The x-axis of the N frame is assigned to be always along the movement of the end-effector while the y-axis should be horizontal in the world frame. We are able to change the force gain for x, y, z direction in N frame, so that the end-effector would be flexible in those direction.
For peg in hole, we first move the end factor directly above the hole and then drop it with steady gain in x direction and weaker y and z direction, since in y, z direction we want the end-effector to be flexible.
The Zig-zag groove is the most challenging task, since the robot will be easily stuck at the turning point. To solve this, multiple points outside the path have been added as reference points. Since the point to point motion is interpolated as a straight line, more points will reduce the likelihood to be stucked. Making the waypoint outside the path is a strategy to push the end-effector closer to the outside boundary of the turn.
For the egg push, we have strong gain in y, z direction to make sure the end factor wouldn’t slip and a steady x gain, but the time span is long so that it will push hard and slowly so as not to crash the egg.
