Question
what are the different methods of vanilla flower pollination

Answer
The following technique was in use years ago when the vanilla orchid was the only source of vanilla extract. At that time, vanilla orchid pollination was done by hand with great efficiency.  The discription of the process is as follows:  push the lip down out of the way and hold the column in the fingers of the left hand.  Using a bit of wood whittled to a point (a solid toothpick might work) in the right hand, lift the rostellar flap that covers the stigma and fold it upward.  With the left thumb, in one downward motion, mash the pollinia (ie the entire anther) down onto the stigma. (You may be aware that the stigma is on the upper surface of a small "shelf" and is covered by this shield called the rostellum which must be lifted in order to expose the stigmatic surface).

You may need to practice this some.  Good luck.