Initial experimental investigation of undulating fin

An environment-friendly propulsion system mimicking undulating fins of cuttlefish or stingray has been built. A nonconventional method was considered to model the flexibility of the fins of cuttlefish or stingray. A two-degree-of-freedom linkage was designed and constructed to mimic the actual flexible fin. Several linkages were used to form a mechanical fin consisting of several fin segments, which are able to produce undulations, similar to those produced by the actual fins. A number of experiments were carried out on the mechanical fin attached to a buoyant tank, which mimics a fish. The results were found consistent with anguilliform swimming behavior.