In recent times, renewable energy demand is rapidly increasing worldwide. Offshore wind energy is one of the alternative solutions to the problems posed by non-renewable energy resources. The kinetic energy of the wind is converted to mechanical energy by using an offshore floating wind turbine (OFWT). The efficiency of the OFWT is dependent upon the vibrational effect induced by the environment. In this paper, for the mitigation of this vibrational effect, a new model of barge-type OFWT is designed by using an active control strategy called translational oscillator with a rotational actuator (TORA). The disturbance observer (DO) based advanced control techniques including robust backstepping sliding mode control (BSMC), backstepping integral sliding mode control (BISMC), backstepping nonsingular terminal sliding mode control (BNTSMC), and a new backstepping integral nonsingular terminal sliding mode control (BINTSMC) technique, are devised for the stabilization of OFWT model. The comparison of these techniques is carried out by using MATLAB/SIMULINK which validates the feasibility and correctness of the proposed OFWT model and control techniques.

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A composite disturbance observer based control (CDOBC) technique for a quadrotor attitude is presented in this paper. The structure of CDOBC consists of a robust equivalent controller constructed using adaptive backstepping sliding mode control (ABSSMC), disturbance observer (DO) and an auxiliary gain to combine controller and NDO. In order to construct the DO, it is assumed that the quadrotor attitude model is effected by unknown bounded disturbances. During the development of DO, a state estimator is also constructed to avoid the situation of lack of states availability. Hence, invoking state estimator in estimation criteria followed by combining it with control scheme through an auxiliary gain yields the desired CDOBC based on ABSSMC. To analyze the dynamic and steady state performance of the developed control scheme, a stability proof followed by the simulation study is presented. In addition, before concluding the effectiveness of developed CDOBC, a comparative analysis is conducted by developing CDOBC based on backstepping and adaptive sliding mode control methods.

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Underactuated translational oscillator with rotational actuator systems are simplified mechatronic systems introduced to investigate the despin maneuver phenomenon for dual-spin spacecrafts in mechanical engineering. The conventional research work for translational oscillator with rotational actuator systems mainly focuses on stabilizing control of equilibrium points. In this article, an orbitally stabilizing control strategy is proposed to steer oscillating movements of a translational oscillator with rotational actuator system. Based on the natural periodicity of translational oscillator with rotational actuator system self-sustained oscillation, the dynamics is analyzed to derive the periodically orbital functions of the translational oscillator with rotational actuator system. Then, a proper control Lyapunov function following the principle of energy conservation is designed to obtain orbitally stabilizing controller for target periodical oscillation orbits of the translational oscillator with rotational actuator system. Finally, the validity of the presented control strategy is demonstrated via the simulations and experiments.