Bram de Smit

Tool profile and tool path calculation for free-form thick-layered fabrication

Abstract In several application fields, large sized, free-form objects of various soft materials are widely used. Available layered prototyping technologies cannot be applied for fabrication of these kinds of objects due to size limitations. The authors have developed a novel approach of layered manufacturing that is the most appropriate for physical concept modeling. This paper presents the algorithms for geometrically-based modeling of the profile curve of the flexible blade tool. It also describes the algorithm for direct slicing of the CAD model. The second part of the paper deals with the algorithms for slicing, tool positioning and tool path calculation. On the front surfaces of the layers G2, quasi G1 continuity can be implemented at the transition from one layer to another. In the circumferential direction G0 continuity exists.

Free-form thick layer object manufacturing technology for large-sized physical models

Abstract Large-sized free-form objects of different materials are widely used in various industrial applications. Currently, layered rapid prototyping technologies are not suitable for the fabrication of this kind of objects, due to the necessity of a large number of layers and the limitations in size. This paper reports a novel approach of layered manufacturing that is more appropriate for the fabrication of these large objects. A method of thick-layered object manufacturing is presented, which is based on a higher order approximation of the shape and application of a flexible curved cutting tool. The method allows the production of physical prototypes, which need little or no finishing. In order to meet the designers intend, as closely as possible, some feasible system characteristics are introduced. The process is ordered in a sequential way and provides a highly automated process. A hierarchical decomposition of the CAD geometry takes place into components, segments, layers and sectors, based on morphological analysis. This method enables the manufacturing and the re-assembly of the parts to produce the physical prototypes without affecting the requested functionality. Due to the possibility of obtaining multiple solutions in the physical model, much attention must be paid to the efficiency of the process.

SURVEY AND INVESTIGATION OF HAND MOTION PROCESSING TECHNOLOGIES FOR COMPLIANCE WITH SHAPE CONCEPTUALIZATION

An evergreen topic of human-computer interaction research is multi -modality. It has been considered important for the user interface of future computer aided conceptual design systems and what is hoped is that integration of, for instance, voice control, hand gesture/motion processing, and physical object scanning can increase both the semantic level and the efficiency of the interaction. In the area of computer mediated shape conceptualization, especially human hand motion detection and processing can play an important role. The authors’ research focuses on the study of the opportunities offered by hand motion processing in shape conceptualization. As a first step they have studied the state of the art and analyzed the technologies applicable to hand motion processing. This paper reports on the findings. The various technologies have been sorted in four categories: direct incomplete, direct complete, indirect incomplete and indirect complete detection. First, the principles supporting this categorization are explained in Section 2. The next four sections of the paper investigate the hand motion detection and processing technologies. Section 7 discusses the characteristics and operational parameters from the aspect of using hand motion for shape input in conceptual design. Our conclusion is that the currently known technologies

Self-Sensing of Deflection, Force, and Temperature for Joule-Heated Twisted and Coiled Polymer Muscles via Electrical Impedance

The recently introduced twisted and coiled polymer muscle is an inexpensive and lightweight compliant actuator. Incorporation of the muscle in applications that rely on feedback creates the need for deflection and force sensing. In this paper, we explore a sensing principle that does not require any bulky or expensive additional hardware: self-sensing via electrical impedance. To this end, we characterize the relation between electrical impedance on the one hand, and deflection, force, and temperature on the other hand for the Joule-heated version of this muscle. Investigation of the theoretical relations provides potential fit functions that are verified experimentally. Using these fit functions results in an average estimation error of 0.8%, 7.6%, and 0.5%, respectively, for estimating deflection, force, and temperature. This indicates the suitability of this self-sensing principle in the Joule-heated twisted and coiled polymer muscle.

Demands and Opportunities for Haptic and Tactile Feedback Technologies in an Airborne 3D Visualization Environment

The goal of this paper is to explore the field of haptic feedback technologies from the aspect of airborne visualization applications. While conventional Virtual Reality (VR) applications in most cases make extensive use of body mounted equipment this is expected to be unfavorable for airborne visualization environments. There new constraints and demands will govern. We give an overview of currently known VR technologies and explore possible directions in which new solutions for airborne visualization environments should be searched.Copyright

From Virtual Reality to Tangible Virtuality: An Inventory of the Technological Challenges

The paradigm of tangible virtuality (TV) has grown out from the paradigm of virtual reality (VR), leaving some key concepts of projective and immersive VR behind, but introducing many new ones. The ultimate objective of TV is to intuitively generate air-borne synthetic objects (SOs), share them between remote work environments in real time, simulate their physical behavior, and enable a physics-obeying interaction of humans with SOs. The major challenges for the implementation of TV originate in the need for multi-sensory integral rendering of SOs and un-instrumented generation of high fidelity sensations. These scientific and technological challenges have a strong influence on the current advancement of TV. Actually, implementation of fully featured TV environments is still in its infancy. The goal of this paper is to analyze the main implementation concepts and to make an inventory of the technological challenges and opportunities. Six major issues have been identified: (i) use of natural interaction modalities to express SOs, (ii) multi-aspect (e.g., tactile, haptic and auditory) volumetric rendering and sensation of air-borne SOs, (iii) simulation of physical behavior of interacting SOs, and (iv) manipulative human interaction with SOs. The paper investigates the opportunities of a short-term implementation based on the current technologies and of a near-future implementation based on emerging and anticipated technologies. The conclusion is that current technologies allow only a limited implementation of SOs and a low fidelity multi-sensorial experience. For a full scale implementation, radically new technologies and implementation concepts are needed, but it also requires a goal-driven extension of the existing scientific knowledge.Copyright

Exploring Haptic Feedback Principles for Application in Airborne Virtual Reality Environments

The goal of this paper is to explore the field of haptic feedback technologies, and give an overview on which principles are currently available for communicating different properties of virtual artifacts in a haptic/tactile manner to users. Secondly we evaluate this information from the aspect of a new virtual interaction environment that is being implemented in our research group, which aims at airborne representation of virtual objects without the need of body connected equipment, like for example goggles or exoskeletons. Based on this evaluation we try to discriminate which principles could be applied in order to create a realistic haptic feedback in this virtual interaction environment.Copyright

Smart Reading Aid for Detecting Problems With Reading Fluency and Comprehension

Brain signal and eye tracking technology have been intensively applied in cognitive science in order to study reading, listening and learning processes. Though promising results have been found in laboratory experiments, there are no smart reading aids that are capable to estimate difficulty during normal reading. This paper presents a new concept that aims to tackle this challenge. Based on a literature study and an experiment, we have identified several indicators for characterizing word processing difficulty by interpreting electroencelography (EEG) and electrooculography (EOG) signals. We have defined a computational model based on fuzzy set theory, which estimates the probability of word processing and comprehension difficulty during normal reading. The paper also presents a concept and functional prototype of a smart reading aid, which is used to demonstrate the feasibility of our solution. The results of our research proves that it is possible to implement a smart reading aid that is capable to detect reading difficulty in real time. We show that the most reliable indicators are related to eye movement (i.e. fixation and regression), while brain signals are less dependable sources for indicating word processing difficulty during continuous reading.

Tool- and Process Control Issues relating to the use of a Flexible Cutting Tool

The ICA research group is currently working on a novel Rapid Prototyping technology called Thick Layered Object Manufacturing (TLOM). The aim is to develop a technique capable of producing large concept models, built up from thick layers with freeform front faces. This technique produces layers that fit together with at least C1 continuity in the direction of layer building. A flexible cutting tool was conceptualised that is able to produce thick layers with smooth free-form faces. Important issues are controlling the shape of the flexible blade, calculation of the tool positions and tool path, and finding the process parameters for various materials and shapes to be used.