Patent Publication Number: US-8113263-B2

Title: Barrier operator with magnetic position sensor

Description:
BACKGROUND OF THE INVENTION 
     Movable barriers, such as upward acting sectional doors, flexible rollup doors, and gates, for example, are typically characterized by operators which include various types of position sensors for use in controlling the barrier and for shutting off the operator motor when the barrier reaches a closed or open limit position, for example. Various types of position sensors have been developed, including mechanical limit switches, optical sensors and electrical devices, such as potentiometers. However, certain prior art barrier operator position sensors lack precision, are subject to mechanical or electrical errors and may require external wiring and devices which are costly to fabricate and install and increase the risk of malfunction of the operator. 
     Accordingly, there has been a continuing desire and need to provide barrier operators with barrier position sensors which are more reliable, versatile, accurate and less expensive than known types of sensors. It is to these ends that the present invention has been developed. 
     SUMMARY OF THE INVENTION 
     The present invention provides a barrier operator, such as a garage door, industrial door, or gate operator, including a controller operable in conjunction with an improved position sensor for determining the position of the barrier for certain purposes, including controlling the operator motor, for example. 
     In accordance with one aspect of the present invention, a barrier operator is provided with a controller which includes a magnetic position sensor which utilizes a rotating magnetic field to provide an output signal indicating, with precision, the position of the magnetic field and a mechanical element associated therewith. In particular, the operator controller utilizes a travel limit or position sensor which may be associated with a rotatable shaft which, in turn, is associated with or is part of the operator mechanism. The sensor utilizes one or more magnets attached to a shaft, preferably at one end thereof, and disposed in proximity to a two axis Hall effect sensor integrated circuit. The magnet is oriented so that its poles generate a magnetic field parallel to the surface of the circuit, but not in contact therewith. The Hall effect sensors are capable of providing output signals which are directly proportional to the position of the rotating shaft and, hence, the position of a barrier operably connected to the rotating shaft. The angular position of the rotating shaft can be measured by the sensor over a full 360° or one revolution of shaft rotation or more than one full revolution. 
     Moreover, power may be removed from the controller circuitry and reapplied without loss of a signal associated with the correct position of the shaft. A microcontroller associated with the Hall effect sensors is operable to perform calculations to determine the angular position of the magnetic field and the associated shaft. Data provided by the controller circuitry can include, but is not limited to, absolute position of the barrier, notification of arrival of the barrier at a previously learned position, namely an open or closed travel limit, direction of barrier travel and speed of travel of the barrier being controlled by the operator. 
     The invention further contemplates the provision of a door operator controller which includes a magnetic position sensor which may be directly connected to a shaft, such as an output shaft of the door operator or an auxiliary shaft operably connected to the output shaft, whereby a substantially direct reading of door or barrier position may be provided. The magnetic sensor is compact, may be mounted unobtrusively on the operator structure and is reliable in operation. 
     Those skilled in the art will further appreciate the above-mentioned advantages and superior features of the invention, together with other important aspects thereof, upon reading the detailed description which follows in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevation view, partially sectioned, of an upward acting sectional door connected to an operator which includes a magnetic sensor associated with an operator controller in accordance with the invention; 
         FIG. 2  is a detail plan view taken generally from the line  2 - 2  of  FIG. 1 ; 
         FIG. 3  is a perspective view of a magnetic barrier position sensor in accordance with invention; 
         FIG. 4  is a detail perspective view of a major part of the magnetic position sensor; 
         FIG. 5  is a block diagram of a control system for the operator shown in  FIGS. 1 and 2  and including a magnetic position sensor in accordance with the invention; 
         FIGS. 6A and 6B  are flow diagrams illustrating major steps in a process of operation of an operator in accordance with the invention; and 
         FIG. 7  is a perspective view of an alternate embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In the description which follows like elements are marked throughout the specification and drawing with the same reference numerals, respectively. The drawing figures are not necessarily to scale and certain elements may be shown in generalized, schematic or block diagram form in the interest of clarity and conciseness. 
     Referring to  FIG. 1  there is illustrated a movable barrier  10 , which may comprise a sectional or one piece upward acting garage door, movable between a closed position shown covering an opening  12  in a structure  14 , to an open position along spaced apart guide tracks  16 , one shown, in a known manner. The exemplary barrier  10  is connected to a motor driven operator  18  suitably supported by and disposed within structure  14  and connected to an elongated trolley support beam  20 , also at least partially, supported by structure  14 . Support beam  20  is adapted to support a trolley  22  for traversal therealong in a known manner to move the barrier  10  between open and closed positions. For example, the trolley  22  is illustrated as including a slide  23  connected to an elongated drive chain  24  trained over a rotatable idler sprocket  26  disposed at one end of the beam  20  and also trained over a drive sprocket  28 , see  FIG. 2  also. Drive sprocket  28  is mounted on and rotatable with an output shaft  30  supported on a frame  32  of operator  18 . Opposite ends of the chain  24  are connected to trolley slide  23  in a conventional manner known to those skilled in the art. 
     Referring to  FIGS. 1 and 2 , the operator  18  includes an electric drive motor  34  mounted on frame  32  and characterized by a rotatable output shaft  36  having a drive pulley  38  mounted thereon for driving an endless belt  40 , which belt is also trained over a pulley  42 . Pulley  42  is mounted on and for rotation with a rotatable idler shaft  44  supported on frame  32 , which shaft is also drivingly connected to a sprocket  46  interconnected with output shaft  30  by way of an endless chain  48  driving a sprocket  50  secured for rotation with shaft  30 . Operator  18  is exemplary of several types of operators which include a drive motor, one or more idler shafts for reducing or increasing the speed of an output shaft, and wherein such output shaft may be connected to a further drive mechanism, such as illustrated and described herein, or connected directly to a drum or roller, for example, for a flexible rollup type door, or to a swing arm for a swing gate, both not shown. Such an output shaft, as described above, may also be connected to a so-called jackshaft for raising and lowering sectional or so-called one piece doors. In all events, the operator  18 , and equivalents, typically includes at least one rotatable shaft, the rotation and the position of which is correlatable with the movement and position of a barrier, such as the barrier  10 . 
     In one preferred embodiment of the present invention, the output shaft  30  is provided with a distal end part  30   a , see  FIG. 3  also, which may be part of a gear type speed change mechanism  52  forming part of a magnetic position and speed sensor unit, generally designated by numeral  54 . Sensor unit  54  is characterized by a generally rectangular boxlike speed change mechanism housing  56  mounted on a wall part  32   a  of operator frame  32  and enclosing a speed reduction or speed change mechanism for reducing the output speed of shaft  30  to a desired speed and rotational limits between the limits of rotation of the shaft  30  when moving the barrier  10  from a fully closed position, shown in  FIG. 1 , to a fully open position. 
     As shown in  FIG. 3 , shaft part  30   a , by way of example, supports a pinion  58  meshed with a gear  60  supported on a rotatable idler shaft  62  which also supports a pinion  64  meshed with a gear  66  supported on and rotatable with a sensor shaft  68 , see  FIG. 4  also. Shaft  68  supports a generally cylindrical magnet  70  at one end thereof, said magnet having pole pieces  72  (N) and  74  (S). Shafts  62  and  68  are suitably supported within and by housing  56  for rotation therein. Magnet  70  comprises part of a magnetic position sensor  71 ,  FIGS. 3 and 4 , which sensor also includes an integrated sensor circuit  76 . Magnet  70  is disposed in proximity to integrated sensor circuit  76 , see  FIGS. 3 and 4 , which is mounted on a suitable circuit substrate  78  which, in turn, is preferably mounted on brackets  77  supported on a wall  79  of a cover part  57  of the enclosure or housing  56 . Cover  57  is shown as a transparent member, a substantial portion of which is broken away in  FIG. 3  for purposes of illustration. Cover  57  is adapted to be removably mounted on housing  56  in a conventional manner. Accordingly, the sensor circuit  76  is mounted in close proximity to the magnet  70  and within a rotatable magnetic field generated by the magnet and the circuit  76  is responsive to rotation of such field. The sensor circuit  76  may be of a type commercially available, such as a Model 2SA-10 manufactured by Sentron AG, Zug, Switzerland. Alternatively, the sensor circuit  76  may also be a type manufactured by Austria Microsystems, AG, Premstatten, Austria, as a type AS5045 Magnetic Rotary Encoder. 
     The embodiments of the magnetic sensor circuit  76  comprise a two axis Hall effect sensor which is operable to detect the absolute angular position of the magnet  70  as it rotates about the axis  68   a  of shaft  68 ,  FIG. 4 , which rotation is correlated directly with rotation of output shaft  30 , movement of chain  24  and the actual position of barrier or door  10 . The substrate  78  may also support additional circuit elements of the sensor  71 , as indicated in  FIG. 5 . 
     Referring to  FIG. 5 , there is illustrated a control system  73  which includes the sensor  71 . The sensor circuit  76  of sensor  71  is in communication with a microcontroller  80  configured to preferably operate on the inter-integrated circuit bus protocol (I 2 C), which microcontroller is in communication with an operator command to stop or run signal output circuit  82 , a communication protection circuit  84  and a power supply  86 . Microcontroller  80  includes a suitable EEPROM  80   a  for data storage. Suitable programming and communication schemes, including pulse width modulation, serial streams or analog techniques may be provided to accommodate the particular sensor circuit  76  being used. Circuits  82  and  84  are also operably connected to a microcontroller  88  of a barrier operator controller  90  which may be disposed within a suitable enclosure  92  mountable on frame  32  of operator  18 ,  FIG. 1 . Controller  90  may be mounted remotely and communicate with sensor circuit  76  via radio frequency wireless methods. A calibration and control circuit  94  may be included with controller  90  or removably connectable thereto. A main power supply  96  is operable to provide low voltage power to the sensor circuitry by way of power supply  86 . Power supply circuit  96  is adapted to be included in operator controller  90  together with a motor control circuit  98  for controlling motor  34 . The controller  90  may, in many respects, be similar to the barrier operator control systems disclosed in U.S. Pat. No. 6,118,243, issued Sep. 12, 2000, and U.S. Pat. No. 6,388,412 issued May 14, 2002, both to Reed et al. and assigned to the assignee of the present invention. The subject matter of U.S. Pat. Nos. 6,118,243 and 6,388,412 is incorporated herein by reference. 
     The above-described control system  73 , including the magnetic position sensor  71 , provides several benefits in a barrier operator. Absolute barrier position determination is possible, thanks to the output signal provided by sensor circuit  76  and after treatment by microcontroller  80 . Position data is stored in memory  80   a  and may be communicated from sensor  71  to microcontroller  88  for various purposes. Door travel limits may be set by inputting signals through calibration pod  94  to microcontroller  88  and to microcontroller  80  correlating with position signals received from the position sensor circuitry. Moreover, in accordance with the invention, sensor  71  will determine or maintain information regarding barrier position if power to controller  90  is interrupted for any reason. Also, no homing or learning cycle is required after power is applied or reapplied. More precise control of the so-called safety cutout point may be provided, which point is that beyond which the barrier  10  may be driven to the closed position even though an external entrapment signal, for example, is received by the controller  90 . Furthermore, as previously mentioned, the circuitry associated with the sensor circuit  76  may also be used to measure speed of travel of the barrier  10  and any changes in speed. 
     The magnetic position sensor  71  may receive two different messages from controller  90 , periodically, such as every sixty milliseconds, via microcontrollers  80  and  88 . A general broadcast message contains a running up flag, a running down flag, an up limit active flag, a down limit active flag, a mid-stop limit active flag, a reversing flag and an operator condition code. The magnetic position sensor  71  does not respond to a general broadcast message. A normal operation message is sent to the magnetic position sensor  71  including a magnetic position sensor direction correlation flag, a set up limit flag, set down limit flag, a set mid-stop flag and a calibration request confirmation flag. The magnetic position sensor  71  interprets this information and then responds with an update message after receipt of a controller normal operation message. During the time period between messages from the controller  90 , the magnetic position sensor  71  will determine its current rotational position and rotational speed, calculate rolling averages of these values and store them for translation to the controller. These values will be continually updated until the controller&#39;s message is received and the sensor enters a reply mode. 
     The magnetic position sensor  71  is operable to receive a set limit command from the operator controller  90  wherein the set position is up, down or mid-stop. If the motor  34  of operator  18  is not running and a calibration request confirmation flag is set, the sensor  71  will store a current running average representing its current position but will not store the same position value for two different limit positions. Accordingly, if the operator controller  90  is running when the set limit command is sent or, if the current position has already been assigned to another limit, or the current position does not meet the requirements of the programmed values, the limit position will not be stored in memory but will send an unable-to-set-limit flag for the next communication cycle. If the calibration request confirmation flag is not set, the sensor  71  will ignore such request. 
     The sensor position value associated with a mid-stop limit must fall between values associated with an up and down limit position of the barrier  10 . Accordingly, both the up and down limits must be set before the mid-stop limit can be set. The sensor  71  will set the up, down and mid-stop limit set flags if position values have been stored in memory for a given limit. These flags will be cleared if no value has been stored in the associated memory locations. The position sensor  71  will set a limit sensor direction flag equal to the current rotational direction of the sensor input shaft  68 . Clockwise (CW) and counterclockwise (CCW) directions may be determined by viewing the sensor with the end of the input shaft  68  at which the magnet  70  is disposed facing the viewer. In conventional door operators determination of direction of rotation is also carried out by viewing the operator facing the operator output shaft. The comparison may be made initially between 250 and 500 milliseconds after the operator  18  begins moving the barrier  10 . If the sensor  71  determines that the operator  18  is running in the wrong direction, the sensor will activate a stop run output signal to the controller  90  and also send a running wrong direction flag for two communication cycles until the aforementioned general message indicates that the operator  18  has stopped the barrier  10 , whichever is longer. After completing this set of steps, stop run output and running wrong direction flags would be cleared. 
     It may be necessary to provide for adjustment of the gap between the sensor circuit element  76  and the magnet  70  to achieve the highest resolution signal. Such adjustment may be made by positioning the substrate  78  at selected positions on the spaced apart support bracket  77 ,  FIG. 3 . Alternatively, the position of the magnet  70  on shaft  68  may be adjusted to adjust the gap between the magnet face  70   a ,  FIG. 4 , facing the circuit element  76  and the face  76   a  of the circuit element facing the magnet. 
     When the sensor  71  indicates that the operator  18  is moving the barrier  10  in a particular direction, the sensor compares a rolling average signal (two-bytes, for example) representing the current position to a stored limit position. For example, if the operator  18  is running the barrier  10  toward a closed position, the current position of the barrier is compared to a predetermined barrier down or closed limit value. When the current position equals or exceeds the stored limit position value, the sensor  71  activates a stop run output signal and maintains it active for two communication cycles or until a broadcast message indicates that the operator  18  has achieved the desired limit position and has stopped the barrier  10 , whichever is longer. After this process, the stop run output signal is cleared. 
     If a mid-stop limit position has been set, then when the operator  18  is running the barrier  10  toward the up or open position, the sensor  71  will consider the mid-stop limit to be the up limit and activate a stop run output signal. Sensor  71  will also activate a mid-stop limit active flag and if a run on to the barrier up limit position is initiated from the mid-stop limit, the sensor  71  will then use the up limit as normal. The mid-stop limit does not affect barrier travel in the down direction. However, a mid-stop limit active flag should be set as usual, if appropriate. If a mid-stop limit position is not set, it is ignored and any associated flag is left inactive. 
     As known to those skilled in the art, barrier operators, such as the operator  18 , will not stop a barrier precisely at a given position. Accordingly, the magnetic position sensor  71  should, typically, consider a range of position values following the actual limit setpoint to be considered as an active limit setpoint. When the sensor position value is within the range set, it will set a corresponding limit active flag and the limit active flag will be cleared when the sensor current position is not within the corresponding range. All limit position values are stored in the aforementioned non-volatile memory. 
     The sensor  71  must account for crossing a zero boundary during operation. It is possible to set one limit at the extreme lower or upper limit of the measurement range and have the other limit set at the other limit of the range with normal operation crossing over a zero point of the range. This allows the limit positions to be set without regard for the position of the output shaft  68  with respect to the sensor&#39;s measurement range. 
     Referring to  FIG. 6A , there is illustrated a flow diagram indicating at least certain major steps in the overall operation of the control system  73  and the sensor  71 , in particular. Upon energization of the control system  73  at the start step  100 , the sensor  71  will be initialized at step  102  and sensor data stored in memory  80   a  will be input to microcontroller  80  for calculation of sensor and barrier position, rolling averages and rotational speed which may be correlated with velocity of the barrier, these operations indicated by steps  104  and  106 . The sensor  71  receives regular communication updates from the microcontroller  88  to determine if the operator  18  has been energized at step  108  and if so, to determine if a limit has been reached at step  110 . If the operator  18  is not running at step  108  the process continues to step  112  to determine if communication with microcontroller  88  is enabled. If such is the case, the process continues to step  114  to determine and assemble a message to the microcontroller  88 . The process then returns to step  104 , as indicated. 
     Referring further to  FIG. 6A , if at step  110  a limit position has not been reached, the microcontroller  80  queries itself for any error signals which may have been input from the magnetic sensor circuit  76  at step  116  and examines possible operator errors, including operation in the wrong direction with respect to that commanded and overrunning the operator limit positions, for example. If none are present, the process returns to step  108 . If an error signal is present at step  116 , the process proceeds to step  118  to activate a stop run output signal to be communicated to microcontroller  88 . Of course, if a limit position has been reached at step  110  the same output signal from microcontroller  80  is communicated to controller  90  to cease operation of motor  34 . 
     At step  112 , if communication with the host microcontroller  88  is not enabled, the process queries the microcontroller  80  to determine if an average barrier position has been calculated at step  120 . If not, the routine returns to step  104 , as indicated in  FIG. 6A . If an average position of the barrier has been calculated the microcontroller  80  is enabled to communicate with the microcontroller  88  at step  122  and a message is sent to microcontroller  88  at step  114 . 
       FIG. 6B  illustrates an interrupt routine, such as would be carried out as a consequence of every communication event with controller  90 . The interrupt routine is commenced with communication with microcontroller  88  at step  124  and, if communication is confirmed at step  126 , information correlating the direction of movement of the barrier with the process already programmed into the microcontrollers  88  and  80  is stored as indicated by step  128 . If a calibration command signal is received at microcontroller  80  at step  130 , calibration data is stored in the associated memories of microcontrollers  80  and  88  at step  132 . If a calibration command is not received at step  130 , the process returns to commencement of the interrupt routine. 
     As previously mentioned, the gear reduction (or increase) drive mechanism is operable to provide rotation of the magnet  70  up to 360° for the full travel of the barrier  10  between open and closed positions. In some instances, depending on the type of barrier operator, the gear speed or position change drive mechanism  52  may actually be a gear speed increase drive mechanism in order to achieve up to 360° of rotation of magnet  70  for the full range of barrier movement. Moreover, other power transmission means, such as chains or cogbelts or other positive, position for position, speed change mechanisms may be used to provide a precise relationship between barrier position and sensor  71 . If the sensor  71  is permitted to run more than 360°, that is, cause magnet  70  to rotate more than 360°, so as to “wrap around” during any operation, the magnetic sensor circuit  76  will generate a signal to the microcontroller  80  which will provide flag signals at the stop/run output circuit  82  for two communication cycles or until a message or signal indicates that the operator  18  has stopped. The stop run output signal is then cleared and a limit sensor overrun flag is cleared when the operator  18  begins another movement after coming to a complete stop in acknowledgement of the limit sensor overrun flag. However, the system  73 , including the sensor  71 , may be modified to allow for and monitor rotation of the magnet  70  through more than 360° or more than one revolution of the magnet  70  while measuring speed and travel of barrier  10 . 
     The microcontroller  80  receives data from sensor circuit  76  and its own memory  80   a  and calculates a running two-byte average of the current position and rotational speed of the shaft  68 . The sensor  71  will then enable communication with the operator controller  90  as an I 2 C slave device and will have valid data to pass to the controller at its first communication. The sensor  71  is also operable to receive calibration commands from the controller  90  indicating which limit position is associated with the current position, for example. This command is only valid if the operator  18  is not moving the barrier  10  and the calibration request confirmation flag is set. Under these circumstances, the sensor  71  will store the current limit position in a memory of the microcontroller  80  and then send an appropriate limit set flag to the operator controller  90 . If the operator  18  is still moving the barrier  10 , the sensor  71  will send an unable to set limit flag and, for a given limit position, if a particular limit is already set, the receipt of a second limit command for that limit will clear the current limit position and store a new value. Such a process allows resetting of the limit position relatively easily. If a calibration request confirmation flag is not set, the sensor  71  will ignore the calibration request. 
     The sensor circuit  76 , as mentioned previously, is mounted in proximity to the magnet  70  and the position of one or the other of these components relative to the other may be adjusted, as needed. Enclosure of these components, as described above and shown in  FIG. 3 , is important to protect the sensor and its associated circuitry. Electrical specifications may be in accordance with known practices for the manufacture and installation of electronic components. The communication protocol may be in accordance with standard I 2 C hardware, baud rates and generic data format. Transfer protocol, addresses and data formats may also be in accordance with known practices. 
     Referring briefly to  FIG. 7 , in certain applications of the control system  73 , a higher resolution or more accurate determination of barrier position may be required. Accordingly, the control system  73  may be modified as to the sensor  71  by modifying shaft  68 , as shown in  FIG. 7  and designated by the numeral  68   b , to accommodate a cylindrical member  140  supported on shaft  68   b  for rotation therewith. Member  140  supports a circumferential array of magnets  142   a ,  142   b  and  142   c  through  142   h , each magnet having opposite N and S poles, as indicated by the illustration of  FIG. 7 . A second sensor circuit  76   b  is mounted on a suitable substrate  78   b  suitably supported within housing  56  or on a modified cover similar to cover  57  to accommodate the extra length of the shaft  68   b , for example. 
     The multiple magnet sensor arrangement provided by the member  140 , the circular ring array of magnets  142   a  through  142   h  and additional sensor circuit  76   b  provides for a “fine” or precise position measurement by producing additional electrical cycles of sine and cosine signals per revolution of shaft  68   b . Accordingly, coarse information from the magnet  70 , and the sensor circuit  76  mounted directly adjacent to the magnet  70 , is used to locate which sector or magnet  142   a  through  142   h  is adjacent the second sensor circuit  76   b . The accuracy of determining the position of the barrier  10  may be improved per one 360° revolution of the shaft  68   b  with suitable electronic calibration. The “coarse” and “fine” signals from the respective sensor circuits  76  and  76   b  may be processed by the microcontroller  80  to generate an output signal with significantly improved resolution and, hence, accuracy of barrier position determination. Alternatively, the multiple magnet sensor provided by the member  140  and the sensor circuit  76   b  mounted adjacent thereto may provide improved resolution or accuracy of position of the barrier  10  without the use of the magnet  70  and the sensor circuit mounted adjacent that magnet. 
     The present invention, except as otherwise described herein, may be fabricated and operated in accordance with known practices, using commercially available components and materials. Although preferred embodiments have been described in detail herein, those skilled in the art will also recognize that various substitutions and modifications may be made without departing from the scope and spirit of the appended claims.