Effects of grousers on soil • Heuristics for grouser ...
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Grousers ENAE 788X - Planetary Surface Robotics U N I V E R S I T Y O F MARYLAND Grousers • Effects of grousers on soil • Heuristics for grouser number and size • Tractive force with grousers (LRV example) 1 © 2018 David L. Akin - All rights reserved http://spacecraft.ssl.umd.edu
Transcript of Effects of grousers on soil • Heuristics for grouser ...
Grousers ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Grousers• Effects of grousers on soil • Heuristics for grouser number and size • Tractive force with grousers (LRV example)
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© 2018 David L. Akin - All rights reserved http://spacecraft.ssl.umd.edu
Grousers ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Terramechanics Test Rig (CMU)
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Grousers ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Terramechanics Test Rig (CMU)
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Grousers ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Soil Flow Visualization
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Grousers ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Periodic Soil Shearing by Grousers
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Grousers ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Soil Flow with 16 Grousers
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Grousers ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Soil Flow with 48 Grousers
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Grousers ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Soil Excavation by Grousers
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rg
rw
rg > rw
Grousers ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Wheel Parameters
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h
r
z
v
!
�x
Grousers ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Minimum Grouser Condition
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t
rim contact
=�x
v
tgrouser contact
=
!
tgrouser contact
trim contact
!
v
�x
s = 1� v
!r=) v = !r(1� s)
1
r(1� s)�x
h
r
z
v
!
�x
Grousers ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Grouser-Soil Contact Geometry
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Grousers ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Geometric Derivation of Grouser Spacing
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AC =p
(r + h)2 � (r � z)2 AB =p
r2 � (r � z)2
BC = AC �AB = �x
1
(1� s)
2
4s✓
1 +h
r
◆2
�⇣1� z
r
⌘2�r
1�⇣1� z
r
⌘2
3
5
1
r(1� s)
q(1 + h)2 � (1� z)2 �
q1� (1� z)2
�
1
(1� s)
qh2 + 2h+ 2z � z2 �
p2z � z2
�
Grousers ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Required Grouser Spacing
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0"
10"
20"
30"
40"
50"
60"
70"
0" 2" 4" 6" 8" 10" 12"
Angle&be
tween&grou
sers&(d
eg)&
Grouser&Height&(cm)&
0.0" 0.1" 0.2" 0.3" 0.4" 0.5"Slipra(o
NumberofGrousers
24
12
8
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Grousers ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Number of Grousers in Ground Contact
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r = 40.6 cmz = 1.812 cm
Number of grousers = N
Angle between grousers ⌘ =
2⇡
N
LRV example: choose N = 16
Number of grousers in ground contact ⌘ Ng =
2⇡r
N`
Ng = 1.3 ⇡ 1
Distance between grousers ⌘ `g = r =
2⇡r
N
Grousers ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Tractive Force H with Grousers
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0"
50"
100"
150"
200"
250"
300"
350"
400"
0" 2" 4" 6" 8" 10" 12"
Trac%v
e(Force(H((N)(
Grouser(Height((cm)(
0" 0.1" 0.2" 0.4"Slipra(o
Grousers ENAE 788X - Planetary Surface Robotics
U N I V E R S I T Y O FMARYLAND
Grouser Design Reference
Krzysztof Skonieczny, Scott J. Moreland, and David S. Wettergreen, “A Grouser Spacing Equation for Determining Appropriate Geometry of Planetary Rover Wheels” 2012 IEEE/RSJ International Conference on Intelligent Robots and Systems, October 7-12, 2012, Vilamoura, Algarve, Portugal
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