This paper deals with the control of underactuated autonomous underwater vehicles (AUVs). AUVs are needed in many applications such as the exploration of oceans, scientific and military missions, etc. There are many challenges in the control of AUVs due to the complexity of the AUV model, the unmodeled dynamics, the uncertainties and the environmental disturbances. A trajectory tracking control scheme is proposed in this paper; this control scheme is designed using the sliding mode control technique in order to be robust against bounded disturbances. The control performance of an example AUV, using the proposed method, is evaluated through computer simulations. These simulation studies, which consider different reference trajectories, show that the proposed control scheme is robust under bounded disturbances. Keywords autonomous underwater vehicles • AUV • underactuated • trajectory tracking • sliding mode control

No abstract

This paper deals with the sliding mode control of a three-dimensional overhead crane. The model of the crane consists of five highly nonlinear second-order ordinary differential equations. The crane is an underactuated system, which makes the design of its controllers intricate. A sliding mode control scheme is proposed for the crane. This scheme, which guarantees the asymptotic stability of the closed-loop system, has two objectives: position regulation and anti-swing control. The performance of the closed-loop system is simulated using MATLAB. The simulation results indicate that the proposed control scheme works well. In addition, the robustness of the controller with respect to uncertainties in the crane parameters is investigated through simulations. It is found that the controller is robust to changes in the parameters. Moreover, since some of the states of the system are not measurable, a Luenberger-type observer is proposed. Simulation of the controlled system using the observer-based sliding mode controller produced good results.

No abstract

No abstract