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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Computer controlled antenna system

The application of small computers using digital techniques for operating the servo and control system of large antennas is discussed. The advantages of the system are described. The techniques were evaluated with a forty foot antenna and the Sigma V computer. Programs have been completed which drive the antenna directly without the need for a servo amplifier, antenna position programmer or a scan generator.

Raumann, N. A.↗
NASA NTRS2008

Small Autonomous Aircraft Servo Health Monitoring

Small air vehicles offer challenging power, weight, and volume constraints when considering implementation of system health monitoring technologies. In order to develop a testbed for monitoring the health and integrity of control surface servos and linkages, the Autonomous Aircraft Servo Health Monitoring system has been designed for small Uninhabited Aerial Vehicle (UAV) platforms to detect problematic behavior from servos and the air craft structures they control, This system will serve to verify the structural integrity of an aircraft's servos and linkages and thereby, through early detection of a problematic situation, minimize the chances of an aircraft accident. Embry-Riddle Aeronautical University's rotary-winged UAV has an Airborne Power management unit that is responsible for regulating, distributing, and monitoring the power supplied to the UAV's avionics. The current sensing technology utilized by the Airborne Power Management system is also the basis for the Servo Health system. The Servo Health system measures the current draw of the servos while the servos are in Motion in order to quantify the servo health. During a preflight check, deviations from a known baseline behavior can be logged and their causes found upon closer inspection of the aircraft. The erratic behavior nay include binding as a result of dirt buildup or backlash caused by looseness in the mechanical linkages. Moreover, the Servo Health system will allow elusive problems to be identified and preventative measures taken to avoid unnecessary hazardous conditions in small autonomous aircraft.

Quintero, Steven↗
NASA NTRS1982

Programmable controller system for wind tunnel diversion vanes

A programmable controller (PC) system automatic sequence control, which acts as a supervisory controller for the servos, selects the proper drives, and automatically sequences the vanes, was developed for use in a subsonic wind tunnel. Tunnel modifications include a new second test section (80 ft x 100 ft with a maximum air speed capability of 110 knots) and an increase in maximum velocity flow from 200 knots to 300 knots. A completely automatic sequence control is necessary in order to allow intricate motion of the 14 triangularly arranged vanes which can be as large as 70 ft high x 35 ft wide and which require precise acceleration and deceleration control. Rate servos on each drive aid in this control, and servo cost was minimized by using four silicon controlled rectifier controllers to control the 20 dc drives. The PC has a programming capacity which facilitated the implementation of extensive logic design. A series of diagrams sequencing the vanes and a block diagram of the system are included.

King, R. F.↗
NASA NTRS1977

Magnetic bearing momentum wheels with magnetic gimballing capability for 3-axis active attitude control and energy storage

Magnetic bearings used for the suspension of momentum wheels provide conclusive advantages: the low friction torques and the absence of abrasion allow the realization of lightweight high speed wheels with high angular momentum and energy storage capacity and virtually unlimited lifetime. The use of actively controlled bearings provides a magnetic gimballing capability by applying the external signals to the two servo loops controlling the rotational degrees of freedom. Thus, an attitude control system can be realized by using only one rotating mass for 3-axis active satellite stabilization.

Sindlinger, R. S.↗
NASA NTRSDate not supplied

Design of a Thrust Vector Servoelastic Filter for SLS Block 2 Booster Thrust Vector Control System

This paper presents a method to improve the thrust vector servoelastic (TVSE) response of a launch vehicle. TVSE is the coupling between the Thrust Vector Control (TVC) system nozzle dynamics and the vehicle flexible modes. A poorly phased TVC response, i.e. in phase with the structural velocity, can lead to instability of the flexible modes due to the energy injection from the thrust. For large boosters with heavy nozzles, TVSE is more likely to cause instability. This instability is part of the plant dynamics and may not be readily detected by the flight control system. In this paper, TVSE is treated as a disturbance rejection problem with the inertial force of the flexible motion viewed as an external disturbance to the TVC actuator control system. By effectively rejecting this disturbance, the engine can be decoupled from the flexible dynamics thus improving TVSE stability. The actuator disturbance transfer function is modified by inserting a filter into the servo-loop control system. The filter aims to reduce the magnitude and introduce phase lead of the disturbance transfer function over the TVSE sensitive frequency range while maintaining adequate stability margins of the actuator control system. A prefilter is also designed to improve command tracking performance. The filter and prefilter resulting from this method are usually of low order and can be included to an existing actuator controller if the controller is programmable. This method was demonstrated for a hydraulic Simplex actuator model. Its applications to the Space Launch System (SLS) Block 1 and Block 2 TVC actuator are also described. The Block 2 actuator controller was modified based on the results of this method. The tradeoff between TVSE stability and the servo-loop stability can be balanced by adjusting the amount of phase lead introduced by the TVSE filter. This method provides a useful way to solve the TVSE instability issue without costly and time-consuming hardware solutions. This method is based on the basic control principles of loop shaping and disturbance rejection and has been proven to be effective under proper circumstances.

Thrust vector control↗
NASA NTRS1973

Analysis of the computed torque drive method and comparison with conventional position servo for a computer-controlled manipulator

A manipulator and its control system (modeled after a Stanford design) is being developed as part of an artificial intelligence project. This development includes an analytical study of the control system software. A comparison is presented of the computed torque method and the conventional position servo. No conclusion is made as to the perference of one system over the other, as it is dependent upon the application and the results of a sampled data analysis.

Markiewicz, B. R.↗
NASA NTRS2005

Reconfigurable Flight Control Design using a Robust Servo LQR and Radial Basis Function Neural Networks

This viewgraph presentation reviews the use of a Robust Servo Linear Quadratic Regulator (LQR) and a Radial Basis Function (RBF) Neural Network in reconfigurable flight control designs in adaptation to a aircraft part failure. The method uses a robust LQR servomechanism design with model Reference adaptive control, and RBF neural networks. During the failure the LQR servomechanism behaved well, and using the neural networks improved the tracking.

Burken, John J.↗
NASA NTRS1992

Autonomous Space Processor for Orbital Debris (ASPOD)

A project in the Advanced Design Program at the University of Arizona is described. The project is named the Autonomous Space Processor for Orbital Debris (ASPOD) and is a Universities Space Research Association (USRA) sponsored design project. The development of ASPOD and the students' abilities in designing and building a prototype spacecraft are the ultimate goals of this project. This year's focus entailed the development of a secondary robotic arm and end-effector to work in tandem with an existent arm in the removal of orbital debris. The new arm features the introduction of composite materials and a linear drive system, thus producing a light-weight and more accurate prototype. The main characteristic of the end-effector design is that it incorporates all of the motors and gearing internally, thus not subjecting them to the harsh space environment. Furthermore, the arm and the end-effector are automated by a control system with positional feedback. This system is composed of magnetic and optical encoders connected to a 486 PC via two servo-motor controller cards. Programming a series of basic routines and sub-routines allowed the ASPOD prototype to become more autonomous. The new system is expected to perform specified tasks with a positional accuracy of 0.5 cm.

Ramohalli, Kumar↗
NASA NTRS1992

Autonomous space processor for orbital debris advanced design project in support of solar system exploration

This paper is regarding a project in the Advanced Design Program at the University of Arizona. The project is named the Autonomous Space Processor for Orbital Debris (ASPOD) and is a NASA/Universities Space Research Association (USRA) sponsored design project. The development of ASPOD and the students' abilities in designing and building a prototype spacecraft are the ultimate goals of this project. This year's focus entailed the development of a secondary robotic arm and end-effector to work in tandem with an existent arm in the removal of orbital debris. The new arm features the introduction of composite materials and a linear drive system, thus producing a light-weight and more accurate prototype. The main characteristic of the end-effector design is that it incorporates all of the motors and gearing internally, thus not subjecting them to the harsh space environment. Furthermore, the arm and the end-effector are automated by a control system with positional feedback. This system is composed of magnetic and optical encoders connected to a 486 PC via two servo-motor controller cards. Programming a series of basic routines and sub-routines has allowed the ASPOD prototype to become more autonomous. The new system is expected to perform specified tasks with a positional accuracy of 0.5 cm.

Ramohalli, Kumar↗
NASA NTRS1999

Modeling and Validation of a Navy A6-Intruder Actively Controlled Landing Gear System

Concepts for long-range air travel are characterized by airframe designs with long, slender, relatively flexible fuselages. One aspect often overlooked is ground-induced vibration of these aircraft. This paper presents an analytical and experimental study of reducing ground-induced aircraft vibration loads by using actively controlled landing gear. A facility has been developed to test various active landing gear control concepts and their performance, The facility uses a Navy A6 Intruder landing gear fitted with an auxiliary hydraulic supply electronically controlled by servo valves. An analytical model of the gear is presented, including modifications to actuate the gear externally, and test data are used to validate the model. The control design is described and closed-loop test and analysis comparisons are presented.

Horta, Lucas G.↗