The design of a wheelchair mounted robot

The purpose of a rehabilitation robot is to enable severely disabled people to reach, pick up and manipulate objects without the assistance of another person. Rehabilitation robots may be categorised in terms of the tasks that they are designed to perform. Some robots are designed to perform a specific task, e.g. to assist a person to feed themselves, or to perform a number of tasks quickly and repetitively, e.g. in the case of a vocational robot. Other robots are designed to perform general manipulation tasks. This paper begins with a brief international overview of commercially-marketed rehabilitation robots followed by a description of a robot workstation (the Wolfson robot) and a trolley-mounted robot (the Wessex robot), both of which were designed and built at the Bath Institute of Medical Engineering. The paper describes how, following the evaluation of the Wessex robot with tetraplegics, a project to design a wheelchair-mounted robot was conceived. The objective of this three-year project is to mount a manipulator similar to that designed for the Wessex robot on to a powered wheelchair. The project addresses the challenges associated with aesthetics, the user control interface, safety, wheelchair use and control, power requirements and the tasks that the user wishes to perform with the robot. Potential users have participated in the design process by completing questionnaires, giving personal interviews and evaluating a mock-up of a proposed design. The paper discusses the engineering solutions used in the design of the prototype and describes some of the compromises reached.