Fig. 2: Learning primitive swimming skills: propulsion and reorientation.
From: Chemotactic navigation in robotic swimmers via reset-free hierarchical reinforcement learning
a A chain swimmer achieves propulsion through symmetric beating, with vectors indicating the flow field. The inset shows the horizontal (x) and vertical (y) displacements of the swimmer’s tip, resembling a traveling transverse wave. b The chain swimmer reorients through asymmetric actuation. c A ring swimmer propels by periodically contracting and expanding its body. The inset displays the x and y displacements of the swimmer’s front, typical of a longitudinal wave propagating horizontally. d Evolution of front-rear pressure differences during the policy iteration process: training the chain swimmer for propulsion (purple solid line) and reorientation (purple dashed), and the ring model for propulsion (green solid in the inset). This quantity is time-averaged over one policy. e, f Similar to d, but for the rotational rate and centroid translational velocity of the swimmers, respectively. The latter reaches a plateau value (dashed line), \({\mathcal{U}}/(\hat{\Omega }L)\), representing the swimming speed of simulated agents once training has converged. Source data are provided as a Source Data file.
