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This is a continuation, of prior application Ser. No. 10/368,134, filed Feb. 18, 2003 now U.S. Pat. No. 7,023,162, which is hereby incorporated herein by reference in its entirety. 

   BACKGROUND 
   The present invention relates to automatic barrier movement operators. 
   Barrier movement systems are known in the art and generally comprise a motor for moving the barrier in response to a controller which determines necessary actions by responding to barrier travel limits, safety apparatus and user command input signals. With such known systems the travel limit determining apparatus is maintained at the controller and represents the controller&#39;s view of the barrier. Should the barrier be disconnected from the controller and moved, the barrier position may become unknown leading to lack of ability to automatically control the barrier. 
   Similarly, known systems may respond to a number of safety input devices, such as edge contact sensors or optical obstruction detectors, which is limited by the number of input ports provided for such. This is particularly so in commercial door operators or gate operators where the eventual equipping of the system depends on an unpredictable environment and the needs of the users and installers of such devices. Such a problem is quite complex for gate operators where the number of combinations of optical detectors and edge detectors is large and depends on factors unknown at the time the system is manufactured. 
   Known systems include the ability to optionally respond to wireless communications. Such systems typically require separate decoders for each wireless transmitter or type of transmitter resulting in undue complexity and cost. Also known systems typically start and stop barrier movement with a linear increase and decrease of power applied to a driving motor. Such systems do not pay continuing attention to barrier position and may result in efficient barrier movement or a barrier which moves too slowly or even stops before a destination limit of travel. 
   SUMMARY  
   The above disadvantages are overcome in accordance with the barrier movement operator described and claimed herein. 
   In accordance with one embodiment apparatus for generating position signals is disposed remotely from a controller of the apparatus and periodically reports position signals to the controller. Advantageously, the position sensor may comprise circuitry for producing an analog representation of position and an analog to digital convertor for periodically reporting digital position signals to the controller. 
   An embodiment also includes the ability to operate with an expanded number of safety devices such as edge contact detectors and optical obstruction detectors. Advantageously, the two types of safety devices produce non-interfering normal and safety signals so that different types of safety devices can be connected to the same input terminal. Upon receipt of a safety alerting signal the controller determines which type of device generated the signal and then performs a safety action associated with the signaling type of device. 
   The described and claimed barrier movement system also may respond to wireless user commands. Advantageously, the controller includes a single decoder which learns wireless input commands directed toward different operator functions such as movement of one barrier, movement of another barrier and movement of both barriers. The wireless commands are learned in a manner which can be used to duplicate the appropriate action when subsequent receptions of the same wireless command occur during an operate mode of the device. The fact that a received wireless command matches a previously learned command is reported to the controller on a separate communication path associated with the functions to be performed. 
   An improved method of setting limits of barrier travel is also described and claimed herein. Upon initiation of a limit learn function a barrier is moved to an end limit and a command signal is sent to the controller which responds by storing the end limit. The barrier is then moved to the other end limit, the position of which is stored by the controller in response to another command signal. The command signals may be produced by user inter action with a command button of the controller or by wireless transmissions. 
   Power is reduced to the barrier moving motor when a predetermined position of travel is reached with regard to an end limit. Such reduction of power is achieved by reducing the applied power in a non-linear function based on the actual position of the barrier as it slows. The non-linear reduction of power may be achieved, for example, by reducing power by a predetermined amount identified by barrier position. Non-Linear reduction may also be achieved by calculating the amount of power needed to reduce applied power to a predetermined minimum power. When power is being reduced it is possible that the barrier will move too slowly or stop altogether. Advantageously, the speed of barrier movement can be determined from recent position signals and, when too slow, power can be increased to provide a minimum rate of barrier travel. 

   
     BRIEF DESCRIPTION OF DRAWING 
       FIG. 1  is a combined schematic of an automatic gate operator; 
       FIG. 2  is a cross-sectional view of a telescoping used to move the gates of  FIG. 1 ; 
       FIGS. 3 and 4  show portions of the telescoping arm in retracted position and extended position respectively; 
       FIG. 5  is a schematic diagram of a position sensor signal generator; 
       FIG. 6  is a combined block diagram and structural diagram of the safety equipment used in a gate operator; 
       FIG. 7  is a block diagram of a controller for the gate operator; 
       FIG. 8  is a schematic diagram of electrical connections to a set of input terminals; and 
       FIGS. 9 and 10  are representations of power applied to a motor to move the gate of the gate operator system. 
   

   DESCRIPTION  
     FIG. 1  represents a barrier movement operator embodied as a gate opening and closing system. Although the embodiments and examples are written in terms of an automatic gate operator, it is to be understood that the principles discussed herein are equally applicable to other barrier operators such as garage door operators, solid door movers and window or shutter controllers. The gate operator system includes a pair of gates  11  and  13  each of which is mounted to swing from a respective post  10  mounted on either side of a passageway  51  ( FIG. 6 ). A telescoping arm assembly  150  is connected between a post  10  and gate  11  and another telescoping arm assembly  150  is connected between the other post  10  and gate  13 . The gates are individually moved by extending and retracting a portion  20  of the arm  150 . The extension and retraction are controlled by signals from a control unit  15  which is in overall control of the barrier movement system. Control unit  15  responds to user commands to open and close the gates and also responds to feedback information from the telescoping arms  150  and information from photo eyes  17  and  18  and edge contact sensors  24  and  25 . 
   A more detailed representation of a telescoping arm is presented in  FIG. 2 . Telescoping arm  150  includes an electric motor  27  which rotates in response to electrical power provided from controller  15  via conduction path  29 . In the disclosed embodiment motor  27  is a DC motor responding to pulse width modulated power however, it is to be understood that other types of electrical motors may be used when their rotation speed and/or output power can be controlled. The power output of motor  27  is connected by a rotation coupling  36  to a drive end  32  of a screw shaft extension. Coupling  36  provides gear reduction from motor  27  and permits a user to decouple the motor from drive  32 . The make-up of coupling  36  is not described in detail herein. Drive end  32  is coupled by an extension  121  to rotate an elongated screw shaft  34 . 
   Telescoping arm  150  comprises an outer tube  40  having therein an inner extension tube  20 . A nut  102  having threads to mate with the threads of screw shaft  34  is disposed at an inner end of inner tube  20 . Accordingly, when drive  32  is rotated, screw shaft  34  rotates and inner tube  20  is extended or retracted from and into outer tube  40  depending on the direction of rotation. The pitch of screw threads on shaft  34  is such that on the order of 8 or 9 revolutions of shaft  34  will fully extend or fully retract the inner tube  20 . It should also be mentioned that when the motor  27  is decoupled from drive end  32 , the inner tube  20  can be extended and retracted by pulling and pushing thereon. Such manual extension and retraction causes a rotation of screw shaft  34  in the same amount as occurs from motor  27 , when coupled. 
   Extension shaft  121  is coupled by means of a driving belt  120  to a 10 turn potentiometer  38 . The relative diameters of shaft  121  and the control shaft of potentiometer  38  are such that a complete extension of inner tube  20  results in less than 10 rotations of the potentiometer shaft. Thus, the range of potentiometer is not exceeded during a full extension or retraction of the inner tube  20 . The wiper  42  of potentiometer is connected as an input to an analog to digital converter  44  which is disposed within telescoping arm  150  along with the potentiometer  38 . As shown in  FIG. 5  the fixed ends of the potentiometer resistance are respectively connected to a reference voltage and to ground so that as the shaft  34  rotates, either by the action of motor  27  or manual action, a variable voltage is applied to the analog to digital convertor  44 . In  FIG. 5  analog to digital converter is represented as a microprocessor  44  which both produces digital representations of the analog position voltage and serially transmits those digital representations from the telescoping arm  150  to the controller  15 . Microprocessor  44  is programmed to periodically transmit the digital position representing signals approximately every 50 m sec although other periods of transmission could be used. 
     FIG. 6  is a plan view of the barrier movement apparatus showing particularly the safety apparatus which may be associated with the gate. Posts  10  are disposed at either side of passageway  51 . The gates  11  and  13  are attached to posts  10  to swing in an orientation which opens and closes access along the passageway. A plurality of photo eye pairs are disposed to form a frame around the area over which the gates swing. The pair of photo eyes  17 – 18  surveys a line across the passageway next to posts  10  while a pair of photo eyes  47 – 48  surveys the passageway just beyond the ends of the open gates. Each side of the passageway may also be protected by a pair of photo eyes. Photo eyes  53 – 54  survey one side of the passageway just outside the travel of gate  11  and photo eyes  56 – 57  survey a similar site on the gate  13  side. The photo eyes are electrically connected in pairs for communications with controller  15 . An optical beam is normally transmitted from one photo eye e.g.,  47  to another of the pair e.g.,  48 . When the optical beam is properly received the photo eye pair returns a predetermined voltage with periodic drops to zero volts to the controller  15 . In an embodiment the drops to zero volts occur approximately every  7  m sec. When an obstruction breaks the optical beam the voltage remains at the predetermined voltage level without drops to zero volts and remains so until the obstruction is removed. Controller  15  is programmed to respond to a signal identifying an optically detected obstruction by stopping all movement of the gates until the obstruction is removed and proper signals are again received. 
   The edge contact obstruction sensors e.g.,  24  and  25  are also connected to provide safety signals to controller  15 . Edge sensors  24  and  25  are normally open contact switches the contacts of which have a predetermined edge sensor voltage applied between them. Normally the edge sensor voltage is detected by controller  15  indicating that no obstruction has been touched. Alternatively, when an obstruction is touched the normally open contacts are shorted and the voltage detected by the controller  15  drops to substantially zero and remains there until the edge sensor e.g.,  24  is no longer touching an obstruction. Some edge sensors also include a known resistance connected between the sensor contacts at one end of the edge sensor. This permits the controller  15  to check for a constant current for assurances of a working sensor, but a signal of zero volts is still the safety signal. Thus, an edge safety signal comprises a drop of voltage sensed by controller  15  to substantially zero volts. Controller  15  is programmed to respond to an edge sensor safety signal by reversing the travel of all moving gates for a fixed distance. 
   The safety signals from edge sensors e.g.,  24  and from photo eye pairs e.g.,  47 – 48  are all applied to a set of input terminals  59  which are shown in greater detail in  FIG. 8 . Each input terminal  61 – 64  can be connected to one or more safety devices of either optical (photo eye) or edge contact type. When both optical and contact type sensors are connected to a terminal, that terminal will exhibit a predetermined voltage with near zero drops at an approximately a 7 m sec period when neither device has an obstruction. That is, the near zero drops by the optical sensor will pull the contact sensor voltage to zero for the time of the drops. Should the contact sensor strike an obstruction the voltage on the line will be pulled to a constant near zero. If instead the optical sensor is blocked by an obstruction the terminal will remain high which will be detected because the near zero drops on the input were present, but have gone away. Controller  15  periodically scans the input terminals  61 – 64  to determine that no safety signals are present. When a safety signal is detected, controller  15  identifies whether it is an optical safety device or a contact safety device which is creating the signal and takes appropriate action. That is, when the detected safety signal is from an edge contact sensor the direction of movement is reversed and when an optical safety signal is detected, gate movement is not started or stopped if motion is occurring. The input terminals  61 – 64  can be shared because the optical safety signal is a constant predetermined voltage while the edge contact safety signal is a constant near zero volt signal. 
   During the set up of the gate operator the controller  15  is taught the end limits of travel of the gates. First, the user presses a limit learn button  66  ( FIG. 7 ) to which processor  68  of controller  15  responds by entering the limit learn mode. The user then uncouples the motor  27  from the extension screw  34 , if not already done, and manually moves a first gate to either the open or the closed position and signals such by pressing manual gate operator control button  70 . Then the user manually moves the gate to the other limit position and again presses the control button  70 . When, as shown in  FIGS. 1 and 6 , two gates are present the user repeats the process with the second gate. The controller  15  records in memory the digital representation of position from analog to digital controllers  44  at each open and closed limit for each gate. The gate can be controlled to move between the stored position limit values. It may be desirable for the controller to know which stored position limit corresponds to an open gate and a closed gate. In embodiments where such is desired the controller is programmed to expect the position limits for a predetermined state such as closed first. On the preceding limit setting process, limits were identified when a user pressed a control button  70 . When the barrier movement system is equipped with wireless command capability (discussed below), wireless commands can also be used to identify limits in the same manner as button  70 . 
   The barrier movement system of the present description may also include a wireless security code transmitter  72  which can wirelessly initiate movement of one or more of gates  11  and  13 . Transmitter  72  transmits gate commands by RF signals, however, other types of wireless signaling such as optical or acoustic could be used. Controller  15  includes an RF receiver  74  which receives transmission from transmitter  72  via an antenna  76 . Representations of received signals are sent to a decoder  78  which validates selected received signals and notifies processor  68  via one of a plurality of conductors of which conductor  81 ,  82  and  83 . Validation of a received RF transmission is done on the basis of transmitted security codes and before validation can occur, the decoder  78  is taught values which are later compared to received security codes to complete validation or not. 
   Decoder  78  includes a microprocessor and memory which are programmed to operate in a learn mode and in an operate mode. Although different numbers of such buttons could be provided, decoder  78  is connected to three learn buttons  85 ,  86  and  87 . In the present embodiment button  85  represents a learn mode for movement of gate  13 , button  86  represents a learn mode for gate  11  and button  87  represents a learn mode for both gates. 
   Transmitter  72  includes three transmit buttons  90 ,  91  and  92 , each of which is associated by transmitter  74  with a unique security code. When a transmit button e.g.,  90  is pressed an RF transmission is sent which includes the security code unique to the pressed button. When a user wants to train the controller  15  to validate and respond to a wireless security code, such a security code must be stored by the decoder  78 . When the user wants the security code to control gate  13 ,  11 , or both, a button  85 ,  86  or  87  respectively is pressed to enter the learn mode for the correct gate or combination. The user then presses the button on transmitter  72  which is to perform the desired control. Upon pressing the appropriate transmitter button e.g.,  90  the decoder  78 , via receiver  74 , receives a representation of the unique code associated with button  90  and stores it in a manner which identifies the gate or gates which are to respond to the newly stored code. After the received security code is stored in decoder  78 , the decoder switches from the learn mode to the operate mode. Subsequent receipts of the code from transmitter  72  button  90  will cause decoder to send a command to processor  68  via a selected one of conductors  81 ,  82  or  83 . The particular conductor  81 ,  82  or  83  selected, defines whether gate  11 ,  13  or both are to operate. Finally, when processor  68  receives a command on one of conductors  81 ,  82  or  83  the gate or gates associated with that conductor are controlled. 
   Processor  68  of controller  15  responds to input signals from decoder  78 , command button  70  and the safety input by starting, moving and stopping one or both gates. Such control is exercised by sending pulse width modulated DC to one or both of the motors  27  of telescoping arms  150 . A gate is started from a first limit (limit 1 ,  FIG. 9 ) by applying approximately 25% of full power which is ramped upward to achieve 100% power at a predetermined point of gate travel X 1 . The power level remains 100% until the gate achieves a second point X 2  at which the power is diminished until the 25% level is achieved at the destination end point. In the embodiment represented by  FIG. 9  the power is not linearly ramped down in the reverse of the up ramp of start up power. Instead the power is non-linearly reduced to achieve a safe and efficient slowing and stopping the gate. Such non-linearly power reduction is achieved by reducing the power based on gate position as reported by the position sensing potentiometer  38  and analog to digital converter  44 . 
   In a first embodiment after gate position X 2  is achieved the power may be reduced by a predetermined amount for each gate position reported from the telescoping arm  150 . Such reductions are pre-established to achieve the non-linear reduction in power represented in  FIG. 9 . Alternatively, power may be reduced by calculating, for each reported gate position, the amount of power estimated to achieve 25% by the destination limit 2 . In either case, the non-linear reduction is achieved by reducing power based on door position. 
   For reasons such as wear and tear on the gates as they age it is possible that the forces required to move the gate may be unpredictable. When the gate is speeding up or traveling at full power such required force will be overcome by the relatively high power levels. When power is being reduced it is possible that the unpredictable forces will cause the gate to move more slowly than desired or even stop.  FIG. 10  represents an embodiment employed to overcome the slow or stopped gate situation. As before the non-linear power reduction begins when a position X 2  is indicated for the gate. As in  FIG. 9  the power reduction is reduced based on gate position, however, the times and gate positions of recent reportings are also considered to estimate the speed at which the gate is moving. Such speed maybe, for example, determined from the last 5 position reports. When the speed falls below a predetermined amount given the current gate position, the power level is increased to achieve at least a predetermined rate. In one specific embodiment if the gate position is reported as the same (no movement) for the predetermined number of reports e.g., 5, the power is increased beginning at point  98  where no movement was detected. Such increase continues until the speed calculation indicates an adequate speed for safety and efficiency.

Summary:
A barrier movement operator is having a position sensor in a telescoping barrier control arm is described. A controller, remote from the arm, senses the barrier position to identify limits of barrier travel and to control rate of travel of the barrier between limits. The operator includes both optical and edge sensor obstruction detectors and is responsive to wireless communication for receiving user initiated command signals.