Edgar A. Martínez-García

Crowding and guiding groups of humans by teams of mobile robots

This article introduces a general description of a multi-robot system (MRS) architecture aimed to provide guidance for a group of humans. At a first approach, only the strategy and architecture framework are described, further than the ethological and human factors involved in human-robot interaction. The paper encompasses a special strategy to conduct and crowd multiple people. Such strategy includes a methodology to localize multi-human; a MRS architecture design; and a control for people trajectory and a robots motion planner. A key-problem in the implementation of the system is that, there is no signal of any type for accomplishing guidance. In addition, some experimental and simulation results are presented, which exhibits the effectiveness of the proposed architecture, and the social force model adapted in a manner to simulate behavior of groups of people.

Vision-based Reactive Autonomous Navigation with Obstacle Avoidance: Towards a non-invasive and cautious exploration of marine habitat

We present a visual based approach for reactive autonomous navigation of an underwater vehicle. In particular, we are interested in the exploration and continuous monitoring of coral reefs in order to diagnose disease or physical damage. An autonomous underwater vehicle needs to decide in real time the best route while avoiding collisions with fragile marine life and structure. We have opted to use only visual information as input. We have improved the Simple Linear Iterative Cluster algorithm which, together with a simple nearest neighbor classifier, robustly segment and classify objects from water in a fast and efficient way, even in poor visibility conditions. From the resulting classification and the current robots direction and orientation, the next possible free-collision route can be estimated. This is achieved by grouping together neighboring water superpixels (considered as “regions of interest”). Finally, we use a model-free robust control scheme that allows the robot to autonomously navigate through the free-collision routes obtained in the first step. The experimental results, both in simulations and in practice, show the effectiveness of the proposed navigation system.

A Fast Floor Segmentation Algorithm for Visual-Based Robot Navigation

We present a novel technique that robustly segments free-space for robot navigation purposes. In particular, we are interested in a reactive visual navigation, in which the rapid and accurate detection of free space where the robot can navigate is crucial. Contrary to existing methods that use multiple cameras in different configurations, we use a downward-facing monocular camera to search for free space in a large and complicated room environment. The proposed approach combines two techniques. First, we apply the Simple Linear Iterative Clustering super-pixel algorithm to the input images. Then, by relying on particular characteristics of floor superpixels, we use a simple classification method based on a normalized SSD similarity measure to group together those superpixels that belongs to the floor (considered as free space). The method intermittently examines low resolution images (80 × 60) in the CIE Lab color model. Experimental results show that our segmentation approach is robust, even in the presence of severe specular reflections and allows for real-time navigation.

Exponential fields formulation for WMR navigation

In this manuscript, an autonomous navigation algorithm for wheeled mobile robots WMR operating in dynamic environments indoors or structured outdoors is formulated. The planning scheme is of critical importance for autonomous navigational tasks in complex dynamic environments. In fast dynamic environments, path planning needs algorithms able to sense simultaneously a diversity of obstacles, and use such sensory information to improve real-time navigation control, while moving towards a desired goal destination. The framework tackles 4 issues. 1 Reformulation of the Social Force Model SFM adapted to WMR; 2 the cohesion of a general inertial scheme to represents motion in any coordinate system; 3 control of actuators rotational speed as a general model regardless kinematic restrictions; 4 assuming detection of features obstacles/goals, adaptive numeric weights are formulated to affect navigational exponential components. Simulation and experimental outdoors results are presented to show the feasibility of the proposed framework.

Dead-reckoning inverse and direct kinematic solution of a 4W independent driven rover

We tackle the problem of trajectory control of a four-wheel driven skid-steering (4WDSS) robotic platform with asynchronous wheels velocity. A practical mathematical formulation for solving inverse and direct kinematics is provided. This approach also includes the formulation and implementation of a home made arrange of accelerometers to infer robot displacements in global coordinates system. Although we provide a direct kinematics solution, we further establish an inverse kinematics formulation using four parameters to exert trajectory control, namely instantaneous linear velocity, angular velocity, and robot Z-turning axes. The formulation for robot angular velocity is given differently from other research approaches, where it is stated in terms of the robots geometry, which directly impacts the robots swift capability. Trajectory control is yielded by controlling the location of the robot turning Z-axis with respect to the instantaneous center of rotation by direct control of the wheels speeds.

Trajectory control for groups of humans by deploying a team of mobile robots

In this paper a multirobot system (MRS) trajectory control for conducting a group of humans is proposed. Its architecture, implementation and the strategy to conduct people by a team of robots is discussed, as well as the robots motion planning methodology is being encompassed. Some experimental results on people localization by a vision system are also introduced, which exhibit its usage as sensory information for generation of people trajectory control. A social model to simulate humans motion is also included in this investigation as means to prove the mechanism of guidance and crowd dynamics by the team of robots, where such motion control is based on intelligent changes of position and speed

Multi-robot communication architecture for human guiding

Abstract In this paper the architecture of a multi-robot communication system is described as a means of accomplishment of indoors human-guidance tasks. Communication in multi-robots is a critical issue both for localization in the formation and for sharing distributed sensory information. Both problems can be overcome as a cooperative framework, whereby the communication system is the key issue, and its architecture design as well as its implementation are presented in detail.

A multi-configuration kinematic model for active drive/steer four-wheel robot structures

In this study, a general kinematic control law for automatic multi-configuration of four-wheel active drive/steer robots is proposed. This work presents models of four-wheel drive and steer (4WD4S) robotic systems with all-wheel active drive and steer simultaneously. This kinematic model comprises 12 degrees of freedom (DOFs) in a special design of a mechanical structure for each wheel. The control variables are wheel yaw, wheel roll, and suspension pitch by active/passive damper systems. The pitch angle implies that a wheels contact point translates its position over time collinear with the robots lateral sides. The formulation proposed involves the inference of the virtual z-turn axis (robots body rotation axis) to be used in the control of the robots posture by at least two acceleration measurements local to the robots body. The z-turn axis is deduced through a set of linear equations in which the number of equations is equal to the number of acceleration measurements. This research provides two main models for stability conditions. Finally, the results are sustained by different numerical simulations that validate the system with different locomotion configurations.

Multi-legged robot dynamics navigation model with optical flow

Purpose – The purpose of this paper is to establish analytical and numerical solutions of a navigational law to estimate displacements of hyper-static multi-legged mobile robots, which combines: monocular vision (optical flow of regional invariants) and legs dynamics. Design/methodology/approach – In this study the authors propose a Euler-Lagrange equation that control legs’ joints to control robots displacements. Robots rotation and translational velocities are feedback by motion features of visual invariant descriptors. A general analytical solution of a derivative navigation law is proposed for hyper-static robots. The feedback is formulated with the local speed rate obtained from optical flow of visual regional invariants. The proposed formulation includes a data association algorithm aimed to correlate visual invariant descriptors detected in sequential images through monocular vision. The navigation law is constrained by a set of three kinematic equilibrium conditions for navigational scenarios: c...

Telepresence by deploying an avatar robot with brain-robot interfacing

This manuscript describes in detail the development of an avatar robot for human companion tasks. The mobile robot embodies a remote human to have communications with other human while walking in close proximity to the mobile robot. The robot takes the role of a physical interface to deploy mobility, sensors and telepresence with personification throughout some behaviours of the remote human. Behaviours are conveyed through commands from a mouse/joystick and a EEG-based BRI. We discuss the aim of this work, as well as the tele-system architecture. Both the mobile robot featuring avatar capabilities, and the BRI are discussed. The system concept is also described and we report implementations and experimental results.