Meeting Abstract
Antagonistic forces have been shown to lead to an increase in both stability and maneuverability. For example, weakly electric knifefish, which swim by undulating an elongated fin, produce two counter-propagating waves along the fin when swimming at low velocities. Changes in the location where these waves meet (called the nodal point) along the fin allow the fish to rapidly maneuver forward and backward. These fish are able to follow oscillations of a moving enclosure to remain hidden. We observe that the fish can track enclosure movements up to two hertz by rapidly shifting the nodal point, often at even higher frequencies. Experiments on a robotic ribbon fin show that as the frequency of the nodal point shift increases, the force amplitude also increases. In other words, the force gain can be increased through dynamic movements of the nodal point and could be useful when heightened maneuverability is needed. Also, the increased counteracting forces are able to better reject perturbations, leading to increased stability.
