Comparing%20the%20Locomotion%20Dynamics%20of%20a%20Cockroach%20and%20a%20Shape%20Deposition%20Manufactured%20Biomimetic%20Robot

1
Comparing the Locomotion Dynamics of a Cockroach
and a Shape Deposition Manufactured Biomimetic
Robot
Sean A. Bailey, Jorge G. Cham, Mark R.
Cutkosky Biomimetic Robotics Lab Stanford
University
Robert J. Full PolyPedal Laboratory University of
California at Berkeley
December 12, 2000
2
Overview

• Introduction
• Shape Deposition Manufacturing
• Robot Design
• Locomotion Dynamics
• Conclusions

3
Introduction

• Motivation
• Small
• Fast
• Robust
• Integrated approach
• Biomimetic structures
• Biologically-inspired control

De-mining in an unstructured environment
4
Shape Deposition Manufacturing (SDM)
Manufacturing
Prototype Limb with Embedded Pneumatic Actuator,
Sensor, Leaf Spring and Valves
5
Shape Deposition Manufacturing (SDM)

• Arbitrary geometries
• Embedded components
• No fasteners
• Multi-materials
• Tailored compliance

Graded, multi-material 5-bar
6
Biological Example

• Death-head cockroach Blaberus discoidalis
• Fast
• Speeds of up to 10 body/s
• Rough terrain
• Can easily traverse fractal terrain of obstacles
  3X hip height

Blaberus discoidalis running over fractal terrain
7
Biological Inspiration

• Control heirarchy
• Passive component
• Active component

Neural System (CPG)
Feedforward Motor Pattern
Sensory Feedback (Reflexes)
Mechanical System (muscles, limbs)
Mechanical Feedback (Preflexes)
Environment
Passive Dynamic Self-Stabilization
Locomotion
Full and Koditschek, 1999
8
Robot Design
Cockroach Geometry
Functional Biomimesis
Robot Implementation

• Passive Compliant Hip Joint
• Effective Thrusting Force

• Damped, Compliant Hip Flexure
• Embedded Air Piston

• Rotary Joint
• Prismatic Joint

Cham et al., 2000, Clark et al., 2001
9
Sprawlita
Actuators and wiring embedded inside structure

• Mass - .27 kg
• Dimensions - 16x10x9 cm
• Leg length - 4.5 cm
• Max. Speed - 55 cm/s 3 body/sec
• Hip height obstacle traversal

Legs with Compliant Flexures
2.5 cm
10
Movie

• Superficially insect-like
• Stable running
• Obstacle traversal

11
Whole Body Dynamics

• Force plate
• High speed video

Force Plate Data
High-speed Footage with Markers
12
Animal Running - the SLIP model
SIX-
Legged
Legged
EIGHT-
Cockroach
Crab
B
o
d
y
V
e
r
t
i
c
a
l
TWO-
Legged
W
e
i
g
h
t
Legged
FOUR-
F
o
r
c
e
Fore-aft
F
o
r
c
e
T
i
m
e
Spring-Loaded Inverted Pendulum SLIP
Blickhan 1989
Human
Dog
Cavagna et al., 1975
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Whole Body Ground Reaction Forces
Spring-Loaded Inverted Pendulum (SLIP)
Blaberus discoidalis
Sprawlita
6
0.025
4
Vertical Force
0.02
2
0.015
.004
2
0
Fore-aft Force
0
-.004
-2
0
50
100
20
40
60
80
Time
Time (ms)
Time (ms)
Dragging
Accelerate
Accelerate
Decelerate
Decelerate
Decelerate
Accelerate
14
Individual leg forces

• Sprawlita drags middle and rear foot
• Individual legs have functions dissimilar from
  cockroach legs
• More questions
• Relative contact time

Front Leg
Middle Leg
Hind Leg
10
12
10
0
0
0
mN
ms
-6
-6
-6
0
140
0
60
140
0
140
4
4
4
0
0
0
N
ms
-2
-2
-2
0
20
50
0
50
0
50
filtered vertical force
filtered horizontal force
Dragging
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Summary and Conclusions

• Sprawlita
• Physically robust
• Operationally robust
• Open loop
• Comparing locomotion dynamics suggests design
  improvements
• Foot drag - longer stroke
• If more SLIP-like...
• faster?
• more efficient?
• more robust?

16
Future Work

• Sprawley Davidson
• Leg extensions
• The Sprawlettes
• High level, not real-time sensor-based control

17
Acknowledgements

• Stanford
• Center for Design Research
• Dexterous Manipulation Lab
• Rapid Prototyping Lab
• Berkeley
• PolyPedal Lab
• Sponsors
• Office of Naval Research
• National Science Foundation