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AGVs deliver productivity driven by wireless solutions

Manufacturers of AGV systems are choosing AGV systems to effectively address the communications between the central control system and the vehicles themselves. Advanced wireless communications solutions also make AGV systems more reliable in the most demanding environments.

MANUFACTURERS IN MANY INDUSTRIES are investing in automated material handling systems to improve operations and increase worker safety. Automated guided vehicle (AGV) system sales are growing fast, as these systems provide great flexibility to work in a variety of different manufacturing processes. Let′s take a closer look at what AGV systems are, why manufacturers are choosing AGV systems, and how advanced wireless communications solutions make AGV systems more reliable in the most demanding environments.

Ultra-Fast Roaming technology ensures the AGV never experiences more than 10 milliseconds of disconnection while roaming from one fixed radio to the next.

Automated guided vehicles

AGV systems come in many shapes and sizes based on the needs of the operation. Most often, AGVs replace manned material handling vehicles such as forklifts. The AGV system is comprised of a central control system, a navigation system, and multiple vehicles that move about the plant according to the needs of the operation. The vehicles are often customized to the needs of the operation.

AGVs are available as unmanned forklifts, pallet trucks, tuggers, assembly line carriers, and many others. The vehicles communicate to the central control system to receive work orders, and move about the plant with help from the AGV navigation system to complete the work. AGVs deploy a variety of technologies for navigation, as well. The most basic systems follow a fixed path of magnetic tape or marked line on the plant floor. Advances in navigation have added laser and infrared sensors, machine vision, and "natural" guidance that require less installed infrastructure.

With the average AGV system representing a $1 million USD investment, these systems have to deliver on significant operational improvements to justify the expense. Manufacturers invest in AGVs for a few key reasons, and often find quick payback on their investment. Originally, AGVs helped to reduce labor costs. In fact, labor cost makes up 72 percent of the total cost of ownership for a manned forklift. As AGVs became more prevalent, other benefits became apparent. AGVs help to improve worker safety. Hundreds of injuries from forklift operations are recorded each year in the U.S. alone. AGVs also reduce product damage, and the automated system significantly reduces inventory errors. Finally, AGVs are ideal for operation in hostile environments like cold storage warehouses for frozen foods or clean rooms in pharmaceutical production.

A unique "client-repeater" function allows each AGV in the plant to act as a repeater.

Wireless solutions for AGVs

The tremendous growth in automated material handling systems is a sure sign that these systems deliver on the promise of improved operations. Still, system reliability is critical to realizing the value of an investment in an AGV system. AGV vendors and system integrators around the world have turned to technology to address one critical element of the system - wireless communications between the central control system and the vehicles.

Many AGV applications need to transmit I/O signals from each vehicle. I/O traffic does not require a lot of bandwidth, but uninterrupted communication is critical. Even a short 50- to 100-millisecond disruption in the link can cause the I/O system to fault, stopping the AGV in its tracks.

As AGVs move about the plant, their wireless links must "roam" from one fixed radio to another - and these roam events can cause enough delay to trip the I/O system offline. ProSoft RLX2 radios employ Ultra-Fast Roaming technology that ensures the AGV never experiences more than 10 milliseconds of disconnection while roaming from one fixed radio to the next, and does this without any central wireless controller or complicated network configuration.

Another factor for wireless communication reliability in AGV applications is the dynamic nature of the environment. Plants are constantly changing, with people, parts, and machinery moving around, blocking radio paths, reflecting or absorbing radio signals, and generally making things difficult for the AGVs to find a signal to connect. ProSoft addresses this problem with a unique "client-repeater" function that allows each AGV in the plant to act as a repeater. That means that if one AGV finds itself in a location with poor or no connection to the fixed radios, it can direct its transmission through another AGV that will pass the transmission along until it can find a clear signal to the master control system. Using this technology, AGV systems virtually eliminate "dead spots," and can even tolerate the failure of a fixed radio without interrupting the operations.

Finally, technology is helping reduce the risk of installing a new AGV system. Since technology providers such as ProSoft are focused on industrial communications, application expertise can help guide each customer to the best wireless solution for a particular case.

Application engineers perform site surveys to identify the optimum location of fixed radios, ideal antenna selections, and the best channels for minimal interference. Also, solutions that are unique to the industrial market, like radiating cable (leaky feeder) systems. Radiating cable can be an ideal solution for AGVs as the cable can follow the AGV′s path through a plant, providing highly consistent RF signal with minimal risk of interference and reflection issues.

Keith Blodorn is the director of product management at ProSoft Technology.


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