Precision Position Control Using an RGB Sensor and Linearized Output Variable-Intensity Color Array

Abstract

This thesis presents the design and implementation of a single degree-of-freedom (DOF) position control algorithm, using a red-green-blue (RGB) color sensor and a linearized color array. This work was implemented on a pre-existing magnetic-levitation (maglev) test bed with decoupled controllers for each of the 6 DOFs. The RGB sensor was attached horizontally onto a cantilever beam away from the moving platen and centered over a strip with varying RGB intensity values of the color red. The intensity values that make up the red strip were linearized based upon the response of the sensor as it was moved across the color strip. This linear sensor response was then used to develop a first-order curve-fit to relate position in the y-axis to the sensor output. The functionality of the control algorithm was verified through a series of step responses and continuous motion test runs. The position resolution, in the axis of movement, was demonstrated to be better than 30 µm. Experimental results of both the position response and linearization process are presented herein.