Measuring the effects of lighting distribution on walking speed and head pitch with wearable inertial measurement units

A comparative human performance evaluation of a miner´s walking speed and head pitch was conducted on miners wearing two types of LED cap lamps. Walking speed and head pitch are indirect indicators of improved lighting. The better that miners can see the floor, the faster they can walk and the less they pitch their heads downward to illuminate the floor with their cap lamps. NIOSH researchers developed a non-contact way to quantify human performance by using two small wireless, wearable inertial measurement units. Data were collected in the field from nine coal miners in an underground coal mine. The field results showed no statistical difference between the two cap lamps for walking speed. However, there was a trend of 2° lower head pitch for one of the cap lamps. The field testing procedures were then replicated in a controlled laboratory environment and the results indicated a 5-degree lower head tilt when using the same cap lamp and a corresponding difference in walking speed. A novel application of magnetometers for distance flagging is also presented. Finally, study limitations and a follow-up study are discussed.