Cover title

"NPS-ME-91-03."

"September 1991."

AD A242 557

Includes bibliographical references (p. 12-13)

Underactuated mechanisms provide low cost automation and can overcome actuator failures. These mechanisms are more suitable for space applications mainly because of their lower weight and lower power consumption. Typical examples of useful underactuated mechanisms in space would be large space structures and robot manipulators. Such mechanisms are however difficult to control because of the fewer number of actuators in the system. In this paper we formulate the dynamics of an underactuated mechanism using Hamilton's canonical equations. Next, we develop a theorem that provides us with some necessary and some sufficient conditions for the asymptotic stability of autonomous systems. This theorem is more powerful than LaSalle's theorem when higher order derivatives of the Liapunov function can be easily computed. Finally, we use a Liapunov function approach to develop a control strategy that will stabilize an underactuated mechanism in space to an equilibrium manifold. The effectiveness of such control is verified using our asymptotic stability theorem

aq/aq cc:9116 03/26/97

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