EnEx-RANGE is part of the EnEx initiative, an initiative of the DLR Space Administration. RANGE is an acronym for „robust autonomous acoustic navigation in glacier ice“ (German: „Robuste autonome Akustische Navigation in Gletscher-Eis“). Participating RWTH institutes are the Physics Institute III B and Institute Cluster IMA/ZLW & IfU.

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Intelligent acoustic sensor network

EnEx-RANGE aims to develop an intelligent acoustic sensor network which allows for the navigation of an autonomous probe within an ice volume, e.g. an alpine glacier.
The intelligent acoustic sensor network will consist of separate Autonomous Pinger Units (APU), which are equipped with matched acoustic emitter and low noise acoustic receiver units. The APU carrier system includes a melting system enabling the APU to melt downwards into the glacier. A sophisticated, high performance data system records and processes the sensor data and controls the actuating elements. Furthermore, a reasoning system will carry out a distributed optimization of the sensor network based on its evaluation of current sensor data. Both, automated positioning via two-way acoustic signal exchange and autonomous evaluation of the signal quality is conducted. The latter information is used to determine the accuracy of the positioning and to assure an uniform acoustic coverage of the test area.

Navigation of the EnEx probe

Both the acoustic positioning as well as reconnaissance system developed within the former collaborative EnEx project will be enhanced within EnEx-RANGE.

The acoustic positioning system was developed to determine the absolute position of the EnEx probe based on trilateration. This system is to be adapted to the APU network and will be improved by an increase in sensitivity of the sensor technology. This improved performance will be achieved by the reuse of technology developed for the APU network. Overall this permits a reduction of measurement time while increasing the measurement accuracy. Furthermore, the degree of autonomy will be increased to enable the EnEx probe to act independently. This includes trajectory planning based upon the expected signal quality as well as autonomously initiated re-positioning in case of exceeded error tolerances.

The acoustic reconnaissance system acquires information about the surroundings of the EnEx probe based on sonography. The system emits directive acoustic signals and records the echoes from structural transitions such as obstacles (e.g rock fragments) or regions of interest (e.g. water-filled crevasses). The data provided by the acoustic reconnaissance system allows generating a map of the fore-filed of the EnEx probe, which can be used for navigation purposes. The sensor technology of the acoustic reconnaissance system is to be optimized to achieve a higher sensitivity as well as an expanded range. Furthermore, a performance enhancement of the electronics will enable an extension of local data processing.

System tests in water and glacier ices

System tests in water and glacier ice are carried out to review the accomplished improvements as well as the self-optimization of the APU network. Since glacier expeditions present a great logistic effort, measurements are conducted in water if possible. Measurements requiring water volumes up to about three cubic meters can be performed in the Aachen acoustic laboratory which is part of the Physics Institute III B. The swimming pool of the Ulla-Klinger-Halle as well as at the Rur Lake at RWTH Aachen Wildenhof venue can be used for experiments that require larger test environments. Especially the latter allows for spacious test scenarios similar to the ones planned for the glacier expedition in summer 2017. In summer 2018 the functionality of the intelligent acoustic sensor network in combination with the EnEx probe is to be demonstrated within the ice of an alpine glacier.


  • malcher_enex-range: Madeleine Malcher