Zoltán Rusák

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.

Collaborative Shape Conceptualization in Virtual Design Environments

Vague discrete modeling is a flexible and adaptable means for designers to express and shape ideas in a collaborative environment.

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

Influence of complementing a robotic upper limb rehabilitation system with video games on the engagement of the participants: a study focusing on muscle activities.

Efficacious stroke rehabilitation depends not only on patients’ medical treatment but also on their motivation and engagement during rehabilitation exercises. Although traditional rehabilitation exercises are often mundane, technology-assisted upper-limb robotic training can provide engaging and task-oriented training in a natural environment. The factors that influence engagement, however, are not fully understood. This paper therefore studies the relationship between engagement and muscle activities as well as the influencing factors of engagement. To this end, an experiment was conducted using a robotic upper limb rehabilitation system with healthy individuals in three training exercises: (a) a traditional exercise, which is typically used for training the grasping function, (b) a tracking exercise, currently used in robot-assisted stroke patient rehabilitation for fine motor movement, and (c) a video game exercise, which is a proliferating approach of robot-assisted rehabilitation enabling high-level active engagement of stroke patients. These exercises differ not only in the characteristics of the motion that they use but also in their method of triggering engagement. To measure the level of engagement, we used facial expressions, motion analysis of the arm movements, and electromyography. The results show that (a) the video game exercise could engage the participants for a longer period than the other two exercises, (b) the engagement level decreased when the participants became too familiar with the exercises, and (c) analysis of normalized root mean square in electromyographic data indicated that muscle activities were more intense when the participants are engaged. This study shows that several sub-factors on engagement, such as versatility of feedback, cognitive tasks, and competitiveness, may influence engagement more than the others. To maintain a high level of engagement, the rehabilitation system needs to be adaptive, providing different exercises to engage the participants.

An Information Technological Specification of Abstract Prototyping for Artifact and Service Combinations

Various early prototyping techniques have been proposed for specific purposes and products, for instance for user-centered design of software tools, or interface design of consumer durables. Our research focuses on the development of a comprehensive approach, called abstract prototyping, to support a rich and complete prototyping of artifact-service combinations (ASCs). In this paper we present the concept and implementation of abstract prototypes (APs) from an information system point of view, and discuss both the general information structure and the specific information constructs used in our approach. First, the main constituents of APs are identified. Then, formal definitions of the involved information constructs are introduced. Afterwards, the practical implementation of the information constructs is discussed. As an information processing activity, abstract prototyping decomposes to four stages: (i) aggregation of information about the innovated ASCs, (ii) compilation and testing of the technical contents for abstract prototype(s), (iii) demonstration of the abstract prototype(s) to stakeholders, and (iv) refinement of the contents towards a final abstract prototype. It is assumed that ideation and elaboration of the concepts of the new artifact-service combinations precedes and produces input for abstract prototyping. It is proposed that APs should demonstrate real life manifestation of all characteristic operation and interaction/use processes, including the operation of the conceptualized artifact-service combination, the actions of the human actors, and the happenings in the surrounding environment. This can be achieved through the inclusion and proper instantiation of the necessary information constructs in the APs. The real life processes established by the existence and operations of ASCs is modeled and represented by scenarios. The contents of the abstract prototype are designed and demonstrated taking the interests and needs of the stakeholders into consideration. Eventually, an abstract prototype consists of two main constituents, namely narration and enactment, which enable the presentation of the technical contents. The former conveys a story about the manifestation of the ASCs and highlights the accompanying processes, and the latter visualizes the components, actors, arrangements, procedures, and happenings involved in them. The presented approach of information content development has been tested in master graduation projects, certain cycles of PhD research, and a company orientated process innovation project. The follow up research focuses on the development of a dedicated tool for abstract prototyping, and on the validation of proposed development and application methodology in complex industrial cases.Copyright

Collaborative Virtual Design Environments: A Treatise of the Supporting Technologies

The fourth generation of CAD/E systems appears in the form of collaborative virtual design environments (CVDEs). These distributed design support systems are based on a still developing new paradigm. Consequently, the standard architecture, functionality, and implementation of CVDEs are not fully elaborated yet. It is believed that six fundamental components are needed for a fully featured implementation: i. enhanced CAD/E kernel functionality, ii. multi-site imagining and advanced interaction, iii. high-speed communication and multi-channel networking, iv. collaboration support and virtual presence, v. knowledge asset management, and vi. interface to virtual enterprises. This paper investigates the supporting technologies with the aim to explore what is available, satisfactory, compatible, and experienced. The authors found that remarkable results have been achieved in terms of the supporting technologies, but for some CVDEs functions the technologies are not available so far. Currently the largest problem is to integrate the highly heterogeneous technologies into one coherent system. This is due partly to the inherent complexity of the problem, and partly to the uneven maturity of the technologies. It can be predicted without any hazard that dramatic changes will be witnessed soon in this front of research and development.Copyright

Attentive user interface for interaction within virtual reality environments based on gaze analysis

Eye movements can carry a rich set of information about someones intentions. In the case of physically impaired people gaze can be the only communication channel they can use. People with severe disabilities are usually assisted by helpers during everyday life activity, which in time can lead to a development of an effective visual communication protocol between helper and disabled. This protocol allows them to communicate at some extent only by glancing one towards the other. Starting from this premise, we propose a new model of attentive user interface featured with some of the visual comprehension abilities of a human helper. The purpose of this user interface is to be able to identify users intentions, and so to assist him/her in the process of achieving simple interaction goals (i.e. object selection, task selection). Implementation of this attentive interface is accomplished by way of statistical analysis of users gaze data, based on a hidden Markov model.

Towards Ubiquitous Design Support

Efficient computer support of product innovation processes has become an important issue of industrial competitiveness in the last forty years. As a consequence, there has been a growing demand for new computer-based tools and system. Various hardware, software and knowledge technologies have been used over the years as the basis of design support systems. With the appearance of network technologies, the conventional standalone workstation paradigm has been replaced by the paradigm of web-interconnected collaborative environments. Currently, the emerging and rapidly proliferating mobile and ubiquitous computing technologies create a technological push again. These technologies force us to reconsider not only the digital information processing devices and their interconnection, but also the way of obtaining, processing and communicating product design information. Many researches and laboratories are engaged with the development of novel concepts, architectures, tools and methods for next-generation design support environments. They will integrate many resources of the current collaborative design environments with pervasive computing functionality and large-scale mobility in a volatile manner. Part of the design support tools will have fixed location, but will be remotely accessible through wireless networks. Other part of the tools will be moving with the designers as portable, embedded, wearable and transferable devices, and will feature ad hoc connectivity. These not only offer new ways for aggregation, processing and presentation of design information, but also enable alternative ways of completing design activities. Our current research concentrates on three interrelated main issues: (i) studying workflow scenarios for future design support environment, (ii) investigation and integration of multiple technologies into an ad hoc interconnected heterogeneous infrastructure, and (iii) exploring efficient methods for utilizing new affordances in supporting product innovation. In this paper we report on the results of our recent technology study that analyzed the current results and trends of ubiquitous technology development, and tried to form a vision about the possible manifestation of future ubiquitous design support environments. Essentially, they have been conceptualized as ad hoc and volatile networks of fixed and mobile information collection, processing and communication units. This network functions as a complex service provider system, with special attention to the on-demand information management in the fuzzy front end of design projects.Copyright

A New Approach to Interactive Grasping Simulation of Product Concepts in a Virtual Reality Environment

Customer evaluation of concepts plays an important role in the design of handheld devices, such as bottles of douche gels and shampoos, where the phenomenon of grasping needs to be evaluated. In these applications important information on the aspects of ergonomics and user behaviors could be gathered from computer simulation. It is our ultimate goal to develop an environment in which users and designers can freely interact with product concepts. In our approach to grasping simulation there is no tactile feedback and we do not measure the exerted grasping forces. There is no wiring of the human hand, and the users are not limited in their movements. We measure the motion of the human hand, compute the grasping forces based on anthropometric data, and simulate the reaction of product concepts in a physically based virtual reality environment. Our contribution consists of: (i) a method, which takes into account the anatomy of the human hand in order to determine the maximum grasping forces, and (ii) an approach which enables to control the grasping forces based on (a) the penetration of the virtual human hand into the virtual model of product concept (b) the posture of the grasping, and (c) the angles of the joints. The paper reports on the framework of our approach and presents an application.Copyright