Urbano Nunes

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Papers by Urbano Nunes

Reactive local navigation

IECON Proceedings (Industrial Electronics Conference), 2002

In this paper a reactive local navigation system is presented, for an autonomous non-holonomic mo... more In this paper a reactive local navigation system is presented, for an autonomous non-holonomic mobile robot navigating in dynamic environments. The reactive navigation system integrates an obstacle detection method [4] and a new reactive collision avoidance method. The sensory perception is based in a laser range finder (LRF) system. Simulation results are presented to verify the effectiveness of the proposed local navigation system in unknown environments with multiple moving objects. The comparison of results are shown, between two different approaches, a Velocity Obstacle (VO) approach and our own, based in the Dynamic Window (DW) concept.

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Electric vehicle simulator for energy consumption studies in electric mobility systems

2011 IEEE Forum on Integrated and Sustainable Transportation Systems, FISTS 2011, 2011

One of the most important environmental problems in large cities is the vehicular emission. Elect... more One of the most important environmental problems in large cities is the vehicular emission. Electric Vehicles (EVs) are a growing alternative for internal combustion engine (ICE) vehicles. Since this kind of vehicle has low autonomy yet, it is important to optimize energy consumption, for instance by planning a suitable infrastructure of battery recharge and/or battery-switch stations. This paper presents an architecture for EV simulation, important to analyze traffic flow, its dynamics and the performance when there are obstructions or intense traffic. There are several tools for traffic simulation, SUMO (Simulation of Urban MObility) is one of them. But none of the existing traffic simulators integrates models of EV that allow, for example, perform simulation studies regarding energy consumption. SUMO is a portable open source simulator with multi-modal traffic feature capabilities that permit the simulation of various types of vehicles. This work is an extension of the SUMO, two-dimensional (2D) vehicular simulation package. To allow the simulation of energy consumption of EV, two extensions were incorporated in SUMO: EV models and modeling of altitude, transforming SUMO into a threedimensional (3D) simulator. The energy model effectiveness and correctness with 3D capabilities has been validated using two driving schedules (Urban Dynamometer Driving Schedule and Highway Fuel Economy Driving Schedule). This new tool will also support the study of better routes choice in 3D environment with EV aiming minimum energy consumption.

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Algorithms for management of a multi-platooning system of IVC-enabled autonomous vehicles, with high traffic capacity

IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC, 2011

Intra-platoon positioning management strategies to deal with safe and efficient advanced traffic ... more Intra-platoon positioning management strategies to deal with safe and efficient advanced traffic management system operation are proposed in this paper. New algorithms to ensure high traffic capacity are proposed, and Matlab/Simulinkbased simulation results are reported. Recently, we proposed new algorithms to mitigate communication delays using anticipatory information, both from the platoon's leader and the followers, with significant impact on the improvement of platoon string stability . In this paper, we argue that maintaining a constant spacing between platoons' leaders has a positive impact on the traffic capacity of the whole system. As such, when the leader and eventually other vehicles immediately behind it leave the platoon, the new leader must accelerate to reach the position of the previous leader, to ensure inter-leader constant spacing and, consequently, enough spacing to be eventually occupied by new followers. We developed a novel architecture where each vehicle consists of two distinct modules: a leader and a follower. Based on Matlab/Simulink-based simulation, the new algorithms are assessed, and simulation results presented. The obtained simulation results confirm that the proposed algorithms adapt the acceleration pattern, ensuring similar timings for all possible cases of the previous position of new leaders in the platoon, when performing their repositioning maneuvers.

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Intelligent traffic management at intersections: Legacy mode for vehicles not equipped with V2V and V2I communications

16th International IEEE Conference on Intelligent Transportation Systems (ITSC 2013), 2013

ABSTRACT

Platooning of autonomous vehicles with intervehicle communications in SUMO traffic simulator

13th International IEEE Conference on Intelligent Transportation Systems, 2010

An approach to increase road capacity consists in making vehicles move much closer to each other,... more An approach to increase road capacity consists in making vehicles move much closer to each other, i.e. using platoons, and to avoid the constant stop-and-go in urban traffic. This paper addresses the studies of new models to allow the research of cooperative and autonomous communication-enabled vehicles, with platooning capabilities, and the addition of new features in SUMO (Simulation for Urban MObility) to allow the simulation of those models. Simulations results of vehicle platoons using constant spacing instead of the more common constant time headway, with intervehicle communications, are reported in the paper. The platoon leaders are controlled by an external application and the simulation platform works at the subsecond level.

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Real-Time Labeling of Places using Support Vector Machines

2007 IEEE International Symposium on Industrial Electronics, 2007

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Path-tracking controller with an anti-collision behaviour of a bi-steerable cybernetic car

This paper presents a path-tracking controller of a bi-steerable cybernetic car with an anti-coll... more This paper presents a path-tracking controller of a bi-steerable cybernetic car with an anti-collision behaviour. The velocity planner and the anti-collision system are fundamental modules in the architecture. The path tracking implementation uses fuzzy logic. The smoothness of the acceleration profile was one of requirements taken into account in the controller design. The anti-collision system based on Laser Range Data consists of estimating the trajectories and behaviour of surrounding objects. Simulation and experimental results are presented showing the effectiveness of the overall navigation control system.

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Sensor-based 3-D autonomous surface-following control

Mathematics and Computers in Simulation, 1996

Many industrial operations can be automated using robot arms that, however, require the use of ro... more Many industrial operations can be automated using robot arms that, however, require the use of robots being able to perform surface-following in an adaptive way. Surface-following in real-time based on sensor information is a delicate task to overtake, yet very useful in operations like painting, welding, glues administration and surface polishing. The surface-following can be accomplished either by using previous knowledge of the shape of the surface, by executing a sequence of movements point-by-point, or in an adaptive way. In the last case a sensor or a set of sensors for collecting data from the environment is used. Furthermore, the surface-following can be characterized by occur with or without robot-surface contact. The paper describes a 3-D surface-following controller. The surface-following operation is performed in real-time, out of contact using proximity information. Experimental results concerning 3-D surface-following movements performed by a PUMA 560 robot are shown.

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Platooning With IVC-Enabled Autonomous Vehicles: Strategies to Mitigate Communication Delays, Improve Safety and Traffic Flow

IEEE Transactions on Intelligent Transportation Systems, 2012

Intraplatoon information management strategies for dealing with safe and stable operation are pro... more Intraplatoon information management strategies for dealing with safe and stable operation are proposed in this paper. New algorithms to mitigate communication delays are presented, and Matlab/Simulink-based simulation results are reported. We argue that using anticipatory information from both the platoon's leader and the followers significantly impacts platoon string stability. The obtained simulation results suggest that the effects of communication delays may be almost completely canceled out. The platoon presents a very stable behavior, even when subjected to strong acceleration patterns. When the communication channel is subjected to a strong load, proper algorithms may be selected, lowering network load and maintaining string stability. Upon emergency occurrences, the platoon's timely response may be ensured by dynamically increasing the weight of the platoons' leaders data over the behavior of their followers. The simulation results suggest that the algorithms are robust under several demanding scenarios. To assess if current intervehicle communication technology can cope with the proposed information-updating schemes, research into its operation was conducted through a network simulator.

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Particle swarm-based olfactory guided search

Autonomous Robots, 2006

This article presents a new algorithm for searching odour sources across large search spaces with... more This article presents a new algorithm for searching odour sources across large search spaces with groups of mobile robots. The proposed algorithm is inspired in the particle swarm optimization (PSO) method. In this method, the search space is sampled by dynamic particles that use their knowledge about the previous sampled space and share this knowledge with other neighbour searching particles allowing the emergence of efficient local searching behaviours. In this case, chemical searching cues about the potential existence of upwind odour sources are exchanged. By default, the agents tend to avoid each other, leading to the emergence of exploration behaviours when no chemical cue exists in the neighbourhood. This behaviour improves the global searching performance. The article explains the relevance of searching odour sources with autonomous agents and identifies the main difficulties for solving this problem. A major difficulty is related with the chaotic nature of the odour transport in the atmosphere due to turbulent phenomena. The characteristics of this problem are described in detail and a simulation framework for testing and analysing different odour searching algorithms was constructed. The proposed PSO-based searching algorithm and modified versions of gradient-based searching and biased random walk-based searching strategies were tested in different environmental conditions and

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Guest Editorial Introducing Perception, Planning, and Navigation for Intelligent Vehicles

IEEE Transactions on Intelligent Transportation Systems, 2009

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High-resolution LIDAR-based depth mapping using bilateral filter

2016 IEEE 19th International Conference on Intelligent Transportation Systems (ITSC), 2016

High resolution depth-maps, obtained by upsampling sparse range data from a 3D-LIDAR, find applic... more High resolution depth-maps, obtained by upsampling sparse range data from a 3D-LIDAR, find applications in many fields ranging from sensory perception to semantic segmentation and object detection. Upsampling is often based on combining data from a monocular camera to compensate the low-resolution of a LIDAR. This paper, on the other hand, introduces a novel framework to obtain dense depth-map solely from a single LIDAR point cloud; which is a research direction that has been barely explored. The formulation behind the proposed depth-mapping process relies on local spatial interpolation, using sliding-window (mask) technique, and on the Bilateral Filter (BF) where the variable of interest, the distance from the sensor, is considered in the interpolation problem. In particular, the BF is conveniently modified to perform depthmap upsampling such that the edges (foreground-background discontinuities) are better preserved by means of a proposed method which influences the range-based weighting term. Other methods for spatial upsampling are discussed, evaluated and compared in terms of different error measures. This paper also researches the role of the mask's size in the performance of the implemented methods. Quantitative and qualitative results from experiments on the KITTI Database, using LIDAR point clouds only, show very satisfactory performance of the approach introduced in this work.

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Brain Computer Interface Approaches to Control Mobile Robotic Devices

Advances in Mobile Robotics, 2008

This paper presents and compares two approaches for brain computer interface to steer a wheelchai... more This paper presents and compares two approaches for brain computer interface to steer a wheelchair, namely a new visual based P300 paradigm consisting of 8 arrows randomly intensified used for direction selection and a motor imagery paradigm for discrimination of three commands. Classification follows Bayesian and Fisher Linear Discriminant approaches both based on prior statistical knowledge. Results in P300 paradigm reached false positive and false negative classification accuracies above 90%. Motor imagery experiments presented about 70% accuracy for left vs. right imagery and imagery vs. non-imagery.

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Low-cost, high performance servo-pneumatic manipulators with sensor feedback

Proceedings IEEE International Symposium on Intelligent Control 1988

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An RRT-based navigation approach for mobile robots and automated vehicles

2014 12th IEEE International Conference on Industrial Informatics (INDIN), 2014

Advances in autonomous navigation, safety, and natural-landmark based localization, are among the... more Advances in autonomous navigation, safety, and natural-landmark based localization, are among the key objectives in the development of the next generation of autonomous vehicles, to be deployed in manufacturing and semi-structured environments. In this paper, autonomous navigation and collision detection will be focused, where it is proposed a novel navigation approach that incorporates a RRT-based dynamic path planning and a path-following controller. Safety issues are taken into account in the form of a laser-based object detection and tracking. Experimental results obtained in a virtual environment provide evidence that our proposed navigation method is promising for real-world applications.

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Adaptation of powered wheelchairs for quadriplegic patients with reduced strength

IEEE Symposium on Emerging Technologies and Factory Automation, ETFA, 2008

Abstract This paper discusses the introduction of mechanisms to adapt commercial powered wheelcha... more

A cascade classifier applied in pedestrian detection using laser and image-based features

IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC, 2010

In this paper we present a multistage method applied in pedestrian detection using information fr... more In this paper we present a multistage method applied in pedestrian detection using information from a LIDAR and a monocular-camera mounted on an electric vehicle driving in urban scenarios. The proposed method is a cascade of classifiers trained in two subsets of features, one with laserbased features and the other with a set of image-based features. A specific training approach was developed to adjust the cascade stages in order to enhance the classification performance. The proposed method differs from the conventional cascade regarding the way the selected samples are propagated through the cascade. Thus, the subsequent stages of the proposed cascade receive both negatives and positives from previous ones, relying on a decision margin process. Experiments were conducted in off-line mode, for a set of single component classifiers and for the proposed cascade technique. The results are compared in terms of classification performance metrics and ROC curves.

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Can stereo vision replace a Laser Rangefinder?

IEEE International Conference on Intelligent Robots and Systems, 2012

An assisted navigation training framework based on judgment theory using sparse and discrete human-machine interfaces

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2009

This paper aims to present a new framework to train people with severe motor disabilities steerin... more This paper aims to present a new framework to train people with severe motor disabilities steering an assisted mobile robot (AMR), such as a powered wheelchair. Users with high level of motor disabilities are not able to use standard HMIs, which provide a continuous command signal (e. g. standard joystick). For this reason HMIs providing a small set of simple commands, which are sparse and discrete in time must be used (e. g. scanning interface, or brain computer interface), making very difficult to steer the AMR. In this sense, the assisted navigation training framework (ANTF) is designed to train users driving the AMR, in indoor structured environments, using this type of HMIs. Additionally it provides user characterization on steering the robot, which will later be used to adapt the AMR navigation system to human competence steering the AMR. A rule-based lens (RBL) model is used to characterize users on driving the AMR. Individual judgment performance choosing the best manoeuvres...

Sensors for mobile robot navigation

Lecture Notes in Control and Information Sciences, 1998

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