Modelling to Improve Positioning Accuracy in Urban Environments for Autonomous Vehicles

自动驾驶汽车(AVs)将导致交通运输领域的重大变革，并将在车辆设计、能源消耗、车辆拥有和道路利用(以及巨大的商业机会)方面实现效率。开发完全自动驾驶交通解决方案的一个关键挑战是导航通过目前基于GPS的定位系统的“盲点”，如停车场和地下道路。我们的企业合作伙伴(VitalAlert)拥有可以解决这一问题的技术。他们目前的产品允许使用甚低频(VLF)磁感应与井下矿工通信，这种磁感应可以穿透100米厚的岩石和土壤。VitalAlert正在寻求将这项技术用于大型汽车公司的AVS。其中一个关键挑战是VLF信号在穿过混凝土时会被衰减，但这个问题可以通过精确的建模和校准来解决，以获得准确的位置估计。为了进行这种校准，VitalAlert开发了一种有限差分时域法(FDTD)软件来估计甚低频信号的传播。虽然这种方法可以提供可接受的结果，但它的执行时间很长(对于一个50m x 50m x 20m的停车场，执行时间从几个小时到几天)。改善这种计算时间很重要，因为它限制了产品的商业潜力。在这个项目中，我们将开发一种有限元频域(FEMFD)建模技术，以实现更快(即几分钟)的准确建模。这反过来又将提高甚低频定位系统的商业潜力。我们的方法是基于在这项技术上的10年经验。

Autonomous Vehicles (AVs) are poised to cause major transformations in transportation, and will enable efficiencies in vehicledesign, energy consumption, vehicle ownership, and road utilization (as well as large business opportunities).A key challenge for developing fully autonomous transport solutions is navigation through locations that are currently "blind spots"for GPS-based positioning systems, such parking garages and underground roads.Our corporate partner (VitalAlert) has technology which could address this issue. Their current product allows communication withunderground mine workers using Very Low Frequency (VLF) magnetic induction, which can penetrate 100s of meters of rock andsoil. VitalAlert is pursuing using this technology for AVs with large automotive companies.One key challenge is that the VLF signals are attenuated when passing through concrete, but this problem can be solved byaccurate modelling and calibration to obtain an accurate position estimates. To do this calibration, VitalAlert has developed aFinite-Difference Time-Domain (FDTD) software to estimate the propagation of the VLF signal. While this method can provideacceptable results, it has long execution times (hours to days for a 50m x 50m x 20m parking garage). It is important to improvethis computation time, as it limits the commercial potential of the product.In this project, we will develop an Finite-Element Frequency Domain (FEMFD) modelling technique to allow faster (i.e. minutes)accurate modelling. This, in turn, will improve the commercial potential of the VLF positioning system. Our approach is based on 10 years of experience in this technology.