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Publicações

Publicações por CRIIS

2005

ADC Applications, Architectures and Terminology

Autores
Silva, JM; Mendonça, H;

Publicação
The International Series in Engineering and Computer Science - Dynamic Characterisation of Analogue-to-Digital Converters

Abstract

2005

Self localization of an autonomous robot: Using an EKF to merge odometry and vision based landmarks

Autores
Sousa, AJ; Costa, PJ; Moreira, AP; Carvalho, AS;

Publicação
ETFA 2005: 10th IEEE International Conference on Emerging Technologies and Factory Automation, Vol 1, Pts 1 and 2, Proceedings

Abstract
Localization is essential to modern autonomous robots in order to enable effective completion of complex tasks over possibly large distances in low structured environments. In this paper, a Extended Kalman Filter is used in order to implement self-localization. This is done by merging odometry and localization information, when available. The used landmarks are colored poles that can be recognized while the robot moves around performing normal tasks. This paper models measurements with very different characteristics in distance and angle to markers and shows results of the self-localization method. Results of simulations and real robot tests are shown.

2005

Architecture control and model identification of a Omni-Directional Mobile Robot

Autores
Conceicao, AS; Moreira, AP; Costa, PJ;

Publicação
2005 PORTUGUESE CONFERENCE ON ARTIFICIAL INTELLIGENCE, PROCEEDINGS

Abstract
This paper presents a architecture control and model identification of a onmi-Directional Mobile Robot It is divided into the three stages. Stage one proposes a procedure for dynamic model identification and control of the "motor + reduction + encoder" process of the Robot's Motors. Second, proposes the identification of a dynamic model for the whole mobile robot considering it as a multi-variable system. Third, presents a algorithm for perfect trajectory tracking of Omni-Directional Mobile Robots, based on restriction on motor's velocities. This algorithm combines the restriction on motor's velocities and the kinematic model of mobile robot to generate ideal drive velocities for the mobile robot to follow the trajectories correctly with the best possible performance.

2005

A Modular Approach to Real-Time Cork Classification Using Image Processing

Autores
Lima, JL; Costa, PG;

Publicação
ETFA 2005: 10TH IEEE INTERNATIONAL CONFERENCE ON EMERGING TECHNOLOGIES AND FACTORY AUTOMATION, VOL 2, PROCEEDINGS

Abstract
This paper's main purpose is to present an automatic vision assortment system for cork classification. Cork is a natural material that is used to seal wine bottles due to its reliability and its chemical and mechanic properties. A modular approach isolates the hard real-time sub problems. It includes some custom developed hardware and software. The developed and implemented system acquires images using a linear CCD camera, transmits that image over an Ethernet based network and processes that image to extract quantitative elements. This system can analyse and distinguish defects present on the surface of a cork-stopper and it is also possible to adapt it to other kinds of problems. The size, form and position of the defects are analysed and the stability of repeated measures is observed. This result allows us to validate the presented methodology.

2005

Modelling and simulation of artificial locomotion systems

Autores
Silva, MF; Machado, JAT; Lopes, AM;

Publicação
ROBOTICA

Abstract
This paper describes a simulation model for a multi-legged locomotion system with joints at the legs having viscous friction, flexibility and backlash. For that objective the robot prescribed motion is characterized in terms of several locomotion variables. Moreover, the robot body is divided into several segments in order to emulate the behaviour of an animal spine. The foot-ground interaction is modelled through a non-linear spring-dashpot system whose parameters are extracted from the studies on soil mechanics. To conclude, the performance of the developed simulation model is evaluated through a set of experiments while the robot leg joints are controlled using fractional order algorithms.

2005

Integer vs. fractional order control of a hexapod robot

Autores
Silva, MF; Machado, JAT; Lopes, AM;

Publicação
Climbing and Walking Robots

Abstract
This paper studies the performance of integer and fractional order controllers in a hexapod robot with joints at the legs having viscous friction and flexibility. For that objective the robot prescribed motion is characterized in terms of several locomotion variables. The controller performance is analised through the Nyquist stability criterion. A set of model-based experiments reveals the influence of the different controller implementations upon the proposed metrics.

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