GB2521160A

GB2521160A - Safety device

Info

Publication number: GB2521160A
Application number: GB1321858.1A
Authority: GB
Inventors: Barry Jude Fennessy
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-12-10
Filing date: 2013-12-10
Publication date: 2015-06-17
Also published as: WO2015087068A1; GB201321858D0

Abstract

A remotely controllable shut-off system for a machine 1 includes a deactivation device for preventing operation of the machine, a receiver for receiving signals from a remote unit 3, and a control unit for controlling actuation of the deactivation device. The control unit includes an input and is configured to actuate the deactivation device in response to receipt of a first, de-activation signal from the remote unit 3 by the receiver to prevent operation of the machine, and is further configured to disable the deactivation device to resume operation of the machine in response to both receipt of a second, re-activation signal from the remote unit 3 by the receiver and activation of the input of the control unit. The system further includes an override mechanism configured to disable the deactivation device independently of the control unit input to resume operation of the machine.

Description

SAFETY DEVICE

Technical Field

The present invention relates to a remotely controllable shut-off device for machinery.

Background

Safety devices for remotely controlling machinery in the event of a need for an emergency shut-off are well-known.

For example, US 7,005,997 discloses a remotely controllaNe shut-off system for temporarily shutting off a machine that comprises a receiver unit in the vicinity of the machine and a remote transmitter communicable with the receiver unit. When a shut-off signal is generated by the transmitter, the receiver is configured to immobilise the machine, and operation of the machine may only be resumed once the transmitter and/or the receiver have been reset. A mode of operation of the system is described in US 7,005,997 in which both the transmitter and receiver need to be reset before operation of the machine can be resumed; this enhances the safe operation of the machine because two individuals are required to approve resumption of operation.

However, a disadvantage of this mode of operation is that when only one of the individuals perceives a further danger, in addition to the danger that prompted the initial machine shut-off, and aversive action needs to be taken to avoid that danger, there is no means of taking the necessary aversive action if the other of the two individuals cannot be informed of the further danger sufficiently quickly, For example, in the event that the machine is an excavator and the excavator is initially shut-off to avoid hitting an &ectrical cable and a driver of the machine sees that another vehicle is approaching it in such a manner that a collision is anticipated but an operator of the remote transmitter does not perceive that danger, no action can be taken by the driver to avoid the collision.

Although there is also a mode of operation of the system disclosed in US 7,005,997 in which the system can be reset by only one individual, this mode of operation significantly reduces the overall safety of the system.

It is an object of the invention to mitigate the disadvantages of prior art remotely controllable shut-off systems.

Summary

According to a first aspect of the present invention, there is provided a remotely controllable shut-off system for a machine comprising a deactivation device for preventing operation of the machine; a receiver for receiving signals from a remote unit; and a control unit for controlling actuation of the deactivation device, the control unit including an input and being configured to actuate the deactivation device in response to receipt of a first, dc-activation signal from the remote unit by the receiver to prevent operation of the machine, and further being configured to disable the deactivation device to resume operation of the machine in response to both receipt of a second, re-activation signal from the remote unit by the receiver and activation of the input of the control unit. The system further comprises an override mechanism configured to disable the deactivation device independently of the control unit input to resume operation of the machine. This system permits safe operation of a machine, for the operator, and also for people in the vicinity of the machine. A first safeguard is provided by a requirement for two separate signals to be received for the machine to be re-activated after dc-activation, Furthermore, in the event that an additional danger is perceived by a machine operator during or following de-activation of the machine, the override mechanism that operates independently of the control unit input enables action to be taken to avoid that danger.

In an embodiment of the invention, the override mechanism comprises a switch for selectively turning on and off the machine. This allows the override mechanism to be readily incorporated into the existing machine infrastructure and is also easily operable by the operator due to the familiarity of its function, In a further embodiment of the invention, a monitoring device is provided for recording information on actuation of the deactivation device. By monitoring the actuation of the deactivation device, data on the usage of the deactivation device can be obtained and analysed, allowing for misuse of the deactivation mechanism to be identified, for example, but also possible incompetent operation of the machine. If a machine operator persistently encounters danger and requires remote deactivation of the machine under their control, this may point to a lack of skill in operating the machine. On the other hand, repeated dc-activation of a particular machine by a remote operator may indicate a deliberate attempt by the remote operator to interfere with the work of the machine operator. Monitoring of the use of the deactivation device can be useful in identifying such issues.

In a yet further embodiment of the invention, an indicator is provided for alerting a machine operator in the event that a first dc-activation signal has been received by the receiver. Increasing the awareness of the machine operator to the imminent deactivation of the machine reduces the risk of accident. Furthermore, in some circumstances, it may be possible to avoid deactivation of the machine once the machine operator becomes aware of a potential danger; the indicator can be useful in these circumstances to initially alert the machine operator to the potential danger.

In an embodiment of the invention, a transmitter is provided wherein upon activation of the override mechanism, the transmitter is configured to transmit a signal to the remote unit to indicate activation of the override mechanism. This enables the machine operator to make a remote unit operator aware of the activation of the override mechanism in response to a further danger that may not have been appreciated by the operator of the remote unit. The remote unit operator can then take any further necessary action in respect of other machines or personnel in the area.

In another embodiment of the invention, the control unit is configured to disable the deactivation mechanism only if a time interval between the receipt of the second, re-activation signal by the receiver and the activation of the input of the control unit, or between the activation of the input of the control unit and the receipt of the second, re-activation signal by the receiver is within a predetermined range.

This ensures that the reactivation of the machine is carried out only once both an operator of the remote unit arid an operator of the machine decide that it is safe or necessary to do so, and that the decisions are made sufficiently close to one another in time for them to remain valid. For example, if a remote unit operator were to decide that it was appropriate to re-activate the machine and ten minutes later, the machine operator also decided that it was appropriate to do this, the lapse often minutes may have resulted in a change in circumstances causing a switch in the remote unit operator's decision regarding the ability to operate the machine, By restricting the permitted time delay between remote operator and machine operator decisions to effect re-activation of the machine, safety of operation of the machine is enhanced. A time interval in the range of 0-60 seconds is preferred.

In a further embodiment of the invention, a communication device is provided for permitting communication between an operator of the machine and other personnel remote from the machine. Allowing communication between the operator of the remote unit and the operator of the machine enables explanations to be provided as to why the machine has been de-activated or re-activated and also permits discussions as to how potential dangers can be addressed. In a case where a hazard is not perceived as requiring immediate avoidance, for example, the operator of the remote unit may communicate with the operator of the machine to ascertain a way of avoiding the hazard before activating the remote control unit to shut down the machine. Any unnecessary shut-down of the machine that can be avoided in this manner is beneficial.

In accordance with an embodiment of the invention, a range sensor is provided for detecting whether the receiver is in communication range of the remote unit and issuing an alert when the receiver and the remote unit are not in communication range of each other. This feature strengthens the safety aspects of the system.

In accordance with another embodiment of the invention, a safeguard device is provided for preventing inadvertent activation of the override mechanism.

Inadvertently activating the override mechanism can place the machine operator or other personnel in danger. Therefore, it is advantageous to ensure that the override mechanism is only activated intentionally when the respective dangers under consideration have been adequately contemplated.

According to a second aspect of the invention, there is provided a remotely controllable shut-off system for a machine comprising a deactivation device for preventing operation of the machine; a receiver for receiving signals from a remote unit; and a control unit for controlling actuation of the deactivation device, the control unit including an input and being configured to actuate the deactivation device in response to receipt of a first, de-activation signal from the remote unit by the receiver to prevent operation of the machine, and further being configured to disable the deactivation device to resume operation of the machine in response to both receipt of a second, re-activation signal from the remote unit by the receiver and activation of the input of the control unit. The system further comprises an override mechanism configured to disable the deactivation device independently of the control unit input to resume operation of the machine, and a remote unit for issuing the first, deactivation signal and the second, reactivation signal.

In accordance with an embodiment of the second aspect of the invention, the remote unit is configured to selectively transmit the first, deactivation signal and the second, reactivation signal to one or more of a plurality of machines. Where extreme danger to all machines was anticipated, for example, all machines could be shut off by the remote unit substantially simultaneously, thus considerably improving the safety of the environment in which the plurality of machines is located.

In accordance with another embodiment of the second aspect of the invention, the remote unit is a mobile communications device. This alleviates the need to have a separate unit to act as the remote unit, reducing the amount of equipment that is required to be carried by a remote unit operator. It also has the benefit of providing a means of two-way communication with a machine operator, assuming that the machine operator is also carrying a mobile communications device. Alternatively, the remote unit is in the form of an electronic key fob, which is relatively compact and easy to carry. Furthermore, the combination of the remote unit's control functionality with key fob functionality reduces the number of items to be carried by an operator of the remote unit.

In accordance with a yet further embodiment of the second aspect of the invention, activation of the remote unit is controlled by a password, This ensures that only operators with appropriate authorisation are able to operate the remote unit and, therefore, remotely control deactivation and re-activation of the machine.

According to a third aspect of the invention, there is provided a method of remotely controlling a machine comprising receiving a first, deactivation signal from a remote unit at a receiver; actuating a deactivation device for preventing operation of the machine in response to receipt of the first, deactivation signal; receiving a second, re-activation signal from the remote unit at the receiver; activating an input of a control unit, and disabling the deactivation device in response to receipt of the second, re-activation signal and the activation of the input of the control unit, further comprising providing an override mechanism to permit disablement of the deactivation device independently of the input of the control unit to resume operation of the machine.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings.

Brief Description of the Drawings

Figure 1 shows a schematic representation of a remote shut-off system, in accordance with one embodiment of the invention; Figure 2 shows a simplified circuit diagram for part of a remote shut-off system, in accordance with one embodiment of the invention.

Figure 3 shows a flow chart of the steps involved when a remote shut-off is initiated in accordance with an embodiment of the invention; and Figure 4 shows a flow chart of the steps involved when a remote shut-off is overridden in accordance with an embodiment of the invention.

Detailed Description

The safety system for permitting remote shut-off of a machine disclosed herein includes a machine control unit within or in the vicinity of the machine that can be configured to shut-off the machine, and a remote control unit for remotely communicating with the machine control unit. The machine control unit, or control unit, and the remote control unit, or remote unit, are intended to be operated by at least two individuals, one individual being intended to operate the machine control unit, the other individual being intended to operate the remote control unit.

Figure 1 shows a schematic view of a remotely controllable shut-off system for a machine 1. A machine control unit (not shown) is arranged within the interior of the machine in a position that is physically accessible to an operator 2 of the machine.

The machine control unit is arranged to be in communication with a deactivation or shut-off device of the machine (not shown). The deactivation device can be a device that mechanically shuts off the machine, such as a movable arm or lever that acts to obstruct the functional, usually movable, parts of the machine in such a way as to render them dysfunctional. However, the deactivation device can alternatively be an electrical or electronic device that interrupts a power supply to the functional parts of the machine or otherwise causes them to stop by issuing an appropriate signal. There is also a receiver (not shown) in the interior of the machine for receiving signals from a remote control unit 3. The receiver in the interior of the machine can be part of the machine control unit or it can be a distinct component that is communicable with the machine control unit.

The machine control unit additionally comprises an input that is activatable by the operator 2 of the machine 1. The input can be activated within the machine control unit directly or by activation of a further input external to the machine control unit that is communicable with the input of the machine control unit. The machine control unit could include, for example. an input in the form of a button activatable by the operator 2. However, a distinct button, switch or other input activatable by the operator 2 could be located elsewhere within the interior of the machine I and merely connectable to the input of the machine control unit. Whilst it is envisaged that the input would require manual activation by the operator 2, it could also be voice-activated. The machine control unit could be a battery-operated wireless device or it could be connected to a power supply of the machine and be communicable with other machine components in a wired or wireless manner. For example, where a distinct input (as opposed to integral input), such as a button or switch is connected to an input of the machine control unit, the connection therebetween could be wireless.

The machine control unit may include a range sensor for detecting whether the receiver is within communication range of the remote control unit 3. Should the receiver depart from a communication range of the remote control unit 3, an alarm or alert could be emitted by the control unit, for example an audible, visual or motion-based alarm, such as a vibrating alarm. Ideally, the communication range would be around t kilometre but it could be higher or lower than this.

The interior of the machine I may include an indicator, such as a visual or audible indicator or alert system, so that the operator 2 can be informed of any planned or ongoing shut-off of the machine, or in the case where shut-off has already taken place, any planned reactivation of the machine. For example, a visual indicator might include a light or a screen that is visible to the operator 2 for displaying messages to the operator. In addition, or as an alternative, an audible indicator in the form of a bell, siren or a speaker for outputting a recorded voice message could be included within the interior of the machine 1. The indicator could be configured to receive a signal directly from the remote control unit 3 and emit a corresponding alert to the operator 2 of the machine 1, Alternatively, the indicator could be communicable with the machine control unit and receive signals therefrom following transmission of corresponding signals to the machine control unit from the remote control unit. It is further envisaged that a communication device would be included within the interior of the machine I to permit the operator 2 to communicate with an operator of the remote control unit 3, which would be particularly useful in the event of a machine shut-off Such a communication device could be a wireless communication dcvice, such as a mobile telephone or a two-way radio. The communication device could be voice-activated to permit operation of the device in a hands-free manner. In particularly noisy environments in which a visual indicator may also be an undesirable distraction for the operator 2, a motion indicator in the form of a vibrating device could be employed. The indicator could be combined with or integrated with the range sensor described above.

A monitoring device (not shown) can also be provided within the interior of the machine 1 to record data on machine shut-offs. For example, the time, date, frequency and identity of an operator (or operators) responsible for the shut-off could be recorded, The monitoring device can be wirelessly communicable with the control unit and/or receiver to enable the relevant data to be recorded. Alternatively, the monitoring device can be operated independently of the control unit and/or receiver and can instead be updated with shut-off data by the operator 2 of the machine, either manually or by voice activation. It will be appreciated, however, that a reduced number of errors and inaccuracies would be expected in the event that the monitoring device is automatically updated by virtue of a connection to the control unit, rather than being updated by the operator 2. The monitoring device could be configured to transmit a message or report when a predetermined number of machine shut-offs has been recorded or when a certain operator has been responsible for a predetermined number of machine shut-offs.

The interior of the machine 1 may also include a transmitter for sending signals relating to operating status of the machine to the remote control unit 3, The transmitter could be included in the machine control unit or the communication device mentioned above but could, alternatively, be a separate component.

An override mechanism is also arranged within the machine 1. The override mechanism is accessible to the operator 2 so that, in an emergency, any previous shut-off of the machine can be reversed. The override mechanism is configured to disable the deactivation device and permit resumption of operation of the machine. This can be achieved by transmifting a signal to the machine control unit to effect disablement of the deactivation device or by transmitting a signal directly to the deactivation device. The override mechanism can be combined with an overall on/off or activation mechanism for the machine 1. For example, where the machine I is a vehicle, the override mechanism can be incorporated in the ignition switch, However, a voice-activated override mechanism is also envisaged.

The override mechanism can also transmit a message to the remote control unit 3, either directly or via the transmitter or communication device described above, to indicate that the override mechanism has been activated. This could alert an operator of the remote control unit 3 to a danger that might affect other machines in the vicinity.

The override mechanism could also be linked to the monitoring device 212 described above so that its activation could be monitored, Alternatively, it may have an in-built monitoring device for monitoring data on its activation.

In order to prevent inadvertent activation of the override mechanism, a safeguard could be provided in the vicinity of the override mechanism. Such a safeguard might include a physical cover over an activation switch of the override mechanism or a physical or technical barrier to activation of the override mechanism, For example, a personal identification number might be required to provide access to the override mechanism or to permit its activation, The remote control unit 3 is depicted in Figure 1 as a wireless remote control unit 3. However, it will be understood that is not essential that the remote control unit 3 be wireless. Similarly, whilst it is desirable that the remote control unit 3 be handheld, this is not a requirement.

The remote control unit 3 could have additional functions other than transmitting signals to the machine control unit in the event that a machine shut-off is required. For example, the remote control unit 3 could be embodied in a mobile communication device such as a two-way radio communication device or a mobile telephone. Alternatively or in addition, the remote control unit 3 could ifinction as an electronic key fob, The remote control unit 3 can be protected from unauthorised use by means of a personal identification number or another identification criterion that is required to be entered before the remote control unit 3 can be activated, The remote control unit 3 may also have a sensor to detect whether it is within communication range of a machine that it is intended to control and can issue an alert signal in the form of a visual or audible signal in the event that it is not in communication range of that machine, Separate user inputs can be provided on the remote control device 3 for selectively producing deactivation and reactivation signals.

Figure 2 shows a simplified circuit diagram for part of a remote shut-off system, in accordance with one embodiment of the invention. In particular, Figure 2 illustrates control circuitry within the machine control unit.

The processes that occur in the event of a shut-off of the machine I are outlined in Figure 3. Following transmission of a first, deactivation signal by the remote control unit 3, due to a danger perceived by an operator of the remote control unit 3 and in response to activation of the remote control unit 3 by the operator of that unit, the deactivation signal is received by machine control unit circuitry 200 via a receiver unit 201.

In one embodiment, the receiver unit 201 is a radio frequency ultra high frequency (BY UHF) receiver, The machine control unit is supplied by power supply 202, which in some embodiments may be sourced from the machine itself The receipt of a first de-activation signal from the remote control unit 3 causes current to be supplied at a first input 203, causing a first relay 204 to be momentarily activated so that a current is supplied to a gate of a thyristor 205 allowing current to flow through the thyristor 205. Current is then supplied to a second relay 206 which causes a deactivation device 207 in the machine to be activated to prevent operation of the machine.

The operator of the remote control unit 3 may communicate with the operator 2 of the machine Ito indicate why the machine has been deactivated.

When it has been determined that the danger that caused the machine shut-off no longer exists, the operator of the remote control unit 3 can cause a second re-activation signal to be transmitted by the remote control unit 3 to the machine control unit circuitry 200.

The operator of the remote control unit 3 should then communicate with the operator 2 of the machine 1 to indicate that reactivation is intended, either using hand gestures or using a communications device, which may be the remote control unit 3 itself, or by transmitting an alert signal from the remote control unit 3 to the machine control unit circuitry 200 or directly to the indicator in the interior of the machine described previously. When the operator 2 of the machine 1 knows that reactivation of the machine is planned, he or she can then activate the input 209 of the machine control unit.

In the event of a second reactivation signal reactivation being transmitted to the machine control unit circuitry 200 a current is provided at a second input 208.

The activation of the input 209 of the machine control unit in combination with the receipt of a second reactivation signal by the machine control unit circuitry 200 from the remote control unit 3 causes a third relay 210 to be momentarily activated, which removes current from an anode of the thyristor 205, and causes the supply to the deactivation device 207 to be removed, which disables the deactivation device 207 so that operation of the machine can be resumed. This reactivation can be limited to a certain predetermined time interval, such as 0-60 seconds, so that if both the input 209 of the machine control unit and the second reactivation signal are not received within this predetermined time interval, reactivation is not permitted. It is important to note that either activation of the input 209 of the machine control unit or the receipt of a second reactivation signal by the machine control unit circuitry 200 will not be sufficient in itself to disable the deactivation device 207.

In some cases where a hazard is not perceived as requiring immediate avoidance action, the operator of the remote control unit 3 may communicate with the operator 2 of the machine I before activating the remote control unit 3 to attempt to avoid the hazard being encountered at all and to avoid unnecessary shut-off of the machine, This communication may be via an independent communications device or direct from the remote control unit 3, either in its function as a mobile communications device or by transmitting a signal to the machine control unit 200 or directly to the indicator in the interior of the machine described above. In the event that communication is taking place via the indicator in the interior of the machine only, certain codes can be applied to communicate particular messages to the operator 2. For example, visual or audible alerts in a certain sequence could indicate that a person is in close proximity to the machine. An alternative sequence of alerts could indicate dangerous proximity to electrical cables.

In the event that the operator 2 of the machine perceives a further danger when the machine 1 has already been shut-off due to an earlier risk, they can override the shut-off of the machine 1 by activating an override mechanism in the form of an override switch 211, as illustrated in Figure 4. This provides an additional safety mechanism in the event that the operator of the remote control unit 3 does not appreciate the further danger, for example, because it is not within the range of their vision. The activation of the override switch 211 results in a signal being sent by the override switch 211 to the deactivation device 207 directly or via the machine control unit circuitry 200 so that the deactivation device 207 can be disabled and the machine 1 operation resumed so that the further danger can be averted by the machine operator 2. It is possible that a transmitter in the machine will then transmit a message to the operator of the remote control unit 3 to alert the operator of the remote control unit 3 to the resumption of the operation of the machine.

If the override switch 211 is protected by a safeguard to prevent inadvertent activation of the override switch 211, the operator 2 of the machine 1 will need to remove that safeguard before proceeding to activate the override switch 211. For example, a personal identification number may need to be entered to permit activation of the override switch 211 or a physical cover over the override switch 211 may need to be removed prior to its activation, Where the override switch 211 is incorporated in the on/off switch of the machine, for example, it may be required to initially turn the switch in a direction counter to the usual direction required for switching on the machine and then to turn the switch in the usual direction for switching on in order for the override switch 211 to be activated.

Activation of both the deactivation device 207 and the override switch 211 can be monitored by the monitoring device in the form of a monitor 212, As described above, the monitoring device or monitor 212 can provide data on the overall safety of operation of the machine and also on abuse of the deactivation device 207 and/or override switch 211 by certain remote control unit and/or machine operators.

It will be appreciated that the machine I discussed above may be operated in an environment in which several machines are operating. Therefore, it is possible that information relating to the status of the machine 1 will be distributed more widely in that environment. For example, the fact that the machine 1 has been deactivated or reactivated could be communicated to every other machine in the vicinity by means of the remote control unit 3 or by means of a transmitter in the interior of the machine I. Furthermore, any audible or visual alerts that are issued by the indicator in the machine could be such that they would be receivable by operators of other machines.

If an audible alert were suitably loud, for example, all operators of machines in the environment would be able to receive it. Alternatively, a single common indicator could be provided in the environment so that in addition to audible or visual alerts within the interior of the machine, an alert could be transmitted to the common indicator for reception by all machine operators. In the event that another safety product, such as the MYZONEIM system supplied by TI Global Pty Ltd, was being used in that environment, this could be combined with the system outlined above, with transmission of a first, dc-activation signal by the remote control unit 3 activating MYZONEIM receivers of personnel within the vicinity.

In the event that several machines are operating in an environment, a single remote control unit 3 could be configured to control machine control units in each of the machines. Where extreme danger to all machines was anticipated, all machines could be shut off.

The signals transmitted and received between the remote control unit 3 and the machine control unit circuitry 200 can be radio signals, infrared signals or any other

suitable signals.

The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invention are envisaged. For example, the range sensor in the machine could be incorporated in the receiver 201, rather than in the machine control unit, where the receiver 201 and machine control unitare distinct.

Similarly, the receiver 201 could emit an alarm or alert when it was no longer in range of the remote unit.

Whilst the indicator is described above as being located in the interior of the machine, it will be appreciated that it can be located anywhere in which its output would be perceptible to a machine operator.

The deactivation device 207 may only deactivate part of the machine, rather than the whole machine. For example, where the operation of an excavator is being remotely controlled, movement of the excavator bucket can be prevented but the machine may still be driven.

A first, deactivation signal could be transmitted in the event of a machine moving beyond a predetermined distance from the remote unit or beyond, preventing unwanted use of a machine when it can no longer be viewed or there is a significant risk of it departing from the communication range of the remote unit.

In the event that either or both of the remote unit 3 and the machine control unit are battery-operated, an alert can be issued when a battery needs to be replaced.

It will be appreciated that the remotely controllable shut-off system described above is applicable to machines in a wide variety of industries, including constmction, manufacture, energy generation, agriculture and recreation. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims

Claims I. A remotely controllable shut-off system for a machine comprising: a deactivation device for preventing operation of the machine; a receiver for receiving signals from a remote unit; and a control unit for controlling actuation of the deactivation device, the control unit including an input and being configured to actuate the deactivation device in response to receipt of a first, dc-activation signal from the remote unit by the receiver to prevent operation of the machine, and further being configured to disable the deactivation device to resume operation of the machine in response to both receipt of a second, re-activation signal from the remote unit by the receiver and activation of the input of the control unit, wherein the system further comprises an override mechanism configured to disable the deactivation device independently of the control unit input to resume operation of the machine.
2. A remotely controllable shut-off system as claimed in claim I, wherein the override mechanism comprises a switch for selectively turning on and off (starting up and shutting down) the machine.
3, A remotely controllable shut-off system as claimed in claim I or 2, further comprising a monitoring device for recording information on actuation of the deactivation device.
4. A remotely controllable shut-off system as claimed in claim 3, wherein the monitoring device is configured to record the number of times that the deactivation device is actuated.
5, A remotely controllable shut-off system as claimed in claim 3 or 4, wherein the monitoring device is configured to record information on personnel from whom first de-activation signals are received by the receiver.
6. A remotely controllable shut-off system as claimed in any preceding claim, further comprising an indicator for alerting a machine operator in the event that a first dc-activation signal has been received by the receiver.
7. A remotely controllable shut-off system as claimed in claim 6, wherein the indicator is configured to issue an audible signal.
8. A remotely controllable shut-off system as claimed in claim 7, wherein the audible signal is a pre-recorded message.
9. A remotely controllable shut-off system as claimed in claim 6, 7 or 8, wherein the indicator is configured to issue a visual signal.
10. A remotely controllable shut-off system as claimed in any of claims 6 to 9, wherein the indicator is configured to issue a vibration signal.
11. A remotely controllable shut-off system as claimed in any of the preceding claims, further comprising a transmitter, wherein upon activation of the override mechanism, the transmitter is configured to transmit a signal to the remote unit to indicate activation of the override mechanism.
12. A remotely controllable shut-off system as claimed in claim 1], wherein the transmitter is located within the control unit.
13. A remotely controllable shut-off system as claimed in any preceding claim, wherein the receiver is located within the control unit.
14. A remotely controllable shut-ofT system as claimed in any of the preceding claims, wherein the control unit is configured to disable the deactivation mechanism only if a time interval between the receipt of the second, re-activation signal by the receiver and the activation of the input of the control unit, or between the activation of the input of the control unit and the receipt of the second, re-activation signal by the receiver is within a predetermined range.
15, A remotely controllable shut-off system as claimed in claim 14, wherein the predetermined range is 0-60 seconds.
16. A remotely controllable shut-off system as claimed in any of the preceding claims, further comprising a communications device for permitting communication between an operator of the machine and other personnel remote from the machine.
17. A remotely controllable shut-off system as claimed in any preceding claim, frirther comprising a range sensor for detecting whether the receiver is in communication range of the remote unit and issuing an alert when the receiver and the remote unit are not in communication range of each other.
18. A remotely controllable shut-off system as claimed in any preceding claim, further comprising a safeguard device for preventing inadvertent activation of the override mechanism.
19. A remotely controllable shut-off system as claimed in any preceding claim, wherein the first, de-activation signal and the second, re-activation signal are radio signals.
20. A remotely controllable shut-off system as claimed in any preceding claim, wherein the first, de-activation signal and the second, re-activation signal are infrared signals.
21. A system for remotely shutting off a machine comprising a remotely controllable shut-off system as claimed in any of claims I to 20 and further comprising a remote unit for issuing the first, deactivation signal and the second, reactivation signal.
22. A system as claimed in claim 21, wherein the remote unit further comprises a communication device for permitting communication between an operator of the remote unit and an operator of the machine.
23. A system as claimed in claim 21 or 22, wherein activation of the remote unit is controlled by a password.
24. A system as claimed in any of claims 21 to 23, wherein the remote unit is configured to selectively transmit the first, deactivation signal and the second, reactivation signal to one or more of a plurality of machines.
25. A system as claimed in any of claims 21 to 24, wherein the remote unit is a mobile communications device.
26. A system as claimed in any of claims 21 to 25, wherein the remote unit is an electronic key fob.
27. A method of remotely controlling a machine comprising: receiving a first, deactivation signal from a remote unit at a receiver; actuating a deactivation device for preventing operation of the machine in response to receipt of the first, deactivation signal; receiving a second, re-activation signal from the remote unit at the receiver; activating an input of a control unit, and disabling the deactivation device in response to receipt of the second, re-activation signal and the activation of the input of the control unit, further comprising providing an overide mechanism to disable the deactivation device independently of the control unit input to resume operation of the machine.
28. A method according to claim 27, further comprising recording information on the actuation of the deactivation device on a monitoring device.
29. A method according to claim 28, wherein the recording relates to the number of times that the deactivation device is actuated.
30. A method according to claim 28 or 29, wherein the recording relates to personnel from whom a first, dc-activation signal is received by the receiver.
31. A method according to any one of claims 27 to 30, further comprising transmitting a signal to the remote unit in response to activation of the overide mechanism to indicate activation of the override mechanism.
32. A method according to any one of claims 27 to 31, wherein the deactivation mechanism is only disabled if a time interval between the receipt of the second, re-activation signal by the receiver and the activation of the input of the control unit or between the activation of the input of the control unit and the receipt of the second, re-activation signal by the receiver is within a predetermined range.
33. A method of remotely shutting off a machine according to claim 32, wherein the predetermined range is 0-60 seconds.