A Relationship between Movement Time and Traveled Distance during Smooth Cooperative Object Transfer by Two Humans*

Abstract A smooth manipulator motion is desired to work cooperatively with human hand in transferring an object. In this article, a relationship between movement time and traveled distance of a cooperative object transfer performed by two humans using their right hands in a seated position was investigated. The relationship will be utilized with a minimum jerk model to generate a smooth cooperative manipulator motion in human-robot cooperative system. The cooperative task was done in leftward/rightward, upward/downward and forward/backward direction relative to the Leader. The results indicated that movement time and traveled distance were positively correlated. The relationship between movement time and traveled distance was represented using a regression line. The difference between Leader’s and Follower’s relationship was relatively higher in leftward/rightward compared to upward/downward direction. In contrast, in forward/backward direction, both subjects show similar relationship. The difference in relationship between sub-direction, major directions and groups could not be identified. In facilitating the selection of the best relationship for the robot Follower, an average regression line representing all Followers motion in each sub-direction was indentified. In the next phase of the human-robot experiment, all human Leaders from this experiment will be tested with the manipulator motion programmed with the average regression line. Moreover, the parameters of the average regression line will be varied beyond the maximum and minimum values of human Follower’s regression line parameters obtained in this experiment.