Stability analysis of a small scale remotely operated underwater glider

The conventional process of maintaining underwater depth level for Unmanned Underwater Vehicles (UUVs) requires an operator to have a high skill and experience. Therefore, it is an important assessment to develop an automatic control scheme for underwater depth level control system and fabricate an underwater vehicle’s prototype body as a test-bed to implement and study the performance of control scheme. Hence, the purposes of this research are to design, model and fabricate a prototype body of a Remotely Operated underwater Glider (ROG) and analyze stability equilibrium of the new glider design. This research also attempts to develop a programmable ON/OFF control scheme for the underwater depth level control system and study the performance of the control scheme by experimental verification and trials. The ROG is modelled based on the SLOCUM glider and Seaglider designs using SolidWork and MAXSURF HYDROMAX is employed to calculate the stability equilibrium. The collected real time data are analyzed using the MATLAB System Identification ToolboxTM to verify the ROG’s net weight-depth system. As a conclusion, the ROG has a cylindrical body shape and the stability calculation shows that the ROG is at stable equilibrium state when heeling from 0

Chattering Analysis of an Optimized Sliding Mode Controller for an Electro-Hydraulic Actuator System

Wear and tear are usually caused by various factors, which reduce the life span of a mechanical part. In the control engineering of an Electrohydraulic actuator system, the wear and tear can be caused by the system or the controller itself. This article examines the chattering effect that occurs during the sliding mode controller (SMC) design, and its effect on the nonlinear electrohydraulic actuator (EHA) system. To examine the chattering phenomenon, signum function is first applied on the switching function of the SMC. Then, parameters of the controller are obtained using single objective particle swarm optimization (PSO) method. These parameters are then applied to the switching function with hyperbolic tangent function. Lastly, the performance of both functions is analysed and compared based on graph and numerical data. From the output data, chattering phenomenon generated on the signum function is greatly eliminated by using hyperbolic tangent function

Improved Third Order PID Sliding Mode Controller for Electrohydraulic Actuator Tracking Control

An electrohydraulic actuator (EHA) system is a combination of hydraulic systems and electrical systems which can produce a rapid response, high power-to-weight ratio, and large stiffness. Nevertheless, the EHA system has nonlinear behaviors and modeling uncertainties such as frictions, internal and external leakages, and parametric uncertainties, which lead to significant challenges in controller design for trajectory tracking. Therefore, this paper presents the design of an intelligent adaptive sliding mode proportional integral and derivative (SMCPID) controller, which is the main contribution toward the development of effective control on a third-order model of a double-acting EHA system for trajectory tracking, which significantly reduces chattering under noise disturbance. The sliding mode controller (SMC) is created by utilizing the exponential rule and the Lyapunov theorem to ensure closed-loop stability. The chattering in the SMC controller has been significantly decreased by substituting the modified sigmoid function for the signum function. Particle swarm optimization (PSO) was used to lower the total of absolute errors to adjust the controller. In order to demonstrate the efficacy of the SMCPID controller, the results for trajectory tracking and noise disturbance rejection were compared to those obtained using the proportional integral and derivative (PID), the proportional and derivative (PD), and the sliding mode proportional and derivative (SMCPD) controllers, respectively. In conclusion, the results of the extensive research given have indicated that the SMCPID controller outperforms the PD, PID, and SMCPD controllers in terms of overall performance.

Depth level control system using peripheral interface controller for underwater vehicle

This research explained on a design and development of an Automatic Depth Control System for underwater vehicle. Definition of underwater vehicle is a robotic sub-sea that is a part of the emerging field of autonomous and unmanned vehicles. This project shows the implementation’s development of an Automatic Depth Control System on a test prototyping vehicle especially involved small-scale and low cost sub-sea robots. The Automatic Depth Control System assembled with mechanical system and module of electronic system for development of a controller

Design of a body with depth control system for an underwater glider

This paper describes a design development of an underwater glider which includes the body design, controller design and the sensor integration. The underwater glider is used for deep water to observe large areas with minimal use of energy and move through the water by changing the body weight. The glider contained a cylindrical body attached with two wings and a fix tail. The controller has been designed to use a comparator circuit integrate with a pressure sensor to control the depth level. The pressure sensor mounted on the glider used to sense the underwater pressure. For the beginning, this underwater glider is limited to a depth of 0-10 meters

The Effects Of Weightage Values With Two Objective Functions In iPSO For Electro-Hydraulic Actuator System

In this paper, the Proportional-Integral-Derivative (PID) controller with improved Particle Swarm Optimization (iPSO) algorithm is proposed for the positioning control of nonlinear Electro-Hydraulic Actuator (EHA) system. PID controller is chosen to control the EHA system due to its popularity in industrial applications. The PID controller parameters will be tuned by using the iPSO algorithm to get the lowest overshoot percentage and steady-state error. The conventional PSO algorithm has only one objective function to get the optimum parameters. However, this is not enough to increase the control performance of the EHA system. Therefore, an improved Particle Swarm Optimization (iPSO) that includes the mean error and overshoot percentage as the two objective functions is proposed in this paper. The most popular method in PSO that included two objective functions is Linear Weight Summation (LWS). In this method, the two objective functions are combined with certain weightage into one equation to give the best control performance. This paper focuses on determining the suitable weightage between these two objective functions so that the EHA system can produce the best control performance with less overshoot and less error. Overshoot percentage and steady-state error are used to indicate the best control performance. The results showed that EHA system can perform better by using suitable weightage between the mean error and overshoot percentage