Autonomous and teleoperation control of a mobile robot Ricardo Carelli a , Guillermo Forte b , Luis Canali b , Vicente Mut a, * , Gasto ´n Aragua ´s b , Eduardo Deste ´fanis b a Instituto de Automa ´ tica, Universidad Nacional de San Juan, Argentina b Grupo de Investigaciones en Informa ´ tica para la Ingenierı ´a, F.R. Co ´ rdoba, U.T.N., Argentina Received 23 March 2007; accepted 14 January 2008 Abstract The present work proposes an autonomous tracking control system and a control structure to combine autonomous and teleoperation commands in a bicycle-type mobile robot. This compounded operation renders great flexibility to the control system of the mobile robot. For autonomous operation, a simple tracking controller that includes compensation of the robot dynamics is developed. This tracking control system is proved to be stable in the sense that it asymptotically reaches the tracking objective. Teleoperation with visual access to the robot’s workspace is integrated via a joystick with the autonomous operation of the robot. Simulations and experimental results on a prototype robot show the feasibility and performance of the proposed control system. Ó 2008 Elsevier Ltd. All rights reserved. Keywords: Mobile robots; Trajectory tracking; Teleoperation; Nonlinear systems 1. Introduction Control problems on mobile robot navigation have attracted much attention in the last decade. Some solutions were focused on sensor-based control approaches for inter- active motion in unknown or dynamic environments using radar [1], sonar [2], video [3], optical flow [4,5]. Some authors have delved into parking control or tracking a desired trajectory. The desired robot trajectory is previ- ously planned based on a model of the environment. Diffi- culties in control design are mainly linked to non- holonomic constraints from the kinematics of the mobile robot. Solutions for the tracking problem have been pro- posed in [6–9]. In [6], a Lyapunov asymptotically stable tracking controller is proposed for non-holonomic vehicles, but only kinematics is considered. Besides, it assumes a nonzero reference velocity which prevents using the con- troller for parking. In [7], the concept of virtual vehicle approach is used to design stable tracking controllers based on the kinematics model of wheeled vehicles. A robust solution for tracking control of differentially steered robots is proposed in [8], which uses a simplified dynamic model of the vehicle. The control inputs are the torques from dc drives, which are values difficult to establish. Besides, the paper shows only simulation results. In [9], a controller is proposed to track and park unicycle-type robots. Although saturation on control signals is taken into account, only the kinematics model is considered in the controller design. On the other hand, teleoperation of mobile robots has become an active research line in recent years [10]. In tele- operation, a human operator issues commands to the robot while having perceptive access to the working space. The present work proposes to compound both para- digms – autonomous tracking and teleoperation – applied to a prototype mobile robot that has a kinematics structure commonly found in robots for industrial applications. As regards autonomous tracking, a simple stable tracking con- trol solution has been designed for a bicycle-structure 0957-4158/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.mechatronics.2008.01.002 * Corresponding author. Tel.: +54 264 4213303; fax: +54 264 4213672. E-mail addresses: rcarelli@inaut.unsj.edu.ar (R. Carelli), gforte@scdt. frc.utn.edu.ar (G. Forte), lcanali@scdt.frc.utn.edu.ar (L. Canali), vmut@ inaut.unsj.edu.ar (V. Mut), garaguas@scdt.frc.utn.edu.ar (G. Aragua ´s), edestefanis@scdt.frc.utn.edu.ar (E. Deste ´fanis). Available online at www.sciencedirect.com Mechatronics 18 (2008) 187–194