Filipe Amaral

Enhanced dielectric response of GeO2-doped CaCu3Ti4O12 ceramics

CaCu3Ti4O12 ceramic samples were prepared by solid state conventional route using stoichiometric amounts of CuO, TiO2, and CaCO3. Afterward the material was doped with GeO2 with concentrations up to 6% by weight and sintered at 1050 °C for 12 h. The influence of doping on the microstructure, vibrational modes, and dielectric properties of the material was investigated by x-ray diffraction, scanning electron microscopy coupled with an energy dispersive spectrometer, and infrared and dielectric measurements between 100 Hz and 30 MHz. The materials presented huge dielectric response, which increases with doping level relative to undoped CaCu3Ti4O12. The main effect of doping on the microstructure is the segregation of Cu-rich phase in the ceramic grain boundaries. Cole–Cole modeling correlates well the effects of this segregation with the relaxation parameters obtained. The intrinsic phonon contributions for the dielectric response were obtained and discussed together with the structural evolution of the system.

Rich and robust human-robot interaction on gesture recognition for assembly tasks

The adoption of robotics technology has the potential to advance quality, efficiency and safety for manufacturing enterprises, in particular small and medium-sized enterprises. This paper presents a human-robot interaction (HRI) system that enables a robot to receive commands, provide information to a human teammate and ask them a favor. In order to build a robust HRI system based on gesture recognition, three key issues are addressed: richness, multiple feature fusion and failure verification. The developed system has been tested and validated in a realistic lab with a real mobile manipulator and a human teammate to solve a puzzle game.

Skill-based anytime agent architecture for logistics and manipulation tasks: EuRoC Challenge 2, Stage II - Realistic Labs: Benchmarking

Nowadays, the increase of robotic technology application to industry scenarios is notorious. Proposals for new effective solutions are in continuous development once industry needs a constantly improvement in time as well as in production quality and efficiency. The EuRoC research project proposes a scientific competition in which research and industry manufacturers joint teams are encouraged to develop and test solutions that can solve several issues as well as be useful in manufacturing improvement. This paper presents the TIMAIRIS architecture and approach used in the Challenge 2 - Stage II - Benchmarking phase, namely regarding the perception, manipulation and planning strategy that was applied to achieve the tasks objectives. The used approach proved to be quite robust and efficient, which allowed us to rank first in the Benchmarking phase.

Improving and Benchmarking Motion Planning for a Mobile Manipulator Operating in Unstructured Environments.

This paper presents the use, adaptation and benchmarking of motion planning tools that will be integrated with the KUKA KMR iiwa mobile robot. The motion planning tools are integrated in the robotic agent presented in [1]. The adaptation consists on algorithms developed to increase the robustness and the efficiency to solve the motion planning problems. These algorithms combine existing motion planners with a trajectory filter developed in this work. Finally, the benchmarking of different motion planners is presented. Three motion planning tasks with a growing level of complexity are taken in consideration for the tests in a simulation environment. The motion planners that provided the best results were RRTConnect for the two less complex tasks and PRM* for the most difficult task.

Real-time multi-object tracking on highly dynamic environments

An accurate representation of the environment is important to plan tasks and efficiently control an autonomous robot. Multi-object tracking has long been an important task in robotics research whenever an autonomous robot needs to plan its tasks on an environment with multiple moving objects. Specially when the application is defined by real-time constraints in a fast-paced environment, a trade-off between accuracy and performance is automatically imposed. This paper presents a solution for real-time multi-object tracking on stochastic and highly dynamic environments. Although not limited to this specific application domain, the implementation and evaluation of this solution was performed on a team of autonomous soccer-playing robots. The proposed solution is detailed from the detection and feature extraction phase to the general problem of efficiently tracking objects in the environment. Results on the real testbed are also presented and discussed.

Human-Robot Collaboration and Safety Management for Logistics and Manipulation Tasks

To realize human-robot collaboration in manufacturing, industrial robots need to share an environment with humans and to work hand in hand. This introduces safety concerns but also provides the opportunity to take advantage of human-robot interactions to control the robot. The main objective of this work is to provide HRI without compromising safety issues in a realistic industrial context. In the paper, a region-based filtering and reasoning method for safety has been developed and integrated into a human-robot collaboration system. The proposed method has been successfully demonstrated keeping safety during the showcase evaluation of the European robotics challenges with a real mobile manipulator.

Microwaves dielectric properties of Y 3 Fe 5 O 12 -CaCu 3 Ti 4 O 12 composites

A study of the effect of the presence of Y3Fe5O12 (YIG) in the dielectric properties of the CaCu3Ti4O12 (CCTO) is presented. The samples were prepared by the solid state method. Mechanical alloying followed by the solid state procedure had been successfully used to produce powders of CCTO and YIG to be used in the composites. We also look at the effect of the grain size of the YIG and CCTO in the final properties of the composite. The samples were analyzed using X-Ray diffraction and scanning electron microscopy (SEM). Dielectric permittivity had been measured at 2.7 and 5.0 GHz, using the small perturbation theory.

Neural regularization jointly involving neurons and connections for robust image classification

This paper presents an integrated neural regularization method in fully-connected neural networks that jointly combines the cutting edge of regularization techniques; Dropout [1] and DropConnect [2]. With a small number of data set, trained feed-forward networks tend to show poor prediction performance on test data which has never been introduced while training. In order to reduce the overfitting, regularization methods commonly use only a sparse subset of their inputs. While a fully-connected layer with Dropout takes account of a randomly selected subset of hidden neurons with some probability, a layer with DropConnect only keeps a randomly selected subset of connections between neurons. It has been reported that their performances are dependent on domains. Image classification results show that the integrated method provides more degrees of freedom to achieve robust image recognition in the test phase. The experimental analyses on CIFAR-10 and one-hand gesture dataset show that the method provides the opportunity to improve classification performance.

Dielectric and magnetic properties of a yttrium ferrite/calcium copper titanate composite

ABSTRACT This work presents a study on the dielectric and magnetic properties of the yttrium ferrite/calcium copper titanate composites. Their structural properties were analyzed by X-ray diffraction, density, and scanning electron microscopy. Impedance and microwave measurements were performed to obtain the permittivity of the composites at different frequencies. The dielectric constant, at 300 K and below 1 MHz, shows a value of about 4 × 103 and at 2.4 GHz a value of 32 was measured. The generalized Looyenga mixture law was used to describe the variation of dielectric constant with the filler volume fraction in low and high frequency regions. Magnetic measurements shows a relation of hysteresis loops based on the concentration of yttrium ferrite. A maximum of 37 emu/g for the saturation magnetization was obtain at 300 K.

A New Approach for Dynamic Strategic Positioning in RoboCup Middle-Size League

Coordination in multi-robot or multi-agent systems has been receiving special attention in the last years and has a prominent role in the field of robotics. In the robotic soccer domain, the way that each team coordinates its robots, individually and together, in order to perform cooperative tasks is the base of its strategy and in large part dictates the success of the team in the game. In this paper we propose the use of Utility Maps to improve the strategic positioning of a robotic soccer team. Utility Maps are designed for different set pieces situations, making them more dynamic and easily adaptable to the different strategies used by the opponent teams. Our approach has been tested and successfully integrated in normal game situations to perform passes in free-play, allowing the robots to choose, in real-time, the best position to receive and pass the ball. The experimental results obtained, as well as the analysis of the team performance during the last RoboCup competition show that the use of Utility Maps increases the efficiency of the team strategy.