Stochastic Modeling of Wireless Energy Transfer with Applications in Wireless Displacement Sensing of Structures

Wireless communications are being utilized in nearly every field of work and impact virtually everyone\u27s daily life. With the increased use of wireless sensors, the difficulty of powering them becomes more apparent. One emerging technology is the use of wireless energy transfer which utilizes either a designated transmitter or harvests otherwise wasted energy. Since the amount of transferable wireless energy is limited modeling and simulating a system\u27s probability of operation is desired in order to maximize the run time of the sensor. These simulations allow for the investigation into the impact of a smart scheduling algorithm that can determine the ideal time to transmit a signal and consequently maximize the operational probability. In addition to the investigations into wireless energy transfer simulations, NASA is interested in using wireless displacement sensor for ground tests of structures such as fuel tanks and other spacecraft components. By converting the data lines from wired to wireless, several miles of cabling per structural test wouldn\u27t need to be installed saving significant time and materials. The designed sensor is to have a sampling rate of 1-100Hz with a measurable accuracy of at least 3 thousandths of an inch. A test bed is designed and built to accurately move an armature of a displacement sensor through the operational range in a repeatable fashion. Testing is conducted on an RDP D2/200a linear variable displacement transformer (LVDT) to compare operational performance in both wired and wireless configurations. Test results are presented and conclusions are drawn regarding the possibility of switching existing wired hardware at NASA with equivalent wireless powered units. Prototypes of the wireless displacement sensor are constructed and tested in the WiSe-Net lab at the University of Maine. In addition the wireless sensor prototype was tested at NASA MSFC to compare the performance to their existing wired displacement sensor system

Stochastic Modelling of Wireless Energy Transfer

This study investigates the efficiency of a new method of powering remote sensors by the means of wireless energy transfer. The increased use of sensors for data collection comes with the inherent cost of supplying power from sources such as power cables or batteries. Wireless energy transfer technology eliminates the need for power cables or periodic battery replacement. The time and cost of setting up or expanding a sensor network will be reduced while allowing sensors to be placed in areas where running power cables or battery replacement is not feasible. This paper models wireless channels for power and data separately. Smart scheduling for the data channel is proposed to avoid transmitting data on a noisy channel where the probability of data loss is high to improve power efficiency. Analytical models have been developed and verified using simulations