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Design of an Autonomous Jumping Microrobot
Sarah Bergbreiter and Prof. Kris PisterBerkeley Sensor and Actuator Center
University of California, Berkeley
Motivation
• Make Silicon Move!
• Mobile Sensor Networks– Monitoring/surveillance– Search and rescue
• Bi-modal transportation– Walking, Flying
Jumping: Locomotion
• Mobility– Obstacles are large
• Efficiency– What time and energy is required to move a microrobot 1
m and what size obstacles can these robots overcome?
50 m
130 mJ
417 min
10 mg
1 cm
5 mJ
1 min
10 mg
**
1.5 mJ
15 sec
11.9 mg
Obstacle Size
Energy
Time
Mass
Hollar (Walking)
Proposed (Jumping)
Ant (Walking)
A. Lipp, H. Wolf, and F.O. Lehmann., “Walking on inclines: energetics of locomotion in the ant Camponotus," Journal of Experimental Biology 208(4) Feb 2005, 707-19.S. Hollar, "A Solar-Powered, Milligram Prototype Robot from a Three-Chip Process," in Mechanical Engineering: University of California, Berkeley, 2003.
Jumping: Challenges
• Kinetic energy for jump derived from work done by motors– High force, large throw
motors
• Short legs require short acceleration times– Use energy storage and
quick release
vlt legacc 2=
Robot Design
• Power for motors and control
• Controller to tell robot what to do
• Spring for energy storage
• Higher force, larger displacement motor
• Landing and resetting for next jump are NOT discussed
Power
Control
1 mm
Motors
Energy Storage
rubber
Power and Control: Design
• Power Design– Small mass and area – Few (or no) additional
components– Simple integration to motors– Supports multiple jumps
• Control Design– Small size– Low power– Simple integration– Programmability– Off-the-shelf
EM6580, 3.5 mg
2 m
m
1.8
mm
Bellew, Hollar (Transducers 2003), 2.3 mg
Energy Storage: Design
• Small area and mass• High efficiency• Store large amounts of energy (10s of J)
– Support large deflections (many mm) – Withstand high forces (many mN)
• Integrate easily with MEMS actuators without complex fabrication
Material E (Pa) Maximum Strain (%)
Tensile Strength (Pa)
Energy Density (mJ/mm3)
Silicon 169x109 0.6 1x109 3
Silicone 750x103 350 2.6x106 4.5
Resilin 2x106 190 4x106 4
Energy Storage: Fabrication
100 m500m
Sylgard® 186 30 m
100 m
• Stored ~ 20 J– Equivalent to 20
cm jump height
• Around 90% efficient
Actuators: Design
• Small area and mass• Low input power and moderate voltage• Reasonable speed • Do large amounts of work (10s of J) to
store energy for jump– Large displacements (5 mm)– High forces (10 mN)
• Simple fabrication
1 mm
l
+-V g
t
k
F
Actuators: Inchworm Motors
• Inchworm actuation accumulates short displacements for long throw
• May be fabricated in single mask SOI process
Actuators: Inchworm Motors
• Inchworm actuation accumulates short displacements for long throw
• May be fabricated in single mask SOI process
Actuators: Inchworm Motors
• Inchworm actuation accumulates short displacements for long throw
• May be fabricated in single mask SOI process
Actuators: Inchworm Motors
• Inchworm actuation accumulates short displacements for long throw
• May be fabricated in single mask SOI process
Actuators: Inchworm Motors
• Inchworm actuation accumulates short displacements for long throw
• May be fabricated in single mask SOI process
Actuators: Inchworm Motors
• Inchworm actuation accumulates short displacements for long throw
• May be fabricated in single mask SOI process
Actuators: Inchworm Motors
• Inchworm actuation accumulates short displacements for long throw
• May be fabricated in single mask SOI process
Actuators: Inchworm Motors
• Inchworm actuation accumulates short displacements for long throw
• May be fabricated in single mask SOI process
Actuators: Inchworm Motors
• Inchworm actuation accumulates short displacements for long throw
• May be fabricated in single mask SOI process
250 m
Actuators: Higher Forces
20
202
1
g
AVF ε=
gi,1 gt,f
+V
gi,0 gt,0
gt,gap
Prototypes: System level demo
• 30 V solar cells driving EM6580 microcontroller and small inchworm motor
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
Prototypes: Motor + Elastomer
• Low force electrostatic inchworm motor with micro fabricated rubber band assembled into shuttle
rubber band
Prototypes: Quick Release
• Electrostatic clamps designed to hold leg in place for quick release– Normally-closed
configuration for portability
• Shot a surface mount capacitor 1.5 cm along a glass slide
• Energy released in less than one video frame (66ms)
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
Conclusions
• Designed an autonomous jumping microrobot– Using rubber for energy storage– Higher force actuators
• Fabricated microrobot parts• Demonstrated system-level functionality
• Put it all together to build an autonomous jumping microrobot!
=
Acknowledgments
DARPA/SDR, NSF/COINS
Berkeley Microlab
Seth Hollar and Anita FlynnLeo Choi, Stratos Christianakis, Deepa Mahajan
Prof. Ron Fearing and Aaron Hoover