1. COMP322/S2000/L281 Task Planning Three types of planning: l Gross Motion Planning concerns objects being moved from point A to point B without problems, i.e. movement of manipulator without collision with obstacles l Grasping Planning concerns l where to grasp the object so that no collision will occur l the grasp configurations so that object will not fall off the gripper during transportation l Fine Motion Planning concerns the motions of the robot when it is l approaching a surface, i.e. guarded motion; and l in contact with a surface, i.e. compliant motion

2. COMP322/S2000/L282 Gross Motion Planning l Concerns objects moving from Point A to Point B without collision ==> obstacle avoidance problem l Gross in the sense that there is no contact of the robot with any parts l Objective is to plan a path to move a part from an initial position and orientation to a final position and orientationnin the presence of obstacle without colliding with the obstacls. l The planned path should be optimal, e.g. the shortest one. l In general, path planning is a search in the 6-Dimension space (3 translational and 3 rotational). However, the no. of degrees of freedom is usually less than 6. Why? l Configuration space is needed before an optimal path can be defined.

3. COMP322/S2000/L283 Gross Motion Planning (cont’d) Configuration space defines the positions and orientations of the part (both initial and final) and the obstacles. Path Planning is to define the explicit free space in the configuration space for the object to move from the intitial location to the final location. One possible approach: l Shapes and sizes of part (to be moved) and obstacles (stationary) are known l To define the configuration space, the moving part is “shrinked” to a reference point (e.g. centroid) while the obstacles are “grown” to compensate the lost. l Once the configuration is defined, the optimal path can be found. Example (Given in class)

4. COMP322/S2000/L284 Grasping Planning Concerns l where to grasp the object so that no collision will occur and l the object will not fall off during transportation. Three main considerations: l Safety - collision free, contact free; l Reachability - able to reach initial configuration, with object in the gripper, move in a collision free path to the final destination; and l Stability - the grasp should be stable in the presence of forces exerted on the object while in motion.

5. COMP322/S2000/L285 Grasping Planning (cont’d) Three main goals: l must identify a single configuration, i.e. position and orientation of the gripper; l must consider the detailed interaction of the gripper‘s shape, surfaces of contact; and l must deal with the interaction of the choice of grasp consideration and the constraints imposed by the sequence of operations Most approaches consist of three steps: l choose a set of potential grasp configurations; l Prune those that are not reachable by the robot or may lead to collision; and l choose the optimal from the remaining ones.

6. COMP322/S2000/L286 Grasping Planning (cont’d) Note: l These approaches assume the configurations of objects are known l With the help of sensors, e.g. vision, configurations of objects can be computed l Touch sensors are often used to achieve the actual grasping of the objects.

7. COMP322/S2000/L287 Fine Motion Planning l Concerns the motions of the robot when it is l approaching a surface ==> guarded motion l in contact with a surface ==> compliant motion l Force and tactile sensors are usually used Guarded Motion l Movement along a specific direction until certain event occurrs Compliant Motion l After contact, the type of motion must comply with the constraints imposed by the surface l Motion is usually continuous and guided by contact with the surface Example (given in class)