49 research outputs found

    Using Modelica for advanced Multi-Body modelling in 3D graphical robotic simulators

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    This paper describes a framework to extend the 3D robotic simulation environment Gazebo, and similar ones, with enhanced, tailor-made, multi-body dynamics specified in the Modelica language. The body-to-body interaction models are written in Modelica, but they use the sophisticated collision detection capabilities of the Gazebo engine. This contribution is a first step toward the simulation of complex robotics systems integrating detailed physics modelling and realistic sensors such as lidar and cameras. A proof-of-concept implementation is described in the paper integrating Gazebo collider and the Modelica MultiBody library, and the results obtained when simulating the interaction of an elastic sphere with a rigid plane are shown

    Function Spaces, Approximation Theory, and Their Applications

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    The purpose of this special issue was to present new developments in the theory of function spaces, along with the deep interconnections with approximation theory and the applications in various fields of pure and applied mathematics. The reaction of the mathematical community was very satisfactory. We collected thirty-five submissions, covering a wide range of mathematical topics, ten of which were found to be suitable for publications in this issue. The major part of the accepted papers treats function spaces and their applications. In this respect, in the article by X Yang et al. a new class of function spaces, named "multi-βnormed spaces", is introduced, in connection with stability properties of certain type of functional equations, while, in the paper by A. A. Bakery, sequential spaces of Orlicz type are studied and connected with the theory of summability. In the review paper by L. Angeloni and G. Vinti, the approximation theory in the space of functions with bounded variation is developed, in view of applications to signal processing. Different notions of variation are considered and several approximation theorems for families of integral or discrete type operators are given. In the more theoretical article by S. Wulede et al., a new class of Banach spaces which generalizes the class of uniformly extremely convex Banach spaces is introduced, and some characterizations of these spaces are given. Another paper by N. Khan treats the convergence of new type of double sequences, here introduced, in n-normed spaces. An interesting abstract approach to the theory of filter convergence is given in the article by A. Boccuto and X. Dimitriou, in which the links with function spaces and approximation theory are also dealt with. Other aspects of the theory of function spaces and their interconnections with calculus of variations, numerical analysis, complex variables, and stochastic processes are discussed, respectively, in the articles by T. Ma and Y. Feng, H. Wang et al., S. Wang and T. Zhan, and finally P. Duan.These four papers point out how certain methods of general approximation theory in function spaces can be employed in order to solve problems coming from a large variety of mathematical fields. We think that these contributions may represent starting points for new researches in the field of function spaces and approximation theory

    Task-Agnostic Object Recognition for Mobile Robots through Few-Shot Image Matching

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    To assist humans with their daily tasks, mobile robots are expected to navigate complex and dynamic environments, presenting unpredictable combinations of known and unknown objects. Most state-of-the-art object recognition methods are unsuitable for this scenario because they require that: (i) all target object classes are known beforehand, and (ii) a vast number of training examples is provided for each class. This evidence calls for novel methods to handle unknown object classes, for which fewer images are initially available (few-shot recognition). One way of tackling the problem is learning how to match novel objects to their most similar supporting example. Here, we compare different (shallow and deep) approaches to few-shot image matching on a novel data set, consisting of 2D views of common object types drawn from a combination of ShapeNet and Google. First, we assess if the similarity of objects learned from a combination of ShapeNet and Google can scale up to new object classes, i.e., categories unseen at training time. Furthermore, we show how normalising the learned embeddings can impact the generalisation abilities of the tested methods, in the context of two novel configurations: (i) where the weights of a Convolutional two-branch Network are imprinted and (ii) where the embeddings of a Convolutional Siamese Network are L2-normalised

    Exploring Task-agnostic, ShapeNet-based Object Recognition for Mobile Robots

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    This position paper presents an attempt to improve the scalability of existing object recognition methods, which largely rely on supervision and imply a huge availability of manually-labelled data points. Moreover, in the context of mobile robotics, data sets and experimental settings are often handcrafted based on the specific task the object recognition is aimed at, e.g. object grasping. In this work, we argue instead that publicly available open data such as ShapeNet can be used for object classification first, and then to link objects to their related concepts, leading to task-agnostic knowledge acquisition practices. To this aim, we evaluated five pipelines for object recognition, where target classes were all entities collected from ShapeNet and matching was based on: (i) shape-only features, (ii) RGB histogram comparison, (iii) a combination of shape and colour matching, (iv) image feature descriptors, and (v) inexact, normalised cross-correlation, resembling the Deep, Siamese-like NN architecture of Submariam et al. (2016). We discussed the relative impact of shape-derived and colour-derived features, as well as suitability of all tested solutions for future application to real-life use cases

    From Models to Software Through Automatic Transformations: An AADL to ROS End-to-End Toolchain

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    Modelling complex systems is a common practice and de facto standard across most application domains in engineering. Although it would seem unreasonable - and quite impractical - to build a structure as complex as a bridge without a reference blueprint detailing how to arrange all of its building blocks, in Software Development, and, particularly in the context of Robotics, examples adhering to rigorous modelling routines are still relatively rare to find. Yet, models help understanding complex problems while pinpointing their potential solutions, through abstraction. Further, models aid communication, i.e., the unambiguous exchange of reasoning processes across the involved agents. The complexity of Robotic Software Systems suggests that a widespread application of modelling techniques, from the very initial implementation stages, would (i) ease the definition, engineering and debugging of the related sub-features significantly, and (ii) guide collaborative efforts towards a common standard. To this aim, we presented a toolchain conceived for parsing an input AADL model into a compilable code suite. Keeping the model building and the linkage of the robot application with the ROS environment in the developer's hands, this framework delegates all the remaining tasks to an automated code generator, producing a fully-functioning ROS packages (i.e., already configured and ready for compiling) as output. We first presented the discussed framework, highlighted its related advantages - when compared to the only other similar approach found in the literature -, and used it as an exemplary use case, to prompt broader discussions on the benefits of model-based software development in Robotics

    Using AADL to model and develop ROS-based robotic application

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    Modern robotic systems are a combination of sophisticated software and hardware components and they offer complex functionalities. While popular middlewares that promote component-level reusability and assist development already exist, there are no established techniques or procedures that use a formal approach to robot system and architecture design yet. This work aims at the long term goal of model-based design and development of complex robot systems (and their software architectures), by surpassing current techniques based on personal expertise, and best practices, in favor of purely model-based approaches. Our contribution tackles the problem from the ground up by proposing a way to model ROS nodes, and robotic architectures in general, using the Architecture Analysis and Design Language (AADL). The result is connected to and based on ROS, but not bound to it. It provides a starting point for the future definition of a general formal framework to describe complex robotic architectures suitable for automatic code generation and system verification
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