Optimal control of linear systems with time- delay and observation noise
Optimal control generated by Kalman filter and least mean-squared predictor for linear systems with time delay
Kleinman, D. L.↗
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Results for “Time Delay”
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Time delay occultation data of the Helios spacecraft for probing the electron density distribution in the solar corona
S-band time delay measurements were collected from the spacecraft Helios A and B during three solar occultations in 1975/76 within heliocentric distances of about 3 and 215 earth radius in terms of range, Doppler frequency shift, and electron content. Characteristic features of measurement and data processing are described. Typical data sets are discussed to probe the electron density distribution near the sun (west and east limb as well) including the outer and extended corona. Steady-state and dynamical aspects of the solar corona are presented and compared with earth-bound-K-coronagraph measurements. Using a weighted least squares estimation, parameters of an average coronal electron density profile are derived in a preliminary analysis to yield electron densities at r = 3, 65, 215 earth radius. Transient phenomena are discussed and a velocity of propagation v is nearly equal to 900 km/s is determined for plasma ejecta from a solar flare observed during an extraordinary set of Helios B electron content measurements.
Edenhofer, P.↗
Effect of coefficient changes on stability of linear retarded systems with constant time delays
A method is developed to determine the effect of coefficient changes on the stability of a retarded system with constant time delays. The method, which uses the tau-decomposition method of stability analysis, is demonstrated by an example.
Barker, L. K.↗
Time-delay-and-integration charge-coupled devices using tin oxide gate technology
Doped tin oxide gates are used in a time-delay-and-integration (TDI) CCD scheme in an effort to develop a stable transparent gate technology. Design characteristics of the system are discussed, including 2 sections of 10 by 9 integration stages, four-phase buried channel construction, and 10 input parallel-in/serial-out output shift register at a video rate of 1.25 MHz. A quantum efficiency of 65% with smooth spectral response is attained by front surface imaging. The suitability of the system for the Landsat program is discussed in terms of TDI-CCD operating parameters.
Thompson, L. L.↗
Software simulation of time delay in teleoperation
Research done in the Space Robotics Laboratory at the University of Atlanta at Huntsville on the effects of time delay on teleoperation is discussed. The laboratory is configured around a Puma 562 robot with 6 degrees of freedom. A custom designed joystick controller with two joysticks, each with three degrees of freedom, is used to control the robot. These joysticks are connected to the robot controller through an analog to digital interface. Joystick calibration, a computer program called Joystick, and the VAL 2 robot control language are discussed.
Goode, K. Wayne↗
Constraints on Ho from Time-Delay Measurements of PG1115+080
The observations that were performed as part of the award titled: Constraints on Ho From Time-Delay Measurements of PG1115+080 resulted in several scientific publications and presentations. We list these publications and presentations and provide brief description of the important science presented in them.
Chartas, George↗
Voyager 2 test of the radar time-delay effect
By analyzing radio range measurements generated during the solar conjunction of the Voyager 2 spacecraft in 1985, the relativistic time-delay effect has been tested accurately with a spacecraft at a distance of 3 x 10 to the 9th km from the earth. Because the range measurements were generated simultaneously at two frequencies on the downlink, it was possible to derive calibrations for the delay resulting from intervening solar plasma. In addition, a record of attitude thruster firings was used to model small accelerations of the spacecraft that could have produced a range error. It was thereby possible to determine the parameterized post-Newtonian parameter gamma to an accuracy of 3 percent with only a sparse amount of range data.
Krisher, Timothy P.↗
Estimation of nonlinear pilot model parameters including time delay.
Investigation of the feasibility of using a Kalman filter estimator for the identification of unknown parameters in nonlinear dynamic systems with a time delay. The problem considered is the application of estimation theory to determine the parameters of a family of pilot models containing delayed states. In particular, the pilot-plant dynamics are described by differential-difference equations of the retarded type. The pilot delay, included as one of the unknown parameters to be determined, is kept in pure form as opposed to the Pade approximations generally used for these systems. Problem areas associated with processing real pilot response data are included in the discussion.
Schiess, J. R.↗
Effect of additives on the ignition delay time of hypergolic propellants.
Additives effect on ignition delay and pressure of hypergolic hydrazine-nitrogen tetroxide propellant systems.
TIME DELAY↗
A ''critical'' tracking task for man-machine research related to the operators effective delay time. Part II - Experimental effects of system input spectra, control stick stiffness, and controlled element order
Closed-loop compensatory tracking for measuring operator delay time in control action
COMPENSATORY TRACKING↗
Algorithms for the determination of the time delays of the signal when using unequal detectors
In treating the recorded results from detectors at different locations in space, the analysis of the time delays of signals is crucial to locating the sources of detected radiation. Because the correlation method requires the manipulation of awkward matrices to evaluate its accuracy, a solution is outlined based on minimizing the sum of the squares of signal deviations, and the algorithms for evaluating the resulting error are presented.
Novak, B. L.↗
Effect of damping, time delays, and parameter variations on the stability of a nonconservative system
Nonconservative elastic system involving standard double pendulum model under retarded follower load, calculating damping, time delay and parameter variations effects on stability
Infante, E. F.↗
Determination of astrodynamic constants and a test of the general relativistic time delay with S-band range and Doppler data from Mariners 6 and 7
Earth/moon mass ratio and Mars mass and ephemeris from Mariners range and Doppler tracking data, noting relativistic time delay measurement possibility
Anderson, J. D.↗
Shape resonances and rotationally predissociating levels - The atomic collision time delay functions and quasibound level properties of H2/X /1 Sigma g plus//
Approximation of scattering resonance energies and widths of ground state of molecular hydrogen from energy dependence of atomic collisional time delay functions
Bernstein, R. B.↗
Microwave component time delays for the 70-meter antennas
The X-band feed assemblies in the 64 meter antennas were redesigned to accommodate the upgrading to 70 meters and the associated surface reshaping. To maintain time delay data logs, new calculations were made of the microwave component delays for the XRO Mod IV X-band (8.4 to 8.45 GHz) feed assembly that was installed at DSS-63, and will soon be implemented at DSS-43 and DSS-14.
Hartop, R.↗
Time Delay Analysis of Turbofan Engine Direct and Indirect Combustion Noise Sources
The core noise components of a dual spool turbofan engine were separated by the use of a coherence function. A source location technique based on adjusting the time delay between the combustor pressure sensor signal and the far-field microphone signal to maximize the coherence and remove as much variation of the phase angle with frequency as possible was used. The discovery was made that for the 130o microphone a 90.027 ms time shift worked best for the frequency band from 0 to 200 Hz while a 86.975 ms time shift worked best for the frequency band from 200 to 400 Hz. Hence, the 0 to 200 Hz band signal took more time than the 200 to 400 Hz band signal to travel the same distance. This suggests the 0 to 200 Hz coherent cross spectral density band is partly due to indirect combustion noise attributed to entropy fluctuations, which travel at the flow velocity, interacting with the turbine. The signal in the 200 to 400 Hz frequency band is attributed mostly to direct combustion noise. Results are presented herein for engine power settings of 48, 54, and 60 percent of the maximum power setting
Miles, Jeffrey Hilton↗
A time delay controller for magnetic bearings
The control of systems with unknown dynamics and unpredictable disturbances has raised some challenging problems. This is particularly important when high system performance needs to be guaranteed at all times. Recently, the Time Delay Control has been suggested as an alternative control scheme. The proposed control system does not require an explicit plant model nor does it depend on the estimation of specific plant parameters. Rather, it combines adaptation with past observations to directly estimate the effect of the plant dynamics. A control law is formulated for a class of dynamic systems and a sufficient condition is presented for control systems stability. The derivation is based on the bounded input-bounded output stability approach using L sub infinity function norms. The control scheme is implemented on a five degrees of freedom high speed and high precision magnetic bearing. The control performance is evaluated using step responses, frequency responses, and disturbance rejection properties. The experimental data show an excellent control performance despite the system complexity.
Youcef-Toumi, K.↗
Time-delay test of general relativity and Earth-Mars ephemeris improvement from analysis of Mariner 9 tracking data
Because of the large systematic errors that accompany the conversion of spacecraft ranging data to equivalent Earth-Mars time delays, the corresponding determination of gamma does not now allow the predictions of general relativity to be distinguished from those of the Brans-Dicke scalar-tensor theory with the fraction s of scalar field admixture being 0.06. The uncertainty in the determination of (1 plus gamma)/2 at the present stage of the Mariner 9 data analysis is at about the 10% level. The ephemeris of Mars suffers from the same problem: Only with the elimination of a major fraction of the systematic errors affecting the Mariner 9 pseudo observables will a truly substantial improvement be possible in the determination of the orbit.
Shapiro, I. I.↗