Transcript No Slide Title

Guiding questions
Low-Level
Control
MURI
High-Level
Control
How do we build robust biomimetic
structures and systems?
Fabrication
Shape deposition manufacturing of
integrated parts, with embedded actuators
and sensors (Stanford)
How do we build-in tailored
compliance and damping?
Structures with functionally graded
material properties (Stanford)
Effects of Compliance in simple running machine
(Stanford, Berkeley ME)
MURI
Fabrication
Biomimetic Structures
• Increase Robustness
• Integrated Sensing and Actuation
• Tailored Structural Properties
Boadicea Leg Design
(MIT 1995)
Contoured Multi-material Prototype
MURI
Fabrication
Shape Deposition Manufacturing
• Cycle of Material Deposition and Removal
• Complex 3D Geometry, Multi-materials
Part
Support
Deposit (part)
Shape
MURI
Fabrication
Shape Deposition Manufacturing
• Embed Components in mid-process
• Critical Geometry, Properties
Part
Support
Embedded Component
Deposit (part)
Shape
Shape
Deposit (support)
Embed
MURI
Design-by-Composition Interface
Fabrication
Library Components
Merged by Designer
Primitive A
Primitive B
Result Primitive
Primitives
Part Compacts
Support Compacts
MURI
Design-by-Composition Interface
Fabrication
Library Components
Merged by Designer
Primitive A
Manufacturing Plans Merged
By Algorithm
a3
b3
a2
b2
a1
b1
Primitive B
Result Primitive
Primitives
Part Compacts
Compact
List A
Compact
List B
Result Compact List
Support Compacts
MURI
Embedded Components
Fabrication
• Pneumatically-actuated Linkage
• Piston, Valve, Pressure Sensor, Fittings
Steel leaf-spring
Piston
Sensor and circuit
Spacer
Valves
Tubing Connector
Design Interface
Process Planning
MURI
Embedded Components
Fabrication
• Issues in Embedded Components (Cham et. al.)
– Fixturing, Retaining Functionality, Tolerances
Steel leaf-spring
Piston
Sensor and circuit
Valves
MURI
Fabrication
Embedded Components
• Reduction of Transport Volumes - Higher Bandwidth
• SDM moved us to new Control Regime
Air
Connector
Electrical Connectors
4 inches
MURI
Biomimetic Structures
Fabrication
• Multi-Materials Parts with different properties
• Arbitrary Geometry, Graded Materials
• Biological Inspiration
Contoured-Shaped Multi-Material Prototype
MURI
Fabrication
Graded Materials
• Graded Materials Very
Common Nature
• Few Examples of
Functionally Graded
Materials in Man-Made
Assemblies
MURI
Fabrication
Graded Materials
• SDM Allows Variability in
Compliance and Damping
throughout a Candidate
Design
MURI
Fabrication
Graded Materials
• SDM Allows Control of Material
Location and Property in a 3D space
Process Plan
Fabrication Cycle
MURI
Fabrication
Graded Materials
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•
Un-Actuated Five-Bar Leg Mechanism Illustrates
Benefits of Heterogeneous Material Properties
Flexure Joints Replace Pin-Joints to Add Compliance
and Damping
MURI
Fabrication
Graded Materials
•
•
•
Desired Performance of Structural and Flexural
Regions Very Different
Fabricating With Single Material Would Result In
Compliant Structural Regions or Brittle, Failure Prone
Flexures
Ideal Solution Requires Varying Material Properties
Between Different Regions of the Part
MURI
Fabrication
•
•
•
Graded Materials
Graded Interface Increases Surface Area, Resulting in
Increased Bonding
Mixing in Arbitrary Ratios Not Possible
Function Needs to Be Applied To Discretize the
Graded Regions Based Upon a Specified Tolerance
Parameter
MURI
Fabrication
Compliance for 1 DOF Machine
• Berkeley 1 DOF Walking Machine
• Four-Bar Linkages Represent Practical Application
Well Suited to Use of Graded Materials
MURI
Fabrication
Compliance for 1 DOF Machine
•
•
Reduce Assembly Complexity, Increase Robustness
Four-Bar Mechanism Utilizes Two Rotary Joints and Two Rocker Joints
Original Design
(Berkeley)
SDM Re-Design
MURI
Compliance for 1 DOF Machine
Fabrication
•Rocker Pin Joints Replaced With Flexural Regions to Introduce
Compliance and Damping
Original Design
SDM Re-Design
MURI
Compliance for 1 DOF Machine
Fabrication
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•
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New Design Features
With SDM
Geometry: Constant
Ground Contact
Replaced Pin Joints
With Flexural Region:
Introduced Compliance
& Damping
Leg Preflexes Defines
by Build Orientation
Future Analysis and
Experiments to Tune
Compliance to
Locomotion
Wrap up
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Status
Programmatic issues
Plans
Feedback
Status --
one year ago: 9.10.98
• “Building block” design/fabrication environment being tested and first
components with embedded sensors, electronics fabricated
• Meetings among SU, SRI, UCB to determine biomimetic actuators for
fabrication and testing at each site
• Designed and built apparatus for leg stiffness and perturbation
experiments
• Test-bed for compliance manipulation control set up.
• Experimental results on human adaptive control suggest a specific
design for manipulation
• Modeling and system I.D. applied to capture human walking on hills.
The results have been used to develop two-legged machines.
Comparison with biological models is underway.
Status
(today: 9.2.99)
• Detailed characterization of passive (fixed) and active components
(adjustable) of preflexes in cockroach.
• Gecko foot adhesion characterized using new micromachined sensors.
Sensors for insect leg forces being designed.
• SDM* environment used to create small robot limbs with embedded
sensing and actuation and functionally graded material properties.
• SDM robot limbs and compliant non-SDM robot undergoing testing
and comparison with results from insect legs.
• Compliant whole-arm-manipulator test-bed and minimum impedance
control strategies demonstrated. Human impedance testing in
progress.
• Model of human motor control learning tested and validated.
• Fast walker with biomimetic foot trajectory designed and tested; SDM
compliant limb retrofit underway.
*Shape Deposition Manufacturing
Plans
(see project structure chart)
Low-Level Biomimetic
Control
Robots
High-Level
Control
MURI
2nd generation SDM robots
with sensing and preflexes