Experiences Developing Safe and Fault-Tolerant Tele-Operated Service Robots. A Case Study in Shipyards

摘要

Human operators use tele-operated service robots for performing more or less hazardous operations (manipulation of heavy and/or dangerous products) in more or less hostile environments (nuclear reactors, space missions, warehouses, etc). Anyway, independently of the operation, the robot has to interact with both the environment it is working on and with human operators. Therefore, it is essential that the design (which include both software and hardware) of the robot involves no risk, or at least an acceptable level of risk, neither for the operators, nor for the environment nor for the robot itself. Nevertheless, it is not always possible to make a system free of failures in its design or operation. Apart from the risk inherent to the use of the mechanisms themselves, these systems work in hazardous environments, where the probability of the risk is higher than normal. Should a failure happen, its consequences could even involve the loss of human lives. Nevertheless, safety aspects are seldom included in the early phases of the system design process from the beginning, even though they are a critic aspect. Generally, safety has to conform and adapt to the already designed system and not vice versa, when it is widely known that safety involves not only the design of the software but also the hardware. Even more, a simple hardware solution can eliminate a hazard or simplify the software design in many situations. However, the identification of safety requirements should not be different from the identification of the rest of requirements of the system. It only requires a more thorough study due to their importance (human lives and equipment integrity may depend on it). On the other hand, safety has a big repercussion in both the specification and design phases, especially when the time to define the architecture of the system arrives. Its impact is even bigger by the need to avoid common failure modes, which can propagate failures within different units of the system. There are a number of standards and techniques for addressing safety requirements in electronic devices in general and for industrial arm robots, but none specifically designed www.intechopen.