Title of Invention

"AN AUTONOMOUS CONTROL SYSTEM FOR SHEARER-LOADER IN UNDERGROUND LONGWALL COAL MINES"

Abstract

An autonomous control system for shearer-loader in underground longwall coal mines, which comprises in combination a cutting drum (1) driven by a cutter motor (2), charactersied in that the said cutter motor (2) being connected to a current sensor (4) and voltage transducer (5); the said sensors (4, 5) being connected to an analog to digital converter (ADC) unit (6) of a microprocessor based controller (7), the said ADC unit (6) also being connected to a haulage motor (8), variable speed drive (9) and firing/timing circuit (10) through a plurality of sensors/transducers such as current transducer (11), tacho sensor (12), frequency sensor (13) and voltage transducer (14); output of all the said sensors/transducers (4, 5,11-14) being connected to the said ADC unit (6), the said microprocessor (7) being connected to a display unit (15), digital to analog converter (DAC) unit (16) and regulated DC voltage supply (17); the said DAC unit being connected to the firing/timing circuit (10); the said cutter motor (2), regulated DC voltage supply (17), firing/timing circuit (10) and variable speed drive (9) being powered by AC main power supply (3); the said haulage motor (8) being connected to load (18).

Full Text

The present invention relates to an autonomous control system for shearer-loader in underground long-wall coal mines. The present invention particularly relates to a microprocessor based autonomous control system for shearer-loader in underground long-wall coal mines. The microprocessor based autonomous control system of the present invention will be particularly useful for shearer-loader in underground long-wall underground coal mines. Installation of the system of the present invention on a shearer-loader machine in an underground longwall underground coal mine would help in automatic control of load on its cutter motor while it is cutting coal face by controlling the haulage speed of the shearer-loader. This would help in controlling the fluctuation in torque experienced by the shearer-loader motor during its operations in the coalface primarily due to variations in seam strength parameters, rock intrusions and faults encountered in coal seams, and overcoming the problem of frequent stopping of the shearer-loader while it is overloaded. This would also help in reduction in rapid deterioration of winding insulation and premature failures, minimization of excessive vibrations, enhancement of life of machine components, decreasing down time hours and increasing the production and productivity of the mine. From a search of patent data bases and literature, it is seen that the hitherto known prior art generally related to control of shearer-loader loading in underground long-wall coal mine is disclosed in a German patent number DE3508243, titled "Circuit arrangement for shearer-loader for underground operations, equipped with a plurality of drive motors". Reference may be made to the said German patent number DE3508243, titled "Circuit arrangement for shearer-loader for underground operations, equipped with a plurality of drive motors", wherein a system has been described and claimed for controlling of shearer-loader loading in underground mine. The subject of the invention is a circuit arrangement for a shearer-loader which is used in underground mining and is equipped with a plurality of drive motors each of which has a current transformer and temperature sensor. The current transformers of all the drive motors are each connected directly to a common OR gate via in each case one rectifier and the temperature sensor. The said OR gate outputs an output signal when a temperature sensor signal occurs which indicates an unacceptable rise in the winding temperature or when one of the current transformers produces a signal which exceeds the admissible value, which output signal is fed to an electronic trigger. The electronic trigger subsequently acts on a relay which is located in the switch-on circuit of the shearer-loader and separates the shearer-loader from the electrical mains via the pilot protection and, as a result, prevents unacceptable increases in the winding temperature but also prevents overloading of individual motors. The drawbacks of the hitherto known prior art, as referred above, is that the system switches off the power supply connected to the shearer-loader in case of overloading of shearer-loader which causes frequent stopping of shearer-loader operation and increases the down time hours of the costly machine. This in turn reduces the production and productivity of the mine. Moreover, the system is equipped with a plurality of DC drive motors, which has an inherent difficulty for use in hazardous underground coal mines. In practice there is a definite need for improvement, particularly of the control operation of shearer-loader loading in underground long-wall coal mining to enable increase in productivity of shearer-loaders in particular and long-wall mining equipment in general. The main object of the present invention is to provide an autonomous control system for shearer-loader in underground long-wall coal mines which obviates the drawbacks of the hitherto known prior art as detailed above. Another object of the present invention is to provide a microprocessor based autonomous control system for shearer-loader in underground long-wall coal mines which obviates the drawbacks as detailed above. Yet another object of the present invention is to provide a microprocessor based automatic control of load on the cutter motor while it is cutting coal face by controlling the haulage speed of the shearer-loader. Still another object of the present invention is to provide a real-time controlling of torque fluctuation experienced by the shearer-loader motor during its operations in the coalface primarily due to variations in seam strength parameters, rock intrusions and faults encountered in coal seams, and overcoming the problem of frequent stopping of the shearer-loader while it is overloaded. Still yet another object of the present invention is to provide mechanism for reduction in rapid deterioration of winding insulation and premature failures, minimization of excessive vibrations and enhancement of life of machine components. A further object of the present invention is to provide an on-line controlling system for smooth acceleration/deceleration of the shearer-loader motors with the adjustable presets to suit a particular geo-mining condition. A still further object of the present invention is to provide a controlling system for decreasing down time hours of shearer-loader, and increasing the production and productivity of the mine. The microprocessor based autonomous control system of the present invention will be particularly useful for shearer-loader in underground longwall underground coal mines. The microprocessor based autonomous control system of the present invention for shearer-loader in underground longwall coal mines essentially consists of a cutting drum driven by cutting motor. Current and voltage sensor/transducer are connected to the cutter motor and output of which are sent to the analog to digital converter (ADC) unit of the microprocessor based controller. The speed of haulage motor is controlled by a variable speed drive and firing/timing circuit. The current transducer senses the current drawn by haulage motor, the tacho sensor senses the revolution per minute (RPM) of the haulage motor, the frequency sensor senses the output frequency of AC variable speed drive and the voltage transducer senses the output voltage of the variable speed drive. The output of all the sensors are connected to the analog to digital converter (ADC) unit of the microprocessor control unit having a display unit. A digital to analog converter (DAC) unit is connected to control the firing/timing circuit of the variable speed drive in order to control the speed of the haulage motor which is attached with the load. The system of the present invention is capable of automatic control of load on the cutter motor while it is cutting coal face by controlling the haulage speed of the shearer-loader. The system of the present invention enables controlling of torque fluctuation experienced by the shearer-loader motor during its operations in the coalface primarily due to variations in seam strength parameters, rock intrusions and faults encountered in coal seams, and overcoming the problem of frequent stopping of the shearer-loader while it is overloaded. The system also provides smooth control of acceleration/deceleration of the shearer-loader motors with the adjustable presets to suit a particular geo-mining condition. The autonomous control system for shearer-loader in underground long-wall coal mines, of the present invention is shown figure 1 of the drawing accompanying this specification. Figure 1 shows the block diagram (1) to (18) of the complete autonomous control system for shearer-loader of the present invention. The details of the block diagram (1) to (18) as depicted in figure 1 of the drawing are given below: The block diagram as depicted in figure 1 of the microprocessor based autonomous control system of the present invention for shearer-loader in underground longwall coal mines consists of: cutting drum (1) driven by cutting motor (2) which is connected to the underground high voltage AC power supply (3). The current sensor (4) and voltage transducer (5) are connected to the cutter motor and output of which are sent to the analog to digital converter (ADC) unit (6) of the microprocessor based controller (7). The speed of haulage motor (8) is controlled by the variable speed drive (9) and firing/timing circuit (10), these are connected to the AC power supply (3). The current transducer (11) senses the current drawn by haulage motor (8), the tacho sensor (12) senses the revolution per minute (RPM) of the haulage motor (8), the frequency sensor (13) senses the output frequency of AC variable speed drive (9) and the voltage transducer (14) senses the output voltage of the variable speed drive (9). The output of all the sensors (4, 5, 11-14) are connected to the analog to digital converter (ADC) unit (6) of the microprocessor control unit (7) which is attached with the display unit (15), digital to analog converter (DAC) unit (16) and regulated DC voltage (5 V) supply (17) which in turn gets power from main supply (3). The digital to analog converter (DAC) unit (16) is connected to control the firing/timing circuit (10) of the variable speed drive (9) in order to control the speed of the haulage motor (8) which is attached with the load (18). Accordingly the present invention provides an autonomous control system for shearer-loader in underground longwall coal mines, which comprises in combination a cutting drum (1) driven by a cutter motor (2), charactersied in that the said cutter motor (2) being connected to a current sensor (4) and voltage transducer (5); the said sensors (4, 5) being connected to an analog to digital converter (ADC) unit (6) of a microprocessor based controller (7), the said ADC unit (6) also being connected to a haulage motor (8), variable speed drive (9) and firing/timing circuit (10) through a plurality of sensors/transducers such as current transducer (11), tacho sensor (12), frequency sensor (13) and voltage transducer (14); output of all the said sensors/transducers (4, 5,11-14) being connected to the said ADC unit (6), the said microprocessor (7) being connected to a display unit (15), digital to analog converter (DAC) unit (16) and regulated DC voltage supply (17); the said DAC unit being connected to the firing/timing circuit (10); the said cutter motor (2), regulated DC voltage supply (17), variable speed drive (9) being powered by AC main power supply (3); the said haulage motor (8) being connected to load (18). In an embodiment of the present invention, the motors are provided with adjustable presets enabling smooth control of acceleration/deceleration of the shearer-loader. In another embodiment of the present invention, the output of all the sensors (4, 5, 11-14) are amplified to transistor to transistor logic (TTL) level and fed to the ADC unit (6) of the microprocessor control unit (7). In still another embodiment of the present invention, the microprocessor control unit (7) is provided with a software, in assembly language, which generates appropriate signal through the digital to analog converter (DAC) unit (16) of the microprocessor unit (7) to control the firing/timing circuit (10) of the variable speed drive (9) depending upon the values of incoming signals in order to control the speed of the haulage motor (8). In yet another embodiment of the present invention, the different units of the system are as follows: (a) Microprocessor control unit (7): chip - Intel 8085; EPROM - 32 KB; RAM - 32KB; (b) ADC unit (6):- input voltage - ± 5 V, resolution - 12 bits, operation - bipolar, conversion time - 33 mili-seconds, ADC type - dual slope integrating; (c) DAC unit (16):- output voltage - 5 V, resolution - 12 bits, operation - unipolar or bipolar, settling time -1 micro-second. (d) Variable speed drive (9): base - dedicated VLSI circuit, power system -consists of 3 phase rectifier and filter, transistorized/GTO inverter, and protections and diagnostics, Output - sine weighted double edge pulse width modulated pulses and after amplification, control the inverter over devices to give variable speed control, rectifier section - 3 phase full wave diode bridge with necessary surge suppression networks and capacitor filters for smoothing the bus, inverter section - fuse less electronic instantaneous trip over current protection at 160% of rated current, LED indicator for faults on control card for easy checking, frequency range - constant torque 0-50 Hz and constant HP 50-100 Hz, and acceleration/deceleration - 60-300 second adjustable. In still yet another embodiment of the present invention, the system incorporates real-time control of torque fluctuation experienced by the shearer-loader motor during its operations in the coalface. In a further embodiment of the present invention, the system provides soft start of the haulage motor ensuring gradual increase in cutting load to the main motor. In a still further embodiment of the present invention, the microprocessor control unit (7) is powered through regulated a 5 V DC voltage supply (17) which in turn gets power from the AC main power supply (3). In another embodiment of the present invention, the system incorporates manual start by an operator in the local/ remote mode by push button in case of failure of the microprocessor unit. In yet another embodiment of the present invention, the system incorporates means of stopping the haulage motor by a single push button, both in the manual or auto mode. In still yet embodiment of the present invention, the system incorporates various protections measures, such as, under / over voltage protection, over current protection, high temperature tripping facility, discharge of energy storage devices and earth leakage protection. In the present invention of a microprocessor based autonomous control system for shearer-loader in underground long-wall coal mines consists of a cutting drum (1) driven by cutting motor (2) which is connected to the underground high voltage AC power supply (3). The current sensor (4) and voltage transducer (5) sense the cutter motor current and voltage, respectively and output of which are sent to the analog to digital converter (ADC) unit (6) of the microprocessor based controller (7). The speed of haulage motor (8) is controlled by the variable speed drive (9) and firing/timing circuit (10), these are connected to the line supply (3). The current transducer (11) senses the current drawn by haulage motor (8), the tacho sensor (12) senses the rotation per minute (rpm) of the haulage motor (8), the frequency sensor (13) senses the output frequency of AC variable speed drive (9) and the voltage transducer (14) senses the output voltage of the variable speed drive (9) which is input to the haulage motor (8). The output of all the sensors (4, 5, 11-14) are suitably amplified to transistor to transistor logic (TTL) level and fed to the ADC unit (6) of the microprocessor control unit (7), and display unit (15) indicates the signals received by all the sensors (4, 5, 11-14). Subsequently, after processing the signals, the developed software generates appropriate signal through the digital to analog converter (DAC) unit (16) of the microprocessor unit (7) to control the firing/timing circuit (10) of the variable speed drive (9) depending upon the values of incoming signals in order to control the speed of the haulage motor (8). The microprocessor control unit (7) is powered (5 V DC) through regulated DC voltage supply (17) which in turn gets power from main supply (3). When the load of the cutting motor (2) increases, the haulage speed is reduced and vice versa, and this is indicated by the load (18) of the haulage motor (8). This ensures uniform loading of the cutting motor (2) and it is not unduly overloaded because of the random cutting resistance of the coal seam. In a physical embodiment of the monitoring system of the present invention the specifications of the different units of the system are as follows: Microprocessor control unit (7): chip - Intel 8085, EPROM - 32 KB, RAM - 32 KB; ADC unit (6):- input voltage - ± 5 V, resolution - 12 bits, operation - bipolar, conversion time - 33 mili-seconds, ADC type - dual slope integrating; and DAC unit (16):- output voltage - 5 V, resolution - 12 bits, operation - unipolar or bipolar, settling time - 1 micro-second. Variable speed drive (9): base - dedicated VLSI circuit, power system - consists of 3 phase rectifier and filter, transistorized/GTO inverter, and protections and diagnostics, Output - sine weighted double edge pulse width modulated pulses and after amplification, control the inverter over devices to give variable speed control, rectifier section - 3 phase full wave diode bridge with necessary surge suppression networks and capacitor filters for smoothing the bus, inverter section - fuse less electronic instantaneous trip over current protection at 160% of rated current, LED indicator for faults on control card for easy checking, frequency range - constant torque 0-50 Hz and constant HP 50-100 Hz, and acceleration/deceleration - 60-300 second adjustable. The novel features of the present invention have been realized by the non-obvious inventive steps of integrating the various sub-systems and components to function in combination as a microprocessor based autonomous control system for shearer-loader in underground longwall coal mines. The novelty and inventive steps of the present invention with respect to the hitherto known prior art are: (i) provision of automatic control of load on the cutter motor while it is cutting coal face by controlling the haulage speed of the shearer-loader, without stopping the shearer-loader while it is in operation; (ii) capable of on-line controlling of torque fluctuation experienced by the shearer-loader motor during its operations in the coal face primarily due to variations in seam strength parameters, rock intrusions and faults encountered in coal seams, and overcoming the problem of frequent stopping of the shearer-loader while it is overloaded; (iii) development of microprocessor based software for smooth controlling of acceleration/deceleration of the shearer-loader motors with the adjustable presets to suit a particular geo-mining condition; (iv) capable of reducing the rapid deterioration of winding insulation and premature failures, minimization of excessive vibrations and enhancement of life of machine components; and (v) capable of decreasing the down time hours of shearer-loader, and increasing the production and productivity of the mine. The control system of the present invention should be installed in the control panel of a shearer-loader for smooth operation in an underground longwall coal mines. The microprocessor based software has been developed taking into consideration the different operations of the shearer-loader, so that in each of its operating modes, the cutting motor is not overloaded and loading is controlled automatically. The different operating modes of the shearer-loader are: (i) sumping operation - during the sumping operation, the haulage motor is in manual mode and this operation is controlled by the operator with the help of potentiometer; (ii) fleeting operation - during the fleeting operation, the shearer-loader is moved up and down the face without cutting and this operation is controlled both by the manual mode and auto mode; in the manual local mode the operator sets the speed of the haulage motor at a required speed level on the control panel; similarly in remote mode the operator sets the speed of the haulage motor remotely by a hand held control panel connected by cable and a maximum speed for fleeting operation is set; in the auto mode, the microprocessor controls the haulage speed; the microprocessor ensures that the speed of the haulage motor does not increase the set speed; moreover, while travelling down the face any obstruction on path is faced, then the fleeting current of the haulage motor is sensed and the fleeting speed is decreased and stopped in case of larger obstruction; and, (iii) cutting operation - this cutting operation is controlled both by the manual mode and auto mode; in the local/ remote mode the cutting operation is controlled by the operator manually and the speed of the haulage motor is set by the operator on the potentiometer; while on operation, the haulage speed is regulated by the operator following visual inspection of the machine vibration level and/ or from experience of the operator so as not to overload the cutting motor. In the auto mode the microprocessor takes the place of the operator. It invokes the analog voltage signal continuously corresponding to the current drawn by the main cutting motor through a current transformer and signal conditioner. The microprocessor is suitably controlled the speed of the haulage motor by the speed control algorithm. Moreover, a maximum and minimum speed is set for the haulage motor by software. The software is developed in assembly language in modular form. All the basic functions to be performed by the microprocessor are developed in the form of subroutines and finally integrated for the development of the control software for above-mentioned three operating modes of the shearer-loader. The microprocessor based autonomous control system of the present invention will be particularly useful for shearer-loader in underground long-wall coal mines. The system of the present invention is capable of automatic control of load on the cutter motor while it is cutting coalface by controlling the haulage speed of the shearer-loader. The system enables controlling of torque fluctuation experienced by the shearer-loader motor during its operations in the coalface primarily due to variations in seam strength parameters, rock intrusions and faults encountered in coal seams, and overcoming the problem of frequent stopping of the shearer-loader while it is overloaded. The system provides smooth control of acceleration/deceleration of the shearer-loader motors with the adjustable presets to suit a particular geo-mining condition. The system reduces rapid deterioration of winding insulation and premature failures, minimizes excessive vibrations and enhances the life of machine components. The system decreases the down time hours of shearer-loader, and increases the production and productivity of the mine. The system facilitates soft start of the haulage motor to ensure gradual increase in cutting load to the cutter motor. The system also incorporates manual start by the operator in the local/ remote mode by push button in case of failure of the microprocessor unit. The system generates intrinsically safe control signal from the microprocessor to the drive which enhances the safety of the system being used in underground mines. The system includes various protection measures, such as, under / over voltage protection, over current protection, high temperature tripping facility and earth leakage protection. The following examples are given by way of illustration of the microprocessor based autonomous control system of the present invention for shearer-loader in underground long-wall coal mines and therefore should not be construed to limit the scope of the present invention. Example-1 The control system of the present invention was experimented in the laboratory with the simulated field conditions to analyze the variation of analog output voltage of tacho sensor (12) with the haulage motor (8) speed. The tacho sensor (12) attached with the haulage motor (8) developed a voltage in the range of 0 - 70 V in the whole speed range of the haulage motor (8). The circuit designed to make the tacho sensor (12) output voltage compatible to the ADC unit (6) of the microprocessor control unit (7) reduced and filtered to the range of 0 - 5 V. A series of experiments were conducted to linearise the dependence between the speed of haulage motor (8) and the analog voltage generated by the tacho sensor (12). It was observed that the best fit linear curve between these two obeyed the following relation: VT = 0.00317 n - 0.196 and the correlation coefficient (R2) was 0.97; where VT is the tacho voltage and n is the revolution per minute (rpm) of the haulage motor. This indicated that the system was successfully operated and controlled the haulage motor (8) speed in the simulated laboratory conditions. Example-2 The control system of the present invention was second time experimented in the laboratory with the simulated field conditions to analyze the variation of ADC unit (6) output to the microprocessor control unit (7) with the haulage motor (8) speed. The tacho sensor (12) output was fed to the input of the ADC unit (6) of the microprocessor control unit (7) and a programme was developed to digitize, read to the memory and display the corresponding digital value, Vd. It was observed that the digital value varies nearly linearly with the speed of the haulage motor (8) and the best fit curve obeyed the relation: Vd = 0.17 n - 14.29 and the correlation coefficient (R2) was 0.95. This experiment highlighted the successful operation of the microprocessor control unit (7) which successfully controlled the haulage motor (8) speed. Example-3 The control system of the present invention was third time experimented in the laboratory with the simulated field conditions to study the effectiveness of generated control signal by the microprocessor control unit (7) on haulage motor (8) speed variation. An assembly language programme was developed to process the signal received from the tacho sensor (12) and the random number generated by the microprocessor control unit (7) to produce a corresponding signal to control the variable speed drive (9). Following dependence relations were studied: (a) The digital control signal from the microprocessor control unit (7) was fed to the DAC unit (16) of the system. The resultant analog output raged from - 10 V DC to + 10 V DC. Only the positive portion of the microprocessor analog output was required to control the variable speed drive (9). A suitable subroutine was developed in the main programme which monitored the digital control signal and the positive analog voltage was applied to the variable speed drive (9). The variation of the analog output of the DAC unit (16) fed to the variable speed drive (9) with the digital control signal generated to the microprocessor control unit (7) was found to follow the relation: Vcon = 0.075 CN - 9.86 and the correlation coefficient (R2) was 0.99; where Vcon is the DC control signal fed to the drive and CN is the digital control signal generated by the microprocessor control unit (7). (b) The variation of analog voltage (VT) generated by the tacho sensor (12) with the change in the digital control signal from the microprocessor was found to suit the relation: VT = 0.038 CN - 5.542 and the correlation coefficient (R2) was 0.96. (c) The rpm of the haulage motor (8) was measured with the help of hand held tachometer. The variation of the speed (rpm) of the haulage motor (8) with respect to the digital control signal generated by the microprocessor control unit (7) was found to follow the relation: n = 12.05 CN- 1686.64 and the correlation coefficient (R2) was 0.98. The variation of coal seam strength as simulated in the laboratory and the variation of signal received by the current sensors were within the reasonable limits resulting from autonomous change in the speed (rpm) of the haulage motor. Other parameters were also observed as per the relation mentioned in the previous examples. These indicated that all major components of the system operated successfully for different simulated field conditions. The total control system of the present invention essentially enabled automatic control of load on the cutter motor while it is in operation. The system enabled control of torque fluctuation experienced by the shearer-loader motor during its operations and overcame the problem of stopping of the shearer-loader while it is overloaded. The system provided smooth control of acceleration/ deceleration of the shearer-loader motors with the adjustable presets. The microprocessor based software, developed in assembly language facilitated soft start of the haulage motor to ensure gradual increase in cutting load to the cutter motor and the acceleration of the haulage motor during starting. The system incorporated manual start by the operator in the local/ remote mode by push button in case of failure of the microprocessor unit. The system accomplished stopping of the haulage motor by a single push button, whether it was in the manual or auto mode. The system incorporated various protections measures, such as, under/over voltage protection, over current protection, high temperature tripping facility and earth leakage protection. Therefore, it is conclusively shown that the novel features realized by the non-obvious inventive steps enabled by microprocessor based autonomous control system for shearer-loader in underground longwall coal mines of the present invention essentially proved useful for effective automatic control of shearer-loader. The main advantages of the autonomous control system for shearer-loader in underground longwall coal mines, of the present invention are: 1. The system is capable of automatic control of load on the cutter motor while it is cutting coal face by controlling the haulage speed of the shearer-loader. 2. The system enables controlling of torque fluctuation experienced by the shearer-loader motor during its operations in the coalface primarily due to variations in seam strength parameters, rock intrusions and faults encountered in coal seams, and overcoming the problem of frequent stopping of the shearer-loader while it is overloaded. 3. The system provides smooth control of acceleration/deceleration of the shearer-loader motors with the adjustable presets to suit a particular geo-mining condition. 4. The system reduces rapid deterioration of winding insulation and premature failures, minimizes excessive vibrations and enhances the life of machine components. 5. The system decreases the down time hours of shearer-loader, and increasing the production and productivity of the mine. 6. The system facilitates soft start of the haulage motor to ensure gradual increase in cutting load to the main motor. During fleeting operation also the soft start facility is available. Moreover, the acceleration of the haulage motor during starting is software controlled. 7. The system incorporates manual start by the operator in the local/ remote mode by push button in case of failure of the microprocessor unit. 8. The system accomplishes stopping of the haulage motor by a single push button, whether it is in the manual or auto mode. 9. The system generates intrinsically safe control signal from the microprocessor to the drive which enhances the safety of the system being used in underground mines. 10. The system improves the overall reliability level by utilizing the electronic and power semiconductor components which have high reliability. 11. The system includes various protections measures, such as, under/ over voltage protection, over current protection, high temperature tripping facility, discharge of energy storage devices will be available and earth leakage protection. We claim: 1. An autonomous control system for shearer-loader in underground longwall coal mines, which comprises in combination a cutting drum (1) driven by a cutter motor (2), charactersied in that the said cutter motor (2) being connected to a current sensor (4) and voltage transducer (5); the said sensors (4, 5) being connected to an analog to digital converter (ADC) unit (6) of a microprocessor based controller (7), the said ADC unit (6) also being connected to a haulage motor (8), variable speed drive (9) and firing/timing circuit (10) through a plurality of sensors/transducers such as current transducer (11), tacho sensor (12), frequency sensor (13) and voltage transducer (14); output of all the said sensors/transducers (4, 5,11-14) being connected to the said ADC unit (6), the said microprocessor (7) being connected to a display unit (15), digital to analog converter (DAC) unit (16) and regulated DC voltage supply (17); the said DAC unit being connected to the firing/timing circuit (10); the said cutter motor (2), regulated DC voltage supply (17), variable speed drive (9) being powered by AC main power supply (3); the said haulage motor (8) being connected to load (18). 2. An autonomous control system for shearer-loader as claimed in claim 1, wherein the output of all the sensors (4, 5, 11-14) are amplified by transistor transistor logic (TTL) and fed to the ADC unit (6) . 3. An autonomous control system for shearer-loader as claimed in claim 1-2, wherein the microprocessor control unit (7) is provided with a software, in assembly language, which generates appropriate signal through the digital to analog converter (DAC) unit (16) to control the firing/timing circuit (10) of the variable speed drive (9) depending upon the values of incoming signals in order to control the speed of the haulage motor (8). 4. An autonomous control system for shearer-loader as claimed in claim 1-3, wherein the different units of the system are as follows: (a) Microprocessor control unit (7): chip - Intel 8085; EPROM - 32 KB; RAM - 32 KB; (b) ADC unit (6):- input voltage - ± 5 V, resolution - 12 bits, operation - bipolar, conversion time - 33 mili-seconds, ADC type - dual slope integrating; (c) DAC unit (16):- output voltage - 5 V, resolution - 12 bits, operation - unipolar or bipolar, settling time - 1 micro-second. (d) Variable speed drive (9): base - dedicated VLSI circuit, power system -consists of 3 phase rectifier and filter, transistorized/GTO inverter, and protections and diagnostics, Output - sine weighted double edge pulse width modulated pulses and after amplification, control the inverter over devices to give variable speed control, rectifier section - 3 phase full wave diode bridge with necessary surge suppression networks and capacitor filters for smoothing the bus, inverter section - fuse less electronic instantaneous trip over current protection at 160% of rated current, LED indicator for faults on control card for easy checking, frequency range - constant torque 0-50 Hz and constant HP 50-100 Hz, and acceleration/deceleration - 60-300 second adjustable. 5. An autonomous control system for shearer-loader as claimed in claim 1-4, wherein the system incorporates real-time control of torque fluctuation experienced by the shearer-loader motor during its operations in the coalface. 6. An autonomous control system for shearer-loader as claimed in claim 1-5, wherein the system provides soft start of the haulage motor ensuring gradual increase in cutting load to the main motor. 7. An autonomous control system for shearer-loader as claimed in claim 1-6, wherein the microprocessor control unit (7) is powered through regulated 5 V DC voltage supply (17). 8. An autonomous control system for shearer-loader as claimed in claim 1-7, wherein the system incorporates means of stopping the haulage motor by a single push button, both in the manual or auto mode. 9. An autonomous control system for shearer-loader as claimed in claim 1-8, wherein the system incorporates various protections measures, such as, under / over voltage protection, over current protection, high temperature tripping protection, discharge of energy storage devices and earth leakage protection. 10. An autonomous control system for shearer-loader in underground longwall coal mines, substantially as herein described with reference to the examples and drawing accompanying this specification.

Documents:

1025-DEL-2004-Abstract-(26-05-2011).pdf

1025-del-2004-abstract.pdf

1025-DEL-2004-Claims-(22-09-2011).pdf

1025-del-2004-claims.pdf

1025-DEL-2004-Correspondence Others-(22-09-2011).pdf

1025-DEL-2004-Correspondence Others-(26-05-2011).pdf

1025-del-2004-correspondence-others.pdf

1025-DEL-2004-Description (Complete)-(22-09-2011).pdf

1025-del-2004-description (complete).pdf

1025-del-2004-drawings.pdf

1025-DEL-2004-Form-1-(22-09-2011).pdf

1025-DEL-2004-Form-1-(26-05-2011).pdf

1025-del-2004-form-18.pdf

1025-del-2004-form-2.pdf

1025-DEL-2004-Form-3-(26-05-2011).pdf

1025-del-2004-form-3.pdf

1025-del-2004-form-5.pdf