DIIES Department, University Mediterranea of Reggio Calabria, 89126 Reggio Calabria, Italy.
HWA srl, Spin-off University Mediterranea of Reggio Calabria, Via R. Campi II tr. 135, 89126 Reggio Calabria, Italy.
Sensors (Basel). 2020 Jun 23;20(12):3548. doi: 10.3390/s20123548.
Increasing efforts toward the development of positioning techniques testify the growing interest for indoor position-based applications and services. Many applications require accurate indoor positioning or tracking of people and assets, and some market sectors are starting a rapid growth of products based on these technologies. Ultrasonic systems have already been demonstrating their effectiveness and to possess the desired positioning accuracy and refresh rates. In this work, it is shown that a typical signal used in ultrasonic positioning systems to estimate the range between the target and reference points-namely, the linear chirp-due to the effects of acoustic diffraction, in some cases, undergoes a shape aberration, depending on the shape and size of the transducer and on the angle under which the transducer is seen by the receiver. In the presence of such signal shape aberrations, even one of the most robust ranging techniques, which is based on cross-correlation, provides results affected by a much greater error than expected. Numerical simulations are carried out for a typical ultrasonic chirp, ultrasonic emitter, and range technique based on cross-correlation and for a typical office room, obtained using the academic acoustic simulation software Field II. Spatial distributions of the ranging error are provided, clearly showing the favorable low error regions. The work demonstrates that particular attention must be paid to the design of the acoustic section of the ultrasonic positioning systems, considering both the shape and size of the ultrasonic emitters and the shape of the acoustic signal used.
为开发定位技术而不断努力，证明了人们对基于室内位置的应用和服务的兴趣日益浓厚。许多应用需要准确的室内定位或人员和资产跟踪，一些市场领域正在基于这些技术快速推出产品。超声系统已经证明了其有效性，并具有所需的定位精度和刷新率。在这项工作中，我们表明，在超声定位系统中用于估计目标和参考点之间距离的典型信号——即线性线性调频——由于声衍射的影响，在某些情况下，会根据换能器的形状和大小以及换能器相对于接收器的角度而发生形状变形。在存在这种信号形状变形的情况下，即使是基于互相关的最稳健的测距技术之一，也会提供比预期误差大得多的结果。针对典型的超声线性调频、超声发射器以及基于互相关的测距技术进行了数值模拟，并针对典型的办公室环境进行了模拟，这些模拟使用学术声学仿真软件 Field II 获得。提供了测距误差的空间分布，清楚地显示了有利的低误差区域。这项工作表明，在设计超声定位系统的声学部分时，必须特别注意超声发射器的形状和尺寸以及所使用的声信号的形状。
