3 research outputs found
Variable Gain Super Twisting Sliding Mode Control (VGSTW) application in longitudinal plane of Autonomous Underwater Glider (AUG)
This paper presents a robust control design using variable gain super twisting sliding mode control application in Autonomous Underwater Glider (AUG). AUGs are known as underactuated systems and very nonlinear in nature make difficult to control. The controller is designed for longitudinal plane of an AUG that tracks the pitching angle and net buoyancy of a ballast pump for nominal system, system in existence of external disturbance and parameter variations in hydrodynamic coefficients. The Lyapunov stability theorem has proved that the proposed control law is satisfied the stability sufficient condition. The simulation results have shown that the proposed controller has improved the transient response, reduced steady error and chattering effects in control input and sliding surface in all cases
Variable Gain Super Twisting Sliding Mode Control (VGSTW) application in longitudinal plane of Autonomous Underwater Glider (AUG)
904-913This paper presents a robust control design using variable gain super twisting sliding mode control application in
Autonomous Underwater Glider (AUG). AUGs are known as underactuated systems and very nonlinear in nature make
difficult to control. The controller is designed for longitudinal plane of an AUG that tracks the pitching angle and net
buoyancy of a ballast pump for nominal system, system in existence of external disturbance and parameter variations in
hydrodynamic coefficients. The Lyapunov stability theorem has proved that the proposed control law is satisfied the
stability sufficient condition. The simulation results have shown that the proposed controller has improved the transient
response, reduced steady error and chattering effects in control input and sliding surface in all cases
A GAIN-SCHEDULED CONTROL SCHEME FOR IMPROVED MANEUVERABILITY AND POWER EFFICIENCY OF UNDERWATER GLIDERS
Underwater gliders are a relatively new type of low-power, long duration underwater
vehicle that use changes in buoyancy to propel themselves forward. They are widely
used today for oceanographic research, and a number of theoretical control schemes
have been derived over the years. However, despite their nonlinear dynamics that
evolve as a function of their environment and operating conditions, most fielded
gliders use linear control methods, such as static-gain proportional-integral (PI) or
proportional-integral-derivative (PID) compensators for motion control, which can
significantly limit vehicle performance.
This thesis develops an alternative approach to underwater glider control that employs
control system gain-scheduling to improve vehicle performance and efficiency over a
wider range of operating conditions as compared to static or fixed-gain approaches. The
primary contribution of this thesis is the development of a practical gain-scheduling
procedure using linearized models of the decoupled pitch and yaw dynamics of the
vehicle. This methodology improves on the current fixed-gain topologies used on
fielded gliders today, while being straightforward and cost-effective to implement.
In this thesis, the development of a nonlinear dynamical model of a Slocum glider using
computer-aided design (CAD) and computational fluid dynamics (CFD) simulations
was also carried out to support the high-fidelity characterization of the controller
topologies. A nonlinear numerical simulation of the Slocum glider was developed in Matlab and was used to assess the performance improvements and the increased
robustness of the gain-scheduled PID method to a standard fixed-gain PID approach