Abstract:
A method and system for controlling the speed of security gate depending on its length is disclosed. It includes a system for determining the length of a gate that the system is working with and which automatically sets the speed of movement of the gate based on length. The system works automatically so that human intervention is not necessary to set the optimal speed once installed.

Description:
FIELD OF THE INVENTION 
   The present invention relates to control of operation of movable security barriers and more particularly to optimizing the speed with which such barriers open and close. 
   BACKGROUND OF THE INVENTION 
   The speed with which a security gate can safely open and close is dependent on the length and mass of the gate. The safe speed is inversely proportional to the length and mass of the gate. A swinging gate eight feet in length and of moderate mass can safely open and close in eight seconds. However, a gate 16 feet in length can only safety open and close in 13 seconds or more. To attempt to force a gate to open or close at speed faster than the safe speed subjects it to stress and forces that could damage the gate or injure those in the vicinity of the gate. 
   One of the disadvantages of a movable security gate or barrier is that every time one has to pass through it they have to wait for it to open or close. Additionally, having to go through a security gate or barrier numerous times during a short time period such as during anyone day can be tedious and frustrating since one has to stop and wait for the gate to open or close. Attempts to speed up movement of the gate can result in a dangerous situation if the gate is moving too fast. As noted above excessive speed of movement of the gate can put stress on the gate and cause it to malfunction or break. Also, excessive speed of movement for a gate can create dangerous situations that can cause injury to those in the vicinity of the gate or passing through the opening the gate covers. 
   In the past to avoid a security gate installation that had a gate that might be operating at an excessive speed security gate manufactures often produced gate controllers that limited the speed a gate attached to the controller to the Lowest common denominator. The lowest common denominator being the speed a gate 16 feet in Length might be able to open at. If the controller was installed with a gate 16 feet in length it was operating the gate at its maximum safe speed. However, if the controller was installed at a location with an eight feet the gate would not be operating at its optimal speed. One alternative has been to allow the speed to be adjusted upon installation of the controller with the security gate. However, this relied on the judgment of the dealer installing the system or the owner of the system. In such situations it has been found that they all tend to set the speed of movement of the gate at an excessive speed that tends to cause damage to the gate and injury to those using the system. This in turn has naturally resulted in product liability claims and other problems. Thus, to avoid these problems most security gate manufactures preset the speed the controller will operate at to one that will be safe for the intended installation or to the slowest safe speed. 
   Thus, what is needed is a system and method that will allow for the setting of the optimal safe speed for a security gate to operate at. Such a system and method should be fail safe and allow of the automatic setting of the fastest safe speed the particular gate the controller is being installed at can operate at. 
   SUMMARY 
   It is an objective of the present invention to provide a system and method that allows the setting of a safe speed for a gate to operate at while still operating at its optimal fastest speed. It is an additional objective to provide a system that is tamper proof, and can sense the size of the gate and set the appropriate speed of operation, based on various preset criterion. 
   The present invention accomplishes these and other objectives by providing a barrier movement control apparatus, the apparatus that has: a) an ultrasonic measurement device positioned to measure a length of a barrier; b) an analysis unit to determine various characteristics of the barrier in communicative connection with the ultrasonic measurement device which generates a state signal based on information obtained from the ultrasonic measurement unit; and c) a barrier control unit responsive to a state signal from the analysis unit which controls the barrier operational characteristics based on the state signal. 
   In an additional aspect of the present invention ultrasonic measurement device can be selected from a group of: a master and slave unit positioned for measurement of the length of the barrier; a transceiver reflector unit positioned for measurement of the length of the barrier; or a transmitter unit, reflector unit and sensor unit positioned for measurement of the length of the barrier. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood by an examination of the following description, together with the accompanying drawings, in which: 
       FIG. 1  is a graph of a gate speed profile for gate length based a calculation using gate length and mass; 
       FIG. 1A  is a flowchart of a method for determining and setting speed based on the graph in  FIG. 1   
       FIGS. 2A ,  2 B and  2 C are three examples of gate time movement profiles based on the length of the gate; 
       FIG. 3  is a schematic diagram of a first example of an installation of the ultrasonic measurement device of the present invention; 
       FIG. 4  is a schematic diagram of a second example of an installation of the ultrasonic measurement device of the present invention; 
       FIG. 5  is a schematic diagram of a third example of an installation of the ultrasonic measurement device of the present invention; 
       FIG. 6  provides a cut away a hollow gate strut with an ultrasonic measurement incorporated therein; and 
       FIG. 7 . is schematic diagram of a security gate installation that incorporates the strut of  FIG. 6 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The present invention provides a method and apparatus that sets the optimal operational speed of a security gate or barrier, by providing a system that upon installation determines the length and if necessary the mass of the gate. Length of the gate is determined by use of ultrasonic based measuring devices to be discussed in detail below. Mass can be determined in a variety of different ways. Some of the systems and methods that can be used to determine mass are disclosed in co-pending patent applications owned by the applicant herein with Ser. Nos. 10/280,523 and 10/280,524 filed on Oct. 24, 2002, which applications are incorporated herein by reference as if set forth herein at length. 
   The system includes a method of calculating an optimal speed graph  21  as depicted in  FIG. 1 . In  FIG. 1  speed of movement is set out along the Y-axis and gate length is set along the X-axis In its simplest form the optimal speed graph  21  of a gate is a straight-line graph that is determined by a combination of the mass M of a particular gate, its length L and a constant K. Thus speed is calculated by the system with the following equation:
 
Speed= M*L+K   (w/o mass)
 
Speed= M L W+K   (With Mass [W])
 
   The system based on the above equation then calculates a speed graph as depicted in  FIG. 1  and based on this graph and the gate length, sets the maximum speed the gate can safely and optimally operate at. 
   For example, in one setup, the system could be calibrated so that a gate eight feet long, would optimally move between the open and closed position in eight seconds, and optimally, a gate twenty feet long would move between the open and closed positions in thirteen seconds. Based on the set values for an 8 foot and 20 foot gate, the mathematical formula for a straight line can be calculated as depicted in  FIG. 1 . In this situation we would consider the “proportional linear operator” as a slope of the line. This would be calculated by as follows; where X equals the distance and Y equals the time of movement: 
   
     
       
         
           M 
           = 
           
             Slope 
             = 
             
               
                 
                   
                     13 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     sec 
                   
                   - 
                   
                     8 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     sec 
                   
                 
                 
                   20 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     ft 
                     . 
                     
                       - 
                       8 
                     
                   
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   ft 
                 
               
               = 
               
                 0.416 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 
                   sec 
                   ft 
                 
               
             
           
         
       
     
   
   Since we are working with an equation for a straight line, i.e. Y=MX+B the value for B such as an offset would have to be calculated, and that would be as follows:
 
 B =offset=−( M ·length @8 sec−8 sec)=4.672
 
   
     
       
         
           DesiredSpeed 
           = 
           
             
               
                 ( 
                 
                   0.416 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     sec 
                     ft 
                   
                 
                 ) 
               
               · 
               
                 ( 
                 legthofgate 
                 ) 
               
             
             + 
             4.672 
           
         
       
     
   
   The above formula would have two constants proportionality to M in seconds per feet and an offset term of B in seconds. The values of M and B will be determined by the maximum and minimum desired speed of operation for maximum and minimum length of the gate. A CPU would then be able to calculate the speed as indicated in the flowchart  FIG. 1A . The measure of the gate length would be determined  91 . If the gate length was less than the minimum length the CPU would use the minimal length for a calculation of L  93 . However, if the gate was not less than the minimal length, it would move to step  94 , and if it determined it was a maximum length or greater it would use the maximum length for L, thus the speed  96  would be accordingly calculated. There, obviously, being a lower limit of eight seconds for a gate eight feet or shorter, and there would be a maximum speed of thirteen seconds for a gate of twenty feet or longer. For lengths in between, the system would set the speed as indicated in the graph in  FIG. 1  by the method set forth in  FIG. 1A . 
   The system and method of the present invention uses ultrasonic or ultrasound transmissions to measure the length of a gate. Ultrasonic or ultrasound, as is well known in the art, are sound wave transmissions beyond the range of the human hearing. Such sound transmissions are greater than 20,000 Hz. Ultrasound or ultrasonic transmissions offer a number of advantages in that they are not substantially affected by weather, visibility and can be made benign with respect to human contact. Additionally, they offer a very precise measurement tool. A detailed description of ultrasonic or ultrasound transmitters, transceivers or reflective medium is not included herein since these are well known in the art. 
     FIG. 2  provides three graphs of speed of operation profiles of gates of varying length in sub  FIGS. 2A ,  2 B and  2 C. Speed of operation of each gate is set out along the Y-axis and the time each gate takes to move between the open and closed position or visa versa is set out along the X-axis. As can be seen the longest gate  23   FIG. 2A  takes 20 seconds to move between the open and closed position. Also, its top speed as can be seen from graph is only at point  1  on graph  2 A. By contrast the profile of operation of a medium sized gate  25  depicted in  FIG. 2B  moves between the open and closed position within 10 seconds and reaches a higher speed at point  2 . Finally, the shortest gate  27   FIG. 2C  reaches a faster speed at point  3  and moves between the closed and open position within 8 seconds. 
     FIG. 3  provides one view of an installation of one version of the ultrasonic measuring device of the present invention with road or driveway  31 , fixed fence  33 , movable gate  35  and gate controller  37 . Additionally, an ultrasonic transceiver  39  is positioned on the gate controller  37  and an ultrasonic reflective medium  40  is positioned on the opposite side of gate  35 . Thus, when ultrasonic transceiver  39  generates ultrasonic waves, which it will do during installation or any time there after, it will reflect of off reflective medium  40  and be reflected back to transceiver  37 . In the typical case an analysis unit  43  will determine the length of the gate by the travel time of the waves between transceiver  39  and reflective medium  40 . The gate motor and gear system that translates the power generated by the motor to move arm  44  to swing open gate  35  is not shown since such aspects of the system are well known in the art. 
     FIG. 4  depicts another version of the ultrasonic measurement device. Only the aspects of the device depicted in  FIG. 4  that are different from  FIG. 3  are given new reference numbers the rest are the same as  FIG. 3 . In  FIG. 4  an ultrasonic transmitter  51  is positioned on gate utility box  51 and beams ultrasonic waves towards slave unit  53  located at the other end of gate  35 . Slave unit  53  is communicatively connected by line  55  to master transmitter unit  51 . Upon receipt by slave unit  53  of ultrasonic transmissions slave unit  53  transmits this information to master unit  53  by connection  55 . Based on this information analysis unit  44  can calculate the length of the gate. In  FIG. 4  gate  35  is a double swinging gate. 
     FIG. 5  depicts a third version of the ultrasonic measuring device in this case it consists of an ultrasonic transmitter  71 , reflective medium  73  and a separate ultrasonic sensor  75 . The information on the time it takes the ultrasonic signal to move from transmitter  71  reflects off of  73  and is received by sensor  75 . Analysis unit  44  based on this information can make a determination as to length of gate  35 . 
     FIG. 6  depicts another variation that the set up the ultrasonic measurement device can take. In this variation a transceiver  71  is located in the hollow strut of the gate structure itself.  FIG. 6  being a cut away view of a gate strut. The ultrasonic waves generated by transceiver  79  would travel down strut  81  reflect off of the inside end  85  and the echo would be detected by transceiver  79 . Analysis unit  83  would make the appropriate calculations to determine length and communicate it to the gate operator.  FIG. 7  is a view of a gate  91  that is formed in part by strut  81 . Transceiver  79  would transmit ultrasonic waves down strut  81  to its end  85  that would reflect it back to transceiver  79  that would pick up the reflected waves. In many cases gates of this type are made of extruded aluminum with a hollow core to provide a strong durable gate that is also relatively light and easy to move. 
   Another method for calculating the optimal speed for opening and closing the gate based on its length which uses a straight line approximation as used above is as follows:
 
Given the formula:  Y=M*X+B  for a straight line equation
 
   Where Y=calculated point 
   And M=(Ymax−Ymin)/(Xmax−Xmin) 
   Given Y=min and max time (or alternatively torque, motor speed, etc.) 
   And X=min and max length of gate (or alternatively mass * length) 
   And B=Ymax−M*Xmax 
   The optimal speed can be calculated between the minimum and maximum speeds once the length of the gate is known. If the equation&#39;s X component is written for length and mass, then mass is determined and multiplied by the length. For this example, we will just use length and enter Y as time in seconds. 
   Given: Ymax=15 seconds for gate length Xmax of 20 feet and Ymin=8 seconds for gate length Xmin of 6 feet.
 
 M= (15−8)/(20−6)=7/14=0.5
 
 B= 15−(0.5*20)=15−10=5
 
   If the gate length X is determined to be 12 feet, then the optimal speed Y=0.5*12+5 is calculated to be 11 seconds. Keep in mind that Y is not restricted to time in seconds but could be calculated to produce desired torque or motor speed or any other value that will accomplish the optimal time to open or close the gate. 
   A software example in psuedo code is provided: 
   
     
       
             
             
             
           
             
             
             
           
         
             
                 
                 
             
           
           
             
                 
               #define M 
               0.5 
             
             
                 
               #define B 
               5 
             
             
                 
               #define Xmax 20 
             
             
                 
               #define Xmin 
               6 
             
           
        
         
             
                 
               GetGateLength (X); 
               //read the gate length - &gt; X 
             
             
                 
               If (X &gt; Xmax) 
               // check for min and max lengths 
             
             
                 
                X = Xmax; 
             
             
                 
               If (X &lt; Xmin) 
             
             
                 
                X = Xmin; 
             
             
                 
               GateTime = X * M + B; 
               //calculate optimal speed 
             
             
                 
               OpenGate (GateTime); 
               // move the gate at calculated speed 
             
             
                 
                 
             
           
        
       
     
   
   While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and detail may be made to it without departing from the spirit and scope of the invention.