  Safety is now a major concern in many complex systems such as medical robots.
A way to control the complexity of such systems is to manage risk. The first
and important step of this activity is risk analysis. During risk analysis, two
main studies concerning human factors must be integrated: task analysis and
human error analysis. This multidisciplinary analysis often leads to a work
sharing between several stakeholders who use their own languages and
techniques. This often produces consistency errors and understanding
difficulties between them. Hence, this paper proposes to treat the risk
analysis on the common expression language UML (Unified Modeling Language) and
to handle human factors concepts for task analysis and human error analysis
based on the features of this language. The approach is applied to the
development of a medical robot for teleechography.
