Underwater Robots - Gianluca Antonelli.pdf

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7.9 Virtual Decomposition Based Control 181
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Fig. 7.19. Output feedback control; third case study. Comparison between
the control laws (7.43),(7.44) and (7.63): vehicle control forces. Left: control
law (7.43),(7.44). Right: control law (7.63)
7.9 Virtual Decomposition Based Control
Divide et Impera.
Anonymous from the middle age.
Usually, adaptive control approaches for UVMSs look atthe system as a
whole, giving rise to high-dimensional problems: differently from the case of
earth-fixed manipulators, in the case of UVMSs itisnot possible to achieve
areduction of the number of dynamic parameters to be adapted, since the
base of the manipulator —i.e., the vehicle— has full mobility. As amatter of
fact, the computational load of such control algorithms grows as much as the
fourth-order power ofthe number of the system’s degrees of freedom. Forthis
reason, practical application of adaptive control to UVMS has been limited,
even in simulation, to vehicles carrying arms with very few joints (i.e., two
or three) and usually performing planar tasks.
In this Section an adaptive control scheme for the tracking problem of
UVMS is discussed, which is based on the approach in [325]. Differently
from previously proposed schemes, the serial-chain structure ofthe UVMS