NZ260824A - Control system for garage door opener compares monitored operation parameter with stored values - Google Patents

Description

260 PATENTS FORM NO. 5 Fee No. 4: $260.00 PATENTS ACT 1953 COMPLETE SPECIFICATION After Provisional No: 260824 Dated; 22 June 1994 J &WRef: 10088/3 CONTROL SYSTEM /tv»' £ 1 73 J U N 7995 1 I/WE ANZTROL SYSTEMS LIMITED, a New Zealand company of 36 Alexandra Street, Howick, New Zealand hereby declare the invention for which I/We pray that a patent may be granted to me/us, and the method by which it is to be performed to be particularly described in and by the following statement: 1 2 i i 08 241 CONTROL SYSTEM technical field This invention relates to a control system.

Reference throughout the specification shall be made to use of the present 5 invention as a control system for operating garage doors. However, it should be appreciated that the present principles of the present invention can be used to operate other exit/entry devices, and indeed possibly completely different applications.

Background Art There are a number of door controllers currently available. For safety reasons, the majority of these have obstruction detection.

According to US Patent No. 4856653 the most common form of safety device is a strip at the leading edge of the door which includes a switch which is operated when it strikes an object. When the switch is activated, 15 the control system then initiates a safety operation.

US Patent No. 4335339 discloses a door controller which operates a safety function when an increase in current drawn by the motor operating the door is detected.

New Zealand Patent No. 219878 discloses a system whereby the control 20 system 'remembers' previous 'door travel characteristics'. The position of the door is tracked and this information linked with timing means is compared against the door travel characteristic. The door travel characteristic is in the form of a rolling average of previous operations of the door) located in memory. If the position of the door is not where it is 2 260824 expected in a certain time interval, then the safety function is activated.

Unfortunately, there are problems associated with each of the prior art devices discussed.

Safety strips generally only work when the door is closing, not when it is 5 rising. Further if the door caught an object during its upwards travel, then a typical safety strip would not detect this. Another problem with safety strips is they may not be positioned in the appropriate place as the obstruction may not occur on the leading edge where the safety strip is normally positioned.

A problem with detecting motor load is that the motor load can vary according to the position and weight of the doer, the door age, the track condition and climatic conditions.

While door control systems which remember past door travel characteristics can keep track of such variations as door age and track 15 condition, there are still problems associated with these.

A major problem is that a stable voltage reference and signal conditioning are required to ensure that the door travel characteristic being measured is still essentially the same as that stored despite variations in voltage which could be caused by such external factors as 20 temperature.

Signal conditioning usually requires the use of a current transformer thus adding both cost and size to the door controller.

It is an object of the present invention to address the above problems, or at least to provide the public with a useful choice. 3 260824 Further objects and advantages of the present invention will now become apparent from the following description which is given by way of example only. nTSr.T.ORTTRK OF INVENTION According to one aspect of the present invention there is provided a control system for controlling the operation of a device, the control system containing memory means which contains device operation parameters including a stored first operation parameter, sensing means which detect the operation of the device including a sensed first operation parameter, comparison means which can compare the stored first operation parameter with the sensed first operation parameter, processing means which scales the sensed operation parameters in 15 accordance with the comparison between the first stored and sensed operation parameters, and comparison means for comparing the scaled operation parameters with the stored operation parameters.

Throughout the specification, the device shall now be referred to as a 20 garage door and the control system as being a door controller It should be appreciated however that the present invention can apply to other control systems for controlling other types of devices.

Preferably the first operation parameter sensed occurs when or where a door obstruction is unlikely to occur, perhaps at the start of the door 25 opening or closing cycle. 4 260824 The door operation parameters may be any parameters associated with the operation of the door. For example, these may include the voltage, current or load on the motor operating the door, the door position, the door speed or timing, the sound that the door makes, temperature of a 5 particular component and so forth.

For ease of reference, a preferred embodiment will be discussed in which the door operation parameters shall be referred to as the relationship between the current load on the motor operating the door and the door position. It should be appreciated that other parameters may apply.

In a typical door operation, the load or load by the motor operating the door changes with the door position. A graph of motor load versus door position can be derived by averaging repeated measurements being made of load and position during multiple opening and closing of a door with a particular motor. This plot shall be referred to as a pre-defined curve.

The applicant has found that the actual shape of the curve is substantially the same for each door position. However, when the curve is graphed on a motor load versus door position axes, the starting point of the curve may vary with each situation. This variation of starting point may be due to changes of temperature, humidity, condition of the motor 20 or any number of various parameters. As discussed, the starting point has been in the past compensated to a limited extent by the use of a rolling average of each door travel. This does not compensate for significant changes due to wind force, humidity, temperature, supply power or any other fluctuations that may occur from one operation to the 25 next. 260824 The present invention addresses the above problem by introducing a scaling factor (which may be multiplicative, additive, subtractive or otherwise) depending on the difference between the sensed first operation parameter and the stored first operation parameter.

As an example, the stored first operation parameter may be a certain voltage/current associated with the first door position. In operation, the current sensed for that first door position may vary, for example it may be higher by 20 mA. In this example, the fact is that it led to the sensed first operation parameter being higher by 20 mA may also cause the cuiTent 10 associated with other door positions to also be higher than 20 mA -f the operation of the door is normal. Therefore, the present invention treats the door operation as a 'floating' pre-defined curve and effectively brings the sensed curve down to the stored curve for comparison by appropriate scaling (say by subtracting 20 millivolts from each reading).

It should be appreciated that the scaling relationship required to be performed before the sensed parameters can be compared with the stored parameters may not be merely the difference between the first operation parameters. Instead, the scaling relationship may only be determined by the difference between the first operation parameters which can be a 20 variable in a suitable function.

In preferred embodiments of the present invention the stored curve is associated with safety threshold limits. For example, for a specific door position, there may be a range of permissible scaled load parameters which do not trigger a safety operation. Anything outside these limits 25 will be considered an obstruction by the control system and the appropriate safety operation implemented. 6 260824 As should be appreciated, the methods of determining door obstruction may vary.

For example in one embodiment the parameter measured may be motor current. Following a short delay to ignore in-rush current, slow and fast 5 rolling current averages may be established. During the door travel, the slow and fast rolling averages may be updated following each new current reading (say 100 or 120 times per second). After an update, the slow rolling average may be adjusted with a stored value based on travel direction and then door position and then compared with the fast rolling 10 average. If the difference is greater than pre-set limits (such as a safety threshold) it is then deemed to be a door obstruction condition.

As can be appreciated, the above method of determining a door obstruction is looking at the rate of current change and does not depend on absolute current readings. This avoids problems associated with 15 temperature and component drift and simplifies the circuitry required for current measurement. Also, the influence of long term motor and mechanical load variations that are independent of door position are minimised in assessing obstructions.

Essentially, the above example uses the present invention by establishing 20 a new slow average or reference value each time the motor is turned on.

In preferred embodiments, the values used in adjustment to the slow rolling averages may be established during the installation cycle. Storing adjustment (offset) values may give a large dynamic range with minimum memory requirement.

There may be a number of ways by which the operation parameters can be measured. One method by which current can be measured is 7 260824 discussed below.

An electrically isolated current measurement method (such as that used by optical devices) may be used which is based on using a low resistance in series with a motor. An optical isolator circuit in parallel with this 5 low resistance may give an isolated output proportional to the motor current. This isolator signal may then be amplified and then rectified into two separate signals. One signal may then be filtered and further amplified for use by the analogue input of the control system. The other signal may be used for peak detection to initiate the analogue sampling by 10 the control system.

It should be appreciated that the signal does not need to be absolute and therefore temperature and optical isolator drift compensation or an accurate voltage reference are not required.

In some embodiments of the present invention there may be provided an 15 overload protection whereby the motor is shut down if the load on same is above a certain limit. This may be independent of obstruction detection.

According to an alternate aspect of the present invention there is provided a control system for a operation of a door characterised in that the control system is capable of holding the door at a position between 20 fully closed and fully opened.

The ability to have a garage door (or other type of door) held in an intermediate position can be useful in situations where security or restricted vision is still required, but also ventilation or pet entry as well. In some embodiments of the present invention there may be a number of 25 possible intermediate positions set. Also, the actual gap size may be programmable by the user of the control system. 8 260824 In some embodiments of the present invention, the controller may be user programmable from a remote code transmitter. In preferred embodiments of the present invention the codes are set at the door controller rather than on the transmitter. This provides considerable 5 security advantages.

In one embodiment of the present invention, multiple codes may be programmed and stored by the controller which is a significant advantage over traditional controllers which only have a dipswitch to set a single code.

Some examples of possible actions which can be taken on receiving a valid code from a transmitter are given below.

CODES 1 ACTION DESCRIPTION Change If last travel was down then open, else close 2 Cycle Open, then wait preset time and close 3 Intermediate Move door to preset intermediate point 4 Aux 1 Turn auxiliary 1 output on for preset time Aux 2 Turn auxiliary 2 output on for preset time Various operations of the control system may use a timer. These timer values may in some embodiments of the present invention be user programmable. One example in which time periods can be user programmable is given below. 9 *60824 ACTION DESCRIPTION Light The light time sets how long the courtesy light remains on following a door travel command Cycle Sets the time delay before closing when the door cycle action is in progress Aux 1 Sets the auxiliary 1 on time to be used when an auxiliary 1 output is initiated Aux 2 Sets the auxiliary 2 on time to be used when an auxiliary 2 output is initiated Brief Description of Drawings Aspects of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure la is a graphical representation of a stored load deviation curve, and Figure lb is a graphical representation of a sensed load deviation curve, and Figure lc is a graphical representation of scaled load deviation curve.

Best Modes for Carrying out the invention With respect to Figure la, there is illustrated in graphical form a typical representation of a load deviation curve which may be stored in a control system in accordance with the present invention. 2608 In Figure la, the axes shown are that of current versus door position. The solid line 1 represents an average current load on the motor moving the door in relation to door position. The shaded area 2 represents a preset safety limit inside of which the door is operating in normal mode.

Figure lb illustrates in graphical form a sensed load deviation curve indicated by solid line 3. The starting point or first operation parameter 5 for the line 3 is a distance A above the first stored operation parameter or starting point 6 of the curve 1.

In Figure lc, the difference A between the starting points 5 and 6 has been used as an offset to bring down the sensed line 3 for comparison with the stored line one. As can be seen the starting points 5 and 6 are now identical, although for the most part the line 3 is slightly different than the line 2. Nevertheless, the most of the line 3 still falls within the safety limits represented by shading 2 and thus this difference is not construed as a door obstruction.

An exception to the above is the peak 7. Although line 3 has been scaled downwards by an offset A, the peak 7 still falls outside the limits 2. Thus, this peak 7 represents an obstruction and will trigger an appropriate safety operation by the controller.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof of the appended claims. 11 260824

Claims (5)

WHAT WE CLAIM IS:

1. A control system for controlling the operation of a device, the control system containing memory means which contains device operation parameters 5 including a stored first operation parameter, sensing means which detect the operation of the device including a sensed first operation parameter, comparison means which can compare the stored first operation parameter with the sensed first operation parameter, 10 processing means which scales the sensed operation parameter in accordance with the comparison between the first stored and sensed operational parameter, and comparison means for comparing the scaled operation parameters with the stored operation parameters. 15

2. A control system as claimed in claim 1 wherein the device is a garage door and the control system is a door controller.

3. A control system as claimed in claim 2 wherein the first operation parameter sensed occurs when or where a door obstruction is unlikely to occur. 20

4. A control system as claimed in either claim 2 or claim 3 wherein one of the door operation parameters is the current load on a motor operating the door.

5. A control system as claimed in any one of claims 2 to 4 wherein a further door operation parameter is the door position. 12 NEW ZEALAND 1 PATENT OFFICE 31 JAN 1997 RECEIVED 2608 A control system as claimed in any one of claims 1 to 5 wherein the device operation parameters contained in the memory means form a curve. A control system as claimed in claim 6 wherein the sensed operation parameter is treated as a floating curve capable of being scaled to match a stored curve. A control system as claimed in any one of claims 1 to 7 which includes safety threshold limits. A control system as claimed in any one of claims 2 to 8 characterised in that the control system is capable of holding the door at a position between fully closed and fully opened. A control systeta as claimed in any one of claims 1 to 9 wherein the control system is user programmable from a code received from a remote code transmitter. A control system substantially as herein described with reference to and as illustrated by the accompanying drawings. ANZTROL SYSTEMS LIMITED by its Attorneys JAMES & WELLS NEW ZEALAND PATENT OFFICE 14 FEB 1997 RECEIVED , 13