The Autonomous Pinger Unit (APU) is an electro-thermal drill with acoustic instrumentation developed for the project EnEx-RANGE in view of a future space mission for the sub-surface exploration of Saturn's moon Enceladus. A main goal is the development of navigation technology for an acoustic guidance system allowing maneuvering a probe through glacial ice. In total 13 APUs were built and tested in terrestrial analog scenarios on alpine glaciers. The APUs form a spatially distributed network that defines a system of reference for the navigation of the maneuverable probe to a point of interest. The APUs have a novel melting head, slow control systems, and a modern system-on-chip (SoC) module that controls the probe and processes the recorded data. The APUs use acoustic emitters and receivers to measure the transit time of acoustic signals between them, allowing for the position reconstruction of all APUs by trilateration. Several auxiliary sensors monitor the internal state of the probe and assist the position estimation. With this instrumentation, the APUs have the ability of dynamically optimizing themselves within the network by changing their position. This paper gives an overview of the developed APU hardware and presents performance results from the field tests.

中文翻译：

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EnEx-RANGE 中声学导航网络的自主 Pinger 单元：带有声学仪器的自主冰内融化探头

Autonomous Pinger Unit (APU) 是为 EnEx-RANGE 项目开发的带有声学仪器的电热钻，旨在为土星卫星土卫二进行地下探索的未来太空任务而开发。一个主要目标是开发用于声学引导系统的导航技术，该系统允许操纵探头穿过冰川。在高山冰川的地面模拟场景中，总共建造了 13 个 APU 并进行了测试。APU 形成一个空间分布的网络，该网络定义了一个参考系统，用于将机动探测器导航到感兴趣的点。APU 具有新颖的熔化头、慢速控制系统和现代片上系统 (SoC) 模块，用于控制探头并处理记录的数据。APU 使用声学发射器和接收器来测量声信号在它们之间的传输时间，从而允许通过三边测量对所有 APU 进行位置重建。几个辅助传感器监控探头的内部状态并协助位置估计。借助这种仪器，APU 能够通过改变其位置在网络内动态优化自身。本文概述了已开发的 APU 硬件并展示了现场测试的性能结果。