An overview of hybrid simulation phenomena and their support by simulation packages

Continuous system dynamics can be described by, possibly large, systems of differential equations. These can be either ordinary differential equations (ODEs) or contain algebraic constraints as well to form differential and algebraic equations (DAEs). Complex systems, such as aircraft, often operate in different modes of continuous operation and when mode changes occur, the continuous dynamics change abruptly. Even small physical components may operate in different modes, e.g., a diode can operate as a short or open circuit, requiring abrupt discrete changes in the system of equations. Hybrid systems combine the continuous behavior evolution specified by differential equations with discontinuous changes specified by discrete event switching logic. Numerical simulation of continuous behavior and of discrete behavior is well understood. However, to facilitate simulation of mixed continuous/discrete systems a number of specific hybrid simulation issues must be addressed. This paper presents an overview o