naprava. Korištenjem SolidWorks API, MS Excel, objektno orijentiranog programskog jezika Visual Basic 6 i logike u obliku produkcijskih pravila i algoritama, izvršen je razvoj programske aplikacije. Identifikacija pristupačnosti strana 3D modela radnog komada bazira se na identifikaciji karakterističnih koeficijenata i generiranja njihovih vrijednosti. Koeficijent pristupačnosti strane se pojavljuje kao krajnji rezultat provedene analize pristupačnosti strane 3D modela radnog komada. Rezultati iz ove programske aplikacije koriste se za generiranje točaka za pozicioniranje i stezanje u procesu projektiranja modularnih naprava. Razvijena programska aplikacija daje matematički zapis pristupačnosti strane za usvojene uvjete i ograničenja, što je verificirano na konkretnom radnom predmetu

Sensor Based Fixture Design and Verification

The objectives of Sensor Based Fixture Design and Verification (SFDV) research are to provide the means for detecting contact failure of the workpiece with fixture locators and for preventing incorrect loading of the workpiece in a fixture. The fixtures that involve complex free-form surfaces especially in the aerospace industries face problems caused by the contact failure of the workpiece with locators. In batch and mass production defects often occur due to incorrect loading of the workpiece in a fixture by an operator due to fatigue or inadvertence. The current fixturing research is focussed on improving the fixture quality and other aspects and do not address these issues. This research is focussed on three areas, to generate algorithms for automatically foolproofing the fixtures, to build locators with embedded sensors that could be used to verify the contact and foolproof the existing fixtures, and to design and experimentally validate fixtures for free-form surfaces with sensors to verify the location. In foolproofing, workpieces were classified into different categories to identify the existence of a solution and the geometry was simplified and used to search for a solution based on symmetry/asymmetry to discover a foolproofing location. The algorithms were implemented in a CAD software and the solutions were verified in 3D space. The locators with inbuilt sensors were designed for foolproofing and location verification purposes and the sensors were used in case studies to establish credibility. A sensor based fixture design method is created for the part location of free-form surfaces using fiber optic sensors. An experimental fixture with sensors incorporated in the locators was used to determine the effects of surface curvature on the sensitivity of the sensors. A new theory on best locations for the sensor based locators by utilizing surface curvature is proposed based on the experimental results. The SFDV implementation may help realize the dream for any manufacturing sys­tem aspiring to move beyond the six sigma levels of quality and achieve zero defects

A Genetic Algorithm for Fixture Synthesis and Variation

Concepts in manufacturing such as CIMS (Computer Integrated Manufacturing Systems), JIT (Just In Time), Lean Production, Virtual Manufacturing, and Flexible Fixturing have been proposed to meet the fundamental requirements of manufacturing - decrease the cost and satisfy the needs of customers. Fast fixture generation and fixture reusability are essential in the current manufacturing environment. The dissertation focuses on the models, methods, and algorithms for fixture synthesis and variation that satisfy the functional requirements specified by on-site industrial engineers. With the reusability of a fixture base combined with variation of other fixture components, fixture configuration can be rapidly adapted and accommodated to the new workpiece. The dissertation presents methods and algorithms for fixture base synthesis, which directly result in fixture reusability. Optimization functions are derived based on engineering requirements due to the mass production nature of automotive parts. Specific optimization algorithms are developed and their complexities, compared to other alternatives, are comprehensively evaluated according to different optimization functions. The fixture variation and reusability provide an engineering tool to rapidly generate and validate fixtures in production planning stage. It applies scientific reasoning methodology in combination with best knowledge of fixture designs, which heavily relies on designers\u27 manufacturing knowledge and experience. It also provides means to bridge the gap between CAD and CAM integration and therefore reduces the new product and production development cycle time and cost while maintaining the quality of fixtures

A Rapidly Reconfigurable Robotics Workcell and Its Applictions for Tissue Engineering

This article describes the development of a component-based technology robot system that can be rapidly configured to perform a specific manufacturing task. The system is conceived with standard and inter-operable components including actuator modules, rigid link connectors and tools that can be assembled into robots with arbitrary geometry and degrees of freedom. The reconfigurable "plug-and-play" robot kinematic and dynamic modeling algorithms are developed. These algorithms are the basis for the control and simulation of reconfigurable robots. The concept of robot configuration optimization is introduced for the effective use of the rapidly reconfigurable robots. Control and communications of the workcell components are facilitated by a workcell-wide TCP/IP network and device level CAN-bus networks. An object-oriented simulation and visualization software for the reconfigurable robot is developed based on Windows NT. Prototypes of the robot systems configured to perform 3D contour following task and the positioning task are constructed and demonstrated. Applications of such systems for biomedical tissue scaffold fabrication are considered.Singapore-MIT Alliance (SMA

Fixture-Based Design Similarity Measures for Variant Fixture Planning

One of the important activities in process planning is the design of fixtures to position, locate and secure the workpiece during operations such as machining, assembly and inspection. The proposed approach for variant fixture planning is an essential part of a hybrid process planning methodology.The aim is to retrieve, for a new product design, a useful fixture from a given set of existing designs and their fixtures. Thus, the variant approach exploits this existing knowledge. However, since calculating each fixture's feasibility and then determining the necessary modifications for infeasible fixtures would require too much effort, the approach searches quickly for the most promising fixtures based on a surrogate design similarity measure. Then, it evaluates the definitive usefulness metric for those promising fixtures and identifies the best one for the new design

The effects of an interactive computerized multimedia tutorial on knowledge gain in modular fixturing design concepts

This study was designed to compare student knowledge gain from learning modular fixturing design concepts by computer tutorial versus traditional lecture. The use of computer tutorial to support engineering and technology classroom instructions has been a major issue for many studies. The undergraduate curricula in engineering and technology are becoming increasingly complex due to the today\u27s modern wide variety of manufacturing processes. The concept of modular fixturing in tool design course is one of the technical competencies which most industries would like graduates to be able to apply their knowledge to real-world problems and situations. An interactive computerized multimedia tutorial named ToolTRAIN was developed and administered to undergraduate students in the Industrial Technology program at the University of Northern Iowa. By integrating information in a graphical manner such as 3D visualization through animation, ToolTRAIN demonstrated how several modular fixturing components can be assembled with a wide variety of workpieces. A quasi-experimental design employing pre- and post-instruction tests was utilized for the study. Two preexisting groups of students were assigned to either the experimental or control group. Both groups were instructed on the same general topics covered in this study. A pretest was given to both groups. Three hours were used to teach the control group the concepts and theories of modular fixturing design concepts by lecture. On the other hand, the experimental group was expected to utilize ToolTRAIN for three hours. The posttest was administered to all subjects to measure knowledge gain of modular fixturing design concepts after the instruction. The data were analyzed using t tests to compare group mean of change scores. All hypotheses were tested at the .05 level of significance. This research indicated that there were significant differences between the computer tutorial program and lecture method. The experimental (computer tutorial) group achieved significantly higher improvement in scores than the control (lecture) group. Also, the learning time actually spent using ToolTRAIN was less that for the control group. Based on this research it was concluded that the ToolTRAIN interactive multimedia tutorial program can be used as an effective teaching method for modular fixturing design concepts. Future research should expand the sample size used in the investigation with tighter control of control group module content. ToolTRAIN can also be used for more complex concepts of modular fixturing system and applications

Robust Design of a Fixture Configuration in the Presence of form Deviations

During machining, the tool path is defined with respect to the workpiece reference frame. The workpiece's boundary surfaces have form deviations, and the geometry and the position of the locators are imperfect. The resulting misalignment produces geometrical errors in the features machined on the workpiece. The main purpose of this work is to investigate how the geometric errors of a machined surface are related to the main sources of the locator errors and to the form deviations of the workpiece. A mathematical framework is presented for an analysis of the relationship among the manufacturing errors, the part form deviations, and the locator errors