Passive Dynamic Walking Presentation
Transcript of Passive Dynamic Walking Presentation
Passive Dynamic Bipedal Walking with Knees
The Effect of Parameter Variation
Derek Koop, Dean Ferley and Christine Qiong Wu
Department of Mechanical and Manufacturing Engineering
University of Manitoba
2008 North Central ASABE/CSBE Conference
What is passive dynamic walking ?� Passive walking:
A natural steady gait maintained by gravitational forces.-no actuators
� Static vs Dynamic Walking:� Static vs Dynamic Walking:
A static walking mechanism maintains static equilibrium throughout its motion while a dynamic walking mechanism does not.T. McGeer. (1990). “Passive Dynamic Walking,” [Online], pp. 62-82. Available: Sage Journals Online http://ijr.sagepub.com.proxy1.lib.umanitoba.ca/cgi/reprint/9/2/62 [Sept 17, 2008].
What purpose does it serve ?
� Understanding the natural dynamics behind bipedal locomotion.
� Reduces energy requirements when incorporated into actuated designs
T. McGeer. (1990). “Passive Dynamic Walking,” [Online], pp. 62-82. Available: Sage Journals Online http://ijr.sagepub.com.proxy1.lib.umanitoba.ca/cgi/reprint/9/2/62 [Sept 17, 2008].
Our walker – Dexter Mk II
Dexter Mk II - Terminology
Thigh
- Leg Angle
- Step Angle
- Step Length
Shank
- Step Length
Data Collection
Parameters Varied
� Ramp Angle� Home configuration
24
28
32
36
Ste
p L
ength
(cm
)� Foot Design
20
3.75 4.25 4.75 5.25 5.75 6.25
Ramp Angle (degrees)
F1 F2 F3
Parameters Varied� Limb length
� Thigh and shank are proportional
� Thigh and shank are mismatched
� Mass Ratio� Mass Ratio
� Mass addedA. Greaves and I. Lohrenz, A Study in Passive
Dynamic Walking, B. Sc. thesis, Department of
Mechanical Engineering, University of
Manitoba, Winnipeg, Manitoba, 2008.
Dynamic Parameters
� Key Dynamic Parameters that affect the gait pattern:� Radius of Gyration
� Center of Mass
Radius of Gyration = Mass Moment of Inertia� Radius of Gyration = Mass Moment of InertiaMass
� Center of Mass is measured from the hip downward
25
26
27
28
29
Ste
p A
ng
le (
deg
rees
)
Thigh-Shank Mismatch
Mass Distribution
Proportional Thigh-Shank
27
28
29
Ste
p A
ng
le (
deg
rees
)
Thigh-Shank Mismatch
Mass Distribution
Proportional Thigh-Shank25
26
27
28
29
Ste
p A
ng
le (
deg
rees
)
Thigh-Shank Mismatch
Mass Distribution
Proportional Thigh-Shank
Study Comparison
24
32 34 36 38 40 42
3.3
3.4
3.5
3.6
46 48 50 52
Dim
ensi
on
less
Ste
p P
erio
d
Radius of Gyration / Leg Length (%)
3.3
3.4
3.5
3.6
32 34 36 38 40 42
Dim
ensi
on
less
Ste
p P
erio
d
Center of Mass / Leg Length (%)
24
25
26
46 47 48 49 50 51 52
Ste
p A
ng
le (
deg
rees
)
Radius of Gyration / Leg Length (%)
24
46 48 50 52
Proportional Thigh-Shank Study� Originally seems anomalous
� Individual link properties analyzed
55
60
Rad
ius
of
Gyra
tio
n (
%)
50
Cen
ter
of
Mas
s (%
)
40
45
50
55
1 2 3 4 5 6
Rad
ius
of
Gyra
tio
n (
%)
Trial
2.3 3.1 3.2 3.3 3.4 3.5
20
30
40
1 2 3 4 5 6
Cen
ter
of
Mas
s (%
)
Trial
2.3 3.1 3.2 3.3 3.4 3.5
Double Pendulum Simplification
Summary� That the radius of gyration and center of mass are the key dynamic parameters that effect the gait pattern.
� For non-uniform walkers use a double For non-uniform walkers use a double pendulum simplification.
Questions ?