A Frequency-Limited Adaptive Controller For Underwater Vehicle-Manipulator Systems Under Large Wave Disturbances

Standard adaptive control approaches may not be able to sufficiently stabilize underwater vehicle-manipulator systems (UVMSs) when wave disturbances are large, leading to high-frequency oscillations of large amplitude in its dynamic model parameters. Such parameters bring about undesired oscillations in the vehicle body control and state. This paper extends a frequency-limited adaptive control approach to the vehicle body. An auxiliary model is obtained from the approximated model through a low-pass lifter and is used to reduce the problematic oscillations. The resultant stable vehicle body is a necessary premise for successful end-effector tracking. In addition, this paper proposes a sufficient condition of the control gains for guaranteed asymptotical stability of the controlled robotic system. Numerical simulations have demonstrated the effectiveness of the presented approach, compared to the standard adaptive control.