Design of an Autonomous Jumping Microrobot Sarah Bergbreiter and Prof. Kris Pister Berkeley Sensor and Actuator Center University of California, Berkeley
Dec 21, 2015
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