A range estimation system using coded ultrasound

Touchless human-computer interfaces, augmented reality, and mixed reality, need the location of user's limbs or direction of sight in real time, which can be provided by accurate Real Time Locating Systems (RTLS). RTLS can be realized using wireless accurate positioning sensors and multilateration techniques that compute the location of sensors from distance estimates between them and a set of reference points. The main practical difficulty relies in estimating, within the required accuracy, the distances between the reference points and the remote sensors. In addition, the majority of modern applications require miniaturized sensors with both severe size and power supply constraints, and thus limited computational power. In this work, a distance estimation technique using coded ultrasound and a miniaturized sensor is proposed. A prototype of the distance estimation system has been realized and characterized. It is composed of a beacon that emits a coded ultra-acoustic signal, a central processing unit (CPU), and a wireless distance sensor. The main advantages of the proposed system are the high miniaturization and low power of the remote sensor.