Pure-Pursuit Reactive Path Tracking for Nonholonomic Mobile Robots with a 2D Laser Scanner
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Research Article Pure-Pursuit Reactive Path Tracking for Nonholonomic Mobile Robots with a 2D Laser Scanner ´ Morales, Jorge L. Mart´ınez, Mar´ıa A. Mart´ınez, and Anthony Mandow Jesus E.T.S. Ingenieros Industriales, Universidad de M´alaga, 29071 M´alaga, Spain ´ Morales, [email protected] Correspondence should be addressed to Jesus Received 31 July 2008; Revised 5 December 2008; Accepted 30 January 2009 Recommended by Matthijs Spaan Due to its simplicity and efficiency, the pure-pursuit path tracking method has been widely employed for planned navigation of nonholonomic ground vehicles. In this paper, we investigate the application of this technique for reactive tracking of paths that are implicitly defined by perceived environmental features. Goal points are obtained through an efficient interpretation of range data from an onboard 2D laser scanner to follow persons, corridors, and walls. Moreover, this formulation allows that a robotic mission can be composed of a combination of different types of path segments. These techniques have been successfully tested in the tracked mobile robot Auriga-α in an indoor environment. ´ Morales et al. This is an open access article distributed under the Creative Commons Attribution License, Copyright © 2009 Jesus which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction A mobile robot path can be defined as the course that the vehicle has to follow in the environment. It should be useful for carrying out the mobile robot mission, and admissible from the vehicle’s kinematic and dynamic standpoints. Path following is performed by the path tracking controller. Its goal is to autonomously drive the mobile robot along the path by continually generating speed and steering commands that compensate for the tracking errors. These mainly consist of vehicle’s deviations in distance and heading from the path. Both feedback and feedforward control mechanisms are employed for this purpose, with a tradeoff between control effort and control error. Some path tracking methods for ground vehicles are based on nonlinear control theory, such as PredictiveControl [1] or Fuzzy-Control [2]. Alternatively, geometric considerations between the current vehicle pose and the path to follow can provide simpler tracking strategies [3]. A widespread and effective geometric method is the purepursuit algorithm [3]. It calculates a circumference arc that joins the current position of the vehicle and a goal point in the path. This point is chosen at a specified lookahead distance, which is the chord length of this arc. The advantages of this method include the ease of tuning of the lookahead
distance, its computational simplicity, and the absence of derivative terms. Paths for mobile robots can be classified broadly as explicit or implicit. An explicit path is defined in a global frame as a sequence of way-point coordinates that are joined by straight line segments [4] or by adjusting a parametric curve [5]. In this case, tracking er
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