Title page for ETD etd-03042009-040756
|Type of Document
||Hollinger, James G.
||Autonomous tactile object exploration and estimation using simple sensors
||Master of Science
|Bay, John S.
|Abbott, A. Lynn
|VanLandingham, Hugh F.
- Pattern recognition systems
|Date of Defense
In order for robots to become more usefut they must be able to adapt and operate in
foreign or unpredictable environments. The goal of this thesis is to present an algorithm
that will enable a robot to autonomously explore its environment by touch and then
estimate the shape of objects it encounters. To demonstrate the feasibility and
functionality of such an algorithm, it was fully implemented on a MERLIN 6540
industrial robot. A unique compliant end-effector (consisting of a trackball mounted to
a force/torque sensor on a sliding mechanism) and a fuzzy logic force controller were
developed to overcome the difficulties inherent in force control on a stepper motor robot.
A Kalman filter based quadric shape estimator was then used to describe the objects
encountered in the MERLIN's workspace. The minimization of a cost function based on
the shape estimator's uncertainty guided the robot along an exploration trajectory designed
to produce the fastest converging shape estimate. Results of various exploration trials
using autonomous and preprogrammed trajectories are presented. In addition to shape
estimates, surface curvature measurements were also obtained. The unique end-effector
that provided compliance for the force controller was also able to measure the arc length
traversed on the object's surface. Arc length combined with surface orientation makes
it possible to determine local surface curvature.
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