Back loading estimation during team handling: Is the use of only motion data sufficient?

Antoine Muller,Philippe Corbeil

doi:10.1371/journal.pone.0244405

Abstract

Analyzing back loading during team manual handling tasks requires the measurement of external contacts and is thus limited to standardized tasks. This paper evaluates the possibility of estimating L5/S1 joint moments based solely on motion data. Ten subjects constituted five two-person teams and handling tasks were analyzed with four different box configurations. Three prediction methods for estimating L5/S1 joint moments were evaluated by comparing them to a gold standard using force platforms: one used only motion data, another used motion data and the traction/compression force applied to the box and one used motion data and the ground reaction forces of one team member. The three prediction methods were based on a contact model with an optimization-based method. Using only motion data did not allow an accurate estimate due to the traction/compression force applied by each team member, which affected L5/S1 joint moments. Back loading can be estimated using motion data and the measurement of the traction/compression force with relatively small errors, comparable to the uncertainty levels reported in other studies. The traction/compression force can be obtained directly with a force measurement unit built into the object to be moved or indirectly by using force platforms on which one of the two handlers stands during the handling task. The use of the proposed prediction methods allows team manual handling tasks to be analyzed in various realistic contexts, with team members who have different anthropometric measurements and with different box characteristics.

Highlights

Team handling occurs when two or more people are involved in a manual handling task
Three different prediction methods were used to estimate back loading: one used only motion data, another used motion data and the traction/compression force applied to the box and the third used motion data and the ground reaction forces of one team member
The three prediction methods differed in the type of experimental input data used: M1 used only motion data, M2 used motion data and the traction/compression force applied to the box and M3 used motion data and one team member’s ground reaction forces (GRF)

Summary

Introduction

Team handling occurs when two or more people are involved in a manual handling task. Team handling is common in many occupations, such as the military [1], the medical field for patient transfers [2,3,4,5,6,7], the construction industry [8, 9], and by movers [10]. The team movement strategy emerges from the interaction of the task, the environment, and the individuals. Particular task constraints, such as handling a heavy or bulky load, often affect team handling.

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