(Georgia Institute of Technology, 2008-09)
Slatton, Andrew; Cohen, Daniel; Ding, Yang; Umbanhowar, Paul B.; Goldman, Daniel I.; Haynes, G. Clark; Komsuoglu, Haldun; Koditschek, Daniel E.
We are interested in the development of a variety
of legged robot platforms intended for operation in
unstructured outdoor terrain. In such settings, the traditions of
rational engineering design, driven by analytically informed and
computationally assisted studies of robot-environment models,
remain ineffective due to the complexity of both the robot
designs and the terrain in which they must operate. Instead,
empirical trial and error often drives the necessary incremental
and iterative design process, hence the development of such
robots remains expensive both in time and cost, and is often
closely dependent upon the substrate properties of the locomotion
terrain. This paper describes a series of concurrent but
increasingly coordinated software development efforts that aim
to diminish the gap between easily interfaced and physically
sound computational models of a real robot’s operation in a
complex natural environment. We describe a robot simulation
environment in which simple robot modifications can be easily
prototyped along and “played” into phenomenological models
of contact mechanics. We particularly focus on the daunting
but practically compelling example of robot feet interacting
granular media, such as gravel or sand, offering a brief report
of our progress in deriving and importing physically accurate
but computationally tractable phenomenological substrate models
into the robot execution simulation environment. With a
goal of integration for future robot prototyping simulations,
we review the prospects for diminishing the gap between the
integrated computational models and the needs of physical
platform development.
(Georgia Institute of Technology, 2007-08)
Moser, Jennifer M.; Carbone, Ignazio; Arasu, Prema; Gibson, Greg
Ancylostoma caninum is a globally distributed canine parasitic nematode. To test whether positive selection, population structure, or both affect genetic variation at the candidate vaccine target Ancylostoma secreted protein 1 (asp-1), we have quantified the genetic variation in A. caninum at asp-1 and a mitochondrial gene, cytochrome oxidase subunit 1 (cox-1), using the statistical population analysis tools found in the SNAP Workbench. The mitochondrial gene cox-1 exhibits moderate diversity within 2 North American samples, comparable to the level of variation observed in other parasitic nematodes. The protein coding portion for the C-terminal half of asp-1 shows similar levels of genetic variation in a Wake County, North Carolina, sample as cox-1. Standard tests of neutrality provide little formal evidence for selection acting on this locus, but haplotype networks for 2 of the exon regions have significantly different topologies, consistent with different evolutionary forces shaping variation at either end of a 1.3-kilobase stretch of sequence. Evidence for gene flow among geographically distinct samples suggests that the mobility of hosts of A. caninum is an important contributing factor to the population structure of the parasite.
(Georgia Institute of Technology, 2006)
Clark, Jonathan E.; Goldman, Daniel I.; Chen, Tao S.; Full, Robert J.; Koditschek, Daniel E.
Simple mathematical models or ‘templates’ of locomotion have been effective tools in understanding how animals move and have inspired and guided the design of robots that emulate those behaviors. This paper describes a recently proposed biologically-based template for dynamic vertical climbing, and evaluates the feasibility of adapting it to build a vertical ‘running’ robot. We present the results a simulation study suggesting that appropriate mechanical and control alterations to the template result in fast stable climbing that preserves the characteristic body motions and foot forces found in the template model and in animals. These design changes should also allow the robot to operate with commercially available actuators and in the same power to weight range as other running and climbing robots.