This thesis presents a discussion of motion of a six-legged walking
machine following removal of one leg constraint. To take a step, one leg
must be lifted and placed at some other position. As soon as the constraint
provided by the leg is removed, however the machine begins to fall. This
falling motion can be represented as screw motion of the body center of
mass and of body-leg attachments.
First a study of body workspace of the machine was done with all six
feet on the ground. Body workspace is the intersection of kinematic and
force workspaces. Kinematic workspace is the volume in space where the
center of mass can be placed such that all joint angles of legs are within
specified limits; and force workspace is the volume in space where the force
in all legs is compressive. The affect of various foot positions, pitches and
heights of the center of mass were investigated to find a set of three
symmetric foot positions that might constitute acceptable intermediate
positions in a walking sequence.
Motion of the center of mass in the forward direction is limited in the
force workspace by two points at which the force on a pair of legs goes to
zero. With the center of mass at each of these two positions, the screw
parameters resulting from the release of force on one leg (front, middle and
hind individually) could be determined.
Dynamic simulation of these body and foot positions used the
commercial software SD/FAST. Code was written in C to do both static and
dynamic simulation of machine and merged with code generated by
SD/FAST. Code was also written in Auto Lisp to plot the falling motion of
machine.
Screw parameters found in this study were such that sustained
forward motion of the body could not be achieved using the falling motion
alone. Other measures such as extending one or more of the remaining five
legs would be needed for effective forward body motion. / Graduation date: 1994
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/35634 |
| Date | 19 October 1993 |
| Creators | Batra, Ajoy |
| Contributors | Fichter, Eugene F. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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