Going Wireless to Stop Accidents

Aug. 1, 2010
A wireless RFID system can be your safety net when toeing the line of training, awareness and respect for equipment and processes.

Anyone who has worked in a plant for a long time can tell stories about people losing fingers or even being killed simply because the mushroom button or safety pull-cord designed to prevent such accidents could not be reached in time. Such accidents have happened even in OSHA-compliant facilities. Yet, no matter how carefully a system is designed, workers will continue to deviate from specified safety guidelines, rendering themselves helpless in the critical seconds before a tragic workplace accident.

Accident prevention should be a top priority, not only to maintain workplace safety, but to avoid unnecessary costs. Millions are paid each year to those injured on the job. On top of that, consider the cost of punitive damages that can follow such incidents.

The Promise of RFID

Advances in wireless technology make it unnecessary for workers to move somewhere to take the critical steps needed to halt machinery and industrial processes. A line worker wearing a device equipped with radio frequency identification (RFID) technology can not only tell a centralized system where they are, but they can stop equipment, such as conveyors, on a zoned basis.

Such a device could also monitor biometric parameters and physical and environmental conditions, such as levels of chemical vapors, temperature, humidity, or a host of other possible factors. For workers involved in transporting materials, such as a lift truck operator, an RFID- enabled device could also track factors such as speed and acceleration. This would provide automatic reporting of unsafe operation. The device would serve as the electronic equivalent to a “canary in a coal mine.”

Making wireless work

Many systems today can easily be upgraded to accommodate RFID solutions and enable wireless safety mechanisms. On a basic level, enabling RFID requires placing a wireless interface into a machine's control panel or providing a dedicated LAN that interacts with an existing warehouse management system (WMS). This enables the equipment to receive commands wirelessly for a given radius. In other words, it mimics the role of the existing safety mechanisms and associated hardware. RFID systems can be applied to any industrial, worker-driven system using the following components:

  • A compact and wearable Internet protocol-based device, or actuator, powered by an active RFID tag, and multiple sensors,

  • One or more local area network (LAN) access points,

  • A base station server, and

  • The software, which links the actuator device, the LAN access points, the server and all associated machinery together into a seamless integrated system.

Another beneficial feature of wireless technology is its flexibility. The system can be programmed to minimize the technology's impact on day-to-day operations. For example, if a factory floor or distribution center is divided into zones, only employees in a given zone may be able to stop specific equipment or a desired equipment group. If changes necessitate an employee moving from, for example, Zone A to Zone B for a day, the actuator would automatically adjust/re-configure itself to control the set of equipment or desired functions relevant to any given zone.

Material handling scenarios

Scenario 1 - Operator Error

A conveyor feeds a pallet's worth of product onto an accumulation conveyor so that when called for, the system will release it to an automatic palletizer. In some instances, a jam occurs and the line will not discharge. Without thinking of the ramifications, an operator reaches over and/or climbs on the conveyor and forces a conveyor to stop manually with one hand. Suddenly, the conveyor surges forward due to the significant back pressure that has built up. The conveyor catches the worker on the equipment or product. There is a fixed stop somewhere nearby, but the worker is trapped, helpless to halt the machinery.

With RFID, the worker would be able to hit a safety button worn as part of his or her uniform. Or, a co-worker who witnesses the accident could hit his or her own safety button. In another situation, a worker from another area of the plant - perhaps after hearing a call from the trapped worker - could run into the area and stop the mechanism.

Scenario 2 - Overhead Conveyors

One of the most common accidents, in addition to what can happen when manually clearing jams while equipment is operating, occurs when product falls from elevated conveyor lines. This is typically due to product “bridging” due to either a jam or excessive back pressure. Bridging occurs when pressure between individual cases or other product becomes great enough to cause upward movement, forcing material over side rails or guards that normally would contain it safely. People working beneath the line can not see this as it is happening, as it is directly above them. However, workers in the vicinity may see the accident developing from a distance. Due to typically high noise levels in automated facilities, calling out to the co-worker will not help. This forces the witness to “race to the emergency stop” creating an even more dangerous scenario.

Scenario 3 - Equipment malfunction

RFID can also prevent equipment from being destroyed. Most equipment has limit switches, prox switches, photo eyes, etc., designed to detect things like jumped chains or broken drive components. However, these devices do not always work, or may simply not include all scenarios that could result in harm to both the operators and the equipment.

In some cases, the lit STOP button may be impossible or dangerous to reach. The first response is to get out of harm's way. A wearable, RFID-enabled device would allow a worker to stop the equipment while also remaining at a safe distance. Quickly halting a machine, or an entire line, can minimize the potential for catastrophic damage and prolonged down time.


Proper training, safety awareness and respect for equipment and processes are still priorities when it comes to protecting people and operations. However, within the next 10 years, more workplaces will have an RFID-enabled environment to help support these basics.

Lawrence Cuthie is an engineering consultant with more than 20 years of experience in designing automated warehouse systems.

Jay Steinmetz is the president and CEO of Barcoding Inc., a Baltimore, Md., firm specializing in the development and integration of enterprise-wide mobility solutions.

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