Hull Design for ROV with Four Thrusters (X4-ROV)

In this research, an X4-ROV consisting of four thrusters is design to develop a small ROV which does not have any rudders for an observation class unmanned underwater vehicle system. Each thruster is arranged at equal intervals to the same plane, and the attitude motions of a roll, a pitch and a yaw, and the translational motion forward are realizable by changing the rotational speeds of four thrusters. In this paper, the construction of an X4-ROV system and the motion method are described, together with the added mass. A torpedo hull shape with four thrusters is draft using solidworks for fabrication of hull (body) shape using a 3d printer. The operator will communicate with ROV via open source platfor

Robust nonlinear control of a buoyancy-driven airship system using backstepping integral sliding mode control

This paper presents the development of nonlinear robust control based on backstepping and sliding mode control system to control a longitudinal plane of a new concept of airship. Nature of autonomous airship is non-rigid body, very nonlinear and therefore control strategy can be used to accommodate the nonlinearities in the airship model. The performance of the proposed controller is simulated using MATLAB/Simulink software which tested for nominal system, system with external disturbance and system with parameter variation to evaluate its robustness against external disturbance and parameter variations. The controller is designed for the gliding path from 10° downward to 10° upward. The performance of proposed controller is compared against the performance of backstepping sliding mode control and integral sliding mode control in terms of chattering reduction and steady state error. The simulation results have shown that the proposed controller has improved the output tracking performance around 25% better as compared to lowest performance of integral sliding mode and the undesired chattering in control input and sliding surface has been reduced almost 100%

Review of sliding mode control application in autonomous underwater vehicles

973-984This paper presents a review of sliding mode control for autonomous underwater vehicles (AUVs). The AUVs are used under water operating in the presence of uncertainties (due to hydrodynamics coefficients) and external disturbances (due to water currents, waves, etc.). Sliding mode controller is one of the nonlinear robust controllers which is robust towards uncertainties, parameter variations and external disturbances. The evolution of sliding mode control in motion control studies of autonomous underwater vehicles is summarized throughout for the last three decades. The performance of the controller is examined based on the chattering reduction, accuracy (steady state error reduction), and robustness against perturbation. The review on sliding mode control for AUVs provides insights for readers to design new techniques and algorithms, to enhance the existing family of sliding mode control strategies into a new one or to merge and re-supervise the control techniques with other control strategies, in which, the aim is to obtain good controller design for AUVs in terms of great performance, stability and robustness

Backstepping control of nonholonomic car-like mobile robot in chained form

This project is attempts to stabilize an underactuated system based on the backstepping approach. The discontinuous time-invariant state feedback controller is designed for exponential stabilization of underactuated nonho-lonomic systems in chained form. System dynamic of the car-like robot with nonholonomic constraints were employed. The validity of the proposed ap-proaches is tested through simulation on a car-like vehicle using Matlab soft-ware

Nonlinear robust integral sliding super-twisting sliding mode control application in autonomous underwater glider

1016-1027The design of a robust controller is a challenging task due to nonlinear behaviour of the glider and surround environment. This paper presents design and simulation of nonlinear robust integral super-twisting sliding mode control for controlling the longitudinal plane of an autonomous underwater glider (AUG). The controller is designed for trajectory tracking problem in existence of external disturbance and parameter variations for pitching angle and net buoyancy of the longitudinal plane of an AUG. The algorithm is designed based on integral sliding mode control and super-twisting sliding mode control. The performance of the proposed controller is compared to original integral sliding mode and original super-twisting algorithm. The simulation results have shown that the proposed controller demonstrates satisfactory performance and also reduces the chattering effect and control effort

Robust nonlinear liquid level control of a coupled-tank system using backstepping integral sliding mode control

This paper presents the formulation of nonlinear robust control that integrates backstepping and integral sliding mode control strategies for controlling liquid level in a two-tank system. In the classical sliding mode control, a discontinuous control law is synthesized to drive the system state to the sliding surface in a finite time and maintain it thereafter on that surface. The technique is naturally suited for the tracking of controlled systems, such as liquid level control inside two-tank system. However, the effects of the discontinuous nature of the control, known as the chattering phenomenon is harmful because it leads to low control accuracy and high wear and tear of moving mechanical parts. The hybrid control preserves the main advantages as it is reduced the chattering effect and provide higher accuracy in realisation of the control system. The performance of the proposed controller is simulated using MATLAB/Simulink software which tested for nominal system, system with external disturbance and system with parameter variation. The performance of proposed controller is compared against the performance of backstepping sliding mode control and integral sliding mode control in terms of chattering reduction and steady state error. The simulation results have shown that the proposed controller has improved the output tracking performance better than the performance backstepping sliding mode control (BSMC) and integral sliding mode (ISMC) with ISMC shows slowest respond. Undesired chattering in sliding surface has been reduced

Initial study of multiple excitation source for electrical resistance tomography in steel pipe application

Tomography is a method of reconstructing the image of an object’s interest within the sensing zone. Electrical resistance tomography (ERT) system operates when using current as an excitation source and output voltage is meas-ured at the detection electrode and the research will result in the changes of elec-tric potential distribution. A lot of researches have been made using ERT to iden-tify a liquid-gas regime in the steel pipe focused on improving image resolution of the regime. However, a common excitation source of ERT used only a single excitation. Thus, this research uses COMSOL Multiphysics as a platform for sim-ulation of multiple excitations of electrical resistance tomography for liquid-gas regime identification in steel pipe. The analysis and performance of new simula-tion which applies multiple excitation sources have been compared with the sin-gle excitation. Besides, the project is limited to 54mm inner diameter of the steel pipe. As a conclusion, 50% of the excitation source can increase the image reso-lution of those regimes especially in the middle of the steel pipe

Liquid level sensing device

The project designed to be implemented to measure the level of molten iron liquid inside a tank. The design is based on a torque-controlled drive where the level of the liquid in the tank is measured using a suspended float. The float is lowered from the disc drilled around its perimeter and a lightweight rope, using torque sensitive electric drive and rotary encoder circuit to produce the pulse that is used to calculate the level of the liquid inside a tank. When the float makes contact with the liquid level surface, the torque reduces and the number of revolutions made by the disc is counted and the level is calculated using an appropriate formula and displayed

Backstepping Integral Super Twisting Sliding Mode Control Algorithm For Autonomous Underwater Glider

The autonomous underwater glider (AUG) demonstrates highly nonlinear and complexity in its dynamic model and also coupled with external underwater environment and disturbance. With limited actuators, the only option that AUG has in facing such environment and disturbances is by using strategies of control algorithm. For this reason, the main objective of this research is to formulate the control law that has the capability in facing the external disturbances and uncertainties due its hydrodynamics coefficients. As a result, a robust and reliable has been designed using back-stepping integral super twisting sliding mode control algorithm (BISTSMC) for nonlinear model of longitudinal plane of an AUG. The BISTSMC was tested for external disturbance and parameter variations. The BISTSMC has been benchmarked its performances with other sliding mode control (SMC) strategies to evaluate the chattering suppression of the controllers. The BISTSMC was benchmarked with integral SMC (ISMC), super twisting SMC (STSMC), integral STSMC (ISTSMC), back-stepping ISMC and back-stepping STSMC. The simulation results have shown that the proposed controller provides the smallest chattering about more than 100 times smaller than ISTSMC, more than 10000 times smaller than backstepping ISMC and backstepping STSMC in nominal, disturbance and parameter variation cases respectively. The steady error of the proposed controller also gives the smallest steady state error of four times smaller than ISTSMC and backstepping ISMC and two times smaller than backstepping STSMC in all cases for pitching angle and 1000 times smaller than ISTSMC and 100 times smaller than backstepping ISMC and backstepping STSMC for excess mass. The proposed controller is a new chattering suppression method which provides the smallest steady state error and chattering has been also suppressed in all cases

Design and Development of an X4-ROV

Remotely operated vehicle (ROV) is an unmanned underwater vehicle (UUV) used for conducting underwater task to replace a human diver in the risky job. X4-ROV is a micro observation class ROV to be used mainly for visual observation of underwater structure or environment by utilizing a high definition web camera. The designed vehicle structure was aims towards portability and maneuverability in attitude motions of roll, pitch, and yaw, and the translational motion forward/reverse/lateral. This work explains the use and modification of an open-source platform (OpenROV) into X4-ROV syste