Probabilistic feedback.
Fokker-Planck equation for probability density of dynamical system under random input and probabilistic feedback applied to closed loop control systems analysis
Foy, W. H., Jr.↗
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On some further properties of nonzero-sum diffential games
Optimality principle and open loop-closed loop control relations in nonzero-sum differential games
Ho, Y. C.↗
Squared-error minimization with stability constraints.
Linear closed loop control system poorly damped response to deterministic inputs improved by stability constraint for minimization of mean squared error
Siljak, D. D.↗
Sensitivity aspects of linear digital control systems.
Linear computer-controlled closed loop systems sensitivity analysis, deriving estimation error incremental covariance to demonstrate quality deterioration under perturbed initial conditions, parameters, etc
Christie, L. A.↗
Human operator characteristics based on an analog computer oriented parameter identification technique.
Parameter identification algorithm identifying linear dynamic systems by digital computer used to identify human operator characteristics in closed loop control situation
Burgett, A. L.↗
On the minimax reachability of target sets and target tubes
Closed-loop control of discrete time systems with uncertainty, discussing minimax reachability of target sets and tubes
Bertsekas, D. P.↗
Variable sweep-rate frequency response and vibration testing
Variable sweep rate frequency response and vibration testing for test time reduction, using closed loop controller for sweep rate modulation
Lorenzo, C. F.↗
A closed loop cryogenic environment pressure regulating system
Nonlinear closed loop control system to regulate the pressure in a cryogenic environment is described. System employs four position contactor with two control bands to react to the signals. Diagrams of element transfer function and required equipment are included.
Huguley, J. C.↗
Terminal shock position and restart control of a Mach 2.7, two-dimensional, twin duct mixed compression inlet
Experimental results of terminal shock and restart control system tests of a two-dimensional, twin-duct mixed compression inlet are presented. High-response (110-Hz bandwidth) overboard bypass doors were used, both as the variable to control shock position and as the means of disturbing the inlet airflow. An inherent instability in inlet shock position resulted in noisy feedback signals and thus restricted the terminal shock position control performance that was achieved. Proportional-plus-integral type controllers using either throat exit static pressure or shock position sensor feedback gave adequate low-frequency control. The inlet restart control system kept the terminal shock control loop closed throughout the unstart-restart transient. The capability to restart the inlet was non limited by the inlet instability.
Cole, G. L.↗
A hollow cathode neutralizer for a 30-cm diameter bombardment thruster
Recent improvements in overall thruster performance have imposed new constraints on neutralizer performance. The use of compensated grid extraction system requires a reevaluation of neutralizer position. A series of tests were conducted to determine what effect neutralizer cathode geometry has on performance. The parameters investigated included orifice diameter and length, and cathode diameter. Similar tests investigated open and enclosed keeper geometries. Neutralizer position tests with compensated grids suggested positions approximately 10 cm from the accelerator and radially out of the beam envelope should result in satisfactory performance and long life. Operation at keeper current of 1.5 am resulted in lower total neutralizer power, the elimination of tip heater power, and suitable closed loop control of the neutralizer vaporizer.
Bechtel, R. T.↗
Zone generator for Large Space Telescope technology
A concept is presented for monitoring the optical adjustment and performance of a Large Space Telescope which consists of a 1.2m diameter turntable with a laser stylus to operate at speeds up to 30 rpm. The focus of the laser stylus is under closed loop control. A technique for scribing zones of suitable depth, width, and uniformity applicable to large telescope mirrors is also reported.
Erickson, K. E.↗
Stepping optical path difference in an interferometer
Stepping method permits higher amplitude modulation of secondary mirror of Fourier interferometer. Amplitude of mirror motion is limited only by available voltage drive on error-correcting actuator. Closed-loop controller provides servo error voltage linearly proportional to offset from proper null position. Bidirectional counter serves to count number of reference laser fringes offset from null position.
Schindler, R. A.↗
Shuttle/tethered satellite system conceptual design study
A closed-loop control system was added to the tether reel which improves control over the tethered satellite. In addition to increasing the stability of the tethered satellite along local vertical, this control system is used for deployment and retrieval of tethered satellites. This conceptual design study describes a tether system for suspending a science payload at an altitude of 120 km from space shuttle orbiter flying at an altitude of 200 km. In addition to the hardware conceptual designs, various aspects concerning Orbiter accommodations are discussed.
Source record↗
Demand-type gas supply system for rocket borne thin-window proportional counters
A simple closed loop control system has been developed to maintain the gas pressure in thin-window proportional counters during rocket flights. This system permits convenient external control of detector pressure and system flushing rate. The control system is activated at launch with the sealing of a reference volume at the existing system pressure. Inflight control to plus or minus 2 torr at a working pressure of 760 torr has been achieved on six rocket flights.
Acton, L. W.↗
Shuttle/tethered satellite system
A tethered satellite system has been conceived as a device to extend the capability of the Space Shuttle to perform scientific/applications investigations and operational activities. The concept envisions a multiple-use tethered system with closed-loop control, capable of supporting a payload or satellite suspended from the Shuttle cargo bay, toward or away from the earth, at distances up to 100 kilometers from the Shuttle. This paper discusses the background and results of early analyses and feasibility studies, and presents a design and operational description of the system. Also presented are a discussion of potential applications of the Tethered Satellite System, and plans for an operational verification flight in 1982.
Rupp, C. C.↗
A preference-ordered discrete-gaming approach to air-combat analysis
An approach to one-on-one air-combat analysis is described which employs discrete gaming of a parameterized model featuring choice between several closed-loop control policies. A preference-ordering formulation due to Falco is applied to rational choice between outcomes: win, loss, mutual capture, purposeful disengagement, draw. Approximate optimization is provided by an active-cell scheme similar to Falco's obtained by a 'backing up' process similar to that of Kopp. The approach is designed primarily for short-duration duels between craft with large-envelope weaponry. Some illustrative computations are presented for an example modeled using constant-speed vehicles and very rough estimation of energy shifts.
Kelley, H. J.↗
Correlation tracking for a Planetary Pointing and Tracking System
The Planetary Pointing and Tracking System (PPTS) is being developed to provide precision pointing for science platforms on future autonomous planetary spacecraft. The PPTS design approach using a CCD optical sensor for closed-loop control with respect to the target body, a gyro for inertial stabilization, and brushless dc torque motors for smooth and continuous platform articulation is essential for high resolution planetary imaging and automated science execution. An integral part of PPTS is the correlation tracker which has the potential to revolutionize autonomous guidance.
Assefi, T.↗
A laboratory facility for electric vehicle propulsion system testing
The road load simulator facility located at the NASA Lewis Research Center enables a propulsion system or any of its components to be evaluated under a realistic vehicle inertia and road loads. The load is applied to the system under test according to the road load equation: F(net)=K1F1+K2F2V+K3 sq V+K4(dv/dt)+K5 sin theta. The coefficient of each term in the equation can be varied over a wide range with vehicle inertial representative of vehicles up to 7500 pounds simulated by means of flywheels. The required torque is applied by the flywheels, a hydroviscous absorber and clutch, and a drive motor integrated by a closed loop control system to produce a smooth, continuous load up to 150 horsepower.
Sargent, N. B.↗