Describing the design contributors to mode error

Although mode error has attracted a great deal of recent interest from those involved with complex systems, the design factors that contribute to this problems are not well understood. We provide an introduction to a modeling framework we use to describe complex, multi modal human machine systems. The modeling approach is based on the statechart formalism, which is an extension of the finite state machine formalism to allow representation of concurrency, hierarchy, default transitions, and broadcast of parameter information. After having used this approach to model a number of human machine systems known to create mode control problems for the operator, we have identified a number of system design features that contribute to mode error.