TechTalks from event: Technical session talks from ICRA 2012

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Localization II

  • Road Vehicle Localization with 2D Push-Broom Lidar and 3D Priors Authors: Baldwin, Ian Alan; Newman, Paul
    In this paper we describe and demonstrate a method for precisely localizing a road vehicle using a single push-broom 2D laser scanner while leveraging a prior 3D survey. In contrast to conventional scan matching, our laser is oriented downwards, thus causing continual ground strike. Our method exploits this to produce a small 3D swathe of laser data which can be matched statistically within the 3D survey. This swathe generation is predicated upon time varying estimates of vehicle velocity. While in theory this data could be obtained from vehicle speedometers, in reality these instruments are biased and so we also provide a way to estimate this bias from survey data. We show that our low cost system consistently outperforms a high calibre integrated DGPS/IMU system over 26 km of driven path around a test site.
  • Radar-Only Localization and Mapping for Ground Vehicle at High Speed and for Riverside Boat Authors: VIVET, DAMIEN; Checchin, Paul; CHAPUIS, Roland
    The use of a rotating range sensor in high speed robotics creates distortions in the collected data. Such an effect is, in the majority of studies, ignored or considered as a noise and then corrected, based on proprioceptive sensors or localization systems. In this study we consider that distortion contains the information about the vehicle's displacement. We propose to extract this information from distortion without any other information than exteroceptive sensor data. The only sensor used for this work is a panoramic Frequency Modulated Continuous Wave (FMCW) radar called K2Pi. No odometer, gyrometer or other proprioceptive sensor is used. The idea is to resort to velocimetry by analyzing the distortion of the measurements. As a result, the linear and angular velocities of the mobile robot are estimated and used to build, without any other sensor, the trajectory of the vehicle and then the radar map of outdoor environments. In this paper, radar-only localization and mapping results are presented for a ground vehicle and a riverbank application. This work can easily be extended to other slow rotating range sensors.
  • LAPS - Localisation using Appearance of Prior Structure: 6-DoF Monocular Camera Localisation using Prior Pointclouds Authors: Stewart, Alex; Newman, Paul
    This paper is about pose estimation using monocular cameras with a 3D laser pointcloud as a workspace prior. We have in mind autonomous transport systems in which low cost vehicles equipped with monocular cameras are furnished with preprocessed 3D lidar workspaces surveys. Our inherently cross-modal approach offers robustness to changes in scene lighting and is computationally cheap. At the heart of our approach lies inference of camera motion by minimisation of the Normalised Information Distance (NID) between the appearance of 3D lidar data reprojected into overlapping images. Results are presented which demonstrate the applicability of this approach to the localisation of a camera against a lidar pointcloud using data gathered from a road vehicle.
  • An Outdoor High-Accuracy Local Positioning System for an Autonomous Robotic Golf Greens Mower Authors: Smith, Aaron; Chang, H. Jacky; Blanchard, Edward
    This paper presents a high-accuracy local positioning system (LPS) for an autonomous robotic greens mower. The LPS uses a sensor tower mounted on top of the robot and four active beacons surrounding a target area. The proposed LPS concurrently determines robot location using a lateration technique and calculates orientation using angle measurements. To perform localization, the sensor tower emits an ultrasonic pulse that is received by the beacons. The time of arrival is measured by each beacon and transmitted back to the sensor tower. To determine the robot’s orientation, the sensor tower has a circular receiver array that detects infrared signals emitted by each beacon. Using the direction and strength of the received infrared signals, the relative angles to each beacon are obtained and the robot orientation can be determined. Experimental data show that the LPS achieves a position accuracy of 3.1 cm RMS, and an orientation accuracy of 0.23° RMS. Several prototype robotic mowers utilizing the proposed LPS have been deployed for field testing, and the mowing results are comparable to an experienced professional human worker.
  • Curb-Intersection Feature Based Monte Carlo Localization on Urban Roads Authors: Qin, Baoxing; Chong, Zhuang Jie; Bandyopadhyay, Tirthankar; Ang Jr, Marcelo H; Frazzoli, Emilio; Rus, Daniela
    One of the most prominent features on an urban road is the curb, which defines the boundary of a road surface. An intersection is a junction of two or more roads, appearing where no curb exists. The combination of curb and intersection features and their idiosyncrasies carry significant information about the urban road network that can be exploited to improve a vehicle's localization. This paper introduces a Monte Carlo Localization (MCL) method using the curb-intersection features on urban roads. We propose a novel idea of "Virtual LIDAR" to get the measurement models for these features. Under the MCL framework, above road observation is fused with odometry information, which is able to yield precise localization. We implement the system using a single tilted 2D LIDAR on our autonomous test bed and show robust performance in the presence of occlusion from other vehicles and pedestrians.
  • Satellite Image Based Precise Robot Localization on Sidewalks Authors: Senlet, Turgay; Elgammal, Ahmed
    In this paper, we present a novel computer vision framework for precise localization of a mobile robot on sidewalks. In our framework, we combine stereo camera images, visual odometry, satellite map matching, and a sidewalk probability transfer function obtained from street maps in order to attain globally corrected localization results. The framework is capable of precisely localizing a mobile robot platform that navigates on sidewalks, without the use of traditional wheel odometry, GPS or INS inputs. On a complex 570-meter sidewalk route, we show that we obtain superior localization results compared to visual odometry and GPS.

Results of ICRA 2011 Robot Challenge

  • A Modular Control System for Warehouse Automation - Algorithms and Simulations in USARSim Authors: Miklic, Damjan; Petrovic, Tamara; Coric, Mirko; Piskovic, Zvonimir; Bogdan, Stjepan
    In this paper, we present a control system for a fully autonomous material handling facility. The scenario we are considering is motivated by the 2011 IEEE Virtual Manufacturing Automation Challenge (VMAC). It consists of multiple autonomously guided vehicles (AGVs), transporting pallets of various goods between several input and output locations, through an unstructured warehouse environment. Only a map of the warehouse and a pallet delivery list are provided a priori. Pallets must be delivered to the output locations in the shortest time possible, while respecting the ordering of different pallet types specified by the delivery list. The presented control system handles all aspects of warehouse operation, from individual vehicle control to high-level mission planning and coordination. Delivery mission assignments are optimized using dynamic programming and simulated annealing techniques. Mission executions are coordinated using graph search methods and a modified version of the Banker's algorithm, to ensure safe, collision and deadlock-free system operation. System performance is evaluated on a virtual warehouse model, using the high fidelity USARSim simulator.
  • Wireless Swimming Microrobots: Design and Development of a 2 DoF Magnetic-Based System Authors: Palagi, Stefano; Lucarini, Gioia; Pensabene, Virginia; Levi, Alessandro; Mazzolai, Barbara; Menciassi, Arianna; Beccai, Lucia
    In this work, the design and development of an integrated platform for the steering of swimming microrobot is reported. The system consists of: a near-spherical soft and buoyant magnetic microrobot (with a diameter of about 500 µm) conceived for operation in liquid; a wireless magnetic steering system, including a compact magnetic field generator based on two pairs of Helmholtz and Maxwell coils; an electronic system for their driving; a control software; a joypad physical user interface; and, the micro-arena as working environment. The platform design fulfills the requirements for the “Mobility Task” of the 2011 NIST Mobile Microrobotics Challenge. The results obtained from preliminary validation experiments confirm that the microrobots can move in a fully controlled way, successfully accomplishing an intricate eight-shape path, as required, in the water filled micro-arena. In particular we achieved a maximum average speed of 0.71 mm/s and an exceptionally smooth motion.
  • Toward Fluidic Microrobots Using Electrowetting Authors: Schaler, Ethan; Tellers, Mary; Gerratt, Aaron P.; Penskiy, Ivan; Bergbreiter, Sarah
    This paper describes the performance of a fluidic microrobot using Electrowetting on Dielectric (EWOD). A system to control the fluidic microrobot was designed, constructed and deployed in the NIST Mobile Microrobotics Challenge at ICRA 2011. The microrobots (0.1 M KCl and 550 μm diameter) demonstrated the ability to perform controlled maneuvers in 2-D while transporting hydrophilic objects. The EWOD system is composed of a DIP-mounted die produced via standard microfabrication techniques and containing the control electrodes / competition arena, and a transparent ITO cover slip for grounding. Key advantages of this platform include a scalable design for batch EWOD system fabrication, potential simultaneous control of multiple microrobots, and an easily portable, compact system design.
  • A Textured Object Recognition Pipeline for Color and Depth Image Data Authors: Tang, Jie; Miller, Stephen; Singh, Arjun; Abbeel, Pieter
    We present an object recognition system which leverages the additional sensing and calibration information available in a robotics setting together with large amounts of training data to build high fidelity object models for a dataset of textured household objects. We then demonstrate how these models can be used for highly accurate detection and pose estimation in an end-to-end robotic perception system incorporating simultaneous segmentation, object classification, and pose fitting. The system can handle occlusions, illumination changes, multiple objects, and multiple instances of the same object. The system placed first in the ICRA 2011 Solutions in Perception instance recognition challenge. We believe the presented paradigm of building rich 3D models at training time and including depth information at test time is a promising direction for practical robotic perception systems.
  • The Jacobs Robotics Approach to Object Recognition and Localization in the Context of the ICRA'11 Solutions in Perception Challenge Authors: Vaskevicius, Narunas; Pathak, Kaustubh; Ichim, Alexandru-Eugen; Birk, Andreas
    In this paper, we give an overview of the Jacobs Robotics entry to the ICRA'11 Solutions in Perception Challenge. We present our multi-pronged strategy for object recognition and localization based on the integrated geometric and visual information available from the Kinect sensor. Firstly, the range image is over-segmented using an edge-detection algorithm and regions of interest are extracted based on a simple shape-analysis per segment. Then, these selected regions of the scene are matched with known objects using visual features and their distribution in 3D space. Finally, generated hypotheses about the positions of the objects are tested by back-projecting learned 3D models to the scene using estimated transformations and sensor model.

Teleoperation

  • Bilateral Teleoperation of Cooperative Manipulators Authors: Aldana, Carlos Iván; Nuno, Emmanuel; Basanez, Luis
    This paper presents an adaptive controller for the bilateral teleoperation of a system composed by a single local manipulator and multiple cooperative remote manipulators handling a common object. First, the nonlinear operational space dynamical behavior, of the complete teleoperation system, is derived and then, under the assumptions that the remote manipulators are rigidly grasping a non-deformable object and that the communications may induce constant time-delays, it is proved that velocities and position-orientation error between the local manipulator end-effector and the object asymptotically converge to zero. Simulations results are included to show the effectiveness of the proposed scheme.
  • Direct Force Reflecting Teleoperation with a Flexible Joint Robot Authors: Tobergte, Andreas; Albu-Schäffer, Alin
    This paper presents a high fidelity force feedback teleoperation control for surgical applications. Advanced control methods, such as flexible joint tracking control and passivity observation, are introduced in the direct force reflecting control architecture. A full state feedback controller of the flexible joint slave robot controls the motor position, velocity, the joint torque, and the torque derivative. The pose of the haptic device and the first three derivatives are observed to generate reference states for the robot control using the robot's inverse dynamics model. Interaction forces of the slave and the environment are measured with a force/torque sensor and directly sent back to the master device. Stability is guaranteed with a passivity observer that monitors the energy in the teleoperation system online and disconnects master and slave if the system operates beyond its stable region. The proposed control architecture is implemented with the sigma.7 haptic device and the MIRO robot. It is experimentally shown, that appropriately considering elasticities with full state reference and control of the slave, increases the dynamic range of the system enabling transparent and stable interaction with hard and soft environments.
  • Dynamic Scaling Interface for Assisted Teleoperation Authors: Munoz, Luis Miguel; Casals, Alicia
    Teleoperation, by adequately adapting computer interfaces, can benefit from the knowledge on human factors and psychomotor models in order to improve the effectiveness and efficiency in the execution of a task. While scaling is one of the performances frequently used in teleoperation tasks that require high precision, such as surgery, this article presents a scaling method that considers the system dynamics as well. The proposed dynamic scaling factor depends on the apparent position and velocity of the robot and targets. Such scaling improves the performance of teleoperation interfaces, thereby reducing user’s workload.
  • A Proportional Plus Damping Injection Controller for Teleoperators with Joint Flexibility and Time-Delays Authors: Nuno, Emmanuel; Sarras, Ioannis; Basanez, Luis; Kinnaert, Michel
    The problem of controlling a rigid bilateral teleoperator with time-delays has been effectively addressed since the late 80's. However, the control of flexible joint manipulators in a bilateral teleoperation scenario is still an open problem. In the present paper we report two versions of a proportional plus damping injection controller that are capable of globally stabilizing a nonlinear bilateral teleoperator with joint flexibility and variable time-delays. The first version controls a teleoperator composed by a rigid local manipulator and a flexible joint remote manipulator and the second version deals with local and remote manipulators with joint flexibility. For both schemes, it is proved that the joint and motor velocities and the local and remote position error are bounded. Moreover, if the human operator and remote environment forces are zero then velocities asymptotically converge to zero and position tracking is established. Simulations are presented to show the performance of the proposed controllers.
  • Stability of Position-Based Bilateral Telemanipulation Systems by Damping Injection Authors: Franken, Michel; Misra, Sarthak; Stramigioli, Stefano
    In this paper two different approaches to guaran- tee stability of bilateral telemanipulation systems are discussed. Both approaches inject damping into the system to guarantee passivity of the interaction with the device in the presence of time delays in the communication channel. The first approach derives tuning rules for a fixed viscous damper, whereas the second approach employs modulated dampers based upon the measured energy exchange with the device and enforces passivity in the time domain. Furthermore, a theoretical min- imum damping injection scheme is sketched that shows that the fixed damping approach is inherently conservative with respect to guaranteeing stability. Experimental results show that both the theoretical minimum damping scheme and a time domain passivity algorithm are successful in stabilizing the telemanipulation system for large time delays with lower gains of the damping elements than derived by the fixed damping injection approach. However, as damping is inherently present in the system, the tuning rules derived from the fixed damping injection approach can be used to identify if a time domain passivity algorithm is needed given boundary conditions on the actual time delays.
  • Bilateral Teleoperation of a Group of UAVs with Communication Delays and Switching Topology Authors: Secchi, Cristian; Franchi, Antonio; Buelthoff, Heinrich H.; Robuffo Giordano, Paolo
    In this paper, we present a passivity-based decentralized approach for bilaterally teleoperating a group of UAVs composing the slave side of the teleoperation system. In particular, we explicitly consider the presence of time delays, both among the master and slave, and within UAVs composing the group. Our focus is on analyzing suitable (passive) strategies that allow a stable teloperation of the group despite presence of delays, while still ensuring high flexibility to the group topology (e.g., possibility to autonomously split or join during the motion). The performance and soundness of the approach is validated by means of human/hardware-in-the-loop simulations (HHIL).