Finite state machine application in open CNC

For improving reconfigurability in open architecture control system, Hierarchical Finite State Machine (HFSM) is applied to system behaviors' model which describes control logic of system. And modeling rules are given. In order to assure convenient implementation of FSM, a FSM foundation classes library is developed; it also provides interface to operate FSM. When behavioral modification due to system requirements change, mechanism for behavioral reconfiguration based on FSM is analyzed. Behavioral reconfiguration is demonstrated through integrating broken tool detection into an existing three-axis milling machine controller.