Engineering, Technology & Applied Science Research Vol. 8, No. 4, 2018, 3255-3259 3255 www.etasr.com Donza et al.: A Simple Electronic Circuit for an Automatic Train Safety Stop System A Simple Electronic Circuit for an Automatic Train Safety Stop System Andre Donza Department of Electrical Engineering Federal University of Para Department of Trains Maintenance, Brazilian Company of Urban Trains (CBTU), Recife, Brazil andredonza@cbtu.gov.br Riley Jones Laboratory of Electronics Brazilian Company of Urban Trains (CBTU), Recife, Brazil rileyrupert@cbtu.gov.br Rafael Teixeira Department of Trains Maintenance Brazilian Company of Urban Trains (CBTU), Recife, Brazil rafaelteixeira@cbtu.gov.br Bruno da Silva Department of Trains Maintenance Brazilian Company of Urban Trains (CBTU), Recife, Brazil brunogsilva@cbtu.gov.br Abstract—A particular safety system known as “dead man’s circuit” detects the presence of human command in the conduction of the trains operated by the Brazilian Company of Urban Trains (CBTU) in Recife, Brazil, thus consisting a security mechanism that makes automatic braking of any train composition circulating in the transportation system of the city feasible in incidents of loss or apparent loss of driving. Originally, the electrical signal indicating human control in the conduction of the vehicles came from the descent of the traction lever in the driving cabins, which caused the switching of a pair of electrical contacts. Given the importance of the system and the need to avoid repetitive strain injuries to drivers, the need to push the traction knob was eliminated by the use of an electronic device developed by an outsourced company and deployed in the trains of the older fleet. However, the high failure and downtime rates associated with the circuit acquired from the referred contracted company caused the need to develop a more robust and maintenance-friendly design for the dead man’s system. In fact, despite the good performance of the purchased system, the strength of the resin coating that accommodated the capacitive touch sensor assembly at the end of the traction lever prevented the corresponding electronic circuit from any access for research or corrective interventions. Thus, the content of this paper essentially presents the specifications and the description of operation of the alternative electronic circuit designed for the dead man’s system, which is operating normally without electrical defects in 4 old trains for almost a year. Keywords-urban trains; safety system; touch sensor; automatic braking I. INTRODUCTION A large number of techniques based on different maintenance approaches have been proposed to solve various types of maintenance problems [1]. These techniques and approaches must be adequate to specific situations and must be adapted to the singular needs of a company [2]. Obviously, in any approach, reliability assessments play a key role in determining whether or not a critical system or equipment should be replaced. The older fleet of the metropolitan trains operated by the Brazilian Company of Urban Trains (CBTU) in Recife, Brazil, is composed by vehicles from a Brazilian company, namely CISM. A particular system of these trains, known as dead man’s circuit detects the presence of human command in the conduction of the trains, thus consisting of a security mechanism that makes feasible in incidents of loss or apparent loss of driving, automatic braking of any train composition circulating in the transportation system of the city. The high failure and downtime rates associated to the dead man system developed by an outsourced company for the old fleet caused the need to deploy another design of this system. Thus, the current paper essentially presents the specifications and the description of operation of the alternative electronic circuit designed for the dead man’s system, which is operating normally without electrical defects in 4 trains since August 2017. II. HISTORY OF THE SYSTEM Originally, the electrical signal indicating human control in the conduction of the old railway vehicles of CISM came from the descent of the traction lever in the driving cabins, which caused the switching of a pair of electrical contacts, being continuously necessary for the driver to be with a hand supported on the traction knob to get or keep any train moving. Given the importance of the system and the need to avoid repetitive strain injuries to drivers, the need to push the traction lever to conduct the trains of the old fleet was eliminated by the use of a set consisting of two devices: a touch sensor, installed at the end of the traction handles, and an electronic main module, both shown in Figure 1, developed and installed by an outsourced company admitted by CBTU. Despite the ergonomic advantage, the implemented modification did not increase the reliability of the system and the maintenance quality. The strength of the resin coating that accommodated the touch sensor assembly at the end of the traction lever prevented the corresponding electronic circuit from any access for research or corrective interventions. Due to the lack of technical documentation of the circuits implemented by the outsourced company and the impossibility of accessing the sensor assembly without damaging it, the initial solution adopted to reduce the time of unavailability of trains for commercial operation due to failures in the dead man system was the acquisition of adjustable sensitivity capacitive cyl tra the res sim of agg po ma rev lim ele Fig sen Fig on the tog out dea exp and mo in cap con wi cap sen [4] fai mo tra in of fai the ele Engineerin www.etasr lindrical sens action levers on e CBTU's own sin encapsulat mplicity of the the capacitiv gravated by t ssible inversio ain control mo verse polariza mitations of sp ectrical or mec g. 1. Main mo nsor in the right g. 2. 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ELECTRICAL CONNECTIONS IN THE MAIN MODULE BOX Terminal Electrical Connections Cable Function 7A 7.A 24Vcc GD GD.A GD 2510.A 2510.A NC Contact 2510.B 2511.A NC Contact 2514.A 2514.A NO Contact 2503A 2503.A NO Contact 3 White Signal 2 Grey GD 1 Black 12Vcc a. Scheme of connections in the main module board.. VI. CONCLUSION The decision about replacing a critical system is sometimes controversial within the planning of the maintenance processes of a company. In fact, resolutions such as these consume time, resources, manpower, and should be carried out by objective considerations about the costs and benefits of the change. Therefore, its effects should also be revised so that new actions can be taken after the disclosure of any unwelcome unrolling. So far, no incident has exposed any relevant vulnerability of the new dead man’s system, which is operating normally in four trains for almost a year. There are no electronic components damaged in these vehicles and no complaints from drivers regarding the new traction levers. Although no unexpected event has happened, the operation of the new system continues to be monitored to evaluate the durability and the reliability of the system. In the path between the dead man’s system and the programmable logic controller of the brake control circuit, there is a device that can have its timing function incorporated through the CI 555 of the touch sensor. Future developments of the project include this modification. REFERENCES [1] R. Ahmad, S. Kamaruddin, “Application and Comparison of Three Maintenance Techniques for Replacement Decision Making – a Case Study in the Pulp Manufacturing Industry”, International Journal of Process Systems Engineering, Vol. 2, No. 2, pp. 135-153, 2012 [2] E. Viles, D. Puente, M. J. Alvarez, F. Alonso, “Improving the corrective maintenance of an electronic system for trains”, Journal of Quality in Maintenance Engineering, Vol. 13, No. 1, pp.75-87, 2007 [3] B. Osoinach, Proximity capacitive sensor technology for touch sensing applications, White Paper, FreeScale Semiconductor, 2008 [4] Z. Kappassov, J. A. Corrales, V. Perdereau, “Tactile sensing in dexterous robot hands – Review”, Robotics and Autonomous Systems, Vol. 74, Part A, pp. 195-220, 2015 [5] V. Gupta, A. Deb, “Speed Control of Brushed DC Motor for Low Cost Electric Cars”, IEEE International Electric Vehicle Conference, Greenville, USA, March 4-8, 2012 [6] K. Kotcherlakota, V. Chinta, “Smart Home Automation Based on 555 Timer”, International Journal of Engineering Research and Application, Vol. 6, No. 5, pp. 77-80, 2016 [7] H. Goyal, “Understanding of IC 555 Timer and IC 555 Timer Tester”, International Journal of Inventive Engineering and Sciences, Vol. 3, No. 2, pp. 4-6, 2015