Adaptive Field Gradient Estimation Based Extremum Circumnavigation

This paper studies adaptive steering control of a sensory vehicle toward a planar circumnavigation orbit around a signal field source using the signal intensity measurements of the vehicle along its motion path. The signal field is approximated by a quadratic function of location, and has its extremum (maximum) at the signal source location. The proposed adaptive motion control design is based on on-line estimation of the gradient parameters of the signal field. Stability analysis is provided for the proposed adaptive estimation and motion control schemes, establishing asymptotic convergence of the gradient parameter estimates to their true values and settlement of the vehicle on an orbital trajectory on which the signal intensity is equal to a predefined constant value. Simulation test results verify the established properties of the proposed scheme as well as robustness to signal measurement noise.