Abstract
In this paper, an object localization and tracking system is implemented with an ultrasonic sensing technique and improved algorithms. The system is composed of one ultrasonic transmitter and five receivers, which uses the principle of ultrasonic ranging measurement to locate the target object. This system has several stages of locating and tracking the target object. First, a simple voice activity detection (VAD) algorithm is used to detect the ultrasonic echo signal of each receiving channel, and then a demodulation method with a low-pass filter is used to extract the signal envelope. The time-of-flight (TOF) estimation algorithm is then applied to the signal envelope for range measurement. Due to the variations of position, direction, material, size, and other factors of the detected object and the signal attenuation during the ultrasonic propagation process, the shape of the echo waveform is easily distorted, and TOF estimation is often inaccurate and unstable. In order to improve the accuracy and stability of TOF estimation, a new method of TOF estimation by fitting the general (GN) model and the double exponential (DE) model on the suitable envelope region using Newton–Raphson (NR) optimization with Levenberg–Marquardt (LM) modification (NRLM) is proposed. The final stage is the object localization and tracking. An extended Kalman filter (EKF) is designed, which inherently considers the interference and outlier problems of range measurement, and effectively reduces the interference to target localization under critical measurement conditions. The performance of the proposed system is evaluated by the experimental evaluation of conditions, such as stationary pen localization, stationary finger localization, and moving finger tracking. The experimental results verify the performance of the system and show that the system has a considerable degree of accuracy and stability for object localization and tracking.
Highlights
In many sensing technologies, object localization and tracking with range measurements have received significant attention because of their importance in many applications, such as obstacles avoidance, smart surveillance, human–computer interaction, safe sensing in factories, and autonomous navigation [1,2,3,4,5,6,7,8,9,10]
Aiming at the problem of object localization and tracking, this paper focuses on the construction of an object localization and tracking system based on an ultrasonic array
An ultrasonic array system consisting of one transmitter and five receivers for object localization and tracking is proposed in this paper
Summary
Object localization and tracking with range measurements have received significant attention because of their importance in many applications, such as obstacles avoidance, smart surveillance, human–computer interaction, safe sensing in factories, and autonomous navigation [1,2,3,4,5,6,7,8,9,10]. The system can locate the target by calculating the distances of ultrasonic echo signals between the sensors and the target. In this system, envelope extraction, TOF estimation, and object localization are three key issues. Several methods for envelope extraction and TOF estimation are presented in the literature. A sensing system is designed in [11], which uses the waveform of reflected ultrasonic signals to obtain additional information about the environment, and constructs a signal classification system for objects of different materials. The Hilbert transform is used to extract the envelope of the echo signal of ultrasonic, and the traditional threshold detector is used to estimate the TOF, which can capture the echo shape reliably and accurately. The Hilbert transform method is not effective because it uses fast
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