Disabled people assistance by a semiautonomous robotic system

E. Colle, M. Mallem, P. Hoppenot, S. Otmane
SCI'2000, to appear.

Abstract : The primary objective of rehabilitation robotics is to fully or partly restore the disabled userís manipulative function by placing a robot arm between the user and the environment. Different configurations of robot systems can be considered : i) table-mounted manipulator, ii) wheelchair-mounted arm, iii) autonomous or semi-autonomous mobile vehicle equipped with a manipulator.

Our assistance system is composed of a control-command station for the disabled person and a manipulator arm mounted on a mobile robot.The main constraints of such peculiar systems are flexibility to be adapted to each userís capabilities, modularity to make the system versatile, reliability and cost to be affordable. A good compromise between those constraints is reached by a semiautonomous system in which robotics give the system as autonomy as possible and man-machine co-operation palliates both the deficiencies of the person due to the handicap and the limits of the machine. The main objective is to do a service to the person with the principle the machine must not Ďdo forí but compensates the action deficiency of the disabled person. Besides the psychological aspect the person intervention has the advantage of simplifying the design of the machine. The person mainly brings perception and decision skills and machine, action capabilities.

The approach consists to determine the autonomy level reachable with an affordable machine using robotic solutions. Taking into account both the capabilities of the person and the robot, the man-machine co-operation defines the best task sharing to do the person a service such as "go and see" or " fetch and bring an object back". Task sharing must be dynamic to make the system adaptable to the userís specificities.

The man machine interface for the perception and the control of the semiautonomous robotic system is based on new remote control approaches: virtual reality or enhanced reality. Enhanced and virtual reality techniques aims at immersing the user into the site where the mission is in progress. The increasing interest of video game firms for the immersion idea contributes to reduce the cost of such technology. An important feature of the MMI is the use of virtual fixtures as perceptual overlays to enhance human operator performances during teleoperating a robot. Virtual fixtures improve accuracy and time for performing a task and may reduce both human operator mental processing and stress.