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Experiments in cooperative-arm object manipulation with a two-armed free-flying robotDeveloping computed-torque controllers for complex manipulator systems using current techniques and tools is difficult because they address the issues pertinent to simulation, as opposed to control. A new formulation of computed-torque (CT) control that leads to an automated computer-torque robot controller program is presented. This automated tool is used for simulations and experimental demonstrations of endpoint and object control from a free-flying robot. A new computed-torque formulation states the multibody control problem in an elegant, homogeneous, and practical form. A recursive dynamics algorithm is presented that numerically evaluates kinematics and dynamics terms for multibody systems given a topological description. Manipulators may be free-flying, and may have closed-chain constraints. With the exception of object squeeze-force control, the algorithm does not deal with actuator redundancy. The algorithm is used to implement an automated 2D computed-torque dynamics and control package that allows joint, endpoint, orientation, momentum, and object squeeze-force control. This package obviates the need for hand-derivation of kinematics and dynamics, and is used for both simulation and experimental control. Endpoint control experiments are performed on a laboratory robot that has two arms to manipulate payloads, and uses an air bearing to achieve very-low drag characteristics. Simulations and experimental data for endpoint and object controllers are presented for the experimental robot - a complex dynamic system. There is a certain rather wide set of conditions under which CT endpoint controllers can neglect robot base accelerations (but not motions) and achieve comparable performance including base accelerations in the model. The regime over which this simplification holds is explored by simulation and experiment.
Document ID
19910012216
Acquisition Source
Legacy CDMS
Document Type
Thesis/Dissertation
Authors
Koningstein, Ross (Stanford Univ. CA, United States)
Date Acquired
September 6, 2013
Publication Date
October 1, 1990
Subject Category
Mechanical Engineering
Report/Patent Number
NASA-CR-188028
SUDAAR-597
NAS 1.26:188028
Accession Number
91N21529
Funding Number(s)
CONTRACT_GRANT: NCC2-333
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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