Human motion in cooperative tasks: Moving object case study

This paper describes results obtained in a preliminary investigation of a cooperative task consisting, for a pair of human operators, in moving a handle-shaped object between two predefined locations on a table. Seated, the operators use only upper body with single hand and arms in achieving this task. In a first step, each subject realized the task in a standalone mode. In a second step, pairs of subjects realized a similar task in a cooperative way. We used standalone results as a reference model to be compared with results obtained from cooperative experiments. Obtained results revealed that it is difficult to fit the minimum jerk model as a task motion characterization in both standalone and cooperative modes. However, we found an invariant velocity shape both for standalone and cooperation situations that can be used as a basic model for a robotic implementation. We noticed that the shape of the parabolic trajectory is always higher in cooperative tasks, although the weight of the object used in cooperative mode is exactly twice the one used in a standalone mode.