Abstract
The goal of this work was to set up a test environment
for active vibration control of rotors, to study the
dynamics of the system, and to design a control system
for controlling rotor vibrations. The principal idea was
to use a non-contacting magnetic actuator without a
load-carrying function. The test environment consisted of
a desktop rotor test rig, a magnetic actuator, and a
programmable control unit. The rotor was supported by
conventional bearings at the ends, and the control forces
were applied at the midpoint of the bearing span. The
work reports modal analysis and open-loop measurement
results on the test environment. The system was found to
vibrate excessively when the rotor was run close to its
bending critical speed at 40 Hz. Damping the system,
considered as the Jeffcott rotor, by means of a velocity
feedback controller was studied. The controller
parameters were selected on the basis of estimates
derived experimentally from the measured data. According
to the simulations and experiments performed, the
velocity feedback control system reduced the vibration
response significantly. The controller made it possible
to run the rotor across the critical speed. Another
controller, a feedforward system based on an adaptive
finite-impulse-response filter and the use of a reference
signal, was designed to compensate disturbances caused by
the mass imbalance in the rotor. The filter was adapted
by the least-mean-squares algorithm. The simulations and
experiments showed that the harmonic response due to the
mass imbalance was successfully compensated. The use of
the feedback system model improved the performance and
extended the operating range of the feedforward system to
super-critical conditions. The different roles of the
algorithms are pointed out: feedback control increased
the damping of the system, while feedforward control
compensated the disturbance at the frequency of rotation.
The forces required for damping the vibrations were low
compared with the mass of the rotor. The use of an
adaptive filter led to a considerable reduction in the
response, with a minor increase in the active forces
used. Results obtained elsewhere in similar test
environments are also reported in this work. The data and
experience acquired during the construction of the test
environment are discussed.
Original language | English |
---|---|
Qualification | Licentiate Degree |
Awarding Institution |
|
Supervisors/Advisors |
|
Award date | 30 Mar 2003 |
Place of Publication | Espoo |
Publisher | |
Print ISBNs | 951-38-6225-9 |
Electronic ISBNs | 951-38-6226-7 |
Publication status | Published - 2003 |
MoE publication type | G3 Licentiate thesis |
Keywords
- active vibration control
- rotors
- test environments
- magnetic actuators
- modal analysis
- damping
- measurements
- performance
- control