Sliding mode control, due to its robustness against modelling imprecisions and external disturbances, has been successfully employed to the dynamic positioning of remotely operated underwater vehicles. In order to improve the performance of the complete system, the discontinuity in the control law must be smoothed out to avoid the undesirable chattering… (More)
The HippoCampus platform is a low-cost micro autonomous underwater vehicle for swarm robotics research. This paper presents the hardware and software design, the communication link, instrumentation, and control system. The quadrotor design enables the vehicle to perform agile maneuvers in a very confined test tank. Vehicle navigation is based on the… (More)
The dynamic behavior of underwater robotic vehicles can be greatly influenced by the nonlinear dynamics of the vehicle thrusters. In this way, the implementation of a good control strategy for the thruster subsystem is essential for the accurate control of the entire robotic vehicle. It was already shown in the literature that without compensation for… (More)
Sliding mode control is a very attractive control scheme because of its robustness against modelling imperfections and external disturbances. It has been successfully employed to the dynamic positioning of remotely operated underwater vehicles. In such situations, the discontinuities in the control law must be smoothed out to avoid the undesirable… (More)
Two models for ship roll motion and capsizing under stochas-tic excitation are analyzed using Melnikov's method and control set analysis. The predictions given by these two methods are compared.
In order to apply the sliding mode control to a remotely operated vehicle (ROV), prior knowledge of exact bounds for parameter uncertainties and external disturbances is a prerequisite. However, these bounds may not be easily obtained because of the complexity and unpredictability of the structure of uncertainties in the dynamics of ROVs. In order to… (More)
Modern ships' large-amplitude roll motions represent a considerable threat to goods and life in today's ocean navigation. The authors investigate an indirectly excited nonlinear oscillator that describes the ship's roll motion and discuss suitable models for wave excitation processes
A hyperbolic acoustic system for underwater robot self-localization is presented. Anchored transducers send acoustic signals which are observed by a receiver. The system is passive with one-way signal transmission. Time differences of arrival (TDOAs) between the emitted signals are estimated by the receiver via cross-correlation. These TDOAs are fed to an… (More)