Underwater Tracking and Size-Estimation of a Moving Object Using an IPMC Artificial Lateral Line

Motivated by the lateral line system of fish and amphibians, arrays of flow sensors have been proposed as a new sensing modality for underwater robots. Most existing studies on such artificial lateral lines have been focused on the localization of a vibrating sphere, also known as a dipole source. In this paper we investigate the problem of tracking a moving but non-vibrating cylindrical object and estimating its size and shape using an artificial lateral line system. Based on a nonlinear analytical model for the moving object-induced flow field, a two-stage extended Kalman filter is proposed to estimate the location, velocity, size, and shape of the object. Simulation results on tracking a cylinder with ellipsoidal cross-section are presented to illustrate the approach. On the experimental side, we demonstrate the use of an artificial lateral line prototype comprising six ionic polymer-metal composite (IPMC) flow sensors in the tracking and size estimation of a moving circular cylinder.