This chapter reviews a stabilization of underactuated X4-AUV using nonlinear control and optimization technique. Firstly, an overview of underwater vehicles and it categorize are explained. Then, details explanation of AUVs and the problems in controlling AUV systems which fall into the underactuated system with nonholonomic constraints are presented. Backstepping is one of nonlinear control methods and previous research work used backstepping control given in this chapter subsection. Lastly, a particle swarm optimization (PSO) in parameter tuning is explained.
2.2 UNDERWATER VEHICLES
On Earth, water covers more than 70 percent of the earth 's surface and on the year 2000, the National Oceanic and Atmospheric Administration (NOAA) estimated that …show more content…
Mostly those systems fail to satisfy Brockett’s Theorem (Brockett, 1983) i.e., these systems cannot be stabilized to a point with pure smooth (or even continuous) state feedback control. The dynamics of AUVs mostly are highly nonlinear systems, strong coupling, and have uncertainties in hydrodynamics parameters.
Underactuated systems are systems with less number of control inputs than the number of DOFs. Consideration for setting up a system with fewer actuators than DOFs is motivated by several reasons. The main aims to reduce the cost, less actuator will need less energy to operate and it is indirectly reducing the costs of fuel. Besides, it is space-saving and fewer actuators make a structure become lighter. Furthermore, it also increases the reliability of a system in case actuator failures occur. Examples of underactuated systems can be found in but are not limited to, e.g. robotics, aerospace systems, marine systems, flexible systems, mobile systems, and locomotive systems (Spong, 1998; Reyhanoglu et al.,