Section of Final Report: NASA ACRP NCC7-7, Bush Robots, Hans Moravec, Jesse Easudes

Appendix B: Design for Mechanical Model

We tried to choose the simplest and most economical approach to making a passively articulated three-way-branching bush robot model. Standard parts do not come in the scale steps required, so we loosened the requirements, and allowed up to 20% deviation from the norm sizes in structural members and joints. We designed a double-cone socket piece to contain three ball joints connecting a branch its three smaller twigs. We require 5 different scales of this part for our degree 6 bush:

Each such part is capped by a three-petaled sheet metal cover to hold in the ball joints. The upper portion of each ball and the twig it supports protrude through a hole in each petal sized to allow a +/- 45° swivel from the 45° normal of the cone orientation, allowing the twig to swing from parallel to orthogonal relative to the orientation of its parent branch. Here is a graphic of a fully filled level 6 mechanical bush model:

Photographs of Mechanical Model