This paper is concerned with the stability of carbon fiber sail structures that are being studied in a series of experiments at the Jet Propulsion Laboratory (JPL) by a team led by Microwave Sciences, Inc. The passive...
This paper is concerned with the stability of carbon fiber sail structures that are being studied in a series of experiments at the Jet Propulsion Laboratory (JPL) by a team led by Microwave Sciences, Inc. The passive dynamic stability in the one-dimensional (1-D) case is most easily understood in terms of the fixed points of the trajectories for the governing equations of motion. The simple 1-D model introduces the possibility of controlling a microwave-propelled sail using various nonlinear control strategies. This work will be extended in the future to control the full 3-D case. We present results of studies from the 1-D analysis. In addition to providing guidance to ongoing and near term proof-of-principle experiments, this work will lead to novel strategies for enabling a feedback power controller to maintain a sail fixed at a predetermined height.
We report the results of thermal wave measurements of corrosion thinning on painted metal aircraft belly skins. We have developed algorithms to compensate for irregular variations in paint thickness. These algorithms ...
We report the results of thermal wave measurements of corrosion thinning on painted metal aircraft belly skins. We have developed algorithms to compensate for irregular variations in paint thickness. These algorithms have been successfully blind-tested on a DC-9 belly skin.
Magneto-optic imaging (MOI) is a relatively new sensor application of an extension of bubble memory technology to NDT and produce easy-to-interpret, real time analog images. MOI systems use a magneto-optic (MO) sensor...
Magneto-optic imaging (MOI) is a relatively new sensor application of an extension of bubble memory technology to NDT and produce easy-to-interpret, real time analog images. MOI systems use a magneto-optic (MO) sensor to produce analog images of magnetic flux leakage from surface and subsurface defects. The instrument’s capability in detecting the relatively weak magnetic fields associated with subsurface defects depends on the sensitivity of the magneto-optic sensor. The availability of a theoretical model that can simulate the MOI system performance is extremely important for optimization of the MOI sensor and hardware system. A nodal finite element model based on magnetic vector potential formulation has been developed for simulating MOI phenomenon. This model has been used for predicting the magnetic fields in simple test geometry with corrosion dome defects. In the case of test samples with multiple discontinuities, a more robust model using the magnetic vector potential Ā and electrical scalar potential V is required. In this paper, a finite element model based on A−V formulation is developed to model complex circumferential crack under aluminum rivets in dimpled countersink.
Repetitive processes are a distinct class of 2D systems of both theoretical and applications interest. They are characterized by a series of sweeps through a set of dynamics with explicit interaction between the outpu...
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Repetitive processes are a distinct class of 2D systems of both theoretical and applications interest. They are characterized by a series of sweeps through a set of dynamics with explicit interaction between the outputs, or pass profiles, produced on successive passes. Their essential unique features are that (i) information propagation is over a finite duration in one of the two separate directions of information propagation; and (ii) the explicit interaction between successive pass profiles can lead to oscillations in the sequence of pass profiles that increase in amplitude in the pass to pass direction. In the case of processes with linear dynamics (either differential or discrete) a reasonably rich systems theory is available for models which are standard (or nonsingular). In this paper, we provide the first substantial results on discrete linear repetitive processes described by a singular state space model.
The extended Kalman filter is known to have excellent filtering characteristics, but its convergence is guaranteed only if it is initialized close enough to the true state value. Numerical differentiation based observ...
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An electromagnetic-type vibratory feeder of is a typical transportation device used in automatic weighers. As existing feeders are driven by feedforward control, the so-called "firing angle control", the dri...
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An electromagnetic-type vibratory feeder of is a typical transportation device used in automatic weighers. As existing feeders are driven by feedforward control, the so-called "firing angle control", the driver cannot negate sudden disturbances. In this study, we consider applying a feedback control for such a feeder system. First, we give the two details of modelings for the vibration part and for the electromagnetic force part. Next, a feedback control system is constructed for the electromagnetic vibration feeder for which we propose a two-degrees-of-freedom proportional plus integral plus derivative (PID) controller with nonlinear elements. Next, we apply the feedback control to the feeder with a standard trough. Finally, we consider a method compatible with many varieties of troughs by adjusting a nonlinear element. On the basis of the results of some experiments, we confirm that the two-degrees-of-freedom PID control is more effective than the conventional firing angle control.
Bluetooth is currently emerging as one of the most promising personal wireless network technologies. The automation industry is also showing interest in using Bluetooth for more industrial applications. However, probl...
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Bluetooth is currently emerging as one of the most promising personal wireless network technologies. The automation industry is also showing interest in using Bluetooth for more industrial applications. However, problems with unreliable links and time delays must be explicitly addressed in any wireless control application. This paper discusses two specific problems that may occur when using Bluetooth in a control loop: long random delays and bit errors. Simple solutions to these problems are presented. The ideas have been tried out, both in simulations and in experiments, on a rotating inverted pendulum controlled over a Bluetooth network.
This paper discusses the three-dimensional (3-D) stability of carbon fiber sail structures (beam riders) that are being studied in a series of experiments at the Jet Propulsion Laboratory (JPL) and U.C. Irvine by a te...
This paper discusses the three-dimensional (3-D) stability of carbon fiber sail structures (beam riders) that are being studied in a series of experiments at the Jet Propulsion Laboratory (JPL) and U.C. Irvine by a team led by Microwave Sciences, Inc. The stability analysis is developed for a limited set of conical sail configurations, and the code described in this paper has been developed at JPL by one of the coauthors. The assumptions in the model and the principles behind the simulation, in addition to their relationship to earlier experiments utilizing disk configurations are discussed. Results of stability analyses for several beam rider configurations will be presented at the Forum.
作者：
F. PlestanJ.W. GrizzleE.R. WesterveltG. AbbaIRCCyN
Ecole Centrale Université et Ecole des Mines de Nantes CNRS BP 92101 1 rue de la Noë 44321 Nantes cedex 03 France Control Systems Laboratory
Electrical Engineering and Computer Science Department University of Michigan Ann Arbor MI 48109-2122 USA LGIPM
Université de Metz IUT de Thionville Espace Cormontaigne 57970 Yutz France
The goal is to demonstrate a means to prove asymptotically stable walking in a planar, under actuated, five-link biped robot model. The analysis assumes a rigid contact model when the swing leg impacts the ground and ...
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The goal is to demonstrate a means to prove asymptotically stable walking in a planar, under actuated, five-link biped robot model. The analysis assumes a rigid contact model when the swing leg impacts the ground and an instantaneous double-support phase: under theses hypotheses, the robot is modeled by a dynamic nonlinear system and an impulse model. The controller induces finite-time stabilization of four of the robot's five degrees of freedom, resulting in a reduced Poincaré stability analysis that can be carried out by computing a one dimensional map.
Micro-Raman spectroscopy of an isolated single wall carbon nanotube is overviewed in connection with the recent observation of (1) the chirality-dependent G-band Raman intensity, (2) BWF line analysis and (3) D-band f...
Micro-Raman spectroscopy of an isolated single wall carbon nanotube is overviewed in connection with the recent observation of (1) the chirality-dependent G-band Raman intensity, (2) BWF line analysis and (3) D-band feature of an individual single wall carbon nanotube. The localized phonons appeared around a point defect of carbon nanotube might be relevant to D-band intensity.
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