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- Neural control of an autonomous robotPublication . Pinto, Adriano; Barbosa, Ramiro S.; Silva, Manuel SantosThis article aims to apply the concepts associated with artificial neural networks (ANN) in the control of an autonomous robot system that is intended to be used in competitions of robots. The robot was tested in several arbitrary paths in order to verify its effectiveness. The results show that the robot performed the tasks with success. Moreover, in the case of arbitrary paths the ANN control outperforms other methodologies, such as fuzzy logic control (FLC).
- Step count algorithm adapted to indoor localizationPublication . Terra, Rui; Figueiredo, Lino; Barbosa, Ramiro; Anacleto, RicardoThis paper presents a step count algorithm designed to work in real-time using low computational power. This proposal is our first step for the development of an indoor navigation system, based on Pedestrian Dead Reckoning (PDR). We present two approaches to solve this problem and compare them based in their error on step counting, as well as, the capability of their use in a real time system.
- Traveled Distance Estimation Algorithm for Indoor LocalizationPublication . Terra, Rui; Figueiredo, Lino; Barbosa, Ramiro S.; Anacleto, RicardoThis paper presents an ankle mounted Inertial Navigation System (INS) used to estimate the distance traveled by a pedestrian. This distance is estimated by the number of steps given by the user. The proposed method is based on force sensors to enhance the results obtained from an INS. Experimental results have shown that, depending on the step frequency, the traveled distance error varies between 2.7% and 5.6%.
- Realization of fractional-order controllers: analysis, synthesis and application to the velocity control of a servo systemPublication . Barbosa, Ramiro S.; Jesus, Isabel S.; Silva, Manuel F.; Machado, J. A. TenreiroThe synthesis and application of fractional-order controllers is now an active research field. This article investigates the use of fractional-order PID controllers in the velocity control of an experimental modular servo system. The systern consists of a digital servomechanism and open-architecture software environment for real-time control experiments using MATLAB/Simulink. Different tuning methods will be employed, such as heuristics based on the well-known Ziegler Nichols rules, techniques based on Bode’s ideal transfer function and optimization tuning methods. Experimental responses obtained from the application of the several fractional-order controllers are presented and analyzed. The effectiveness and superior performance of the proposed algorithms are also compared with classical integer-order PID controllers.
- Control of a heat diffusion system through a fractional order nonlinear algorithmPublication . Jesus, Isabel S.; Tenreiro Machado, J. A.; Barbosa, RamiroThe application of the FC concepts has increased significantly in different fields of science and engineering, because FC captures properties that classical integer order models neglect. This paper studies a heat diffusion system, that is described through the fractional operator s0.5, under the control of a fractional nonlinear algorithm. The tuning of the algorithm follows the optimization of performance control indices. The results demonstrate the good performance of the proposed controller.
- Development of a genetic algorithm for the optimization of hexapod robot parametersPublication . Silva, Manuel; Barbosa, Ramiro; Tenreiro Machado, J. A.Legged robots allow the locomotion on terrains inaccessible to other type of vehicles because they do not need a continuous support surface. Different strategies have been adopted for the optimization of these systems, during their design and construction phases, and during their operation. Among the different optimization criteria followed by different authors, it is possible to find issues related to energy efficiency, stability, speed, comfort, mobility and environmental impact. Evolutionary strategies are a way to ”imitate nature” replicating the process that nature designed for the generation and evolution of species. The objective of this paper is to present a genetic algorithm, running over a simulation application of legged robots, which allows the optimization of several parameters of the robot model and of its gaits, for different locomotion speeds.
- Fractional describing function analysis of systems with backlash and impact phenomenaPublication . Barbosa, Ramiro; Tenreiro Machado, J. A.This paper analyses the dynamical properties of systems with backlash and impact phenomena based on the describing function method. It is shown that this type of nonlinearity can be analyzed in the perspective of the fractional calculus theory. The fractional-order dynamics is illustrated using the Nyquist plot and the results are compared with those of standard models.
- Application of Fractional Calculus in Control and ElectromagnetismPublication . Tenreiro Machado, J. A.; Barbosa, Ramiro; Jesus, Isabel S.; Silva, Manuel; Reis, Cecília; Figueiredo, LinoThis article illustrates two applications of fractional calculus (FC) in engineering. It has been recognized the advantageous use of this mathematical tool in the modeling and control of many dynamical systems. In this perspective, this paper investigates the use of FC in PID tuning and electrical potential.
- Design of Digital Fractional-Order Integrators and Differentiators by Least SquaresPublication . Barbosa, Ramiro S.; Machado, J. A. Tenreiro; Ferreira, Isabel M.In this paper we develop a method for obtaining digital rational approximations (IIR filters) to fractional-order operators of type sα, where α ∈ . The proposed method is based on the least-squares (LS) minimization between the impulse responses of the digital fractional-order integrator/differentiator and of the rational-fraction approximation. The results reveal that the LS approach gives similar or superior approximations in comparison with other methods. The effectiveness of the method is demonstrated both in the time and frequency domains through an illustrative example.
- Fractional Control of Dynamic SystemsPublication . Barbosa, Ramiro S.; Machado, J. A. TenreiroThe concepts involved with fractional calculus (FC) theory are applied in almost all areas of science and engineering. Its ability to yield superior modeling and control in many dynamical systems is well recognized. In this article, we will introduce the fundamental aspects associated with the application os FC to the control of dynamic systems.