Underwater Robots - Gianluca Antonelli.pdf

120 6. Kinematic Control of UVMSs
[m] [rad]
3
2
1
0.8
x
y
0.6
u
ψ 0.4
v
r
0
0 5 10 15
time [s]
[m/s] [rad/s]
0.2
0
−0.2
0 5 10 15
time [s]
Fig. 6.8. Time history of vehicle position and velocity variables with given endeffector
trajectory and manipulator dexterity
athird case study has been developed. Two simulations have been performed
considering the full-dimensional dynamic model of the NPS AUV under a
sliding mode control law [21] and the following constant and irrotational
current
ν I c =[0 . 1 √ 2 0. 1 √ 2 0 0 0 0] T .
In the first simulation the vehicle stays still and the generalized control
forces are required to only compensate the current effect, since the NPS AUV
is neutrally buoyant and θ = φ =0.Inthe second simulation the vehicle
moves according tothe results ofthe first simulation inthe first case study;
thus, the generalized control forces are used toboth move the vehicle and to
compensate the current effect.
Figure 6.9 reports the time histories of the 2-norm of the control forces
and moments acting on the vehicle as obtained in the two simulations.
[N]
150
100
50
fixed attitude
re-orientation
0
0 20 40 60 80 100
time [s]
[Nm]
1000
800
600
400
200
fixed attitude
re-orientation
0
0 20 40 60 80 100
time [s]
Fig. 6.9. Time history of the 2-norm of the vehicle forces (left) and moments
(right)