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NASA NTRS1987

Large space structures - Structural concepts and materials

Large space structures will be a key element of the future space activities. They will include spacecraft such as the planned Space Station and large antenna/reflector structures for communications and observations. These large structures will exceed 100 m in length or 30 m in diameter. Concepts for construction of these spacecraft on orbit and their materials of construction provide some unique research challenges. This paper will provide an overview of the research in space construction of large structures including erectable and deployable concepts. Also, an approach to automated, on-orbit construction will be presented. Materials research for space applications focuses on high stiffness, low expansion composite materials that provide adequate durability in the space environment. The status of these materials research activities will be discussed.

Blankenship, Charles P.↗

NASA NTRS1988

Vibration suppression in a large space structure

The Yale University Center for Systems Science and the NASA Johnson Space Center collaborated in a study of vibration suppression in a large space structure during the period January 1985 to August 1987. The research proposal submitted by the Center to NASA concerned disturbance isolation in flexible space structures. The general objective of the proposal was to create within the Center a critical mass of expertise on problems related to the dynamics and control of large flexible space structures. A specific objective was to formulate both passive and active control strategies for the disturbance isolation problem. Both objectives were achieved during the period of the contract. While an extensive literature exists on the control of flexible space structures, it is generally acknowledged that many important questions remain open at even a fundamental level. Hence, instead of studying grossly simplified models of complex structural systems, it was decided as a first step to confine attention to detailed and thorough analyses of simple structures.

Narendra, Kumpati S.↗

NASA NTRS1984

Definition of technology development missions for early space stations. Large space structures, phase 2, midterm review

The large space structures technology development missions to be performed on an early manned space station was studied and defined and the resources needed and the design implications to an early space station to carry out these large space structures technology development missions were determined. Emphasis is being placed on more detail in mission designs and space station resource requirements.

Source record↗

NASA NTRS1994

Experimental validation of an integrated controls-structures design methodology for a class of flexible space structures

This paper describes the first experimental validation of an optimization-based integrated controls-structures design methodology for a class of flexible space structures. The Controls-Structures-Interaction (CSI) Evolutionary Model, a laboratory test bed at Langley, is redesigned based on the integrated design methodology with two different dissipative control strategies. The redesigned structure is fabricated, assembled in the laboratory, and experimentally compared with the original test structure. Design guides are proposed and used in the integrated design process to ensure that the resulting structure can be fabricated. Experimental results indicate that the integrated design requires greater than 60 percent less average control power (by thruster actuators) than the conventional control-optimized design while maintaining the required line-of-sight performance, thereby confirming the analytical findings about the superiority of the integrated design methodology. Amenability of the integrated design structure to other control strategies is considered and evaluated analytically and experimentally. This work also demonstrates the capabilities of the Langley-developed design tool CSI DESIGN which provides a unified environment for structural and control design.

Maghami, Peiman G.↗

NASA NTRS1978

Large space structures assembly simulation

Simulation requirements for the evaluation of Large Space Structure assembly techniques have been developed by analysis of a typical large space structure through its entire life cycle. Applications of neutral buoyancy, air bearing simulators, computer driven rendezvous and docking simulators, and other simulation modes were studied. Several demonstrations of assembly techniques in neutral buoyancy have been conducted at MSFC using large scale hardware. Experience from those demonstrations and subsequent simulations can be used to select viable approaches for orbital application in operational vehicles. Demonstration results are presented which illustrate techniques and hardware designs that can significantly simplify construction of early large space structures.

Hall, S. B.↗

NASA NTRS2020

Modeling and Control of Robot-Structure Coupling During In-Space Structure Assembly

This paper considers the problem of robot-structure coupling dynamics during in-space robotic assembly of large flexible structures. A two-legged walking robot is used as a construction agent, whose primary goal is to stably walking on the flexible structure while carrying a substructure component to a designated location. The reaction forces inserted by the structure to the walking robot are treated as bounded disturbance inputs, and a trajectory tracking robotic controller is proposed that combines the standard full state feedback motion controller and an adaptive controller to account for the disturbance inputs. In this study, a reduced-order Euler-Bernoulli beam structure model is adapted, and a finite number of co-located sensors and actuators are distributed along the span of the beam structure. The robot-structure coupling forces are treated as a bounded external forcing function to the structure, and hence an output covariance constraint problem can be formulated, in terms of linear matrix inequality, for optimal structure control by utilizing the direct output feedback controllers. The numerical simulations show the effectiveness of the proposed robot-structure modeling and control methodology.

Swei, Sean↗

NASA NTRSDate not supplied

FY22 Precision Assembled Space Structure) PASS Annual Review Presentation

Space Technology Mission Directorate, Game Changing Development Program: Precision Assembled Space Structure (PASS) annual review slides. PASS is an autonomous robotic assembly project with an emphasis on high-precision, high-performance large assembled structures.

Autonomous assembly↗

NASA NTRS1982

Materials technology for large space structures

Several of the key material technology needs that were identified for large space structures are outlined. They include lightweight structural materials, materials durability in the space environment, and some special aspects of materials fabrication technology. Examples of current materials research directed toward large space structures are described. Additional research needs and opportunities are noted. A short bibliography is included of selected references that describe large space structural concepts and related technology needs in detail.

Blankenship, C. P.↗

NASA NTRS1987

Optimal control of large space structures via generalized inverse matrix

Independent Modal Space Control (IMSC) is a control scheme that decouples the space structure into n independent second-order subsystems according to n controlled modes and controls each mode independently. It is well-known that the IMSC eliminates control and observation spillover caused when the conventional coupled modal control scheme is employed. The independent control of each mode requires that the number of actuators be equal to the number of modelled modes, which is very high for a faithful modeling of large space structures. A control scheme is proposed that allows one to use a reduced number of actuators to control all modeled modes suboptimally. In particular, the method of generalized inverse matrices is employed to implement the actuators such that the eigenvalues of the closed-loop system are as closed as possible to those specified by the optimal IMSC. Computer simulation of the proposed control scheme on a simply supported beam is given.

Nguyen, Charles C.↗

NASA NTRS1985

Proceedings of the Workshop on Identification and Control of Flexible Space Structures, volume 1

Identification and control of flexible space structures were studied. Exploration of the most advanced modeling estimation, identification and control methodologies to flexible space structures was discussed. The following general areas were discussed: space platforms, antennas, and flight experiments; control/structure interactions - modeling, integrated design and optimization, control and stabilization, and shape control; control technology; control of space stations; large antenna control, dynamics and control experiments, and control/structure interaction experiments.

Rodriguez, G.↗

NASA NTRS1990

Clevis joint for deployable space structures

This invention relates generally to pin clevis joints, and more particularly, to zero play pin clevis joints for connecting structural members of a deployable space structure. A joint includes a pin, a tang, and a shackle. The pin is tapered at the same angle as the bores extending through the projections of the shackle and the tang. A spring washer biases the tang onto the tapered sidewall of the pin. The invention solves the free play problem associated with deployable space structures by using a tapered pin which is held in tapered holes by the spring washers.

Rhodes, Marvin D.↗

NASA NTRS1990

Active rejection of persistent disturbances in flexible space structures

A dynamic compensator for active rejection of persistent disturbances in flexible space structures is designed on the principle of the H(infinity)-optimization of the sensitivity transfer function matrix. A general state space solution is formulated to the multiinput multioutput H(infinity)-optimal control problem, allowing the use of the H(infinity)-optimal synthesis algorithm for the state-space models of space structures that result from model order reduction. Disturbances encountered in flexible space structures, such as shuttle docking, are investigated using the high-mode and the reduced-order models of a cantilevered two-bay truss, demonstrating the applicability of the H(infinity)-optimal approach.

Hwang, Cheng-Neng↗

NASA NTRS1984

Static shape determination and control for large space structures. I - The flexible beam. II - A large space antenna

A method for determining and controlling the shape of large, continuous space structures by means of discrete or pointwise observations and control devices is presented. The general linear boundary value problem satisfied by a one-dimensional shape function is defined, and the existence of solutions is studied. The static shape control problems for one-dimensional systems with and without rigid body modes and the static shape estimation problem are presented and solved. Eigenfunction expansions are presented which provide approximations to the algorithm terms when the associated Green's function is not known. An integral operator approach is applied to the multidimensional static problem, and the results are illustrated with a finite element model of the disk of a large space antenna which assumes no rigid body modes. It is shown that the shape control algorithm must be modified for systems with rigid body modes.

Weeks, C. J.↗

NASA NTRS1992

Free-decay time-domain modal identification for large space structures

Concept definition studies for the Modal Identification Experiment (MIE), a proposed space flight experiment for the Space Station Freedom (SSF), have demonstrated advantages and compatibility of free-decay time-domain modal identification techniques with the on-orbit operational constraints of large space structures. Since practical experience with modal identification using actual free-decay responses of large space structures is very limited, several numerical and test data reduction studies were conducted. Major issues and solutions were addressed, including closely-spaced modes, wide frequency range of interest, data acquisition errors, sampling delay, excitation limitations, nonlinearities, and unknown disturbances during free-decay data acquisition. The data processing strategies developed in these studies were applied to numerical simulations of the MIE, test data from a deployable truss, and launch vehicle flight data. Results of these studies indicate free-decay time-domain modal identification methods can provide accurate modal parameters necessary to characterize the structural dynamics of large space structures.

Kim, Hyoung M.↗

NASA NTRS1981

Structural sizing considerations for large space structures

A number of missions for the space shuttle were proposed which involve placing large truss platforms on-orbit. These platforms range in size from tens of meters in span for reflector application to several thousand meters for solar power collector application. These proposed sizes and the operational requirements considered are unconventional in comparison to Earthbound structures and little information exists concerning efficient proportions of the structural elements forming the framework of the platforms. Such proportions are of major concern because they have a strong influence on the packaging efficiency and, thus, the transportation effectiveness of the shuttle. The present study is undertaken to: (1) identify efficient ranges of application of deployable and erectable platforms configured for shuttle transport to orbit, and (2) determine sensitivity to key parameters of minimum mass deployable and erectable platform designs.

Heard, W. L., Jr.↗

NASA NTRS1991

NASA/MSFC Large Space Structures Ground Test Facility

This paper describes the NASA/MSFC Large Space Structures Ground Test Facility (LSS GTF) which has been developed for the purpose of implementing, testing, and evaluating LSS control and system identification techniques on representative large space structures. The facility presently consists of two laboratories: the Single Structure Control (SSC) Laboratory, which has been operational since 1984, and the Controls and Structures Experiment in Space (CASES) GTF which is presently under development. Test results from several experiments in the SSC laboratory are presented. The results of component testing and boom modal tests are presented for the CASES facility.

Jones, Victoria L.↗

NASA NTRS1990

Numerical simulation of actively controlled space structures

The numerical simulation of large, actively controlled space structures is a problem that has received considerable attention. A new computational method is presented in this paper, which simulates the vibration suppression of a large space structure by a linear compensator. The structure is assumed to be modeled by a large linear finite element model. Nested circularly linked lists and the trapezoidal rule are key aspects of this algorithm. There is an emphasis on generality, while establishing an equivalence between numerical stability and system stability.

Quan, Ralph↗

NASA NTRS1988

Emulating a flexible space structure: Modeling

Control Dynamics, in conjunction with Marshall Space Flight Center, has participated in the modeling and testing of Flexible Space Structures. Through the series of configurations tested and the many techniques used for collecting, analyzing, and modeling the data, many valuable insights have been gained and important lessons learned. This paper discusses the background of the Large Space Structure program, Control Dynamics' involvement in testing and modeling of the configurations (especially the Active Control Technique Evaluation for Spacecraft (ACES) configuration), the results from these two processes, and insights gained from this work.

Waites, H. B.↗