Modular finite state machines for logic control: Theory, verification and applications to reconfigurable manufacturing systems

Logic control is an integral part of manufacturing systems. The creation and debugging of the logic control represents a significant amount of the effort needed to design a large manufacturing system. Today's rapidly shifting markets have greatly reduced the life of a product design and the manufacturing system to produce it. As a result reconfigurable manufacturing systems are being developed which are capable of producing different parts over their lifetime.; These systems will need logic control which is capable of being easily reconfigured as the system changes. To enable this reconfiguration the logic control must be modular. To reduce the time to debug the original and reconfigured system, the logic control needs to be verifiable. This dissertation describes the development of a logic control framework, Modular Finite State Machines (MFSMs), for use in logic control for reconfigurable manufacturing systems. There are four major contributions presented in this dissertation.; The first contribution is the creation of MFSMs. MFSMs consist of a system of modules which interact by passing events. The logic within a module is represented as a Trigger/Response Finite State Machine (TR FSM). The allowed communication between modules is specified with interface TR FSMs called filters.; The second contribution is the creation of Trigger/Response (TR) Languages. TR languages are an extension of classical language theory to match the behavior of the composition of TR FSMs. The primary motivation for creating TR languages was to aid in constructing proofs about systems of TR FSMs.; The third contribution is the development of theoretical results for MFSMs. These results were generated with the help of TR languages. Significantly, the composition of TR FSMs was shown to be both commutative and associative, and a procedure for modularly verifying the absence of a certain class of errors was developed.; The fourth contribution is the demonstration of the practicality of MFSMs as a means of logic control for manufacturing systems. A set of software tools for manipulating, verifying and executing MFSMs was created. These tools were then used to successfully construct MFSM controllers for three manufacturing system testbeds.