Percorrer por autor "Pires, E. J. Solteiro"
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- An evolutionary approach to robot structure and trajectoryPublication . Pires, E. J. Solteiro; Tenreiro Machado, J. A.; Oliveira, P. B. de MouraThis paper proposes a genetic algorithm to generate a robot structure and the required manipulating trajectories. The objective is to minimize the space/time ripple in the workspace, while optimizing the mechanical structure.
- An evolutionary optimization for robotic manipulatorsPublication . Pires, E. J. Solteiro; Tenreiro Machado, J. A.; Oliveira, P. B. de MouraThis work proposes a real time algorithm to generate a trajectory for a 2-link planar robotic manipulator. The objective is to minimize the space/time ripple and the energy requirements or the time duration in the robot trajectories. The proposed method uses an off-line genetic algorithm to calculate every possible trajectory between all cells of the workspace grid. The resultant trajectories are saved in several trees. Then any trajectory resquested is constructed, in real time, from these trees. The article presents the results for several experiments.
- Aplication of fractional algoritms in the control of an helicopter systemPublication . Coelho, J.; Neto, R. Matos; Lebres, C.; Fachada, H.; Ferreira, N. M. Fonseca; Pires, E. J. Solteiro; Tenreiro Machado, J. A.This paper compares the application of fractional and integer order controllers for a laboratory helicopter twin rotor MIMO system using the MatLab package.
- Application of fractional algorithms in the control of a twin rotor multiple input-multiple output systemPublication . Coelho, J.; Neto, R. Matos; Lebres, C.; Santos, Victor; Ferreira, N. M. Fonseca; Pires, E. J. Solteiro; Tenreiro Machado, J. A.This paper presents the modelling and control of a laboratory helicopter twin rotor MIMO system using the MatLab package. Firstly, we provide an overview of the system model, secondly, we compare the behaviour of fractional and integer order controllers used a PSO algorithm for the controller optimization in order to obtain the minimum error. Finally, we analyse the system performance and the results obtained with the real helicopter show that fractional algorithms are smoother than conventional PID. Both controllers reveal good output responses but the PID needs more energy to perform the same task.
- Applications of fractional calculus in electrical and computer engineeringPublication . Tenreiro Machado, J. A.; Silva, Manuel; Barbosa, Ramiro; Jesus, Isabel S.; Reis, Cecília; Marcos, Maria da Graça; M. Afonso, Luís; Lima, Miguel F. M.; Pires, E. J. Solteiro; Ferreira, N. M. FonsecaFractional Calculus (FC) goes back to the beginning of the theory of differential calculus. Nevertheless, the application of FC just emerged in the last two decades, due to the progress in the area of chaos that revealed subtle relationships with the FC concepts. In the field of dynamical systems theory some work has been carried out but the proposed models and algorithms are still in a preliminary stage of establishment. Having these ideas in mind, the paper discusses a FC perspective in the study of the dynamics and control of several systems. This article illustrates several applications of fractional calculus in science and 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 the fields of controller tuning, electrical systems, digital circuit synthesis, evolutionary computing, redundant robots, legged robots, robotic manipulators, nonlinear friction and financial modeling.
- Automated design of microwave discrete tuning differential capacitance circuits in Si-integrated technologiesPublication . Mendes, Luís; Pires, E. J. Solteiro; Vaz, João C.; Rosário, Maria J.; Oliveira, P. B. Moura; Machado, J. A. TenreiroA genetic algorithm used to design radio-frequency binary-weighted differential switched capacitor arrays (RFDSCAs) is presented in this article. The algorithm provides a set of circuits all having the same maximum performance. This article also describes the design, implementation, and measurements results of a 0.25 lm BiCMOS 3-bit RFDSCA. The experimental results show that the circuit presents the expected performance up to 40 GHz. The similarity between the evolutionary solutions, circuit simulations, and measured results indicates that the genetic synthesis method is a very useful tool for designing optimum performance RFDSCAs.
- Automated Synthesis Procedure of RF Discrete Tuning Differential Capacitance CircuitsPublication . Mendes, Luís; Pires, E. J. Solteiro; Vaz, João C.; Rosário, Maria J.; Oliveira, P. B. de Moura; Machado, J. A. Tenreiro; Ferreira, N. M. FonsecaThe paper presents a RFDSCA automated synthesis procedure. This algorithm determines several RFDSCA circuits from the top-level system specifications all with the same maximum performance. The genetic synthesis tool optimizes a fitness function proportional to the RFDSCA quality factor and uses the epsiv-concept and maximin sorting scheme to achieve a set of solutions well distributed along a non-dominated front. To confirm the results of the algorithm, three RFDSCAs were simulated in SpectreRF and one of them was implemented and tested. The design used a 0.25 mum BiCMOS process. All the results (synthesized, simulated and measured) are very close, which indicate that the genetic synthesis method is a very useful tool to design optimum performance RFDSCAs.
- Automated synthesis procedure of RF discrete tuning differential capacitance circuitsPublication . Mendes, Luís; Pires, E. J. Solteiro; Vaz, João C.; Rosário, Maria J.; Oliveira, P. B. Moura; Machado, J. A. Tenreiro; Ferreira, Nuno M. F.The paper presents a RFDSCA automated synthesis procedure. This algorithm determines several RFDSCA circuits from the top-level system specifications all with the same maximum performance. The genetic synthesis tool optimizes a fitness function proportional to the RFDSCA quality factor and uses the epsiv-concept and maximin sorting scheme to achieve a set of solutions well distributed along a non-dominated front. To confirm the results of the algorithm, three RFDSCAs were simulated in SpectreRF and one of them was implemented and tested. The design used a 0.25 mum BiCMOS process. All the results (synthesized, simulated and measured) are very close, which indicate that the genetic synthesis method is a very useful tool to design optimum performance RFDSCAs.
- Control optimization of a robotic birdPublication . Couceiro, M. S.; Ferreira, N. M. Fonseca; Mendes, R.; Pires, E. J. Solteiro; Machado, J. A. TenreiroIn this paper it is studied the modeling and control of a robotic bird. The results are positive for the design and construction of flying robots and a new generation of airplanes developed to the similarity of flying animals. Once implemented the dynamic models studied, we will study different movement planning routines and the dynamic stability to adopt, the development of computational simulation based on the dynamic of the robotic bird should allow testing strategies and different kind of control such as integer and fractional controllers. It is studied different kindo of optimization algorithms in order to achieve the best algorithm of control to use in our model. We compare the Gradient Descent optimization method to the PSO algorithm presenting somo time response parameters of our system under the action of different controllers. Firstly, we provide an overview of the system model; secondly, we compare the behaviour of fractional and integer order controllers using different algorithm for the controller optimization in order to obtain the menium error.
- Dynamical modelling of a genetic algorithmPublication . Pires, E. J. Solteiro; Machado, J. A. Tenreiro; Oliveira, P. B. MouraThis work addresses the signal propagation and the fractional-order dynamics during the evolution of a genetic algorithm (GA). In order to investigate the phenomena involved in the GA population evolution, the mutation is exposed to excitation perturbations during some generations and the corresponding fitness variations are evaluated. Three distinct fitness functions are used to study their influence in the GA dynamics. The input and output signals are studied revealing a fractional-order dynamic evolution, characteristic of a long-term system memory.