This paper presents a novel systematic approach to identify the dynamic parameters of robotic manipulators. A sequential identification procedure is first proposed to deal with the difficulties usually encountered with standard approaches. An all-accelerometer inertial measurement unit (IMU) is also suggested to estimate the joint velocities and accelerations, which are traditionally obtained by differentiating the joint positions. The IMU kinematics and the computation method for estimation joint motion from IMUs are provided. The proposed method yields promising results in improving the identification precision compared to conventional methods. Finally, practical experiments are conducted to validate the theoretical results.

In this work we study edge weights for two specific families of increasing trees, which include binary increasing trees and plane-oriented recursive trees as special instances, where plane-oriented recursive trees serve as a combinatorial model of scale-free random trees given by the m = 1 case of the Barabási–Albert model. An edge e = (k, l), connecting the nodes labelled k and l, respectively, in an increasing tree, is associated with the weight we = |k − l|. We are interested in the distribution of the number of edges with a fixed edge weight j in a random generalized plane-oriented recursive tree or random d-ary increasing tree. We provide exact formulas for expectation and variance and prove a normal limit law for this quantity. A combinatorial approach is also presented and applied to a related parameter, the maximum edge weight.

We consider the minimum-weight path between any pair of nodes of the n-vertex complete graph in which the weights of the edges are i.i.d. exponentially distributed random variables. We show that the longest of these minimum-weight paths has about α* log n edges, where α* ≈ 3.5911 is the unique solution of the equation α log α − α = 1. This answers a question posed by Janson [8].

We prove that there exists a constant c such that, for any integer Δ, the Ramsey number of a bipartite graph on n vertices with maximum degree Δ is less than 2cΔn. A probabilistic argument due to Graham, Rödl and Ruciński implies that this result is essentially sharp, up to the constant c in the exponent. Our proof hinges upon a quantitative form of a hypergraph packing result of Rödl, Ruciński and Taraz.

We derive new results for the performance of a simple greedy algorithm for finding large independent sets and matchings in constant-degree regular graphs. We show that for r-regular graphs with n nodes and girth at least g, the algorithm finds an independent set of expected cardinalitywhere f(r) is a function which we explicitly compute. A similar result is established for matchings. Our results imply improved bounds for the size of the largest independent set in these graphs, and provide the first results of this type for matchings. As an implication we show that the greedy algorithm returns a nearly perfect matching when both the degree r and girth g are large. Furthermore, we show that the cardinality of independent sets and matchings produced by the greedy algorithm in arbitrary bounded-degree graphs is concentrated around the mean. Finally, we analyse the performance of the greedy algorithm for the case of random i.i.d. weighted independent sets and matchings, and obtain a remarkably simple expression for the limiting expected values produced by the algorithm. In fact, all the other results are obtained as straightforward corollaries from the results for the weighted case.

Define the Linus sequence Ln for n ≥ 1 as a 0–1 sequence with L1 = 0, and Ln chosen so as to minimize the length of the longest immediately repeated block Ln−2r+1 ⋅⋅⋅ Ln−r = Ln−r+1 ⋅⋅⋅ Ln. Define the Sally sequence Sn as the length r of the longest repeated block that was avoided by the choice of Ln. We prove several results about these sequences, such as exponential decay of the frequency of highly periodic subwords of the Linus sequence, zero entropy of any stationary process obtained as a limit of word frequencies in the Linus sequence and infinite average value of the Sally sequence. In addition we make a number of conjectures about both sequences.

Modern design embraces digital augmentation, especially in the interplay of digital media content and the physical dispersion and handling of information. Based on the observation that small paper memos with sticky backs (such as Post-Its™) are a powerful and frequently used design tool, we have created Post-Bits, a new interface device with a physical embodiment that can be handled as naturally as paper sticky notes by designers, yet add digital information affordances as well. A Post-Bit is a design prototype of a small electronic paper device for handling multimedia content, with interaction control and display in one thin flexible sheet. Tangible properties of paper such as flipping, flexing, scattering, and rubbing are mapped to controlling aspects of the multimedia content such as scrubbing, sorting, or up- or downloading dynamic media (images, video, text). In this paper we discuss both the design process involved in building a prototype of a tangible interface using new technologies, and how the use of Post-Bits as a tangible design tool can impact two common design tasks: design ideation or brainstorming, and storyboarding for interactive systems or devices.

Designers are interacting with an increasing number of digital tools in their design process; however, these are usually in addition to the traditional and ubiquitous paper-based design journals. This paper explores the medium of informal design information and its relationships with sketching behavior over three stages of the design process: preliminary investigation and user needs analyses, concept generation and development, and prototyping and testing. Our test bed consists of tangible, digital, and hybrid design journals collected from four semesters of UC Berkeley's graduate level, multidisciplinary course titled “Managing the New Product Development Process: Design Theory and Methods.” We developed protocols for two categories of analysis: one that codes for the media type of each journal and its content, and another one that characterizes the content within the journal. We found a trend toward hybrid digital–tangible journals for the engineering students over the 4-year period. These hybrid journals exhibited a higher degree of detail over advancing design stages, which has been shown to correlate with improved project performance. We also present several case studies of unusual design journals that illustrate the range of designers' interpretations of design journals as a medium. Based on this descriptive research, features for interactive hybrid tangible–digital design journals are recommended.

Industrial designers make sketches and physical models to start and develop ideas and concept designs. Such representations have advantages that they support fast, intuitive, rich, sensory exploration of solutions. Although existing tools and techniques provide adequate support where the shape of the product is concerned, the exploration of surface qualities such as material and printed graphics is supported to a much lesser extent. Moreover, there are no tools that have the fluency of sketching that allow combined exploration of shape, material, and their interactions. This paper evaluates Skin, an augmented reality tool designed to solve these two shortcomings. By projecting computer-generated images onto the shape model Skin allows for a “sketchy” tangible interaction where designers can explore surface qualities on a three-dimensional physical shape model. The tool was evaluated in three design situations in the domain of ceramics design. In each case, we found that the joint exploration of shape and surface provided creative benefits in the form of new solutions; in addition, a gain in efficiency was found in at least one case. The results show that joint exploration of shape and surface can be effectively supported with tangible augmented reality techniques and suggest that this can be put to practical use in industry today.

Tangible interaction is an emerging field of human–computer interaction that links the digital and the physical worlds by embedding computation in physical artifacts and environments. This paper shares our experience teaching tangible interaction over the past 4 years in an interdisciplinary, project-based laboratory course at Tufts University. Although the course is offered through the Computer Science Department, it reflects the multidisciplinary nature of the field, merging product engineering practices with a design studio approach. With a diverse mix of students, this approach has fostered creativity and hands-on learning. Throughout the course students have created innovative interfaces that not only capture fundamental concepts of tangible interaction but also contribute novel techniques for supporting collaborative design. We discuss examples of student-created interfaces and illustrate the relationship between the methods employed in the course and the artifacts created. We also share our recommendations for implementing such a course in institutions with constraints similar to ours including a limited budget and minimal laboratory space.

The use of tangible objects is paramount in industrial design. Throughout the design process physical prototypes are used to enable exploration, simulation, communication, and specification of designs. Although much is known about prototyping skills and technologies, the reasons why and how such models are employed in design practice are poorly understood. Advanced techniques and design media such as virtual and augmented prototyping are being introduced without insight as to their benefits. We believe that an augmented prototyping system, that is, employing augmented reality technology to combine physical and digital representations, could positively influence the design process. However, we lack knowledge on why and how it might facilitate design. This paper reports on case studies performed in different domains of industrial design. At each of three Dutch design offices, a project was followed with particular attention to physical prototyping and group activities. The projects encompassed information appliance design, automotive design, and interior design. Although the studies vary in many aspects (product domain, stakeholders, duration), the findings can be applied in conceptualizing advanced prototyping systems to support industrial design. Furthermore, the data reveal that the roles of a prototype in current practice are not necessarily utilitarian; for example, the prototype may serve as a conversation piece or as seducer. Based on so-called “hints,” bottlenecks and best practices concerning concept articulation are linked to usage scenarios for augmented tangible prototyping. The results point to modeling and communication scenarios. Detailed study of the cases indicates that communication activities, especially design reviews, would benefit most from interactive augmented prototyping.

We present an alternative video-making framework for children with tools that integrate video capture with movie production. We propose different forms of interaction with physical artifacts to capture storytelling. Play interactions as input to video editing systems assuage the interface complexities of film construction in commercial software. We aim to motivate young users in telling their stories, extracting meaning from their experiences by capturing supporting video to accompany their stories, and driving reflection on the outcomes of their movies. We report on our design process over the course of four research projects that span from a graphical user interface to a physical instantiation of video. We interface the digital and physical realms using tangible metaphors for digital data, providing a spontaneous and collaborative approach to video composition. We evaluate our systems during observations with 4- to 14-year-old users and analyze their different approaches to capturing, collecting, editing, and performing visual and sound clips.

Tangible interaction is a growing area of human–computer interaction research that has become popular in recent years. Yet designers and researchers are still trying to comprehend and clarify its nature, characteristics, and implications. One approach has been to create frameworks that help us look back at and categorize past tangible interaction systems, and look forward at the possibilities and opportunities for developing new systems. To date, a number of different frameworks have been proposed that each provide different perspectives on the tangible interaction design space, and which can guide designers of new systems in different ways. In this paper, we map the space of tangible interaction frameworks. We order existing frameworks by their general type, and by the facets of tangible interaction design they address. One of our main conclusions is that most frameworks focus predominantly on the conceptual design of tangible systems, whereas fewer frameworks abstract the knowledge gained from previous systems, and hardly any framework provides concrete steps or tools for building new tangible systems. In addition, the facets most represented in existing frameworks are those that address the interactions with or the physicality of the designed systems. Other facets, such as domain-specific technology and experience, are rare. This focus on design, interaction, and physicality is interesting, as the origins of the field are rooted in engineering methods and have only recently started to incorporate more design-inspired approaches. As such, we expected more frameworks to focus on technologies and to provide concrete building suggestions for new tangible interaction systems.

We present a heuristic framework for attacking the undecidable termination problem of logic programs, as an alternative to current termination/nontermination proof approaches. We introduce an idea of termination prediction, which predicts termination of a logic program in case that neither a termination nor a non-termination proof is applicable. We establish a necessary and sufficient characterization of infinite (generalized) SLDNF-derivations with arbitrary (concrete or moded) queries, and develop an algorithm that predicts termination of general logic programs with arbitrary nonfloundering queries. We have implemented a termination prediction tool and obtained quite satisfactory experimental results. Except for five programs which break the experiment time limit, our prediction is 100% correct for all 296 benchmark programs of the Termination Competition 2007, of which 18 programs cannot be proved by any of the existing state-of-the-art analyzers like AProVE07, NTI, Polytool, and TALP.