Appeal No. 2002-0049 Page 7
Application No. 09/317,538
Closed loop robotic deburring systems provide feedback control schemes
and contain sensors for monitoring either the position of the robot's arm or
cutting forces during deburring. The sensor signals are continuously compared
with the preprogramed position or force instructions for the robot arm, and are
used to generate an error signal which is fed back to the controller. The
controller adjusts the positioning of the robot arm to reduce the magnitude of the
error signal. An unfortunate drawback of a closed loop feedback control scheme
is the inability of the robot to respond in real time to the detailed features of a
burr. The action of the deburring system in response to the error signal will
always suffer a time delay due to the electrical and mechanical response times
of the system. The position of the deburring tool will oscillate about the desired
position as a result of this delay.
One simple solution to the problem of time delay associated with a closed
loop feedback control scheme is the utilization of an open loop control system. In
a simple open loop system, the desired tool path is programmed into the robot's
controller and is independent of output measurements. A disadvantage of an
open loop system is its inability to alter tool path in response to variations in part
geometry or to part misalignment.
In the Objects of the Invention (column 2), Dombrowski then provides that an object of
the present invention is "to provide a comparatively simple automated deburring system
which utilizes a piloted deburring tool to precisely machine part edges."
Dombrowski illustrates in Figures 1 to 3 an edge contouring system for
performing precision robotic deburring of workpiece edge. The edge contouring system
includes an industrial manipulator 12, such as an ADEPT ONE robot manufactured by
ADEPT Technology, Inc. The ADEPT ONE robot is a Selectively Compliant Arm for
Robotic Assembly (SCARA) type robot. Secured to the end of the robot's arm 14 is a
tool holder 10 and rotary cutting tool or deburring tool 30. The workpiece to be
deburred (not shown) is secured to the top surface of a rotary index table 18 rotatable
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