Abstract
We consider the problem of seeking the source of a scalar signal using an autonomous vehicle modeled as the nonholonomic unicycle. This vehicle does not have the capability of sensing its position or the position of the source, it is only capable of sensing the scalar signal at the position of the vehicle sensor, which is offset from the vehicle center. We assume that the signal field is the strongest at the position of the source and decays away from this position. The vehicle does not know the functional form of this field, only that there is a maximum at the source location. We employ extremum seeking to estimate the gradient in real time and steer the vehicle to the point where the gradient is zero (the maximum, i.e. the location of the source). We have developed two control strategies – one which keeps the angular velocity at a constant nonzero value and tunes the forward velocity, and the other which keeps the forward velocity at a constant positive value and tunes the angular velocity. In this paper we present the results for the more practical scheme, tuning the angular velocy. This is more suitable for most autonomous vehicles, including aerial ones. In addition to the local stability proof of the scheme via averaging, we present simulation results for both static and moving sources.
Published Version
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