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Journal of Control Science and Engineering
Volume 2012, Article ID 368503, 10 pages
http://dx.doi.org/10.1155/2012/368503
Research Article

Networked Control System for the Guidance of a Four-Wheel Steering Agricultural Robotic Platform

1São Paulo State University, UNESP Sorocaba, SP, Brazil
2University of São Paulo at São Carlos, São Carlos, SP, Brazil
3Brazilian Agricultural Instrumentation Research Corporation, São Carlos, SP, Brazil

Received 1 December 2011; Revised 2 February 2012; Accepted 9 February 2012

Academic Editor: Yang Shi

Copyright © 2012 Eduardo Paciência Godoy et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A current trend in the agricultural area is the development of mobile robots and autonomous vehicles for precision agriculture (PA). One of the major challenges in the design of these robots is the development of the electronic architecture for the control of the devices. In a joint project among research institutions and a private company in Brazil a multifunctional robotic platform for information acquisition in PA is being designed. This platform has as main characteristics four-wheel propulsion and independent steering, adjustable width, span of 1,80 m in height, diesel engine, hydraulic system, and a CAN-based networked control system (NCS). This paper presents a NCS solution for the platform guidance by the four-wheel hydraulic steering distributed control. The control strategy, centered on the robot manipulators control theory, is based on the difference between the desired and actual position and considering the angular speed of the wheels. The results demonstrate that the NCS was simple and efficient, providing suitable steering performance for the platform guidance. Even though the simplicity of the NCS solution developed, it also overcame some verified control challenges in the robot guidance system design such as the hydraulic system delay, nonlinearities in the steering actuators, and inertia in the steering system due the friction of different terrains.