The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
T.c. Bossart - One of the best experts on this subject based on the ideXlab platform.
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Exact feedback linearization and control of space station using CMG
IEEE Transactions on Automatic Control, 1993Co-Authors: S.n. Singh, T.c. BossartAbstract:Based on feedback linearization theory, an approach to attitude control of a space station using control moment gyros (CMGs) is developed. A linearizing transformation is derived to obtain a simple linear representation of the nonlinear pitch Axis dynamics. A feedback control law for trajectory tracking is derived. Extension of this approach to linearization of the coupled yaw and Roll Axis dynamics and control is presented.
Rajendra Singh - One of the best experts on this subject based on the ideXlab platform.
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Enhanced Motion Control of Powertrain Using a Combination of Active and Passive Mounts
Volume 2: Diagnostics and Detection; Drilling; Dynamics and Control of Wind Energy Systems; Energy Harvesting; Estimation and Identification; Flexible, 2015Co-Authors: Jared Liette, Rajendra SinghAbstract:Vibration control of a realistic coupled powertrain and frame system is analytically and computationally studied using a combination of active and passive mounts. Actuators are placed in the powertrain paths for active control, and passive mounts are employed such that the powertrain Roll motion is dominant using the torque Roll Axis motion decoupling concept. To facilitate this study, a new 24 degree of freedom mathematical model for a coupled powertrain and frame is developed with versatility where passive only, active only, or combined active and passive powertrain paths can be selected. Active control forces are defined as constant, real valued amplitudes to counteract the dominate powertrain Roll motion. Alternate path models are then quantitatively compared based on the global powertrain motion magnitudes. It is found that superior vibration control is achieved with combined paths, provided all powertrain paths are aligned with the torque Roll Axis coordinates. Additionally, successful control is dependent on which paths are selected as a combination of active and passive mounts, dictated by the interaction between active control forces and the passive system dynamics.Copyright © 2015 by ASME
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critical examination of isolation system design paradigms for a coupled powertrain and frame partial torque Roll Axis decoupling methods given practical constraints
Journal of Sound and Vibration, 2014Co-Authors: Jared Liette, Jason T Dreyer, Rajendra SinghAbstract:Abstract The torque Roll Axis motion decoupling concept is analytically and computationally studied in a realistic coupled powertrain and frame system using discrete, proportionally damped linear models. Recently, Hu and Singh (2012 [1] ) (Journal of Sound and Vibration 331 (2012) 1498–1518) proposed new paradigms to fully decouple such a system. However, critical examination shows that the derivation does not always lead to a physically realizable system, as each powertrain mount is not referenced to a single location. This deficiency is overcome by deriving mount compatibility conditions to ensure realistic mount positions which are incorporated into proposed decoupling conditions. It is mathematically shown that full decoupling is not possible for a practical system, and therefore partial decoupling paradigms are pursued. Powertrain mount design using only the decoupled powertrain achieves better decoupling than minimizing conditions for the coupled system using a total least squares method. Further decoupling is obtained through frame isolation design using a decoupled frame model such that the torque Roll mode is dominant over the frequency range considered. Other methods for limiting frame coupling are also briefly discussed.
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improved torque Roll Axis decoupling axiom for a powertrain mounting system in the presence of a compliant base
Journal of Sound and Vibration, 2012Co-Authors: Jinfang Hu, Rajendra SinghAbstract:Abstract The existing torque Roll Axis decoupling theories for powertrain mounting systems assume a rigid foundation, thus ignoring dynamic interactions between the powertrain and other sub-systems. To overcome this deficiency, a coupled mounting system problem is formulated based on the linear time-invariant system theory. The influence of a compliant base on torque Roll Axis decoupling is first analytically examined in terms of eigensolutions and frequency responses. Then, a new analytical axiom is proposed based on decoupling indices as well as given the properties of the coupling matrix. Five examples are chosen to examine frequency and time domain responses given the torque excitation along the crankshaft Axis. To satisfy the new condition, the mounting system is redesigned in terms of the stiffness rates, mount locations, and orientation angles. The results show that the torque Roll Axis of the redesigned powertrain mounting system is indeed decoupled in the presence of a compliant base (given oscillating or impulsive torque excitation). Finally, eigensolutions are validated by using published data.
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effect of non proportional damping on the torque Roll Axis decoupling of an engine mounting system
Journal of Sound and Vibration, 2008Co-Authors: Jaeyeol Park, Rajendra SinghAbstract:Several mounting system design concepts are conceptually used to decouple the engine Roll mode though limited success has been observed in practice. One shortcoming of the existing theories or design methods is that they ignore non-proportional viscous damping in their formulations. It seems that the rigid-body vibrations are coupled whenever non-proportional damping is introduced to the mounting system even though the torque Roll Axis decoupling is still theoretically possible with proportional damping assumption. To overcome this deficiency, we re-formulate the problem for a non-proportionally damped linear system while recognizing that significant damping may be possible with passive (such as hydraulic) or adaptive mounts. The complex mode method is employed in our work and the torque Roll Axis decoupling paradigm is re-examined given mount rate ratios, mount locations and orientation angles as key design parameters. We derive a necessary axiom for a mode in the torque Roll Axis direction provided two eigenvalue problems, in terms of stiffness and damping matrices, are concurrently satisfied. Two numerical examples are chosen to examine both steady-state and transient responses and the extent of coupling or decoupling is quantified. Results show that the torque Roll Axis for a mounting system with non-proportional damping (under oscillating torque excitation) is indeed decoupled when one of the damped modes lies in the torque Roll Axis direction. Finally, eigensolutions are validated by using experimental data.
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analytical methods of decoupling the automotive engine torque Roll Axis
Journal of Sound and Vibration, 2000Co-Authors: Taeseok Jeong, Rajendra SinghAbstract:Abstract This paper analytically examines the multi-dimensional mounting schemes of an automotive engine–gearbox system when excited by oscillating torques. In particular, the issue of torque Roll Axis decoupling is analyzed in significant detail since it is poorly understood. New dynamic decoupling axioms are presented an d compared with the conventional elastic Axis mounting and focalization methods. A linear time-invariant system assumption is made in addition to a proportionally damped system. Only rigid-body modes of the powertrain are considered and the chassis elements are assumed to be rigid. Several simplified physical systems are considered and new closed-form solutions for symmetric and asymmetric engine-mounting systems are developed. These clearly explain the design concepts for the 4-point mounting scheme. Our analytical solutions match with the existing design formulations that are only applicable to symmetric geometries. Spectra for all six rigid-body motions are predicted using the alternate decoupling methods and the closed-form solutions are verified. Also, our method is validated by comparing modal solutions with prior experimental and analytical studies. Parametric design studies are carried out to illustrate the methodology. Chief contributions of this research include the development of new or refined analytical models and closed-form solutions along with improved design strategies for the torque Roll Axis decoupling.
S.n. Singh - One of the best experts on this subject based on the ideXlab platform.
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Exact feedback linearization and control of space station using CMG
IEEE Transactions on Automatic Control, 1993Co-Authors: S.n. Singh, T.c. BossartAbstract:Based on feedback linearization theory, an approach to attitude control of a space station using control moment gyros (CMGs) is developed. A linearizing transformation is derived to obtain a simple linear representation of the nonlinear pitch Axis dynamics. A feedback control law for trajectory tracking is derived. Extension of this approach to linearization of the coupled yaw and Roll Axis dynamics and control is presented.
Dominik Straumann - One of the best experts on this subject based on the ideXlab platform.
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Otolith testing: Roll plane disorders
Vertigo and Imbalance: Clinical Neurophysiologyof the Vestibular System, 2009Co-Authors: Antonella Palla, Dominik Straumann, Alexander A. TarnutzerAbstract:Publisher Summary This chapter discusses that the Roll plane of the upright positioned head is oriented earth-vertical and forms a right angle with the sagittal plane. In a comfortable sitting position, Reid's plane, that is the line between the lower rim of the orbita and the center of the external auditory canal, is tilted upward by about 20°. In this position, the Roll Axis of the head is earthhorizontal and bisects the interaural line, while the Roll axes of the eyes are earth-horizontal as well, but passes through the center of the respective ocular globe. It reviews that rotation about the naso-occipital Axis is used synonymously to rotation about the Roll Axis or rotation in the Roll plane. Head tilt, on the other hand, is not necessarily restricted to the Roll plane, since the head can also be tilted in the pitch plane. The chapter concentrates on head Roll with the rotation Axis oriented earth-horizontally. Two principal phenomena related to this type of head Roll have been studied extensively: The Rolling of the eyes in the opposite direction of head Roll, called ocular counterRoll and the Roll-dependent perception of earth-verticality in the absence of visual cues, called subjective vertical. It also discusses the recording techniques, the physiology, and the pathophysiology, including specific disorders of both the phenomena.
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vertical divergence and counterRoll eye movements evoked by whole body position steps about the Roll Axis of the head in humans
Journal of Neurophysiology, 2001Co-Authors: A A Kori, A Schmidpriscoveanu, Dominik StraumannAbstract:In healthy human subjects, a head tilt about its Roll Axis evokes a dynamic counterRoll that is mediated by both semicircular canal and otolith stimulation, and a static counterRoll that is mediate...
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Vertical divergence and counterRoll eye movements evoked by whole-body position steps about the Roll Axis of the head in humans.
Journal of Neurophysiology, 2001Co-Authors: A A Kori, A. Schmid-priscoveanu, Dominik StraumannAbstract:In healthy human subjects, a head tilt about its Roll Axis evokes a dynamic counterRoll that is mediated by both semicircular canal and otolith stimulation, and a static counterRoll that is mediated by otolith stimulation only. The vertical ocular divergence associated with the static counterRoll too is otolith-mediated. A previous study has shown that, in humans, there is also a vertical divergence during dynamic head Roll, but this report was not conclusive on whether this response was mediated by the semicircular canals only or whether the otoliths made a significant contribution. To clarify this issue, we applied torsional whole-body position steps (amplitude 10°, peak acceleration of 90°/s2, duration 650 ms) about the earth-vertical (supine body position) and earth-horizontal (upright body position) Axis to healthy human subjects who were monocularly fixating a straight-ahead target. Eye movements were recorded binocularly with dual search coils in three dimensions. The dynamic parameters were determ...
David Alais - One of the best experts on this subject based on the ideXlab platform.
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serial dependence in face attractiveness judgements tolerates rotations around the yaw Axis but not the Roll Axis
Visual Cognition, 2016Co-Authors: Jessica Taubert, David AlaisAbstract:ABSTRACTOnce a face is detected, its retinal image will be continually distorted by changes in eye position, noise, lighting and many other factors. Yet from one moment to the next our perception of a face is stable. Recent advances have indicated there is a mechanism for achieving the continuous perception of a person’s identity that pools across prior and present visual inputs. There is still debate as to whether the perception of face attractiveness is also serially dependent. Here we investigate continuity in the perception of attractiveness using a one back [t−1] effect as a marker of serial dependence. Our results show that face attractiveness is biased towards the attractiveness of the previous face, and that this effect is robust despite changes in viewpoint involving rotations around the yaw Axis. However, face attractiveness perception is released from this form of rapid adaption when the previously seen face differed in orientation due to a rotation around the Roll Axis.
