OCLC: 46575518
PROQUEST: 304398286
The main objective of this thesis is the development of high-precision positioning devices for a large range of displacements. As an actual representative of this class of devices, a piezoelectric rotary actuator was selected for the development. The basic principles of the design can, however, be easily applied to similar linear positioning devices. In addition to the high-resolution requirements, practicality of the design, reasonable-cost for manufacturing, suitability for commercialization, and good potential for further miniaturization are also among the other requirements.
Positioning devices with high accuracy and unlimited range of displacements are required by many industrial applications. High-precision micro machining, laser guidance systems, medical and physical instrumentation (for example, high-resolution microscopes) and microrobotics are some examples to mention.
The development of a piezoelectric rotary actuator with such targeted characteristics puts forward a number of theoretical and design problems. The most challenging components from a mechanical/ dynamics point of view are the flexure hinge mechanisms. These mechanisms are intended for the magnification of piezoelectric displacements. They are of complex shape, and they work in dynamically intensive regimes.
The development of an approach for stress analysis and the design of components with thin elastic bridges were the theoretical challenges of the work. The controller design for synchronization of multiple piezoelectric actuators in multi-micro-step regime constitutes the control part of the work. The last, but not the least challenges were the selection of the proper material for the piezoelectrics and flexure hinge mechanisms, and modelling the entire mechatronics system prior to the actual fabrication.
This thesis presents the entire process of the development from a novel idea to the design, fabrication, implementation of the experimental prototype, and laboratory testing.
The actuator proposed in this thesis is of stepper type; it generates a continuous rotary motion by combining very small angular displacements. The main advantages of the proposed actuator over the existing ones can be summarized as follows:
The actuator consists of three functional subunits, namely clamping, clutching and rotational flexure units. While the clamping and clutching units accommodate two multilayer piezoelectric devices, the rotational flexure unit includes only one of them. Step-wise continuous rotary motion is generated by driving these piezoelectric devices in a predetermined logic and by employing very small displacements, 30 µm, and extremely high blocking forces, 10000 N, generated by the piezoelectric devices.
The results of this thesis work verify the potential of piezoelectric actuation for high-precision positioning devices. The developed actuator has been modelled and fabricated based on the design approach suggested in this thesis. The unique flexure amplification mechanisms of the actuator as well as the entire actuator itself have been tested, and the results have been found to be highly promising. The agreement between the results of the physical experiments and those of the simulations validates the practical modelling approach suggested and utilized in this thesis. The proposed actuator has potential to provide even better characteristics with the final suggestions presented in the thesis.