thesis/tech report

[Bartlett Mel]

The following thesis/TR is now available--about 50% of it is
dedicated to relations to traditional methods in robotics, and
to psychological and biological issues...


	MURPHY: A Neurally-Inspired Connectionist Approach to 
   	      Learning and Performance in Vision-Based
	 	      Robot Motion Planning
			

			 Bartlett W. Mel
	       Center for Complex Systems Research
	    Beckman Institute, University of Illinois

Many aspects of intelligent animal behavior require an understanding
of the complex spatial relationships between the body and its parts
and the coordinate systems of the external world.  This thesis deals
specifically with the problem of guiding a multi-link arm to a visual
target in the presence of obstacles.  A simple vision-based kinematic
controller and motion planner based on a connectionist network 
architecture has been developed, called MURPHY.  The physical setup 
consists of a video camera and a Rhino XR-3 robot arm with three joints 
that move in the image plane of the camera.  We assume no a priori 
model of arm kinematics or of the imaging characteristics of the 
camera/visual system, and no sophisticated built-in algorithms for 
obstacle avoidance.  Instead, MURPHY builds a model of his arm through 
a combination of physical and ``mental'' practice, and then uses simple 
heuristic search with mental images of his arm to solve visually-guided 
reaching problems in the presence of obstacles whose traditional 
algorithmic solutions are extremely complex.  MURPHY differs from 
previous approaches to robot motion-planning primarily in his use of 
an explicit full-visual-field representation of the workspace.  Several
other aspects of MURPHY's design are unusual, including the sigma-pi 
synaptic learning rule, the teacherless training paradigm, and the 
integration of sequential control within an otherwise connectionist 
architecture.  In concluding sections we outline a series of strong 
correspondences between the representations and algorithms used by 
MURPHY, and the psychology, physiology, and neural bases for the 
programming and control of directed, voluntary arm movements in 
humans and animals.


You can write to me: mel at complex.ccsr.uiuc.edu, or judi
jr at complex.ccsr.uiuc.edu.  Out computers go down on Feb. 13
for 2 days, so if you want one then, call (217)244-4250 instead.

-Bartlett Mel