Water scarcity for agriculture is one of the most important challenges to improve food security worldwide. In this thesis we study the potential to develop a low-cost controller for a small scale brackish desalination plant that consists of proven water treatment technologies, reverse osmosis, cation exchange, and nanofiltration to treat groundwater into two final products: drinking water and irrigation water. The plant is powered by a combination of wind and solar power systems. The low-cost controller uses Arduino Mega, and Arduino DUE, which consist of ATmega2560 and Atmel SAM3X8E ARM Cortex-M3 CPU microcontrollers. These are widely used systems characterized for good performance and low cost. However, Arduino also requires drivers and interfaces to allow the control and monitoring of sensors and actuators. The thesis explains the process, as well as the hardware and software implemented.

In retrospect we can see that from the last century, wireless electronic technology has been in a rapid state of development. With the popularity of wireless communication, the power amplifier demand is rising. In general, magnitude, maximum noise figure, minimum noise figure, efficiency, and output power are important indicators of the amplifier. The IC industry is exploring how to reduce the additional cost and improve the high-frequency performance. Therefore, designing a strong adaptability and high cost performance of the PA has become a priority. As these technologies advance, the power amplifiers need to have better integration, lower cost, and lower power dissipation. Also, some special requirements are being asked in some areas, such as multi-mode and multi-band. In general, people have to use several power amplifiers parallel to frame a multifunction chip. Each of them working at different frequencies of interest has to have separate matching network, design, and area; also, the diversity amplifier prices will increase with the number of amplifiers, and its cost is also changed. In this thesis, because Class E power amplifier has lower power dissipation, 100% ideal efficiency, simple circuit structure, and strong applicability, the Class E is used as power amplifier in main stage. …

Piezoelectricity crystal is used in different area in industry, such as downhole oil, gas industry, and ballistics. The piezoelectricity crystals are able to create electric fields due to mechanical deformation called the direct piezoelectric effect, or create mechanical deformation due to the effect of electric field called the indirect piezoelectric effect. In this thesis, piezoelectricity effect is the core part. There are 4 parts in the frequency output pressure transducer: two crystal oscillators, phase-locked loop (PLL), mixer, frequency counter. Crystal oscillator is used to activate the piezoelectricity crystal which is made from quartz. The resonance frequency of the piezoelectricity crystal will be increased with the higher pressure applied. The signal of the resonance frequency will be transmitted to the PLL. The function of the PLL is detect the frequency change in the input signal and makes the output of the PLL has the same frequency and same phase with the input signal. The output of the PLL will be transmitted to a Mixer. The mixer has two inputs and one output. One input signal is from the pressure crystal oscillator and another one is from the reference crystal oscillator. The frequency difference of the two signal will transmitted to the …

In this thesis, I present my work on the modeling and control of a motor system using the Lego EV3 robot. The overall goal is to apply introductory systems and controls engineering techniques for estimation and design to a real-world system. First I detail the setup of materials used in this research: the hardware used was the Lego EV3 robot; the software used was the Student 2014 version of Simulink; a wireless network was used to communicate between them using a Netgear WNA1100 wifi dongle. Next I explain the approaches used to model the robot’s motor system: from a description of the basic system components, to data collection through experimentation with a proportionally controlled feedback loop, to parameter estimation (through time-domain specification relationships, Matlab’s curve-fitting toolbox, and a formal least-squares parameter estimation), to the discovery of the effects of frictional disturbance and saturation, and finally to the selection and verification of the final model through comparisons of simulated step responses of the estimated models to the actual time response of the motor system. Next I explore three different types of controllers for use within the motor system: a proportional controller, a lead compensator, and a PID controller. I catalogue the …

In this thesis, we conduct a preliminary study on the controller design for directional antenna devices carried by drones. The goal of the control system is to ensure the best alignment between two directional antennas so as to enhance the performance of air-to-air communication between the drones. The control system at the current stage relies on the information received from GPS devices. The control system includes two loops: velocity loop and position loop to suppress wind disturbances and to assure the alignment of two directional antennae. The simulation and animation of directional antennae alignment control for two-randomly moving drones was developed using SIMULINK. To facilitate RSSI-based antenna alignment control to be conducted in the future work, a study on initial scanning techniques is also included at the end of this thesis.