Sensor Technology Could Help Detect Fatigue

The physical demands of advanced manufacturing can lead to worker fatigue, which can result in worker injuries and loss in productivity. Body sensors could help detect signs of fatigue and call attention to the need for interventions, according to a study released by the American Society of Safety Professionals (ASSP).

A three-year study led by Dr. Lora Cavuoto at the University at Buffalo and Dr. Fadel Megahed at the Farmer School of Business at Miami University of Ohio examined three areas of research:

• Surveying manufacturing workers about the prevalence of fatigue,
• Experimenting with body sensors to detect and measure fatigue, and
• Evaluating the effectiveness of various fatigue interventions.

Nearly 58% of workers surveyed reported experiencing fatigue in the previous week, Cavuoto and her colleagues found. The most frequently affected body parts were ankles/feet, eyes, and the lower back. The most frequently cited root causes were lack of sleep, shift schedule, and work stress.

Respondents reported coping with fatigue by drinking caffeinated drinks, stretching or doing exercises, and talking with coworkers.

Using Wearable Sensors

Cavouto and her team concluded from their experiments in body-sensor monitoring that manufacturing-sector employers should invest in data-driven assessments to prevent occupational injury. The use of wearable sensors can detect physical fatigue in a number of different occupational settings. By monitoring body movements, wearable sensors can detect the starting point of fatigue and alert workers and employers to the need for individualized intervention.

However, Cavouto and her colleagues suggested a number of cautions in the use of wearable sensors in the workplace:

• Work through unions and employee organizations to gain buy-in;
• Provide employees with detailed information on how the data collected from sensors will be used;
• Allow employees the option to not share their data or completely opt-out of the monitoring program;
• Do not use wearable sensors for productivity monitoring; limit their use to safety and wellness programs; and
• Train users on proper wear and maintenance of the sensors.

In an experimental study, each participant (out of 28, 10 females and 18 males) was outfitted with four inertial measurement units (IMUs) placed on the chest, hip, wrist, and ankle.  Participants were given a series of tasks to perform during three-hour sessions of continuous work. The tasks included a:

• Low-level assembly task completed in a standing position at a workstation,
• Medium-level task involving supply pickup and delivery with sustained back flexion at the delivery point, and
• High-level task involved manual materials handling with order picking.

The report suggested using data from body sensors could fill in some of the current knowledge gaps in ergonomics.

What Might Work

The third part of the report examined studies of fatigue interventions to try to identify effective ones. Cavouto and her team reviewed 23 controlled trials examining 14 physical fatigue interventions. They concluded that only a handful of inventions helped alleviate specific types of worker fatigue:

• Posture variations showed strong evidence of lowering the development of muscle fatigue in office workers seated for prolonged periods;
• High-dose intravenous vitamin C reduced overall fatigue and dietary supplements containing bilberry extract relieved eye stress caused by video display terminals; and
• Brief and frequent rest breaks (as short as one to two minutes, as frequently as every half hour) countered fatigue from long work shifts.