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Publications

Publications by António Paulo Moreira

2017

Dc motor educational kit: A teaching aid in control theory

Authors
Moreira, AP; Costa, P; Gonçalves, J; Faria, BM;

Publication
Lecture Notes in Electrical Engineering

Abstract
This paper describes a laboratory control theory experiment supported by the use of a DCMotor Educational Kit. The impact, as a teaching aid, of the proposed laboratory control experiment is evaluated, having in mind the student’s feedback. The DC motor that is used in the developed educational Kit is the EMG30, being a low cost 12V motor equipped with encoders and a 30:1 reduction gearbox. The experiment is based on real hardware and on simulation, using the SimTwo realistic simulation software. In order to implement the realistic simulation the EMG30model was obtained. Students’ feedback was acquired using a questionnaire and the results confirmed the importance given to these practical experiments. © Springer International Publishing Switzerland 2017.

2014

A Flow-based Motion Perception Technique for an Autonomous Robot System

Authors
Pinto, AM; Moreira, AP; Correia, MV; Costa, PG;

Publication
JOURNAL OF INTELLIGENT & ROBOTIC SYSTEMS

Abstract
Visual motion perception from a moving observer is the most often encountered case in real life situations. It is a complex and challenging problem, although, it can promote the arising of new applications. This article presents an innovative and autonomous robotic system designed for active surveillance and a dense optical flow technique. Several optical flow techniques have been proposed for motion perception however, most of them are too computationally demanding for autonomous mobile systems. The proposed HybridTree method is able to identify the intrinsic nature of the motion by performing two consecutive operations: expectation and sensing. Descriptive properties of the image are retrieved using a tree-based scheme and during the expectation phase. In the sensing operation, the properties of image regions are used by a hybrid and hierarchical optical flow structure to estimate the flow field. The experiments prove that the proposed method extracts reliable visual motion information in a short period of time and is more suitable for applications that do not have specialized computer devices. Therefore, the HybridTree differs from other techniques since it introduces a new perspective for the motion perception computation: high level information about the image sequence is integrated into the estimation of the optical flow. In addition, it meets most of the robotic or surveillance demands and the resulting flow field is less computationally demanding comparatively to other state-of-the-art methods.

2014

Enhancing dynamic videos for surveillance and robotic applications: The robust bilateral and temporal filter

Authors
Pinto, AM; Costa, PG; Correia, MV; Moreira, AP;

Publication
SIGNAL PROCESSING-IMAGE COMMUNICATION

Abstract
Over the last few decades, surveillance applications have been an extremely useful tool to prevent dangerous situations and to identify abnormal activities. Although, the majority of surveillance videos are often subjected to different noises that corrupt structured patterns and fine edges. This makes the image processing methods even more difficult, for instance, object detection, motion segmentation, tracking, identification and recognition of humans. This paper proposes a novel filtering technique named robust bilateral and temporal (RBLT), which resorts to a spatial and temporal evolution of sequences to conduct the filtering process while preserving relevant image information. A pixel value is estimated using a robust combination of spatial characteristics of the pixel's neighborhood and its own temporal evolution. Thus, robust statics concepts and temporal correlation between consecutive images are incorporated together which results in a reliable and configurable filter formulation that makes it possible to reconstruct highly dynamic and degraded image sequences. The filtering is evaluated using qualitative judgments and several assessment metrics, for different Gaussian and Salt Pepper noise conditions. Extensive experiments considering videos obtained by stationary and non-stationary cameras prove that the proposed technique achieves a good perceptual quality of filtering sequences corrupted with a strong noise component.

2013

Fast 3D Map Matching Localisation Algorithm

Authors
Pinto, M; Moreira, AP; Matos, A; Sobreira, H; Santos, F;

Publication
Journal of Automation and Control Engineering - JOACE

Abstract

2013

Humanoid Gait Optimization Resorting to an Improved Simulation Model

Authors
Lima, JL; Goncalves, JA; Costa, PG; Moreira, AP;

Publication
INTERNATIONAL JOURNAL OF ADVANCED ROBOTIC SYSTEMS

Abstract
The simulation of a robot with a high number of joints can easily become unstable. Numerical errors on the first joint of the chain are propagated to the other joints. This is a very common problem in humanoid robots. A way to plan the gait for these robots is using simulation and optimization techniques. This paper addresses a new approach to optimizing gait parameter sets using an adaptive simulated annealing optimization algorithm, combined with a new joint model that reduces its instability. The new model and the optimization are implemented in SimTwo (a developed physical robot simulator that is capable of simulating user defined robots in a three-dimensional space, since it includes a physical model based on rigid body dynamics) and results are shown that validate the approach.

2014

Increasing Flexibility in Footwear Industrial Cells

Authors
Rocha, LF; Veiga, G; Ferreira, M; Paulo Moreira, AP; Santos, V;

Publication
2014 IEEE INTERNATIONAL CONFERENCE ON AUTONOMOUS ROBOT SYSTEMS AND COMPETITIONS (ICARSC)

Abstract
Nowadays, entering in the highly competitive international market becomes a key strategy for the survive and sustained growth of enterprises in the Portuguese textile and footwear industrial sector. Thereby, to face new requirements, companies need to understand that technological innovation is a key issue. In this scenario, the research presented in this paper focuses on the development of a robot based conveyor line pick-and-place solution to perform an automatic collection of the shoe last. The solution developed consists of extracting the 3D model of the shoe last suport transported in the conveyor line and aligning it, using the Iterative Closest Point (ICP) algorithm, with a template model previously recorded. The Camera-Laser triangulation system was the approach selected to extract the 3D model. With the correct position and orientation estimation of the conveyor footwear, it will make possible to execute the pick-and-place task using an industrial manipulator. The practical implication of this work is that it contributes to improve the footwear production lines efficiency, in order to meet demands in shorter periods of time, and with high quality standards. This work was developed in partnership with the Portuguese company CEI by ZIPOR.

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