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Publications

Publications by CRIIS

2004

Gait selection for quadruped and hexapod walking systems

Authors
Silva, MF; Machado, JAT; Lopes, AM; Tar, JK;

Publication
ICCC 2004: SECOND IEEE INTERNATIONAL CONFERENCE ON COMPUTATIONAL CYBERNETICS, PROCEEDINGS

Abstract
This paper studies periodic gaits of quadruped and hexapod locomotion systems. The purpose is to determine the best set of gait and locomotion variables for different robot velocities based on the system dynamics during walking. In this perspective, several performance measures are formulated and a set of experiments that reveal the influence of the gait and locomotion variables upon those proposed indices are performed.

2004

Topological navigation in configuration space applied to soccer robots

Authors
Neto, G; Costelha, H; Lima, P;

Publication
ROBOCUP 2003: ROBOT SOCCER WORLD CUP VII

Abstract
This paper describes a topological navigation system, based on the description of key-places by a reduced number of parameters that represent images associated to specific locations in configuration space, and the application of the developed system to robotic soccer, through the implementation of the developed algorithms to RoboCup Middle-Size League (MSL) robots, under the scope of the SocRob project (Soccer Robots or Society of Robots). A topological map is associated with a graph, where each node corresponds to a key-place. Using this approach, navigation is reduced to a graph path search. Principal Components Analysis was used to represent key-places from pre-acquired images and to recognize them at navigation time. The method revealed a promising performance navigating between key-places and proved to adapt to different graphs. Furthermore, it leads to a robot programming language based on qualitative descriptions of the target locations in configuration space (e.g., Near Blue Coal with the Goal on its Left). Simulation results of the method application are presented, using a realistic simulator.

2004

Robot Trajectory Planning Using Multi-objective Genetic Algorithm Optimization

Authors
Pires, EJS; Machado, JAT; Oliveira, PBdM;

Publication
Genetic and Evolutionary Computation - GECCO 2004, Genetic and Evolutionary Computation Conference, Seattle, WA, USA, June 26-30, 2004, Proceedings, Part I

Abstract

2004

Multi-objective genetic manipulator trajectory planner

Authors
Pires, EJS; Oliveira, PBD; Machado, JAT;

Publication
APPLICATIONS OF EVOLUTIONARY COMPUTING

Abstract
This paper proposes a multi-objective genetic algorithm to optimize a manipulator trajectory. The planner has several objectives namely the minimization of the space and join arm displacements and the energy required in the trajectory, without colliding with any obstacles in the workspace. Simulations results are presented for robots with two and three degrees of freedom, considering the optimization of two and three objectives.

2004

Robot trajectory planning using multi-objective genetic algorithm optimization

Authors
Pires, EJS; Machado, JAT; Oliveira, PBD;

Publication
GENETIC AND EVOLUTIONARY COMPUTATION - GECCO 2004, PT 1, PROCEEDINGS

Abstract
Generating manipulator trajectories considering multiple objectives and obstacle avoidance is a non trivial optimization problem. In this paper a multi-objective genetic algorithm is proposed to address this problem. Multiple criteria are optimized up to five simultaneous objectives. Simulations results are presented for robots with two and three degrees of freedom, considering two and five objectives optimization. A subsequent analysis of the solutions distribution along the converged non-dominated Pareto front is carried out, in terms of the achieved diversity.

2004

Modeling, simulation and testing of a silicon soil moisture sensor based on the dual-probe heat-pulse method

Authors
Valente, A; Morais, R; Couto, C; Correia, JH;

Publication
SENSORS AND ACTUATORS A-PHYSICAL

Abstract
A silicon soil moisture sensor, based in the dual-probe heat-pulse (DPHP) method, was modeled, simulated and tested for achieving, with low-cost, accurate and reliable measurements. This method is based on the application of a heat pulse during a fixed interval of time. The maximum rise in temperature (DeltaT(M)) is monitored by the measurement probe, placed at a certain distance of the heater source. A low-cost high-performance and small temperature sensor (a dynamic V-pTAT generator) was designed and fabricated to be placed into the probe which have 0.912 mm inner diameter and 20 mm long. If one considers the range of water contents, ratio of water mass to dry soil mass, in a typical agricultural soil (0.05-0.35 m(3) M-3), the average sensitivity of the dual probe is about 1.95 degreesC per unit change (m(3) M-3) in water content for q = 400 Jm(-1).

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