Biologically-inspired adaptive pectoral-like fin control system for CFD parameterized AUV

This paper treats the question of adaptive control of a biorobotic autonomous underwater vehicle (BAUV) in the yaw plane using biologically-inspired pectoral-like fins. The fins are assumed to be oscillating harmonically with a combined linear (sway) and angular (yaw) motion. The bias (mean) angle of the angular motion of the fin is used as a control input. Oscillatory fins produce periodic time-varying control forces and moments. It is assumed that the physical parameters, the hydrodynamic coefficients, and the fin force and moment are not known to the designer. Using a discrete-time state variable representation of the BAUV, an adaptive sampled data control system for the trajectory control of the yaw angle using state feedback is derived. The parameter adaptation law is based on the normalized gradient scheme. In the closed-loop system, time-varying yaw angle reference trajectories are tracked and all the signals in the closed-loop system remain bounded. Simulation results for the set point control and sinusoidal trajectory tracking are presented, which show that the control system accomplishes precise trajectory control in spite of the parameter uncertainties, and the inter sample segments of the yaw angle trajectory remain close to the discrete-time reference trajectory.