J. Fuentes–Pacheco¹, J. Ruiz–Ascencio*¹, J. M. Rendón–Mancha²

¹ Centro Nacional de Investigación y Desarrollo Tecnológico, Interior Internado Palmira S/N, Col. Palmira, C.P. 62490, Cuernavaca, Morelos, México.

² Universidad Autónoma del Estado de Morelos. Av. Universidad 1001, Col. Chamilpa, C.P. 62209, Cuernavaca, Morelos, México. *josera@cenidet.edu.mx.

ABSTRACT

This paper presents a binocular eye–to–hand visual servoing system that is able to track and grasp a moving object in real time. Linear predictors are employed to estimate the object trajectory in three dimensions and are capable of predicting future positions even if the object is temporarily occluded. For its development we have used a CRS T475 manipulator robot with six degrees of freedom and two fixed cameras in a stereo pair configuration. The system has a client–server architecture and is composed of two main parts: the vision system and the control system. The vision system uses color detection to extract the object from the background and a tracking technique based on search windows and object moments. The control system uses the RobWork library to generate the movement instructions and to send them to a C550 controller by means of the serial port. Experimental results are presented to verify the validity and the efficacy of the proposed visual servoing system.

RESUMEN

En este trabajo se presenta un sistema servo control visual binocular eye–to–hand capaz de seguir y asir un objeto móvil en tiempo real. Se utilizaron predictores lineales para estimar la trayectoria del objeto en tres dimensiones, estos son capaces de predecir futuras posiciones incluso si el objeto es temporalmente ocluido. Para su desarrollo se utiliza un robot manipulador CRS T475 de seis grados de libertad y dos cámaras fijas con una configuración de par estéreo. El sistema tiene una arquitectura cliente–servidor y se compone de dos partes principales: el sistema de visión y el sistema de control. El sistema de visión utiliza una detección por color para extraer el objeto del fondo y una técnica de seguimiento basada en ventanas de búsqueda y momentos del objeto. El sistema de control emplea la librería RobWork para generar las instrucciones de movimiento y enviarlas a un controlador C550 por medio del puerto serial. Se presentan resultados experimentales para verificar la validez y eficacia del sistema servo control visual.

Palabras clave: Predicción lineal, servo control visual, seguimiento, visión estéreo, calibración de cámaras.

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Acknowledgments

This paper has been made possible thanks to the generous support from the following institutions which we are pleased to acknowledge: CONACYT (Consejo Nacional de Ciencia y Tecnología) and CENIDET (Centro Nacional de Investigación y Desarrollo Tecnológico).

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