1. Planning Motions with Intentions By Chris Montgomery A presentation on the paper Planning Motions with Intentions written by Yoshihito Koga, Koichi Kondo, James Kuffner and Jean-Claude Latombe

2. What is a “Motion with Intention?” A motion for accomplishing some task Non-predictable Cannot be described by laws physics Solves a problem

3. Our Goal To Realize the automatic generation of human and robot arm motions to complete manipulation tasks

4. Our Problem Multi-Arm Manipulation Problem Must find a collision free path for the arms to grasp and then carry some specified moveable object from its initial location to its desired goal Must account for the ability of the arms to change their grasp on the object Necessary to solve all problems

5. Necessary Information to Create a New Path Planner Geometry of the Environment Initial and Goal Configurations Set of Potential Grasps Inverse Kinematics of the Arms

6. Definitions Stable Space The set of all legal configurations where the object is statically stable between contacts (arms, obstacles, etc) Grasp Space The set of all the configurations where one or more of the arms rigidly grasp the object in a way that there is sufficient torque to move the object

7. More Definitions A Transit Path Movement of an arm that does not move the object. A Transfer Path Movement of an arm(s) that moves the object. Some non-grasping arms may also be moving to avoid collisions.

8. More Definitions Manipulation Path An alternate sequence of transit and transfer paths that connect an initial system configuration to a goal system configuration

9. Two-Stage Planning Approach Generate a series of subtasks to achieve the system goal configuration Plan a transit or transfer path for each subtask But how can one determine whether a subtask can be completed without actually completing it?

10. Generating a Path While path is planned, arms are checked to ensure the object can be grasped At every point along the path, the planner keeps a list of possible grasps

11. Generating a path Once a collision free path is found, the planner determines which grasp is valid longest Transit path is planned with this grasp If grasp will not last until the final configuration, right before the grasp becomes invalid the planner is used again

12. Limitations Transit task between two transfer tasks is difficult to solve when ungrasp/regrasp is necessary Intermediate step is necessary

13. Limitations to this process Does not plan for regrasps at configurations where the object makes contact with an obstacle Only probabilistically complete Computation time cannot be bounded in advance—could run forever However, it usually returns a path quickly, so an arbitrary time can be set to determine when a path is not possible