Walking paths during collaborative carriages do not follow the simple rules observed in the locomotion of single walking subjects

Abstract

Some works have already studied human trajectories during spontaneous locomotion. However, this topic has not been thoroughly studied in the context of human-human interactions, especially during collaborative carriage tasks. Thus, this manuscript aims to provide a broad analysis of the kinematics of two subjects carrying a table. In the present study, 20 pairs of subjects moved a table to 9 different goal positions distant of 2.7–5.4 m. This was performed with only one or both subjects knowing the target location. The analysis of the collected data demonstrated that there is no shared strategy implemented by all the pairs to move the table around. We observed a great variability in the pairs’ behaviours. Even the same pair can implement various strategies to move a table to the same goal position. Moreover, a model of the trajectories adopted by collaborating pairs was proposed and optimized with an inverse optimal control scheme. Even if it produced consistent results, due to the great variability which origins were not elucidated, it was not possible to accurately simulate the average trajectories nor the individual ones. Thus, the approach that was shown to be efficient to simulate single walking subjects failed to model the behaviour of collaborating pairs.

From the Study of Table Trajectories during Collaborative Carriages toward Pro-active Human-Robot Table Handling Tasks

“…This means that the average trajectories were at least representative of all the performed carriages in terms of positions. Thus, in contrast with the subjects trajectories which showed a high variability [17], the table trajectories were more reproducible. As a conclusion, the carriage tasks performed by the different pairs resulted in similar trajectories for the table even if the subjects tended to perform various trajectories themselves.…”

“…By doing so, they may optimize the table trajectory rather than their own. This may explain why the IOC succeeded here while the same scheme failed to find optimal cost function weights to model the subjects' trajectories [17]. Then, The table trajectories were smoother than human trajectories as they were not subject to the CoM oscillations induced by footsteps which can be observed when studying human trajectories.…”

“…First, it provides a short analysis of the experimental trajectories performed by a table handled by two subjects. Previous work [17] already showed that the trajectories performed by the subjects are too diverse to be simulated with the same method used to simulate single walking humans [18]. Thus, the present work focuses on the analysis of the table trajectories in order to investigate the variability of those trajectories and the possibility to model the table behaviour instead of the subjects' behaviour.…”