11,387 research outputs found
Control of free-flying space robot manipulator systems
New control techniques for self contained, autonomous free flying space robots were developed and tested experimentally. Free flying robots are envisioned as a key element of any successful long term presence in space. These robots must be capable of performing the assembly, maintenance, and inspection, and repair tasks that currently require human extravehicular activity (EVA). A set of research projects were developed and carried out using lab models of satellite robots and a flexible manipulator. The second generation space robot models use air cushion vehicle (ACV) technology to simulate in 2-D the drag free, zero g conditions of space. The current work is divided into 5 major projects: Global Navigation and Control of a Free Floating Robot, Cooperative Manipulation from a Free Flying Robot, Multiple Robot Cooperation, Thrusterless Robotic Locomotion, and Dynamic Payload Manipulation. These projects are examined in detail
Aeroplane design study STOL airliner (A71). Part 2- detail design features
This report is concerned with a description of the detail
design features of the A71 project study. This aircraft is
an airliner designed for operation off single 2000 ft long
runways. The overall description of the design and its
aerodynamic characteristics are contained in Part I of the
report (Ref.1).
The detail design of the structure and systems is
conventional in most respects. The need to provide a long
stroke undercarriage for STOL operations incurred a large
weight penalty and it is concluded that further work is
necessary to establish acceptable requirements for this type
of undercarriage. A separate investigation (Ref.3) has shown
that the aircraft does not meet its stipulated design
objectives due to an inability to cope with engine failure
and gusting cross wind conditions. A study to investigate
the potential of the cross-coupling of adjacent powerplants
to mitigate engine failure control problems suggests that
the weight penalty is not justified (Ref.-)
On-Orbit Assembly of Flexible Space Structures with SWARM
On-orbit assembly is an enabling technology for many space applications. However, current methods of human assisted assembly are high in cost and risk to the crew, motivating a desire to automate the on-orbit assembly process using robotic technology. Construction of large space structures will likely involve the manipulation of flexible elements such as trusses or solar panels, and automation for assembly of flexible structures has significant challenges, particularly in control systems. This paper presents results of ground-based experiments on the assembly of a flexible space structures using the hardware developed under the Self-Assembling Wireless Autonomous Reconfigurable Modules (SWARM) program. Results are shown for a series of incremental tests that demonstrate control of a flexible structure, docking, and reconfiguration after docking. These results demonstrate the feasibility of the assembly of flexible structures using this methodology.United States. National Aeronautics and Space Administration. Small Business Innovation Program (Contract NNM07AA22C
Simulation of hyperelastic materials in real-time using Deep Learning
The finite element method (FEM) is among the most commonly used numerical
methods for solving engineering problems. Due to its computational cost,
various ideas have been introduced to reduce computation times, such as domain
decomposition, parallel computing, adaptive meshing, and model order reduction.
In this paper we present U-Mesh: a data-driven method based on a U-Net
architecture that approximates the non-linear relation between a contact force
and the displacement field computed by a FEM algorithm. We show that deep
learning, one of the latest machine learning methods based on artificial neural
networks, can enhance computational mechanics through its ability to encode
highly non-linear models in a compact form. Our method is applied to two
benchmark examples: a cantilever beam and an L-shape subject to moving punctual
loads. A comparison between our method and proper orthogonal decomposition
(POD) is done through the paper. The results show that U-Mesh can perform very
fast simulations on various geometries, mesh resolutions and number of input
forces with very small errors
A simple 5-DOF walking robot for space station application
Robots on the NASA space station have a potential range of applications from assisting astronauts during EVA (extravehicular activity), to replacing astronauts in the performance of simple, dangerous, and tedious tasks; and to performing routine tasks such as inspections of structures and utilities. To provide a vehicle for demonstrating the pertinent technologies, a simple robot is being developed for locomotion and basic manipulation on the proposed space station. In addition to the robot, an experimental testbed was developed, including a 1/3 scale (1.67 meter modules) truss and a gravity compensation system to simulate a zero-gravity environment. The robot comprises two flexible links connected by a rotary joint, with a 2 degree of freedom wrist joints and grippers at each end. The grippers screw into threaded holes in the nodes of the space station truss, and enable it to walk by alternately shifting the base of support from one foot (gripper) to the other. Present efforts are focused on mechanical design, application of sensors, and development of control algorithms for lightweight, flexible structures. Long-range research will emphasize development of human interfaces to permit a range of control modes from teleoperated to semiautonomous, and coordination of robot/astronaut and multiple-robot teams
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