# Implementation of Explosion Safety Regulations in Design of a Mobile Robot for Coal Mines
## 1 Introduction  
Despite the constant improvement of mining technology and ever more comprehensive knowledge of the geological composition of coal resources, there are still catastrophes that happen to underground coal mines. Thousands of miners die from mining accidents each year, especially from underground coal mining [1, 2]. Underground coal mining is considered to be much more hazardous than hard rock mining due to flat-lying rock strata, the presence of methane gas, and coal dust.  
The focus of the project \"System of the mobile robot TeleRescuer for inspecting coal mine areas affected by catastrophic events\" (supported by European Commission research fund Coal and Steel) was the development and realization of a system for virtual teleportation (virtual immersion) ofrescuers to the underground areas of a coal mine that have been closed due to a catastrophic event within them [3]. It was an international project managed by a consortium composed of the Silesian University of Technology (Gliwice, Poland), the VSB--Technical University of Ostrava (Ostrava, Czech Republic), the Universidad Carlos III de Madrid (Madrid, Spain), COPEX (Katowice, Poland), Simmersion GmbH (Gross-Siegharts, Austria), and Skytech Research (Gliwice, Poland) during years 2014-2017. All authors of this article are members of the consortium team.  
The inspection with use of a mobile robot should take place primarily in situations and places where the presence of a rescue team is absolutely precluded (e.g., after a decision to withdraw the team). In some situations, the robot could for a long time (e.g., a few or dozen days) remain in the danger zone as a remote measurement observatory. It seems to be recommended that the robot could be remotely controlled from a safe room (rescue base). It should be equipped with a set of cameras and a set of sensors for the analysis and recording of physical parameters of the mine and composition of the mine atmosphere. One should also consider the possibility of using a robot vehicle as a means of transport to provide e.g., a specialized equipment to/from the rescue base to/from the rescue team present in the danger zone (going to the zone or returning) or to the crew waiting for help.  
A mobile robot that is designed for harsh conditions must be able to properly operate in such conditions [4]. This includes not only a heavy-duty construction and good driving abilities, but primarily the robot must not make the situation even worse by, for example, causing a methane explosion. To secure this, most countries adopted certain regulations and standards for all devices that are intended for areas with potential risk of explosion, and these regulations must be indispensably followed.  
This article describes a practical application of said regulations for the mobile robot TeleRescuer. After the initial overview of the related legislation in the main world regions and analysis of existing mobile robots for similar tasks, TeleRescuer is introduced by a brief description of individual subsystems. Then follows the main part of the article--implementation of explosion safety regulations that begins by selecting the overall concept of protection, which is then described in detail (separation of electrical components into galvanic isolated subsystems; flameproof enclosure with an example of the performed stress analyses; automatic safety gas detector; and, other protections).