15 research outputs found
Architecture, design and source code comparison of ns-2 and ns-3 network simulators
Ns-2 and its successor ns-3 are discrete-event simulators. Ns-
3 is still under development, but offers some interesting characteristics
for developers while ns-2 still has a big user base.
This paper remarks current differences between both tools
from developers point of view. Leaving performance and resources
consumption aside, technical issues described in the
present paper might help to choose one or another alternative
depending of simulation and project management requirements.Ministerio de Educación y Ciencia TIN2006-15617-C03-03Junta de Andalucía P06-TIC-229
Performance evaluation over HW/SW co-design SoC memory transfers for a CNN accelerator
Many FPGAs vendors have recently included embedded
processors in their devices, like Xilinx with ARM-Cortex
A cores, together with programmable logic cells. These devices
are known as Programmable System on Chip (PSoC). Their ARM
cores (embedded in the processing system or PS) communicates
with the programmable logic cells (PL) using ARM-standard AXI
buses. In this paper we analyses the performance of exhaustive
data transfers between PS and PL for a Xilinx Zynq FPGA
in a co-design real scenario for Convolutional Neural Networks
(CNN) accelerator, which processes, in dedicated hardware, a
stream of visual information from a neuromorphic visual sensor
for classification. In the PS side, a Linux operating system is
running, which recollects visual events from the neuromorphic
sensor into a normalized frame, and then it transfers these
frames to the accelerator of multi-layered CNNs, and read results,
using an AXI-DMA bus in a per-layer way. As these kind of
accelerators try to process information as quick as possible, data
bandwidth becomes critical and maintaining a good balanced
data throughput rate requires some considerations. We present
and evaluate several data partitioning techniques to improve the
balance between RX and TX transfer and two different ways
of transfers management: through a polling routine at the userlevel
of the OS, and through a dedicated interrupt-based kernellevel
driver. We demonstrate that for longer enough packets,
the kernel-level driver solution gets better timing in computing a
CNN classification example. Main advantage of using kernel-level
driver is to have safer solutions and to have tasks scheduling in
the OS to manage other important processes for our application,
like frames collection from sensors and their normalization.Ministerio de Economía y Competitividad TEC2016-77785-
Analysis of source code metrics from ns-2 and ns-3 network simulators
Ns-2 and its successor ns-3 are discrete-event simulators which are closely related to each
other as they share common background, concepts and similar aims. Ns-3 is still under
development, but it offers some interesting characteristics for developers while ns-2 still
has a large user base. While other studies have compared different network simulators,
focusing on performance measurements, in this paper we adopted a different approach
by focusing on technical characteristics and using software metrics to obtain useful conclusions.
We chose ns-2 and ns-3 for our case study because of the popularity of the former in
research and the increasing use of the latter. This reflects the current situation where ns-3
has emerged as a viable alternative to ns-2 due to its features and design. The paper
assesses the current state of both projects and their respective evolution supported by
the measurements obtained from a broad set of software metrics. By considering other
qualitative characteristics we obtained a summary of technical features of both simulators
including, architectural design, software dependencies or documentation policies.Ministerio de Ciencia e Innovación TEC2009-10639-C04-0
Using virtual potential fields for electric wheelchair guidance
TetraNauta is an electric wheelchair guidance system intended for people with heavy motion impairments (such as persons with tetraplegia). It is specially useful when impairments also affect wheelchair steering as it is able to automatically guide wheelchairs between different points in a known environment (a hospital, a school, etc), conditioned with track marks painted on the floor. It also provides a semiautomatic navigation mode, where control is shared between user and navigation system. It is intended for learning wheelchair manipulation and as an aid in places where navigation is difficult or dangerous (i.e. for crossing narrow corridors)
Application of Robot Programming to the Teaching of Object-Oriented Computer Languages
Object-oriented programming (OOP) abstract concepts are often difficult to understand for students, since it is not easy to
find the equivalence of such concepts in daily life. In this paper we will study if an interdisciplinary approach based on an
introduction to robotics and robot programming helps the student in acquiring theOOPconcepts. For our experiments, we
selected a sample of thirty individuals among students with an adequate knowledge of procedural programming. This
sample was divided into two groups of fifteen students each: for the first one we used a standard introductory approach to
C#, whereas for the second one we developed an experimental course that included a demonstration program that
illustrated OOP basic concepts using the features of a specific type of commercial ball-shaped robot with sensing, wireless
communication and output capabilities. After the courses, both groups were evaluated by completing a multiple-choice
exam and aC#programming exercise. Our results show that the student group that attended the course including the robot
demo showed a higher interest level (i.e. they felt more motivated) than those students that attended the standard
introductory C# course. Furthermore, the students from the experimental group also achieved an overall better mark
TetraNauta: a intelligent wheelchair for users with very severe mobility restrictions
The TetraNauta project is a low cost, fully open steering system to allow people with heavy motor impairments to move in a known environments (hospitals, schools, home, etc.). It minimizes the steering effort, especially in long paths, while caring for user safety. Every TetraNauta wheelchair has a general map of the environment wherein it navigates in automatic mode. It also knows its actual position in the map using on-board sensors that detect absolute positioning marks. The system consists of a traffic management subsystem and wheelchair motion control subsystem. Virtual potential fields as a tool for implementing automatic guidance in the intelligent electric wheelchair are considere
Error adaptive tracking for mobile robots
In mobile robots it is usual that the desired trajectory is memorized or previously generated. When following a trajectory, there are several possibilities attending to the way in which the actual robot state can be related with the whole trajectory. One of them is the extension of the servosystem approach, usually called "trajectory tracking". This is the only possibility if we need strict temporal deterministic requirements. But if not, other possibilities appear. One of them is called "path following", where the path's point to track is the "nearest" (under several conditions) to the actual robot's position. In this paper we present another method suitable for nondeterministic systems, which we may call "error adaptive tracking", because the tracking pace adapts to the errors. Its benefits and advantages are identified. Afterwards, we determine how to construct this method and we apply it to the case of SIRIUS, an advanced wheelchair. Then a control law that ensures asymptotic stability is extracted using the second Lyapunov method and under the error adaptive tracking approach. Finally, we show the benefits of the new method, comparing it with the trajectory tracking approach.Ministerio de Ciencia y Tecnología TIC-2000-0087-P4-
Opening the Black Box: Explaining the Process of Basing a Health Recommender System on the I-Change Behavioral Change Model
Recommender systems are gaining traction in healthcare because they can tailor recommendations
based on users' feedback concerning their appreciation of previous health-related messages. However,
recommender systems are often not grounded in behavioral change theories, which may further increase
the effectiveness of their recommendations. This paper's objective is to describe principles for designing
and developing a health recommender system grounded in the I-Change behavioral change model that
shall be implemented through a mobile app for a smoking cessation support clinical trial. We built upon
an existing smoking cessation health recommender system that delivered motivational messages through a
mobile app. A group of experts assessed how the system may be improved to address the behavioral change
determinants of the I-Change behavioral change model. The resulting system features a hybrid recommender
algorithm for computer tailoring smoking cessation messages. A total of 331 different motivational messages
were designed using 10 health communication methods. The algorithm was designed to match 58 message
characteristics to each user pro le by following the principles of the I-Change model and maintaining the
bene ts of the recommender system algorithms. The mobile app resulted in a streamlined version that aimed
to improve the user experience, and this system's design bridges the gap between health recommender
systems and the use of behavioral change theories. This article presents a novel approach integrating
recommender system technology, health behavior technology, and computer-tailored technology. Future
researchers will be able to build upon the principles applied in this case study.European Union's Horizon 2020 Research and Innovation Programme under Grant 68112
Implementing a Distance Estimator for a Wildlife Tracking System Based on 802.15.4
In this work, a novel distance estimation mechanism using received signal strength
indication (RSSI) signals with ZigBee modules is designed, implemented and tested in several
scenarios. This estimator was used for a research project focused on a wildlife behavioral classification
system deployed in Doñana’s National Park. As a supporting feature for that project, this work
was implemented for locating animal’s collars acting as wireless nodes in order to find those who
went outside of the coverage area of the network or that were accidentally detached from animals.
This work describes the system architecture and the implementation of a mobile assistant capable of
recovering devices located beyond the coverage of the network. The analytical model needed for
distance estimation and the signal filtering are described, as well as the difficulties that the researchers
must deal when building robust location estimators. This theoretical model was applied to three
different scenarios and tested with two validation experiments.Junta de Andalucía P12-TIC-130
SIRIUS: Improving the maneuverability of powered wheelchairs
The indoor maneuverability of powered wheelchairs may be difficult or bothersome in several circumstances. In this paper, we describe an experimental powered wheelchair named SIRIUS, developed at the University of Seville, which introduces some simple but effective navigation aids. Special emphasis is placed on the implementation of recorded trajectory playback and in the shared control modes, i.e., the chair's guiding where both the user and the computer collaborate. Furthermore, SIRIUS is an open platform to essay another kinds of functional or navigational aids, because its hardware architecture is based on a commercial PC. This would permit many devices that are frequently needed by the chair driver to be integrated smoothly into the chair controller.Ministerio de Ciencia y Tecnología TIC-2000-0087-P4-0