Nowadays, underwater vehicles (UVs) are applied to various tasks such as carrying objects or maintenance of underwater structures. To carry out well these tasks, UVs should keep the position and orientation in the water to perform the specified tasks. However, the systems used in underwater operations are always under the influence of disturbance such as ocean currents and model uncertainties. In this paper, the robust station-keeping (SK) control algorithm based on a sliding mode control (SMC) theory is designed to guarantee stability and better performance of a hovering over-actuated autonomous underwater vehicle (HAUV) despite the existence of model uncertainties and ocean current disturbance in the horizontal plane (HP). Using the Lyapunov theorem, the stability of the proposed controller is demonstrated. Besides, an optimal allocation control (AC) algorithm is also designed to keep the linear position and Euler angles of the HAUV in the presence of model uncertainties as well as ocean currents and to minimize the energy consumption of the system. Finally, a series of simulations and experiments for the HAUV system is conducted to demonstrate the superior performance of the proposed method.

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Station-Keeping Control of a Hovering Over-Actuated Autonomous Underwater Vehicle Under Ocean Current Effects and Model Uncertainties in Horizontal Plane

We use the Adams-Bashforth-Moulton scheme (ABMS) to determine the approximate solution of a variable order fractional three-dimensional chaotic process. The derivative is defined in the fractional sense of variable order Atangana-Baleanu-Caputo (ABC). Numerical examples show that to solve these variable-order fractional differential equations easily and efficiently, the Adams-Bashforth-Moulton method can be implemented. Lastly, simulation results demonstrate the proposed robust control’s effectiveness.

On three-dimensional variable order time fractional chaotic system with nonsingular kernel

Disturbance observers and extended state observers for marine vehicles: A survey

In the direct torque control (DTC) of induction motor (IM) drive systems utilizing model predictive torque control (MPTC) in the inner loop and classical proportional integral (PI) control in the outer loop is prone to weaknesses, such as uncertainties, external disturbances, parameter variations, and nonlinear dynamics. A high-performance control system for speed and torque is required to guarantee a smooth and robust control architecture that can withstand such unpredictable effects. In this study, we propose an integral super twisting sliding mode control (ISTSMC) to address the shortcomings of the classical PI used in the outer loop of DTC drive systems. A sliding mode speed observer is also designed and utilized to overcome problems associated with mechanical sensors. The robustness of the proposed control strategy and fast dynamic speed response are compared favorably with a benchmark PI controller and conventional sliding mode control (SMC). The ability of the proposed system to regulate both speed and torque was evaluated through simulations, under various fault perturbations, parameter variations, and load disturbances, conducted in MATLAB/ Simulink. Various performance indices were used to demonstrate the superior performance of the proposed strategy compared to a benchmark PI system and conventional SMC-based MPTC approaches.

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Integral Super Twisting Sliding Mode Based Sensorless Predictive Torque Control of Induction Motor

This paper addresses speed control of permanent magnet synchronous motor under load torque perturbations. The mathematical model is derived using park’s transformation. The load torque disturbance is considered unknown bounded, and states variables are available in feedback. In order to achieve robust speed performance, sliding mode control (SMC) is introduced. However, it is noted that conventional SMC does not provide satisfactory performance under load torque disturbances. To end this, a novel control strategy called disturbance observer SMC (DOSMC) is formulated. It includes an observer that offers a tool to vanish the effect of load torque. The DOSMC technique has two distinguished characteristics: first, the design gains are needed to be greater than the maximum limit of disturbance estimation error instead of disturbances, second; the proposed observer estimates load disturbances and provide a compensator to update sliding surface and control input. The stability analysis of overall control system is verified using Lyapunov theorem. Simulations in MATLAB/Simulink proves efficacy of the proposed scheme.

Disturbance Observer Based Robust Sliding Mode Control of Permanent Magnet Synchronous Motor

Finite-time extended state observer based nonsingular fast terminal sliding mode control of autonomous underwater vehicles

This is an increasing belief that consequences due to hyperglycemia can be mitigated using a close loop control system. This paper investigates a robust non-linear control approach based on sliding mode control (SMC) algorithm for type 1 diabetes patients. Bergman's minimal model have been used to analyse the behaviour of glucose and insulin dynamics in blood plasma inside human body. Control law based on super twisting SMC algorithm is formulated and simulated. Results demonstrated the performance and effectiveness of the proposed control scheme. Also the proposed control scheme is compared with traditional SMC on the basis of performance parameters in the presence of external disturbances. Results dictate that the proposed control law exhibits robustness and overperforms by demonstrating accurate trajectory tracking with relatively less control efforts and alleviating chattering.

Super twisting control algorithm for blood glucose regulation in type 1 diabetes patients

The disturbance observer based stabilization of a generalized linear uncertain system is studied. All the states variables are assumed to be immeasurable and are not available in feedback to the designed controller and disturbance estimator. Firstly, for the purpose of state estimation Luenberger observer is investigated. In addition, to eradicate the influence of norm bounded disturbance a linear disturbance observer is designed in the second step. Finally, an algorithm based on state feedback controller is designed to regulate the states trajectories to the origin. To validate the effectiveness of proposed scheme a numerical example is provided.

State and Disturbance Observer Based Control for a Class of Linear Uncertain Systems

This paper shows the effectiveness of disturbance observer (DO) based sliding mode control (SMC) scheme as compared to traditional SMC. Both the methods are simulated for variable speed win...

Nihad Ali

Papers

Finite-time extended state observer based nonsingular fast terminal sliding mode control of autonomous underwater vehicles

Disturbance Observer Based Robust Sliding Mode Control of Permanent Magnet Synchronous Motor

Super twisting control algorithm for blood glucose regulation in type 1 diabetes patients

State and Disturbance Observer Based Control for a Class of Linear Uncertain Systems

A Disturbance Observer Based Sliding Mode Control for Variable Speed Wind Turbine