Augusto Loureiro da Costa

Kepler Rapidly Rotating Giant Stars

Rapidly rotating giant stars are relatively rare and may represent important stages of stellar evolution, resulting from stellar coalescence of close binary systems or accretion of substellar companions by their hosting stars. In the present Letter, we report 17 giant stars observed in the scope of the Kepler space mission exhibiting rapid rotation behavior. For the first time, the abnormal rotational behavior for this puzzling family of stars is revealed by direct measurements of rotation, namely from photometric rotation period, exhibiting a very short rotation period with values ranging from 13 to 55 days. This finding points to remarkable surface rotation rates, up to 18 times the rotation of the Sun. These giants are combined with six others recently listed in the literature for mid-infrared (IR) diagnostics based on Wide-field Infrared Survey Explorer information, from which a trend for an IR excess is revealed for at least one-half of the stars, but at a level far lower than the dust excess emission shown by planet-bearing main-sequence stars.

From Reactive to Cognitive Agents: Extending Reinforcement Learning to Generate Symbolic Knowledge Bases

A new methodology for knowledge-based agents to learn from interactions with their environment is presented in this paper. This approach combines Reinforcement Learning and Knowledge-Based Systems. A Q-Learning algorithm obtains the optimal policy, which is automatically coded into a symbolic rule base, using first-order logic as knowledge representation formalism. The knowledge base was embedded in an omnidirectional mobile robot, making it able to navigate autonomously in unpredictable environments with obstacles using the same knowledge base. Additionally, a method of space abstraction based in human reasoning was formalized to reduce the number of complex environment states and to accelerate the learning. The experimental results of autonomous navigation executed by the real robot are also presented here.

Embedding a concurrent autonomous agent in a microcontrollers network

In this paper, a microcontroller heterogeneous network is proposed to embed a concurrent autonomous agent. The network was designed to fit the concurrency requirements of the cognitive model of the aforementioned agent. The architecture of the agent comprises three levels, namely, the reactive level, instinctive level and the cognitive level, which runs concurrently. The reactive level is embedded in a PSoC 5LP, consisting of behaviours created over a embedded kinematic controller. The instinctive level runs in a mbed NXP LPC1768, which receives perceptions from and sends the active behaviour to the reactive level through a CAN bus. And The cognitive level runs on a DNP/2486 which, in turn, receives symbolic information from and sends new local goals to instinctive level through an Ethernet network. Finally, the architecture used in the experiments is presented, followed by the results.

An architecture of sensor fusion for spatial location of objects in mobile robotics

Each part of a mobile robot has particular aspects of its own, which must be integrated in order to successfully conclude a specific task. Among these parts, sensing enables to construct a representation of landmarks of the surroundings with the goal of supplying relevant information for the robot’s navigation. The present work describes the architecture of a perception system based on data fusion from a CMOS camera and distance sensors. The aim of the proposed architecture is the spatial location of objects on a soccer field. An SVM is used for both recognition and object location and the process of fusion is made by means of a fuzzy system, using a TSK model.

A new methodology to teach electrical engineering using product development projects

Nowadays, it is necessary to change the way engineering is being taught to increase not only students interest in the classroom, but also the enrolment of new students in engineering courses. This paper describes how a new methodology to teach engineering using product development projects is been adapted, from previous positive results in two laboratories, to be used in the classroom. An example of this methodology describing the design of a Robotic Musical Instrument is given. It is expected that, by using this methodology, a more interactive and motivational environment can be created, where students could not only acquire knowledge, competences and skills, but would also experience an integrated and coherent view of the engineering process.

Recognition of Affective State for Austist from Stereotyped Gestures

Autists may exhibit difficulty in interaction (social and communication) with others and also stereotyped gestures. Thus, autists have difficulty to recognize and to express emotions. Human-Robot Interaction ( HRI ) researches have contributed with robotic devices able to be mediator among autist, therapists and parents. The stereotyped behaviors of these individuals are due to their defense mechanism from of their hypersensitivity. The affective state of a person can be quantify from poses and gestures. This paper proposes a system is able to infer the defense level of autists from their stereotyped gestures. This system is part of the socially assistive robot project calledHiBot . The proposed system consist of two cognitive subsystems: Hidden Markov Models (HMM ), in order to determine the stereotyped gesture, and Fuzzy Inference System ( FIS), to infer activation level of these gestures. The results of these simulations show this approach is able to infer the defense level for an task or the presence of the robot.

Real-time microprocessed system applied to mobile robots control

This paper presents a low cost micro-processed system developed for real-time control of omnidirectional mobile robots. The control strategy is designed on cascade form, being used in a lower level, discrete PI for control of wheels speed, and at a higher level, a kinematic controller for the acquisition of poses references for the robots. The central processing unit is designed with the microcontroller PIC32 and supervisory system is implemented through software Lazarus IDE running under the Linux platform. Practical results are provided to demonstrate the systems performance on real-time trajectory tracking.

COOPERATIVE MOBILE ROBOTS: A COGNITIVE MULTI-AGENT APPROACH

Abstract Mobile Robots and Autonomous Agents are very similar concepts that present several common aspects. In particular, Multi-Robot Systems that are intended to perform cooperative tasks can be seen as Multi-Agent Systems. This paper presents the implementation of a distributed control for mobile multi-robot system that perform cooperative tasks, under soft real-time restriction and using the best effort approach, based on a Multi-Agent approach.

The Berimbot: A Robotic Musical Instrument as an Outreach Tool for the Popularization of Science and Technology

The purpose of this article is to describe an outreach program based on the engineering design of a robotic musical instrument aimed to the segment of the population not served by traditional academic initiatives or outreach programs. It aims to contribute to develop the interest among children and youngsters in pursuing scientific and technology careers and also mitigating science illiteracy among the general public. The program consists in a keynote showing the various phases undertaken, people involved and the knowledge and skills needed to build the robotic musical instrument. The concepts of teamwork, consulting and multidisciplinarity are also examined. The presentation includes a musical performance.

Propositional Temporal Logic for planning in an embedded Concurrent Autonomous Agent

In this paper, a Propositional Temporal Logic (PTL) inference engine is implemented in the cognitive level of a Concurrent Autonomous Agent (CAA). The hardware architecture of the system is an embedded microcontrollers network designed to fit the concurrency requirements of the cognitive model of the aforementioned agent. The architecture of the agent comprises three levels, namely, the reactive level, instinctive level and the cognitive level, which runs concurrently. The reactive level is embedded in a PSoC 5LP, consisting of behaviours created over a embedded kinematic controller. The instinctive level runs in an ARM mbed, which receives perceptions from and sends the active behaviour to the reactive level through a CAN bus. This level uses a Knowledge Based System (KBS) with First Order Logic (FOL) as automatic reasoning mechanism. The cognitive level runs an implementation of the METATEM algorithm on a DNP/2486 which, in turn, receives symbolic information from the instinctive level to update its logical world model. It also sends new local goals to instinctive level through an Ethernet network. Finally, the architecture used in the experiments is presented, followed by the results.