A brainstem-like modulation approach for gait transition in a quadruped robot

The ability to traverse a wide variety of terrains while walking is basically a requirement for performing useful tasks in our human centric world. In this article, we propose a bio-inspired robotic controller able to generate locomotion and to easily switch between different type of gaits. In order to improve the robot stability and response while locomoting, we adjust both the duty factor and the interlimb phase relationships, according to the velocities. We extend previous work, by applying nonlinear oscillators to generate the rhythmic locomotor movements for a quadruped robot, similarly to the biological counterparts. The generated trajectories are modulated by a drive signal, that modifies the oscillator frequency, amplitude and the coupling parameters among the oscillators, proportionally to the drive signal strength. By increasing the drive signal, locomotion can be elicited and velocity increased while switching to the appropriate gaits. This drive signal can be specified according to sensory information or set a priori. The implementation of the central pattern generator network and the activity modulation layer is shown in simulation and in an AIBO robot

Impact of discrete corrections in a modular approach for trajectory generation in quadruped robots

Online generation of trajectories in robots is a very complex task that involves the combination of different types of movements, i.e., distinct motor primitives. The later are used to model complex behaviors in robots, such as locomotion in irregular terrain and obstacle avoidance. In this paper, we consider two motor primitives: rhythmic and discrete. We study the effect on the robots’ gaits of superimposing the two motor primitives, considering two distinct types of coupling. Additionally, we simulate two scenarios, where the discrete primitive is inserted in all of the four limbs, or is inserted in ipsilateral pairs of limbs. Numerical results show that amplitude and frequency of the periodic solutions, corresponding to the gaits trot and pace, are almost constant for diffusive and synaptic couplings.CP was supported by Research funded by the European Regional Development Fund through the programme COMPETE and by the Portuguese Government through the FCT Fundacao para a Ciencia e a Tecnologia under the project PEst-C/MAT/UI0144/2011. This work was also funded by FEDER Funding supported by the Operational Program Competitive Factors COMPETE and National Funding supported by the FCT - Portuguese Science Foundation through project PTDC/EEACRO/100655/2008

GeoloGIS-BH: An Information System for Using the Built Heritage for Geological Teaching

There are examples of using stones of the cultural heritage for teaching purposes. Information systems have found several potential uses in the promotion and preservation of cultural heritage. In this paper is considered the conceptual framework of an information system concerning features of geological interest (FGI) in the built heritage (without any consideration in terms of its software implementation). This FGI concept is used here in a very wide sense to encompass characteristics of geological materials that can be recognized with the naked eye and analogies of geological processes in the built environment. Two perspectives are considered for information organization: occurrences of FGIs in the built heritage (more suitable for Earth Sciences teaching) and FGIs as components of built heritage elements (more suitable for humanities teaching). The main issue that arises from the ensuing discussion was found to be the findability of a given FGI, depending on its visual contrast and the characteristics of the built heritage element. It is argued that, in this way, geological concepts can contribute to the promotion and conservation of the built heritageThis work is included in the activities of the project Lab2PT - Landscapes, Heritage and Territory laboratory - AUR/04509, which has financial support of the Portuguese Fundação para a Ciência e a Tecnologia through national funds and when applicable of the FEDER co-financing, in the aim of the new partnership agreement PT2020 and COMPETE2020 - POCI 01 0145 FEDER 007528.info:eu-repo/semantics/publishedVersio

Monitorização de campo de águas subterrâneas

Existem vários exemplos nos estudos geológicos de caraterísticas físicas que são utilizadas para investigar modificações químicas, como seja a massa volúmica (que em séries isomórficas pode mostrar relações aproximadamente lineares com a variação entre dois termos químicos extremos) e a radiação gama que reflete as variações das atividades específicas de radioisótopos. No estudo das águas subterrâneas, vários parâmetros que podem ser designados como globais [1] podem ser medidos no campo para o controle de variações que refletem mudanças químicas (nomeadamente por efeitos de poluição) mas tendo em consideração as limitações dos mesmos (nomeadamente que várias substâncias químicas que podem provocar a mesma variação das propriedades físicas). Destacamos (por terem sido o objeto de medição) o pH, o Eh (relacionado com reações oxidação-redução) e a condutividade elétrica (está última está relacionada com a presença de iões). Apesar das limitações já referidas, estas medições são inestimáveis pela sua celeridade (podem, inclusivamente, ser todas medidas por um único equipamento em questão de minutos) e por poderem ser realizadas no campo, fator crítico para qualquer estudo de objetos geológicos. A simplicidade e celeridade destas medições permitem a sua utilização para uma monitorização de elevada frequência, permitindo definir tendências e servir como critérios de ação para a realização de análises de laboratório mais completa (sem dispensar outros critérios de amostragem, nomeadamente em termos de periocidade). Estas informações podem ser integradas em ambiente SIG para avaliações regionais e para investigar tendências espaciotemporais. Neste estudo comparam-se medições de pH, Eh e condutividade elétrica realizadas num intervalo de tempo semelhante em três poços e quatro nascentes situadas em três concelhos do distrito de Braga (Amares, Guimarães e Vieira do Minho). Estas medições foram acompanhadas, para efeitos de discussão e pela sua relação com os fatores que afetam o quimismo das águas, de medições de temperatura e (no caso das nascentes) de estimativas do caudal. As medições realizadas permitem a comparação entre parâmetros e entre locais, investigando correlações (coeficientes de Pearson e Spearman), assim como análise multivariada de tipo grupal (tendo em consideração que os parâmetros apresentam diferentes escalas de medição, foram utilizadas os valores normalizados para média igual a zero e desvio-padrão igual a um)O Lab2PT- Laboratório de Paisagens, Património e Território - AUR/04509 é financiado pela FCT através de fundos nacionais e quando aplicável do cofinanciamento do FEDER, no âmbito dos novos acordos de parceria PT2020 e COMPETE 2020 – POCI-01-0145-FEDER-007528.info:eu-repo/semantics/publishedVersio

A new CPG model for the generation of modular trajectories for hexapod robots

Legged robots are often used in a large variety of tasks, in different environments. Nevertheless, due to the large number of degrees-of-freedom to be controlled, online generation of trajectories in these robots is very complex. In this paper, we consider a modular approach to online generation of trajectories, based on biological concepts, namely Central Pattern Generators (CPGs). We introduce a new CPG model for hexapod robots’ rhythms, based in the work of Golubitsky et al (1998). Each neuron/oscillator in the CPG consists of two modules/primitives: rhythmic and discrete. We study the effect on the robots’ gaits of superimposing the two motor primitives, considering two distinct types of coupling.We conclude, from the simulation results, that the amplitude and frequency of periodic solutions, identified with hexapods’ tripod and metachronal gaits, remain constant for the two couplings, after insertion of the discrete part.CP was supported by Research funded by the European Regional Development Fund through the programme COMPETE and by the Portuguese Government through the FCT Fundacao para a Ciencia e a Tecnologia under the project PEst-C/MAT/UI0144/2011. This work was also funded by FEDER Funding supported by the Operational Program Competitive Factors COMPETE and National Funding supported by the FCT - Portuguese Science Foundation through project PTDC/EEACRO/100655/2008

Operation modes for the electric vehicle in smart grids and smart homes: present and proposed modes

This paper presents the main operation modes for an electric vehicle (EV) battery charger framed in smart grids and smart homes, i.e., are discussed the present-day and are proposed new operation modes that can represent an asset towards EV adoption. Besides the well-known grid to vehicle (G2V) and vehicle to grid (V2G), this paper proposes two new operation modes: Home-to-vehicle (H2V), where the EV battery charger current is controlled according to the current consumption of the electrical appliances of the home (this operation mode is combined with the G2V and V2G); Vehicle-for-grid (V4G), where the EV battery charger is used for compensating current harmonics or reactive power, simultaneously with the G2V and V2G operation modes. The vehicle-to-home (V2H) operation mode, where the EV can operate as a power source in isolated systems or as an off-line uninterruptible power supply to feed priority appliances of the home during power outages of the electrical grid is presented in this paper framed with the other operation modes. These five operation modes were validated through experimental results using a developed 3.6 kW bidirectional EV battery charger prototype, which was specially designed for these operation modes. The paper describes the developed EV battery charger prototype, detailing the power theory and the voltage and current control strategies used in the control system. The paper presents experimental results for the various operation modes, both in steady-state and during transients

A modular approach for trajectory generation in biped robots

Robot locomotion has been a major research issue in the last decades. In particular, humanoid robotics has had a major breakthrough. The motivation for this study is that bipedal locomotion is superior to wheeled approaches on real terrain and situations where robots accompany or replace humans. Some examples are, on the development of human assisting device, such as prosthetics, orthotics, and devices for rehabilitation, rescue of wounded troops, help at the office, help as maidens, accompany and assist elderly people, amongst others. Generating trajectories online for these robots is a hard process, that includes different types of movements, i.e., distinct motor primitives. In this paper, we consider two motor primitives: rhythmic and discrete.We study the effect on a bipeds robots’ gaits of inserting the discrete part as an offset of the rhythmic primitive, in synaptic and diffusive couplings. Numerical results show that amplitude and frequency of the periodic solution, corresponding to the gait run are almost constant in all cases studied here.(undefined

Descrição de um surto de intoxicação por cianobactérias (algas verdes-azuis) em bovinos no Alentejo

Suspeita de hepatoxicidade provocada por cianotoxinas, num surto de morte súbita em 25 bovinos numa exploração com 54 vacas de carne em Almodôvar, Alentejo.N/