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Publicações

Publicações por Eduardo Pires

2011

Complete Dynamic Modeling of a Stewart Platform Using the Generalized Momentum Approach

Autores
Lopes, AM; Pires, EJS;

Publicação
NONLINEAR SCIENCE AND COMPLEXITY

Abstract
Dynamic modeling is of great importance regarding computer simulation and advanced control of parallel manipulators. Dynamic modeling of parallel manipulators presents an inherent complexity, mainly due to system closed-loop structure and kinematic constraints. In this paper an approach based on the manipulator generalized momentum is explored and applied to the dynamic modeling of a Stewart platform. The generalized momentum is used to compute the kinetic component of the generalized force acting on each manipulator rigid body. Analytic expressions for the rigid bodies' inertia and Coriolis and centripetal terms matrices are obtained, which can be added, as they are expressed in the same frame. Gravitational part of the generalized force is obtained using the manipulator potential energy.

2007

Towards the PID beta control of heat diffusion systems

Autores
Jesus, IS; Machado, JAT; Barbosa, RS; Pires, ESS;

Publicação
PROCEEDINGS OF THE 7TH INTERNATIONAL CONFERENCE ON INTELLIGENT SYSTEMS DESIGN AND APPLICATIONS

Abstract
In this work we study a heat diffusion system on a fractional calculus perspective. Several fractional PID tuning methodologies are investigated and compared. The simulations demonstrate the good performance of the proposed fractional algorithm.

2007

Automated design of radio-frequency single-ended switched capacitor arrays using genetic algorithms

Autores
Mendes, L; Solteiro Pires, EJS; Vaz, JC; Rosario, MJ;

Publicação
2007 50TH MIDWEST SYMPOSIUM ON CIRCUITS AND SYSTEMS, VOLS 1-3

Abstract
This paper presents an automated synthesis procedure to design radio-frequency and microwave binary-weighted single-ended switched capacitor arrays (RFSSCAs) from user top-level specifications to components sizes. The method relies on closed-form symbolic mathematical expressions of the input impedance and quality factor of the RFSSCA. The genetic synthesis tool optimizes a fitness function based on user-specified performance constraints. The method determines several optimal solutions, which are completely independent of the starting point. Moreover, infeasible specifications are unambiguously detected. To validate the proposed design algorithm, two RFSSCAs are synthesized in a 0.35 mu m CMOS technology and verified by the SpectreRF simulator of the Cadence design environment. The results show that the synthesis and simulation outcomes are in very good agreement.

2007

An evolutionary synthesis algorithm to design optimum performance CMOS RFSSCAs

Autores
Mendes, L; Pires, EJS; Vaz, JC; Rosario, MJ;

Publicação
2007 14TH IEEE INTERNATIONAL CONFERENCE ON ELECTRONICS, CIRCUITS AND SYSTEMS, VOLS 1-4

Abstract
An automated synthesis procedure, based on genetic algorithms, to design optimum performance Si-integrated radio-frequency and microwave binary-weighted single-ended switched capacitor arrays (RFSSCAs), is presented in this paper. The method determines the RFSSCA circuit size and the circuit components values from the top-level system specifications. The genetic synthesis tool optimizes a fitness function based on user-specified performance constraints. Besides that, the algorithm uses a sharing scheme in order to achieve a set of optimal solutions. The solutions set, obtained by the genetic algorithm, give to the designer the liberty of choosing several possible implementations maintaining the performance objective. To confirm the circuit solutions obtained by the algorithm, two RFSSCAs are synthesized in a 2-poly 4-metal 0.35 mu m standard CMOS technology. The circuit is then simulated in SpectreRF. Since the synthesized results are in very good agreement with the simulated outcomes, it can be stated that the proposed genetic synthesis method is a very useful tool to design optimum performance KFSSCAs.

2007

A high-performance digitally controlled LC oscillator for Ku-band applications

Autores
Mendes, L; Pires, EJS; Vaz, JC; Rosario, MJ;

Publicação
2007 14TH IEEE INTERNATIONAL CONFERENCE ON ELECTRONICS, CIRCUITS AND SYSTEMS, VOLS 1-4

Abstract
A 13.5-15.5 GHz low phase noise digitally controlled LC VCO, designed in a 015 mu m BiCMOS technology, is presented in this paper. The resonant circuit of the VCO uses a high performance radio-frequency differential binary-weighted switched capacitor array (RFDSCA) to cover the 2 GHz tuning band with a continuous tuning voltage of 5 V. The RFDSCA circuit was optimized using a new automated synthesis method in order to guarantee a VCO with minimum phase noise. The VCO presents a typical phase noise of -116 dB/Hz @ 1MHz and a maximum tuning sensitivity of 165 MHz/V. The VCO core works with a voltage supply of 3 V and has a current consumption of 5 mA. The results demonstrate the feasibility of implementing and using high performance RFDSCAs as digital tuning elements at operating frequencies up to tens of gigahertz.

1999

Trajectory planner for manipulators using genetic algorithms

Autores
Pires, EJS; Machado, JAT;

Publicação
Proceedings of the IEEE International Symposium on Assembly and Task Planning

Abstract
This paper proposes a genetic algorithm (GA) to generate trajectories for robotic manipulators. The objective is to minimize the ripple in the time evolution of robot positions and velocities. Moreover, the manipulator is required to reach a predefined goal without colliding with obstacles in the workspace. The article presents the results for several redundant and non-redundant robot manipulators.

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