NASA

ADVANCED CONCEPTS RESEARCH PROJECTS
PR-Number 10-86888 Appropriation: 806/70110
CMU Cooperative Agreement NCC7-7

Fractal branching ultra-dexterous robots
(Bush robots)

Final Report
(for November 15, 1997 - January 31, 1999)

Hans Moravec
Jesse Easudes

Carnegie Mellon University
Robotics Institute
5000 Forbes Avenue
Pittsburgh, PA 15213
USA

January 31, 1999



Table of Contents

Project Summary
Enabling Technologies
Recommendations
Summary Conclusion
Mechanical B=3 L=6 Model
Stereolithographed B=3 L=9 Model

Section 1: Motivation
Finer Fingers 13

Section 2: Bush Geometry
Fractal Parameters
Beyond Geometry
Fractal Finger Placement
Best Two Dimensional Bush Robot Geometry
Best Three Dimensional Bush Robot Geometry
Maximum Grip Size with Branching Level
Choosing vertex directions in rigid bush grips
Configuring Robot Bushes
Triangulating Bush Robot Skin
Stewart Platform Branch Actuation

Section 3: Graphics and Simulations
The Juggler
Arbitrary Pose Triangulations
Simulations
Left-/Right-handed fractal fill oscillation
Unsynchronized oscillations

Section 4: Investigation of Actuated Models
Two-Dimensional Bush Robot Prototype
Shape memory actuation for bush robot prototypes
Shape-Memory Branch Design Considerations
Simple Branch Fundamental Structure
Electrical Actuation
Mechanical Geometry
Mass loading
Electrical and Thermal Considerations
Control Wire Stresses
General Excursion to Force Relation
Test Joint Mechanics
Overview of Test Joint
Closeup of Test Joint
Test Joint Electrical and Thermal Design
Anchoring Nitinol Wires
Abandonment of Actuated Mechanical Prototype

Section 5: Fabrication of Structural Models
Stereolithography Machine
Graphics for Stereolithography Model
Photographs of Stereolithographed Model
Mechanical Model Design
Photographs of Mechanical Model

Appendix A: Design for Stereolithographed Model
Program Listing
Stereolithography File
Graphic Images of bush09.stl Model
Photographs of bush09.stl Model

Appendix B: Design for Mechanical Model
Assembly Instructions for Mechanical Model

Link to Quarterly Reports 1997-1999