Adjustments in Shoulder and Back Kinematics during Repetitive Palletizing Tasks

Abstract

Repetitive task performance is a leading cause of musculoskeletal injuries among order-picking workers in warehouses. The repetition of lifting tasks increases the risk of back and shoulder injuries among these workers. While lifting in this industry is composed of loaded and unloaded picking and placing, the existing literature does not address the separate analysis of the biomechanics of the back and shoulder for these events. To that end, we investigated the kinematics of the back and shoulder movements of nine healthy male participants who performed three sessions of a simulated de/palletization task. Their back and shoulder kinematics were sensed using an optical motion capture system to determine the back inclination and shoulder flexion. Comparison of the kinematics between the first and last sessions indicated statistically significant changes in the timings, angles, coordination between the back and shoulder, and moments around the shoulder (p<0.05). The majority of the significant changes were observed during the loaded events, which confirms the importance of the separation of these events for biomechanical analysis. This finding suggests that focusing worker evaluation on the loaded periods can provide important information to detect kinematic changes that may affect musculoskeletal injury risk.

Biomechanical Assessments of the Upper Limb for Determining Fatigue, Strain and Effort from the Laboratory to the Industrial Working Place: A Systematic Review

“…The physiological effects of fatigue during repetitive movements, overhead tasks and posture maintenance have been investigated in order to find indicators that can be used to identify fatigue during working activities. Joint angles and torques, especially at shoulder level, significantly reduce with fatigue [ 29 , 30 ]. Moreover, fatigue influences joint coordination that has to compensate for kinematic changes to maintain the trajectory of the end effector [ 31 ].…”

“…Some studies, instead, directly measure when FSE are found. Most of the studies reported that fatigue is found in industrial tasks in working places [ 150 , 167 ] but also in simulated environments [ 29 , 32 ]. In a limited number of studies, the effects of FSE were not observed or they were under the limit for high risk of MSD development [ 117 , 136 ].…”

“…From the screening of the papers, the studies taking place in laboratories were principally observational or were pilot studies in which new tools and supporting devices were tested or some biomarkers for FSE were identified [ 29 , 32 , 33 ]. Future directions should foresee more structured and comprehensive studies involving large cohorts of participants, developed starting from pilot studies already available so that more reliable conclusions can be drawn.…”

Deep Learning-Based Intelligent Forklift Cargo Accurate Transfer System

“… When the intelligent forklift inserts the pallet, there are problems of high implementation cost [ 5 ], low algorithm robustness and insufficient accuracy for the calculation of the relative position between the pallet and the forklift. When controlling the intelligent forklift to insert the pallet after the accurate position is calculated, a fixed control amount is usually used without considering the vehicle running state, which makes the control process deviate and eventually leads to errors in the inserting results [ 6 ]. …”

“…When controlling the intelligent forklift to insert the pallet after the accurate position is calculated, a fixed control amount is usually used without considering the vehicle running state, which makes the control process deviate and eventually leads to errors in the inserting results [ 6 ].…”