Design, control, characterization, and simulation of piezoelectric piloted hydraulic actuators

This work outlines three primary developments: an improved mathematical model for precision servovalves, application of the new servovalve model to a second phase actuator, and the system designed to control the camless engine actuator prototype. Each of these individual programs are closely related and represent the core of the recent actuation design, modeling, and control developments in the University of South Carolina's Advanced Actuators Research Group.; The improvement to mathematical modeling for servovalves was needed to better understand displacement as a function of time, especially for small-scale displacements and short time frames. This modeling improves previous work that did well to predict the overall performance of hydraulic servovalves but was unable to capture the details needed for camless engine actuators. The updated servovalve model captures the nuances of the internal geometry and allows for better prediction of displacement as a function of time and input parameters.; The new servovalve model was applied to a conceptual second phase design intended to improve upon the phase-1 actuator. The updated model allowed for the simulation of the new design, although its geometry greatly differs from the original actuator. The results of the simulation show a significant improvement to actuation times and indicate great promise for a second prototype camless engine.; The newly modeled servovalve was used for controller development. This development allows for easier application to the camless engine actuator prototype, and the overall feedback system was simplified compared to previous camless engine actuator control systems. This simplified control system was made possible because of improvements to the actuator itself.; The combination of improved models and control systems has allowed for the development of the working prototype camless engine based on piezoelectric piloting of a hydraulic servovalve. These new findings were applied to a second generation design and have laid the foundation for an overall improved actuator system, specifically designed for camless engines.