A novel explosion-proof walking system: Twin dual-motor drive tracked units for coal mine rescue robots

A new explosion-proof walking system was designed for the coal mine rescue robot(CMRR) by optimizing the mechanical structure and control algorithm. The mechanical structure innovation lies mainly in the dual-motor drive tracked unit used, which showed high dynamic performance compared with the conventional tracked unit. The control algorithm, developed based on decision trees and neural networking, facilitates autonomous switching between "Velocity-driven Mode" and "Torquedriven Mode". To verify the feasibility and effectiveness of the control strategy, we built a self-designed test platform and used it to debug the control program; we then made a robot prototype and conducted further experiments on single-step, ramp, and rubble terrains. The results show that the proposed walking system has excellent dynamic performance and the control strategy is very efficient, suggesting that a robot with this type of explosion-proof walking system can be successfully applied in Chinese coal mines.

Application of Dual Throttling Air-Conditioning System to Explosion-Proof Frequency Converter

An explosion-proof dual throttling air-conditioning system was put forward to solve the heat dissipation and internal dewing problems of explosion-proof frequency converter in the underground coal mine. This study investigated the feasibility and benefits of explosion-proof dual throttling cooling and dehumidification air-conditioning system applied to the explosion-proof frequency converter. The physical model of dual throttling air-conditioning system was established and its performance parameter was described by mathematical method. The design calculation of the system has also been done. The experimental result showed that the system reached the steady state at the refrigeration mode after running 45 min, and the maximum internal temperature of the flame-proof cavity was 31.0 ℃. The system reached the steady state at the dehumidification mode after running 37 min. The maximum internal relative humidity and temperature of the flame-proof cavity were 33.4% and 36.3 ℃, respectively. Therefore, the proposed system had excellent ability of heat dissipation and avoided internal dewing. Compared with water cooling system, it was more energy-saving and economical. The airflow field of dual throttling air-conditioning system was also studied by CFD simulation. It was found that the result of CFD numerical simulation was highly consistent with the experimental data.

A STUDY ON HEAT PIPE RADIATOR USED FOR THE COOLING OF THE HIGH-POWER THYRISTOR IN EXPLOSION-PROOF SHELL

The cooling of the high-power thyristor (HPT) in explosion-proof sbcll (EPS) used inmining pit has been a difficult problem for a long time. It has some spectal demands. According toheat pipe’s working principle, this paper introduced a kind of newly devcloped beat pipe radiatorSeveral HPT in EPS can be cooled by one beat pipe. In order to obtain the cooling and forced convection cooling , two dimensionless equations were obtained. This paper also studicd the refation between the surface temperature of HPT and the working electric current. The corresponding curvewas given out. Experiments shown that the beat pipe radistor introdued in this paper could effectively cool the HPT in EPS. It becomes a practical and valuable new technique.

Mobile platform of rocker-type coal mine rescue robot

After a coal mine disaster,especially a gas and coal dust explosion,the space-restricted and unstructured underground terrain and explosive gas require coal mine rescue robots with good obstacle-surmounting performance and explosion-proof capability. For this type of environment,we designed a mobile platform for a rocker-type coal mine rescue robot with four independent drive wheels.The composition and operational principles of the mobile platform are introduced,we discuss the flameproof design of the rocker assembly,as well as the operational principles and mechanical structure of the bevel gear differential and the main parameters are provided.Motion simulation of the differential function and condition of the robot running on virtual,uneven terrain is carried out with ADAMS.The simulation results show that the differential device can maintain the main body of the robot at an average angle between two rockers.The robot model has good operating performance.Experiments on terrain adaptability and surmounting obstacle performance of the robot prototype have been carried out.The results indicate that the prototype has good terrain adaptability and strong obstacle-surmounting performance.

EFT/B interference transmission model and method of anti-interference in a coal mine monitoring substation

Coal mining monitoring system has been enforcing tests for the immunity of Electromagnetic Compatibility(EMC) since 2006.However,not all monitoring substations can pass the Electrical Fast Transient/Burst(EFT/B) immunity test and the explosion-proof test simultaneously.In order to enhance EMC,the EFT/B interfere transmission model was presented at the substation power port,after the EFT/B test method was used to analyze the monitoring substation power ports.Hence,a low-pass filter was designed by using the simulation software PIPICE and an anti-jamming method was proposed by way of a parallel connection of the discharge interfere circuit and the low-pass filter.The improved complex EMI filter was made up of an interference discharge device and a filter.The dynamic equivalent circuit was proposed for the EFT/B immunity test.As a result,the monitoring substation has passed the EFT/B immunity and explosion-proof tests with the complex filter.It is concluded that the complex EMI filter has significantly enhanced the immunity of the coal mining monitoring system.

Dynamic parameter identification and nonlinear friction compensation method for safety perception of heavy explosion-proof robots

This article focuses on the problem of how to accurately calculate the joint control torques when the explosion-proof robot performs collision detection without sensors and gives a complete solution.Nonlinear joint frictions are incorporated into the dynamic model of a robotic manip-ulator to improve calculation accuracy.A genetic algorithm is used to optimise the excitation trajectories to fully stimulate the robot dynamic characteristics.Effective and applicable data filtering and smoothing methods are proposed and the Iteratively Reweighted Least-Squares method based on the error term is applied to identify the robot dynamic parameters.Compared with Ordinary Least-Squares method,the proposed algorithm improves the accuracy of joint control torques estimation.