Novel battery-less wireless sensor for weigh-in-motion and traffic flow measurements

With the advent of ultra-low power sensor packages, there is renewed interest in harvesting vibration energy to power them, thus creating a self sustaining battery-less sensor system. The optimal algorithms previously developed in literature to harvest vibration energy are complex and hence require controllers that consume a significant amount of power. The relatively high power requirement combined with the inherent constraints on the implementations of these algorithms limit them to applications involving sustained vibration.;This thesis presents new control systems to maximize the amount of energy harvested from short duration vibrations. Only algorithms that can be implemented using simple ultra-low power analog electronic components are considered. The first algorithm termed "Fixed Threshold Switching", has been adapted from literature on harvesting energy from sustained vibration. The second and third algorithms are new optimal control algorithms termed "Maximum Voltage Switching" and "Switched Inductor" respectively. The three algorithms are theoretically evaluated and compared for a short duration vibration application and the "Switched Inductor" algorithm is found to be the most optimal algorithm.;The energy harvesting algorithms that have been developed are used to power a novel battery-less wireless traffic sensor and a novel battery-less wireless weigh-in-motion (WIM) sensor. Both the sensors can be embedded in the road without the need for power/data cables. The traffic sensor can measure traffic flow rate and vehicle speed and can be used for vehicle classification. Compared to existing inductive loop based traffic sensors, the new sensor is expected to provide increased reliability, ease of installation and low maintenance costs.;The new WIM sensor, in addition to having all the desirable characteristics of the traffic sensor, is an extremely inexpensive replacement to current WIM sensors. Both sensors use power only for wireless transmission and have ZERO idle power loss. Hence the sensors are expected to be extremely energy efficient. Experimental results on the traffic sensor validate the fact that adequate energy can be harvested from each passing vehicle to enable successful wireless transmission of data. Experimental results on the WIM sensor demonstrate that the new WIM sensor can make reliable weight measurements.