Camera as Position Sensor for a Ball and Beam Control System

Alejandro Israel Barranco Gutiérrez, Jesús Alberto Sandoval Galarza, Saúl Martínez Díaz


This paper describes a novel strategy to use a digital camera as a position sensor to control a ball and beam system. A linear control law is used to position the ball at the desired location on the beam. The experiments show how this method controls the positioning of the ball in any location on the beam using a camera with a sampling rate of 30 frames per second (fps), and these results are compared with those using an analog resistive sensor with a feedback signal sampled at rate 1000 samples per second. The mechanical characteristics of this ball and beam system are used to simplify the calculation of the ball position using our vision system, and in order to easy camera calibration with respect to the ball and beam system. Our proposal use circularity feature of blobs in a binary image, instead of the classic correlation or Hough transform techniques for ball’s tracking. The main control system is implemented in Simulink with Real Time Workshop (RTW) and the vision processing with OpenCV libraries.


Computer vision, ball and beam system, linear control.

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