WP2 Sensor Technologies
There are two main strands in this work package. First there is the development of environmental sensors that will withstand serious incidents such as explosions or fires so that they are able to provide information to rescuers, following such an incident, before entering a mine. Second there is the adaptation of sensors and thermal imaging cameras so that they can be carried onboard the small unmanned vehicles that will be developed in WP3.
The work is divided into the following tasks:
T2.1 – Resilient, Survivable Sensors: Top-level Design
A novel type of environmental sensor will be developed which will be housed in a pod, recessed into the gallery roof, to prevent damage as a result of explosions or fire, and which will be deployed either automatically or manually by remote control, following an incident. The sensor will be self-powered, but connected to a power network under normal conditions, to allow continuous battery charging, and it will communicate as part of an LF/VLF mesh network.
First, the requirements of the unit will be defined in terms of the atmospheric constituents and other environmental factors to be sensed, and the option of adding a vital signs sensing capability will be considered. Then, a top-level design will be produced to include aspects such as the mechanical design including means of protection from the consequences of a serious incident, the method of deployment, the type of battery and the charging method to ensure long-term reliability with a requirement of minimal routine maintenance, third-party sensor selection, electronic control scheme, and the LF/VLF mesh transceiver.
A sensor could be capable of also acting as a node in an LF/VLF mesh network, of the type developed in T1.3, irrespective of whether it is also required to sense the environment at the same time. Consideration will be given, therefore, into whether or not two variants of the survivable sensor should be designed, one that can only act as a sensor and one that can also act as a mesh node.
T2.2 – Resilient, Survivable Sensors: Product Design & Laboratory Tests
Following on from the top-level design produced in T2.1, and a decision on whether to develop one or two variants of the resilient, survivable sensor, a detailed product design exercise will be conducted.
First, work will start on mechanical design of the sensor pod. In parallel with this activity, a means will be developed by which the sensor pod is installed into the gallery roof, with issues of cost and the ease and speed of installation being paramount.
Next, the detailed design of the electronics and software will be carried out. Following this, a prototype unit will be manufactured for testing purposes, supported by full product documentation.
As a final part of this task, initial laboratory tests will be conducted as an important preparatory phase to the field tests that will take place in WP6. Included here are tests into the unit’s survivability in extreme conditions.
T2.3 – Sensor Adaptation & Interfacing for Small Unmanned Vehicles
Sensors for fixed use in a mine represents a mature technology but adaptation to the state-of-the-art, and with requirements different from those in RFCS TeleRescuer, will be carried out in this task. This is necessary to meet the unique requirement of being able to carry the sensors onboard the very small unmanned exploratory vehicles – with a small load carrying capacity and possibly with low-bandwidth communication, these being necessary features of the vehicles that will be developed in WP3 – where the ability to deploy the vehicles early and quickly is the overriding priority.
First, the necessary sensor set will be selected and their output properties analysed. This analysis will provide essential information for the design of the sensor interface. It is anticipated that the sensor set will be similar to that of the TeleRescuer but with the probable addition of a seismic sensor that will be developed in order to analyse the seismic effects in the ground (seismicity/ human noise, etc.). This sensor, of course, would only be active when the unmanned vehicle is in a static position. A thermal imaging camera will also be included in the sensor set with size and weight being important criteria in its selection.
Next, a special sensor interface will be developed. This interface has to pre-process some of the data due to the lack of communication bandwidth or due to a totally missing communication link. The communication quality will vary continuously with time, depending on the vehicle position. In addition all sensor data have different importance for the rescue team. This requires special interaction between the sensor interface and the telemetry interface. These interfaces will manage the communication strategy (e.g. variable data density of single sensor channels) in cooperation with the communications network(s). This is necessary to maximise the volume of important information for the rescue team. In order to simplify system implementation and wiring, sensors will provide digitized data in standardised format, rather than analogue data, through some kind of short-range fieldbus. A miniature individual embedded sensor controller, in charge of power management for each sensor, as well as for digitising its reading (readings will be normalized using preloaded calibration data), will be designed and implemented. This sensor controller will, in turn, interact with the sensor interface.
The sensor interface will by designed to collect all the digitised data and combine them with the current position and a time stamp. The sensor interface will be designed to generate three different data streams: one for immediate transmission as rescue team information, one for unmanned vehicle control and one for data storage. The data stream which is generated for transmission has to be buffered, because the telemetry interface has to control the data flow and to set the data priority. Consideration will be given to integrating the sensors onto the interface board to make the whole assembly more suitable for being carried onboard very small vehicles.
Normal design techniques to meet the requirements of ATEX certification are not fully appropriate for the extremely lightweight equipment that will be needed for compatibility with the low payload capacity of the vehicles on which they will be carried. For this reason, the basic parts of the UAVs (motors and their drives, autopilot, communications and battery) will be ATEX compliant but some less critical systems will be designed to be automatically powered-down if an explosive atmosphere is detected. The decision on the protection modes for non-essential subsystems will be made in WP3 on a case-by-case basis.