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Off-Line AGV Routing on the 2D Mesh Topology with Partial Permutation. Zeng Jianyang and Hsu Wen-Jing Center for Advanced Information Systems School of Computer Engineering Nanyang Technological University, Singapore 639798. Outline. Introduction Literature Review
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Off-Line AGV Routing on the 2D Mesh Topology with Partial Permutation Zeng Jianyang and Hsu Wen-Jing Center for Advanced Information Systems School of Computer Engineering Nanyang Technological University, Singapore 639798
Outline • Introduction • Literature Review • Off-Line Mesh Routing • Conclusions and Future Work 2 / 18
Outline • Introduction • Literature Review • Off-Line Mesh Routing • Conclusions and Future Work 3 / 18
Introduction • AGV: Automated Guided Vehicles • Problem of AGV Routing • Feasible or even optimal path • Simultaneously, without conflict, deadlock, and congestion • Compared with Shortest Path Problem (SPP) • SPP is simpler than AGV routing problem • Compared with Vehicle Routing Problem (VRP) • Length of vehicle is negligible in VRP • Collisions can be ignored in VRP • Topology is fixed and irregular in VRP 4 / 18
Outline • Introduction • Literature Review • Off-Line Mesh Routing • Conclusions and Future Work 5 / 18
Dijkstra’s alg, • 0-1 integer programming: • [Gaskins et al. 87] [Kaspi et al. 90] [Goetz et al. 90] • Small scale, simple, does not consider congestion, deadlocks Literature Review AGV routing for arbitrary topologies • Shortest path method • Time-window-based method • Dynamic method • [Huang et al. 89], [Fujii et al. 89], [Kim et al. 93] • Increased path utilization, expensive in computation, small system • [Taghaboni et al. 95], [Langevin et al. 96] • Local information required, quick in routes finding, small system 6 / 18
Literature Review (cont’d) AGV routing on large scalable systems • Linear path layout: • [Qiu et al 01] • Conflict-free, but low utilization of land space • Loop topology: • [Banerjee et al. 95] [Bozer et al. 91] [Barad et al. 95], [Sinriech et al. 92] • Easy to implement, require little computation, low throughput • Mesh path layout: • [Hsu et al. 94], [Qiu et al. 00] • Conflict-free, extra distance traveled, large time complexity 7 / 18
Literature Review (cont’d) Packet routing on mesh topology • On-line routing: • Central-control model [Gramatikakis et al. 98] • Distributed-control model [Leighton et al. 95] [Sibeyn et al. 97] [Valiant et al 82] • Off-line routing: • [Nassimi et al. 80] [Mou et al. 92] [Krizanc et al. 91] [Kaklamanis et al. 92] 8 / 18
Literature Review (cont’d) Comparisons between AGV and packet routing • Similarities: • Movement patterns: permutation, k-k routing,… • Static and dynamic routing • Randomized and deterministic methods • Other issues: deadlock, live-lock, fault tolerance,… • Differences • Different definitions of link bandwidth at each step • Different sizes of buffers • Packets can be discarded, copied, but not AGV’s loads 9 / 18
Literature Review (cont’d) • New issues • Routing in large scale systems • Energy-efficient routing algorithms • Dynamic routing problems 10 / 18
Outline • Introduction • Literature Review • Off-Line Mesh Routing • Conclusions and Future Work 11 / 18
Off-Line Mesh Routing • # of AGVs= , • Movement pattern: partial permutation • Partition of mesh path layout 12 / 18
Approach Adopted from Valiant’s Algorithm • Valiant’s routing algorithm • From sources to random intermediate nodes • From intermediate nodes to destinations • Use Valiant’s ideas for partial permutation • Distribute AGVs evenly in each group • Shorten the longest distance travelled • Insight of Valiant’s algorithm • Packets are evenly distributed over global network • Packets are routed to their destinations 13 / 18
1 10 19 1 10 17 # # # =3 =3 =3 11 2 18 # # # # # # =8 =8 =8 =2 =3 =2 4 13 22 4 3 12 # # # =3 =2 =3 20 19 7 16 5 13 21 14 6 7 15 23 22 8 16 24 2 11 17 9 5 14 20 AGV destinated to submesh_column 1 AGV destinated to submesh_column 2 8 23 AGV destinated to submesh_column 3 3 12 18 6 15 21 9 24 Distribute AGVs Evenly in Each Group Size of group: x=3 rows of submeshes 14 / 18
Off-Line Routing Algorithm • Phase 1: Distribute AGVs evenly in each group • Phase 2: Route AGVs to destinations • Along submesh row • Along submesh column 15 / 18
Analysis of Off-Line Routing Algorithm • Theorem 6.1 : Our routing algorithm works successfully in 2n+o(n) steps, provided, where, n: size of mesh; : size of submesh; x: size of group; : number of AGVs; 16 / 18
Outline • Introduction • Literature Review • Off-Line Mesh Routing • Conclusions and Future Work 17 / 18
Future Work • Fault tolerance • Energy evaluation model • Movement patterns • k-to-1 • k-to-k • Routing on higher-dimensional mesh • 3D AS/RS(Automated Storage and Retrieval System) 18 / 18
Thanks! Q&A