ROBCHAIR - A SEMI-AUTONOMOUS WHEELCHAIR FOR DISABLED PEOPLE G. Pires, U. Nunes, A. T. de Almeida Institute of Systems and Robotics Department of Electrical Engineering University of Coimbra, Polo II 3030 Coimbra, Portugal email {gpires, urbano}@isr.uc.pt Abstract: This paper describes the RobChair assistive navigation system. RobChair is a project under development which aims to assist disabled people to operate powered wheelchairs. RobChair is being developed in order to provide several levels of functionality to assist different users. This paper describes some reactive navigational strategies, namely the potential field method, used for local obstacle avoidance; presents a teleoperation environment to allow remote operation by Internet observers; and introduces a voice human-machine interface (HMI). Keywords: behavioural architecture, obstacle avoidance, human-machine interface. 1. INTRODUCTION Unfortunately, “there is a significant growth in the absolute and relative number of older people in all Member States such that by the year 2020 it is estimated that one in four of the European population will be over 60 years of age” (Tide, 1994). This is a very alarming situation, since older people usually suffer from motor problems such as partial paralysis and tremors. There is also a great number of chronic physically handicapped people. Rehabilitation technology represents a major tool to overcome problems in daily life related with disability. The use of a wheelchair can, in many cases, integrate the disabled to have a normal social life. There are several kinds of disabilities which compels the wheelchair system to have different levels of functionality. For instance, a paraplegic person can, just as a normal person, use a joystick to control the wheelchair. However, a tetraplegic person has to use the tongue or the chin to operate a special joystick or has to use voice commands. In the first case, a wheelchair equipped with a normal joystick and a collision avoidance module (to provide a safe travel) would be enough. However, in the second case it would be desirable to have: a voice HMI (because controlling a joystick with the tongue or the chin is a very tedious and difficult task); a collision avoidance module; and, if possible, an autonomous navigation module. RobChair system is being developed with the following main purposes: guarantee the safety of wheelchair users; help users to perform some complex manoeuvres in cluttered environments; allow permanent communication between users and remote observers; provide an efficient HMI to guarantee that the wheelchair can be operated by users with different impairments; and finally, design a modular system with autonomous navigation capability. It is a concern of this project to design a wheelchair for the disabled and not a wheelchair for engineers. The organisation of the paper is as follows: section 2 describes the configuration system; section 3 presents the teleoperation environment; section 4 presents the navigational control architecture; section 5 introduces the voice HMI; section 6 presents some experimental