Abstract:
A barrier movement operator moves a barrier between open and closed positions. The operator receives a first request to move the barrier. The actual force required to move the barrier is measured. An obstruction to barrier movement is determined by comparing the measured actual force to a first predetermined force threshold. Responsive to the detection of an obstruction, the direction of travel of the barrier is reversed. The operation of the barrier movement operator is modified, by permitting the use of a higher force threshold in future measurements. A second request to move the barrier is received. The actual force required to move the barrier is measured a second time. An obstruction to barrier movement is detected by comparing the measured actual force with the new, higher force threshold.

Description:
FIELD 
   The field of the invention generally relates to methods and devices for controlling moveable barrier operators. More particularly, the invention relates to adapting the operation of the barrier to detect and overcome nuisance obstructions. 
   BACKGROUND 
   Barrier movement operators are automated systems which are used to move a barrier with respect to an opening. Examples of the barriers to be moved include garage doors, gates, fire doors and rolling shutters. The primary examples herein involve garage door operators but the principles described and claimed therein relate to all barrier movement operators. A number of barrier movement operators have been sold over the years most of which include a head unit containing a motor connected to a transmission. The transmission, which may include, for example, a belt drive, a chain drive, a screw drive or extendible arm is then coupled to the barrier for opening and closing. 
   Such barrier movement operators also typically include a wall control unit, which is connected to send signals to the head unit thereby causing the head unit to open and close the barrier. In addition, these operators often include a receiver unit at the head unit to receive wireless transmissions from a hand-held code transmitter or from a keypad transmitter, which maybe affixed to the outside of the area closed by the barrier or other structure. 
   As barrier movement operators open and close the barriers, the barrier may come into contact with an obstruction. Previous systems have allowed the barrier operator systems to determine if an obstruction has been encountered and to either stop or reverse the direction of the travel of the barrier once this determination has been made. For instance, some previous systems measured the force applied to the barrier by the motor. The systems then compared the measured force to an expected value plus a fixed cushion value. If the comparison indicated that the measurement value exceeded the expected value plus the cushion value (together, a threshold value), then the downward barrier movement was reversed. These systems typically determined the force by measuring the barrier speed or current in the motor and then calculated the force using these measurements. 
   Secondary obstruction detectors have also been used to detect obstructions in the path of the barrier. For instance, infrared (IR) detectors and barrier edge sensors have been used to determine if an obstruction exists in the path of the barrier. Typically, if the secondary obstruction detector indicated that an obstruction was present, the downward movement of the barrier was halted and then reversed in previous systems. 
   As system components age and are subjected to various environmental conditions and the system is not properly maintained, errors in the operation of previous systems may occur. For instance, if force measurements are made, the measured force may exceed the threshold value, but the door may not be encountering a real obstruction. In this case, the downward movement of the door would be reversed even though there was no actual obstruction present in the path of the barrier. For example, a nuisance such as sand or dirt maybe present in the guiding apparatus of the door path. In other examples, the door may have not been lubricated or may have worn parts. In summary, present systems are not capable of adapting their performance over time to determine if a real obstruction exists or whether the barrier reversal was caused by a nuisance or mistake. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a system and method for operating a barrier movement operator between open and closed positions. The system and method determines if an obstruction is truly present in the barrier and stops and potentially reverses the direction of travel if an obstruction is detected. The detection and determination is accomplished by measuring the force applied to the barrier and comparing this measured force to a threshold. After the direction of travel of the barrier is reversed, a request is made to move the barrier downward, the barrier is moved downward, and the force applied to the barrier is compared to a new, higher threshold. The request may be made by pressing and then releasing an actuator device such as a button or switch. The barrier travel direction may be reversed again if the second test indicates that the measured force exceeds the new threshold. If the barrier reaches the end of its path, it is determined that an obstruction did not really exist in the path of the barrier. 
   In many of the embodiments, a barrier movement operator moves a barrier between open and closed positions. The operator receives a first request to move the barrier. The force required to move the barrier is measured. Whether an obstruction to barrier movement exists is determined by comparing the measured actual force to a first predetermined force threshold. Responsive to the detection of an obstruction, the direction of travel of the barrier is stopped and potentially reversed. The operation of the barrier movement operator is modified, by permitting the use of a higher force threshold in future measurements and comparisons. 
   A second request to move the barrier is then received. The actual force required to move the barrier is measured a second time. An obstruction to barrier movement is detected by comparing the measured actual force with the new, higher force threshold. 
   The modification of the force threshold may be reversed upon completion of the barrier movement in response to the second request without detecting an obstruction. Alternatively, the new force threshold may be made permanent. 
   In other approaches, a user is allowed a predetermined time to make the second request for the barrier movement. If the request is received within the time period, the system may use a modified, new threshold value in the comparisons performed. If the request is not received within the specified time period, the system may use the old threshold in the comparisons. In still another approach, the system may also test for obstructions using secondary obstruction detectors such as IR sensors and use this information together with the threshold comparison to determine whether an obstruction exists. 
   Thus, a method and system to determine obstructions in the path of a barrier is adaptable to environmental and other conditions and changes in system components. In this regard, a new threshold is used to determine whether an actual obstruction exists in the path of the closing barrier or whether an alleged obstruction does not exist and the barrier can be safely closed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a garage door opening system according to the present invention; 
       FIG. 2  is a block diagram of a controller for use in a barrier opening system according to the present invention; 
       FIG. 3   a  is a flowchart illustrating the operation of the barrier opening system using a temporary threshold according to the present invention; 
       FIG. 3   b  is a flowchart illustrating the operation of the barrier opening system using a permanent threshold according to the present invention; 
       FIG. 4   a  is a flowchart illustrating the operation of the barrier opening system using a temporary threshold according to the present invention; and 
       FIG. 4   b  is a flowchart illustrating the operation of the barrier opening system using a permanent threshold according to the present invention. 
   

   Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are typically not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. 
   DETAILED DESCRIPTION 
   For illustrative purposes, the following description refers to a moveable barrier that is a garage door. However, it will be understood by those skilled in the art that the moveable barrier may not only be a garage door but may be any type of barrier such as a fire door, shutter, window, gate. Other examples of barriers are possible. 
   Referring now to the drawings and especially to  FIG. 1 , a movable barrier operator, which is a garage door operator, is generally shown therein and includes a head unit  12  mounted within a garage  14 . More specifically, the head unit  12  is mounted to the ceiling of the garage  14  and includes a rail  18  extending therefrom with a releasable trolley  20  attached having an arm  22  extending to a multiple paneled garage door  24  positioned for movement along a pair of door rails  26  and  28 . The system includes a hand-held transmitter unit  30  adapted to send signals to an antenna  32  positioned on the head unit  12  as will appear hereinafter. An external control pad  34  is positioned on the outside of the garage having a plurality of buttons thereon and communicates via radio frequency transmission with the antenna  32  of the head unit  12 . An optical emitter  42  is connected via a power and signal line  44  to the head unit. An optical detector  46  is connected via a wire  48  to the head unit  12 . The head unit  12  also includes a receiver unit  102 . The receiver unit  102  receives a wireless signal, which is used to actuate the garage door opener. 
   The head unit  12  has the wall control panel  43  connected to it via a wire or line  43 A. The wall control panel  43  includes a decoder, which decodes closures of a lock switch  80 , a learn switch  82  and a command switch  84  in the wall circuit. The wall control panel  43  also includes a light emitting diode  86  connected by a resistor to the line  43  and to ground to indicate that the wall control panel  43  is energized by the head unit  12 . Switch closures are decoded by the decoder, which sends signals along lines  43 A to a control unit  200  coupled via control lines to an electric motor positioned within the head unit  12 . In other embodiments, analog signals may be exchanged between wall control  43  and head unit  12 . 
   The wall control panel  43  is placed in a position such that an operator can observe the garage door  24 . In this respect, the control panel  43  may be in a fixed position. However, it may also be moveable as well. The wall control panel  43  may also use a wirelessly coupled connection to the head unit  12  instead of the wire  43 A. As discussed below, control unit  200  of head unit  12  determines the applied force or a value representative of the applied force to the door  24  (both referred to herein as the “measured force”) and compares this to an expected value plus a variable cushion value (together, the threshold value, which is variable). Based upon the results of the comparison, the direction of the door travel may be reversed. A user may then press and release an actuator device, for example, the command switch  84 . The direction of travel of the door  24  is again be reversed and a new threshold can be used and compared to the measured force. The new threshold value may be a higher threshold value than the old threshold. However, in other circumstances, a lower threshold value may be used. The threshold value may be adjusted by altering the cushion value and recalculating the threshold or simply directly altering the threshold. 
   In one approach, a time limit is set for the actuator device to be actuated and the threshold is adjusted if the actuator device is actuated within the time limit. Otherwise, the threshold may remain unchanged. 
   Based upon the results of comparing the measured force to the new threshold, an obstruction may be detected, the door movement may be halted, and then reversed. Alternatively, the door  24  may travel to the end of its path indicating that an obstruction does not exist. In another approach and as described elsewhere in this specification, a secondary obstruction detector, for instance, sensor  46 , maybe used in conjunction with a force measurement to determine whether an obstruction exists in the path of the door  24 . 
   Referring now to  FIG. 2 , an example of the control unit  200  is described. The control unit  200  includes a memory  202  and a controller  204 . The controller  204  receives control signals from a current sensor  206  and a speed sensor  208 . The current sensor  206  indicates the amount of electrical current that is present in a motor  212  of a moveable barrier operator. The speed sensor  208  indicates how quickly a door  214  is moving in a downward direction. The controller  204  receives these measurements from the sensors and from these measurements determines a value representing the amount of force being applied to the door  214 . 
   As described elsewhere in this specification, the controller  204  compares the measured force to a threshold value. The measured force may be a value representative of force. For instance, it may be a speed of the motor or barrier or it may be the amount of current going to the motor sensed by the sensors. Alternatively, the system may actually calculate a force from these or other measurements. The expected force and threshold values are stored in the memory  202 . As also explained elsewhere in the specification, the door  214  is initially moved in a downward direction. Upon exceeding the threshold value the controller will cause the door to stop and/or reverse its direction. In order to test and possibly clear the second obstruction the user momentarily presses and then releases an actuator  216  (switch  84 ) and the door  214  proceeds again in a downward direction and a new threshold may be used in comparison. If the new threshold value is exceeded, the direction of movement of the barrier is again reversed and it is determined that an obstruction existed in the path of the door  214 . The new threshold may replace the old threshold in the memory  202  or the threshold may revert to the old threshold value. 
   A secondary obstruction detector  210  (optical emitter  42  and detector  46 ) may also be used. For example, the secondary detector  210  may be an IR detector, an optical motion detector, an acoustic motion detector, an RF motion detector, or a door edge detector. Other types of secondary obstruction detectors are possible. 
   The secondary obstruction detector  210  is used to verify the decision made by operator. In this regard, the controller  204  receives a signal from the secondary obstruction detector  210 . If the detector  210  indicates that an obstruction exists and the operator insists on moving the door in a downward direction, then the old force threshold is used. In another example, the threshold will not be changed to a new threshold unless a secondary obstruction detector is being used and the secondary obstruction detector verifies that an obstruction exists. In this case, the threshold is changed and a verification can be performed indicating that both the secondary obstruction detector and the force comparisons indicate that an obstruction exists. 
   Referring now to  FIG. 3   a,  an example of an approach that adjusts the force threshold is described. At step  302 , the system measures the present force or value representing force being applied. The force or a value representing force may be determined by measuring several different system values. For instance, the system may measure the door speed by watching how fast markers (e.g. slits) move past a point or by measuring current in the motor. The speed or current representation is then used to calculate a value representing the force. At step  304 , the system determines if the present measured force is less than a threshold value. If the answer at step  304  is affirmative, then execution continues at step  303 . If the answer is negative at step  306 , door movement in the downward direction is halted and movement of the door is reversed to an upward direction. At step  303 , the system determines if limits were reached. If the answer is affirmative, execution ends. If the answer is negative, execution continues with step  302 . 
   At step  307 , it is determined whether the door has reached the closed position. If the answer is affirmative, control continues at step  320 . If the answer is negative, control continues at step  308 . 
   At step  308 , the system waits for a control button to be actuated by a user. For example, the button may be a command button. At step  310 , the system determines if the command signal created by the actuation of the button has been received. If the answer is negative, control returns to step  308 . If the answer is affirmative, control continues at step  312  where the threshold is increased to a new value. 
   At step  314 , the door is sent downward and the force being applied to the door is measured. At step  316 , the system determines if the present measured force is less than the threshold value. If the answer is affirmative, control continues at step  314 . If the answer is negative, control continues at step  318  where the direction of travel of the door is reversed. At this point, it can be determined that a valid obstruction has been detected. At step  320 , the threshold is returned to the old threshold value. 
   Referring now to  FIG. 3   b,  an example of an approach that adjusts the force threshold and uses the new threshold as a permanent value is described. At step  352 , the system measures the present force or a value representing force being applied. The force or value representing force may be determined by measuring several different system values. For instance, the system may measure the door speed by watching how fast markers (e.g. slits) move past a point or by measuring current in the motor. The speed (or current) is then used to calculate the force. At step  354 , the system determines if the present measured force is less than a threshold value. If the answer at step  354  is affirmative, then execution continues at step  353 . If the answer is negative at step  356 , door movement in the downward direction is halted and movement of the door is reversed to an upward direction. At step  353 , the system determines if limits were reached. If the answer is affirmative, execution ends. If the answer is negative, execution continues with step  352 . 
   At step  357 , it is determined whether the door has reached the closed position. If the answer is affirmative, control continues at step  370 . If the answer is negative, control continues at step  358 . 
   At step  358 , the system waits for a control button to be actuated by a user. For example, the button may be a command button. At step  360 , the system determines if the command signal created by the actuation of the button has been received. If the answer is negative, control returns to step  358 . If the answer is affirmative, control continues at step  362  where the threshold is changed increased to a new temporary value. For instance, the system may increase the threshold value to a new higher value. 
   At step  364 , the door is sent downward and the force being applied to the door is measured. At step  366 , the system determines if the present measured force is less than the updated threshold. If the answer is affirmative, control continues at step  364 . If the answer at step  366  is negative, control continues at step  368  where the direction of travel of the door is reversed. At this point, it can be determined that a valid obstruction has been detected. If the answer at step  366  is affirmative, control continues at step  367 . 
   At step  367 , it is determined whether the door has reached the closed position. If the answer is affirmative, control continues at step  370 . If the answer at step  367  is negative, control continues at step  364 . At step  370 , the threshold is permanently changed to the new threshold value. 
   Referring now to  FIG. 4   a,  an example of an approach that adjusts the force threshold is described. At step  402 , the system measures the present force or a value representing force being applied. The force or the value representing force may be determined by measuring several different system values. For instance, the system may measure the door speed by watching how fast markers (e.g. slits) move past a point or by measuring current in the motor. The speed (or current) is then used to calculate the force. At step  404 , the system determines if the present measured force is less than a threshold value. If the answer at step  404  is affirmative, then execution continues at step  403 . At step  403 , the system determines if limits were reached. If the answer is affirmative, execution ends. If the answer is negative, execution continues with step  402 . 
   If the answer is negative at step  406 , door movement in the downward direction is halted and movement of the door is reversed to an upward direction. At step  407 , it is determined whether the door has reached the closed position. If the answer is affirmative, control continues at step  422 . If the answer is negative, control continues at step  408 . 
   At step  408 , a predetermined waiting time is determined. This value maybe set by a user and it may be measured from the initial detection of an obstruction at step  404 . At step  410 , the system determines if the command signal created by the actuation of a command button has been received within the time window set at step  408 . If the answer is negative, control returns to step  414  where the threshold value remains unchanged. If the answer is affirmative, control continues at step  412  where the threshold is changed or increased to a new temporary value. For instance, the system may increase the threshold value to a new higher value. 
   At step  416 , the door is sent downward and the force being applied to the door is measured. At step  418 , the system determines if the present measured force is less than the updated threshold (either a higher threshold or original threshold). If the answer is affirmative, control continues at step  416 . If the answer is negative, control continues at step  420  where the direction of travel of the door is reversed. At this point, it can be determined that a valid obstruction has been detected. At step  422 , the threshold is returned to the old threshold value. 
   Referring now to  FIG. 4   b,  an example of an approach that adjusts the force threshold and uses the new threshold as a permanent value is described. At step  452 , the system measures the present force or a value representing force being applied. The force or the value representing force may be determined by measuring several different system values. For instance, the system may measure the door speed by watching how fast markers (e.g. slits) move past a point or by measuring current in the motor. The speed (or current) is then used to calculate the force. At step  454 , the system determines if the present measured force is less than a threshold value. If the answer at step  454  is affirmative, then execution continues at step  453 . If the answer is negative at step  454 , door movement in the downward direction is halted and movement of the door is reversed to an upward direction. At step  453 , the system determines if limits were reached. If the answer is affirmative, execution ends. If the answer is negative, execution continues with step  452 . 
   At step  457 , it is determined whether the door has reached the closed position. If the answer is affirmative, control continues at step  472 . If the answer is negative, control continues at step  458 . 
   At step  458 , a predetermined waiting time is determined. This value maybe set by a user and it may be measured from the initial detection of an obstruction at step  454 . At step  460 , the system determines if the command signal created by the actuation of a command button has been received within the time window set at step  458 . If the answer is negative, control returns to step  464  where the threshold value remains unchanged. If the answer is affirmative, control continues at step  462  where the threshold is changed or increased to a new temporary value. For instance, the system may increase the threshold value to a new higher value. 
   At step  466 , the door is sent downward and the force being applied to the door is measured. At step  468 , the system determines if the present measured force is less than the updated threshold (either a higher threshold or original threshold). If the answer at step  468  is negative, control continues at step  470  where the direction of travel of the door is reversed. At this point, it can be determined that a valid obstruction has been detected. If the answer at step  468  is affirmative, control continues at step  469 . 
   At step  469 , it is determined whether the door has reached the closed position. If the answer is affirmative, control continues at step  472 . If the answer at step  367  is negative, control continues at step  466 . At step  472 , the threshold is permanently changed to the new threshold value. 
   For the approaches described in  FIGS. 3–4 , a test may be made for a secondary obstruction detector may be made. If the test for the secondary obstruction detector indicates that the detector exists and is functioning correctly, then a new threshold maybe used as described above in relation to these figures. However, if the test indicates that a secondary obstruction detector is not being used, then no new threshold value is used. In this case, the test can be performed again to determine if an obstruction is still determined to exist. In another example, the secondary obstruction detector protects against human operator errors. If the secondary obstruction operator indicates than an obstruction exists, any forcing down of the door by the operator by pressing the control button will utilize the old threshold value. In other words, the new threshold value will not be used. 
   While there have been illustrated and described particular embodiments of the present invention, it will be appreciated that numerous changes and modifications will occur to those skilled in the art, and it is intended in the appended claims to cover all those changes and modifications which fall within the true spirit and scope of the present invention.