Hybrid adaptive control of a dragonfly model

Dragonflies show unique and superior flight performances than most of other insect species and birds. They are equipped with two pairs of independently controlled wings granting an unmatchable flying performance and robustness. In this paper, it is presented an adaptive scheme controlling a nonlinear model inspired in a dragonfly-like robot. It is proposed a hybrid adaptive (HA) law for adjusting the parameters analyzing the tracking error. At the current stage of the project it is considered essential the development of computational simulation models based in the dynamics to test whether strategies or algorithms of control, parts of the system (such as different wing configurations, tail) as well as the complete system. The performance analysis proves the superiority of the HA law over the direct adaptive (DA) method in terms of faster and improved tracking and parameter convergence.

On the robustness of the slotine-Li and the FPT/SVD-based adaptive controllers

A comparative study concerning the robustness of a novel, Fixed Point Transformations/Singular Value Decomposition (FPT/SVD)-based adaptive controller and the Slotine-Li (S&L) approach is given by numerical simulations using a three degree of freedom paradigm of typical Classical Mechanical systems, the cart + double pendulum. The effects of the imprecision of the available dynamical model, presence of dynamic friction at the axles of the drives, and the existence of external disturbance forces unknown and not modeled by the controller are considered. While the Slotine-Li approach tries to identify the parameters of the formally precise, available analytical model of the controlled system with the implicit assumption that the generalized forces are precisely known, the novel one makes do with a very rough, affine form and a formally more precise approximate model of that system, and uses temporal observations of its desired vs. realized responses. Furthermore, it does not assume the lack of unknown perturbations caused either by internal friction and/or external disturbances. Its another advantage is that it needs the execution of the SVD as a relatively time-consuming operation on a grid of a rough system-model only one time, before the commencement of the control cycle within which it works only with simple computations. The simulation examples exemplify the superiority of the FPT/SVD-based control that otherwise has the deficiency that it can get out of the region of its convergence. Therefore its design and use needs preliminary simulation investigations. However, the simulations also exemplify that its convergence can be guaranteed for various practical purposes.

Consequences of intercultural practices in Miguel Sousa Tavares' Equator

This article involves the analysis of a case-study, so I have chosen Equador by the Portuguese author Miguel Sousa Tavares. His book recreates the story of Sao Tome and Principe's people living under strict circumstances, while belonging to the Portuguese empire as one of its overseas' province. The forthcoming lines contain an approach to interculturality by analyzing these concrete circumstances. These lines also describe and study the differences between cultures - the Portuguese, as a European culture, and the Equatorial, as a colonized people's culture. The theme is old, but always relevant: the clash of value systems and the impossibility of forcibly overlaying one society on another. Slavery has existed as a common practice in most civilizations throughout history, based upon the superiority of a human being towards another. In socially hierarchized communities slavery was a major principle, almost a need. That way, some would benefit from exuberating privileges but many others only from hard working and giving their freedom up to be mistreated instead. In order to have a socially structured community, they were to be seriously and consciously neglected.