# Design and Implementation of a Six-Degrees-of-Freedom Underwater Remotely Operated Vehicle
## 1 Introduction  
The water surface covers almost three-fourths of our planet's total surface area, providing humans with a variety of mineral and natural resources. With terrestrial reserves being depleted, a growing focus has arisen on exploring the seabed for resources such as gas, oil, and minerals. However, traditional manned systems and human divers are limited in investigating vast and often hazardous underwater environments. To overcome these challenges, remotely operated vehicles (ROVs) have gained popularity among governmental agencies and commercial companies as they can undertake complex missions without risking human lives [1]. ROVs are often equipped with cameras, sensors, and manipulator's arms, allowing operators to remotely navigate and interact with the underwater environment [2; 3; 4; 5; 6]. They are operated from a surface vessel or a control room onshore, using a tether that provides power and communication between the vehicle and the operator. ROVs have revolutionized how we explore the ocean, allowing us to gather data and samples, perform maintenance and repairs on underwater infrastructure, and conduct scientific research in inaccessible areas [7; 8; 9; 10]. [PERSON] et al. [11] developed a twin-controller approach using Matlab to regulate the behavior of underwater ROVs. The controller design comprises proportional-integral-derivative (PID) to tune the adaptive gains of the aquatic system and model reference adaptive control (MRAC) to mitigate the dynamic system's disturbance. [PERSON] et al. [12] proposed a depth control strategy that combines fuzzy PID and dynamic compensation. Using ANSYS, the hydrodynamics analysis of ROV was conducted to find out the relationship between the resistance of water and moving velocity in the heave direction. The depth control can vary by 3 cm, which is practical for the reactor pool. [PERSON] et al. [13] developed a small-sized ROV for shipwoks with a variable storing moment by rotating the wing in the vehicle's plane. The ROV had four horizontal thrusters to increase the range of maneuverability. Furthermore, the ROV was enhanced with a lithium battery to reduce the tether's weight and return to the coast in case of emergency or damage to the cable. [PERSON] et al. [14] designed a prototype platform to test and validate new technologies for marine operations. The designed ROV was equipped with advanced 3D visual displays, an easy pilot interface, voice control navigation, and low-level controllers with an autotuning system. The position of a fully actuated underwater ROV with a manipulator was stabilized by [PERSON] et al. [9]. They applied the proposed control algorithm on an eight degrees-of-freedom (DOF) ROV to control the erratic deviations. The simulations proved that the designed ROV could effectively reach the desired position. Other researchers assessed different control methods using neural networks, demonstrating their benefits, shortcomings, and applications [15; 16]. [PERSON] and [PERSON] [17] developed an ROV navigation system through pre-programmed controllers to control the speed. [PERSON] et al. [18] designed an adaptive control mechanism to ensure a 6-DOF ROV follows the desired route. [PERSON] and [PERSON] [19] proposed a hybrid PID controller for the dynamic orientation of ROVs to ensure the accurate execution of tasks near underwater structures. Despite the efforts of previous researchers to enhance the performance of ROVs, little attention has been paid to integrating the various phases of design and fabrication. Thus, the main objective of this study is to develop an entire framework that considers the design, manufacturing, and assembling of a portable ROV system. Furthermore, a coating technique of track width in the printed circuit board (PCB) is presented to reduce the size of the electrical enclosure and, consequently, the vehicle's size. Subsequently, an image processing technique is developed to enhance the ROV's capabilities for performing various tasks in underwater environments.