The Rehabilitation Robots FRIEND-I & II: Daily Life Independency through Semi-Autonomous Task-Execution

The rehabilitation robotic systems FRIEND1-I (Martens et al., 2001) and its successor FRIEND-II have been developing at the Institute of Automation (IAT), University of Bremen, Germany, since 1997 and 2003 respectively. The systems belong to the category “intelligent wheelchair mounted manipulators”. They focus on users with high spinal cord injury, or with similar handicaps, who are unable to control the manipulator by means of a keyboard or joystick. The systems offer support during daily life activities and at professional life. The strategic objective of the FRIEND as well as the succeeding AMaRob2 project, which focuses on the usage of FRIEND-II within the context of an intelligent environment, is to research into new methods to control the robotic system in such a way that their users become independent for at least 1.5 hours without support by nursing staff. Beside the aspect that this is one of the main requirements expressed by potential users, the fulfillment of this objective would have a strong impact on the commercialization of the rehabilitation robotic system itself. This article gives an overview of the FRIEND project and the robotic systems there from evolved. It is divided into a practical part, which presents the systems from a user oriented perspective, and into a theoretical part, which satisfies the system-engineer’s point of view. The user oriented part outlines the different development steps, functional improvements, hardware setups and lessons learned since 1997. Here, the facilities of the FRIEND-I system as well as a description of the innovations of the FRIEND-II system, currently under development, are described with specific emphasis of the AMaRob project. The reader becomes aware of the functionalities and services offered by the FRIEND rehabilitation robot and of the challenging technical complexity with which the development has to deal. The theoretical part is focused on the concept of semi-autonomous task-execution as a means of reasonable complexity reduction. Due to the consequent application of this concept a technically manageable robotic system emerges, which is able to execute tasks on a high level of abstraction in a reliable and robust manner. Within this context semi-autonomous task-