Adaptive Output Feedback Control of a Flexible Base Manipulator
An existing inertial damping mechanism by neural network-based adaptive
control, for controlling a micromanipulator that is serially attached to a
macromanipulator. The objective of the control design is to compensate
for the flexibility of the macromanipulator, and suppress vibrations in
inertial tip-positioning. In the test-bed, the micromanipulator is
mounted at the tip of a cantilevered beam which resembles a
macromanipulator with its joint locked. The inertial damping control
combines acceleration feedback with a separately designed position control
for the micromanipulator. There were several design challenges that had
to be faced from an adaptive control perspective. One challenge was the
presence of a non-minimum phase zero in an output feedback adaptive
control design setting in which the regulated output variable has zero
relative degree. Other challenges included flexibility in the actuation
devices, lack of control degrees of freedom, and high dimensionality of
the system dynamics.
Experiments
Whereas an joint controller without compensation for the base flexibilities results in a long settling time, an inertial damping controller adds acceleration feedback to damp unwanted vibrations and reduces the settling time significantly (movie, 4.7MB)
However, when the inertia of the tip is increased by five leads, the existing control system goes unstable because of abnormal operating condition. With a NN augmented, the inertial damping controller remains effective (movie, 7.4MB).
Also in an extreme configuration which is beyond the operating region of the inertial damping controller, adaptation enhances robustness and keeps the control system stable ([movie][FRex.avi], 9.9MB)
Flexible-base manipulator is located at Intelligent Machine Dynamics
Lab., Mechanical Engineering, Georgia Tech.
Collaborators.
The research was carried out in collaboration with Dr. Lynnane George
and
Dr. Ryan Krauss
when they were research assistants in [Mechanical
Engineering][http://www.me.gatech.edu/] at Georgia Tech under supervision of
Prof. Wayne J. Book.