A hazard control system for a robot in Space Shuttle applications

Abstract

Unlike the industrial robots in wide use around the world today, which generally perform various but limited repetitive tasks, the robot for space applications will be required to complete different types of tasks, including assembly, maintenance, and inspection tasks for Space Station Freedom. This fact, coupled with the harshness of the space environment, presents unusual and highly difficult challenges to ensuring the safety of astronauts and keeping the equipment they depend on from becoming damaged. The application of system safety engineering to the design and development of the robot ensures that it will not become an instrument of harm or destruction to the space vehicle and its occupants. This paper describes the systematic approach being taken to control hazards that could result from introducing robotics technology in the space environment. First, it will discuss system safety management and engineering principles, techniques, and requirements as they relate to Shuttle payload design and operation in general. The concepts of hazard, hazard category, and hazard control, as defined by the Shuttle payload safety requirements, will be explained.Second, this paper will show how these general safety management and engineering principles are being implemented on an actual project. It will present an example of a hazard control system scheme for controlling one of the hazards identified for the first test flight (Development Test Flight-1) of the Flight Telerobotic Servicer, a teleoperated space robot. System Safetv Engineering ConceptsSystem safety is the overall management and engineering approach to the evaluation and reduction of risk in a system and its operation. In general, system safety activities include systematic identification of hazards, elimination of those hazards to the maximum extent possible, assessment of the residual risk inherent in the system or its operation, management review and acceptance of the risk, and documentation of the management decision and rationale in accepting the risk. In addition, some type of control or controls for the hazards must be instituted.In order to analyze the safety of any system properly, the system safety engineer must have a thorough knowledge of the system, subsystems, interfaces, functions, characteristics, intended use or operation, and the operational environment. It is therefore necessary for the,system safety engineer to work closely with systems engineering, subsystem/component design engineering, mission operations, and support engineering personnel in developing a complete and accurate system description and operations scenario that can adequately support the identification of all potential hazards in the design and use of the system.