The use of lightweight, thin flexible structures creates a dilemma in the aerospace and
robotic industries. While increased operating efficiency and mobility can be achieved by
employing such structures, these benefits are compromised by significant structural
vibrations due to the increased flexibility. To address this problem, extensive research in
the area of vibration control of flexible structures has been performed over the last two
decades. The majority of the research has been based on the use of discrete piezoceramic
actuators (PZTs) as active dampers, as they are commercial availability and have high
force and bandwidth capabilities. Many different active vibration control strategies have
previously been proposed, in order to effectively suppress vibrations. The synthesized
vibration controllers will be less effective or even make the system to become unstable if
the actuator locations and control gains are not chosen properly. However, there is
currently no quantitative procedure that deals with these procedures simultaneously.
This thesis presents a theoretical and numerical study of vibration control of a singlelink
flexible manipulator attached to a rotating hub, with PZTs bonded to the surface of
the link. A commercially available fibre optic sensor called ShapeTapeTM is introduced as
a new feedback sensing technique, which is complemented by a quantitative and
definitive model based procedure for selecting the individual PZT locations and gains.
Based on Euler-Bernoulli beam theory, discrete finite element equations are obtained
using Lagrange’s equations for a PZT-mounted beam element. Slewing of the flexible
link by a rotating hub induces vibrations in the link that persist long after the hub stops
rotating. These vibrations are suppressed through a combined scheme of PD-based hub
motion control and proposed PZT actuator control, which is a composite linear (L-type)
and angular (A-type) velocity feedback controller. A Lyapunov approach was used to
synthesize the PZT controller. The feedback sensing of linear and angular velocities is
realized by using the ShapeTapeTM, which measures the bend and twist of the flexible
link’s centerline. Both simulation and experimental results show that tip vibrations are
most effectively suppressed using the proposed composite controller. Its performance
advantage over the individual linear or angular velocity feedback controllers confirms
theoretical predictions made based on a non-proportional damping model of the PZT
effects. Furthermore, it is demonstrated that the non-proportional nature of the PZT
damping effect must be considered in order to bound the range of allowable controller
gain values.
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/1237 |
| Date | 30 October 2008 |
| Creators | Gurses, Kerem |
| Contributors | Park, Edward Jung Wook, Buckham, Bradley Jason |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
| Rights | Available to the World Wide Web |
Page generated in 0.0018 seconds