Fin Failure Compensation for an Unmanned Underwater Vehicle
A. S.-F. Cheng and N.E. Leonard
Proceedings of the 11th Internation Symposium on
Unmanned Untethered Submersible Technology,
We study fin failures on a torpedo-shaped unmanned underwater
vehicle (UUV) and design control laws to compensate for a fin
that gets stuck at an arbitrary deflection angle.
Our control strategy combines sliding mode control with
modified fin mixing and a method for handling fin deflection
saturation. The saturation-compensating control design follows
recent work of Teel and Kapoor
and has the advantage that it is only
active when there is saturation. This allows the nominal
controller to be designed independently for desired performance
under non-saturation conditions.
Our complete controller has been tested on the simulator for
the 21UUV, a full-scale, 21-inch diameter, torpedo-shaped UUV.
We describe the results of these tests which
demonstrate good tolerance to a fin failure.
As our objective is the design of failure compensation,
we assume in our work that we have available an identification
package that provides fin failure information.
Our simulator test results
suggest, however, that only very little information about the
failure is required for effective compensation.
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