Engineering topics

Mettler, Edward

Publications and source records attributed to Mettler, Edward.

25 records · Page 2

NASA NTRS1991

System Would Keep Telescope Reflector Segments Aligned

Proposed actuation system maintains alignments of reflector segments of large telescope. Sensors measure positions and orientations of segments. Figure-control computer calculates orientation and figure of overall reflector surface from sensor data. Responding to computer output, servocontroller for each actuator corrects piston and tilt errors of each segment. Actuators adjust segments in response to sensed positions. Concept applicable to such large segmented space-based reflectors as those used in communication and in collection of solar energy.

Mettler, Edward↗

NASA NTRS1990

Autonomous-Control Concept For Instrument Pointing System

Integrated payload articulation and identification system (IPAIDS) is conceptual system to control aiming of instruments aboard spacecraft of proposed Earth Observation System (EOS). Principal features of concept include advanced control strategies intended to assure robustness of performance over wide range of uncertainties in characteristics of spacecraft and instrument system. Intended originally for application to spacecraft system, has potential utility on Earth for automatic control of autonomous (robotic) vehicles or of remote sensing systems.

Mettler, Edward↗

NASA NTRS1988

Technologies for antenna shape and vibration control

This paper describes the application of advanced control methods and techniques to the second- and third-generation mobile satellite (MSAT) configurations having wrap-rib offset feed construction. The technologies are generically applicable to other designs such as hoop-column and other elastically deformable non-rigid structures. The focus of the discussion is on reflector shape determination and control, dynamics identification, and pointing jitter suppression.

Mettler, Edward↗

NASA NTRS1988

EOS integrated payload articulation and identification system

This paper describes an autonomous control concept for pointing and articulation of science instruments on the EOS NASA/NOAA platforms intended to be operational by the late 1990s. Key features of this concept include advanced control adaptation and tuning strategies which provide performance robustness over a wide range of system uncertainties and mission time criticality. System identification-control modification paradigms are synthesized to form an adaptation continuum over this extended regime of autonomous operations.

Mettler, Edward↗

NASA NTRS1988

On-orbit system identification overview

Parameter identification and modeling are key elements of a design and operational flight strategy for control of flexible space structures. The emphasis of the identification program is on on-orbit applications to spacecraft control. High performance robust controllers will result from advanced design synthesis techniques and on-orbit identification/system tuning. Near term goals for the program include development of an integrated on-line processing capability for flexible body parameter identification, and validation with physical structure experiments.

Mettler, Edward↗

NASA NTRS1988

Identification and control integration strategies

This paper describes an autonomous control concept for pointing and articulation of science instruments on the Eos (Earth observing system) NASA/NOAA platforms intended to be operational by the late 1990s. Key features of this concept include advanced control adaptation and tuning strategies which provide performance robustness over a wide range of system uncertainties and mission time criticality. System identification-control modification paradigms are synthesized to form an adaptation continuum over this extended regime of autonomous operations.

Milman, Mark↗

NASA NTRS1986

System identification for modeling for control of flexible structures

The major components of a design and operational flight strategy for flexible structure control systems are presented. In this strategy an initial distributed parameter control design is developed and implemented from available ground test data and on-orbit identification using sophisticated modeling and synthesis techniques. The reliability of this high performance controller is directly linked to the accuracy of the parameters on which the design is based. Because uncertainties inevitably grow without system monitoring, maintaining the control system requires an active on-line system identification function to supply parameter updates and covariance information. Control laws can then be modified to improve performance when the error envelopes are decreased. In terms of system safety and stability the covariance information is of equal importance as the parameter values themselves. If the on-line system ID function detects an increase in parameter error covariances, then corresponding adjustments must be made in the control laws to increase robustness. If the error covariances exceed some threshold, an autonomous calibration sequence could be initiated to restore the error enveloped to an acceptable level.

Mettler, Edward↗