# Designing A Control System For Underwater Gliders

1311 WordsApr 24, 20156 Pages

Abstract:
This project deals with the designing a control system for Underwater Gliders. Among the Autonomous underwater vehicles, the most efficient ones are the underwater gliders as they are driven by buoyancy and they spend much of their flight time in stable, steady motion. This project deals with the modelling the control system for efficiently maneuvering the glider using the equations of motion for the underwater glider. After modelling the system it is simulated with various inputs such as step, impulse and sine inputs. Then the system is checked for its stability by varying the parameters related to the glider such as the mass of the actuator, buoyancy. The Pitch and translation along the Z - axis are the main degrees of freedom*…show more content…* These parameters are to be controlled for attaining a steady state motion. For this a control system needs to be designed which provides feedback in response to the errors which are present in the state of motion. [1]
Mathematical Modelling of the System:
DC Servo Motor:
DC Servo Motor
Glider Modelling: The glider is considered to be a rigid body of mass mv. Under conditions of neutral buoyancy the vehicle displaces the fluid having mass similar to that of the vehicle. Excess mass is defined as m̃= mv – m. The mass m̃ is modified by an inflatable bladder, thus changing the value of m by changing the displaced volume. For creating a dynamic model of the vehicle a reference frame is defined. This is body-fixed, orthonormal reference frame which is centered at the geometric center of the vehicle and it is represented by unit vectors b1, b2 and b3. Now another orthonormal reference frame is defined which is denoted by the unit vectors i1, i2, and i3, which are fixed in inertial space such that i3 is aligned with the force due to gravity. The relative orientation of these two reference frames is given by the proper rotation matrix RIB, which maps the free vectors from the body frame to the inertial frame. RIB in terms of conventional Euler angles (roll angle, pitch angle, and yaw angle). The location of the body frame with respect to the inertial frame is given by