fig11
From: Designs, motion mechanism, motion coordination, and communication of bionic robot fishes: a survey
Figure 11. The following robot fish saves energy by vortex phase matching. (A) Relative power coefficient: Positive and negative values, respectively, represent energy saving and energy cost relative to swimming alone. The dashed line represents the function between phase difference and front-back distance, as shown in (B). (B) Location of energy saving: The size and darkness of the dots represent the number of times that the energy saving state occurs[50].