Templates for pre-grasp sliding interactions

In manipulation tasks that require object acquisition, pre-grasp interaction such as sliding adjusts the object in the environment before grasping. This change in object placement can improve grasping success by making desired grasps reachable. However, the additional sliding action prior to grasping introduces more complexity to the motion planning process, since the hand pose relative to the object does not need to remain fixed during the pre-grasp interaction. Furthermore, anthropomorphic hands in humanoid robots have several degrees of freedom that could be utilized to improve the object interaction beyond a fixed grasp shape. We present a framework for synthesizing pre-grasp interactions for high-dimensional anthropomorphic manipulators. The motion planning is tractable because information from pre-grasp manipulation examples reduces the search space to promising hand poses and shapes. In particular, we show the value of organizing the example data according to object category templates. The template information focuses the search based on the object features, resulting in increased success of adapting a template pose and decreased planning time.

► Pre-grasp interaction adjusts object placement in the scene to improve grasp success.
► Examples of human pre-grasp actions are adapted to synthesize actions for new objects.
► Organizing examples into template categories by object attributes focuses the search.
► Template-based planning improved adaptation success and decreased planning time.
► Successful grasps of difficult objects are demonstrated on physical humanoid robots.