Reducing postural load in order picking through a smart workwear system using real-time vibrotactile feedback

A Wearable Sensor System for Physical Ergonomics Interventions Using Haptic Feedback

“…A substantially reduced proportion of accumulated time was observed among the participants when provided solely with verbal ‘ergonomic’ instructions (24–41%) and reduced further when provided with haptic feedback training in combination with verbal ‘ergonomic’ instructions (36–65%). This reduction in accumulated time in upper-arm elevation related to the haptic feedback is larger than has been observed previously, where reductions in accumulated time in upper-arm elevation angles of 4–32% were observed [ 69 ]. These differences might reflect the proportional postural load attributed to the individual work technique, hence the potential that can be targeted by using the haptic feedback training for work technique improvements.…”

“…Additionally, the total feedback training period in the current study and in Lind et al [ 69 ] was less than 15 min, so the effect on reduced productivity is limited and should rather be compared with the time needed when using other training programs. Interestingly, no significant difference was observed in the accumulated time of upper-arm elevation when comparing the first and second haptic feedback sessions ( Figure 9 a), or when comparing the first and second verbal instruction sessions.…”

“…Previous studies from industrial type manual handling operations have shown significantly longer task execution times when receiving direct feedback training [ 45 , 69 ], which may be attributed to actions taken to alter the work technique. Given that increased task execution time reduces productivity, the increased execution time can have negative effects on work performance.…”

“…The haptic feedback unit with the integrated Bluetooth transmitter was positioned approximately 5 cm distal of the IMU on the participants’ dominant arm and secured by using a semi-elastic textile strap ( Figure 3 b). The reference position for the upper arm (to denote 0° upper-arm elevation) was recorded with the subject standing upright, looking forward at eye-level, and with relaxed arms hanging down and with the palms facing towards the body [ 38 , 69 ]. Only postural data from the dominant arm were used for the haptic feedback as well as for evaluating the effect of the haptic feedback training.…”

“…The Smart Workwear System is an ambulatory and flexible sensor-based technical solution targeting work-related physical and psychosocial stressors that can have adverse or promoting effects on health and direct or indirect effects on work performance. Depending on the targeted exposure type, suitable sensors can be used, including the following: accelerometer-based sensors, IMU sensors, or strain sensors for monitoring human movement and postures [ 69 ]; electrocardiogram and thoracic electrical bio-impedance sensors for monitoring the heart rate, respiratory rates, energy expenditure, or heart rate variability [ 44 ]; pressure sensors for monitoring force exertions; electromyography (EMG) sensors for monitoring muscle activity levels, muscle rest (gaps), muscle activity variability, or muscle fatigue. This diversity makes the system usable for a large variety of applications, and previous applications where the system has been tested include healthcare, industrial manufacturing, construction, office work, service, and transport, with tasks ranging from driving, computer work, postal delivery, and assembly operations, to order picking and cleaning [ 44 , 47 , 69 , 70 , 71 ].…”