Adaptive power switching technique for ultrasonic motion sensors

Abstract

Smart sensing technologies play a key role in the core of smart systems, which form the rapidly evolving internet of things. In this context, buildings' occupancy information is an important input that allows smart systems to be seamlessly aware of and responsive to the inhabitants, thus ensuring their comfort. Ultrasonic motion sensors are used to obtain occupancy information of indoor spaces. Although they provide a high accuracy as compared to other sensors, like Passive InfraRed, they require a higher power consumption. In this work, we propose an adaptive power switching technique, which we call power hopping. This technique allows ultrasound motion sensors to optimize their transmitter power level, in order to best fit their surrounding environment. The objective is to reduce the overall energy consumption of these sensors. We have tested our method using a sensor prototype, and the results show that, depending on the sensor's environment, a possible saving in the transmitter power can be achieved, which reached up to 78% in our experiments. We also derive an upper bound limit of the method's convergence time, and we propose an automatic sensing method to detect potential changes in the sensor's environment.