An empty gripper can clear an obstacle. The block it picks up might not.
I’ve worked on block stacking with a Kinova Gen3 Lite, and it’s a useful example of a planning detail that’s easy to overlook.
Once the robot picks up a block, the arm and gripper aren’t the only things moving through the workspace.
The block needs clearance too.
A path that works before the grasp might not work afterward, especially if the object extends beyond the fingers.
MoveIt, which
@PickNikRobotics contributes to, lets you attach the block’s collision geometry to the gripper in the planning scene.
Collision checks can then account for the space the block occupies as the arm moves. Closing the physical gripper alone doesn’t give the planner that information.
After placement, the scene needs updating again. The object is back in the environment, not attached to the hand.
I like this because it makes a simple pick-and-place sequence more interesting to watch.
It’s not just reach, close, move, release.
The planner’s model of the workspace has to change along with the task.
Getting a good grasp matters. So does remembering what’s now sticking out of the gripper.
#Robotics #MoveIt #MotionPlanning #ROS2