Continuous adaptive sliding-mode control scheme for an autonomous underwater vehicle with region-based approach

Set point method has been typically used for trajectory tracking of Autonomous Underwater Vehicle (AUV). However, this method has several limitations. In this regard, region based method has been applied in trajectory tracking of AUV in order to solve the limitations of set point method. The main idea behind the region-based method is the tracking target of an AUV set as a region, so that the AUV will maintain its position under weak ocean current. This method uses lower energy compared to set point method because the AUV will not turn on its thrusters as long as it maintains its position within the region. Realistically, there is also strong current that can drift vehicle away from the required region. The purpose of the thesis is to develop a robust controller with region-based method. Robust control enables an AUV to reject the disturbance and re-enter the region even under the influence of external disturbance. Based on the literature review, adaptive sliding mode control was chosen as the proposed controller in this study. Sliding mode control is known for its insensitivity towards uncertainty and external disturbance. Adaptive component was introduced to replace switching component. This substitute enables AUV to reject external disturbance better compared to conventional sliding mode control. The stability of the proposed controller was analyzed using Lyapunov function. The energy consumption of region based method was compared with the set point tracking method. It has been shown from this study that the energy consumption for region-based method is indeed lower than set point method. The effectiveness of the proposed controller was compared with adaptive controller using simulation under the influence of ocean current. Underwater vehicle model used in the simulation was Omni Directional Intelligent Navigator (ODIN). It has been proven that the proposed controller performed better compared to adaptive controller. The proposed controller had managed to handle ocean current and re-enter the region

Fuzzy sliding mode with region tracking control for autonomous underwater vehicle

This paper presents fuzzy sliding mode control with region tracking control for a single autonomous underwater vehicle. The vehicle is needed to track a certain moving region whilst under the influence of wave current. The fuzzy logic is used to tune the gain and to reduce the effect of chattering effect, the signum function is replaced by saturation function. Simulation result is presented to demonstrate the performance of the proposed tracking control of the AUV

Comparison of two type of fuzzy sliding mode with region tracking control for autonomous underwater vehicle

This paper presented two type of fuzzy sliding mode control with region tracking control for a single autonomous underwater vehicle. The vehicle is needed to track a certain moving region whilst under the influence of wave current. The first fuzzy logic proposed is used to tune the gain and to reduce the chattering effect; the signum function is replaced by saturation function. In second fuzzy type sliding mode controller, the switching term or reaching law is modeled using fuzzy logic. Simulation result is presented to demonstrate the performance of the two proposed tracking control of the AUV and the performance is compared

Adaptive tracking control scheme for an autonomous underwater vehicle subject to a union of boundaries

999-1005Present study presents a novel region boundary-based tracking control for an Autonomous Underwater Vehicle (AUV). The control objective is to track a moving target formed by the union of all boundaries. In this case, multiplicative potential energy function is used to unite all the boundaries and various shapes can be created using this function. It is interesting to note that the AUV will be placed at a specific position on the dynamic region boundaries. A Lyapunov-like function is presented for stability analysis of the AUV. Simulation studies will be performed to illustrate the effectiveness of the proposed controller. </span

Sliding mode fuzzy controller for autonomous underwater vehicle under deterministic disturbances

The main problem for autonomous underwater vehicle (AUV) is not only how to make a stable underwater vehicle but also how to keep the AUV form its desire trajectory. Some perturbations such as wind, waves, and ocean currents are the crucial factors to disturb the AUV. Those will move AUV's position from for the desired track. To cope with this problem, sliding mode control (SMC) is used to make a robust AUV under a range of ocean disturbances. Moreover, the chattering effect which is produced by SMC will be overcome by fuzzy logic control (FLC). A simulation is presented to analyse the effectiveness of proposed control under some deterministic condition. However, the results show that the movement of AUV under high value of disturbances cannot be solved by the proposed control