This product moves a towel while drying to keep it from stiffening.
A pressure sensor or load-cell may detect when a towel has been replaced on the rack. Then, at certain times, the rod is moved, imparting motion to the towel.
For the S-curve design, it is simply rotated -- one rotation in each direction so as not to dump the towel on the floor. This imparts a good variety of motions.
For the U-curve design, it imparts a kick, which should propagate down the towel. The motion is length-wise. If unidirection motion is insufficient, the rigidty of the rod may be loosened, and each end may kick at different times.
The design trade-offs have to do with power consumption and noise.
Research is needed to determine the optimal strategy during the drying cycle.

For a non-electronic version, one may put a key on the end. Then the user may wind it up, and let it go continuously until the spring runs out.