(2)① The total route length of vertex O is:

90π× 1 180×2+90π×2 180=π+22π=2+22π,

② The total route length from ①: vertex O per turn is: 2+22π,

from 4 1+2022π= 20(2+2)2π+π2

That is to say, after 20 weeks, turn it over again, * * * 8 1 time.