Building small robot legs with prefabricated components is difficult'''

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Building small robot legs with pre-fabricated
components is difficult...
Boadicea leg
Electric motor/link
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IV. Fabrication and integration experiments
200-230pm (Cutkosky, Kenny, Howe)

• Overview of SDM fabrication process,
  capabilities, challenges
• Autonomous robots experiments with UCB, SRI,
  (others?)
• Cooperative robots experiments with Harvard,
  Johns Hopkins, UCB

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Concept design for a biomimetic Insect-Leg
A prototype design of the same leg employing
three-dimensional plastic exoskeleton
surrounding with embedded actuators, sensor and
cooling system.
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Mechanics and muscle activation patterns (R. Full)
Three-dimensional musculo-skeletal model of the
leg of B. discoidalis constructed by Fulls lab.
Simulations such as these help characterize the
role of individual muscles in locomotion.
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Shape Deposition Manufacturing(SU/CMU)
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SDM allows finished parts to be inserted at any
point in the cycle
Green link and red bearings are added as finished
components
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SDM capabilities

• Slides and web pages of parts that would be
  difficult or impossible to create using
  conventional manufacturing methods
• Topology that would be almost impossible with
  conventional machining tilted frame
  (CMU/Stanford)
• Integrated assembly of polymers with embedded
  electronics and interconnects (CMU Frog Man)
• other example parts from RPL at Stanford

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Frogman (CMU)

• Example of polymer component with embedded
  electronics using shape deposition manufacturing

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MicroStructures and Sensors Lab (MSSL)
Kenny

• Research on Fundamental Properties and
  Applications of MEMS-based MicroMechanical
  Devices.
• Micromechanical Sensors.
• Micromechanical Elements for Scientific and
  Technological Collaboration Partners.
• Devices and Instruments for Studies of
  Fundamental Properties of Micromechanical
  Structures.
• Collaborators IBM, JPL, NRL, SNL, SAIC,
  Medtronic, Raychem, Lucas, Seagate,
  Perkin-Elmer...
• Students from ME, EE, Appl Phys, A/A

Piezoresistive Lateral Accelerometer
2-Axis AFM Cantilevers for Surface Friction
Experiments and Thermomechanical Data Storage
Flow Visualization in Microchannels
Ultrathin Cantilevers for attoNewton Force
Detection
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Embedded SMA actuators

• Intial experiments with epoxy and urethane
  polymers and various sacrificial
  supportmaterials have underscored the need
  tobuild in disposable fixtures for proper
  alignment.

Shape Memory Alloy wire with water cooling
channels
Epoxy
acrylic
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Embedded sensor example pressure sensor unit
for pneumatic actuators
PC board CAD file for commercial MEMS pressure
transducer instrumentation
Screen shot from SDM CAD environment several
steps in the building block design/fabrication
sequence for the embedded pressure sensor package
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Embedded sensor example (continued)
A batch of four parts during the final machining
step. Part material is urethane (yellow).
Sacrificial support material is wax (red),
filling cavities and encasing the circuit leads
to protect them.
Completed pressure sensor unit ready for
connection to a pneumatic actuator.
Fabrication instructions archived at
http//cdr.stanford.edu/dml/biomimetics/documents
.html
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Approaches to design with layered shape
manufacturing
Usually people think of taking a finished CAD
model and submitting it for decomposition and
manufacture
Example the slider-crank mechanism, an
integrated assembly built by SDM
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SDM process planning geometric decomposition for
tool access
build direction
Cross section of part material (gray) in support
material
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Decomposition into compacts and layers

• Several levels of decomposition are required

Complete Part
Compacts
Layers
Tool Path
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Testing for compactness
Z
There exists no point, p, on S which is an
inflection point with an undercut surface above
an upward-facing surface.
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Layers produced by automatic decomposer for
slider crank mechanism
Gray steel, brown copper support material
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Layered shape deposition - potential
manufacturing problems

• finite thickness of support material
• poor finish on un-machined surfaces
• warping and internal stresses

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Slider crank can be built entirely from two kinds
of primitives
Yellow part material, blue support material
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Merge algorithm for compacts (Binnard)
f (a,b )
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Building Designs from Primitives

• Here is the result of building slider-crank from
  primitives
• allows manufacturability analysis at design time

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Building a robot joint from a library of shapes
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Design for a prototype pneumatic knee joint built
from primitives (M. Binnard)
Magnetic Gear Tooth Sensor
Pneumatic Actuator
Link 1
Link 2
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Comparison with VLSI approach
SFF-MEMS
VLSI
Boxes, Circles, Polygons and Wires
Decomposed Features
SFF-MEMS Design Rules
Mead-Conway Design Rules