Abstract:
A movable barrier operator includes an absolute position detector which provides a unique value for each position of the barrier along its path of travel. The absolute position detector employs multiple binary serial streams and one multiple clock stream. After the first five cycles of the clock stream, the binary streams can be decoded by a processor to produce an absolute position. Every clock edge produces a new absolute position along the path of travel.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to operators for movable barriers, such as rolling shutters, retractable awnings, gates, garage doors, overhead doors and the like, and more particularly to operators which can determine the absolute position of the barrier at all times, including after a power outage and subsequent manual relocation of the barrier.  
           [0003]    2. Description of Related Art  
           [0004]    One of the problems which must be addressed in designing and engineering operators for movable barriers is the provision of barrier position detection. Most electronic positioning systems used in barrier operators keep track of the barrier&#39;s position by incrementing a position counter during one direction of travel and decrementing the position counter during the opposite direction of travel. This can cause errors if there are missed pulses or extraneous pulses during travel (such as from slippage of the barrier or motor).  
           [0005]    Some barrier position detection systems employ a pass point. The pass point corresponds to a fixed location on the barrier, so that whenever the barrier moves past the pass point, the position detector is normalized or calibrated. By normalizing or zeroing out the position detector (or counter), the effects of missed pulses or slippage are eliminated. Some systems employ multiple pass points which provide further error removal capability. The pass point is a good solution in most situations, such as for garage door operators, which seldom move manually.  
           [0006]    A more significant problem can occur in motorized awnings or rolling shutters. The rolling shutter assembly is frequently installed in a housing which is built into a wall. If power goes out on a rolling shutter system, the user will frequently move the rolling shutter manually to either open or close it. The power is off, but the gears of the positioning system move without power applied to assure manual override of an electric system for the purpose of power failures. Some users may also decide for convenience to move the shutter manually. When power returns, if the rolling shutter has been manually moved past all pass points, the operator, not encountering the pass point reference, may cause the rolling shutter to continue to move completely into the housing necessitating removal of the shutter from the housing. Removal of the rolling shutter from the housing frequently means removing a portion of an interior wall.  
           [0007]    There is a need for a movable barrier operator with a position indicating system that provides the absolute position of the barrier, even after power outages or after the barrier has been moved manually. There is a need for a movable barrier operator which can unambiguously determine the position of the barrier after power is applied. There is a need for a movable barrier operator which can unambiguously determine the position of the barrier regardless of direction of travel.  
         SUMMARY OF THE INVENTION  
         [0008]    A barrier operator position detector includes a first rotary member which is encoded to generate a first N bit subcode selected from N sequential bits of a M bit code word. The first N bit subcode has the property that every selected subcode of N sequential bits of the M bit code word has a unique value. N is greater than 1 and preferably 5. M is greater than N and preferably 32. A second rotary member is encoded to generate a second N bit subcode selected from N sequential bits of a M-1 bit code word, the second N bit subcode also has the property that every selected subcode of N sequential bits of the M-1 bit code word has a unique value (preferably M-1 is 31). A controller, responsive to the first subcode and the second subcode, generates a 2N bit multibit (or two N-bit subcodes) code. The 2N It multibit subcode is representative of a unique position output, which can be decoded into a unique position of the barrier along its travel.  
           [0009]    A movable barrier operator according to the invention includes an absolute position detector which provides a unique value for each position of the barrier along its path of travel. The absolute position detector employs two binary serial streams and one clock stream. After the first five cycles of the clock stream, the binary serial streams can be decoded by a microprocessor or other processor to produce an absolute position indication. Every clock edge produces a new absolute position value along the path of travel.  
           [0010]    The absolute position detector employs three wheels; two data wheels and a clock wheel driven by a pinon. Each wheel rotates near a wheel state detector which produces digital signals comprising bit streams. Preferably an infrared emitter-sensor pair is used as the wheel state detector. However, any electromechanical system which produces a digital signal comprising bit streams, such as Hall sensors, laser discs, and so on, may be used. For convenience, the absolute position detector of the invention well be described in detail with reference only to the infrared emitter-sensor embodiment.  
           [0011]    In the preferred embodiment, two of the wheels are data wheels or gears and have teeth distributed around their outer portions. One wheel has 32 teeth, the other wheel has 31 teeth. Each tooth of each data wheel has a corresponding data bit formed in the wheel before the tooth. Each data bit represents a single binary data bit. A space formed below a tooth represents a digital low; a solid area formed below the tooth represents a digital high. The 32 teeth wheel has a 32 bit binary stream formed in it. The stream is uniquely defined so that any consecutive 5 bits in the stream are different from any other consecutive 5 bits in the stream, including the rollover stream. The 31 teeth wheel is similarly defined, except the 31 teeth wheel has the same bit binary stream as the 32 bit wheel, with one bit missing.  
           [0012]    Since the 32 teeth wheel and the 31 teeth wheel have different numbers of teeth and are driven by the same pinion, they rotate at different speeds. The pinion is driven externally by a searing system that is driven by the motor. The motor can rotate clockwise or counterclockwise, so the pinion can also turn in both directions. Since the motor is bi-directional, an attached load comprising a barrier such as a door, awning, shutter or gate can move in either of two opposite directions. Preferably direction of travel information is obtained by storing the commanded direction of travel (i.e., the user commands the door to open by pushing the open button or to close by pushing a close button).  
           [0013]    The movable barrier is operated through linear linkage of the load to the motor such as a trolley, or through rotational linkage to the motor, where the load is wound around the entire operator unit, such as in a rolling shutters. Since the two data wheels rotate at different speeds (because of the different number of teeth), the two binary streams have different repeat rates. This means that a given 5 bit streams from the 32 teeth wheel will not combine with the corresponding 5 bit stream from the 31 teeth wheel until 31 more revolutions of the 32 teeth wheel, or vice versa. In other words, a total of 31×32=992 unique two word values are possible without a rollover or repeated position concern. 992 unique positions is large enough to provide absolute position along a part of a movable barrier in most situations. An extra data wheel may be added for more positions (i.e., 32×31×30=29,760 positions). This mechanical linkage also means if the unit is moved manually, the 31 bit wheel and the 32 bit wheel will move, storing or representing for later reading by the controller, the position of the awning, door or shutter.  
           [0014]    The third wheel is a clock wheel and is used to provide a clock signal for the position detecting system to enable proper sampling of the data wheel bit streams. The clock wheel includes 32 equally spaced openings. The clock wheel provides a digital low pulse signal when the center of a data bit on the 32 teeth wheel lines up with the center of a data bit on the 31 teeth wheel and when these centers are in line with the IR sensors. The clock signal is provided to the microprocessor which uses the clock signal as an interrupt to sample binary data from emitter-receiver pair associated with each data wheel. After the first 5 clock cycles, each data wheel has output a 5 digit binary stream, which when combined, gives 2 five digit binary numbers. This 5 digit binary number pair is decoded by the microprocessor which calculates an absolute position. Thereafter, every clock cycle triggers the sampling of a new binary digit from each wheel, the stored 5 bit binary number pair is updated, and a new absolute position of the barrier is determined.  
           [0015]    The movable barrier operator according to the invention with absolute position detector (or encoder system) provides many advantages. It provides the absolute position of the barrier for every pulse edge of the clock signal from positioning gears turned by motor&#39;s gearing system. Shortly after power is applied to the motor, the clock wheel would have produced 5 pulses. After 5 pulses, the encoder system determines the absolute position of the barrier. The encoder system can provide direction of travel after six pulses of the clock wheel. The encoder system discriminates false or unwanted pulses to prevent false positioning.  
           [0016]    An absolute position is always provided shortly after power is applied (after 5 pulses and the first 5 digit binary pair is obtained), regardless of the stored value of the last position and regardless of where the barrier may have been moved manually. The absolute position detector also provides an opportunity for the system to do a validity check for every newly calculated position (i.e., by checking the absolute position between successive data streams, the direction of travel can be ascertained). It should also be noted that no presetting of the wheels prior to installation/operation is required.  
           [0017]    Additional advantages and features of the invention may be appreciated from a perusal of the specification, including claims in light of the accompanying drawing. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 is a perspective view of a garage door operating system in accordance with an embodiment of the invention;  
         [0019]    [0019]FIG. 2 is a perspective view of a rolling shutter operating system in accordance with an alternative embodiment of the invention;  
         [0020]    [0020]FIG. 3 is a perspective view of the tubular motor assembly of FIG. 2;  
         [0021]    [0021]FIGS. 4 and 5 are two exploded perspective views of the location of the absolute position detector assembly shown in FIG. 3;  
         [0022]    [0022]FIG. 6 is an enlarged perspective view of the absolute position detector assembly of FIG. 4;  
         [0023]    [0023]FIG. 7 is a graph of the 32 bit data streams produced in each of the 31 bit wheel and 32 bit wheel;  
         [0024]    [0024]FIG. 8 is an example calculation of position using the 31 bit wheel and the 32 bit wheel;  
         [0025]    [0025]FIG. 9 is a flow chart of the routine run by the controller to sample the 5 bit data streams;  
         [0026]    [0026]FIG. 10 is a flow chart of the RPM routine used by the controller to sample the 5 bit data streams; and  
         [0027]    [0027]FIG. 11 is a schematic diagram of the electronics controlling the rolling shutter head unit of FIG. 2. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    Referring now to the drawings, and especially to FIG. 1, a movable barrier operator embodying the present invention is generally shown therein and identified by reference numeral  10 . The movable barrier operator  10  is employed for controlling the opening and closing of a conventional overhead garage door  12  of a garage  13 . The garage door  12  is mounted on guide rails  14  for movement between the closed position illustrated in FIG. 1 and an open or raised position. The garage  13  includes a ceiling  16  and a wall  18  defining an opening blocked by garage door  12 . As shown, guide rails  14  are mounted to wall  18  and ceiling  16  of the garage  13  in a conventional manner.  
         [0029]    A power drive unit or head, generally indicated at  20 , is mounted to the ceiling  16  in a conventional manner. An integrated drive rail  22  extends between the power drive unit  20  and the garage wall  18 . As can be seen in FIG. 1, one end of integrated drive rail  22  is mounted to a portion of the garage wall  18  located above the garage door  12 . An operator arm  26  is connected at one end to the garage door  12  and at the other end to a trolley  94  mounted for movement back and forth, along the integrated drive rail  22 . As will be seen herein, a motor in the power drive unit  20  propels the trolleys  94  in a desired manner to raise and lower garage door  12  via the coupling of the trolley  94  and the operator arm  26  to the garage door  12 .  
         [0030]    A push button control unit  32 , which includes an electronic controller and a keypad, is coupled by electrical conductors  34  to the power drive unit  20  and sends signals to the power drive unit, controlling operation of the drive motor therein. Preferably, the power drive unit  20  also includes a conventional radio receiver (not shown) for receiving radio signals from a remote control transmitter  38 . An optional auxiliary power drive unit  40  is shown coupled to one end of integrated drive rail  22 , being mounted on wall  18 , atop door  12 . If desired, operational flexibility of the integrated drive rail assembly may allow relocation of the main drive unit to a point adjacent the door.  
         [0031]    Referring now to FIG. 2, a barrier operator system employing an absolute position detector is employed for controlling the opening and closing of a conventional rolling shutter  112 . The rolling shutter is mounted on guide rails  114  for movement between the closed position illustrated in FIG. 2 and an open or raised position. The wall  118  defines an opening blocked or covered by rolling shutter  112 . As shown, guide rails  114  are mounted to wall  118  in a conventional manner.  
         [0032]    A power drive unit or head, generally indicated at  120 , is mounted to the top of frame  110  in a conventional manner. Although the head unit is shown as being mounted on the exterior, as noted above, in many applications, the head unit is built into the wall so the user sees only the shutters. In the two views shown in FIG. 2, the head unit  120  is shown mounted on opposite sides of the top of frame  110 . As will be seen herein, a motor in head unit  120  propels a sleeve or tube  142  to raise and lower rolling shutter  112  via the coupling of sleeve  142  to rolling shutter  112 .  
         [0033]    Control for head unit  120  may be as described above for garage door operator  20 , i.e., using a push button control or a keypad mounted at another location on a wall. Additionally, head unit may also include a conventional radio receiver (not shown) for receiving radio signals from a remote control transmitter. If desired, the head unit  120  may be mounted on either side of the frame  110 .  
         [0034]    As shown in FIGS. 3, 4 and  5 , head unit  120  includes a tubular housing  138  and end section  122  and  134 . Within the housing  138  is the motor  130  which includes an output shaft  131  coupled at one end to end section  134  and at the other end to driving gear assembly  132 . The output from gear assembly  132  is provided to output ring  140 , which is fixedly attached to outer sleeve  142 . Rolling shutters are attached to outer sleeve  142 , so that when motor  130  runs, outer sleeve  142  rotates, causing rolling shutters to open or close (depending on the direction of rotation of motor  130 ).  
         [0035]    Outer sleeve  142  is also fixedly attached to ring  136 . Ring  136  drives absolute position detector assembly  124 . Position detector assembly  124  is coupled to control board  144 . Control board  144  contains the electronics for starting and controlling motor  130  (see FIG. 11). Capacitor  126  is used to start motor  130  (described below). A brake  128  is provided to slow motor  130  when the rolling shutters are approaching a limit position.  
         [0036]    Referring to FIGS. 6 and 7, absolute position detector assembly  124  includes a clock wheel  206 , which is attached to axle  212  for rotation therewith. Axle  212  rests in supports  210 , and freely rotates therein, which are attached to board  140  by legs  240 . Clock wheel  206  includes 32 equally spaced openings  230 . The clock wheel  206  provides a digital low pulse signal when the center of a data bit on the 32 teeth wheel  202  lines up with the center of a data bit on the 31 teeth wheel  204  and when these centers are in line with the IR sensors—through an opening  230  (not shown). The clock signal is provided to the microprocessor which uses the clock signal as an interrupt to sample binary data from each data wheel. 32 bit wheel  202  is attached to axle  212  for rotation therewith. Each complete rotation of the 32 bit wheel  202  corresponds to one complete rotation of clock wheel  206 . 32 bit wheel  202  includes 32 teeth or gears  220 , which are driven by pinion  252  (see FIG. 4) which is driven by ring  136 . 31 bit wheel  204  includes 31 teeth or gears  222  which are also driven by pinion  252 . 31 bit wheel  204  freely spins about axle  202 . One turn of the 32 bit wheel  202  corresponds to 32/31 turns of the 31 bit wheel  204 .  
         [0037]    A unique bit stream pattern is formed in each of 32 bit wheel  202  and 31 bit wheel  204 . Beneath the teeth  220  are solid areas  226  and spaces  224 . A space under a tooth  220  corresponds to a 0; a solid area  226  correspond to a 1. The exact pattern is shown in FIG. 7. The first row of pulses are the 32 pulses generated by the clock wheel  206 . One complete revolution of the clock wheel generates 32 low pulses, representing sample time. The 31 bit wheel has solid and spaces areas which correspond to a 31 bit data steam: 1111000001110100010010101100110 as shown in the second row of FIG. 7. For every one complete revolution of the clock wheel, the 31 bit wheel produces the unique 31 bit data stream plus one rollover bit. The 32 bit wheel  202  generates the data stream: 11111000001110100010010101100110, which is the same pattern as the 31 bit data stream with the addition of an extra 1 at the beginning of the stream. This data stream is constant for every revolution of the clock wheel.  
         [0038]    In the 32 bit stream, no five consecutive bits are repeated anywhere else in the stream. This is true for the 31 bit data stream. When the unit is powered for movement, five consecutive (or sequential) bits are sampled from each wheel. The decimal value is calculated for each 5 bit number. The lookup table A (attached hereto) is used to convert the 5 bit number to a decimal number. Then a mathematical operation is performed on the two converted numbers (from the 31 bit wheel and the 32 bit wheel) to produce an absolute position.  
         [0039]    Referring to FIG. 7, if the unit were powered up with the wheels aligned as shown in FIG. 7, the first 5 bit data stream sampled would be: 11110 for the 31 bit wheel and 11111 for the 32 bit wheel. In the next clock cycle, after rotation of {fraction (1/32)} of the clock wheel a clock pulse is generated, the 31 bit wheel produces 11100 and the 32 bit wheel produces 11110. Continuing for 32 {fraction (1/32)} steps, or 32 5 bit frames, each sequential or consecutive 5 bit data stream produced by each wheel is unique.  
         [0040]    An example calculation is shown in FIG. 8. A 5 bit data stream is sampled from each of the 31 bit wheel and the 32 bit wheel. In this example, the 31 bit wheel produces the 5 bit data stream: 01000. The 32 bit wheel produces the 5 bit data stream 10101. These numbers convert to 08 (Lookup 1 )  21  (Lookup 2 ), respectively, using the lookup table A. 12−20=−8. If the result is negative, add 31 (Same as modulo 31 arithmetic). Apply the mathematical formula: (Result ×32)+Lookup 2 =Absolute position. This gives an absolute position of 756 out of 992 possible positions along the path of travel.  
         [0041]    The calculation of absolute position is performed in two interrupt routines by the controller. The first interrupt routine samples the clock and data wheels and generates the next bit to be used in the sliding window or sliding 5 bit data stream. When the clock wheel generates a digital low pulse, the controller executes the absolute position routine, shown in FIG. 9. Referring to FIG. 9, at step  300 , the routine checks if the IR sensor and detector are operational. If the IR sensor and detector are not operational, the controller leaves the routine at step  318 . If the IR sensor and detector are operational, the routine checks if the motor is on at step  302 . If not, the routine exits at step  318 . If the motor is on, the routine checks at step  304  if the clock pulse is going low, indicating the beginning of a clock pulse. If not, the routine exits at step  318 .  
         [0042]    If the clock pulse is aging low, the routine sets the state of the 31 bit wheel (WHEEL_ 31 _STATE) register and the state of the 32 bit wheel state (WHEEL_ 32 _STATE) register low in step  306 . These registers store the value of the next detected data bit. At step  308 , the routine checks if the 31 bit wheel stream is high. If yes, it sets the 31 bit state register to high in step  310 . If not, it continues to block  312  where it checks if the 32 bit wheel stream is high. If yes, it sets the 32 bit wheel state register to high at step  314 . If not, it calls the RPM routine, then leaves the routine at step  318 . The RPM routine takes the current bit and uses it to create the next 5 bit data stream for use in calculating the absolute position of the shutter.  
         [0043]    Once the 5 bit streams are computed and stored, the controller computes the absolute position as described above and uses that information to keep track of where the door or shutter is at each clock cycle and as a validity check for direction of movement. It should be noted that if the awning, door or shutter is moved manually, movement of the door or shutter will drive the pinions moving the clock wheel and 31 bit wheel and 32 bit wheel, so door/shutter position is always mechanically recorded in the absolute position detector assembly, ready for reading when the unit is powered on.  
         [0044]    After the current bit from each wheel is stored in the appropriate register, the RPM routine is called. Referring to FIG. 10, at step  340 , the routine checks for the direction of travel. This information is typically provided by the user input when the user selects the up button or down button. As noted above, this information can be verified changed if the absolute position information does not check out between successive clock pulses.  
         [0045]    If the shutter is moving up the routine branches to step  344 . If the shutter is moving down, the routine branches to step  342 . Each step  342  and  344  forms the appropriate sliding window (determines the consecutive 5 bits to be used in calculating the shutter position). In step  344  the routine shifts the MASK_ 31  bits left. The MASK_ 31  bit mask is a window of all 31 bits the 31 bit wheel. Then the least significant bit of the MASK_ 31  is logically OR&#39;d with the 31 bit wheel state register. Only the first 5 bits of the MASK_ 31  mask (which contains the entire 31 bit data stream represented on the 31 bit wheel) are masked. Then the MASK_ 32  bit mask (which contains the entire 32 bit data stream represented on the 32 bit wheel) is shifted left one bit and the least significant bit of the MASK_ 32  bit mask is logically OR&#39;d with the value in the 32 bit wheel state register. Only the first 5 bits are masked. This gives two shifted 5 bit data streams, one each from the 31 bit wheel and the 32 bit wheel, which are used to determine the position of the shutter for that clock cycle.  
         [0046]    In step  342  the routine shifts the MASK — 31 bits right. Then the 5th least significant bit of the MASK_ 31  is logically OR&#39;d with the WHEEL_ 31 _STATE register. Then only the first five least significant bits of the MASK_ 31  are masked. The MASK_ 32  mask is shifted one bit right. Then the MASK_ 32  mask is logically OR&#39;d with the WHEEL_ 32 _STATE register.  
         [0047]    In step  346  the routine uses a ROM lookup table (see Table A) to get a conversion for the numbers in MASK_ 31  and MASK_ 32 . These digital numbers are stored in the variables MASK_ 31 _VALUE and MASK_ 32 _VALUE. In step  348 , the difference between MASK_ 31 _VALUE and MASK_ 32 _VALUE is calculated and the remainder from modulo 31 arithmetic calculated. This result is called the DIFFERENCE. In step  350  the DIFFERENCE is multiplied by 32. Then MASK_ 32 _VALUE is added to the product. This number is the absolute position and is stored in the POS_CNTR. At step  354  the routine ends.  
         [0048]    The controller uses the POS_CNTR value in controlling the operation of the shutter in its other routines, which are not described.  
         [0049]    A schematic of the control circuit located on control board  142  is shown in FIG. 11. Controller  500  operates the various software routines which operate the rolling shutter operator  120 . Controller  500  may be a Z86733 microprocessor. In this particular embodiment, the rolling shutter is controlled only by a wall-mounted or unit-mounted switch coupled via connector J 2 . Connector J 2  has inputs for up switched hot and down switched hot. In a rolling shutter, the motor moves only when the user presses the power direction switch connected to connector J 2  and the Triac Q 1  is activated by the microcontroller. Pressing the up or down switch applies power to the board via connector J 2  and provides various motor phase and direction information to the controller  500 . When the controller  500  permits travel, Triac Q 1  enables the motor&#39;s neutral path. The motor winding, which is then powered, well conduct current.  
         [0050]    However, the control circuit can be modified to include a receiver so that the rolling shutter can be commanded from a remote transmitter (as described above). Power supply circuit  190  converts AC line power from connector J 2  into plus 5 volts to drive the logic circuits and plus 16 volts for a voltage supply to the phototransistors Q 4 , Q 5 , Q 6 .  
         [0051]    Upon receipt of a rolling shutter movement command signal through J 2 , the motor is activated. Feedback information from the motor and AC power is provided from J 1  and applied to U 3 :A, U 3 :B, U 3 :C and U 3 :D. The outputs from U 3 :B and U 3 :D provide up and down phase information to pins P 26  and P 25  respectively. The outputs from U 3 :A and U 3 :C provide up and down direction to pins P 21  and P 20 , respectively.  
         [0052]    Crystal CR 1  provides an internal clock signal for the microprocessor  500 . EEPROM 200 stores the information such as limit flags, force flats, learn mode flags, etc. The IR signal break from clock wheel  206  drives Q 5  which provides an input to signal P 31 . Wheel  31  drives Q 4  which provides an input signal to P 30 . Wheel  32  drives Q 3  which provides an input signal to P 33 .  
         [0053]    Table A attached hereto is the lookup table described above.  
         [0054]    Exhibit A (pages A1-A21) attached hereto include a source listing of a series of routines used to operate a movable barrier operator in accordance with the present invention.  
         [0055]    As will be appreciated from studying the description and appended drawings, he present invention may be directed to operator systems for movable barriers of many types, such as fences, gates, shutters, awnings, garage doors, overhead doors and the like.  
         [0056]    While there have been illustrated and described particular embodiments of the 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 invention.