Wahied G. Ali

A review on frequency tuning methods for piezoelectric energy harvesting systems

Piezoelectric energy harvesting technologies have received a great attention during the last decade to design self-powered microelectronic devices such as wireless sensor nodes. Piezoelectric energy harvester is a resonant system that produces maximum power output when its resonant frequency matches the ambient vibration frequency. The deviation from the resonance causes significant decrease in the power output. There are two possible solutions to compensate the effect of frequency deviation: widening the operating frequency bandwidth and tuning the resonant frequency. Tuning the resonant frequency is a more efficient technique for applications with single time varying dominant frequency. This paper presents a comprehensive review of frequency tuning methods for piezoelectric energy harvesting systems. Two categories generally investigated in the literature include manual and autonomous tuning methods. The recent developments of many tuning strategies are discussed and summarized.

Applications of Piezoelectric Materials

In this paper, the different applications of piezoelectric material (PZT) are surveyed such as: actuators, motors, transformers, sensors, and benders. The operation concept, advantages and disadvantages of these types are explained, that drive the suitable application of them. Moreover, the electrical and mechanical features of piezoelectric material are presented. These features are dynamic behavior, operation voltage, maximum force, and temperature effect. There are different piezoelectric material types such as ferroelectric materials and ferroelectric polymers that are presented and a comparison between them is achieved.

Embedded Control Design for Insulin Pump

This paper presents the design of an embedded control system for insulin pump. The insulin pump is an integrated component in any closed loop insulin delivery system for type 1 diabetes. The pump consists of three main components: micro-needles, insulin reservoir(syringe), and piezoelectric (PZT) linear servo motor. The actuated syringe has an injection back pressure that resists the linear motion of the driving PZT motor. This back pressure acts as a disturbance and leads to in accurate position and consequently an imprecise insulin dosage. Therefore, a highly precise positioning control on the pump is required to control the insulin dosage and to maintain the blood glucose level in its safe range. The proposed controller is designed using fuzzy logic as a nonlinear controller to compensate any non-modeled nonlinear ities in the system.The embedded controller for the PZT motor can be implemented using FPGA or microcontroller chip. This controller acts as a slave and responds to its master controller which controls the complete closed loop insulin delivery system.

Modeling and simulation of volture piezoelectric energy harvester

Piezoelectric material is used as an active material to convert vibration energy into electrical output and so called piezoelectric energy harvesting. The harvesters dynamic model depends on several parameters such as physical dimensions, geometrical structure, mechanical and electrical properties of the piezoelectric material. The development of theoretical model for analysis and simulation is a complex task whereas complete information about these parameters is not available from the manufacturers datasheet. In this paper, the dynamic model parameters are identified experimentally to reduce the modeling effort and to develop easily the equivalent circuit for the energy harvester (Volture, V21BL). The validation is achieved by comparing the estimated power outputs using simulation model with the real time measured values. The obtained results affirmed the potential of the adopted approach for modeling and simulation.

Identification and control for a single-axis PZT nanopositioner stage

In this paper, a second order transfer function of a single-axis PZT nanopositioner stage (P-752.21C) is identified around an operating point. The nonlinearity due to the hysteresis is modeled using look-up tables. The validation of the complete model is achieved experimentally. Two control approaches are developed. The former is a PI controller where the control parameters are tuned using Ziegler-Nichols method. The latter is a fuzzy controller like PI. The simulation results in MATLAB/Simulink are affirmed the potentials of the developed control methodologies.