t = 20 s ∆z Layer 1 Layer 2 Actuated Static (a) t = 20 s t = 20 s ∆z ∆z Layer 1Layer 2Layer 1Layer 2 Actuated Actuated 0.02 Initial Configuration Option 1 Option 2 0.01 (b) Actuated Actuated (c) Figure 10. The increased performance arising from the optimal detachment of a feather. Starting from (a) the initial configuration, we can achieve (b) a higher speed in the z direction by detaching one feather and actuating both layers. (c) A comparison of the performance results. for when and how to alter the body to achieve a change in functionality. The results presented show an initial exploration of using " detachment " inspired by mutable tissues as a means of changing the body. This allows the robot to have a timevarying design space. Expanding this capability to allow not only detachment but also retrieval or growth would further 90 * IEEE ROBOTICS & AUTOMATION MAGAZINE * DECEMBER 2022 expand this concept and bridge the gap to reality. In addition, increasing the physical complexity of the robot, for example, increasing the number of layers, would allow a larger and more complex control space to be explored. Testing and evaluating the robot in a large body of water would also enable longer trajectories to be studied and provide a means of evaluating the maneuverability of the system Velocity (m/s)