An adaptive scheme for wheelchair navigation collaborative control

In this paper we propose a system where machine and human cooperate at every situation via a reactive emergent behavior, so that the person is always in charge of his/her own motion. Our approach relies on locally evaluating the performance of the human and the wheelchair for each given situation. Then, both their motion commands are weighted according to those efficiencies and combined in a reactive way. This approach benefits from the advantages of typical reactive behaviors to combine different sources of information in a simple, seamless way into an emergent trajectory.Peer ReviewedPostprint (author’s final draft

Grid-based localization and local mapping with moving object detection and tracking

International audienceWe present a real-time algorithm for simultaneous localization and local mapping (local SLAM) with detection and tracking of moving objects (DATMO) in dynamic outdoor environments from a moving vehicle equipped with a laser scanner, short-range radars and odometry. To correct the vehicle odometry we introduce a new fast implementation of incremental scan matching method that can work reliably in dynamic outdoor environments. After obtaining a good vehicle localization, the map surrounding of the vehicle is updated incrementally and moving objects are detected without a priori knowledge of the targets. Detected moving objects are finally tracked by a Multiple Hypothesis Tracker (MHT) coupled with an adaptive Interacting Multiple Model (IMM) filter. The experimental results on datasets collected from different scenarios such as: urban streets, country roads and highways demonstrate the efficiency of the proposed algorithm

Navigating a robotic wheelchair in a railway station during rush hour

In this paper we describe the hardware design, the control and navigation system, and our preliminary experiments with the robotic wheelchair MAid (Mobility Aid for Elderly and Disabled People). MAid's general task is to transport people with severely impaired motion skills such as, for example, paraplegia, multiple sclerosis, poliomyelitis, or muscular dystrophy. Following the advice of disabled people and physicians we did not set out to re-invent and re-develop the set of standard skills of so-called intelligent wheelchairs, such as FollowWalZ, FollowCorridor, PassDoorway which are commonly described in the literature. These maneuvers do not always require fine motion control and disabled people, in spite of their disability, are often well capable of navigating their wheelchair along a corridor and actually eager to do it. In our work we focused instead on maneuvers which are very burdensome because they take a long time and require extreme attention. One of these functions is deliberative locomotion in rapidly changing, large-scale environments, such as shopping malls, entry halls of theaters, and concourses bf airports or railway stations, where tens or hundreds of people and objects are moving around. This function was not only acknowledged as being very useful but also very entertaining, because MAid often had to work very hard to find its way through a crowd of people. MAid's performance was tested in the central station of Ulm during rush-hour, and in the exhibition halls of the Hannover Messe '98, the biggest industrial fair worldwide. Altogether, MAid has survived more than 36 hours of testing in public, crowded environments with heavy passenger traffic. To our knowledge this is the first system among robotic wheelchairs and mobile robots to have achieved a similar performance.

Development of an intelligent wheelchair 3D simulator/visualizer

Tese de mestrado integrado. Engenharia Informática e Computação. Universidade do Porto. Faculdade de Engenharia. 201

Smooth and Collision-Free Navigation for Multiple Mobile Robots and Video Game Characters

The navigation of multiple mobile robots or virtual agents through environments containing static and dynamic obstacles to specified goal locations is an important problem in mobile robotics, many video games, and simulated environments. Moreover, technological advances in mobile robot hardware and video games consoles have allowed increasing numbers of mobile robots or virtual agents to navigate shared environments simultaneously. However, coordinating the navigation of large groups of mobile robots or virtual agents remains a difficult task. Kinematic and dynamic constraints and the effects of sensor and actuator uncertainty exaggerate the challenge of navigating multiple physical mobile robots, and video games players demand plausible motion and an ever increasing visual fidelity of virtual agents without sacrificing frame rate. We present new methods for navigating multiple mobile robots or virtual agents through shared environments, each using formulations based on velocity obstacles. These include algorithms that allow navigation through environments in two-dimensional or three-dimensional workspaces containing both static and dynamic obstacles without collisions or oscillations. Each mobile robot or virtual agent senses its surroundings and acts independently, without central coordination or inter-communication with its neighbors, implicitly assuming the neighbors use the same navigation strategy based on the notion of reciprocity. We use the position, velocity, and physical extent of neighboring mobile robots or virtual agents to compute their future trajectories to avoid collisions locally and show that, in principle, it is possible to theoretically guarantee that the motion of each mobile robot or virtual agent is smooth. Moreover, we demonstrate direct, collision-free, and oscillation-free navigation in experiments using physical iRobot Create mobile robots, simulations of multiple differential-drive robots or simple-airplanes, and video games levels containing hundreds of virtual agents.Doctor of Philosoph