Inserting Nuts and Bolts
Every bolt has a LCS_bolt It is attached to the lower surface of the head and its x direction points in axial direction towards the thread.
Inserting a bolt means to establish a fixed joint with reference 1 being a circular arc (perimeter of the hole) and reference 2 being the attachment edge of the LCS in the bolt. The angular offset is modified in order to have random orientations of the bolt heads.
The bolt is to be inserted such that the thread points toward the inside of the counterpart. For this we find the attached cylindrical face of the hole and compute its center of gravity. The scalar product between LCS_bolt.x and the vector from the perimeter center to the cog tells whether the joint should be flipped or not.