Abstract : An intelligent locomotive anti-collision system, composed of infrared ranging, microcontroller control, audible and visual alarms, and hydraulic braking, features a simple structure and is easy to install and connect with both new and old locomotives. It can automatically and quickly bring locomotives to a stop before a collision occurs, completely preventing locomotive-train collisions during underground coal mine rail transport. This significantly reduces economic losses and social impact, improves the safety factor and production efficiency of coal mines, and is the preferred solution for underground main roadway rail transport in coal mines. Keywords: underground; electric locomotive; collision avoidance; intelligence; microcontroller; infrared Feasibility Study of Intellectualized Electromobile Anticollision System WANG Xiao-hong, NIU Guang-qin, HAO Hai-jun, BAO Yue-hua (Wangzhuang Coal Mine in Luhn Environmental Energy Developme nt Co., Ltd., Changzhi 04603 1, China) Abstract: The intellectualized electromobile anticollision system is build up by infrared ray distance measurement, monolithic machine control, acoustic-optic warning, hydraulic pressure braking and SO on, which have simple structure and easy to link with new or old electromobil. When before the dangerous of crash, it can stop quickly and placidly． This avoide the accident of electromobil crash cornpletely and reduced economic losses and social influence infinitely． Which has improved coal mine safety quotiety and productivity and is the preferred scheme for pit transports． Keywords: pit-bottom; electromobile; anticollision; intelligence; monolithic machine; infrared ray Underground transport roadways are the main arteries of mine transportation, and the safety of transport in these roadways is a prerequisite and foundation for safe production in coal mines. With the rapid development of the coal industry and the continuous rise in the coal market, underground transport in main roadways, which is closely related to raw coal production in coal mines, has become increasingly heavy. Measures such as increasing the number of transport vehicles and trips, or increasing vehicle speed are usually adopted to adapt. This has also brought many unfavorable factors and safety hazards. In particular, due to factors such as the locomotive driver's inattention, slow reaction, misjudgment, fatigue, drowsiness, irresponsibility, and switch misalignment or accidental switching, head-on collisions and rear-end collisions of locomotives in main roadways occur frequently. Head-on collisions, in particular, have very serious consequences due to the great power and inertia. They may damage the tracks, roadbed, vehicles, and transported equipment, and may even cause roof collapses, fires, and gas accidents. If vehicles transporting personnel collide, the consequences are even more serious, causing numerous injuries. Currently, locomotive braking generally relies on manual operation of either resistor braking or handbrake braking. This can easily lead to severe shaking or excessive braking, causing accidents. Such locomotive collisions are extremely dangerous and have devastating consequences, significantly impacting the normal and orderly safe production of coal mining enterprises. Therefore, the research and application of automatic anti-collision systems for underground locomotives has become an important and urgent task in coal mining. Based on years of experience, theoretical knowledge, and accident cases, and considering the characteristics of various vehicle anti-collision devices currently on the market, an intelligent underground locomotive anti-collision system solution has been designed. 1. Comparative Analysis Currently, most locomotive anti-collision devices rely on elastic bumpers to passively buffer and absorb some of the collision energy to reduce impact damage. However, their anti-collision effect is negligible in the event of a locomotive collision. While there are many products and articles on highway vehicle anti-collision alarms or braking devices in the market and in technical publications, few are actually used. Firstly, they all share the common feature of using infrared, ultrasonic, laser, or radio signals that are reflected back. The receiver processes the received signal and then issues an alarm or brakes. However, the underground environment of coal mines is unique, with narrow roadways, numerous bends and junctions, and the maximum distance between the roadway wall and the rail is less than 1 meter. When the locomotive travels through bends and side roadways, the electromagnetic waves or light emitted by the transmitter installed on the locomotive itself can easily be reflected by the roadway wall or passing vehicles, causing false alarms and malfunctions of the braking device. Secondly, the braking device relies on mechanical mechanisms such as handbrakes and motor levers, and the reaction speed can be slow or fast, resulting in unstable braking, which can also easily lead to vehicle derailment or equipment damage, and even personnel injury. Therefore, this type of braking device is unsuitable for use in underground coal mines and may also leave safety hazards. 2 System Features 1) The underground intelligent locomotive anti-collision system uses infrared light as the distance detection light source, which has strong anti-interference ability, high reliability, and is not affected by locomotive headlights, roadway lighting, miners' lamps, or other electromagnetic waves. The infrared transmitter and receiver are installed separately, and will not malfunction due to signals reflected by vehicles or roadway walls. 2) This system uses a single-chip microcomputer as the main controller, leveraging its powerful data processing and information handling capabilities to truly achieve intelligent and automated operation, greatly improving the system's reliability, stability, and intelligence level, thus ensuring safer locomotive operation. 3) When the locomotive enters different ranges of the infrared beams ahead, the system automatically uses the microcomputer to calculate the locomotive's current speed and relative distance to issue audible and visual alarm signals. If necessary, it activates the braking program to control the proportional solenoid valve's throttling, achieving soft braking before a collision occurs. The braking is both rapid and smooth, ensuring the safety of personnel and vehicle equipment, preventing secondary unnecessary personnel and equipment losses due to violent collisions or excessive braking. 4) Adding an LED or LCD display device would make the system more intuitive, complete, and powerful. 3 System Composition This intelligent locomotive anti-collision system mainly consists of an infrared transmitting unit, an infrared receiving unit, a main control unit, an execution unit, an audible and visual alarm unit, and a hydraulic braking unit. The infrared transmitting unit consists of an encoder modulator, carrier oscillator, electronic switch, transmitting tube, and focusing lens; the infrared receiving unit is an integrated infrared receiver head; the main control unit consists of a microcontroller, clock circuit, reset circuit, manual operation keyboard, and D/A converter; the execution unit consists of an opto-isolator and analog amplifier; the audible and visual alarm unit consists of a locomotive whistle and flashing alarm circuit; the hydraulic braking unit consists of a speed sensor, hydraulic oil pump, proportional solenoid valve, overflow valve, hydraulic cylinder, and brake push rod. 4. System Requirements 1) The "Coal Mine Safety Regulations" stipulate that "when two locomotives or two trains are traveling in the same direction on the same track, they must maintain a distance of not less than 100m. When transporting personnel, the braking distance of the train shall not exceed 20m." Secondly, the minimum radius of curvature of the main roadway curves in underground mines is generally around 25m. Therefore, this system calculates and sets system parameters based on the most dangerous scenario of traveling in opposite directions on the same track. In the infrared transmitting unit, the transmission distances of the three infrared transmitting tubes are adjusted to three different distances: alarm distance 80m, general braking distance 50m, and emergency braking distance 7m. 2) Considering the humid environment in coal mines, especially in summer when the track surface adhesion coefficient is lower and slippage is easy, the braking distance of the electric locomotive is set to three levels: alarm, 20m, and 2m. This ensures that the train has a certain buffer distance after braking to prevent slippage from affecting the locomotive's braking effect. Using the trigonometric formula α=2arctan(a/b) (where a is the maximum beam radius and b is the beam range, i.e., the maximum emission distance), the infrared tube emission angles are calculated to be 44', 68', and 8°. This means that when the maximum range of each transmitter is 80m, 50m, and 7m, the maximum beam diameter is 1m (the width of the electric locomotive). The beam perfectly covers the end face of the electric locomotive without affecting other vehicles, ensuring sensitivity and reliability. 3) Given that the microcontroller can only process one signal at a time, the duty cycle of the high-frequency modulation pulse of each transmitter must be controlled below 1/3, allowing them to work sequentially. This reduces operating current and power consumption, prevents signal interference, avoids false readings, and improves system reliability. 4) According to the "Coal Mine Safety Regulations," the maximum speed limit underground is 5 m/s for straight sections and 2 m/s for curves. The program parameters are set as follows: when the locomotive enters the set braking distance, the microcontroller calculates the braking acceleration using the formula a = V²/2L (where V is the current vehicle speed and L is the maximum braking distance). That is, the microcontroller automatically controls the braking acceleration between 0.6 and 4 m/s², issues a braking command, and adjusts the proportional solenoid valve to control the braking pressure, ensuring the train brakes smoothly to a stop within the specified displacement. 5. Working Principle The principle of the intelligent locomotive anti-collision system is shown in Figure 1. 1) The three different encoded signals of the infrared emitting unit's encoder modulator modulate the 38 kHz carrier signal, generating three different frequency modulation signals which are sent to the amplifier to drive three infrared emitting tubes, emitting infrared rays with three different codes. Based on the characteristic that a microcontroller can only process one signal at a time, the three amplifiers are controlled by electronic switches to conduct sequentially, ensuring that only one transmitting tube is working at any given time. This reduces operating current and power consumption, and avoids signal interference that could cause receiver misinterpretation. By selecting the transmitting tubes and adjusting the amplifier's transmitting power, the transmission distances are set to S1=80m, S2=50m, and S3=7m. By adjusting the focal length of each lens group, the beam angles are set to α1=44°, α2=68°, and α3=8°, ensuring that the beam diameter at the critical point of each transmission distance is 1m, perfectly covering the end face of the locomotive. This ensures reception while preventing interference with vehicles in adjacent lanes. The transmitting unit is installed in appropriate positions below the locomotive's headlights and the train's taillights. Since the underground rail transport locomotive and train travel in both directions without a head and tail, infrared transmitters are installed at both ends of the locomotive and the train (mine car). The infrared receiver is installed at the locomotive's head, directly opposite the transmitting unit. 2) The infrared receiver uses an integrated infrared receiver head, which is a module that integrates infrared reception, signal amplification, bandpass filtering, and comparison output. It is stable and reliable. It can be directly connected to the microcontroller port without an A/D converter. The receiver's signal incident angle is a minimum of 4°, so its signal reception will not be interfered with by infrared rays emitted by oncoming locomotives on both straight and curved tracks, unless they are traveling on the same track. 3) Using a microcontroller as the main control chip is the true meaning of achieving intelligent control. Using a microcontroller simplifies the circuit, reduces structural complexity, enhances functionality, automates detection and control, makes operation more reliable, and ensures safer operation. The programming and application of the microcontroller are not too difficult and will not be discussed here due to space limitations. 4) The infrared transmitter continuously emits three different ranges and codes of infrared waves forward sequentially, allowing the microcontroller to receive and determine the locomotive's current position, and then issue corresponding alarm or braking commands. When a locomotive, for some reason, enters the alarm distance S1 (80 m) of the vehicle ahead while traveling on the same track, the receiver receives the infrared signal emitted from ahead and quickly transmits it to the microcontroller. The microcontroller processes the data, analyzes and judges it, and then outputs it in two paths through photoelectric isolation. One path activates the locomotive's horn and flashing signal circuit, issuing an audible and visual alarm to remind the driver of this locomotive and the driver of the oncoming locomotive to slow down and maintain a safe distance. The other path quickly starts the hydraulic pump to prepare for braking. If the vehicle slows down and moves out of the alarm distance, the system automatically deactivates the alarm and disconnects the power to the hydraulic pump. If the locomotive does not slow down and continues to move forward, entering the normal braking distance S2 (50 m), the receiver transmits the received infrared signal to the microcontroller. After recognizing it as a braking signal, the microcontroller immediately issues a command to disconnect the control circuit of the locomotive's main motor, de-energizing the main motor and putting the train into a gliding state. Simultaneously, the system calculates and analyzes the current vehicle speed fed back from the Hall speed sensor, then issues a braking command according to the preset braking acceleration. The control current, after D/A conversion and analog amplification, adjusts the opening of the proportional solenoid valve, automatically adjusting the braking torque generated by the hydraulic pump. This gradually increases the output pressure of the hydraulic cylinder, achieving a smooth stop within 20 meters. If the locomotive detects a vehicle ahead while on a curve or with obstructed visibility at a distance, and is already within emergency braking distance (approximately 7 meters apart, where R is the radius of the track curve, calculated at 25 meters), the receiver receives the emergency braking infrared signal from the other vehicle. The microcontroller immediately issues an emergency braking command, controlling the opening of the proportional solenoid valve with a steeper braking acceleration. The larger braking torque allows the train to brake rapidly within 2 meters. This also prevents brake jamming due to emergency braking. 5) After braking, the reset button must be pressed to trigger the system to issue a release braking command and exit the braking state. This system prioritizes manual control over automatic control; pressing the manual brake button allows for normal braking at any time, eliminating the cumbersome operation of turning the brake handwheel, making it convenient and quick. 6. Conclusion Safety is an eternal theme in coal mining, and safe production is an important policy consistently upheld by the Party and the State. The high number of coal mine transportation accidents is mainly due to the numerous points, long lines, and wide areas covered by the transportation system, requiring all personnel underground to come into contact with transportation machinery and equipment. To reduce and avoid rail transport accidents, in addition to strengthening ideological education and technical training, improving the skills and qualities of locomotive drivers, and enhancing their sense of responsibility, the most fundamental solution is to improve necessary equipment and implement automated control. Only by combining human and machine management can locomotive accidents be effectively controlled and the goal of safe production achieved. The application of intelligent locomotive anti-collision systems is a powerful technical guarantee for achieving accident-free rail transport.