Reliability of remote manipulator systems for use in radiation environments

The Commission of the European Communities runs a research programme called TELEMAN with the objective to develop advanced teleoperators (robots) that can operate in hazardous or disordered nuclear environments. The TELEMAN programme commenced in July 1989 and will continue beyond 1995 with a total funding of 19 million ECU. In the first phase, the programme had 16 projects, each covering a part of the development of components and subsystems. By the end of 1992 a second phase of the programme started, comprising five projects in which test machines were built, based on the knowledge gained in the phase-1 projects. The work described in the present paper has been performed as part of a phase-2 project called INGRID (Intelligent Nuclear Gantry Robot Integrated Demonstrator). The robots aimed at in TELEMAN will be more or less autonomous, meaning that they will be performing their tasks without continuous control by an operator. Taking into consideration the hostile environments foreseen, it must be aimed at that the robot does not break down totally during the work, since recovery of a stranded machine may be dangerous and difficult, if not impossible. Therefore, the reliability of the machine must be high and failure strategies must be established in order to ensure, that the robot returns to a safe state and location if faults, nevertheless, occur