5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D RMain ideas:

• Use novel layered prototypingmethods to create compliant biomimetic structures with embedded sensors and actuators (Cutkosky, Kenny, Full)

• Develop biomimetic actuation and control schemes that exploit “preflexes” and reflexes for robust locomotion and manipulation (Kazerooni, Howe, Shadmehr, Cutkosky)

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D R

Building small robot legs with pre-fabricated components is difficult...

Motor

Leg links

Shaft

Shaft coupling

Boadicea leg

Electric motor/link

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D R

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.

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D R

Shape Deposition Manufacturing(SU/CMU)

• sensors • electronics

Shape

e.g., microcasting

(contouring)

e.g., Shot Peen

Deposit

e.g., CNC machining

(planing)

Embed

Stress Reliefe.g., thermocouple

stainless steel

sacrificial copper

internal copper

• CNC milling • CNC EDM • grinding

• microcast • gelcasting • 2-part mixtures • laser cladding • UV curing • plasma spraying • deposition welding • extrusion

• shot-peening • vibratory • preheating

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D R

SDM allows finished parts to be inserted at any point in the cycle

First layer part & support Second layer part & support

Insert bearings and second link Insert a sub-part

Final part deposition After support removal

Green link and red bearings are added as finished components

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D RSDM 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

MicroStructures and Sensors Lab (MSSL)

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

2-Axis AFM Cantilevers for Surface Friction Experiments and Thermomechanical Data Storage

Piezoresistive Lateral Accelerometer

Flow Visualization in Microchannels

Ultrathin Cantilevers for attoNewton Force Detection

Kenny

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D R

Epoxyacrylic

Shape Memory Alloy wire withwater cooling channels

Embedded SMA actuators

• Intial experiments with epoxy and urethane polymers and various sacrificial supportmaterials have underscored the need to

build in disposable fixtures for proper alignment.

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D R

Approaches to design with layered shape

manufacturingUsually 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

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D R

SDM process planning: geometric decomposition for tool access

Cross section of part material (gray) in support material

buil

d di

rect

ion

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS 11

C D R

Decomposition into ‘compacts” and layers

• Several levels of decomposition are required

CompletePart

Compacts Layers Tool Path

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D R

Testing for compactness

Build Axis

OKNot a

compact

~ ∃ = ⎮ <

p

ddZ ZS S

0 02

2

ƒƒ

There exists no point, p, on S which is an inflection point with an undercut surface above an upward-facing surface.

Z

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D R

Layers produced by automatic decomposer for slider crank mechanism

Gray = steel, brown = copper support material

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D R

Layered shape deposition - potential manufacturing problems

How mechanisms are built After support removal

• finite thickness of support material

• poor finish on un-machined surfaces

• warping and internal stresses

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D RSlider crank can be built entirely from two kinds of primitives

Yellow = part material, blue = support material

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D RMerge algorithm for compacts (Binnard)

f (a,b )

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D R Truth tables for Boolean operations on compact lists

cSPSS

a b cP P PP S SS P SS S S

P = part materialS = support materialc = f (a,b)

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D R

Building Designs from Primitives• Here is the result of building slider-crank from

primitives• allows manufacturability analysis at design time

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D R

SFF Object made up of Part and Support Compacts

What gets sent to the Manufacturing Service

Primitives + Merging Rules

The Final Geometry

What the Designer works with

Building a robot joint from a library of shapes

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D R

Link 1 Link 2

Pneumatic Actuator Magnetic Gear Tooth Sensor

Design for a prototype pneumatic knee joint built from primitives (M. Binnard)

5/17/981998 PI MEETING FOR LEGGED LOCOMOTION AND MUSCLE-LIKE ACTUATORS

C D R Decomposed Features

SFF-MEMS VLSIBoxes, Circles, Polygons and Wires

SFF-MEMS Design Rules Mead-Conway Design Rules

2

2

Wc/ >= 2

Minimum gap/rib thickness

d d

d

(top view)a)

Generalized 3D gap/rib

d2

(side view)b)

d2

Minimum feature thickness

d(m1,m2,m3)

(side view)e)

m1 m2 m3

d(m1,m2,m3,2)

m1 m2 m3

Comparison with VLSI approach