Browsing by Author "Lau, Nuno"
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- Adapted control methods for cerebral palsy users of an intelligent wheelchairPublication . Faria, Brigida Monica; Reis, Luis Paulo; Lau, NunoThe development of an intelligent wheelchair (IW) platform that may be easily adapted to any commercial electric powered wheelchair and aid any person with special mobility needs is the main objective of this project. To be able to achieve this main objective, three distinct control methods were implemented in the IW: manual, shared and automatic. Several algorithms were developed for each of these control methods. This paper presents three of the most significant of those algorithms with emphasis on the shared control method. Experiments were performed by users suffering from cerebral palsy, using a realistic simulator, in order to validate the approach. The experiments revealed the importance of using shared (aided) controls for users with severe disabilities. The patients still felt having complete control over the wheelchair movement when using a shared control at a 50% level and thus this control type was very well accepted. Thus it may be used in intelligent wheelchairs since it is able to correct the direction in case of involuntary movements of the user but still gives him a sense of complete control over the IW movement.
- Cerebral Palsy EEG Signals Classification: Facial Expressions and Thoughts for Driving an Intelligent WheelchairPublication . Faria, Brígida Mónica; Reis, Luís Paulo; Lau, NunoBrain Computer Interfaces (BCI) enables interaction between users and hardware systems, through the recognition of brainwave activity. However, the current BCI systems still have a very low accuracy on the recognition of facial expressions and thoughts. This makes it very difficult to use these devices to enable safe and robust commands of complex devices such as an Intelligent Wheelchair. This paper presents an approach to expand the use of a brain computer interface for driving an intelligent wheelchair by patients suffering from cerebral palsy. The approach was based on appropriate signal preprocessing based on Hjorth parameters, a forward approach for variable selection and several data mining algorithms for classification such as naive Bayes, neural networks and support vector machines. Experiments were performed using 30 individuals suffering from IV and V degrees of cerebral palsy on the Gross Motor Function (GMF) measure. The results achieved showed that the preprocessing and variable selection methods were effective enabling to improve the results of a commercial BCI product by 57%. With the developed system it was also possible for users to perform a circuit in a simulated environment using just facial expressions and thoughts.
- Data visualization for analyzing simulated robotic soccer gamesPublication . Faria, Brigida Monica; Santos, Beatriz Sousa; Lau, Nuno; Reis, Luis PauloRoboCup is an international cooperative research project aimed at promoting research in Artificial Intelligence and Robotics. It includes a simulation league where two teams of 11 players compete in a robotic soccer game very similar to real soccer. Teams exhibit very complex strategies in these games that are very difficult to analyze by conventional observation methods. This paper presents an approach to the visualization of simulated robotic soccer games using the RapidMiner software package. Various visualizations were developed using Andrew´s Curves, Survey Plots, several types of Parallel Coordinate visualizations and Radial Coordinate Visualizations. These visualizations enabled to take some interesting conclusions about the differences between games of FC Portugal robotic soccer team using different formations and against distinct opponents.
- Evaluation of distinct input methods of an intelligent wheelchair in simulated and real environments: a performance and usability studyPublication . Faria, Brigida Monica; Vasconcelos, Sérgio; Reis, Luís Paulo; Lau, NunoThis paper focuses on evaluating the usability of an Intelligent Wheelchair (IW) in both real and simulated environments. The wheelchair is controlled at a high-level by a flexible multimodal interface, using voice commands, facial expressions, head movements and joystick as its main inputs. A Quasi-experimental design was applied including a deterministic sample with a questionnaire that enabled to apply the System Usability Scale. The subjects were divided in two independent samples: 46 individuals performing the experiment with an Intelligent Wheelchair in a simulated environment (28 using different commands in a sequential way and 18 with the liberty to choose the command); 12 individuals performing the experiment with a real IW. The main conclusion achieved by this study is that the usability of the Intelligent Wheelchair in a real environment is higher than in the simulated environment. However there were not statistical evidences to affirm that there are differences between the real and simulated wheelchairs in terms of safety and control. Also, most of users considered the multimodal way of driving the wheelchair very practical and satisfactory. Thus, it may be concluded that the multimodal interfaces enables very easy and safe control of the IW both in simulated and real environments.
- Intelligent wheelchair driving: a comparative study of cerebral palsy adults with distinct boccia experiencePublication . Faria, Brígida Mónica; Silva, Ana; Faias, Joaquim; Reis, Luís Paulo; Lau, NunoAn electronic wheelchair facilitates the autonomy and independence of a person, however specific cognitive, sensorial and perceptual skills are needed to conduct the assistive technology. These skills are also inherent to the sport boccia. Thus, the aim of this study is to understand the relationship between the experience of the participant in driving a wheelchair in relation to their autonomy and independence and also examine the practice of boccia in relation to the cognitive skills and performance in driving an intelligent wheelchair using a simulator. It was performed an evaluation of 28 participants, 6 of whom had no experience driving an electronic wheelchair and 22 had experience, 15 practice boccia and 13 did not practice this type of adapted sports. In the collection of data was tested three interfaces command of a smart wheelchair in a simulator. It was showed a good performance of the participants with experience in using electronic wheelchair and practitioners of boccia. It was also possible to observe that the autonomous and independent participants showed good results.
- Intelligent wheelchair driving: bridging the gap between virtual and real intelligent wheelchairsPublication . Faria, Brígida Mónica; Reis, Luís Paulo; Lau, Nuno; Moreira, António Paulo; Petry, Marcelo; Ferreira, Luís MiguelWheelchairs are important locomotion devices for handicapped and senior people. With the increase in the number of senior citizens and the increment of people bearing physical deficiencies, there is a growing demand for safer and more comfortable wheelchairs. So the new Intelligent Wheelchair (IW) concept was introduced. Like many other robotic systems, the main capabilities of an intelligent wheelchair should be: autonomous navigation with safety, flexibility and capability of avoiding obstacles; intelligent interface with the user; communication with other devices. In order to achieve these capabilities a good testbed is needed on which trials and users’ training may be safely conducted. This paper presents an extensible virtual environment simulator of an intelligent wheelchair to fulfill that purpose. The simulator combines the main features of robotic simulators with those built for training and evaluation of prospective wheelchair users. Experiments with the real prototype allowed having results and information to model the virtual intelligent wheelchair. Several experiments with real users of electric wheelchairs (suffering from cerebral palsy) and potential users of an intelligent wheelchair were performed. The System Usability Score allowed having the perception of the users in terms of the usability of the IW in the virtual environment. The mean score was 72 indicating a satisfactory level of the usability. It was possible to conclude with the experiments that the virtual intelligent wheelchair and environment are usable instruments to test and train potential users.
- Intelligent Wheelchair Manual Control MethodsPublication . Faria, Brígida Mónica; Ferreira, Luís Miguel; Reis, Luís Paulo; Lau, Nuno; Petry, MarceloAssistive 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.
- Intelligent wheelchair simulator for users' training: Cerebral palsy children's case studyPublication . Faria, Brigida Monica; Reis, Luis Paulo; Teixeira, Sofia Carmo; Faias, Joaquim; Lau, NunoThe use of real context simulation programs for training driving skills to control an intelligent wheelchair is an emergent area. The aim of this study is to verify if the exigency of use of the simulator of the IntellWheels project is adequate to the skills of children with cerebral palsy. A group study case was performed using children with cerebral palsy classified in the levels IV and V of the Gross Motor Function Classification System, aged between 6 and 12 years old. The user's performance in a wheelchair driving game using the Joystick and the Wiimote (for head movements' recognition) and the users' opinions about the system were studied. Results suggest that the system matches the children skills and it was verified that it was easier to drive the wheelchair with the joystick for most of the participants. Generally, the participants presented positive reactions, showing themselves satisfied with the experiment and convicted about the wheelchair future usability.
- Invited paper: multimodal interface for an intelligent wheelchairPublication . Reis, Luís Paulo; Faria, Brigida Monica; Vasconcelos, Sérgio; Lau, NunoSince the demographics of population, with respect to age, are continuously changing, politicians and scientists start to pay more attention to the needs of senior individuals. Additionally, the well-being and needs of disabled individuals are also becoming highly valued in the political and entrepreneurial society. Intelligent wheelchairs are adapted electric wheelchairs with environmental perception, semi-autonomous behaviour and flexible human-machine-interaction. This paper presents the specification and development of a user-friendly multimodal interface, as a component of the IntellWheels Platform project. The developed prototype combines several input modules, allowing the control of the wheelchair through flexible user defined input sequences of distinct types (speech, facial expressions, head movements and joystick). To validate the effectiveness of the prototype, two experiments were performed with a number of individuals who tested the system firstly by driving a simulated wheelchair in a virtual environment. The second experiment was performed using the real IntellWheels wheelchair prototype. The results achieved proved that the multimodal interface may be successfully used by people, due to the interaction flexibility it provides.
- Knowledge discovery and multimodal inputs for driving an intelligent wheelchairPublication . Faria, Brígida Mónica; Reis, Luís Paulo; Lau, NunoCerebral Palsy is defined as a group of permanent disorders in the development of movement and posture. The motor disorders in cerebral palsy are associated with deficits of perception, cognition, communication, and behaviour, which can affect autonomy and independence. The interface between the user and an intelligent wheelchair can be done with several input devices such as joysticks, microphones, and brain computer interfaces (BCI). BCI enables interaction between users and hardware systems through the recognition of brainwave activity. The current BCI systems have very low accuracy on the recognition of facial expressions and thoughts, making it difficult to use these devices to enable safe and robust commands of complex devices like an Intelligent Wheelchair. This paper presents an approach to expand the use of a brain computer interface for driving an intelligent wheelchair by patients suffering from cerebral palsy. The ability with the joystick, head movements, and voice inputs were tested, and the best possibility for driving the wheelchair is given to a specific user. Experiments were performed using 30 individuals suffering from IV and V degrees of cerebral palsy on the Gross Motor Function (GMF) measure. The results show that the pre-processing and variable selection methods are effective to improve the results of a commercial BCI product by 57%. With the developed system, it is also possible for users to perform a circuit in a simulated environment using just facial expressions and thoughts.