# Implementation of Explosion Safety Regulations in Design of a Mobile Robot for Coal Mines
## 5 Conclusions  
A completely functional prototype of the reconnaissance mobile robotic system TeleRescuer has been built and thoroughly tested in various simulated and real conditions, including a training coal mine Queen Luiza in Zabrze, Poland--Figure 15. Tested were driving abilities (on various terrain material and quality, over obstacles of various sizes and shapes--perpendicular and at an angle, slalom, incline surfaces etc.), power abilities (pulling/pushing an obstacle), sensors accuracy, cameras placement, and image quality, etc. The tests showed some minor problems that should be improved in the following versions of the robot, for example, insufficient traction between the tracks and the ground, and complicated maneuverability in tight spaces during remote control based only on camera images. A detailed report from the tests is available in [36].  
Figure 14: Safety methane detector testing (CH\({}_{4}\) concentration [%] over time [s] in a testing chamber).  
Explosion safety is ensured by two independent protections according to Technical Report CLC/TR 60079-33 \"s\". The first protection is a flameproof enclosure that prevents methane from getting inside the body of the mobile robot. If this protection is damaged and a dangerous concentration of methane forms inside the body, the second protection (automatic gas detector) disconnects power from all electronic systems. This combination is valid for Group I, Category M1 because the whole system is fully operational even in environments with methane concentration and turns off only when the first protection is breached.  
The proposed solution of explosion safety was evaluated by a specialized certification authority (OBAC Institute for Research and Certification Ltd., Gliwice, Poland) and several minor modifications were recommended in the evaluation report, but the overall concept was approved. The outcome of this process was, however, only a qualified opinion, the robot was not officially certified for explosion safety yet (the certification is very expensive and getting a full certification was not one of the goals of the project). Physical destructive tests of the flameproof enclosure (Section 4.3) were not performed at this stage.  
The process of designing such a complex system (a reconnaissance mobile robot) in conformity with the very strict regulations that are related to explosion safety proved to be very difficult and demanding. It is highly recommended to discuss partial steps and decisions regularly during the process with a specialized authority.  
Future work on the system will include implementation of the proposed minor modifications and improvements of construction of the robot, control system algorithms, and user interface regarding observations and feedback achieved during the final tests.  
Conceptualization, P.N., T.K. and J.B.; Data curation, Z.K.; Formal analysis, Z.K.; Funding acquisition, W.M.; Methodology, A.R.L.; Project administration, P.N. and W.M.; Software, T.K.; Supervision, P.N.; Validation, P.N.; Visualization, T.K.; Writing--original draft, P.N., T.K., J.B. and A.R.L.; Writing--review & editing, P.N. and T.K.  
The project has been carried out in a framework of an EU programme of the Research Fund for Coal and Steel under the grant agreement No. RFCR-CT-2014-00002, by Polish Ministry for Science and Higher Education from financial sources that constitute the public aid in years, 2014-2017 assigned for an accomplishment of an international co-financed project; and partly supported by the European Regional Development Fund in the Research Centre of Advanced Mechatronic Systems project, project number CZ.02.1.01/0.0/0.0/16_019/0000867 within the Operational Programme Research, Development and Education.  
The authors declare no conflict of interest.