Transcript Design of Low-Power Silicon Articulate Microrobots

Design of Low-Power Silicon
Articulated Microrobots
Richard Yeh & Kristofer S. J. Pister
Presented by:
Shrenik Diwanji
Abstract

To design and build a class of autonomous,
low power silicon articulated micro-robots
fabricated on a 1 cm2 silicon die and
mounted with actuators, a controller and a
solar array.
Designing
Primarily based on micro-machining
 Pros
Feature
sizes in sub micron
Mass production
 Cons
Designing from scratch
Basic model of the micro-robot.
Actuator Design
 Main
backbone of the robot design
 Should have high W/kg3 ratio
 Different types of actuators: Piezoelectric
 Thermal
and shape-memory alloy
 Electromagnetic
 Electrostatic
Piezoelectric actuators
 Pros
 Produce
large force
 Require low power
 Cons
 Require
high voltage ~ 100v.
 difficult to integrate with CMOS electronics
Thermal and Shape-memory alloy
actuators
 Pros
 Robust
 Easy
to operate
 Cons
 High
current dissipation ( 10s of mA)
Electromagnetic actuators

Pros


High Energy Density
Cons

Needs external magnet and / or high
currents to generate high magnetic fields
Electrostatic actuators
 Pros
 Low
power dissipation.
 Can be designed to dissipate no power
while exerting a force.
 High power density at micro scale.
 Easy to fabricate.
Electrostatic actuator design

Gap Contraction Actuator
2
_
1Et
l
v
Fe =
2 d2
Scaling Effects
Actuator force
Dissipative force
Gravitational force
Squeeze-film damping
Frequency
Resistance of spring support
Power density
Inch Worm Motors.
Design of Inch Worm Motors
Inch Worm Cycle
Prototype design and working
Power requirements
 Main
areas of power dissipation
 CMOS
controller
 Actuators
 Power
dissipation in actuators
 Weight
 Adhesion
force
- 0.5mN
- 100µN
C = Total capacitance
F = frequency
Designing Articulated Rigid Links

Shape of the links
 Flat

links
Cons

Less strength due to 2 thin poly crystalline layers
 HTB

Pros

Good weight bearing capacity
Designing Articulated Rigid Links
 Mounting
of the solar array and the chip
 Mechanical
Coupling of the legs
Power Source

Solar array is used
 η = 10 % ( max 26%)
 Power density = 10mW/cm2 (100 mw/cm2, η = 26%)
Controller
 Open
loop control (as no sensors)
 CMOS controller
 Simple
finite state machine
 Clock generator
 Charge pump
Logic behind walking of the Robot
Gait speed
speed = Δx/T
 In one leg cycle
 Gait
 Δx = 100μm
 T = 15 ms.
 With
GCA to leg displacement factor of 1:10
 GCA gap – stop size of 2μm.
 Operating frequency of 1kHz.

Gait Speed = 100/15 = 7mm/s
Robot assembly
 Difficulty
 The
size of the robot
 The strength needed for perfect
mechanical coupling
 Solution
 Flip

chip bonding
Allows the micro machined devices to be
transferred from substrate to another.
Conclusion
 Key
design issues
 Actuation
power density
 Actuators used
 Key
tools
 Micro
machining