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Underwater Robots - Gianluca Antonelli.pdf

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220 8. Interaction Control of UVMSs<br />

[N]<br />

[m]<br />

300<br />

250<br />

200<br />

150<br />

100<br />

50<br />

0<br />

−50<br />

0 2 4<br />

time [s]<br />

6 8<br />

0.5<br />

0<br />

˜y E<br />

˜x E<br />

f e,z<br />

−0.5<br />

0 2 4<br />

time [s]<br />

6 8<br />

Fig. 8.11. Explicit force control scheme 1. Top: time history of the contact force.<br />

Bottom: time history of the end-effector errors along the motion directions<br />

interpretation. Inthe force control scheme 2, instead, the force error builds<br />

acorrection term acting onthe body-fixed velocity references which fed the<br />

available motion control system of the UVMS.<br />

The two proposed control schemes were tested in numerical simulation<br />

case studies and their performance is analyzed. Overall, the force control<br />

scheme 2seems to be preferable with respect to the force control scheme 1<br />

for two reasons. Firstly, itallows the adoption of adaptive motion control<br />

laws, thus making it possible dynamic compensation actions. Secondly, it<br />

naturally embeds the standard motion control of the UVMS, since it acts at<br />

the reference motion variables level.

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