WO1995008858A2

WO1995008858A2 - Monitoring apparatus

Info

Publication number: WO1995008858A2
Application number: PCT/GB1994/002045
Authority: WO
Inventors: Bruce Stanley Gunton
Original assignee: Bruce Stanley Gunton
Priority date: 1993-09-24
Filing date: 1994-09-21
Publication date: 1995-03-30
Also published as: AU7661194A; GB2287369A; GB2287369B; GB9510565D0; WO1995008858A3

Abstract

Apparatus is described for monitoring variations in a parameter such as a varying voltage level. Two signals (30, 40) are created from the varying voltage level. The signal (30) may track the varying voltage with negligible delay, but the signal (40) is created with a larger time constant. Consequently, if the voltage rises suddenly, the voltage (30) will rise more rapidly than the voltage (40) until the two profiles cross. Monitoring the difference between the signals (30, 40) thus allows sudden changes in the voltage to be detected. The technique has many applications such as detecting rises in motor current for an automatic door, arising from the presence of an obstruction.

Description

Monitoring Apparatus

The present invention relates to monitoring apparatus and particularly, but not exclusively, to apparatus for monitoring the movement of movable members such as doors.

It is known to provide motors for moving garage doors, factory doors, security grilles and the like. For instance, the driver may keep an infra red or radio device in a vehicle to allow the motor to be activated as the vehicle approaches the garage door, so that the door can be opened and the vehicle driven into the garage without the driver leaving the vehicle.

Various safety problems arise, particularly when motors are fitted to doors in domestic premises. Apparatus must be safe in the presence of unskilled people and children. Complicated installation is likely to make adequate safety more difficult to achieve but the wide variety of situations in which such a system might be installed tends to complicate installation procedures for known apparatus.

The present invention seeks to obviate or mitigate these and other disadvantages.

The invention provides monitoring apparatus for monitoring variations in a parameter, comprising means operable to provide first and second signals which vary in response to variations of the parameter being monitored, comparison means operable to compare the first and second signals, and time constant means operable to provide time constants which govern the responses of the signal generating means, the time constant means causing the second signal to be governed by a longer time constant than the first, whereby the comparison result will vary in accordance with the rate of change of the parameter.

The first time constant means is preferably operable to pass the said level to the comparison means after a delay governed by a first time constant.

The first and second signals are preferably derived from the voltage or current level at a common point. The said voltage or current level is preferably directly derived from the parameter being monitored.

The apparatus may further comprise intermediate means operable to derive an intermediate signal from which the second signal is derived, the intermediate means providing a signal level governed by the signal levels at the common point and at a reference point. The intermediate means preferably comprises a potential divider tapped to provide the intermediate signal. Preferably second time constant means are operable to pass the intermediate signal to the comparison means after a delay governed by the second time constant.

Preferably at least one time constant means comprises a capacitance and resistance in series.

Control means may be provided, operable to change one or both time constants to modify the responses during periods in which the rate of change is expected to be substantially different to the rate outside the period.

The comparison means is preferably operable to provide a voltage or current comparison. Alternatively, the comparator may encode the first and second signals as digital signals and make a digital comparison thereof. Alternatively, the comparison means may create first and second comparison signals at frequencies which depend on the levels of the first and second signals, and compare the frequencies of the comparison signals.

Preferably alarm means are provided to recognise an alarm condition in response to a predetermined output or range of outputs of the comparison means. The parameter monitored may be the torque of a motor, and the first and second signals are preferably derived from motor current. The parameter being monitored may be the noise level in an environment.

In another aspect, the invention provides a control system for automatically moving a movable member between first and second positions, comprising lock means operable to lock the movable member in at least one of the positions, and means operable to release the lock means, if locked, when the control system is correctly instructed to move the member, and to engage the lock means when the member reaches the other of the said positions .

In a third aspect, there is provided control apparatus for a movable member, comprising switch means, detector means operable to detect operations of the switch means, and control means operable to select a function to be performed by the control apparatus, the function being selected in accordance with the detected sequence of operations.

Preferably a first detectable sequence authorises the opening or closing of the closable member. A second detectable sequence may authorise the illumination of a light source. A third detectable sequence may authorise disabling of the control apparatus. Disabling may be for a predetermined time or until a further authorising sequence is detected. The third sequence may be repeated actuation in excess of a predetermined number within a second set period of time.

A fourth detectable sequence may authorise the programming of the control apparatus to receive instructions from a remote control device.

A fourth aspect provides control apparatus for a movable member, comprising counter means operable to count operations of the apparatus and to disable the apparatus after a predetermined count is reached.

A fifth aspect provides a security system comprising a movable member, an electric motor for controlling the position of the movable member, and a back-up battery operable to supply the motor in the absence of an external supply. The electric motor is preferably a low voltage DC motor. There may be charging means for charging the battery from an external supply.

A sixth aspect provides a security system comprising a movable member, an electric motor for controlling the position of the movable member, means operable to short the motor coils when not in use, and means providing a permanent drive linkage between the movable member and the motor.

A seventh aspect provides control apparatus for a movable member, comprising speed selection means operable to change the speed at which the movable member is driven, and to provide a reduced speed as the member approaches a predetermined position.

An eighth aspect provides control apparatus for a movable member, comprising sound detection means operable to detect sudden sounds significantly above ambient levels, and means operable to stop the movable member from moving when a sound as aforesaid is detected.

The sound detection means may incorporate monitoring apparatus in accordance with the first aspect of the invention.

A ninth aspect provides control apparatus for a movable member, drive means operable to drive the movable member, and monitoring apparatus in accordance with the first aspect. The monitoring apparatus is preferably operable to monitor the load on the drive means and to stop the drive means when an abnormal load is detected.

The monitoring apparatus may monitor ambient noise levels, and stop the drive means when an abnormal level is detected.

The apparatus may incorporate apparatus according to any or all of the second to the eighth aspects of the invention .

The apparatus may be operable to stop when an obstruction is detected while the movable member is moving. The apparatus may cause the movable member to reopen when an obstruction is detected while the movable member is moving. The movable member may reopen only if the obstruction is detected during a first part of the moving phase, the member being merely stopped if the movable member is at or near an end position of the movement .

Embodiments of the present invention will now be described in more detail, by way of example only, and with reference to the accompanying drawings, in which: Fig. 1 shows a motor load current profile for a typical application of an electric motor for controlling a garage door, annotated with reference to a first detection technique;

Fig. 2 corresponds to Fig. 1 and is annotated with reference to a technique according to the present invention ;

Fig. 3 is a part schematic diagram of monitoring apparatus in accordance with the invention.

The following examples will be explained in rela¬ tion to garage doors, particularly those which are lifted to open them, and which are stowed in their open position in the roof of the garage. However, it will be readily apparent to the skilled man how the techniques described can be modified to suit other situations, such as garage doors which move horizontally, or other types of closable member, such as industrial doors, or movable members.

Fig. 1 shows a typical motor current profile for an electric motor driving a garage door from the closed position (at the left of Fig. 1) toward the open position. The motor current is related to the load on the motor. Initially, the current profile 10 rises to a high peak 12, partly because of the inertia of the door. Current then begins to drop at 14 and subsequently rises and falls as the load on the motor varies. Variations can be caused by local stiffness in tracks along which doors are moving, changes in the angle at which the door is moving (which changes the degree to which the motor must overcome gravity) and other factors, including the tension of springs etc.

A rising slope at 16 indicates what happens if the door is obstructed. The motor current will rise to a very high value (not shown) as the motor continues to attempt to drive the door past the obstruction. A similar peak will also occur when the door reaches either end of its range of movement. An obstruction could be caused by a vehicle incorrectly positioned, for instance, or could be caused by part of a human body becoming trapped in or by the mechanism, such as a child's hand being trapped. It is important to be able to sense obstructions to avoid irreparable damage or injury.

Fig. 1 indicates one way in which this problem could be addressed. A reference level 18 indicates a reference current which is above the level of any current normally expected, except the peak 12. Consequently, an obstruction can be assumed to exist when the profile 10 rises above the level 18. It is necessary to ignore the initial surge 12 and the arrangement could therefore have a time delay built in so that the current must remain above the reference level 18 for a short set time before action is taken. Secondly, the reference level 18 must be sufficiently high to avoid false triggering during normal operation. Thus, the level must be above any expected level, with the exception of short surges, but including any higher level which might arise as a result, for instance, of extra wind pressure on a windy day. Broken profile 20 indicates the current profile which might apply when additional wind pressure bears on the door. It can be seen that in order to provide reliable operation even when wind is at the maximum likely to be encountered, the level 18 is considerably above the highest level of profile 10 (other than the peak 12). This, together with the delayed response, means that if an obstruction is encountered when the current is relatively low, such as the trough 22, the current must rise a long way up the slope 16 before reaching the reference level and may continue to rise thereafter until the response delay has elapsed. There is thus the potential for applying considerable power to force the door past the obstruction, with consequent risk of damage or injury . Fig. 2 corresponds to Fig. 1 but indicates an alternative arrangement, in accordance with the invention .

The profile 30 is essentially the same as the profile 10, having an initial peak 32 followed by a drop 34, and a rising slope 36 after an obstruction arises at a trough 38. An important difference in Fig. 2 concerns the reference level 40, which is not constant. The level 40 is initially very high (so that any initial peak 32 does not rise above it) and then falls until reaching a level slightly above the profile 30. This situation exists part way down the drop 34. Thereafter, the reference level follows the profile 30, rising and falling with it, in a manner which will be described below. The level 40 remains just above the profile 30 during the relatively slow rises and falls, until the trough 38 is reached. At that point, the profile 30 begins to rise rapidly. The level 40 is constrained from rising as rapidly as the profile 30, in a manner to be described below. Consequently, the profile 30 quickly meets and then exceeds the reference level resulting in an alarm condition being recognised and appropriate action taken. It can be seen by comparison of Figs. 1 and 2 that in the arrangement of Fig. 2, there is a shorter delay between the obstruction arising at 38 and the threshold being exceeded at 42, and the power applied to the door is relatively low after the obstruction has been encountered. This reduces or eliminates the danger of damage or injury.

A reference level 40 which tracks a profile 30 in the manner just described can be achieved in various ways. One example of apparatus for achieving this is illustrated in more detail in Fig. 3.

Fig. 3 shows an electric motor 50 whose windings are connected between switches 52A,52B. The motor 50 is a low voltage DC motor powered from a battery 54 (or accumulator or other DC supply) whose positive voltage appears at the upper terminals (as shown in Fig. 3) of the switches 52. The lower terminals of the switches 52 are connected through series resistor R1 to the other pole of the battery 54. The motor can open or close a door (marked DOOR) through a linkage shown schematically in Fig . 3.

This circuit is tapped at 56 to provide a voltage at point A which is a measure of the motor current. Consequently, the voltage at A will rise and fall with motor current, following a profile of the same shape as the profile 30. Point A is the input to a circuit indicated generally at 58, and which provides first and second signals which vary in response to variations of the voltage A (and hence the motor current), and are provided for comparison by a differential amplifier 60 (acting as a comparator). Time constants govern the responses of the signal generating means and provide a longer time constant for the second signal than for the first. Thus, the difference between the first and second signals will vary in accordance with the rate of change of the motor current.

In more detail, the voltage A is applied to a series resistor and capacitor R2,C1 to provide a voltage at point A' which follows the voltage at A, but subject to the time constant (R2xC1). This time constant is made very small in relation to other aspects of operation, particularly expected rates of change of the profile 30 during normal use. For instance, the time constant R2,C1 may be of the order of 50 ms. Thus, the voltage at A' follows the voltage at A with negligible delay. The voltage at A' is applied to the positive terminal of the amplifier 60 through a resistor R3. (It is to be understood that any practical system will have some form of time constant or response time, even if negligible, and that in many situations, it may be preferable for the first time constant to be negligibly small). R2 and C1 also provide a filtering effect to filter out motor noise and radio interference.

An intermediate voltage is provided at B by a potential divider formed by series resistors R6 and R7 connected between A and V⁺. Thus, the voltage at B will rise and fall with the voltage at A (and thus with motor current) but remain above it. This intermediate voltage is applied to a second series resistor and capacitor R8,C3 to provide a voltage at B' which rises and falls with B, but is subject to the time constant (R8xC3). The derived voltage B' is provided to the negative input of the amplifier 60, to allow a comparison with the voltage A¹ .

The time constant (R8xC3) is very high in comparison with time constant (R2xC1). For instance, time constant (R8xC3) may be of the order of 1 second. However, the time constant (R8xC3) is still relatively low in comparison with rates of change of the profile 30 during normal use.

Thus, in normal use, after initial transients have died down as will be described below, the voltage at A rises and falls with the motor current, these changes being relatively slow. The very short time constant (R2xC1) causes the voltage at A' and the positive input of the amplifier 60 to follow this voltage with negligible delay. The positive input of the amplifier 60 therefore receives a signal equivalent to the profile 30. The voltage at B is held above the voltage at A, rising and falling with it but remaining slightly above it. This tracking voltage is passed through to the negative input of the amplifier 60. Since time constant (R8xC3) is relatively fast in comparison with normal variations at A, the negative input corresponds to the reference level 40 of Fig. 2.

If the motor current rises abnormally quickly, as will occur when an obstruction is met, the voltage at A will rise rapidly as will the voltage A' at the positive input of the amplifier 60. This is because of the short time constant (R2xC1). The voltage at B will also rise rapidly, but the voltage at B' is prevented from rising so rapidly by the time constant (R8xC3). In consequence, the profile 30 rises more rapidly than the reference level 40, causing the profile 30 to reach the reference level 40 relatively quickly. This in turn causes the output of the operational amplifier to reverse so that the output at 62 changes state and allows appropriate alarm action to be taken. The capacitor C2 provides positive feedback for the amplifier and the time constant (R3xC2) controls the output pulse width at 62. This time constant has negligible effect on the main time constant (R2xC1). In the example shown, the output 62 is provided to a microcontroller 64 programmed to take appropriate action when an obstruction is detected.

Other components of the circuit 58 assist in preventing false triggering by an initial peak 32. Another voltage divider R4,R5 provides a voltage to point B' through a blocking diode D1 , from which point capacitor C3 is connected to the positive supply rail V . Point B' is connected to a microcontroller output 66 through resistor R9 and diode D2. When the motor is off, the anode of diode D2 is held high by the output 66 to tend to pull the capacitor C3 voltage high, but the voltage is clamped by the low value series resistors R4, R5 so that the negative input of the amplifier 60 is high relative to the positive input. When the motor is turned on by the microcontroller 64, output 66 goes low. Diode D2 is now reverse biassed to remove the effect of resistor R9 from the circuit. There follows a short period during which the capacitor C3 charges to bring voltage B' down to the level of B so that tracking described above can then begin. It is during this initial period that the peak 32 occurs and is therefore ignored by the amplifier 60.

It may be that on occasions sharp peaks in the profile 30 may arise legitimately. If so, the micro¬ controller can take the output 68 high to forward bias diode D3 and allow current to flow through resistor R10, thereby modifying the potential divider forming voltage B, to hold B further above voltage A.

The motor direction and speed is controlled by the switches 52, described above, and switch 70. The switches 52A,B allow current to be passed in either sense through the motor, thereby allowing the direction to be reversed. The switch 70 has two positions, one of which applies the full supply voltage to the motor, the other of which applies a reduced voltage for slower speed operation. These switches (which may be relays) are all controlled from the microcontroller 64.

Instructions to the microcontroller can be received either by a push switch 72, probably located within the garage, or from a portable transmitter, preferably a radio transmitter. This sends a signal to an antenna 74 connected to a receiver 76 which demodulates the signal at 78 and amplifies at 80 before supplying a signal to the microcontroller.

Once installed, a typical operating sequence of the apparatus would proceed as follows. On the first operation, the microcontroller is instructed to begin opening (or closing) the door and sets the switches 52,70 to operate at slow speed. The microcontroller times the operation until an obstruction is encountered, which it assumes to be the other limit of the movement. The motor is then reversed and again, the microcontroller 64 measures the time to the next limit. This provides an expected time for the complete travel. In future cycles, the reaction to an obstruction sensed while closing depends on the point in the cycle at which the obstruc¬ tion is sensed. If it is sensed before about 90?ό of the closing cycle has been completed, the motor is automati¬ cally stopped and reversed to open the door, thereby releasing anything trapped. After the 90?ό point, the motor merely stops, either because it has found an obstruction (such as a foot under the door) or because it has in fact fully closed but mis-calculated the timing. This may be as a result of change in ambient wind speed etc. At the end of each closing operation, the total time and the 90 % time are re-calculated.

During opening, the motor simply stops, if an obstruction is sensed.

The microcontroller may also be used to change the switch 70 as the door approaches the closed position. This feature is particularly useful with doors which swing down to close, because it tends to prevent the door slamming. Since the door approaches the closed position more slowly, the risk of items being trapped is further reduced. The point in the cycle at which the change in speed occurs could be the same as the 90°ό point mentioned above, or an alternative point could be chosen.

The above basic system can be embellished in various ways.

Security can be improved by providing a lock 82 controlled by the microcontroller. The lock 82 is positioned to lock the door closed. The bolt is withdrawn when the door is to open, and is advanced when movement ceases at the end of a closing cycle. There may be two locks mounted on the frame, one engaging the door at each side. In addition to this, the microcontroller 64 sets the switches 52 to the positions shown, when no motor operation is required. This shorts the motor coils. The motor then cannot be turned even with substantial force applied to the door, for instance by an unauthorised person attempting to break in. If this arrangement is used, it is preferable to provide a permanent linkage from the motor to the door. In particular, it is desirable not to provide a linkage which can be manually disconnected to allow manual operation of the door, because human error may then lead to this linkage not being re-connected, so that the security of the door is prejudiced. Since manual operation of the door is then no longer possible, it is advantageous to drive the motor from a battery 54, as shown, rather than to be dependent on an external source and to ensure the battery has adequate capacity to open or close the door several times before becoming drained, and to provide a battery charging system 84 driven from a mains supply 86 to keep the battery fully charged. An adequate battery 54 can more easily be provided if the motor is a low voltage DC motor, such as a motor operating below about 50V.

In one envisaged arrangement, the push switch 72 has multiple uses according to the sequence of operation, i.e. the number of user operations, and the timing and duration of those operations. Thus, the microcontroller 64 monitors operations of the switch 72 to detect certain predetermined sequences of operations which authorise certain functions to be performed. One sequence would authorise the door to be opened or closed (according to its present condition). Another may authorise a light to be illuminated. A light 88 is shown, controlled by a switch 90 set by the microcontroller 64.

The third sequence may be used by a legitimate user to disable the control apparatus either until another sequence is detected, or for a predetermined time. Thus, when a user is to be away from premises for a substantial period of time (for instance on holiday) the control apparatus can be disabled until the user returns. Alternatively, if children are playing with the apparatus, so that a number of actuations in excess of a predetermined number occurs within a set period of time, the apparatus can then be disabled for a set time to discourage the children from playing.

Another sequence may allow signals to be received at the antenna from a new remote control device with distinctive signal patterns, so that that device can in future be recognised and therefore authorised to instruct the apparatus. This allows the user to replace a lost remote control device quite simply.

Another safety feature is based around a microphone 92 which feeds an amplifier 94, a filter 96 and a sensor 98. The microphone monitors ambient noise levels. The microphone signal is amplified to usable levels and then filtered in a band pass filter 96 to select a range of frequencies in which the human voice will lie. The resulting signal is applied to a sensor 98 which may be based on the same arrangement as the circuit described above for sensing motor current. Thus, ambient noise levels would be sensed and a threshold level would track the ambient level with a longer time constant, so that if a sudden loud noise is detected, resulting in a fast change in the noise level detected, the threshold will be exceeded and an alarm signal sent to the microcontroller

64. Thus, an adult shouting to a child who is in danger of becoming trapped in the mechanism would create a sudden sound significantly above ambient levels. This would be sensed and allow the microcontroller to take appropriate action. This safety feature is envisaged to be particularly useful for general application in many different circumstances, and might, for instance, be used to allow a person to instruct a lift door or other door to stop closing, or to reopen during a closing cycle.

The microcontroller 64 may be programmed initially to count the number of operations of the door, and then to disable the apparatus (or to disable the remote control function). This gives an installer some control over payment by his customer. If payment has been received when the door is disabled, the microcontroller can be instructed to continue normal operation, for instance by changing a switch setting.

The microcontroller may incorporate speech processing facilities, allowing it to issue instructions or warnings through a loudspeaker 100.

By way of example, the components shown in Fig. 3 could have the following values:

COMPONENT VALUE

Resistors : R1 0.22 ohm

R2 1M

R3 120K

R4 1K

R5 1K

R6 820 ohm

R7 33K

R8 120K

R9 120K

R10 120K

Capacitors : C1 0.047 uF

C2 0.1 uF

C3 10 uF

C4 2200 uF

Comparator: 60 LM339 (1 of 4 in package)

Diodes D1 BAS16

D2 BAS16

D3 BAS16 This circuit would use a supply V at about 8V.

Many variations and modifications of the apparatus described above are possible within the scope of the invention. In particular, the features described can be used in various combinations or alone, with or without other features which are not described. The circuit has been described with reference to a DC supply and DC motor, but could readily be adapted for use with an AC supply and AC motor. It would then be convenient to convert to DC, for instance by means of a current transformer, but alternative sensing techniques could be used in order to derive a signal indicative of the parameter being monitored. The circuit 58 could be replaced by a circuit which uses the analogue voltages at A and B to generate frequencies which are then mixed. The use of different time constants could then ensure that beat frequencies arise when an abnormality occurs, or are normally present and disappear when an abnormality occurs. Alternatively, voltage levels could be converted to digital values to allow digital comparisons.

In addition to the applications described, the apparatus could be used for controlling many types of movable member, including motorised boat davits or gangways. In all these applications, any blockage, damage, interference or obstruction causing excessive motor current can be detected, as can the end points of the movement of the movable member.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

C L A I MS

1. Monitoring apparatus for monitoring variations in a parameter, comprising signal generating means operable to provide first and second signals which vary in response to variations of the parameter being monitored, comparison means operable to compare the first and second signals, and time constant means operable to provide time constants which govern the responses of the signal generating means, the time constant means causing the second signal to be governed by a longer time constant than the first, whereby the comparison result will vary in accordance with the rate of change of the parameter.

2. Apparatus according to claim 1, wherein the first time constant means is operable to pass the said level to the comparison means after a delay governed by a first time constant.

3. Apparatus according to claim 1 or 2, wherein the first and second signals are derived from the voltage or current level at a common point.

4. Apparatus according to any of claims 1 to 3, wherein the said voltage or current level is directly derived from the parameter being monitored.

5. Apparatus according to claim 3 or 4, wherein the apparatus further comprises intermediate means operable to derive an intermediate signal from which the second signal is derived, the intermediate means providing a signal level governed by the signal levels at the common point and at a reference point.

6. Apparatus according to claim 5, wherein the intermediate means preferably comprises a potential divider tapped to provide the intermediate signal.

7. Apparatus according to claim 5 or 6, wherein second time constant means are operable to pass the intermediate signal to the comparison means after a delay governed by the second time constant.

8. Apparatus according to any preceding claim, wherein at least one time constant means comprises a capacitance and resistance in series.

9. Apparatus according to any preceding claim, wherein control means are provided, operable to change one or both time constants to modify the responses during periods in which the rate of change is expected to be substantially different to the rate outside the period.

10. Apparatus according to any preceding claim, wherein the comparison means is operable to provide a voltage or current comparison.

11. Apparatus according to any of claims 1 to 9, wherein the comparator is operable to encode the first and second signals as digital signals and make a digital comparison thereof.

12. Apparatus according to any of claims 1 to 9, wherein the comparison means is operable to create first and second comparison signals at frequencies which depend on the levels of the first and second signals, and to compare the frequencies of the comparison signals.

13. Apparatus according to any preceding claim, in which alarm means are provided to recognise an alarm condition in response to a predetermined output or range of outputs of the comparison means.

14. Apparatus according to any preceding claim, wherein the parameter monitored is the torque of a motor.

15. Apparatus according to claim 14, wherein the first and second signals are derived from motor current.

16. Apparatus according to any of claims 1 to 13, wherein the parameter being monitored is the noise level in an environment.

17. A control system for automatically moving a movable member between first and second positions, comprising lock means operable to lock the movable member in at least one of the positions, and means operable to release the lock means, if locked, when the control system is correctly instructed to move the member, and to engage the lock means when the member reaches the other of the said positions.

18. Control apparatus for a movable member, comprising switch means, detector means operable to detect operations of the switch means, and control means operable to select a function to be performed by the control apparatus, the function being selected in accordance with the detected sequence of operations.

19. Apparatus according to claim 18, wherein a first detectable sequence authorises the opening or closing of the closable member.

20. Apparatus according to claim 18 or 19, wherein a second detectable sequence may authorise the illumination of a light source.

21. Apparatus according to claim 17, 18 or 19, wherein a third detectable sequence may authorise disabling of the control apparatus.

22. Apparatus according to claim 21, wherein disabling may be for a predetermined time or until a further authorising sequence is detected.

23. Apparatus according to claim 21 or 22, wherein the third sequence is repeated actuation in excess of a predetermined number within a second set period of time.

24. Apparatus according to any of claims 17 to 23, wherein a fourth detectable sequence may authorise the programming of the control apparatus to receive instructions from a remote control device.

25. Control apparatus for a movable member, comprising counter means operable to count operations of the apparatus and to disable the apparatus after a predetermined count is reached.

26. A security system comprising a movable member, an electric motor for controlling the position of the movable member, and a back-up battery operable to supply the motor in the absence of an external supply.

27. Apparatus according to claim 26, wherein the electric motor is a low voltage DC motor.

28. Apparatus according to claim 26 or 27, wherein charging means are provided for charging the battery from an external supply.

29. A security system comprising a movable member, an electric motor for controlling the position of the movable member, means operable to short the motor coils when not in use, and means providing a permanent drive linkage between the movable member and the motor.

30. Control apparatus for a movable member, comprising speed selection means operable to change the speed at which the movable member is driven, and to provide a reduced speed as the member approaches a predetermined position.

31. Control apparatus for a movable member, comprising sound detection means operable to detect sudden sounds significantly above ambient levels, and means operable to stop the movable member from moving when a sound as aforesaid is detected.

32. Apparatus according to claim 31, wherein the sound detection means incorporates monitoring apparatus in accordance with any of claims 1 to 16.

33. Control apparatus for a movable member, comprising drive means operable to drive the movable member, and monitoring apparatus in accordance with any of claims 1 to 16.

34. Apparatus according to claim 32, wherein the monitoring apparatus is operable to monitor the load on the drive means and to stop the drive means when an abnormal load is detected.

35. Apparatus according to claim 33 or 34, wherein the monitoring apparatus is operable to monitor ambient noise levels, and to stop the drive means when an abnormal level is detected.

36. Apparatus according to any of claims 33 to 35, and incorporating apparatus according to any of claims 17 to 32.

37. Apparatus according to any of claims 33 to 36, wherein the apparatus is operable to stop when an obstruction is detected while the movable member is moving.

38. Apparatus according to claim 37, wherein the apparatus may cause the movable member to reverse direction when an obstruction is detected while the movable member is moving.

39. Apparatus according to claim 38, wherein the movable member may reverse direction only if the obstruction is detected during a first part of the moving phase, the member being merely stopped if the movable member is at or near an end position of the movement.

40. Monitoring apparatus substantially as described above with reference to the accompanying drawings.

41. Control apparatus substantially as described above with reference to the accompanying drawings.

42. Any novel subject matter or combination including novel subject matter disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.