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STABILITY OF CONTROL FORCES IN REDUNDANT MULTIBODY SYSTEMS

1996-01-03
IDER, SK
In this paper inverse dynamics of redundant multibody systems using a minimum number of control forces is formulated. It is shown that the control forces and the task accelerations may become noncausal at certain configurations, yielding the dynamical equation set of the system to be singular. For a given set of tasks, each different set of actuators leads to a different system motion and also to different singular configurations. To avoid the singularities in the numerical solution, the dynamical equations are modified in the neighborhoods of the singular configurations by utilizing higher order derivative information. The modification is made easier by transforming the equations of motion to the null space of the control force direction matrix. The conditions for the existence of solution are also discussed. A redundant planar manipulator is analyzed to illustrate the methods proposed.