By combining contactless power supply, drive-based controls, wireless Ethernet, bar codes, and software, engineers at SEW-Eurodrive (Lyman, S.C.) have developed an electric monorail system (EMS) that is more flexible, cleaner, and requires less maintenance than traditional overhead material handling systems. Initially designed as an off-floor material supply conveyor for the automotive industry, the EMS system is now being adopted for other assembly operations, food and beverage packaging, distribution warehouses, and airport logistics. The system handles both light and heavy loads and single or multi-axis applications.
In short, trolleys travel an aluminum track marked with unique bar codes every 2.5 in. for absolute positioning control; the track itself carries electrical wires and a leaky wave antennae cable that transmit power, visualization, diagnostics, and communications over an air gap, for close-range wireless communications that don’t contaminate surroundings with noise, interference, or even mechanical contaminants, for that matter. The highly rugged setup also eliminates points of failure associated with sensors, chains, and bus bars. The electric monorail design showcases decentralized intelligence; each trolley carries its own drive, controls, communications, and power electronics, allowing it to operate independently, chart its own path, and adapt to changes in production requirements or process variables. Controls are governed by parametrics rather than programming, simplifying installation and startup. The client-server architecture provides a central database for data storage, parameter changes, diagnostics, startup, and unit replacement. Time-sensitive functions such as absolute positioning can be realized independent of central program run times.
Functioning much like a railroad switching yard, loads can be shifted onto different tracks or move in a horizontal or vertical direction. Additional tracks can be installed to expand an existing material handling system or accommodate new process variations. In addition, tracks and other system components simply snap together, speeding installation. The only screws required are at the beginning or end of the track. The system can accommodate flat, round, and rotating pickups, depending on application requirements.
Similar to this EMS design, SEW’s original automated guided vehicles (AGV) system transmits electrical energy over an air gap. Cables are buried in the floor and power mobile vehicles and their control systems, so no batteries are required. And whether electric cables are buried under the floor or attached to an overhead track, contactless energy transfer eliminates the wear and tear on cables, such as bunching and slippage that can damage conductors and cause maintenance problems in traditional mobile material handling systems.
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