Optimal placement of distributed actuators on a multi-link flexible manipulator

Maxwell, Nigel, PhD (2004). Optimal placement of distributed actuators on a multi-link flexible manipulator PhD Thesis, School of Engineering, The University of Queensland.

       
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Author Maxwell, Nigel, PhD
Thesis Title Optimal placement of distributed actuators on a multi-link flexible manipulator
School, Centre or Institute School of Engineering
Institution The University of Queensland
Publication date 2004
Thesis type PhD Thesis
Supervisor Dr Sam Asokanthan
Total pages 271
Collection year 2004
Subjects L
230119 Systems Theory and Control
671401 Scientific instrumentation
Formatted abstract
In the aerospace industry, the expense of lifting materials to high altitude often demands that mass restrictions be enforced. Hence structures such as robotic manipulators for use in such tasks as the deployment and maintenance of satellites are typically designed to be very slender to accommodate these mass restrictions. However, reduced mass design approaches typically result in flexible structures vulnerable to vibration problems. These problems can detract from their functionability, and so methods for achieving vibration suppression when the system is limited by severe mass restrictions are of great interest. One such method is the application of distributed actuators for active vibration control of structures.

In this thesis, a methodology for the application of piezoceramic distributed actuators on a flexible robotic manipulator is presented. Since piezoceramics can significantly contribute to structural mass, it is desirable to minimise the quantity applied and hence to use only a few small actuators in locations of best effect. This introduces the problem of determining the optimal positions at which to place the piezoceramics. A new optimisation approach for determining the best positions at which to place a few piezoceramics is therefore developed and presented herein. The optimisation approach is applied to both single-link and two-link flexible manipulator problems modeled using physical parameters corresponding to the UQ_ARM experimental manipulator setup. The modeled system responses are then compared with empirical results taken from the experimental setup.

From the optimisation results obtained in this research, several conclusions are drawn. Firstly, the new optimisation approach described in this dissertation is compared against known optimal solutions and is determined to be successful in obtaining the minima of the optimal placement problem. Comparison of the optimal results for various relative weightings of the optimisation criteria demonstrates the relationships between each of the optimisation criteria. Consideration of the effects of shear on the modal characteristics of beams is also performed. As well, an inexpensive and simple procedure for the bonding of piezoceramics to beams is presented that gives a high degree of user control over the bonding layer thickness. Finally, a quick approach for approximating final solutions to the optimisation problem is developed and tested. This is useful when refining the choice of initial weighting values for each of the optimisation criteria to obtain a desirable system performance.
Keyword Manipulators (Mechanism)
Actuators
Piezoelectric devices
Piezoelectric ceramics
Additional Notes

Variant title: Optimal placement of distributed actuators

Document type: Thesis
Collection: UQ Theses (RHD) - UQ staff and students only
 
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Created: Fri, 24 Aug 2007, 18:37:04 EST