Throughput Optimization In Robotic Cells provides practitioners, researchers, and students with up-to-date algorithmic results on sequencing of robot moves and scheduling of parts in robotic cells. It brings together the structural results developed over the last 25 years for the various realistic models of robotic cells. This book is ideally suited for use in a graduate course or a research seminar on robotic cells.

We consider the problem of scheduling operations in a robotic cell processing a single part type. Each machine in the cell has a one-unit input buffer and a one-unit output buffer. The machines and buffers are served by one single gripper robot. The domain considered is free-pickup cells with additive intermachine travel time. The processing constraints specify the cell to be a flow shop. The objective is to find a cyclic sequence of robot moves that minimizes the long-run average time to produce a part or, equivalently, maximizes throughput. Bufferless robotic cells have been studied extensively in the literature. However, the few studies of robotic cells with output buffers at each machine have shown that the throughput can be improved by such a configuration. We show that there is no throughput advantage in providing machine input buffers in addition to output buffers. The equivalence in throughput between the two models has significant practical implications, since the cost of providing additional buffers at each machine is substantial.

Constant travel-time robotic cells with a single gripper robot and with one or more machines at each processing stage have been studied in the literature. By contrast, cells with a dual gripper robot, although more productive, have so far received scant attention, perhaps due to their inherent complexity. We consider the problem of scheduling operations in dual gripper robotic cells that produce identical parts. The objective is to find a cyclic sequence of robot moves that minimizes the long-run average time to produce a part or, equivalently, maximizes the throughput. We provide a structural analysis of cells with one or more machines per processing stage to obtain first a lower bound on the throughput, and subsequently, an optimal solution under conditions that are common in practice. We illustrate our analysis on two cells implemented at a semiconductor equipment manufacturer and offer managerial insights for assessing the potential productivity gains from the use of dual gripper robots.

Interval robotic cells with several processing stages (chambers) have been increasingly used for diverse wafer fabrication processes in semi-conductor manufacturing. Processes such as low-pressure chemical vapor deposition, etching, cleaning and chemical-mechanical planarization, require strict time control for each processing stage. A wafer treated in a processing chamber must leave that chamber within a specified time limit; otherwise the wafer is exposed to residual gases and heat, resulting in quality problems. Interval robotic cells are also widely used in the manufacture of printed circuit boards. The problem of scheduling operations in dual-gripper interval robotic cells that produce identical wafers (or parts) is considered in this paper. The objective is to find a 1-unit cyclic sequence of robot moves that minimizes the long-run average time to produce a part or, equivalently, maximizes the throughput. Initially two extreme cases are considered, namely no-wait cells and free-pickup cells; for no-wait cells (resp., free-pickup cells), an optimal (resp., asymptotically optimal) solution is obtained in polynomial time. It is then proved that the problem is strongly NP-hard for a general interval cell. Finally, results of an extensive computational study aimed at analyzing the improvement in throughput realized by using a dual-gripper robot instead of a single-gripper robot are presented. It is shown that employing a dual-gripper robot can lead to a significant gain in productivity. Operations managers can compare the resulting increase in revenue with the additional costs of acquiring and maintaining a dual-gripper robot to determine the circumstances under which such an investment is appropriate.

We consider the problem of scheduling operations in bufferless robotic cells that produce identical parts. The objective is to find a cyclic sequence of robot moves that minimizes the long-run average time to produce a part or, equivalently, maximizes the throughput rate. The robot can be moved in simple cycles that produce one unit or, in more complicated cycles, that produce multiple units. Because one-unit cycles are the easiest to understand, implement, and control, they are widely used in industry. We analyze one-unit cycles for a class of robotic cells called constant travel-time robotic cells. We complete a structural analysis of the class of one-unit cycles and obtain a polynomial time algorithm for finding an optimal one-unit cycle. Constant travel-time robotic cells are used in real manufacturing operations that the authors have encountered during their interactions with companies. The results and the analysis in this paper offer practitioners (i) a tool to experiment with and study the design of a proposed robotic cell during a prototyping exercise, (ii) a lower bound on the throughput of a robotic cell to help them make an informed assessment of the ultimate productivity level, and (iii) a benchmark throughput level (for comparison purposes) for robotic cells whose operations differ slightly from those discussed in this paper.

Various systems science and engineering disciplines are covered and challenging new research issues in these disciplines are revealed. They will be extremely valuable for the readers to search for some new research directions and problems. Chapters are contributed by world-renowned systems engineers Chapters include discussions and conclusions Readers can grasp each event holistically without having professional expertise in the field

Striking a balance between state-of-the-art research and practical applications, this book provides a forum for contributions that cover the main research challenges in the cyclic modeling, development, and validation of concurrently acting distributed production systems: systems that employ multi-assortment production in large quantities, are characterized by gradual changes in their product mix, and exclusively manufacture products in a cyclic manner. Similar issues also arise in computer systems, e.g., embedded systems. Cyclic optimization problems that occur in them are unique and under-researched, but are attracting new interest primarily due to their great practical importance and the difficulty involved in obtaining efficient algorithms for solving specific cases with real constraints arising from manufacturing practice. Addressing these and other topics, the book will be of great interest to researchers in computer science, operations management, and production control, as well as practicing managers and engineers.

Managers are often under great pressure to improve the performance of their organizations. To improve performance, one needs to constantly evaluate operations or processes related to producing products, providing services, and marketing and selling products. Performance evaluation and benchmarking are a widely used method to identify and adopt best practices as a means to improve performance and increase productivity, and are particularly valuable when no objective or engineered standard is available to define efficient and effective performance. For this reason, benchmarking is often used in managing service operations, because service standards (benchmarks) are more difficult to define than manufacturing standards. Benchmarks can be established but they are somewhat limited as they work with single measurements one at a time. It is difficult to evaluate an organization’s performance when there are multiple inputs and outputs to the system. The difficulties are further enhanced when the relationships between the inputs and the outputs are complex and involve unknown tradeoffs. It is critical to show benchmarks where multiple measurements exist. The current book introduces the methodology of data envelopment analysis (DEA) and its uses in performance evaluation and benchmarking under the context of multiple performance measures.

This edited volume contains 16 research articles. It presents recent and pressing issues in stochastic processes, control theory, differential games, optimization, and their applications in finance, manufacturing, queueing networks, and climate control. One of the salient features is that the book is highly multi-disciplinary. The book is dedicated to Professor Suresh Sethi on the occasion of his 60th birthday, in view of his distinguished career.

This two volume set LNAI 8917 and 8918 constitutes the refereed proceedings of the 7th International Conference on Intelligent Robotics and Applications, ICIRA 2014, held in Guangzhou, China, in December 2014. The 109 revised full papers presented were carefully reviewed and selected from 159 submissions. The papers aim at enhancing the sharing of individual experiences and expertise in intelligent robotics with particular emphasis on technical challenges associated with varied applications such as biomedical applications, industrial automations, surveillance, and sustainable mobility.