Evaluation of distinct input methods of an intelligent wheelchair in simulated and real environments: a performance and usability study

This 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.

Adapted Control Methods for Cerebral Palsy Users of an Intelligent Wheelchair

The 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.

A Methodology for Creating an Adapted Command Language for Driving an Intelligent Wheelchair

Intelligent wheelchairs (IW) are technologies that can increase the autonomy and independence of elderly people and patients suffering from some kind of disability. Nowadays the intelligent wheelchairs and the human-machine studies are very active research areas. This paper presents a methodology and a Data Analysis System (DAS) that provides an adapted command language to an user of the IW. This command language is a set of input sequences that can be created using inputs from an input device or a combination of the inputs available in a multimodal interface. The results show that there are statistical evidences to affirm that the mean of the evaluation of the DAS generated command language is higher than the mean of the evaluation of the command language recommended by the health specialist (p value = 0.002) with a sample of 11 cerebral palsy users. This work demonstrates that it is possible to adapt an intelligent wheelchair interface to the user even when the users present heterogeneous and severe physical constraints.

ezGo: A voice operated wheelchair with biosignal monitoring for home environments

In this paper we present ezGo, an electric powered wheelchair with a speech based interface and biosignal monitoring instrumentation. The user can use the voice, a natural communication method, for controlling the chair movement and obtain information about his health. Additionally a set of semi-autonomous modes with macro recording enable the execution of navigation tasks with little effort and improved precision. The main purpose of the system is to provide severely disabled persons with an assistive device that can improve their confidence and daily independence. The obtained results on usability tests showed that users consider ezGo a valuable help on their daily tasks and a very desirable addition to standard wheelchairs.

Unidade de interação e controlo para uma cadeira de rodas elétrica automática

Num mundo onde cerca de 1% da população necessita de utilizar uma cadeira de rodas para a sua deslocação, a acessibilidade a este tipo de veículo no exterior ainda encontra-se num estado bastante precário. Falta de rampas nos passeios, buracos, caminhos em declive e determinados obstáculos como carros estacionados por cima do passeio, são alguns de muitos exemplos dos desafios que uma pessoa em cadeira de rodas enfrenta quando tenta deslocar-se no exterior, o que faz com que a autonomia e a segurança na condução de uma cadeira de rodas seja bastante reduzida, sendo por muitas vezes necessário recorrer de forma constante à ajuda de terceiros, que, por consequência, reduz a sua, já limitada, liberdade de locomoção. É com base nestes problemas que o projeto RevoChair surgiu. Este projeto consiste no desenvolvimento de um sistema para cadeira de rodas elétrica que permita ao utilizador movimentar-se no exterior automaticamente, sempre que possível, sem ter de se preocupar com os obstáculos a sua volta. Esta tese incide-se concretamente sobre três dos problemas do desenvolvimento deste projeto, a definição das componentes necessárias para a implementação do sistema, a forma como o utilizador interage com o sistema e a forma como os componentes comunicam entre si, tendo como foco a unidade de interação e a unidade de controlo responsável por gerir a comunicação entre os diversos componentes do sistema.