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BACKGROUND  
       [0001]     The present invention, in general, relates to roll-up doors. More specifically, it relates to methods and systems for operating and securing roll-up doors.  
         [0002]     Roll-up doors are often installed in a garage, on the rear or sides of containers, such as tractor trailer payloads, commercial vans, shipping containers, and cargo containers. A roll-up door includes a flexible sheet, a mechanism to move the flexible sheet up and down, a locking mechanism, and a track to guide the movement of the flexible sheet.  
         [0003]     Conventionally, the roll-up doors are operated using a mechanism that requires manual effort to move the flexible sheet up or down. An operator lifts up the flexible sheet to open the roll-up door and pulls down the flexible sheet to close the roll-up door. Sometimes, the operator may attempt to reduce the physical effort required to fully open the roll-up doors by only partially opening the doors. However, the roll-up door may slide down the track. Therefore, to maintain the roll-up door at a particular position in the track, the operator may jam or push objects into the track or at the bottom of the roll-up door. As a result, the track may get damaged. The operator may also be injured.  
         [0004]     Moreover, in conventional systems a mechanical lock, such as a padlock, swing-lock and the like is provided, in order to secure and lock roll-up doors. However, the application of the mechanical lock makes the roll-up doors vulnerable to theft or pilferage. Therefore, in order to reduce the vulnerability of the roll-up doors, some roll-up doors have been fitted with systems to open, close and lock the roll-up door. For example, U.S. Pat. No. 6,047,576 assigned to Lanigan, et al., provides a system for roll-up doors which is activated using an exterior key. Upon activation, an interior latch structure is mechanically moved between an unlocked and a locked position. According to U.S. patent publication number 2004/0155477 assigned to Lanigan, et al., a controller has been provided for a motorized interior latch structure. A set of sensors monitor the movement of latch between a locked or an unlocked position. However, the systems described above require the operator to physically maneuver the roll-up door into a position for closing the roll-up door. The operator must either physically operate a key to activate a latch, or signal a controller to operate a motorized latch. Therefore, the operator has to physically operate the roll-up door. Moreover, due to the physical contact, the operator remains prone to the risks of a physical injury.  
         [0005]     In order to avoid the physical operation of roll up doors, some roll-up doors are provided with systems that automate the closing and opening of the door. However, such systems do not allow the operator to partially close or open the roll-up door. Moreover, the locking mechanism still remains manual.  
         [0006]     In light of the above discussion, there exists a need for a system and a method, which permits an operator to selectively open, close, position and lock a roll-up door. Moreover, the system should involve automatic operation of the roll-up door and the locking mechanism.  
       SUMMARY  
       [0007]     An objective of the invention is to provide a system for automated operation of a roll-up door.  
         [0008]     Another objective of the invention is to provide a system for automated locking of a roll-up door.  
         [0009]     Yet another objective of the invention is to provide a system for secure operation of a roll-up door.  
         [0010]     Still another objective of the invention is to provide an economical, easy to install, and compact system for operating a roll-up door.  
         [0011]     Still another objective of the invention is to provide a system for operating a roll-up door by using a Radio Frequency (RF) transmitter.  
         [0012]     The present invention relates to a system for the automated positioning of a roll-up door. The system includes a guide-track assembly, a roll-up door that includes panels moving along the guide track assembly, a linkage mechanism connected to the roll-up door for guiding the roll-up door along the guide-track assembly, an automated driving mechanism connected to the linkage mechanism for controlling the movement of the roll-up door along the guide-track assembly, and a radio-controlled electrical circuit for activating the automated driving mechanism.  
         [0013]     Furthermore, the present invention relates to a method for operating a roll-up door system, with the roll-up door system comprising a radio transmitter, a radio-controlled electrical circuit, an automated driving mechanism, a roll-up door and a linkage mechanism. The automated driving mechanism comprises an electric motor, a clutch plate, a driving wheel, a lever-arm mechanism and a solenoid. The method includes receiving a signal at the radio-controlled electrical circuit from an RF transmitter and energizing the solenoid based on the signal by using the radio-controlled electrical circuit. Thereafter, the electric motor is controlled by the radio-controlled electrical circuit on receiving the signal. Further, the lever-arm mechanism is actuated by using the energized solenoid. The lever-arm mechanism in turn engages the clutch plate to the driving wheel and the driving wheel moves the linkage mechanism to move the roll-up door.  
         [0014]     The present invention also relates to a method for operating a roll-up door system, with the roll-up door system comprising a radio transmitter, a radio-controlled electrical circuit, an automated driving mechanism, a roll-up door and a linkage mechanism. The automated driving mechanism comprises an electric motor, a clutch plate, a driving wheel, and a solenoid. The method includes receiving a signal at the radio-controlled electrical circuit RF transmitter and de-energizing the solenoid based on the signal. Thereafter, the electric motor is stopped by using the radio-controlled electrical circuit on receiving the signal and actuating the lever-arm mechanism by using the counter-balancing spring. Further, the clutch-disengaging spring disengages the clutch plate from the driving wheel if the roll-up door is at an intermediate position between ends of the guide-track assembly. The engaged clutch plate and driving wheel keep the roll-up door locked if the roll-up door is at one of the ends of the guide-track assembly.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The invention will hereinafter be described in conjunction with the appended drawings provided to illustrate and not to limit the invention, wherein like designations denote like elements, and in which:  
         [0016]      FIG. 1  illustrates a view of an exemplary operational environment for various embodiments of the present invention;  
         [0017]      FIG. 2  illustrates an outside view of a roll-up door system, in an embodiment of the present invention;  
         [0018]      FIG. 3  illustrates an outside view of an automated driving mechanism, in an embodiment of the present invention;  
         [0019]      FIGS. 4   a  and  4   b  illustrate the disengagement and engagement of a clutch plate and a driving wheel in an automated driving mechanism, in accordance with an embodiment of the present invention  
         [0020]      FIG. 5  illustrates an outside view of a linkage mechanism, in accordance with an embodiment of the present invention; and  
         [0021]      FIG. 6  illustrates a radio-controlled electrical circuit, in accordance with an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]     Various embodiments of the present invention provide a method and system for an automated and secure operation of a roll-up door. The roll-up door is operated by using a Radio Frequency (RF) transmitter. The various applications of the method and system include cargo containers for vehicles, security shades, industrial shutters, and roll-up entries into buildings. The embodiments of the present invention also provide a method and system capable of locking the roll-up door, in order to provide security for the various applications.  
         [0023]      FIG. 1  illustrates a view of an exemplary operational environment  100  for various embodiments of the present invention. Environment  100  includes a container  110  and a roll-up door system  120 . Container  110  includes side walls  112   a  and  112   b , and a ceiling wall  114 . Roll-up door system  120  includes a guide-track assembly  122 , a roll-up door  124 , a linkage mechanism  126 , an automated driving mechanism  128  and a radio-controlled electrical circuit  130 . Guide-track assembly  122  is fixed on side walls  112   a  and  112   b . In various embodiments of the present invention, guide-track assembly  122  is welded, riveted, secured by means of screws to side walls  112   a  and  112   b , and so forth. Roll-up door  124  moves along guide-track assembly  122 . Roll-up door  124  moves along guide-track assembly  122  by using a slider-track assembly. The slider-track assembly includes a slider-link, guide-track assembly  122 , and roll-up door  124 . The slider-link includes a rectangular sliding section and a rod attached at the center of the rectangular sliding section. Moreover, the rod is attached to roll-up door  124 . The sliding section is enclosed in guide-track assembly  122 . Therefore, roll-up door  124  is secured to move along guide-track assembly  122 . In an embodiment of the present invention, roll-up door  124  moves along guide-track assembly  122  by using a roller-track arrangement. The roller-track arrangement includes a roller, guide-track assembly  122 , and roll-up door  124 . The roller includes a rod, a central core and a pair of wheels. The pair of wheels is connected to each other through the central core. The pair of wheels is free to rotate about the central core. The rod is attached to the central core and roll-up door  124 . The roller is enclosed in guide-track assembly  122 . Therefore, roll-up door  124  is secured to move along guide-track assembly  122 . Further, roll-up door  124  is connected to linkage mechanism  126 . In various embodiments of the present invention, linkage mechanism  126  is fixed at one end to ceiling wall  114  through welding, rivets, screws, and other such means. The other end of the linkage mechanism  126  is connected to automated driving mechanism  128 . Automated driving mechanism  128  is fixed to side wall  112   a . In an embodiment of the present invention, automated driving mechanism  128  is fixed to ceiling wall  114 . Automated driving mechanism  128  moves roll-up door  124  on the basis of inputs from radio-controlled electrical circuit  130 .  
         [0024]      FIG. 2  illustrates an outside view of roll-up door system  120 , in an embodiment of the present invention. Roll-up door system  120  includes guide-track assembly  122 , roll-up door  124 , linkage mechanism  126 , automated driving mechanism  128 , and radio controlled electrical circuit  130 . Roll-up door  124  includes panels  202  and hinges  204 . Linkage mechanism  126  includes a slider-arm linkage  206 . Hinges  204  connect panels  202  by using screws. Panel  202   a  is connected to slider-arm linkage  206 . Panel  202   a  moves along guide-track assembly  122  due to the action of slider-arm linkage  206 .  
         [0025]     Radio-controlled electrical circuit  130  activates automated driving mechanism  128 . Thereafter, automated driving mechanism  128  actuates linkage mechanism  126 , which moves slider-arm linkage  206 . Slider-arm linkage  206  guides panel  202   a  along guide-track assembly  122 . Panel  202   a  drags along panels  202   b ,  202   c , and  202   d , and hinges  204 . Therefore, panels  202  move toward ceiling wall  114  or away from ceiling wall  114 , based on the actuation of linkage mechanism  126  by automated driving mechanism  128 . Roll-up door  124  opens when panels  202  move toward ceiling wall  114 . Roll-up door closes when panels  202  move away from ceiling wall  114 .  
         [0026]      FIG. 3  illustrates an outside view of automated driving mechanism  128 , in an embodiment of the present invention. Automated driving mechanism  128  includes a motor housing  310 , electric motor  320 , a clutch plate  330 , a driving wheel  340 , a lever-arm mechanism  350 , a clutch-disengaging spring  370 , and a bearing plate  380 . Electric motor  320  includes a drive shaft  322  and a transmission box  324 . Clutch plate  330  includes a central groove  332 , and holes  334 . Holes  334  include a hole  334   a  and a hole  334   b . Driving wheel  340  includes a central hole  342 , a bearing  344 , and pins  346 . Pins  346  include a pin  346   a  and a pin  346   b . Lever-arm mechanism  350  includes a mounting plate  352 , a lever arm  354 , a solenoid  356 , a counter-balancing spring  358 , and a spacer ring  360 .  
         [0027]     In an embodiment of the present invention, automated driving mechanism  128  is fixed to side wall  112   a  by using a base plate. Motor housing  310  is secured on the base plate and the base plate is fixed to side wall  112   a . Electric motor  320  is secured in motor housing  310 . Transmission box  324  couples electric motor  320  to drive shaft  322 . Further, drive shaft  322  of electric motor  320  fits into central groove  332  of clutch plate  330 . Drive shaft  322  is a half shaft and central groove  332  is a semi-circular groove. As a result, free motion of clutch plate  330  on drive shaft  322  is restricted. In various embodiments of the present invention, central groove  332  is a hub and a square groove. Further, drive shaft  322  is a splined shaft, or a square shaft. However, clutch plate  330  is capable of sliding along drive shaft  322 . Holes  334  are located at radial locations on clutch plate  330 . Pins  346  are located at radial locations on driving wheel  340 . Holes  334  are aligned to pins  346  in driving wheel  340  so that holes  334  and pins  346  are capable of engaging if clutch plate  330  slides along drive shaft  322 . Bearing  344  is fitted into central hole  342  of driving wheel  340 . Driving wheel  340  is a pulley. In an embodiment of the invention, driving wheel  340  is a sprocket wheel. Further, drive shaft  322  is fitted into bearing  344 . Therefore, driving wheel  340  is free to rotate about drive shaft  322  due to bearing  344 . In an embodiment of the present invention, an end plate is fitted at the end of drive shaft  322 , to prevent driving wheel  340  from sliding along drive shaft  322 .  
         [0028]     Holes  334  are engaged to pins  346  by lever-arm mechanism  350 . Mounting plate  352  is secured to motor housing  310 . One end of lever arm  354  is pivoted to mounting plate  352  and the other end is in contact with bearing plate  380 . Solenoid  356  is fixed on mounting plate  352 . Counter-balancing spring  358  is connected to mounting plate  352  at one end, and lever arm  354  at the other end. Solenoid  356  and counter-balancing spring  358  control the position of lever arm  354  along drive shaft  322 . Spacer ring  360  is placed concentrically to drive shaft  322 . Spacer ring  360  supports the end of lever arm  354  in contact with bearing plate  380 .  
         [0029]     Lever arm  354  and counter-balancing spring  358  are connected to mounting plate  352  by using a nut-bolt arrangement. In an embodiment of the present invention, the bolt passes through a hole at the pivoted end of lever arm  354 . Counter-balancing spring  358  is placed concentrically to the axis of the bolt. Further, the bolt passes through another hole in mounting plate  352 . Thereafter, a nut is tightened at the end of the bolt in order to secure lever arm  354  and counter-balancing spring  358 , to mounting plate  352 .  
         [0030]     Clutch-disengaging spring  370  is placed concentrically on drive shaft  322  between clutch plate  330  and driving wheel  340 . Bearing plate  380  is placed concentrically on drive shaft  322 , and is positioned between lever arm  354  and clutch plate  330 .  
         [0031]     Radio-controlled electrical circuit  130  activates automated driving mechanism  128  by supplying a current through the power lines of electric motor  320 . Further, solenoid  356  is energized by radio-controlled electrical circuit  130 . In an embodiment of the present invention, electric motor  320  is a Direct Current (DC) motor. Electric motor  320  is capable of rotating drive shaft  322  bi-directionally along an axis  326 . Drive shaft  322  rotates when the voltage is supplied to the power lines of electric motor  320 .  
         [0032]     Solenoid  356  includes a ring, a coil wound on the ring and a magnetic core. The core moves relatively to the ring when a current is passed through the coil. Due to the movement of the core, lever arm  354  is pushed along drive shaft  322 . Subsequently, lever arm  354  slides clutch plate  330  along drive shaft  322 . Holes  334  in clutch plate  330  are engaged with pins  346  due to this sliding movement. The disengagement and engagement of clutch plate  330  with driving wheel  340  is illustrated in conjunction with  FIGS. 4   a  and  4   b . Subsequently, drive shaft  322  rotates clutch plate  330 . Therefore, driving wheel  340  rotates when voltage is supplied to electric motor  320  and solenoid  356  is energized.  
         [0033]     Further, the rotation of driving wheel  340  in one direction moves roll-up door  124  toward ceiling wall  114  and the rotation in another direction moves roll-up door  124  away from ceiling wall  114 . The movement toward ceiling wall  114  is referred to as opening roll-up door  124 , and movement away from ceiling wall  114  is referred to as closing roll-up door  124 .  
         [0034]     In an embodiment of the present invention, when electric motor  320  stops and solenoid  356  is de-energized, counter-balancing spring  358  retracts lever arm  354  toward spacer ring  360 .  
         [0035]     Clutch-disengaging spring  370  disengages holes  334  in clutch plate  330  and pins  346  of driving wheel  340 , based on a parameter such as the stiffness of clutch-disengaging spring  370 . The stiffness of clutch-disengaging spring  370  is so chosen that a compression force of clutch-disengaging spring  370  is greater than a force, ‘F 1 ’. Force ‘F 1 ’ is the force required to disengage holes  334  in clutch plate  330  from pins  346  of driving wheel  340  when roll-up door  124  is at a location between ends of guide-track assembly  122 . Further, the compression force is less than a force, ‘F 2 ’. Force ‘F 2 ’ is the force required to disengage holes  334  in clutch plate  330  and pins  346  of driving wheel  340  when roll-up door  124  is at the ends of guide-track assembly  122 . In an embodiment of the present invention, force ‘F 2 ’ is the force required to move driving wheel  340  to release a contact pressure between pins  346  and holes  334  when holes  334  are much larger than pins  346 .  
         [0036]     In an embodiment of the present invention, electric motor  320  prevents manual operation of roll-up door  124  when holes  334  in clutch plate  330  and pins  346  of driving wheel  340  are engaged. This can be achieved by using a worm gear set in transmission box  324 . At the ends of guide-track assembly  122 , holes  334  in clutch plate  330  are engaged with pins  346  of driving wheel  340 , and transmission-box  324  prevents the movement of roll-up door  124 . Therefore, roll-up door  124  is locked at the ends of guide-track assembly  122 . Further, at a location between ends of guide-track assembly  122 , holes  334  in clutch plate  330  and pins  346  of driving wheel  340  are disengaged. Therefore, driving wheel  340  is free to move and roll-up door  124  can be operated manually.  
         [0037]      FIGS. 4   a  and  4   b  illustrate the disengagement and engagement of clutch plate  330  and driving wheel  340  in automated driving mechanism  128 , in accordance with an embodiment of the present invention.  FIG. 4   a  illustrates an outside view of automated driving mechanism  128  where solenoid  356  is de-energized and no electric current flows across the coil in solenoid  356 . The core of solenoid  356  is so positioned that lever arm  354  rests on spacer  360 . Holes  334  in clutch plate  330  and pins  346  of driving wheel  340  are disengaged. Therefore, driving wheel  340  is free to rotate on drive shaft  322 .  
         [0038]      FIG. 4   b  illustrates an outside view of the automated driving mechanism  128  where the solenoid  356  is in the energized state, that is, current is flowing in the coil of solenoid  356 . Lever arm  354  is pushed by the core of solenoid  356 . Lever arm  354  in turn, pushes clutch plate  330  along drive shaft  322 . Subsequently, holes  334  in clutch plate  330  and pins  346  of driving wheel  340  are engaged, and electric motor  320  rotates driving wheel  340 .  
         [0039]      FIG. 5  illustrates an outside view of linkage mechanism  126 , in accordance with an embodiment of the present invention. Linkage mechanism  126  includes an idler wheel  502 , a power-transmission medium  504 , and a slider-arm linkage  206 . In various embodiments of the present invention, power-transmission medium  504  is a belt, a chain, or a cable. Further, power-transmission medium  504  includes rings attached to ends in order to connect to slider-arm linkage  206 .  
         [0040]     Idler wheel  502  is fixed to ceiling wall  114 . Power-transmission medium  504  passes over idler wheel  502  and driving wheel  340 . One end of slider-arm linkage  206  is connected to power-transmission medium  504  and the end moves along guide-track assembly  122 . Another end of slider-arm linkage  206  is connected to roll-up door  124 . In an embodiment of the present invention, slider-arm linkage  206  includes a slider  506 , a slider-pin  508  and a linkage  510 . Slider  506  moves along guide-track assembly  122 . Linkage  510  is connected to roll-up door  124 . Slider-pin  508  connects slider  506  to linkage  510 . In another embodiment of the present invention, slider-arm linkage  206  is a roller-linkage. The roller-linkage includes a roller, a roller pin, and a linkage  510 . The roller moves along guide-track assembly  122 . Linkage  510  is connected to roll-up door  124 . The roller-pin connects the roller to linkage  510 . Moreover, power-transmission medium  504  is connected to linkage  510  by using a nut-bolt arrangement. The bolt passes through the rings and a hole in linkage  510 . The nut is then fitted onto the bolt.  
         [0041]     Driving wheel  340  actuates power-transmission medium  504  of linkage mechanism  126 . Power-transmission medium  504  moves idler wheel  502 . Slider-arm linkage  206  moves along with power-transmission medium  504  along the guide-track assembly  122 . Roll-up door  124  is pulled by slider-arm linkage  206  when driving wheel  340  rotates in a direction such that roll-up door  124  moves toward ceiling wall  114 . Roll-up door  124  is pushed by slider-arm linkage  206  when driving wheel  340  rotates in another direction such that roll-up door  124  moves away from ceiling wall  114 . Therefore, closing roll-up door  124  involves the pushing of roll-up door  124  by slider-arm linkage  206 , and opening roll-up door  124  involves the pulling of roll-up door  124  by slider-arm linkage  206 .  
         [0042]      FIG. 6  illustrates radio-controlled electrical circuit  130 , in accordance with an embodiment of the present invention. Radio-controlled electrical circuit  130  includes a Radio Frequency (RF) receiver  602 , channel relays  604 , a polarity reversal module  606 , a current-switching module  608 , and a power-supply switch  610 . Channel relays  604  include channel relay  604   a  and  604   b . Polarity reversal module  606  includes relay  612   a  and  612   b . Current-switching module  608  includes a current sensor  614  and a set-point switch  616 . In an embodiment of the present invention, current sensor  614  is an electro-magnet. In various embodiments of the present invention, current sensor  614  is a current sensing microprocessor circuit, a current sensing electrical circuit consisting of transistors, resistors, and diodes and so forth.  
         [0043]     Radio-controlled electrical circuit  130  activates automated driving mechanism  128 . Channel relays  604  receive input from RF receiver  602 . Channel relay  604   a  includes a common contact point ‘COM’, a normally open contact point ‘NO’, and a normally closed contact point ‘NC’. Channel relay  604   b  has similar form and functionalities as channel relay  604   a . Channel relay  604   a  has ‘COM’ at 12 Volts (V) DC. In an embodiment of the present invention, channel relays  604  are normally open relays. Channel relays  604  are connected to relays  612  in polarity reversal module  606 . Relay  612   a  includes a coil, a common contact point ‘COM’, a normally open contact point ‘NO’, and a normally closed contact point ‘NC’. Relay  612   b  has similar form and functionalities as relay  612   a . In various embodiments of the present invention, relays  612  in polarity reversal module  606  are electro-mechanical relays, Solid State Relays (SSR), MOSFET H-bridges, and the like. Relays  612  have ‘NC’ at 0 V DC, ‘NO’ at 12 V DC, coils connected to ‘NO’ of channel relays. The ‘COM’ of relay  612   a  and relay  612   b  are connected to the power lines of electric motor  320  and solenoid  356 . Current sensor  614  in current-switching module  608  measures the current passing through the connection between electric motor  320  and ‘COM’ of relay  612   a . Further, current sensor  614  is connected to set-point switch  616 . Set-point switch  616  includes a common contact point ‘COM’, a normally open contact point ‘NO’, and a normally closed contact point ‘NC’. The ‘COM’ of set-point switch  616  is connected to 12 V DC. Set-point switch  616  is connected to power-supply switch  610 . Power-supply switch  610  includes a coil, a common contact point ‘COM’, a normally open contact point ‘NO’, and a normally closed contact point ‘NC’. Power-supply switch  610  has NC at 12 V DC. The coils of power-supply switch  610  are connected to the ‘NO’ of set-point switch  616 . Further, the ‘COM’ of power-supply switch  610  is connected to 12 V DC supplies of channel relays  604  and set-point switch  616 . In various embodiments of the present invention, the voltage supplies at the contact points, switches, and relays is 24 V DC, 36 V DC, and so forth.  
         [0044]     In an embodiment of the present invention, set-point switch  616  includes an electro-mechanical relay and a printed circuit board. Current sensor  614  is coupled to one of the power lines of electric motor  320 . This allows the circuit on the printed circuit board to detect the current passing through the power lines into electric motor  320 . The circuit on printed circuit board includes a potentiometer, which enables setting a set-point. When the current passing through the power lines of electric motor  320  exceeds the set-point, the printed circuit board energizes the coil of its electro-mechanical relay.  
         [0045]     In an embodiment of the present invention, protection diodes are connected to the coils in various relays and switches. The protection diodes protect transistors and chips from a spike in voltage, when the coil is de-energized. In another embodiment of the present invention, a capacitor is connected to the power-supply switch  610 , to increase the time for the coil of power-supply switch to get energized. The capacitor is also connected to set-point switch  616  for increasing the sensitivity of set-point switch  616 .  
         [0046]     Radio-controlled electrical circuit  130  is controlled by radio signals. In an embodiment of the present invention, the radio signals are transmitted by an RF transmitter. The RF transmitter includes two buttons—an up-button and a down-button. When the up-button and the down-button are pressed, a corresponding RF signal is transmitted to RF receiver  602 . The up-button opens roll-up door  124  and the down-button closes roll-up door  124 . In an embodiment of the present invention, the up-button is pressed at the RF transmitter when roll-up door  124  is stationary. An up-signal is transmitted by the RF transmitter. RF receiver  602  receives the up-signal and provides an input to channel relays  604 . Channel relay  604   a  changes the state, based on the input. The ‘NO’ of channel relay  604   a  closes and the voltage at the ‘NO’ of channel relay  604   a  changes from 0 V DC to 12 V DC. The coil of relay  612   b  gets energized. The ‘NO’ of relay  612   b  closes. The voltage at ‘COM’ of relay  612   b  changes from 0 V DC to 12 V DC. The ‘COM’ of relay  612   a  is at 0 V DC. Therefore, there is a voltage difference across the power lines of electric motor  320  and solenoid  356 . Electric motor  320  moves driving wheel  340  and simultaneously solenoid  356  engages holes  334  in clutch plate  330  and pins  346  of driving wheel  340 . In an embodiment of the present invention, in the above-mentioned configuration of power lines of electric motor  320 , driving wheel  340  rotates to move roll-up door  124  toward ceiling wall  114 .  
         [0047]     In an embodiment of the present invention, the up-button is pressed at the RF transmitter when roll-up door  124  is moving toward ceiling wall  114 . RF Receiver receives the up-signal and provides the input to channel relays  604 . Channel relay  604   a  changes the state, based on the input. The ‘NO’ of channel relay  604   a  is already closed and therefore, it opens and the voltage at the ‘NO’ of channel relay  604   a  changes from 12 V DC to 0 V DC. The coil of relay  612   b  gets de-energized. The ‘NO’ of relay  612   b  is already closed and therefore, it opens. The voltage at ‘COM’ of relay  612   b  changes from 12 V DC to 0 V DC. The ‘COM’ of relay  612   a  is at 0 V DC. Therefore, there is no voltage difference across the power lines of electric motor  320  and solenoid  356 . Electric motor  320  stops driving wheel  340  and simultaneously solenoid  356  is de-energized. Therefore, roll-up door  124  stops moving up.  
         [0048]     In an embodiment of the present invention, the down-button is pressed at the RF transmitter when roll-up door  124  is stationary. A down-signal is transmitted by RF transmitter. RF receiver  602  receives the down-signal and provides an input to channel relays  604 . Channel relay  604   b  changes the state based on the input. The ‘NO’ of channel relay  604   b  closes and the voltage at the ‘NO’ of channel relay  604   b  changes from 0 V DC to 12 V DC. The coil of relay  612   a  gets energized. The ‘NO’ of relay  612   a  closes. The voltage at ‘COM’ of relay  612   a  changes from 0 V DC to 12 V DC. The ‘COM’ of relay  612   b  is at 0 V DC. Therefore, there is a voltage difference across the power lines of electric motor  320  and solenoid  356 . Electric motor  320  moves driving wheel  340  and simultaneously solenoid  356  engages holes  334  in clutch plate  330  and pins  346  of driving wheel  340 . In an embodiment of the present invention, in the above-mentioned configuration of power lines of electric motor  320 , driving wheel  340  rotates to move roll-up door  124  away from ceiling wall  114 .  
         [0049]     In an embodiment of the present invention, the down-button is pressed at the RF transmitter when roll-up door  124  is moving away from ceiling wall  114 . RF Receiver  602  receives the down-signal and provides the input to channel relays  604 . Channel relay  604   b  changes the state, based on the input. The ‘NO’ of channel relay  604   b  is already closed and therefore, it opens and the voltage at the ‘NO’ of channel relay  604   b  changes from 12 V DC to 0 V DC. The coil of relay  612   a  gets de-energized. Consequently, the ‘NO’ of relay  612   a , which was closed, opens now. The voltage at ‘COM’ of relay  612   a  changes from 12 V DC to 0 V DC. The ‘COM’ of relay  612   b  is still at 0 V DC. Therefore, there is no voltage difference across the power lines of electric motor  320  and solenoid  356 . Electric motor  320  stops driving wheel  340  and simultaneously solenoid  356  is de-energized. Therefore, roll-up door  124  stops moving away from ceiling wall  114 .  
         [0050]     In an embodiment of the present invention, the RF transmitter includes three buttons—an up-button, a down-button, and a stop-button. When any of the up-button, the down-button, or the stop-button is pressed, a corresponding RF signal is transmitted to RF receiver  602 . The up-button opens roll-up door  124  and the down-button closes roll-up door  124 . The stop-button stops roll-up door  124  at a location between ends of guide-track assembly  122 .  
         [0051]     Current sensor  614  connected to set-point switch  616 , measures the current passing through electric motor  320 . Set-point switch  616  closes the ‘NO’ when the current in electric motor  320  crosses a predetermined set-point. In an embodiment of the present invention, the predetermined set-point is a fraction of the maximum amperage that electric motor  320  can handle. In various embodiments of the present invention, the predetermined set point is crossed when an obstacle is encountered in guide-track assembly  122 , an object prevents roll-up door  124  from moving, roll-up door  124  has reached the end locations of guide-track assembly  122 , in case of electrical malfunctions, and so forth. When the predetermined set-point is exceeded, the ‘NO’ of set-point switch  616  is closed. The voltage at the ‘NO’ of set-point switch  616  changes from 0 V DC to 12 V DC. Subsequently, the coil of power-supply switch  610  is energized. The ‘NO’ of power-supply switch  610  closes and the ‘NC’ of power-supply switch  610  opens. The voltage at the ‘COM’ of power-supply switch  610  changes from 12 V DC to 0 V DC. Supplies of channel relays  604  and set-point switch  616  also change to 0 V DC. The voltage difference across electric motor  320  and solenoid  356  is zero and therefore, electric motor  320  stops functioning. Henceforth, roll-up door  124  stops moving. As electric motor  320  stops, current sensor  614  no longer measures any current. Consequently, as the electric current is below the predetermined set-point, the ‘NO’ of set-point switch  616  opens. Subsequently, power is supplied to polarity-reversal module  606  and current-switching module  608 , and therefore, radio-controlled electrical circuit  130  is ready to control the movement of roll-up door  124 .  
         [0052]     Embodiments of the invention have the advantage of maneuvering the roll-up door to any desired position automatically. Further, the roll-up door can also be manually operated. In an embodiment of the present invention, the use of an RF transmitter to automatically control the roll-up door prevents probable injuries to the operator. Embodiments of the present invention provide automatic locking of the roll-up door at the end locations of the guide-track. Further, the embodiments provide a system that is compact, economical, easy to install, and easy to operate.  
         [0053]     While the preferred embodiments of the invention have been illustrated and described, it will be clear that the invention is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art without departing from the spirit and scope of the invention as described in the claims.

Summary:
A roll-up door system has been provided to position a roll-up door. The roll-up door system uses a combination of electrical and mechanical systems, to achieve automatic locking and automated maneuvering of the roll-up door. The roll-up door system includes a guide-track assembly, a roll-up door moving along the guide track assembly, a linkage mechanism connected to the roll-up door for guiding the roll-up door along the guide-track assembly, an automated driving mechanism connected to the linkage mechanism for controlling the movement of the roll-up door along the guide-track assembly, and a radio-controlled electrical circuit for activating the automated driving mechanism.