Electrolocation of multiple objects based on temporal sweep motions

Abstract

Weakly electric fish use self-generated electric fields to identify prey, explore their surroundings, and communicate with conspecifics. They have electroreceptors over their entire skin surfaces, and readings from these electroreceptors form electric images. The characteristics of electric images include important information such as the locations, shapes, and electrical properties of target objects. The lateral distance to a target object can be estimated using the rate between maximal slope and maximal amplitude, or relative slope, and provides a direct cue to localize target objects, irrespective of size and electrical properties. Sensor readings acquired from distributions of electroreceptors are interpreted as spatial electric images. Temporal electric images can be assessed using a single electroreceptor by back-and-forth swimming. Some species of weakly electric fish engage in back-and-forth swimming behavior during foraging and can use spatiotemporal information to localize objects. With active body movement and forward swimming, a single electroreceptor can scan the time course of potential perturbation caused by a target object. If there is more than one target object, electric images may be distorted by interactions between individual images. In this paper, we suggest that temporal relative slope is an effective measure for the electrolocation of multiple objects by robotic systems. We investigate the characteristics of temporal relative slopes based on back-and-forth sweeping motions to localize multiple spherical objects via modeling experiments. This method can be applied to biomimetic robotic systems in the underwater environment.