A study of intense magnetic fields for high energy forming and structural assembly Interim report
Determination of maximum force on static sheet of aluminum subjected to magnetic field of hammer coil
MAGNETIC FIELD↗
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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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Hypersonic research engine project. Phase 2: Structures assembly model test procedure
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Platte, W.↗
Panel installation development in Automated Structures Assembly Lab
The design requirements for panel installation process are listed and photographs are presented of the following: panel latches to truss via adaptors; panel end effector; arm retrieving panel from canister; arm installing panel; and facility view with panel installed.
Cuong Quach↗
Gripper for truss structure assembly
The CIRSSE two-finger gripper is designed to be used with a 6-axis wrist-mounted force-torque sensor as part of an experimental testbed for cooperative robotic manipulation. The gripper system consists of a dedicated controller and a pneumatic powered gripper that is servoed in position or grasping force. The gripper also has a between fingertip light beam sensor. The major features of this new design are: high grasping force to weight ratio (25::1) and compactness (14 cm base-fingertip, 0.8 kilograms); low cost dedicated slave controller; and simple host-controller communications protocol to minimize command interpretation delay. Shared software functions between the host and the controller processor permit the host to select servo mode, servo gain-parameter values, and calibration offsets. Hidden primitive self-test, calibration and servo confidence functions are included.
Kelley, Robert B.↗
Telerobotics test bed for space structure assembly
A cooperative research on super long distance space telerobotics is now in progress both in Japan and USA. In this program. several key features will be tested, which can be applicable to the control of space robots as well as to terrestrial robots. Local (control) and remote (work) sites will be shared between Electrotechnical Lab (ETL) of MITI in Japan and Jet Propulsion Lab (JPL) in USA. The details of a test bed for this international program are discussed in this report.
Kitami, M.↗
Structure Assembly by a Heterogeneous Team of Robots Using State Estimation, Generalized Joints, and Mobile Parallel Manipulators
Autonomous robotic assembly by mobile field robots has seen significant advances in recent decades, yet practicality remains elusive. Identified challenges include better use of state estimation to and reasoning with uncertainty, spreading out tasks to specialized robots, and implementing representative joining methods. This paper proposes replacing 1) self-correcting mechanical linkages with generalized joints for improved applicability, 2) assembly serial manipulators with parallel manipulators for higher precision and stability, and 3) all-in-one robots with a heterogeneous team of specialized robots for agent simplicity. This paper then describes a general assembly algorithm utilizing state estimation. Finally, these concepts are tested in the context of solar array assembly, requiring a team of robots to assemble, bond, and deploy a set of solar panel mockups to a backbone truss to an accuracy not built into the parts. This paper presents the results of these tests.
Komendera, Erik E.↗
Robotically Assembled Aerospace Structures: Digital Material Assembly using a Gantry-Type Assembler
This paper evaluates the development of automated assembly techniques for discrete lattice structures using a multi-axis gantry type CNC machine. These lattices are made of discrete components called digital materials. We present the development of a specialized end effector that works in conjunction with the CNC machine to assemble these lattices. With this configuration we are able to place voxels at a rate of 1.5 per minute. The scalability of digital material structures due to the incremental modular assembly is one of its key traits and an important metric of interest. We investigate the build times of a 5x5 beam structure on the scale of 1 meter (325 parts), 10 meters (3,250 parts), and 30 meters (9,750 parts). Utilizing the current configuration with a single end effector, performing serial assembly with a globally fixed feed station at the edge of the build volume, the build time increases according to a scaling law of n4, where n is the build scale. Build times can be reduced significantly by integrating feed systems into the gantry itself, resulting in a scaling law of n3. A completely serial assembly process will encounter time limitations as build scale increases. Automated assembly for digital materials can assemble high performance structures from discrete parts, and techniques such as built in feed systems, parallelization, and optimization of the fastening process will yield much higher throughput.
Mechanical Structure↗
Robotically Assembled Aerospace Structures: Digital Material Assembly using a Gantry-Type Assembler
This paper evaluates the development of automated assembly techniques for discrete lattice structures using a multi-axis gantry type CNC machine. These lattices are made of discrete components called "digital materials." We present the development of a specialized end effector that works in conjunction with the CNC machine to assemble these lattices. With this configuration we are able to place voxels at a rate of 1.5 per minute. The scalability of digital material structures due to the incremental modular assembly is one of its key traits and an important metric of interest. We investigate the build times of a 5x5 beam structure on the scale of 1 meter (325 parts), 10 meters (3,250 parts), and 30 meters (9,750 parts). Utilizing the current configuration with a single end effector, performing serial assembly with a globally fixed feed station at the edge of the build volume, the build time increases according to a scaling law of n4, where n is the build scale. Build times can be reduced significantly by integrating feed systems into the gantry itself, resulting in a scaling law of n3. A completely serial assembly process will encounter time limitations as build scale increases. Automated assembly for digital materials can assemble high performance structures from discrete parts, and techniques such as built in feed systems, parallelization, and optimization of the fastening process will yield much higher throughput.
Manufacturing↗
Robotic Assembly of Truss Structures for Space Systems and Future Research Plans
Many initiatives under study by both the space science and earth science communities require large space systems, i.e. with apertures greater than 15 m or dimensions greater than 20 m. This paper reviews the effort in NASA Langley Research Center's Automated Structural Assembly Laboratory which laid the foundations for robotic construction of these systems. In the Automated Structural Assembly Laboratory reliable autonomous assembly and disassembly of an 8 meter planar structure composed of 102 truss elements covered by 12 panels was demonstrated. The paper reviews the hardware and software design philosophy which led to reliable operation during weeks of near continuous testing. Special attention is given to highlight the features enhancing assembly reliability.
Doggett, William↗
Controls for space structures
Assembly and operation of large space structures (LSS) in orbit will require robot-assisted docking and berthing of partially-assembled structures. These operations require new solutions to the problems of controls. This is true because of large transient and persistent disturbances, controller-structure interaction with unmodeled modes, poorly known structure parameters, slow actuator/sensor dynamical behavior, and excitation of nonlinear structure vibrations during control and assembly. For on-orbit assembly, controllers must start with finite element models of LSS and adapt on line to the best operating points, without compromising stability. This is not easy to do, since there are often unmodeled dynamic interactions between the controller and the structure. The indirect adaptive controllers are based on parameter estimation. Due to the large number of modes in LSS, this approach leads to very high-order control schemes with consequent poor stability and performance. In contrast, direct model reference adaptive controllers operate to force the LSS to track the desirable behavior of a chosen model. These schemes produce simple control algorithms which are easy to implement on line. One problem with their use for LSS has been that the model must be the same dimension as the LSS - i.e., quite large. A control theory based on the command generator tracker (CGT) ideas of Sobel, Mabins, Kaufman and Wen, Balas to obtain very low-order models based on adaptive algorithms was developed. Closed-loop stability for both finite element models and distributed parameter models of LSS was proved. In addition, successful numerical simulations on several LSS databases were obtained. An adaptive controller based on our theory was also implemented on a flexible robotic manipulator at Martin Marietta Astronautics. Computation schemes for controller-structure interaction with unmodeled modes, the residual mode filters or RMF, were developed. The RMF theory was modified to compensate slow actuator/sensor dynamics. These new ideas are being applied to LSS simulations to demonstrate the ease with which one can incorporate slow actuator/sensor effects into our design. It was also shown that residual mode filter compensation can be modified for small nonlinearities to produce exponentially stable closed-loop control. A theory for disturbance accommodating controllers based on reduced order models of structures was developed, and stability results for these controllers in closed-loop with large-scale finite element models of structures were obtained.
Balas, Mark↗
Large platform assembler non-structural system requirements
The impact on the design and operation of an automated structure assembler of requiring the assembler to also install the platform electrical and/or fluid utility circuits was examined. Possible utility requirements were defined and examined in conjunction with the automated assembler. Preliminary concepts are presented which permit the electrical and fluid circuits to be installed with the structural elements.
Vernon, R. M.↗
Development of a machine vision guidance system for automated assembly of space structures
The topics are presented in viewgraph form and include: automated structural assembly robot vision; machine vision requirements; vision targets and hardware; reflective efficiency; target identification; pose estimation algorithms; triangle constraints; truss node with joint receptacle targets; end-effector mounted camera and light assembly; vision system results from optical bench tests; and future work.
Eric G Cooper↗
Robotic assembly of large space structures
The Automated Structures Assembly Laboratory (ASAL) has been developed at LaRC for the following purposes: identifying the problems associated with assembling large space structures using robotic manipulators; investigating systems and techniques applicable to such assembly tasks; and developing methodology for an in-space construction facility. The ASAL facility and its robotic manipulator system is described, and a discussion of the initial series of assembly operations are included. The status of the system software development is summarized, and an outline for follow-on testing and expanded capability is given.
Will, Ralph W.↗
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↗
Concentric Nested Toroidal Inflatable Structures
Assemblies comprising multiple limited- height toroidal inflatable structures nested in a concentric arrangement have been invented to obtain more design flexibility than can be obtained in single taller, wider toroidal inflatable structures (see figure). Originally intended for use as containers for habitats for humans in outer space or on remote planets, these and related prior inflatable structures could also be useful on Earth as lightweight, compactly stowable, portable special-purpose buildings that could be transported to remote locations and there inflated to full size and shape. In the case of a single inflatable toroidal structure, one important source of lack of design flexibility is the fact that an increase in outer diameter (which is sometimes desired) is necessarily accompanied by an increase in height (which is sometimes undesired). Increases in diameter and height can also cause difficulty in utilization of the resulting larger volume, in that it can become necessary to partition the volume by means of walls and floors, and features (e.g., stairs or ladders) must be added to enable vertical movement between floors. Moreover, ascending and descending between floors in a gravitational environment could pose unacceptable difficulty for the inhabitants under some circumstances. Another source of lack of design flexibility in a single toroidal inflatable structure is that for a given inflation pressure, an increase in the outer diameter of the structure necessarily entails an increase in the maximum stress in the structure. Because it is necessary to keep the maximum stress within the load-bearing capability of the structural materials, consistent with other aspects of the design, this may translate to a limit on the outer diameter. In an assembly comprising concentric nested toroidal structures, an increase in outer diameter does not necessarily entail an increase in height or a maximum stress in excess of the load-bearing capability of the structural materials. The minor diameters of the nested toroid can be chosen to partition interior spaces optimally, without necessitating the addition of walls or floors. Inasmuch as the maximum stress in a nested inflatable toroidal structure is a function of its minor diameter and the minor diameter is typically small enough that the load-bearing capability of the structural materials is not exceeded, there is no longer a limit on the outer diameter of the assembly: instead, the assembly can be expanded, without limit, by simply adding concentric inflatable toroidal structures having suitable minor diameters and successively larger major diameters. The minor diameters need not be equal:
Johnson, Christopher J.↗
General description of nestable column structural and assembly technology
The superior packaging characteristics of nestable column structural elements make this concept attractive for application to missions space shuttle missions requiring large and/or high stiffness, or complex structures. Photographs depict investigations pursued relative to defining structural and assembly technology using these structural elements. The neutral buoyancy facility assembly simulation tests and the large space structure mobile work station are featured.
Bush, H. G.↗
Designing sub-20 nm self-assembled nanocarriers for small molecule delivery: Interplay among structu
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Jung, Benson T.↗
Planning Assembly Of Large Truss Structures In Outer Space
Report dicusses developmental algorithm used in systematic planning of sequences of operations in which large truss structures assembled in outer space. Assembly sequence represented by directed graph called "assembly graph", in which each arc represents joining of two parts or subassemblies. Algorithm generates assembly graph, working backward from state of complete assembly to initial state, in which all parts disassembled. Working backward more efficient than working forward because it avoids intermediate dead ends.
De Mello, Luiz S. Homem↗