遥控连续采矿机在薄煤层中的应用外文文献翻译

英文原文Telecontrol of a continuous mining machine in thin coal seamsAugust J. Kwitowski, Albert L. Brautigam, and William D. MonaghanU.S. Department of the Interior Bureau of Mines Pittsburgh Research Center Pittsburgh, PA 15236Abstract-Telecontrol is a technology providing significant safety improvements in mining, by relocating machine operators hundreds of meters away from the immediate health and safety hazards. The U. S. Bureau of Mines recently developed and patented a telecontrol system for underground room-and-pillar mining. This system features near-real-time closed-loop control. A demonstration system was constructed that can be wed in thin-seam applications down to 914 mm. Details are provided on he developed telecontrol system, with the emphasis placed on the programmable logic controller-based electronic control system.1 IntroductionIn remote control continuous mining, the operator does not normally sit on the machine. This operator is typically located 3.05 - 15.24 m from the working face and communicates with the machine using a hard-wired pendant control or a radio transmitter with complement machine-based receiver. The operator receives direct operational cues via human senses like vision, hearing, and feel.Telecontrol (teleoperation), as used here, is the computer-based, distant control of mine machinery from a protected operator compartment located out of the line of site. The teleoperator responds to sensory information from a remote mining machine and makes corrections by moving control devices (usually switches). This initiates electronic control commands that, when received and interpreted, cause the appropriate remote machine function(s) to occur. Without question, telecontrol increases the safety of mining machine operators. This technology removes the operators from the hazardous immediate face area to a much safer location. In underground mining, the working face area contains many hazards. Unexpected roof falls can maim or kill miners instantly. Methane and coal dust explosions can be touched off with just a small spark or flame. Long-term health effects can result from miners breathing coal and silica dust and hearing loss can be caused by long-term exposure to noise pollution. Additional hazards are related to heavy mining equipment moving about in confined underground roadways that accommodate other workers. A goal of this work was to remove the operators of thin-seam continuous mining machines from these hazards.2 Previous workThe Bureau of Mines has been active in telecontrol research since 1979. A major milestone was achieved in 1989 when, following development and surface testing, a teleoperated highwall mining system (THMS) was evaluated at a cooperators field site 1. THMS subsystems included: (1) a Jeffrey Model 102HP thin-seam continuous miner, (2) a continuous haulage coal conveying system, (3) the teleoperators station, (4) the computer-based control system, and (5) support equipment located on the bench 2,3. The THMS could penetrate the highwall to a depth of 84 IIL. This was limited by the length of the continuous haulage system. A simple, line-of-sight laser alignment system was used to guide the THMS on a straight course. The THMS employed a unique, ergonomically designed, operator control station, shown in Figure 1, and required only three workers. To insure safety, none of the operating personnel were located in the mine entries. The THMS was developed as a combined effort of the Bureau and a cooperator, S.H.S., Inc. of Morgantown, WV. Fig. 1. Operator workstation The THMS was used as the basis for the design of a teleoperated, thin-seam, deep-mining system (TTDS). The TTDS used many of the same design features and hardware as the THMS. The most significant changes to the telecontrol system involved the teleoperators station and the electronic control system. A design goal was to fit the teleoperators station in an underground location where the vertical height was limited to 744 mm. The significant reduction in available vertical height between the THMS and the TTDS required substantial changes be made in the layout of the station and in the selection of display devices. The THMS used a distributed microcontroller system network based on the Intel BITBUS series. This system suffered from significant time delays between both (1) the activation of a control and the actuation of a machine function and (2) the detection of the change in a sensor data and the corresponding display of that change to the operator. This system was also difficult to program. These faults were corrected by the selection of a programmable logic controller-based electronic control system for the TTDS .3 Teleoperated thin-seam deep mining system Figure 2 shows a conceptual drawing of the complete TTDS. The TTDS fits the description for a mining system that was granted U.S. Patent No. 5,161,857 entitled Teleoperated Control System for Underground Room and Pillar Mining. Because the TTDS is to fit and operate in thin-seam (as low as 914 mm), deep, room-and-pillar applications, all the subsystems designs are unique. These subsystems include (1) a modified continuous miner, (2) a continuous haulage system, (3) a control station, (4) a computer-based teleoperating system, (5) a cable and hose handling module (6) an electrical, hydraulic, and air distribution module, and (7) a ventilation system. The ITDS is intended to be operated by two or more workers located in the belt entry.4 TTDS EquipmentThe teleoperated thin-seam continuous mining machine (CMM) is a modified Jeffrey Model 101MC. Modifications made for telecontrol included: (1) selection, packaging, installation and wiring of sensors, (2) packing and installation of a video subsystem, and (3) packing, mounting, and wiring of a slave computer and sensor processing electronics . The TTDS design includes a continuous haulage system; however, no decision on a specific system was made. Of the commercial units available, Joy Technologies 3 Flexible Conveyer Train (3FCT) appears suitable. Modification of the 3FCT to make it fully compatible with the design of the TTDS would include (1) lowering the profile to operate within 914 mm coal seams, (2) revising the tracking to follow automatically the CMM, and (3) providing function control through the telecontrol system. The teleoperators station houses the human operator and electronic controls. The operator sits in a reclined position. The height of the prototype compartment measures 838 mm, the width is 1524 mm, and the length is 2438 mm. Although the current compartment height is 838 mm, reducing the design of the profile by 75 mm is possible by lowering the operator control panel and seat configuration. The adjustable canopy vertical position and operators seat, permit the teleoperated system to be usable in higher seams. The planned location of this compartment is outby in the belt entry under supported roof. The station is not self-powered and requires other machinery to drag or carry it.Additional moduls are required for the TTDS. These include (1) a unit that contains motorized reels for winding and unwinding hoses and cables and (2) a unit to supply electrical, hydraulic, and pneumatic power to the other units.5 Machine Control SoftwareThe software requirements for the 545 module pivoted on achieving, as near as possible, real-time control of the CMM. The manual mode software and the input and output interface hardware duplicate all of the functions controlled by the operator with the original tethered pendant box. In addition, providing automated cutting cycle software relieves the teleoperator of repetitive machine operations. The software for the TTDS electronic control system was coded using TISOFT2 for the Siemens Simatic TT545 module. This package accommodates the usual programmable logic controller software including relay ladder logic (RLL), analog alarms, and proportion-integral-differential (PID) loops. TISOm2 also allows special function programs, written in a proprietary high-level structured language. A special function program consists of a set of instructions that can be called from PID loops, analog alarms, or the RLL program, much like a GOSUB subroutine in a BASIC program or a procedure in a C language program. The code for the manual mode software resides in RLL. With a RLL boolean execution speed of 0.78 ms/Kwords, near real-time is easily achieved. The code for sensor data acquisition and the automated cutting cycle was written using special function programs. The special function programs for sensor analog data acquisition are all cyclic with periods of 50 and 100 ms. The sensors related to the automated cutting cycle parameters are sampled every 50 ms while the others are sampled every tenth of a second. When the teleoperator turns on the automated cutting cycle switch, a special function program is called. The larger LCD monitor informs the teleoperator that the automatic cutting will begin. After an intentional five second delay, the system executes an automated cutting cycle. The automated cutting cycle consists of several chained steps. The occurrence of a terminating event from the previous step initiates the next automated cutting cycle step. The conclusion of a timer interval, or the value of acquired sensor data reaching a set threshold, triggers these step transitions. The teleoperator determines the automated cutting cycle parameters while operating in the manual mode. Before starting the automated cutting cycle, the teleoperator dials in these parameters via thumbwheel switches. The automated cutting cycle input parameters are CMM sump extension distance, upper auger boom cutting height, and lower auger boom cutting height limits. The LED digital readouts display the recorded upper and lower cutting heights which were determined by the teleoperator during the previous manual mode. The automated cutting cycle height limit parameters can be set to these values or others as dictated by the teleoperator s experience.After the teleoperator initiates the automated cutting cycle, the following sequence is performed:a) Retract the CMM sump frame to its outby limit. b) Turn on CMM dust sprays, if off. c) Turn on face equipment conveyors, if off. d) Cue the operator for consent to energize the CMM augermotors, if off. e) Set the CMM auger boom to predetermined upper cutting height limit. f) Float the CMM plow, if raised.g) Excluding pass one, tram the face equipment forward a distance equal to the predetermined sump extension distance limit. h) Cue the operator to adjust the face equipment position,if required, and give consent to proceed. i) Set the CMM sump frame to the predetermined extension distance limit.j) Lower CMM auger boom height to predetermined lower cutting height limit.k) Retract CMM sump frame to its outby limit. Go to step g.Another requirement of the automated cutting cycle software is to accommodate manual teleoperator intervention in case of a jammed conveyor on the CMM or haulage equipment. When a conveyor jams, the teleoperator manually activates the appropriate conveyor reverse control, suspending the automated cutting cycle (saving all parameters), to clear the obstruction. After the obstruction is cleared, deactivating the conveyor reverse switch resumes the automated cutting cycle from the point of interruption.6 Operator Interface Software The teleoperator is kept informed by the interface software. The interface software provides:a) Graphic representations of sensor data.b) Information for the automated cutting cycle.c) Diagnostic information to find problems and possible solution. d) Summaries for the operating period.The language used to write the operator interface software was MS C/C+ Version 7.0. The software runs on a 80386 module in the master controller base. Reading the 545 module memory over the common backplane bus achieves quick access to sensor data. In the THMS, a large and expensive array of digital bargraph displays was in the operator compartment to present sensor data. Since space is limited in the thin seam operator compartment, the sensor data is displayed on the large LCD monitor. An added benefit is that only selected sensor information is displayed at a given time, according to the operational sequence. This eliminates the clutter of the previous design and allows the teleoperator to concentrate on only the sensory information that is needed for a given operation. A switch labeled SCREEN DISPLAYS allows the teleoperator to override the automatic sequencing and presentation of information, as determined by the software. Switch settings allow the teleoperator to force displays that include (1) numerical presentation of all sensor data and (2)groupings of bargraph displays showing selected sensor outputs. Future revisions to the operator interface software will include the presentation of (1) diagnostic information with possible remedies, if any, and (2) performance information such as operating time, the number of automatic cutting cycles and average cutting height. When performing an automatic cutting cycle, the large LCD monitor shows the teleoperator procedural details about the operation. Most of this information is text that explains what is about to happen or what conditions caused the operation to abort. Reading PLC memory locations containing conditions flags determines the information to display. When the automatic cutting cycle is aborted, the software presents additional facts on the actions necessary to resume the cycle.7 Surface evaluationIn July 1991, initial surface testing of the PLC-based electronic control system was conducted at the Bureaus Pittsburgh Research Center. This testing demonstrated near real-time control of the Jeffrey l0lMC CMM. As shown in Figure 6, a 305 m shielded twisted pair cable connected the slave controller, which was located on the CMM, to the master controller, located at the remote operators station. Relay ladder logic was written for the 545 module in the master controller to control eight selected machine functions of the CMM. Several test teleoperators were requested to control the eight machine functions remotely. All reported no perceptible delays in machine operation. To quantify the on/off propagation delays for the PLC-based control system, laboratory tests were conducted. The master controller and slave controller were connected by a 305 m communication cable. The software utilized was the program written to conduct the eight-function remote control test of the Jeffrey lOlMC CMM. A one hertz square wave was applied to an input point on the master controller and a solid state relay, with alternating current load, was connected to a discreet output point on the slave controller. A Nicolet 3091 Waveform Analyzer was used to measured the delay times of the I/O point pair.For analog I/O propagation delay measurements, the PLC system consisted of one CTI analog to digital (MI) input module, located in the slave controller, and a CTI 2560 digital to analog (D/A) module located in the master controller. A simple relay ladder logic program moved eight input words of the A/D module to the corresponding eight output words of the D/A module. A function generator supplied an input signal from zero to fifty hertz at 10 volts peak to peak to the A/D input module. The output from the function generator and the D/A output module were connected to the vertical channels of the Nicolet Analyzer to measure the analog channel propagation delay. As shown in Table , the PLC-based system demonstrated improved response time about ten times faster than the Intel BITBUS distributed microcontroller system used with the THMS 4.A second surface test began during September 1992, and concluded October 1992. The remote operator controlled the Jeffrey lOlMC CMM using closed-loop control with the miner auger rotating in air. The connection between teleoperators station and the CMM was a 61 m cable assembly with four twisted pairs and two coaxial lines. Using the Siemens 545 PLC, the remote operator controlled CMM functions in near real time (measured 21 ms delay).The demonstration system, consisting of the modified CMM and the remote operators station, has remained intact and operational through May 1993. During refinement activities and demonstrations to interested parties, no system downtime has been attributed to the PLC-based electronic control system.Fig. 2. Teleoperated system for thin-seam room-and-pillar deep mines.8 ConclusionsWork conducted by the Bureau to-date demonstrates telecontrol is a viable method to remotely operate mining systems safety and effectively. Telecontrol tried in a developed highwall mining system appears promising for the deep mining application. In the teleoperated thin-seam mining system, improved electronic control systems increased the closed-loop system response to near real-time. If the development of telecontrolled mining equipment continues successfully and is accepted by the industry, this technology development will mark a significant milestone in achieving safer, more efficient, mining operations. Referencesl Kwitowski, A. I., A. L. Brautigam, M. C. Leigh. Teleoperation of a Highwall Mining System. Bureau of Mines RI 9420, 17 pp.2 Kwitowski, A. J., W. H Lewis, , W. D. Mayercheck, and M. C. Leigh.Computer-based Monitoring and Remote Control of a New Highwall Mining System. IEEE Transactions on Industry Applications, Volume 25, Number 4. July/August 1989, pp. 683-690.3 Kwitowski, A. I., W. D. Mayercheck, A. L. Brautigam. Teleoperation for Continuous Miners and Haulage Equipment. JEEE Transactions on Industry Applications, Volume 26,