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Publications

Publications by CRAS

2016

An Optimization Approach for the Inverse Kinematics of a Highly Redundant Robot

Authors
Costa, P; Lima, J; Pereira, AI; Costa, P; Pinto, A;

Publication
PROCEEDINGS OF THE SECOND INTERNATIONAL AFRO-EUROPEAN CONFERENCE FOR INDUSTRIAL ADVANCEMENT (AECIA 2015)

Abstract
This paper describes a robot with 12 degrees of freedom for pick-and-place operations using bricks. In addition, an optimization approach is proposed, which determines the state of each joint (that establishes the pose for the robot) based on the target position while minimizing the effort of the servomotors avoiding the inverse kinematics problem, which is a hard task for a 12 DOF robot manipulator. Therefore, it is a multi-objective optimization problem that will be solved using two optimization methods: the Stretched Simulated Annealing method and the NSGA II method. The experiments conducted in a simulation environment prove that the proposed approach is able to determine a solution for the inverse kinematics problem. A real robot formed by several servomotors and a gripper is also presented in this research for validating the solutions.

2016

The SPIDERobot: A Cable-Robot System for On-site Construction in Architecture

Authors
Sousa, JP; Palop, CG; Moreira, E; Pinto, AM; Lima, J; Costa, P; Costa, P; Veiga, G; Paulo Moreira, A;

Publication
Robotic Fabrication in Architecture, Art and Design 2016

Abstract

2016

WirelessSyncroVision: Wireless synchronization for industrial stereoscopic systems

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

Publication
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY

Abstract
The research proposes a novel technological solution for marker-based human motion capture called WirelessSyncroVision (WSV). The WSV is formed by two main modules: the visual node (WSV-V) which is based on a stereoscopic vision system and the marker node (WSV-M) that is constituted by a 6-DOF active marker. The solution synchronizes the acquisition of images in remote muti-cameras with the ON period of the active marker. This increases the robustness of the stereoscopic system to illumination changes, which is extremely relevant for programming industrial robotic-arms using a human demonstrator programming by demonstration (PbD). In addition, the research presents a robust method named Adaptive and Robust Synchronization (ARS), that is designed for temporal alignment of remote devices using a wireless network. The algorithm models the phase difference as a function of time, measuring the parameters that must be known to predict the synchronization instant between the active marker and the remote cameras. Results demonstrate that the ARS creates a balance between the real-time capability and the performance estimation of the phase difference. Therefore, this research proposes an elegant solution to synchronize image acquisition systems in real-time that is easy to implement with low operational costs; however, the major advantage of the WSV is related to its high level of flexibility since it can be extended toward to other devices besides the PbD, for instance, motion capture, motion analysis, and remote sensoring systems.

2016

Motion Descriptor for Human Gesture Recognition in Low Resolution Images

Authors
Ferreira, A; Silva, G; Dias, A; Martins, A; Campilho, A;

Publication
ROBOT 2015: SECOND IBERIAN ROBOTICS CONFERENCE: ADVANCES IN ROBOTICS, VOL 1

Abstract
A great variety of human gesture recognition methods exist in the literature, yet there is still a lack of solutions to encompass some of the challenges imposed by real life scenarios. In this document, a gesture recognition for robotic search and rescue missions in the high seas is presented. Themethod aims to identify shipwrecked people by recognizing the hand waving gesture sign. We introduce a novelmotion descriptor, through which high recognition accuracy can be achieved even for low resolution images. The method can be simultaneously applied to rigid object characterization, hence object and gesture recognition can be performed simultaneously. The descriptor has a simple implementation and is invariant to scale and gesture speed. Tests, preformed on a maritime dataset of thermal images, proved the descriptor ability to reach a meaningful representation for very low resolution objects. Recognition rates with 96.3% of accuracy were achieved.

2016

ISEP/INESC TEC Aerial Robotics Team for Search and Rescue Operations at the EuRathlon Challenge 2015

Authors
Sousa, PM; Ferreira, A; Moreira, M; Santos, T; Martins, A; Dias, A; Almeida, JM; da Silva, EP;

Publication
2016 International Conference on Autonomous Robot Systems and Competitions, ICARSC 2016, Bragança, Portugal, May 4-6, 2016

Abstract

2016

LSA Portraiture Robot

Authors
Rodrigues, B; Cruz, E; Dias, A; Silva, MF;

Publication
ROBOT 2015: SECOND IBERIAN ROBOTICS CONFERENCE: ADVANCES IN ROBOTICS, VOL 2

Abstract
This paper describes the development of an application that allows an ABB robot arm to automatically perform the portrait of people. The Portraiture Robot performs the picture of a human face on paper. The developed system consists of 4 steps: (i) image acquisition through a webcam, (ii) image processing to retrieve the contours and features of the person's face, (iii) vectorization of the coordinates in the image plane, and (iv) conversion of the coordinates to the RAPID programming language. To get only the person's face, is performed a background subtraction and to obtain only the necessary information from the image are used filtering techniques to remove the features and contours of the person's face. To convert these points into x, y coordinates, the contours are vectorised and sent to a file, saved according to a defined protocol, and allowing to create a program for the robot. The developed application allows processing of all blocks listed above in real-time and in a robust manner, having the ability to adapt to any environment and allowing continued use. The work was validated through the participation in the 2014 Portuguese Robotics Open, and in an ISEP exhibition that occurred in Maia, always with good results.

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