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Underwater Robots - Gianluca Antonelli.pdf

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142 7. Dynamic Control of UVMSs<br />

In [105, 106] some dynamic considerations are given to underline the existence<br />

ofadynamic coupling between vehicle and manipulator. From this<br />

analysis, based onaspecific structure ofanUVMS, aSliding Mode approach<br />

with afeedforward compensation term is presented. Numerical simulation<br />

results show that the knowledge ofthe dynamics allows improvement ofthe<br />

tracking performance.<br />

In [86, 87], during the manipulation motion, the vehicle is assumed tobe<br />

inactive and modeled as apassive joint. Arobust controller, with adisturbance<br />

observer-based action is used and its effectiveness verified ina1-DOF<br />

vehicle carrying a3-DOF manipulator.<br />

Reference [186] presents asliding mode controller that benefits from the<br />

compensation of a multilayer neural network. Simulation with a 2-DOF,<br />

ground-fixed, underwater manipulator isprovided.<br />

In [131, 245] the possibility to mount a force/torque sensor at the<br />

base of the manipulator isconsidered inorder to compensate for the vehicle/manipulator<br />

dynamic interaction. In case of absence of the sensor, [245]<br />

also proposes adisturbance observer. The possibility touse information coming<br />

from another sensor is interesting; however, the practical implementation<br />

of such algorithms is not trivial.<br />

Reference [169] presents an iterative learning control experimentally validated<br />

ona3-DOF manipulator with fixed base. This is first moved inair<br />

and then in water in order to learn the hydrodynamic dynamic contribution<br />

and then use it in afeedforward compensation.<br />

Reference [174], after having reported some interesting dynamic considerations<br />

about the interaction between the vehicle and the manipulator, propose<br />

atwo-time scale control. The vehicle, characterized bylow bandwidth<br />

actuators that can not compensate for the high manipulator bandwidth, is<br />

controlled by asimple P-type action, while the manipulator iscontrolled by<br />

afeedback linearizing controller.<br />

In [162] the model of aplanar motion ofthe AUV Twin-Burger equipped<br />

with a2-link manipulator isdeveloped. AResolved Acceleration Control is<br />

then applied and simulated on the 5-DOFs.<br />

Reference [281] proposes an adaptiveaction mainly based on the transpose<br />

of the Jacobian. The approach is validated on simulations involving a2-DOF<br />

model of ODIN carrying a2-DOF planar manipulator.<br />

Aproblem slightly different isapproached in [200], where the 4-DOF<br />

manipulator Sherpa ,mounted under the ROV Victor 6000 developed at the<br />

Ifremer, is considered. This manipulator has been originally deigned to be<br />

controlled in open-loop by aremote operator via amaster/slave configuration<br />

using ajoystick: it is, thus, not-provided with proprioceptive sensors. The<br />

Authors propose closed-loop system based on an eye-to-hand visual servoing<br />

approach to control its displacement.

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