The increasing demand for high-speed performance and low energy consumption has necessitated the design of lightweight mechanical systems. The active vibration suppression of a flexible manipulator is important in many engineering applications, such as robot manipulators and high-speed flexible mechanisms, because the flexibility of lightweight manipulators induces a vibration problem. Frequently, the optimal parameters determined for a certain control algorithm might not cover a wide range of operating conditions. Hence, we have proposed and developed a lookup table control method for a flexible manipulator that can tune itself to optimal parameters on the basis of the initial maximum responses of the controlled system and a genetic algorithm. The genetic algorithm is used to search for optimal parameters with regard to positive position feedback and thereby minimizes the objective functions determined from the initial maximum responses. Our lookup table, which has the optimal parameters of the positive position feedback as a function of the initial maximum responses, can be used in a real-time control algorithm.

Active vibration suppression of flexible manipulators is important in many engineering applications, such as robot manipulators and high-speed flexible mechanisms. The demand for a short settling time and low energy consumption of vibration suppression requires consideration of optimal control. Under a wide range of operating conditions, however, the fixed optimal parameters determined for a control algorithm might not produce the best performance. Therefore, to enhance performance, this paper suggests a lookup table control method for a flexible manipulator. This method can tune itself to the optimal parameters on the basis of initial maximum responses to the controlled system. In this study, a multi-objective genetic algorithm is used to search for optimal parameters with regard to positive position feedback to the control algorithm. In turn, with the optimal parameters, the multi-objective functions of the settling time and energy consumption during the vibration control of a flexible manipulator can be minimized. The simulation and experimental results both indicate that the energy consumption can be reduced significantly if the settling time is slightly increased.

Pre-stressed piezoelectric actuators such as RAINBOW, THUNDER™, and LIPCA have a curvature due to a mismatch of the coefficient of thermal expansion, which inevitably exists during the manufacturing process. This technical note provides an answer to the question of how their actuation displacement performance changes when the curved pre-stressed piezoelectric actuators are attached to a flat surface. Finite element analysis with the ANSYS™ program was used to calculate the stress distribution inside a LIPCA, one of the pre-stressed piezoelectric actuators, after the LIPCA was cured and attached to the flat surface. The change of actuation displacement performance can be explained in terms of the relation between the piezoelectric strain constants and internal stress. As a result of the curing and attachment to a flat surface, the two-dimensional stress state inside the piezoceramic layer leads to an expected increase of around 51% for the longitudinal piezoelectric strain constant. To confirm this result, we reconsider the experimental results of the actuation moment measurement of the LIPCA and bare lead zirconium titanate.

In this study, the pumping performance of a piezoelectric valveless micropump is simulated. The micropump, which was developed in the previous work, is composed of a four-layer lightweight piezocomposite actuator, a polydimethylsiloxane (PDMS) pump chamber, and two diffusers. The piezoelectric domain, the fluid domain and the structural domain are coupled in the three-dimensional simulation. We used ANSYS for the piezoelectric and structural domains and ANSYS CFX for the fluid domain. The effects of driven frequency on the flow rate have been investigated by simulating the flow characteristics for 10 Hz and 40 Hz driven frequencies. The flow rates with respect to driven frequencies up to 300 Hz have been calculated.