Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 2013
Most of the original image feature detectors are not able to cope with large photometric variatio... more Most of the original image feature detectors are not able to cope with large photometric variations, and their extensions that should improve detection eventually increase the computational cost and introduce more noise to the system. Here we extend the original SURF algorithm increasing its invariance to illumination changes. Our approach uses the local space average color descriptor as working space to detect invariant features. A theoretical analysis demonstrates the impact of distinct photometric variations on the response of blob-like features detected with the SURF algorithm. Experimental results demonstrate the effectiveness of the approach in several illumination conditions including the presence of two or more distinct light sources, variations in color, in offset and scale.
Nowadays, there are many technologies that support location systems involving intrusive and nonin... more Nowadays, there are many technologies that support location systems involving intrusive and nonintrusive equipment and also varying in terms of precision, range, and cost. However, the developers some time neglect the noise introduced by these systems, which prevents these systems from reaching their full potential. Focused on this problem, in this research work a comparison study between three different filters was performed in order to reduce the noise introduced by a location system based on RFID UWB technology with an associated error of approximately 18 cm. To achieve this goal, a set of experiments was devised and executed using a miniature train moving at constant velocity in a scenario with two distinct shapes-linear and oval. Also, this train was equipped with a varying number of active tags. The obtained results proved that the Kalman Filter achieved better results when compared to the other two filters. Also, this filter increases the performance of the location system by...
ABSTRACT Assistive Technologies may greatly contribute to give autonomy and independence for indi... more ABSTRACT Assistive Technologies may greatly contribute to give autonomy and independence for individuals with physical limitations. Electric wheelchairs are examples of those assistive technologies and nowadays each time becoming more intelligent due to the use of technology that provides assisted safer driving. Usually, the user controls the electric wheelchair with a conventional analog joystick. However, this implies the need for an appropriate methodology to map the position of the joystick handle, in a Cartesian coordinate system, to the wheelchair wheels intended velocities. This mapping is very important since it will determine the response behavior of the wheelchair to the user manual control. This paper describes the implementation of several joystick mappings in an intelligent wheelchair (IW) prototype. Experiments were performed in a realistic simulator using cerebral palsy users with distinct driving abilities. The users had 6 different joystick control mapping methods and for each user the usability and the users’ preference order was measured. The results achieved show that a linear mapping, with appropriate parameters, between the joystick’s coordinates and the wheelchair wheel speeds is preferred by the majority of the users.
2013 IEEE 15th International Conference on e-Health Networking, Applications and Services (Healthcom 2013), 2013
Intelligent wheelchairs can become an important solution to assist physically impaired individual... more Intelligent wheelchairs can become an important solution to assist physically impaired individuals who find it difficult or impossible to drive regular powered wheelchairs. However, when designing the hardware architecture several projects compromise the user comfort and the wheelchair normal usability in order to solve robotic problems. In this paper we describe the main concepts regarding the design of the IntellWheels intelligent wheelchair. Our approach has a user-centered perspective, in which the needs and limitations of physically impaired users are given extensive attention at each stage of the design process. Finally, our design was evaluated through a public opinion assessment. A statistical analysis suggested that the design was effective to mitigate the visual and ergonomic impacts caused by the addition of sensorial and processing capabilities on the wheelchair.
... [2] ALÉ, Jorge Antonio Villar; ADEGAS, Fabiano Daher; SIMIONI, Gabriel Cirilo; Methodologies... more ... [2] ALÉ, Jorge Antonio Villar; ADEGAS, Fabiano Daher; SIMIONI, Gabriel Cirilo; Methodologies for Power Curve Test of Small Wind Turbines. In: WINDPOWER 2005 Conference and Exhibition, Denver, USA. 2005. ... Marcelo R. Petry, Marcos VS Cattaneo Orientador: Prof. ...
1FEUP - Faculty of Engineering of the University of Porto, 2INESC-P Institute for Systems and Com... more 1FEUP - Faculty of Engineering of the University of Porto, 2INESC-P Institute for Systems and Computer Engineering of Porto, 3LIACC - Artificial Intelligence and Computer Science Lab. Rua Dr. Roberto Frias s/n, 4200-465, Porto, Portugal {marcelo.petry, rodrigo.braga, lpreis, amoreira}@fe.up.pt ... Real-time Obstacle Avoidance for Intelligent Wheelchairs ... DSIE'10 - Doctoral Symposium in Informatics Engineering 2 of 16 ... Real-Time Obstacle Avoidance for Intelligent Wheelchairs ... DSIE'10 - Doctoral Symposium in Informatics Engineering 3 of 16
In this paper we report on a methodology to model pedestrian behaviours whilst aggregate variable... more In this paper we report on a methodology to model pedestrian behaviours whilst aggregate variables are concerned, with potential applications to different situations, such as evacuating a building in emergency events. The approach consists of using UWB (ultra-wide band) based data collection to characterise behaviour in specific scenarios. From a number of experiments carried out, we detail the single-file scenario to demonstrate the ability of this approach to represent macroscopic characteristics of the pedestrian flow. Results are discussed and we can conclude that UWB-based data collection shows great potential and suitability for human trajectory extraction, when compared to other traditional approaches.
Page 1. http://www.fe.up.pt/~ext07047/ 1 NIAD&R – Distributed Artificial Intelligence and Robotic... more Page 1. http://www.fe.up.pt/~ext07047/ 1 NIAD&R – Distributed Artificial Intelligence and Robotics Group Discente: Marcelo Roberto Petry Orientador: Professor Doutor Luís Paulo Reis Co-orientador: Mestre Rodrigo Antônio Marques Braga Desenvolvimento de um Protótipo e de Metodologias de Controlo de uma Cadeira de Rodas Inteligente Page 2.
Abstract: The development of intelligent wheelchairs is a very good solution to assist severely h... more Abstract: The development of intelligent wheelchairs is a very good solution to assist severely handicapped people who are unable to operate classical electrical wheelchair by themselves in their daily activities. This paper describes the integration of a robotic simulator with our intelligent wheelchair shared control and planning modules. An adapted version of the free Cyber-Mouse robotic simulator was used to simulate the movement of the intelligent wheelchair in a hospital environment.
Resumo. O trabalho faz parte de um projeto FINEP no qual são desenvolvidos e testados diferentes ... more Resumo. O trabalho faz parte de um projeto FINEP no qual são desenvolvidos e testados diferentes modelos de turbinas eólicas de eixo vertical (TEEV). Estas máquinas apresentam características diferenciadas das turbinas eólicas de eixo horizontal (TEEH). São máquinas de maior solidez, rotação mais baixa, contudo apropriadas para uso urbano com ventos mais turbulentos.
Abstract Nowadays location systems are used within a large variety of applications. The applicati... more Abstract Nowadays location systems are used within a large variety of applications. The application of these systems within indoor environments is already provided by several solutions. However, the need for high accuracy within these environments to pursue such a purpose implies the use of specific infrastructures designed towards it. Our project tries to meet the requirements for a simple, low-cost, and scalable location system through different approaches.
In this paper we report on a methodology to model pedestrian behaviours whilst aggregate variable... more In this paper we report on a methodology to model pedestrian behaviours whilst aggregate variables are concerned, with potential applications to different situations, such as evacuating a building in emergency events. The approach consists of using UWB (ultrawide band) based data collection to characterise behaviour in specific scenarios. From a number of experiments carried out, we detail the single-file scenario to demonstrate the ability of this approach to represent macroscopic characteristics of the pedestrian flow. Results are discussed and we can conclude that UWB-based data collection shows great potential and suitability for human trajectory extraction, when compared to other traditional approaches.
Electric wheelchairs are now more intelligent due to the use of algorithms that provide assisted ... more Electric wheelchairs are now more intelligent due to the use of algorithms that provide assisted driving. Typically, the user steers the electric wheelchairs with conventional analog joysticks. This implies the need for an appropriate methodology to map the position of the joystick handle in a Cartesian coordinate system to the wheelchair motor velocities. This mapping of joystick positions to individual wheel speed can be done in an infinite number of combinations. However it is this mapping that will determine the response behavior of the wheelchair to the user manual control. This paper describes the implementation of several joystick mappings in an intelligent wheelchair prototype. Experiments were performed in a realistic simulator using 25 users with distinct driving abilities. The users had 6 different joystick control mapping methods and for each user the usability and preference order was measured. The results achieved enable to conclude that a more direct mapping between the joystick's coordinates and the wheelchair behavior is preferred by the majority of the users.
Intelligent wheelchairs operating in dynamic environments need to sense its neighborhood and adap... more Intelligent wheelchairs operating in dynamic environments need to sense its neighborhood and adapt the control signal, in real-time, to avoid collisions and protect the user. In this paper we propose a robust, real-time obstacle avoidance extension of the classic potential field methodology. Our algorithm is specially adapted to share the wheelchair’s control with the user avoiding risky situations. This method relies on the idea of virtual forces, generated by the user command (attractive force) and by the objects detected on each ultrasonic sensor (repulsive forces), acting on the wheelchair. The resultant wheelchair’s behavior is obtained by the sum of the attractive force and all the repulsive forces at a given position. Experimental results from drive tests in a cluttered office environment provided statistical evidence that the proposed algorithm is effective to reduce the number of collisions and still improve the user’s safety perception.
Nowadays location systems are used within a large variety of applications. The application of the... more Nowadays location systems are used within a large variety of applications. The application of these systems within indoor environments is already provided by several solutions. However, the need for high accuracy within these environments to pursue such purpose implies the use of specific infrastructures designed towards it. Our project tries to meet the requirements for a imple, low-cost, and scalable location system through different approaches. The main idea of it is to re-construct topological maps of indoor spaces through location estimation, i.e. using off-the-shelf technologies. We try to perform location estimations and then re-create the indoor maps as topological maps as a means of reducing the precision requirements other systems have, and develop a scalable and highly applicable system using sensors featuring mobile devices.
Intelligent wheelchairs (IWs) can become an important solution to the challenge of assisting indi... more Intelligent wheelchairs (IWs) can become an important solution to the challenge of assisting individuals who have disabilities and are thus unable to perform their daily activities using classic powered wheelchairs. This article describes the concept and design of IntellWheels, a modular platform to facilitate the development of IWs through a multiagent system paradigm. In fact, modularity is achieved not only in the software perspective, but also through a generic hardware framework that was designed to fit, in a straightforward manner, almost any commercial powered wheelchair. Experimental results demonstrate the successful integration of all modules in the platform, providing safe motion to the IW. Furthermore, the results achieved with a prototype running in autonomous mode in simulated and mixed-reality environments also demonstrate the potential of our approach. Although some future research is still necessary to fully accomplish our objectives, preliminary tests have shown that IntellWheels will effectively reduce users’ limitations, offering them a much more independent life.
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 2013
Most of the original image feature detectors are not able to cope with large photometric variatio... more Most of the original image feature detectors are not able to cope with large photometric variations, and their extensions that should improve detection eventually increase the computational cost and introduce more noise to the system. Here we extend the original SURF algorithm increasing its invariance to illumination changes. Our approach uses the local space average color descriptor as working space to detect invariant features. A theoretical analysis demonstrates the impact of distinct photometric variations on the response of blob-like features detected with the SURF algorithm. Experimental results demonstrate the effectiveness of the approach in several illumination conditions including the presence of two or more distinct light sources, variations in color, in offset and scale.
Nowadays, there are many technologies that support location systems involving intrusive and nonin... more Nowadays, there are many technologies that support location systems involving intrusive and nonintrusive equipment and also varying in terms of precision, range, and cost. However, the developers some time neglect the noise introduced by these systems, which prevents these systems from reaching their full potential. Focused on this problem, in this research work a comparison study between three different filters was performed in order to reduce the noise introduced by a location system based on RFID UWB technology with an associated error of approximately 18 cm. To achieve this goal, a set of experiments was devised and executed using a miniature train moving at constant velocity in a scenario with two distinct shapes-linear and oval. Also, this train was equipped with a varying number of active tags. The obtained results proved that the Kalman Filter achieved better results when compared to the other two filters. Also, this filter increases the performance of the location system by...
ABSTRACT Assistive Technologies may greatly contribute to give autonomy and independence for indi... more ABSTRACT Assistive Technologies may greatly contribute to give autonomy and independence for individuals with physical limitations. Electric wheelchairs are examples of those assistive technologies and nowadays each time becoming more intelligent due to the use of technology that provides assisted safer driving. Usually, the user controls the electric wheelchair with a conventional analog joystick. However, this implies the need for an appropriate methodology to map the position of the joystick handle, in a Cartesian coordinate system, to the wheelchair wheels intended velocities. This mapping is very important since it will determine the response behavior of the wheelchair to the user manual control. This paper describes the implementation of several joystick mappings in an intelligent wheelchair (IW) prototype. Experiments were performed in a realistic simulator using cerebral palsy users with distinct driving abilities. The users had 6 different joystick control mapping methods and for each user the usability and the users’ preference order was measured. The results achieved show that a linear mapping, with appropriate parameters, between the joystick’s coordinates and the wheelchair wheel speeds is preferred by the majority of the users.
2013 IEEE 15th International Conference on e-Health Networking, Applications and Services (Healthcom 2013), 2013
Intelligent wheelchairs can become an important solution to assist physically impaired individual... more Intelligent wheelchairs can become an important solution to assist physically impaired individuals who find it difficult or impossible to drive regular powered wheelchairs. However, when designing the hardware architecture several projects compromise the user comfort and the wheelchair normal usability in order to solve robotic problems. In this paper we describe the main concepts regarding the design of the IntellWheels intelligent wheelchair. Our approach has a user-centered perspective, in which the needs and limitations of physically impaired users are given extensive attention at each stage of the design process. Finally, our design was evaluated through a public opinion assessment. A statistical analysis suggested that the design was effective to mitigate the visual and ergonomic impacts caused by the addition of sensorial and processing capabilities on the wheelchair.
... [2] ALÉ, Jorge Antonio Villar; ADEGAS, Fabiano Daher; SIMIONI, Gabriel Cirilo; Methodologies... more ... [2] ALÉ, Jorge Antonio Villar; ADEGAS, Fabiano Daher; SIMIONI, Gabriel Cirilo; Methodologies for Power Curve Test of Small Wind Turbines. In: WINDPOWER 2005 Conference and Exhibition, Denver, USA. 2005. ... Marcelo R. Petry, Marcos VS Cattaneo Orientador: Prof. ...
1FEUP - Faculty of Engineering of the University of Porto, 2INESC-P Institute for Systems and Com... more 1FEUP - Faculty of Engineering of the University of Porto, 2INESC-P Institute for Systems and Computer Engineering of Porto, 3LIACC - Artificial Intelligence and Computer Science Lab. Rua Dr. Roberto Frias s/n, 4200-465, Porto, Portugal {marcelo.petry, rodrigo.braga, lpreis, amoreira}@fe.up.pt ... Real-time Obstacle Avoidance for Intelligent Wheelchairs ... DSIE'10 - Doctoral Symposium in Informatics Engineering 2 of 16 ... Real-Time Obstacle Avoidance for Intelligent Wheelchairs ... DSIE'10 - Doctoral Symposium in Informatics Engineering 3 of 16
In this paper we report on a methodology to model pedestrian behaviours whilst aggregate variable... more In this paper we report on a methodology to model pedestrian behaviours whilst aggregate variables are concerned, with potential applications to different situations, such as evacuating a building in emergency events. The approach consists of using UWB (ultra-wide band) based data collection to characterise behaviour in specific scenarios. From a number of experiments carried out, we detail the single-file scenario to demonstrate the ability of this approach to represent macroscopic characteristics of the pedestrian flow. Results are discussed and we can conclude that UWB-based data collection shows great potential and suitability for human trajectory extraction, when compared to other traditional approaches.
Page 1. http://www.fe.up.pt/~ext07047/ 1 NIAD&R – Distributed Artificial Intelligence and Robotic... more Page 1. http://www.fe.up.pt/~ext07047/ 1 NIAD&R – Distributed Artificial Intelligence and Robotics Group Discente: Marcelo Roberto Petry Orientador: Professor Doutor Luís Paulo Reis Co-orientador: Mestre Rodrigo Antônio Marques Braga Desenvolvimento de um Protótipo e de Metodologias de Controlo de uma Cadeira de Rodas Inteligente Page 2.
Abstract: The development of intelligent wheelchairs is a very good solution to assist severely h... more Abstract: The development of intelligent wheelchairs is a very good solution to assist severely handicapped people who are unable to operate classical electrical wheelchair by themselves in their daily activities. This paper describes the integration of a robotic simulator with our intelligent wheelchair shared control and planning modules. An adapted version of the free Cyber-Mouse robotic simulator was used to simulate the movement of the intelligent wheelchair in a hospital environment.
Resumo. O trabalho faz parte de um projeto FINEP no qual são desenvolvidos e testados diferentes ... more Resumo. O trabalho faz parte de um projeto FINEP no qual são desenvolvidos e testados diferentes modelos de turbinas eólicas de eixo vertical (TEEV). Estas máquinas apresentam características diferenciadas das turbinas eólicas de eixo horizontal (TEEH). São máquinas de maior solidez, rotação mais baixa, contudo apropriadas para uso urbano com ventos mais turbulentos.
Abstract Nowadays location systems are used within a large variety of applications. The applicati... more Abstract Nowadays location systems are used within a large variety of applications. The application of these systems within indoor environments is already provided by several solutions. However, the need for high accuracy within these environments to pursue such a purpose implies the use of specific infrastructures designed towards it. Our project tries to meet the requirements for a simple, low-cost, and scalable location system through different approaches.
In this paper we report on a methodology to model pedestrian behaviours whilst aggregate variable... more In this paper we report on a methodology to model pedestrian behaviours whilst aggregate variables are concerned, with potential applications to different situations, such as evacuating a building in emergency events. The approach consists of using UWB (ultrawide band) based data collection to characterise behaviour in specific scenarios. From a number of experiments carried out, we detail the single-file scenario to demonstrate the ability of this approach to represent macroscopic characteristics of the pedestrian flow. Results are discussed and we can conclude that UWB-based data collection shows great potential and suitability for human trajectory extraction, when compared to other traditional approaches.
Electric wheelchairs are now more intelligent due to the use of algorithms that provide assisted ... more Electric wheelchairs are now more intelligent due to the use of algorithms that provide assisted driving. Typically, the user steers the electric wheelchairs with conventional analog joysticks. This implies the need for an appropriate methodology to map the position of the joystick handle in a Cartesian coordinate system to the wheelchair motor velocities. This mapping of joystick positions to individual wheel speed can be done in an infinite number of combinations. However it is this mapping that will determine the response behavior of the wheelchair to the user manual control. This paper describes the implementation of several joystick mappings in an intelligent wheelchair prototype. Experiments were performed in a realistic simulator using 25 users with distinct driving abilities. The users had 6 different joystick control mapping methods and for each user the usability and preference order was measured. The results achieved enable to conclude that a more direct mapping between the joystick's coordinates and the wheelchair behavior is preferred by the majority of the users.
Intelligent wheelchairs operating in dynamic environments need to sense its neighborhood and adap... more Intelligent wheelchairs operating in dynamic environments need to sense its neighborhood and adapt the control signal, in real-time, to avoid collisions and protect the user. In this paper we propose a robust, real-time obstacle avoidance extension of the classic potential field methodology. Our algorithm is specially adapted to share the wheelchair’s control with the user avoiding risky situations. This method relies on the idea of virtual forces, generated by the user command (attractive force) and by the objects detected on each ultrasonic sensor (repulsive forces), acting on the wheelchair. The resultant wheelchair’s behavior is obtained by the sum of the attractive force and all the repulsive forces at a given position. Experimental results from drive tests in a cluttered office environment provided statistical evidence that the proposed algorithm is effective to reduce the number of collisions and still improve the user’s safety perception.
Nowadays location systems are used within a large variety of applications. The application of the... more Nowadays location systems are used within a large variety of applications. The application of these systems within indoor environments is already provided by several solutions. However, the need for high accuracy within these environments to pursue such purpose implies the use of specific infrastructures designed towards it. Our project tries to meet the requirements for a imple, low-cost, and scalable location system through different approaches. The main idea of it is to re-construct topological maps of indoor spaces through location estimation, i.e. using off-the-shelf technologies. We try to perform location estimations and then re-create the indoor maps as topological maps as a means of reducing the precision requirements other systems have, and develop a scalable and highly applicable system using sensors featuring mobile devices.
Intelligent wheelchairs (IWs) can become an important solution to the challenge of assisting indi... more Intelligent wheelchairs (IWs) can become an important solution to the challenge of assisting individuals who have disabilities and are thus unable to perform their daily activities using classic powered wheelchairs. This article describes the concept and design of IntellWheels, a modular platform to facilitate the development of IWs through a multiagent system paradigm. In fact, modularity is achieved not only in the software perspective, but also through a generic hardware framework that was designed to fit, in a straightforward manner, almost any commercial powered wheelchair. Experimental results demonstrate the successful integration of all modules in the platform, providing safe motion to the IW. Furthermore, the results achieved with a prototype running in autonomous mode in simulated and mixed-reality environments also demonstrate the potential of our approach. Although some future research is still necessary to fully accomplish our objectives, preliminary tests have shown that IntellWheels will effectively reduce users’ limitations, offering them a much more independent life.
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Papers by Marcelo Petry
towards it. Our project tries to meet the requirements for a imple, low-cost, and scalable location system through different approaches. The main idea of it is to re-construct topological maps of indoor spaces through location estimation, i.e. using off-the-shelf technologies. We try to perform location estimations and then re-create the indoor maps as topological maps as a means of reducing the precision requirements other systems have, and develop a scalable and highly applicable system using sensors featuring mobile devices.
towards it. Our project tries to meet the requirements for a imple, low-cost, and scalable location system through different approaches. The main idea of it is to re-construct topological maps of indoor spaces through location estimation, i.e. using off-the-shelf technologies. We try to perform location estimations and then re-create the indoor maps as topological maps as a means of reducing the precision requirements other systems have, and develop a scalable and highly applicable system using sensors featuring mobile devices.