12 research outputs found
Rotorcraft Flight Simulation Model Fidelity Improvement and Assessment - Final report of NATO STO AVT-296 Research Task Group
Rotorcraft flight dynamics simulation models require high levels of fidelity to be suitable as prime items in support of life cycle practices, particularly vehicle and control design and development, and system and trainer certification. On the civil side, both the FAA (US) and EASA (Europe) have documented criteria (metrics and practices) for assessing model and simulator fidelity as compared to flight-test data, although these have not been updated for several decades. On the military side, the related practices in NATO nations are not harmonised and often only developed for specific applications. Methods to update the models for improved fidelity are mostly ad hoc and lack a rational and methodical approach. Modern rotorcraft System Identification (SID) and inverse simulation methods have been developed in recent years that provide new approaches well suited to pilot-in-the-loop fidelity assessment and systematic techniques for updating simulation models to achieve the needed level of fidelity. To coordinate efforts and improve the knowledge in this area, STO Applied Vehicle Technology Panel Research Task Group (STO AVT-296 RTG) was constituted to evaluate update methods used by member nations to find best practices and suitability for different applications including advanced rotorcraft configurations. This report presents the findings of the AVT-296 RTG. An overview of previous rotorcraft simulation fidelity Working Groups is presented, followed by a review of the metrics that have been used in previous studies to quantify the fidelity of a flight model or the overall perceptual fidelity of a simulator. The theoretical foundations of the seven different update methods and a description of the eight flight databases (Bell 412, UH-60, IRIS+, EC135, CH-47, AW139, AW109, and X2, provided by the National Research Council of Canada, US Army, Airbus Helicopters, Boeing, Leonardo Helicopter Division, and Sikorsky) used by the RTG is presented. Both time- and frequency-domain fidelity assessment methods are considered, including those in current use by simulator qualification authorities and those used in the research community. Case studies are used to show the application, utility, and limitations of the update and assessment methods to the flight-test data. The work of the RTG has shown that time- and frequency-domain SID based metrics are suitable for use for assessing the model fidelity across a wide range of rotorcraft configurations. Gain and time delay update methods work well for well-developed flight dynamics models and can be used for flight control system design, but do not provide physical insights into the sources of errors in a model. Deriving stability and control derivatives from flight-test data using SID and nonlinear simulation models using perturbation extraction methods provides insight into the missing dynamics of the simulation model, which can subsequently be updated using additional forces and moments to significantly improve the fidelity of the model and can be used to update models for flight simulation training application methods. Reduced order model and physics-based correction methods provide large benefits when extrapolating to other flight conditions but does require detailed flight-test data. SID can quickly provide accurate point models, if detailed flight-test data are available, which can be âstitchedâ together to produce models suitable for real-time piloted simulation and control design applications. However, the dependency on flight-test data means that this method is not suitable for early aircraft development activities. This documentation of rotorcraft simulation fidelity assessment and model update strategies will benefit NATO nations by allowing for common, agreed-upon best practices and recommendations, ensuring each countryâs flight dynamics and simulation models are of the highest calibre possible. The collaboration between industry, academia, and government laboratories has been key to the success of this RTG; this cooperation model should be adopted in future research activities. As industries strive to achieve greater efficiency and safety in their products, the fidelity of simulation should match commercial aspirations to ensure that the âright first timeâ ethos is fully embedded into industrial best practices. Militaries will be able to use the methods and metrics presented to set criteria that will underpin the use of modelling and simulation in certification to accelerate development and acquisition and reduce the cost of new aircraft systems, e.g., advanced high-speed rotorcraft and legacy system upgrades. The criteria may also set standards for training devices used to support the expansion of synthetic environments for training to offset the high costs of flight hours. This RTG has identified that current flight training simulator standards could be updated to use the flight model and perceptual fidelity metrics presented in this report to ensure that models are not âover-tunedâ and a more rigorous method of subjective simulator assessment is adopted
Proceedings of the NASA Conference on Space Telerobotics, volume 2
These proceedings contain papers presented at the NASA Conference on Space Telerobotics held in Pasadena, January 31 to February 2, 1989. The theme of the Conference was man-machine collaboration in space. The Conference provided a forum for researchers and engineers to exchange ideas on the research and development required for application of telerobotics technology to the space systems planned for the 1990s and beyond. The Conference: (1) provided a view of current NASA telerobotic research and development; (2) stimulated technical exchange on man-machine systems, manipulator control, machine sensing, machine intelligence, concurrent computation, and system architectures; and (3) identified important unsolved problems of current interest which can be dealt with by future research
Predictive-model-based MIMO motion control of an unstable 6-DoF hexapod stage for overlay measurements
Correct functionality of semiconductor devices depends on the overlay performance between device layers. Future smaller device features consequently require more accurate overlay metrology tools. In this paper we present a large dynamic range AFM overlay tool to directly measure marker-to-feature distances, and focus on the controller design of the large stroke 6-DoF hexapod motion stage which is at the heart of this tool. The stage is open-loop unstable due to magnetic gravity compensation, which calls for an initial model-based MIMO controller design, which is based on a finite-element modal analysis, geometric decoupling and SISO loopshaping. This controller is successfully validated in experiments; further controller improvements after closed-loop system identification yield a closed-loop position error of just 1 nm RMS
Predictive-model-based MIMO motion control of an unstable 6-DoF hexapod stage for overlay measurements
\u3cp\u3eCorrect functionality of semiconductor devices depends on the overlay performance between device layers. Future smaller device features consequently require more accurate overlay metrology tools. In this paper we present a large dynamic range AFM overlay tool to directly measure marker-to-feature distances, and focus on the controller design of the large stroke 6-DoF hexapod motion stage which is at the heart of this tool. The stage is open-loop unstable due to magnetic gravity compensation, which calls for an initial model-based MIMO controller design, which is based on a finite-element modal analysis, geometric decoupling and SISO loopshaping. This controller is successfully validated in experiments; further controller improvements after closed-loop system identification yield a closed-loop position error of just 1 nm RMS.\u3c/p\u3
Using MapReduce Streaming for Distributed Life Simulation on the Cloud
Distributed software simulations are indispensable in the study of large-scale life models but often require the use of technically complex lower-level distributed computing frameworks, such as MPI. We propose to overcome the complexity challenge by applying the emerging MapReduce (MR) model to distributed life simulations and by running such simulations on the cloud. Technically, we design optimized MR streaming algorithms for discrete and continuous versions of Conwayâs life according to a general MR streaming pattern. We chose life because it is simple enough as a testbed for MRâs applicability to a-life simulations and general enough to make our results applicable to various lattice-based a-life models. We implement and empirically evaluate our algorithmsâ performance on Amazonâs Elastic MR cloud. Our experiments demonstrate that a single MR optimization technique called strip partitioning can reduce the execution time of continuous life simulations by 64%. To the best of our knowledge, we are the first to propose and evaluate MR streaming algorithms for lattice-based simulations. Our algorithms can serve as prototypes in the development of novel MR simulation algorithms for large-scale lattice-based a-life models.https://digitalcommons.chapman.edu/scs_books/1014/thumbnail.jp
Conference on Thermal Issues in Machine Tools: Proceedings
Inhomogeneous and changing temperature distributions in machine tools lead to sometimes considerable quality problems in the manufacturing process. In addition, the switching on and off of aggregates, for example, leads to further fluctuations in the temperature field of machine tools. More than 100 specialists discussed these and other topics from the field of thermal research at the 1st Conference on Termal Issues in Machine Tools in Dresden from 22 to 23 March.:Efficient modelling and computation of structure-variable thermal behavior of machine tools
S. Schroeder, A. Galant, B. Kauschinger, M. Beitelschmidt
Parameter identification software for various thermal model types
B. Hensel, S. Schroeder, K. Kabitzsch
Minimising thermal error issues on turning centre
M. MareĆĄ, O. HorejĆĄ, J. Hornych
The methods for controlled thermal deformations in machine tools
A. P. Kuznetsov, H.-J. Koriath, A.O. Dorozhko
Efficient FE-modelling of the thermo-elastic behaviour of a machine tool slide in lightweight design
C. Peukert, J. MĂŒller, M. Merx, A. Galant, A. Fickert, B. Zhou, S. StĂ€dtler, S. Ihlenfeldt, M. Beitelschmidt
Development of a dynamic model for simulation of a thermoelectric self-cooling system for linear direct drives in machine tools
E. Uhlmann, L. Prasol, S.Thom, S. Salein, R. Wiese
System modelling and control concepts of different cooling system structures for machine tools
J. Popken, L. Shabi, J. Weber, J. Weber
The electric drive as a thermo-energetic black box
S. Winkler, R. Werner
Thermal error compensation on linear direct drive based on latent heat storage
I. Voigt, S. Winkler, R. Werner, A. Bucht, W.-G. Drossel
Industrial relevance and causes of thermal issues in machine tools
M. Putz, C. Richter, J. Regel, M. BrÀunig
Clustering by optimal subsets to describe environment interdependencies
J. GlÀnzel, R. Unger, S. Ihlenfeldt
Using meta models for enclosures in machine tools
F. PavliÄek, D. P. Pamies, J. Mayr, S. ZĂŒst, P. Blaser, P. HernĂĄndez-Becerro, K. Wegener
Model order reduction of thermal models of machine tools with varying boundary conditions
P. HernĂĄndez-Becerro, J. Mayr, P. Blaser, F. PavliÄek, K. Wegener
Effectiveness of modelling the thermal behaviour of the ball screw unit with moving heat sources taken into account
J. Jedrzejewski, Z. Kowal, W. Kwasny, Z. Winiarski
Analyzing and optimizing the fluidic tempering of machine tool frames
A. Hellmich, J. GlÀnzel, A. Pierer
Thermo-mechanical interactions in hot stamping
L. Penter, N. Pierschel
Experimental analysis of the heat flux into the grinding tool in creep feed grinding with CBN abrasives
C. Wrobel, D. Trauth, P. Mattfeld, F. Klocke
Development of multidimensional characteristic diagrams for the real-time correction of thermally caused TCP-displacements in precise machining
M. Putz, C. Oppermann, M. BrÀunig
Measurement of near cutting edge temperatures in the single point diamond turning process
E. Uhlmann, D. Oberschmidt, S. Frenzel, J. Polte
Investigation of heat flows during the milling processes through infrared thermography and inverse modelling
T. Helmig, T. Augspurger, Y. Frekers, B. Döbbeler, F. Klocke, R. Kneer
Thermally induced displacements of machine tool structure, tool and workpiece due to cutting processes
O. HorejĆĄ, M. MareĆĄ, J. Hornych
A new calibration approach for a grey-box model for thermal
error compensation of a C-Axis
C. Brecher, R. Spierling, M. Fey
Investigation of passive torque of oil-air lubricated angular contact ball bearing and its modelling
J. Kekula, M. Sulitka, P. KolĂĄĆ, P. KohĂșt, J. Shim, C. H. Park, J. Hwang
Cooling strategy for motorized spindle based on energy and power criterion to reduce thermal errors
S. Grama, A. N. Badhe, A. Mathur
Cooling potential of heat pipes and heat exchangers within a machine tool spindleo
B. Denkena, B. Bergman, H. Klemme, D. Dahlmann
Structure model based correction of machine tools
X. Thiem, B. Kauschinger, S. Ihlenfeldt
Optimal temperature probe location for the compensation of transient thermal errors
G. Aguirre, J. Cilla, J. Otaegi, H. Urreta
Adaptive learning control for thermal error compensation on 5-axis machine tools with sudden boundary condition changes
P. Blaser, J. Mayr, F. PavliÄek, P. HernĂĄndez-Becerro, K. Wegener
Hybrid correction of thermal errors using temperature and deformation sensors
C. Naumann, C. Brecher, C. Baum, F. Tzanetos, S. Ihlenfeldt, M. Putz
Optimal sensor placement based on model order reduction
P. Benner, R. Herzog, N. Lang, I. Riedel, J. Saak
Workpiece temperature measurement and stabilization prior to dimensional measurement
N. S. Mian, S. Fletcher, A. P. Longstaff
Measurement of test pieces for thermal induced displacements on milling machines
H. Höfer, H. Wiemer
Model reduction for thermally induced deformation compensation of metrology frames
J. v. d. Boom
Local heat transfer measurement
A. Kuntze, S. Odenbach, W. Uffrecht
Thermal error compensation of 5-axis machine tools using a staggered modelling approach
J. Mayr, T. Tiberini. P. Blaser, K. Wegener
Design of a Photogrammetric Measurement System for Displacement and Deformation on Machine Tools
M. Riedel, J. Deutsch, J. MĂŒller. S. Ihlenfeldt
Thermography on Machine Tools
M. Riedel, J. Deutsch, J. MĂŒller, S. Ihlenfeldt
Test piece for thermal investigations of 5-axis machine tolls by on-machine measurement
M. Wiesener. P. Blaser, S. Böhl, J. Mayr, K. Wegene
Summary of Research 1994
The views expressed in this report are those of the authors and do not reflect the
official policy or position of the Department of Defense or the U.S. Government.This report contains 359 summaries of research projects which were carried out
under funding of the Naval Postgraduate School Research Program. A list of recent
publications is also included which consists of conference presentations and
publications, books, contributions to books, published journal papers, and
technical reports. The research was conducted in the areas of Aeronautics and
Astronautics, Computer Science, Electrical and Computer Engineering, Mathematics,
Mechanical Engineering, Meteorology, National Security Affairs, Oceanography,
Operations Research, Physics, and Systems Management. This also includes research
by the Command, Control and Communications (C3) Academic Group, Electronic Warfare
Academic Group, Space Systems Academic Group, and the Undersea Warfare Academic
Group