Environment-contacting task by position-controlled manipulator using free-joint structure

In general, environment-contacting manipulation task such as assembly requires a force-controlled manipulator. In this paper, a method is introduced to achieve environment-contacting task with a position-controlled manipulator. Additional mechanism with some free-joint mechanism on wrist of a manipulator reduces excessive inner force. We show conditions to reduce excessive inner force and to keep high rigidity of object. An experiment of graspless manipulation with free-joint mechanism is shown as an example of this research