Apparatus, system and method for hazard warning

Abstract

: In one aspect the invention provides a personal warning apparatus to be carried by a person in proximity to at least one hazard. This apparatus including a sound pulse receiver, an alarm indicator configured to alert the person carrying the warning apparatus of the presence of a hazard, at least one radio signal receiver configured to receive timing signals and ranging signals transmitted by a hazard mounted warning apparatus, and a controller connected to the at least one radio signal receiver. The controller is configured to determine a delay time experienced between the receipt of a timing signal and the receipt of a subsequent ranging signal and to identify two or more hazard mounted warning apparatus which transmitted the ranging signals with the smallest delay times.

Description

[0001] Apparatus, system and method for hazard warning Field of the Invention

[0002] This invention relates to hazard warning systems, methods and apparatus. In various implementations the invention may facilitate identification of the orientation of a hazard relative to a user and preferably may control the form of warning provided based on this 10 identified orientation.

[0003] Background of the Invention

[0004] Environments contain hazards that the people present in the environment need to be aware of. For example, manufacturing environments can contain operating machinery which is dangerous to nearby workers and may also contain mobile plant or vehicles which present a collision hazard (vehicle on pedestrian or vehicle on vehicle). Construction sites can incorporate areas that workers are to be excluded from and can also contain plant and vehicles which forms a collision hazard. Various environments can therefore contain static hazards in addition to mobile hazards formed by mobile plant or vehicles.

[0005] Attempts have been made to develop hazard warning systems which can improve the situational awareness of people in a regional environment, and also the awareness of drivers or operators of mobile plant and vehicles.

[0006] Vehicle operators in particular need to be aware of the location and direction of travel of nearby workers to prevent collisions and injury. Similarly, workers moving in the operational area of static or moving machinery and vehicles need to be aware of the presence of this equipment, and preferably - when applicable - the direction of travel of such hazards.

[0007] Prior art hazard warning systems have been developed for these circumstances which operate using range finding technologies. These systems normally rely on transmitters and receivers mounted to hazards as well as worn by the occupants of a work environment. It is known for these prior art systems to transmit and receive optical, radiofrequency or other bands of electromagnetic radiation in the determination of distances between people and hazards. These electromagnetic based systems operatequickly based on measuring round-trip travel time of electromagnetic transmissions reflected from people and hazards in a region, with light speed transmissions allowing for multiple measurements in short time spans.

[0008] However, these electromagnetic based systems may not necessarily perform effectively, accurately or reliably in certain environments.

[0009] These systems can suffer from multipath errors occurring when a signal is reflected from a target at an angle which causes it to return to a transmitter by a convoluted path of additional reflections. These additional reflections increase the propagation time of the signal and result in an erroneous distance calculation which is larger than it should be.

[0010] Other environments can experience high levels of electromagnetic noise, such as that generated by radiofrequency sources or high-power alternating current utilised by machinery. In some situations, this noise can span the band of frequencies used by the electromagnetic transmitters of the hazard warning system, making it difficult to discern the valet returned reflections from transmitters used by the system.

[0011] Environments which contain metal structures or objects also present a challenge to electromagnetic based hazard warning systems. Metal objects present in proximity to such systems can absorb and attenuate their transmissions, preventing signal returns of appropriate power from being received and assessed to determine range information.

[0012] Hazard warning systems have also been developed which do not rely on electromagnetic radiation and in particular utilise high-frequency sound or sonar transmissions.

[0013] Although sound transmissions travel much slower than the electromagnetic radiation, they do not suffer from multipath reflection errors. Multiple reflections substantially attenuate the power of the sound signal to a point where it can be easily discerned from that of a direct path reflection. Metal objects and electromagnetic noise emissions in an environment also have no appreciable impact or effect on systems using sound transmissions.Again, sonar-based hazard warning systems can be implemented by mounting transmitters or sounders to hazards, with sonar receivers being carried or worn by people in a hazardous environment. The hazard mounted sounders can also incorporate a radio transmitter and receiver

[0014] as can the devices carried by people. The start of the transmission of a sonar pulse from the hazard can also be synchronised with a corresponding radiofrequency (R.F) transmission from the same hazard. This R.F transmission can incorporate hazard or sounder identification information in addition to marking the start of the transmission time of a sonar pulse from hazard. A receiving user device will start a timing process on receipt of the sounders initial R.F transmission with a propagation time being recorded on receipt of the corresponding sonar pulse from the hazard.

[0015] However, sonar-based warning systems experience complications in their operation due to the relatively low speed of sound in air.

[0016] Although very simple systems containing one hazard or hazard sounder can be implemented without difficulty, synchronisation and accurate hazard identification becomes a problem when multiple hazards and their associated sounders are present in the same environment.

[0017] When multiple hazards are to be monitored a sonar-based warning system needs to coordinate the transmission times of sonar pulses transmitted from these various hazards. To allow these individual pulses to be distinguished from one another all hazard sounders need to make their transmission as part of a timed sequential round-robin process.

[0018] This approach does allow such systems to operate accurately but at the cost of a significant slowdown in operational speed. As the number of hazard sounders in a system increases so does the execution time for an entire cycle of round-robin transmissions.

[0019] For reasons of accuracy and reliability it is also common for such systems to make multiple sonar transmissions in the calculation of a single range member measurement. A transmission time of 50ms is experienced if such a system were to focus on identifying ranges to objects within a 17 m radius.The transmission of a series of pulses to calculate a single range measurement results in using multiples of the single pulse 50ms propagation delay. When multiple hazard sounders are operating under a round-robin synchronisation protocol range measurement times can increase significantly to a point where users are provided with little advanced warning of nearby hazards.

[0020] In some circumstances it is useful to determine not just distance between a hazard and a user but also the relative orientation or actual position of a user with respect to the hazard. In particular, in the case of forklifts the greatest danger of collision usually comes from the front of the machine which generally moves forward and swings the loaded it carries in a forwardfacing lateral arc. However, forklifts and other types of mobile hazards are also capable of moving in reverse as well and the rear of the machine can also present an increased hazard when moving in the reverse direction.

[0021] It would therefore be of advantage to allow users to come closer to the rear of a hazard moving in a forward direction, the front of a hazard when moving in reverse or other appropriate side of the hazard before being provided with a warning.

[0022] For sonar-based hazard warning systems a single hazard needs to have at least two transmitting sounders mounted to points on its periphery to calculate orientation to a nearby user. Using prior art approaches the increasing number of sonar transmitting sounders results in increasing round-robin synchronisation cycle transmission times, potentially to the point where range and position information cannot be collated fast enough to provide an effective warning to users. This problem is aggravated further when multiple orientation identifying hazard sounders are deployed in proximity to one another.

[0023] It would be of advantage to have improvements in the field of hazard warning systems which addressed any of the above limitations of the prior art or at least provided the public with an alternative choice. In particular it would be of advantage to have improvements in the field of sonar-based hazard warning systems capable of determining the relative position or orientation of hazards to nearby users without degrading the overallresponse time of the system.

[0024] Disclosure of the Invention

[0025] According to one aspect of the present invention there is provided a hazard mounted warning apparatus configured for engagement with a hazard, the apparatus including at least one sound emitter, and at least one radio signal transmitter, and

[0026] a controller configured to activate the sound emitter and to operate the at least one radio transmitter to transmit a timing signal and a subsequent ranging signal.

[0027] Preferably the hazard mounted warning apparatus includes a radio signal receiver configured to receive at least one delay time signal from a personal warning apparatus carried by a person in proximity to the hazard which the warning apparatus is mounted to, and the controller is configured to calculate a hazard orientation from the received delay time signal or signals.

[0028] Preferably the controller operates the radio signal transmitter to transmit the timing signal and activate the sound emitter at the same time.

[0029] Preferably the controller periodically and repeatedly operates the at least one radio transmitter to transmit timing signals and subsequent ranging signals.

[0030] Preferably the controller is configured to activate the sound emitter to emit a coded sequence of sound pulses and time delays between sound pulses.

[0031] According to a further aspect of the invention there is provided a personal warning apparatus to be carried by a person in proximity to at least one hazard, the apparatus including

[0032] a sound pulse receiver,

[0033] an alarm indicator configured to alert the person carrying the warning apparatus of the presence of a hazard,

[0034] at least one radio signal receiver configured to receive timing signals and ranging signals transmitted by a hazard mounted warning apparatus, acontroller connected to the at least one radio signal receiver and configured to determine a delay time experienced between the receipt of a timing signal and the receipt of a subsequent ranging signal, and to identify two or more hazard mounted warning apparatus which transmitted the ranging signals with the smallest delay times.

[0035] Preferably the controller is configured to identify the ranging signal delay times of two or more hazard mounted warning apparatus which are mounted to the same hazard.

[0036] Preferably the controller is configured to calculate a hazard orientation using the delay times determined for at least two ranging signals transmitted from the same hazard.

[0037] According to another aspect of the invention there is provided a hazard warning system which includes

[0038] a plurality of personal warning apparatus each to be carried by a person as substantially described above, and

[0039] a plurality of hazard mounted warning apparatus substantially as described above, wherein the controllers of each hazard mounted warning apparatus are configured to transmit radio frequency timing signals at the same time and to transmit subsequent radio frequency ranging signals at the same time.

[0040] According to a further aspect of the invention there is provided a method of calculating a hazard orientation to a personal warning apparatus charactered by the steps of:

[0041] • transmitting a radio frequency timing signal from a plurality of hazard mounted warning apparatus

[0042] • receiving the transmitted timing signals at a personal warning apparatus • transmitting a subsequent radio frequency ranging signal from the plurality of hazard mounted warning apparatus

[0043] • receiving the transmitted ranging signals at the personal warning apparatus

[0044] • determining delay times experienced between the receipt of a timing signal and the receipt of a subsequent ranging signal for at least one set of timing and ranging signals transmitted from a hazard mounted warning apparatus• identifying two or more hazard mounted warning apparatus which transmitted the ranging signals with the smallest delay times,

[0045] • calculating a hazard orientation using the delay times determined for at least two ranging signals transmitted from the same hazard.

[0046] According to yet another aspect of the invention there is provided a set of computer executable instructions stored on a computer readable medium arranged for execution by the controller of a personal warning apparatus, the instructions calculating a hazard orientation to the personal warning apparatus by executing the steps of:

[0047] a. receiving a plurality of timing signals transmitted from a plurality of hazard mounted warning apparatus

[0048] b. receiving a plurality of ranging signals transmitted from the plurality of hazard mounted warning apparatus

[0049] c. receiving at least one sound pulse emitted from at least one of the plurality of hazard mounted warning apparatus

[0050] d. determining delay times experienced between the receipt of a timing signal and the receipt of a subsequent ranging signal for at least one set of timing and ranging signals transmitted from a hazard mounted warning apparatus

[0051] e. identifying two or more hazard mounted warning apparatus which transmitted the ranging signals with the smallest delay times, f. calculating a hazard orientation using the delay times determined for at least two ranging signals transmitted from the same hazard.

[0052] According to a further aspect of the invention there is provided a set of computer executable instructions stored on a computer readable medium arranged for execution by the controller of a hazard mounted warning apparatus, the instructions executing the steps of:

[0053] I. transmitting a radio frequency timing signal,

[0054] ii. emitting at least one sound pulse,

[0055] iii. transmitting a subsequent radio frequency ranging signal, iv.

[0056] receiving at least one delay time signal from a personal warning apparatus

[0057] v. calculating a hazard orientation from the received delay time signal or signals

[0058] vi. waiting a delay period and then executing steps (i), (ii) and (iii) again.The present invention relates to the field of hazard warning systems. The invention spans a number of aspects related to the implementation of technology used to provide the required hazard warnings. In various aspects the invention provides a hazard mounted warning apparatus configured for engagement with a hazard in addition to a personal warning apparatus carried by person likely to encounter a hazard. The invention also provides a hazard warning system composed of various apparatus carried by people or mounted to hazards, in addition to methods of operating such apparatus. Also provided are sets of computer executable instructions run by controllers integrated into such apparatus.

[0059] The invention disclosed in this specification allows for the calculation of a hazard orientation in relation to a specific personal warning apparatus.

[0060] Preferably a single common hazard may be used in various embodiments to mount multiple warning apparatus to facilitate this calculation of hazard orientation.

[0061] Reference in general throughout this specification will predominantly be made to the invention being a hazard warning system and / or a hazard warning apparatus mounted to a hazard or carried by a person. Those skilled in the art will however appreciate that the invention also spans the additional aspects referenced above and reference simply to systems or apparatus throughout this specification should in no way be seen as limiting.

[0062] The invention includes or incorporates a hazard mounted warning apparatus in various embodiments. This apparatus is mounted or engaged with a hazard and includes at least one sound emitter and a controller which operates to activate and deactivate the sound emitter.

[0063] The controller of a hazard mounted warning apparatus may be implemented by any appropriate form of programmable logic device or processor. Those skilled in the art will appreciate that a wide range of technologies may be used to implement such a controller such as for programmable gate arrays, application specific integrated circuits and / or general-purpose microprocessors. The processor or controller provided can be loaded with computer executable instructions from a computer readable medium, withthe execution of these instructions again facilitating a method of operating the hazard warning system.

[0064] In preferred embodiments the sound emitter may be provided by various forms of well-known acoustic transducers operable to generate sound waves on demand. The sound emitter employed by the invention may be arranged to emit pulses of sound at select frequencies or within select frequency bands and with a controlled amplitude or power. Those skilled in the art will appreciate that various forms of acoustic transducers well known in the art may be used as sound emitters in accordance with the invention.

[0065] In various embodiments the sound emitter used by the invention may be arranged or operated to emit sound in the ultrasonic range above 20 kHz. In further preferred embodiments such an emitter may be configured or operated to emit sound at approximately 32 kHz. In yet further embodiments such an emitter may be configured or operated to emit sound at approximately 39-41 kHz. Those skilled in the art will appreciate that the invention may be used to emit high-frequency sound and a range of frequencies and may utilise a vibrating diaphragm or any other appropriate form of sound transducer in the implementation of the invention.

[0066] In preferred embodiments a hazard mounted warning apparatus may include a radiofrequency transmitter, preferably connected to and operated by its controller. In such embodiments this R.F transmitter may be operated to transmit a timing signal at the same time as the sound emitter starts to emit a coded sound pulse sequence. The combination of sound and radiofrequency transmissions can then be used by a remote receiving apparatus to measure the transit time of sound from the related hazard.

[0067] In various embodiments the timing signals transmitted by a hazard mounted warning apparatus may include include identity information. This identity information may preferably provide a unique identifier for the apparatus for a hazard mounted warning apparatus when compared with other warning apparatus used in the same location.

[0068] In a further preferred embodiment the identity information for a hazard mounted warning apparatus may also include or allow for the retrieval ofinformation relating to the mounting position of the warning apparatus on a hazard. For example this information may indicate where on a hazard the warning apparatus is mounted to assist in determining an orientation for a hazard. This mounting position information may potentially be encoded into a timing signal, or could be retrieved from a stored location using the unique identity information of the related warning apparatus.

[0069] In additional preferred embodiments a hazard mounted warning apparatus may include two radio signal transmitters. In such embodiments one of these radio transmitters may be dedicated to the transmission of synchronisation signals and the second may be dedicated to the transmission of timing signals and ranging signals. This arrangement allows for the tuning and optimisation of the respective radio transmitters to provide timing and ranging transmissions with different signal characteristics.

[0070] In a further preferred embodiment, a hazard mounted warning apparatus may include a narrowband radio signal transmitter used to transmit a synchronisation signal. This synchronisation signal can be employed in various embodiments to ensure that all hazard mounted warning apparatus in a region operate to transmit their sound pulses at the same time. In such embodiments the hazard mounted warning apparatus may also include an ultra-wide band radio signal transmitter used to transmit a timing and a ranging signal. In such embodiments the narrowband transmitter can provide a synchronisation signal across a narrow range of frequencies while the ultra-wideband transmitter may transmit across a significantly broader frequency range. Narrowband timing signals can easily have information encoded into the signal interpreted coherently by a remote receiver while ultra-wideband signals provide a short-range low-energy transmission nearby receivers.

[0071] In such embodiments a single controller may preferably be configured to control the operation of both the narrowband and ultra-wideband radio signal transmitters. Reference is also made throughout this specification to the invention including a single controller used to operate the narrowband radio signal transmitter and ultra-wideband radio signal transmitter in various embodiments. Those skilled in the art will however appreciate thatother arrangements and configurations of radio transmitters and controllers may also be utilised. For example, in one alternative embodiment a single radio transmitter may be used to transmit both timing and ranging signals if required.

[0072] The invention provides at least one personal warning apparatus carried by a person. This apparatus incorporates a sound pulse receiver capable of detecting the amplitude of received sound pulses and the duration of these received sound pulses. Those skilled in the art will appreciate that any appropriate microphone system or equivalent acoustic transducer may be used to implement such a sound pulse receiver. In various preferred embodiments the sound pulse receiver may provide an output electrical signal representative of both the amplitude and duration of any detected or received sound pulse.

[0073] Again, a personal warning apparatus includes a controller. This controller is arranged to receive at least one signal from the sound pulse receiver which is representative of the sound pulses it receives. This controller can again be implemented by any appropriate form of programmable logic device or processor. Those skilled in the art will appreciate that a wide range of technologies may be used to implement such a controller, such as for example, programmable gate arrays, application specific integrated circuits and / or general-purpose microprocessors. Furthermore, the processor or controller provided can be loaded with computer executable instructions from a computer readable medium, with the execution of the instructions facilitating the method of operating the hazard warning 30 system to be provided.

[0074] A personal warning apparatus incorporates an alarm indicator configured to alert the person carrying the warning apparatus of the presence of a hazard. This alarm indicator may take a variety of forms in various embodiments and can, for example, include an audio warning speaker or warning lights. In additional implementations the alarm indicator may also communicate with remote components or systems to remote users. For example, in some embodiments the alarm indicator may include or communicate with a wireless computer network transceiver to facilitate the transmission of various forms of alarm information to remote users. In such embodimentsthe invention may be configured to provide alerts to this remote user or users in the event of a personal warning apparatus coming into proximity to a specific hazard. This information may be used - for example - to alert the operator of a hazard, stop the operation of adjacent machinery or stop the motion of a vehicle.

[0075] Reference in general is made throughout this specification to the various components of a hazard mounted warning system or a personal warning system being deployed together, preferably at the same location or within a common housing. However, in various embodiments well know communications and information technology may facilitate implementation of a distributed architecture with - for example - cloud computing technology used to implement various processors or controllers. Furthermore, an alarm indicator provided by a personal warning system may also include remote components used - for example - to alert operators of various machinerybased hazards to the proximity of a person and could also include components arranged to disable the operation of such hazards.

[0076] In preferred embodiments a personal warning apparatus may include a radiofrequency receiver, preferably connected to and able to supply signals to its controller. In such embodiments this RF receiver may be used to receive a timing signal transmitted from a remote hazard at the same time as a coded sound pulse sequence is emitted from this hazard. The combination of sound and radiofrequency transmissions can then be used by the processor of the personal warning apparatus to measure the transit time of sound from the related hazard.

[0077] In preferred embodiments a personal warning apparatus may incorporate a single radiofrequency receiver which is arranged to receive both timing signals and ranging signals transmitted from a remote hazard at different times. In further preferred embodiments the single radio frequency receiver may be configured to receive an initial ultra-wideband radiofrequency transmission as a timing signal, and a subsequently transmitted ultra-wideband transmission as a ranging signal.

[0078] As indicated above additional aspects the invention provides a method which allows for the calculation of a hazard orientation in relation to a specificpersonal warning apparatus. This method utilises radiofrequency timing and ranging signals transmitted from hazards, where ranging

[0079] signals are transmitted separate to and at different times to timing signals. This aspect of the invention can find particular utility in situations where a hazard is moving and its orientation to a personal warning apparatus changes over time.

[0080] This method may operate by a hazard mounted warning apparatus initially transmitting a timing signal to be received by personal warning apparatus. A ranging signal is then transmitted from a hazard and received by the personal warning apparatus. A controller associated with the personal warning apparatus can then determine a delay time between the receipt of a timing signal and the receipt of a subsequent ranging signal transmitted from the same hazard. Preferably all hazard mounted warning apparatus in a location may have their operations synchronised so that they all transmit timing signals at the same time and their subsequent ranging signals are all transmitted at the same later time. The receiving personal warning apparatus can then determine a delay time for specific sets of timing and ranging signals, with nearby hazards having smaller delay times than more remote hazards.

[0081] With this method of operation appropriate sets of computer executable instructions may be run by each hazard mounted warning apparatus and personal warning apparatus. Preferably the controller involved may be programmed so that a hazard mounted warning apparatus transmits a timing signal and activates its sound emitter at approximately the same time. Due to the comparatively low speed of sound to light a personal warning apparatus is able to receive the paired set of timing and ranging signals transmitted from the same hazard before any related sound pulses. The personal warning apparatus therefore has the ability to associate a specific delay time with a received sound pulse or pulses. The delay times which are determined using timing and ranging signals need not necessarily be used to provide an accurate or precise measurement of distance between a hazard and personal warning apparatus but instead can provide range approximations used simply to identify an apparatus mounted to a nearby hazard.Preferably the specific delay times determined through this method may each be associated with or correlated to a specific hazard mounted warning apparatus. In preferred embodiments two or more of such warning apparatus may be mounted to the same common hazard at various points around the perimeter, sides or faces of the hazard.

[0082] This arrangement allows for the calculation of a hazard orientation. By using prior knowledge of the specific mounting positions used around the perimeter of a hazard small differences in delay time can be used to determine which side, face, or region of a hazard is orientated closest to the personal warning apparatus. The related delay times for each warning apparatus mounted to a common hazard may be stored in an ordered format or data structure based on increasing or decreasing delay time, with this order being used to calculate a hazard orientation.

[0083] In a preferred embodiment a hazard orientation may be calculated with the use of a lookup table. This table may store entries for all possible order combinations of delay times for the warning apparatus mounted to a specific hazard. This table can preferably correlate a resultant hazard orientation value to each specific order of received delay times.

[0084] In a further preferred embodiment, the delay times used in the calculation of a hazard orientation may be compiled using a rolling average of previously received delay times. In such embodiments the rolling average of delay time use may mitigate the impact of transient noise or random error effects.

[0085] In a preferred embodiment the invention may use two hazard mounted warning apparatus only in the determination of a hazard orientation. In such embodiments these components may be mounted to - for example - the centre front and centre rear of a hazard. This arrangement finds particular utility when the hazard involved is capable of forward movement and where the front of the hazard normally is a greater danger than the rear. However, mobile hazards which can move in a reverse direction can also result in greater danger from the rear of the hazard when moving in reverse. An ordered list of delay times for each of these three warning apparatus may therefore be used to determine if the front of the hazard is orientatedtowards a personal warning apparatus or if the rear is orientated towards the same personal warning apparatus.

[0086] Reference throughout this specification is also made to the invention using a set of two hazard mounted warning apparatus engaged with the same common hazard which is to have its orientation determined. Those skilled in the art will however appreciate that different numbers and potentially three, four or more hazard mounted warning apparatus may also be used in conjunction with a single hazard if required.

[0087] For example, in some embodiments the invention may use three hazard mounted warning apparatus in the determination of the hazard orientation. The provision of additional warning apparatus with a hazard increases the complexity or resolution of the hazard orientation information which can be determined in combination with the present invention. In one instance these components may be mounted to the front left, front right and centre rear of a mobile hazard for example, allowing for the definition of different shapes of zones of interest around a hazard, potentially depending on hazard orientation and direction of travel of the hazard.

[0088] Those skilled in the art will also appreciate that the calculation of a hazard orientation may be undertaken in a number of ways in different embodiments.

[0089] For example, in some instances hazard orientation may be calculated by the controller of a personal warning apparatus which determines the required input set of delay times. The controller in this instance may be programmed with information related to the identities and mounting positions of various warning apparatus mounted to nearby hazards.

[0090] In additional embodiments of the invention a personal warning apparatus may include a radio signal transmitter which is arranged to transmit at least one delay time signal to radio signal receivers provided in combination with each hazard mounted warning apparatus. On receipt of such a delay time signal or a series of delay signals the controllers provided with the hazard mounted warning apparatus can similarly determine the orientation of their hazard to a nearby personal warning apparatus. In further preferredembodiments the controller may be programmed to disable the operation of a hazard if the hazard is moving towards a personal warning apparatus and / or the hazard is determined to be inside a minimum safe distance to the personal warning apparatus.

[0091] In further preferred forms of such embodiments a personal warning apparatus may be arranged to transmit a single delay time radio signal which incorporates information relating to multiple delay times associated separate hazard mounted warning apparatus. This single delay time signal can therefore provide all the information required to calculate a hazard orientation

[0092] However, those skilled in the art will appreciate that in other implementations a personal warning apparatus may transmit multiple delay time radio signals to hazard mounted warning apparatus if required. In such embodiments each radio signal may incorporate a delay time associated with identity information for a particular hazard mounted warning apparatus.

[0093] Those skilled in the art will also appreciate that hazard orientation calculated with the invention may be used in various ways by the component elements of a hazard warning system.

[0094] For example, in the case of a personal warning apparatus the calculated hazard orientation can then be used by its controller to determine if and how a related personal alarm indicator should be activated. In various embodiments the control of a personal warning apparatus may increase a minimum distance required to trigger an alarm indicator if the front of a hazard is orientated towards the personal warning apparatus. Similarly, this alarm triggering distance may be reduced if the rear of the hazard is orientated towards the personal warning apparatus. In further embodiments the minimum distance required to trigger an alarm indicator may also be reduced if successive delay time measurements indicate that the hazard is moving towards the related personal warning apparatus.

[0095] This hazard orientation information may also be used by the components engaged with a hazard. Again, in various embodiments the trigger conditionsfor warning indicators or control systems associated with a hazard may depend on the related hazard orientation. For example, in

[0096] one instance drive power to the wheels of the moving hazard may be disabled if the front of the hazard is orientated towards a personal alarm indicator, the hazard is currently moving forward and the hazard is determined to be within a minimum safe distance. The minimum safe distance used may be smaller when the rear of a moving hazard is orientated towards a personal warning apparatus and the hazard is stationary or moving forward. Conversely the minimum safe distance used may be larger when the rear of a moving hazard is orientated towards a personal warning apparatus and the hazard is moving backwards.

[0097] Brief description of the drawings

[0098] Additional and further aspects of the present invention will be apparent to the reader from the following description of embodiments, given in by way of example only, with reference to the accompanying drawings in which:

[0099] • Figure 1 provides an exemplary layout sketch of an arrangement of a personal warning apparatus in proximity to multiple hazard mounted warning apparatus,

[0100] • Figure 2 provides a table representing the digital formulation of a radio frequency signal and a radio frequency ranging signal as transmitted by hazard mounted warning apparatus and as received by the personal warning apparatus of figure 1 in accordance with an embodiment,

[0101] • Figure 3 provides tables representing the timing of the timing and ranging signals of figure 2 as transmitted and as received by the

[0102] hazard mounted warning apparatus and personal warning apparatus of figure 1, and

[0103] • Figure 4 provides an exemplary layout sketch of a moving hazard provided with three hazard mounted warning apparatus and a coordinate system used to define a hazard orientation for the hazard shown.

[0104] Further aspects of the invention will become apparent from the following description of the invention which is given by way of example only of particular embodiments.Best modes for carrying out the invention

[0105] Figure 1 Figure 1 provides an exemplary layout sketch of an arrangement of a personal warning apparatus P, and hazard mounted warning apparatus Hl, H2, H3 and H4. In the arrangement shown the personal warning apparatus P is worn by a person to be warned. The distances between each hazard and the personal warning apparatus P are shown respectively 15 as dl, d2, d3 and d4. Hazard Hl is closest to personal warning apparatus P, followed by H2, then H3 and hazard H4 is the furthest away. Distance dl is therefore the shortest distance and distance d4 is the largest.

[0106] Figure 2 provides a table - reproduced below - which represents as an example the digital formulation of a radio frequency timing signal and a radio frequency ranging signal. These signals are transmitted by the hazard mounted warning apparatus and received by the personal warning apparatus of figure 1 in accordance with a preferred embodiment.

[0107] Timing signal

[0108]

[0109] Ranging signal

[0110]

[0111] The header portion of each signal is the same across all hazards and for both the timing and ranging signals. This header is used to identify the specific hazard warning system which contains all nearby morning apparatus. Thepayload section of each segment uniquely identifies each of the transmitting hazards Hl through H4.

[0112] Figure 3 provides tables - reproduced below -representing the timing of the timing and ranging signals of figure 2 as transmitted and as received by the hazard mounted warning apparatus and personal warning apparatus of figure 1.

[0113] The first table represents the synchronous transmission of timing signals t and ranging signals r from each of the hazards H1-H4. As can be seen from this table the operation of each hazard mounted warning apparatus is synchronised across the system shown in figure 1. As can also be seen each hazard mounted warning apparatus transmits its timing signal at approximately the same time as it starts to emit sound pulses S.

[0114] Signal transmission times from H1-H4

[0115]

[0116] The second table represents the receipt timing of the same timing and ranging signals by the personal warning apparatus of figure 1.

[0117] Ranging signal reception times from H1-H4

[0118]

[0119]

[0120] As can be seen from the above table the processor of the personal warning apparatus can readily determine that hazard Hl has the shortest delay time for its ranging signal. This processor then operates to focus only on the sound pulses S emitted by hazard Hl.

[0121] As would be appreciated by those skilled in the art the hazard warning system in practice may use calculations based on two distinct signal propagation or delay times. With prior art based systems, a sonar-based range value may be calculated at the personal warning apparatus from the receipt time of the related radio frequency timing signal t subtracted from the receipt time of sonar pulses S. This sonar-based range calculation preferably provides an accurate reliable range value for a personal warning apparatus to a hazard. The invention also utilises a radiofrequency-based delay value calculated from the receipt time of the related radio frequency timing signal t subtracted from the receipt time of the radio frequency ranging signal r. This radio frequency-based signal propagation delay time can be obtained very quickly and need not be particularly accurate as it is preferably employed just to isolate and identify the nearest hazard to a personal warning apparatus.

[0122] Figure 4 provides an exemplary layout sketch of a moving hazard provided with three hazard mounted warning apparatus.

[0123] In the circumstances shown a moving hazard is provided by a forklift with a series of warning apparatus mounted to its perimeter at its front right (A), front left (B) and rear (C). Shaded regions illustrated extending from the forklift identify areas of concern where warnings are to be provided if a person is present.

[0124] Figure 4 also shows a co-ordinate system used to define a hazard orientation for the hazard shown.In the embodiment illustrated each of the hazard mounted warning apparatus A, B, C is configured to receive delay time signals transmitted from a nearby personal warning apparatus (not shown). These delay time signals are generated by the personal warning apparatus using the approach as discussed for the invention in relation to Figures 2 and 3. In the embodiment represented in respect to figure 4 each hazard mounted warning apparatus receives delay time signals related to the timing and ranging signals sent respectively by each apparatus A, B and C.

[0125] The controller provided in each apparatus is loaded with the following lookup table which it uses to calculate a hazard orientation to the related personal warning apparatus. As can be seen from the table below the delay times are ordered in relation to the shortest delay time first are combined with the identity of the related warning apparatus. The sequence at which these delay times are order therefore dictates the hazard orientation being calculated.

[0126]

[0127] In the embodiment shown the forward-facing shaded warning areas extended further from the forklift hazard than the equivalent areas extending to the rear. Each of the morning apparatus A, B, C can operate control systems to disable the forward motion of the forklift if a person is determined to be inside either of these shaded areas. This action will be triggered when a person is further away from the front of forklift than the rear of the forklift and the forklift is moving forwards.

[0128] Those skilled in the art will appreciate that similar functionality or performance may also be achieved in alternative embodiments through the use of two hazard mounted warning apparatus only. For example, in one alternative embodiment these two components may be used to identify a front hazard orientation and a rear hazard orientation only. Conversely theuse of more components mounted to a hazard can provide higher resolution of hazard orientation, potentially around the front of a mobile hazard while also providing for more complex high-resolution hazard orientation information.

[0129] It is to be understood that the present invention is not limited to the embodiments described herein and further and additional embodiments within the spirit and scope of the invention will be apparent to the skilled reader from the examples illustrated with reference to the drawings. In particular, the invention may reside in any combination of features described herein or may reside in alternative embodiments or combinations of these features with known equivalents to given features. Modifications and variations of the example embodiments of the invention discussed above will be apparent to those skilled in the art and may be made without departure of the scope of the invention as defined in the appended claims.

Claims

What we claim is:

1. A personal warning apparatus to be carried by a person in proximity to at least one hazard, the apparatus includinga sound pulse receiver,an alarm indicator configured to alert the person carrying the warning apparatus of the presence of a hazard,at least one radio signal receiver configured to receive timing signals and ranging signals transmitted by a hazard mounted warning apparatus,a controller connected to the at least one radio signal receiver and configured to determine a delay time experienced between the receipt of a timing signal and the receipt of a subsequent ranging signal, and to identify two or more hazard mounted warning apparatus which transmitted the ranging signals with the smallest delay times.

2. The personal warning apparatus of claim 1 wherein the controller is configured to identify the ranging signal delay times of two or more hazard mounted warning apparatus which are mounted to the same hazard.

3. The personal warning apparatus of claim 1 or claim 2 wherein the received timer signals include identity information for a hazard mounted warning apparatus4. The personal warning apparatus of claim 3 wherein identity information for a hazard mounted warning apparatus provides information relating to the mounting position of the warning apparatus on a hazard.

5. The personal warning apparatus of any one of claims 1 to 4 wherein the delay times are compiled using a rolling average of previously received delay times.

6. The personal warning apparatus of claim any one of claims 2 to 5 wherein the related delay times for each warning apparatus mounted to a common hazard are stored in an ordered data structure based onincreasing or decreasing delay time where this order is used to calculate a hazard orientation.

7. The personal warning apparatus of claim 6 wherein a hazard orientation is calculated using a lookup table.

8. The personal warning apparatus of as claimed in any one of claims 1 to 7 wherein the controller increases a minimum safe distance required to operate the alarm indicator if the front of a hazard is orientated towards the personal warning apparatus.

9. The personal warning apparatus of claim 8 wherein the controller increases a minimum distance required to operate the alarm indicator if the hazard is moving towards the personal warning apparatus.

10. The personal warning apparatus of claim as claimed in any one of claims 1 to 9 wherein the controller decreases the minimum distance required to operate the alarm indicator if the rear of a moving hazard is orientated towards a personal warning apparatus11. The personal warning apparatus of claim 10 wherein the controller increases a minimum distance required to operate the alarm indicator if the hazard is moving towards the personal warning apparatus.

12. The personal warning apparatus of any one of claims 1 to 11 which includes a radio signal transmitter arranged to transmit at least one delay time signal to radio signal receivers provided in combination with each hazard mounted warning apparatus.

13. The personal warning apparatus of any one of claims 1 to 12 which includes an alarm indicator incorporating an audio warning speaker or warning lights.

14. The personal warning apparatus of any one of claims 1 to 13 which includes an alarm indicator which communicates with a remote component to provide warnings of hazards to remote users.

15. The personal warning apparatus of any one of claims 1 to 14 wherein the radio frequency receiver is configured to receive an initial ultra- wideband radiofrequency transmission as a timing signal, and a subsequently transmitted ultra-wideband transmission as a ranging signal.

16. A hazard mounted warning apparatus configured for engagement with a hazard, the apparatus includingat least one sound emitter, andat least one radio signal transmitter, anda controller configured to activate the sound emitter and to operate the at least one radio transmitter to transmit a timing signal and a subsequent ranging signal, anda radio signal receiver configured to receive at least one delay time signal from a personal warning apparatus carried by a person in proximity to the hazard which the warning apparatus is mounted to, wherein the controller is configured to calculate a hazard orientation from the received delay time signal or signals.

17. The hazard mounted warning apparatus of claim 16 wherein the controller is programmed to disable the operation of a hazard if the hazard is moving towards a personal warning apparatus or the hazard is determined to be inside a minimum safe distance to the personal warning apparatus.

18. The hazard mounted warning apparatus of claim 16 or claim 17 wherein the controller periodically and repeatedly operates a wide band radio signal to transmit the timing and ranging signals and operates a narrowband radio signal transmitter to transmit a synchronisation signal.

19. A hazard warning system which includesa plurality of personal warning apparatus each to be carried by a person as claimed in claim 1, and a plurality of hazard mounted warning apparatus as claimed in claim 16, wherein the controllers of each hazard mounted warning apparatus are configured to transmit radio frequency timing signals at the same time and to transmitsubsequent radio frequency ranging signals at the same time.

20. A set of computer executable instructions stored on a computer readable medium arranged for execution by the controller of a personal warning apparatus as claimed in any one of claims 1 to 15, the instructions calculating a hazard orientation to the personal warning apparatus by executing the steps of:a. receiving a plurality of timing signals transmitted from a plurality of hazard mounted warning apparatusb. receiving a plurality of ranging signals transmitted from the plurality of hazard mounted warning apparatusreceiving at least one sound pulse emitted from at least one of the plurality of hazard mounted warning apparatus determining delay times experienced between the receipt of a timing signal and the receipt of a subsequent ranging signal for at least one set of timing and ranging signals transmitted from a hazard mounted warning apparatuse. identifying two or more hazard mounted warning apparatus which transmitted the ranging signals with the smallest delay times,f. calculating a hazard orientation using the delay times determined for at least two ranging signals transmitted from the same hazard.

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