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arXiv 2017年

作者： Lambert, Jacob Clement, Lee Giamou, Matthew Kelly, Jonathan Space and Terrestrial Autonomous Robotic Systems Laboratory Institute for Aerospace Studies University of Toronto Laboratory for Information and Decision Systems Massachusetts Institute of Technology

This paper explores the use of an entropy-based technique for point cloud reconstruction with the goal of calibrating a lidar to a sensor capable of providing egomotion information. We extend recent work in this area to the problem of recovering the Sim(3) transformation between a 2D lidar and a rigidly attached monocular camera, where the scale of the camera trajectory is not known a priori. We demonstrate the robustness of our approach on realistic simulations in multiple environments, as well as on data collected from a hand-held sensor rig. Given a non-degenerate trajectory and a sufficient number of lidar measurements, our calibration procedure achieves millimetre-scale and sub-degree accuracy. Moreover, our method relaxes the need for specific scene geometry, fiducial markers, or overlapping sensor fields of view, which had previously limited similar techniques. Copyright © 2017, The Authors. All rights reserved.

关键词： Optical radar

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spacecraft heath monitoring using a biomimetic fault diagnosis scheme

Spacecraft heath monitoring using a biomimetic fault diagnos...

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AIAA Information systems-Infotech At Aerospace Conference, 2017

作者： Garcia, Diego F. Perez, Andres E. Moncayo, Hever Rivera, Karina Du Puis, Michael Mueller, Robert P. Department of Aerospace Engineering Flight Dynamics and Control Research Laboratory Embry-Riddle Aeronautical University United States Robotics and Autonomous Systems Testing and Design Branch NASA Kennedy Space Center Swamp Works Laboratory United States Science and Technology Projects Division NASA Kennedy Space Center Swamp Works Laboratory United States

ISBN: (纸本)9781624104497

This paper presents the design, development and implementation of a bio-inspired fault diagnosis scheme applied to a cold gas based spacecraft prototype. The proposed framework relies on the Artificial Immune System metaphor (AIS) with the goal of monitoring the health of the spacecraft by detecting subsystem upset conditions such as actuator malfunctions. A non-linear dynamic inversion (NLDI) baseline controller has been developed and implemented for attitude control of the spacecraft. The performance of the proposed health monitoring scheme is determined by analyzing the system response under different actuator failures and the results show acceptable performance in terms of high detection rate and low false alarms. The application of this artificial intelligent based scheme to aerospace systems will provide a high impact on space exploration by increasing mission protection and performance. © 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Attitude control

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Design and realization of a 6 degree of freedom robotic extrusion platform 27

Design and realization of a 6 degree of freedom robotic extr...

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27th Annual International Solid Freeform Fabrication Symposium - An Additive Manufacturing Conference, SFF 2016

作者： Kubalak, Joseph R. Mansfield, Craig D. Pesek, Taylor H. Snow, Zachary K. Cottiss, Edward B. Ebeling-Koning, Oliver D. Price, Matthew G. Traverso, Mark H. Tichnell, L. David Williams, Christopher B. Wicks, Alfred L. Design Research and Education for Additive Manufacturing Systems Laboratory Mechatronics and Autonomous Vehicles Laboratory Terrestrial Robotics Engineering and Controls Laboratory Department of Mechanical Engineering Polymer Processing Laboratory Department of Chemical Engineering Virginia Tech United States

The layer-wise deposition of Additive Manufacturing (AM) processes allows for significant freedom in the design of product geometry;however, the use of 3-axis deposition tools results in layer interfaces that reduce material properties in the build direction. Adding additional degrees-of-freedom (DOF) to the AM tool could remove this limitation by enabling out of plane material deposition. For example, multi-DOF tool paths could align material extrusion with a part's stress contours to circumvent inter-layer delamination. As a step towards this goal, the authors designed, fabricated, and tested an AM extrusion system that leverages a 6-DOF robotic arm. In this paper, the authors detail the realization of this system including the design of a high-temperature filament extruder, kinematics and tool path generation, and user interface. The performance of the system is evaluated through layered deposition of ABS thermoplastic. © 2016 The Department of Energy’s Kansas City National Security Campus is operated and managed by Honeywell Federal Manufacturing Technologies, LLC under contract number DE-NA0002839.

关键词： 3D printers

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PROBE-GK: Predictive robust estimation using generalized kernels

PROBE-GK: Predictive robust estimation using generalized ker...

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IEEE International Conference on robotics and Automation (ICRA)

作者： Valentin Peretroukhin William Vega-Brown Nicholas Roy Jonathan Kelly Space & Terrestrial Autonomous Robotic Systems Laboratory University of Toronto Robust Robotics Group Massachusetts Institute of Technology

ISBN: (纸本)9781467380270

Many algorithms in computer vision and robotics make strong assumptions about uncertainty, and rely on the validity of these assumptions to produce accurate and consistent state estimates. In practice, dynamic environments may degrade sensor performance in predictable ways that cannot be captured with static uncertainty parameters. In this paper, we employ fast nonparametric Bayesian inference techniques to more accurately model sensor uncertainty. By setting a prior on observation uncertainty, we derive a predictive robust estimator, and show how our model can be learned from sample images, both with and without knowledge of the motion used to generate the data. We validate our approach through Monte Carlo simulations, and report significant improvements in localization accuracy relative to a fixed noise model in several settings, including on synthetic data, the KITTI dataset, and our own experimental platform.

关键词： Predictive models Robustness Visualization Optimization Transforms Cameras Estimation

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Entropy-based sim(3) calibration of 2D lidars to egomotion sensors

Entropy-based sim(3) calibration of 2D lidars to egomotion s...

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International Conference on Multisensor Fusion and Integration for Intelligent systems (MFI)

作者： Jacob Lambert Lee Clement Matthew Giamou Jonathan Kelly Space and Terrestrial Autonomous Robotic Systems Laboratory University of Toronto Laboratory for Information and Decision Systems Massachusetts Institute of Technology

ISBN: (纸本)9781467397087

关键词： Sensors Laser radar Cameras Calibration Three-dimensional displays Trajectory Entropy

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Control laws development for a free-flying unmanned robotic system to support interplanetary bodies prospecting and characterization missions

Control laws development for a free-flying unmanned robotic ...

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AIAA Guidance, Navigation, and Control Conference, 2016

作者： Perez, Andres E. Moncayo, Hever Prazenica, Richard J. Zacny, Kris Mueller, Robert P. Ebert, Tom Dupuis, Michael Flight Dynamics and Control Research Laboratory Embry-Riddle Aeronautical University Daytona BeachFL32114 United States Aerospace Engineering Department Embry-Riddle Aeronautical University Daytona BeachFL32114 United States Exploration Technology Group Honneybee Robotics Company CA United States Exploration Research and Technology Programs Science and Technology Projects Division NASA Kennedy Space Center FL United States Autonomous Flight Systems Lead Testing and Design Branch NASA Kennedy Space Center FL United States Robotics and Autonomous Systems Testing and Design Branch NASA Kennedy Space Center FL United States

ISBN: (数字)9781624103896

ISBN: (纸本)9781624103896

In situ Resource Utilization (ISRU) facilitates planetary exploration by drawing needed resources, such as water, from the local environment. However, the extreme nature of these environments require the development of advanced unmanned space systems integrated with sample-capture devices to achieve the ultimate goal of prospecting these resources. This paper presents the design, development and Hardware-in-the-Loop (HIL) simulation testing of guidance and tracking control laws for an autonomous small marsupial free-flyer prospector system. The control laws are based on an extended non-linear dynamic inversion (NLDI) approach and its implementation is illustrated through HIL simulation using a mathematical model of an autonomous vehicle research platform developed by NASA Kennedy space Center. This vehicle has been designed to support the development, testing and validation of algorithms for safe, reliable, and scalable control space missions with minimal need for human intervention in complex, unstructured environments. The main objective of the control laws is to minimize 3-axis distances with respect to a desired trajectory and maintain stability and adequate performance in the presence of uncertainties. The performance of the control laws is evaluated during autonomous flight in terms of trajectory tracking errors, real-time execution on board the flight computer, and control activity at nominal and dynamically-changing conditions. The results show that for all mission cases investigated the control laws approach has desirable capabilities and is reliable for in-flight testing operation as a next step towards the validation and verification of this configuration. © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Hardware-in-the-loop simulation

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Gaussian Process Gauss-Newton: Non-Parametric State Estimation

Gaussian Process Gauss-Newton: Non-Parametric State Estimati...

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Canadian Conference on Computer and Robot Vision, CRV

作者： Chi Hay Tong Paul Furgale Timothy D. Barfoot Autonomous Space Robotics Laboratory University of Toronto Toronto Canada Autonomous Systems Laboratory ETH Zürich Zurich Switzerland

In this paper, we present Gaussian Process Gauss-Newton (GPGN), an algorithm for non-parametric, continuous-time, nonlinear, batch state estimation. This work adapts the methods of Gaussian Process regression to the problem of batch state estimation by using the Gauss-Newton method. In particular, we formulate the estimation problem with a continuous-time state model, along with the more conventional discrete-time measurements. Our derivation utilizes a basis function approach, but through algebraic manipulations, returns to a non-parametric form by replacing the basis functions with covariance functions (i.e., the kernel trick). The algorithm is validated through hardware-based experiments utilizing the well-understood problem of 2D rover localization using a known map as an illustrative example, and is compared to the traditional discrete-time batch Gauss-Newton approach.

关键词： State estimation Robot sensing systems Time measurement Mathematical model Random variables

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Exploiting Reusable Paths in Mobile robotics: Benefits and Challenges for Long-term Autonomy

Exploiting Reusable Paths in Mobile Robotics: Benefits and C...

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Canadian Conference on Computer and Robot Vision, CRV

作者： Timothy D. Barfoot Braden Stenning Paul Furgale Colin McManus Autonomous Space Robotics Laboratory University of Toronto Institute for AeroSpace Studies Toronto Canada Autonomous Systems Laboratory ETH Zürich Zurich Switzerland Mobile Robotics Group University of Oxford Oxford UK

Visual-teach-and-repeat (VT&R) systems have proven extremely useful for practical robot autonomy where the global positioning system is either unavailable or unreliable, examples include tramming for underground mining using a planar laser scanner as well as a return-to-lander function for planetary exploration using a stereo-or laser-based camera. By embedding local appearance/metric information along an arbitrarily long path, it becomes possible to re-drive the path without the need for a single privileged coordinate frame and using only modest computational resources. For a certain class of long-term autonomy problems (e.g., repeatable long-range driving), VT&R appears to offer a simple yet scalable solution. Beyond single paths, we envision that networks of reusable paths could be established and shared from one robot to another to enable practical tasks such as surveillance, delivery (e.g., mail, hospitals, factories, warehouses), worksite operations (e.g., construction, mining), and autonomous roadways. However, for lifelong operations on reusable paths, robustness to a variety of environmental changes, both transient and permanent, is required. In this paper, we relate our experiences and lessons learned with the three above-mentioned implementations of VT&R systems. Based on this, we enumerate both the benefits and challenges of reusable paths that we see moving forwards. We discuss one such challenge, lighting-invariance, in detail and present our progess in overcoming it.

关键词： Robot kinematics Visualization Lighting Lasers Mobile robots Simultaneous localization and mapping

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Improvements of the International Reference Ionosphere model for the topside electron density profile

Improvements of the International Reference Ionosphere model...

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作者： Bilitza, Dieter Reinisch, Bodo W. Radicella, Sandro M. Pulinets, Sergey Gulyaeva, Tamara Triskova, Lida Raytheon Intelligence and Information Systems Goddard Space Flight Center Greenbelt MD United States Center for Atmospheric Research University of Massachusetts Lowell MA United States Aeronomy and Radiopropagation Laboratory Abdus Salam International Centre for Theoretical Physics Trieste Italy Institute of Geophysics National Autonomous University of Mexico Mexico D.F. Mexico Institute of Terrestrial Magnetism Ionosphere and Radiowave Propagation Moscow Russia Space Research Center Polish Academy of Sciences Warsaw Poland Institute of Atmospheric Physics Academy of Sciences Prague Czech Republic Raytheon IIS GSFC Code 612.4 Greenbelt MD 20771 United States IZMIRAN 142190 Troitsk Moscow Russia Institute of Geophysics National Autonomous University of Mexico Ciudad Universitaria Del. Coyoacan Mexico D.F. 04510 Mexico Aeronomy and Radiopropagation Laboratory Abdus Salam International Centre for Theoretical Physics Strada Costiera 11 I-34014 Trieste Italy Center for Atmospheric Research University of Massachusetts 600 Suffolk Street Lowell MA 01854 United States Institute of Atmospheric Physics Academy of Sciences Boèní II 141 31 Praha 4 Czech Republic

Shortcomings of the representation of the topside electron density profile in the International Reference Ionosphere (IRI) model have been noted in comparison with recently analyzed topside sounder data and also with total electron content (TEC) data. Various studies have proposed corrections of the IRI formulas or have introduced a new formalism. This paper reviews the different approaches, their implications for IRI, and their current status. An important challenge for topside modeling is the truthful representation of profiles in the equatorial anomaly (EA) region over the whole range of the EA fountain. This means that the latitudinal representation has to reproduce the merging of the double-peak signature at F region heights into a single peak at the top of the fountain. In this context, special emphasis is given to the coupling between topside and plasmaspheric models. Copyright 2006 by the American Geophysical Union.

关键词： Ionosphere

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