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Introduction A (discrete part) manufacturing process, whether it be machining or assembly, consists of a sequence of steps that must occur to transform the raw materials into finished parts. A manufacturing system is a set of machines (and humans) along with associated control and information | 3 Discrete Event Control of Manufacturing Systems D. M. Tilbury University of Michigan P. P. Khargonekar University of Florida 3.1 Introduction 3.1 Introduction 3.2 Background on the Logic Control Problems Logic Control Definition Control Modes Logic Control Specification Tasks of a Logic Control Programmer 3.3 Current Industrial Practice Programmable Logic Controllers Relay Ladder Logic Sequential Function Charts 3.4 Current Trends Issues with Current Practice PC-Based Control Distributed Control Simulation 3.5 Formal Methods for Logic Control Important Criteria for Control Discrete Event Systems Finite State Machines Petri Nets 3.6 Further Reading A discrete part manufacturing process whether it be machining or assembly consists of a sequence of steps that must occur to transform the raw materials into finished parts. A manufacturing system is a set of machines and humans along with associated control and information systems protocols that implement the manufacturing process. The steps in the process often called operations are assigned to certain machines. The machines are arranged in a line and as the part moves along the line the specified operations are performed on it at the end of the line it becomes a finished product. The line of machines may be a physical arrangement or a virtual line where the machines are grouped into cells and an operator or computer guides the parts through the appropriate sequence of machines. Automated manufacturing systems must perform the same sequence of operations repeatedly. There are two distinct types of control systems in a typical automated manufacturing system continuous control and discrete event control. Continuous control systems regulate continuous variables such as position velocity etc. Discrete event control correctly sequences the system In current technology continuous control is often implemented using digital computers. In this sense this type of control is discrete-time digital control. This discrete-time .