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  • 1
    Publication Date: 2013-08-31
    Description: There has been a long standing interest in the design of controllers for multilegged vehicles. The approach is to apply distributed control to this problem, rather than using parallel computing of a centralized algorithm. Researchers describe a distributed neural network controller for hexapod locomotion which is based on the neural control of locomotion in insects. The model considers the simplified kinematics with two degrees of freedom per leg, but the model includes the static stability constraint. Through simulation, it is demonstrated that this controller can generate a continuous range of statically stable gaits at different speeds by varying a single control parameter. In addition, the controller is extremely robust, and can continue the function even after several of its elements have been disabled. Researchers are building a small hexapod robot whose locomotion will be controlled by this network. Researchers intend to extend their model to the dynamic control of legs with more than two degrees of freedom by using data on the control of multisegmented insect legs. Another immediate application of this neural control approach is also exhibited in biology: the escape reflex. Advanced robots are being equipped with tactile sensing and machine vision so that the sensory inputs to the robot controller are vast and complex. Neural networks are ideal for a lower level safety reflex controller because of their extremely fast response time. The combination of robotics, computer modeling, and neurobiology has been remarkably fruitful, and is likely to lead to deeper insights into the problems of real time sensorimotor control.
    Keywords: MECHANICAL ENGINEERING
    Type: Jet Propulsion Lab., California Inst. of Tech., Proceedings of the 3rd Annual Conference on Aerospace Computational Control, Volume 2; p 664-673
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  • 2
    Publication Date: 2019-06-28
    Description: This paper is concerned with the derivation of the equations of motion for the Spacecraft Control Laboratory Experiment (SCOLE). For future reference, the equations of motion of a similar structure orbiting the earth are also derived. The structure is assumed to undergo large rigid-body maneuvers and small elastic deformations. A perturbation approach is presented where the quantities defining the rigid-body maneuver are assumed to be relatively large, with the elastic deformations and deviations from the rigid-body maneuver being relatively small. The perturbation equations have the form of linear, non-self-adjoint equations with time-dependent coefficients. An active control technique can then be formulated to permit maneuvering of the spacecraft and simultaneously suppressing the elastic vibration.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
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  • 3
    Publication Date: 2019-06-28
    Description: Structural temperatures were measured on a hypersonic wing test structure during a heating test that simulated a Mach 8 thermal environment. Measured data are compared to design calculations and temperature predictions obtained from a finite-difference thermal analysis.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-TM-85918 , H-1271 , A-85137 , NAS 1.15:85918
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  • 4
    Publication Date: 2019-06-28
    Description: Equations of motion, control strategy, perturbation, rigid-body maneuvers, quasi-modal equations, and vibration control are discussed for flexible spacecraft.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Marshall Space Flight Center Structural Dynamics and Control Interaction of Flexible Structures; p 867-880
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  • 5
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    In:  Other Sources
    Publication Date: 2019-06-28
    Description: This paper is concerned with the simultaneous maneuver and vibration control of the Spacecraft Control Laboratory Experiment (SCOLE). Summaries of the derivation of the equations of motion and of a perturbation method permitting a maneuver strategy independent of the vibration control are presented. Some of the problems encountered in dynamical modeling of a flexible spacecraft in an earth-based laboratory are high-lighted and solved. Numerical results demonstrating rotational maneuvers of the SCOLE model are included.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA PAPER 86-1993
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  • 6
    Publication Date: 2019-06-28
    Description: The derivation of the equations describing the vibration of a flexible spacecraft is presented in the context of a perturbation method permitting a maneuver strategy independent of the vibration control. A straightforward open-loop minimum-time rotational maneuver strategy is developed for the spacecraft regarded as a rigid body. Actuator dynamics are considered in the formulation. A maneuver force distribution is developed which excites the least amount of elastic deformation of the flexible parts of the spacecraft. An efficient technique for simulating structural vibrations during a maneuver is presented. Numerical results demonstrate the maneuver strategy and highlight the vibration caused by rotational maneuvers.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA PAPER 86-0906
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  • 7
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    In:  Other Sources
    Publication Date: 2019-07-12
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 11; 542-553
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  • 8
    Publication Date: 2019-07-13
    Description: This paper is concerned with the development of control strategies and mechanisms for robots operating in the micro-gravity environment of Space Station. These robots must be capable of conducting experiments and manufacturing processes without disturbing the micro-gravity environment through base reactions/motions. Approaches discussed for controlling the robot base reactions/motions include strategies making use of manipulators with redundant degrees of freedon, actuators at the robot base, and a redundant (balancing) arm. Two degree-of-freedom, traction-drive joints are discussed as well as the conceptual design for a traction-driven manipulator.
    Keywords: MAN/SYSTEM TECHNOLOGY AND LIFE SUPPORT
    Type: VPI&SU/AIAA Symposium; Jun 29, 1987 - Jul 01, 1987; Blacksburg, VA; United States
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  • 9
    Publication Date: 2019-07-13
    Description: This paper is concerned with the implementation and assessment of joint motion management strategies for kinematically redundant robotic manipulators operating in the micro-gravity environment of Space Station. These robots must be capable of conducting experiments and manufacturing processes without disturbing the micro-gravity environment through base reactions/motions. The redundant degrees of freedom of the manipulator permit the inverse kinematic problem to be solved simultaneously with the minimization of a cost function. The cost function in this case is the weighted sum of the squares of the base forces and moments and is minimized over discrete time segments. The Generalized Inverse Method and Rayleigh Ritz technique are used to solve the combined optimization/inverse kinematics problem. Numerical examples include various robotic configurations and degrees of manipulator redundancy.
    Keywords: MAN/SYSTEM TECHNOLOGY AND LIFE SUPPORT
    Type: AIAA PAPER 88-4121 , AIAA Guidance, Navigation and Control Conference; Aug 15, 1988 - Aug 17, 1988; Minneapolis, MN; United States
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  • 10
    Publication Date: 2019-07-13
    Description: The dynamic formulation, modeling and motion simulation of multijointed open-chained mechanical systems as applied to space-based robotic systems are presented. Equations of motion are formulated in a unique manner based on a form of Lagrange's equations for quasi-coordinates (Boltzmann-Hamel equations). In order that kinematic joint constraints can be satisfied for the situation where some joints have less than three degrees of freedom, the equations are transformed into forms in terms of relative angular velocities and Euler angles. Rigid multibody examples are presented which show that the method can provide a dynamic model of systems of varying complexity.
    Keywords: MECHANICAL ENGINEERING
    Type: VPI&SU Symposium; May 08, 1989 - May 10, 1989; Blacksburg, VA; United States
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