Generic Solution for Generating Towing Tank Carriage Linear Speed Profile Using Stepper Motor

Abstract

Towing tanks are widely used in measuring of hydrodynamic coefficients and study dynamics of marine vehicles at different operating conditions of motion and different geometry characteristics. In this paper, two stepper motors have been used to drive a towing tank carriage and Pulse Width Modulation (PWM) technique is used to control the speed of the towing carriage according to the speed profile calculated in advance depending on the required operating conditions of the test model. AVR microcontroller has been used to linearly control the speed of the stepper motors in three phases, accelerating from zero to its steady state speed, steady state speed and decelerating until stop. The proposed work makes any required speed profile easy to be obtained and fulfilled in real time, such as the profile needed for a single long acceleration phase throughout the most of the length of tank which is needed in the experimental work for added inertia measurement purpose. A general case to reach an assigned constant speed for hull drag measurements with two different phases of acceleration and deceleration is introduced.