Juan Marcos Toibero

Switching Control of Mobile Robots for Autonomous Navigation in Unknown Environments

This paper presents a switching controller for positioning a unicycle-like mobile robot at a desired point with final orientation avoiding obstacles in completely unknown environments. To this aim two complementary algorithms are included: the first decides whether to avoid an obstacle around its right or left side, and the second is intended to detect when an obstacle was successfully avoided. The obstacle avoidance is performed using a laser-based reactive contour-following controller. The switching controllers include the stability analysis at the switching times, using common and multiple Lyapunov functions. Finally, experimental results in a typical unicycle-like mobile robot show the performance of the proposed hybrid control system.

Stable contour-following control of wheeled mobile robots

This paper presents a continuous wall-following controller for wheeled mobile robots based on odometry and distance information. The reference for this controller is the desired distance from the robot to the wall and allows the robot to follow straight wall contour as well as smoothly varying wall contours by including the curvature of the wall into the controller. The asymptotic stability of the control system is proved using a Lyapunov analysis. The controller is designed so as to avoid saturation of the angular velocity command to the robot. A novel switching scheme is also proposed that allows the robot to follow discontinuous contours allowing the robotic system to deal with typical problems of continuous wall-following controllers such as open corners and possible collisions. This strategy overcomes these instances by switching between dedicated behavior-based controllers. The stability of the switching control system is discussed by considering Lyapunov concepts. The proposed control systems are verified experimentally in laboratory and office environments to show the feasibility and good performance of the control algorithms.

Including dissolved oxygen dynamics into the Bt δ-endotoxins production process model and its application to process control

This paper proposes a model to characterize the Dissolved Oxygen Dynamics (DO) for the Bacillus thuringiensis (Bt) δ-endotoxins production process. The objective of this work is to include this dynamics into a phenomenological model of the process in order to facilitate the biomass estimation from the knowledge of oxygen consumption; and for control purposes, by allowing the addition of a new control variable in order to favorably influence the bioprocess evolution. The mentioned DO model is based on first principles and parameter estimation and model verification are supported by real experimental data. Finally, a control strategy is designed based on this model with its corresponding asymptotic stability and robustness analysis.

Ultra Wide-Band Localization and SLAM: A Comparative Study for Mobile Robot Navigation

In this work, a comparative study between an Ultra Wide-Band (UWB) localization system and a Simultaneous Localization and Mapping (SLAM) algorithm is presented. Due to its high bandwidth and short pulses length, UWB potentially allows great accuracy in range measurements based on Time of Arrival (TOA) estimation. SLAM algorithms recursively estimates the map of an environment and the pose (position and orientation) of a mobile robot within that environment. The comparative study presented here involves the performance analysis of implementing in parallel an UWB localization based system and a SLAM algorithm on a mobile robot navigating within an environment. Real time results as well as error analysis are also shown in this work.

Switched Control to Robot-Human Bilateral Interaction for Guiding People

This paper presents a switched control strategy to interpret and design a human-robot bilateral interaction when a human follows a non-holonomic mobile robot at a desired distance while the robot is already following a known path. Furthermore, it proposes and experimentally validates a model that mathematically describes the human behavior when performing the specific task of tracking a mobile robot. This model is useful for the purposes of the control system design and its associated stability analysis. A switched system is proposed to model the complete human-robot behavior. The switching strategy is based on the human-robot relative position and on the human intention to follow the robot. Control errors are defined in terms of human to robot and robot to path instantaneous distances. Stability analyses for the individual controllers, as well as for the complete switching system, are provided by considering Lyapunov theory. Real human-robot interaction experiments show the good performance of the proposed control strategy.

Hybrid Collaborative Stereo Vision System for Mobile Robots Formation

This paper presents the use of a hybrid collaborative stereo vision system (3D-distributed visual sensing using different kinds of vision cameras) for the autonomous navigation of a wheeled robot team. It is proposed a triangulation-based method for the 3D-posture computation of an unknown object by considering the collaborative hybrid stereo vision system, and this way to steer the robot team to a desired position relative to such object while maintaining a desired robot formation. Experimental results with real mobile robots are included to validate the proposed vision system.

Hybrid Formation Control for Non-Holonomic Wheeled Mobile Robots

This paper presents a hybrid formation controller approach for non-holonomic mobile robots. This approach is based on the stable switching between a leader-following formation controller and an orientation controller. The switching attempts to maintain low values of formation errors during specific leader movements that otherwise will produce a significant increment on such errors. Experimental results on commercial unicycle-like mobile robots are provided to show the feasibility and performance of the proposed control strategy.

Switching control signal for bilateral tele-operation of a mobile manipulator

This paper presents both the design and the implementation of a bilateral teleoperation system for a mobile manipulator, allowing a human operator to perform complex tasks in remote environments. Two teleoperation operation modes are proposed: the locomotion mode (mobile manipulator) and the manipulation mode (robotic arm). The human operator can select the modes through the switch located on a haptic device. The user receives visual and force feedback from the remote site, and it sends velocity or position commands to the slave, according to the operation mode. Furthermore, the redundancy control of the system for obstacle avoidance is considered by the mobile platform, and the singular configuration prevention through the systems manipulability control. Finally, experimental results are reported to verify the performance of the proposed system.

Monte Carlo uncertainty maps-based for mobile robot autonomous SLAM navigation

This paper presents an uncertainty maps construction method of an environment by a mobile robot when executing a SLAM (Simultaneous Localization and Mapping) algorithm. The SLAM algorithm is implemented on a Extended Kalman Filter (EKF) and extracts corners (convex and concave) and lines (associated with walls) from the surrounding environment. A navigation approach directs the robot motion to the regions of the environment with the higher uncertainty. The uncertainty of a region is specified by a probability characterization computed at the corresponding representative points. These points are obtained by a Monte Carlo experiment and their probability is estimated by the sum of Gaussians method, avoiding the timeconsuming map-gridding procedure. The mobile robot has a contour-following controller implemented on it to drive the robot to the uncertainty points. SLAM real time experiments within real environments are also included in this work.

Stable switching contour-following controller for wheeled mobile robots

In this paper a switching controller for mobile robots is presented that allows the contour-following of objects the size of which is at least comparable to that of the robot. The controller uses the information from distance sensors and is based on a wall-following controller described in the paper. The stability of the overall switching system is proved by using a common Lyapunov function. Experimental results in a Pioneer III unicycle-like mobile robot are provided to show the feasibility of the proposed control strategy