  Protoplanets and circumplanetary disks are rather elusive in their thermal IR
emission. Yet they are cornerstone to the most popular interpretations for the
protoplanetary disks structures observed in the gas and dust density fields,
even though alternative theories exist. The gaseous velocity field should also
bear the imprint of planet-disk interactions, with non-Keplerian fine structure
in the molecular line channel maps. Such kinks or wiggles are affected by the
optical depth structure and synthesis imaging limitations, but their detail
could in principle be connected to the perturber by comparison with
hydrodynamical simulations. These predictions appear to have been observed in
HD163296 and HD97048, where the most conspicuous wiggles are interpreted in
terms of embedded planets. The velocity centroid maps may allow for more robust
indirect detections of embedded planets. The non-Keplerian velocity along the
planetary wakes undergoes an abrupt sign reversal across the protoplanet. After
subtraction of the disk rotation curve, the location of the perturber should be
identifiable as a Doppler-flip in velocity centroid maps. Here we improve our
rotation curves in an extension to disks with intermediate inclinations, which
we apply to deep and fine angular resolution CO isotopologue datasets. Trials
in HD163296 and in HD97048 yield non-detections. However, in HD100546 we
pick-up a conspicuous Doppler-flip, an important part of which is likely due to
radial flows. Its coincidence with a fine ridge crossing an annular groove
inside the continuum ring suggests a complex dynamical scenario, in which the
putative protoplanet might have recently undergone pebble accretion.
