(0001] This invention relates in general to a climber on a ladder of any practical length using a means of support for a portion of the climber's weight during ascent and descent on the ladder using wireless communications, and in particular improvements to extend the range of operation.

BACKGROUND OF THE INVENTION

[0002] US Patent No. 8,141,681 discloses a method for providing a substantially vertical ladder ascent and descent device characterized by an endless loop belt to which a climber may attach, a load measuring sender apparatus or personal control apparatus (PCA), to measure the amount of load the climber exerts on the belt, a wireless link to send climber load information to a remote receiver, and a motor driving the belt that is controlled by the information received by the receiver. By this means the climber may be dynamically supported by a specified amount of body weight relief, thereby making ascent and descent significantly easier as the climber need only provide energy in climbing for reduced apparent body weight.

[0003] US 8,141,681 is suitable for operation over relatively short distances, for example less than 100m and does not anticipate operation over long distances in a shaft such as may be found in mining, underground and long distance applications, for example greater than 500m, including in a nominally vertical rescue shaft which includes an escape ladder, and where radio signal loss is significant over the large distances experienced in underground applications, thereby rendering radio communication methods generally infeasible. Known methods of increasing range such as leaky coax, higher power transmission, wireless repeaters and coaxial cables all have a combination of high signal loss, complexity or high cost issues and so are not regarded as commercially feasible.

[0004] EP 2542750 Al discloses a means of providing remote control of a climb assist motor and also does not anticipate operation over long distances. EP 2542750 Al is typical of a crane control type application where a wireless PCA is used to control up and down directions, start, stop, support level or motor torque, or any combination of these selectable parameters. Such means of providing support generally does not include dynamically adjustment of support based on direct climber load measurement, but may include motor torque management using measurement of motor current or power.

[0005] US 2009/021 1846 discloses a belay device which allows support of a climber and a wireless control device to start and stop the system, or to set a mode of operation, again similar to crane control types'of operation referred to above.

[0006J None of the disclosures cited provide ladder climbing devices which are capable of underground, long distance or non line-of-sight operation.

[0007J It is known that where people who are not fit or lack the muscular strength and training to climb a ladder, may not be able to climb beyond relatively short distances, for example 50m. If unfit persons attempt to climb beyond this distance without taking frequent rests or being provided with assistance, they may perhaps suffer muscular strain or a debilitating injury. It is noted that many of the workers in modern mines who are no longer substantially active, being relatively passive machine operators rather than physically active miners.

[0008] Of course, an elevator device may be installed. However these are v ery expensive, and may be subject to onerous standards and other safety and rigorous maintenance requirements which cause a high on-going maintenance cost.

[0009] In some instances, the ladder may be within an escape shaft within a mine and may be more than 500m long. Additionally there may be many people who require use of the ladder to escape in an emergency. Consequently it is desirable that reliable support and climber-managed assist is provided to ensure that each person may complete the climb with reduced physiological trauma and in a timely manner.

[0010] Also, it is useful for the weight of the PCA associated with the climber to be relatively small, and as a consequence, with limited energy being available to allow long periods of continuous use, for example from a lightweight battery. This energy limitation may also limit the available PCA operating power. Consequently, the signal strength of signals transmitted from the PCA are low so as to ensure long operating battery life to ensure completion of one or more climbs. This leads to relatively low radio range between the PCA and receiver.

[0011] Where the radio range over which wireless link is of a distance such that the signal power from the PCA reaching the receiver is below a reliably detectable threshold, then control of the motor driving the endless belt loop may be lost and the benefit of support to the climber also lost.

[0012] Additionally, the loss characteristics for signal transmission in a shaft may be significant, for example approximately -ldBm per meter as discovered during tests in a mine as depicted in Figure 3A herein, and cause wireless signals to be attenuated below a specified detection level within, for example, 50m. Also factors related to multi-path fading and signal polarization may also adversely affect maximum radio range.

[0013] A further factor contributing to low received signal strength is that line of sight operation cannot be assumed as the shaft may exhibit curvature or other obstructions to line-of sight and straight line signal propagation.

[0014] An object of the present invention is to provide an improved ladder climbing device which overcomes at least some of the disadvantages of the prior art and enables significantly extended range of operation.

SUMMARY OF THE INVENTION

[0015] According to the present invention there is provided a system for assisting generally vertical ascent or descent of a climber on a ladder structure, the system including:

(i) a continuous belt located generally adjacent to the ladder structure;

(ii) drive means for driving the belt;

(iii) coupling means for coupling the climber to the belt;

(iv) signal generating means for generating drive control signals;

(v) a communication system; and

(vi) a control system responsive to the communication system for controlling the operation of drive means so that belt assists the climber ascending or descending the ladder structure and wherein;

(vii) the communication system includes: (a) a plurality of receivers, each of which is mounted at a predetermined position along the ladder structure and is responsive to the drive control signals generated by the signal generating means; and

(b) a communications link to which each of the receivers is coupled whereby said drive control signals or signals derived therefrom are communicated to the control system.

[0016] The effective length and capacity may be increased by having a number of vertically arranged stages each including a system as defined above.

[0017] Alternatively, the capacity of the system can be increased by having a number of systems, as defined above, arranged in other spatial relationships, for example side by side.

[0018] Embodiments of the invention can be used with ladders inside an escape shaft within a mine or associated with other industrial structures and may encompass distances of 500m or more. The system of the invention ensures that the assist system continues to operate independent of the climber's position on the ladder relative to the motor controller and ensures continuity of assistance throughout the climb to reduce fatigue and enhance the safety of the climber when applied to such extensive climbs. Of course, the methods and systems disclosed herein may be applied to many other fields of use including rock climbing, building escape, rescue methods, or any other application requiring substantially vertical transport of a person.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The invention will now be further described with reference to the accompanying drawings in which:

FIG. 1 discloses a schematic view of a lifting system including general arrangement of the system according to the invention;

FIG. 2 discloses a further model of the general arrangement according to the invention;

FIG. 3 discloses a model of Received Signal Strength Indication, hereinafter represented as RSSI, as the PCA moves within the shaft;

FIG. 3 A discloses a measurement of RSSI versus radio range; FIG. 4 discloses a circuit block diagram of one possible representation of a receiver according to the invention;

FIG. 4A discloses a diagram of one possible representation of a display according to the invention;

FIG. 5 discloses a circuit block diagram of one possible representation of a master receiver according to the invention;

FIG. 6 discloses a description of a preferred messaging structure according to the invention;

FIG. 7 discloses a flow chart of operation of the master receiver according to the invention;

FIG. 8 discloses a flow chart showing further details of the operation of the master receiver according to the invention;

FIG. 9 discloses a flow chart of operation of a receiver according to the invention, and;

FIG. 10 discloses a further general arrangement of multiple systems according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0020] Figure 1 shows a lifting system 1 constructed according to the invention. In this arrangement the lifting system 1 is installed in a shaft 18 and includes a ladder or ladder-like apparatus 2, an assist motor 3 which drives a sheave (not shown) at the proximal end of the ladder controlled by a controller 4, an idler sheave 8 at the distal end of the ladder, and an endless belt 7 arranged between the sheaves. A typical belt may be formed from a kernmantle rope such as is used for rock climbing, or preferably from a thermoplastic copolyester elastomer with a polyester fibre centre and, for example, a breaking strength of 450kg It will be appreciated that the belt could be replaced by a cable, chain or the like and therefore in this specification the word belt should be broadly construed to embrace these alternatives. Many of the individual components of the invention are similar to those disclosed in the aforementioned US Patent No. 8,141,681 and the contents of that patent specification are incorporated herein by reference.

[0021] Further, a climber 5 wearing a safety harness (not shown) preferably with a front "D" ring is connected to the belt 7 by a rope grab 6 such that the climber is able to receive support from the belt 7 during climbing of the ladder 2.

[0022] Preferably, a controlling device includes a wireless personal control apparatus (PCA), referred to as the PCA 9, which can be of a type commercially available from SafeWorks, LLC, USA. The PCA 9 can be interposed between the harness D ring and the rope grab 6 connected to the belt 7, or is separately available to the climber during the climb. The PCA has the functionality to set direction of a pending climb, start or stop a climb, optionally measure the level of support experienced by the climber, or any combination thereof, and generate control signals which are communicated to the controller 4 and utilised for drive control of assist motor 3.

[0023] In the illustrated arrangement the PCA 9 periodically, for example 5 to 8 times per second, or upon manual command, sends a message to the controller such that the operation of the motor 3 is controlled to maintain the tension in the belt 7 at the point of attachment of the rope grab 6 nominally at a specified value, thereby providing the climber with support and commensurate weight relief. Such support may be either dynamically adaptive to maintain approximately constant weight relief independent of climber climb speed, or provide an approximately constant speed rate of climb for loads below a maximum value. Typically the tension of level of support is in the range 25 kg to 50kg, and ideally selectable by the climber 5 for the climber's preferred degree of comfort, but preferably not greater than the climber's body weight.

[0024] To further expand on the above, various methods for message or signal generation by the PCA for the purpose of managing the motor operation to provide support to the climber include in any combination:

(i) sensing the load applied to the belt 7 by the climber 5 to maintain an approximately constant level of support, exemplified by US 8,141 ,681 ;

(ii) operating a switch or button (not shown) by the climber so that the drive control signals turn the motor 3 oh or off thereby starting or stopping a climb exemplified by US 8,141 ,681 and EP 2542750;

(iii) operating a switch or button (not shown) by the climber 5 so that the drive control signals cause the torque or force applied by the motor 3 to the belt 7 to be settable according to the climber's requirement for the level of support, for example by using feedback control at the motor 3 to maintain a set level of motor current or power exemplified by and EP 2542750;

[0025] It is noted that in this specification, where the term PCA is used, this also includes any climb management apparatus such that the climber may remotely direct the activity of the assist motor 3.

[0026] As best seen in Figure 2, the system 1 of the invention includes a communication system 14 which includes a master receiver 10 coupled to a plurality of receivers 12 by means of a communication cable 16. Optionally master receiver 10 may not include a wireless receiver as it may be located in a position where wireless signals may not be receivable. Each of the receivers 12 includes an antenna 1 1 which may optionally be included within the packaging of receivers 12. As will be described in more detail below, the receivers 12 are distributed in the shaft 18 so that they are always in a position in which at least one can receive control signals generated by the PCA 9. As shown in Figures 1 and 2, the communication system 14 includes a coupling 17 to couple output from the master receiver 10 to the controller 4.

[0027] Because the shaft 18 may extend many hundreds of meters, and may not necessarily be straight, distribution of the receivers 12 throughout the shaft 18 is required since the signal loss of signals transmitted by the PCA 9 to the receivers 12 may be below receiver 12's detection threshold where distance between the PCA and the receiver exceeds a maximum value, typically 50m. Typically the PCA 9 includes a battery powered radio transmitter operating in the well known ISM band and is arranged to be capable of transmitting a power in the range of 0 (zero) dBm for a duration, for example 24 hours, which is sufficient to enable a climber or multiple successive climbers to span the reach of the ladder structure. Typically the battery would have a capacity of at least 700 mAhr. The maximum allowed transmitting power is determined by the relevant regulations governing radiating devices.

[0028] Typically signal loss is of the order of -ldB per metre. Obviously different shaft structures could result in more or less loss, but the figure quoted is typical of a polypropylene lined concrete or rock shaft with a moulded-in ladder. It is also necessary to allow for the significant inefficiency of transmitter antenna (not shown) incorporated into the PCA 9, leading to an effective radiated power typically of -50dBm. With a - lOOdBm receiver sensitivity for the receivers 12, the radio range of operation becomes typically 50m and therefore the spacing of the receivers 12 is required to be no more than nominally 100m. Consequently the provision of multiple receivers 12 in the shaft 18 ensures adequate reception throughout the length of the shaft, and therefore the number and disposition of the receivers 12 is then dependent on the length and geometry of the shaft.

[0029] For example, based on the radio range described above and allowing that the master receiver 10 does not include the wireless receiver, distances Dl at the top and bottom of the shaft 18 may be reasonably specified as 50m or less, and distances D2 between the intermediate receivers at 100m or less. In Figure 1 four receivers 12 are shown corresponding to a shaft, nominally 400m long. Of course more or less than four the receivers 12 may be deployed, the minimum number being determined by the length and geometry of the shaft 18.

(0030] In Figure 2 the master receiver 10 is positioned proximal to the controller 4. Alternatively, the master receiver 10 may be incorporated into the controller 4. For convenience, the coupling 17 can be a cable which carries a radio frequency signal to match the signal requirements of a commercially available type of controller 4. However, depending on the signal input requirements of the controller, and as is well known, the coupling 17 may be replaced by other methods, for example but not necessarily twisted pair wires, optical, wireless or other means.

[0031] In the arrangement shown in Figure 2, the master receiver 10 includes a power supply for distributing operating power to the receivers 12 within the shaft, for example at a level of 48V DC or AC via the cable 16. Of course it is equally feasible to provide power in alternative ways, and not necessarily sourced by master receiver 10.

[0032] The wireless signal frequency generated by the PCA 9 may be selected from many values, but for convenience of equipment size and practical propagation considerations, a frequency in the 800MHz to 1000MHz is preferred, according to country frequency allocation and EMC regulations, for example at the frequency allocation for the ISM band. Another choice may be in the 2.4GHz band, although signal losses in the shaft may be higher.

[0033] The antennas 11 could, for example, comprise a ¼ wave whip or a higher gain type, such as a Yagi. Where a directional antenna is deployed, the receivers 12A and 12C near the top and bottom of the shaft 18 respectively may operate with antennas 1 1 pointing down and up respectively, whereas the intermediate receivers 12B may have back-to-back antenna arrangement to ensure adequate sensitivity with the PCA 9 at maximum range, that is, with the PCA approximately at the mid point between the receivers. To reduce mismatch and loss, as is known, a signal combiner may be included with such back-to-back antennas. For example a Wilkinson combiner may be used as is well known.

[0034] For convenience, power to the receivers may be included in cable 16 as mentioned above. The cable 16 may be a multi-wire cable which connects between the master receiver 10 and all the receivers 12, and may include power supply wires separate from the communications wires. Preferably twisted pair cables are used to reduce susceptibility to interfering signals. The cable 16 preferably carries a digital representation of the signal received by receivers 12 as emitted from the PCA 9, although an analog signal may alternatively be communicated on the cable. Functionally, each of the receivers 12 forwards the signal received from the PCA 9 and an estimate of RSSI whenever polled by the master receiver 10. The RSSI value is an estimate of the signal power level incident at the respective receivers 12. At the point the receiver 12 gains sync with the incident signal from the PCA 9, the level of the received signal is preferably converted to a dB level representing RSSI.

[0035] For convenience and reliability of data transmission on the cable 16, the well known RS485 protocol may be used including full or half duplex methods. Alternative protocols may be implemented such as RS232. Preferably the communication system 14 operates as a wired polled network wherein the master receiver 10 sequentially polls attached slaves (the receivers 12) and maintains overall control of the network.

[0036] Another alternative to providing separate power supply and signal wires to the respective receivers 12 utilises modulating of the power line level as is well known to represent the signal. Such a method may only require a two wire cable 16. As a further alternative, non-polled methods such as time-division multiplexing as is well known may be employed to communicate signals between receivers 12 and master receiver 10.

[0037] In one mode of operation, the management circuitry within the master receiver 10 sequentially addresses the receivers 12 to collect recent signal information received from the PCA 9. Obviously if the PCA 9 is out of range of a receiver 12, then the level of signal will be low at that receiver, for example below -lOOdBm, and no signal is reliably detected at the receiver 12.

[0038] The RSSI value is dependent on the spacing between adjacent receivers 12 and the PCA 9. Consequently, to maintain effective connection between the PCA and the controller 4, the receivers should be spaced such that the RSSI preferably does not reach values approaching the minimum sensitivity of the communication system 14.

[0039] Once all receivers have been polled by the master receiver 10, then preferably the signal with the highest RSSI value is recognized by the master receiver 10 and sent to the controller 4 to be used to control the assist motor 3.

[0040] In accordance with a further aspect of the invention, where a shaft or structure exhibits discontinuities such as a change in direction rendering parts of the shaft out of line-of-sight, the receivers may be located at positions to compensate for any discontinuities thereby ensuring continuous wireless coverage within the shaft. In other words, the distribution of the receivers 12 within the shaft 18 can be selected so as to provide optimum performance of the communication system 14.

[0041] In accordance with another aspect of the invention, it is possible to arrange for the communication system 14 to monitor RSSI received from the respective receivers 12 and to estimate the position of the PCA 9. This thereby enables monitoring of the approximate position of the climber 5 who is proximal to PCA 9 within the shaft 18 by a system operator having access to the master receiver 10.

[0042] Figure 3 diagrammatically represents the value of RSSI at successive receivers 12 along the length of the shaft 18 as a climb proceeds. Where RSSI is expressed in dB then there is an approximately linear change in signal strength as a function of distance along the shaft 18. This is diagrammatically illustrated in Figure 3A which shows the relationship between distance (that is, radio range) and RSSI is approximately linear. This data was obtained by measurements from an operating PCA in a granitic shaft. The vertical axis shows the RSSI value and the horizontal axis shows the radio range between the receiver and PCA. It is seen that the rate of signal reduction with distance is about -0.9dB/m, for convenience herein represented as -1 dB/m.

[0043] In accordance with this aspect of the invention, an algorithm for intrinsic estimation of the approximate position of the climber 5 uses the increase or decrease of signal strength as the PCA moves toward or away respectively from a particular receiver. Other structures related to the shaft may cause varying rates of change with position but the algorithm nevertheless provides a useful estimate of position.

[0044] In the exemplary arrangement of Figure 3 with three receivers 12 and the PCA within a distance of 250m from receiver 12A and spacing between receivers as shown with receiver 12A at the proximal end of the shaft and receiver 12C within 50m of the distal end of the shaft, then using the value of RSSI from each of the receivers, the approximate position d of the PCA 9 from receiver may be estimated by the following procedure:

If Max(RSSl _A ,B,c) > -1 0 then (a valid signal is available from any receiver);

If Max(RSSI _A .B,c) = RSSI _A then 0<d<50 (the strongest RSSI is from receiver A); If Max(RSSI _A ,B,c) = RSSI _B then 50<rf< 150 (the strongest RSSI is from receiver B); If Max(RSSI _A ,B,c) = RSSI _C then d> 150m (the strongest RSSI is from receiver C); Else d>250 (the PCA is either not sending or it is out of range of any receiver).

[0045] Consequently using the simple algorithm above, the position of the PCA may be estimated to be within 50m of a particular receiver.

[0046] Further, if the maximum RSSI is known corresponding to the RSSI when the PCA is closest to a receiver 12, and the minimum RSSI is known corresponding the approximate mid position between two adjacent receivers, then the position of the PCA relative to the receiver with the strongest RSSI may be more closely estimated as:

_^ [RSSI( measured ) - RSSI (maximum )]

[RSSI (maximum) - RSSI (Minimum)] 10047] Unless the direction of movement is known, there may be ambiguity as to which side of a receiver the PCA is located. This ambiguity may be resolved if any direction information contained in the signal is considered, or the trend of RSSI is known as increasing or decreasing relative to successive measurements. As will be further described, the master receiver 10 may include a display so that an operator can observe the trend of RSSI and thereby be able to estimate whether the climber 5 is ascending or descending.

[0048] As an alternative method for extrinsic measurement or estimation of climber position in the shaft, it is feasible to use a movement sensor, for example a counter to count pulses generated by, for example, a wheel in contact with the belt 7 as is well known. This method would give corresponding linear measurement of movement of the belt 7, thereby providing a means of indicating position of a climber within the shaft. However this method is not preferred because of additional cost and operational and component complexity, nevertheless an input for such a sensor to the controller 4 or master receiver 10 could be readily provided.

[0049] Figure 4 illustrates in schematic form one circuit realisation for the receiver 12 of the invention. In the illustrated example, the receiver includes a matching network 66, a directional antenna arrangement 20a coupled to a combiner 67, for example a known Wilkinson combiner or alternatively a non-directional antenna 20 in which case the combiner 67 is not required. The antenna 20 or 20a is used to collect signals from the PCA 9 for detection by a wireless transceiver 52. As noted above, a dual antenna is not required at either end of the shaft, for example for the receivers 12A and 12C of Figure 2.

[0050] Transceiver 52 can be of a commercially available type such as an integrated device made by Texas Instruments, Chipcon CC1 101. As a receiver, the transceiver 52 may be configured as a receiver only. Obviously a receiver rather than a transceiver may be specified. Output from the transceiver 52 is coupled to a processor 24 which also can be a commercially available microprocessor such as an ATmega328 manufactured by Atmel. The processor 24 acquires and processes signals and RSSI information from the transceiver 52 and generates a further signal 42 (Figure 6) which includes RSSI. The processor 24 formats the further signal and outputs it to a communication interface circuit 25 which is coupled to the cable 16. The further signal preferably utilises an RS485 protocol and the communications interface circuit 25 can again be a commercially available device such as a MAX481 manufactured by Maxim Integrated. In the illustrated arrangement, the cable 16 is in a form of a well known multi-drop twisted pair.

[0051] Other protocols such as RS422 or RS232 or custom defined protocols could equally be implemented with an appropriate choice of communications interface. For the RS485 protocol, normally there is a limit of 32 to the number of such interface devices that may be connected to a multidrop line, however this corresponds to a shaft in excess of 3,000m deep, so such a limit is not considered to be a practical disadvantage. The RS485 protocol is preferred however to enhance reliability, speed and immunity to interference.

[0052] Alternatively, the processor 24 may be in the form of digital logic and gate array systems, however it is convenient to use a processor and associated software for the intended purpose. Connections between the microprocessor 24 and the transceiver 52 and interface circuit 25 and other attached peripheral devices are via various ports labelled PI to P10, according to the operating program residing within the microprocessor program memory, as is well known to persons skilled in the art.

[0053] Figure 4 also shows an additional cable 16a to distribute supply voltage to all the receivers 12. The supply voltage on cable 16a may for example be at 48V dc. The receiver 12 includes a converter 58 coupled to the cable 16a to convert output to, for example, 5 volts or 3.3 volts dc for powering various components within the receiver 12. The converter 58 may be, for example, an LM5008A Buck Switching Regulator manufactured by Texas Instruments. The supply voltage on cable 16a at the proximal end should be chosen to be high enough to supply adequate voltage to the distal receiver after allowance for the cable resistance, operating current requirements and minimum voltage for the distal receiver powered from cable 16a.

[0054] In the illustrated arrangement, each receiver 12 also includes an address to uniquely identify it to the master receiver 10. The addresses may be established by a number of methods, for example but not necessarily such pre-wired as a unique fixed firmware address specification in each the receiver 12, set by an on-board address switch 68 coupled to the microprocessor 24 or links appropriately selected and interfaced to the processor, or established using assignment by master receiver 10 such as disclosed in US 6,240,478. The address switch 68 may be a rotary type with 8 or 16 positions with preferred decoding as octal or hexadecimal input/outputs coupled to the microprocessor 24.

[0055] Each receiver 12 may include a display 57, such as a standard OLED display with a 128 x 64 dot matrix display area and integrated driver system interfaced to the processor 24. The display 57 may be arranged to display various parameters including diagnostics, address as set to each the receiver, RSSI, position estimates of the PCA 9 within the shaft 18, error codes or any other relevant information.

[0056] The receiver 12 may optionally include a switch 51 which is preferably in the form of a press button which may be operated by a climber 5. The switch 51 is coupled to the microprocessor 24 so that the state of the switch can be transmitted to the master receiver 10 in order to provide an alert that a climber is ready to undertake a climb using the system. Of course more than one switch may be included to provide other functions as may be useful.

[0057] Figure 5 discloses a block diagram of one possible arrangement for the master receiver 10 according to the invention. In the illustrated arrangement, many of the components of the master receiver 10 are similar to those of the receivers 12 and the same or corresponding components have been given the same reference numeral followed by the subscript (a). Such component similarity confers a manufacturing efficiency, but is not essential to the functionality of the system.

[0058] Generally, in the master receiver 10 the processor 24a operates as a master to manage and coordinate the response to signals received by each the receiver 12 in the system, and in a preferred embodiment, polls each receiver 12 sequentially to acquire the signal originating from the PCA 9 and determine if a valid PCA signal is present in the receiver. Other known methods for communicating to the multiple receivers of the system include time division multiplexing, or other methods familiar to those skilled in the art.

[0059] The master receiver 10 includes a communications interface 25a which in this embodiment is operable to receive and send signals from and to the cable 16 for input to and output from the microprocessor 24a. Again, the interface circuit 25a utilises the same communication protocols as the receivers and therefore it is preferred that an RS485 protocol is utilised. Output from the microprocessor 24a is coupled to a control cable 17 via a transceiver 52a and matching network 66a. In the illustrated arrangement, the control cable 17 is in the form of a coaxial RF cable, and as the transceiver 52a is not necessarily intended as a wireless receiver, it may be configured as a transmitter only.

[0060] As disclosed above, power to the receivers 12 may be supplied on cable 16a or supplied by a battery within respective receivers 12, or optionally supplied from another power source local to the receivers. Where power is supplied from master receiver 10, a further power supply element 58a is included, for example type NPS28-M universal input power supply available from Digikey, to provide the preferred 48V on line 16a, and a standard regulator included to provide local power for example 5V or 3.3V for various circuit elements in the master receiver 10.

[0061] As shown in Figures 4 and 5, the structures of the master and the receivers 10 and 12 are preferably similar thereby minimizing manufacturing costs. The transceiver 52, 52a may be configured to operate both as a receiver for signals generated by the PCA 9 and as a transmitter to send signals to the controller 4. However, in Figures 4 and 5 the transceiver 52a is configured only as a transmitter and transceiver 52 is configured only as a receiver. In addition, a switch 51a is included to perform the same function as disclosed for receivers 12, or other functions as may be desired.

[0062] Master receiver 10 includes a display 57a which may be in the form of an OLED display. The display 57a can display similar information to that displayed on the display 57 of the remote receivers 12. It is preferred, however, that the display 57a operates to include a display to show the approximate position of the PCA and hence the climber 5 in the system. The microprocessor is therefore programmed to produce a display which graphically shows the position of the climber 5. Figure 4a shows one such graphical display 70. The display 70 may be in the form of a bar graph with each receiver 12 depicted as a numeral 1 , 2, 3 spaced alongside a marker 71 representative of a receiver 12 and corresponding to each receiver 12 address. Another marker 74 may be dynamically positioned according to the PCA position determined by an algorithm as disclosed and according to the estimated climber position relative to the inter-receiver positions. Further, the display 70 may include a display field 72 for displaying the estimated distance of the climber from the proximal end of the shaft, and a display field 73 for displaying the receiver 12 corresponding to the best RSSI value, and a display field 73a to display the current RSSI value.

[0063] Obviously, other display depictions may also be implemented. Also it is more useful to have the dynamic display 70 at the master receiver 10, but less useful to have it at each receiver 12. Each receiver 12 could however be arranged to display its set address value to aid in the unambiguous setting of the receiver address to prevent conflict as each receiver is polled.

[0064] Figure 6 diagrammatical ly illustrates one possible signal structure for signals 41 utilized within the system and communication between the PCA 9, master receiver 10, and the remote receivers 12.

[0065] It will be appreciated by those skilled in the art that the microprocessors 24 and 24a can generate signals in various formats for transmission along the cable 16. Figure 6 schematically illustrates one arrangement for possible signal structures for use in the system of the invention.

[0066] Figure 6 shows an example of a PCA signal 41a which could, for example, be the same as that generated by corresponding components in US 8,141,681. The signal 41a includes a preamble and sync field 15, data fields 26 and 28, and error control field 29.

[0067] In Figure 6, a polling address 30 represents a message generated by the processor 24a of the master receiver 10 which is inputted to the cable 16. The message 30 may include other information such as a header, control information and CRC (error control field). Provided, however, the communication system is low noise and interference is minimal, the occasional missed message at any of the receivers 12 is of low consequence to the overall operation of the system and a simple polling message structure as further disclosed herein is found to be adequate in practice. For the description to follow, address 30 is structured as a single 8 bit byte with the following allocation of bit functions :

Bit 7 is the message type; =1 for a data response: =0 for an acknowledge response;

Bit 6 is the RxEnable parameter as further detailed below;

Bit 5 is the Sw parameter as further detailed below, and;

Bits 4, 3, 2, 1 , 0 represent the address parameter Addr having a range 1 to 31.

[0068] Figure 6 shows the typical structure for a response data message 42 which is generated by the microprocessor 24 of a receiver 12 which has been polled. The data message 42 includes a header field 31, identifier field 32, data field 33, RSSI field 34 and error control field 35.

[0069] In the illustrated system, each PCA 9 is provided with a unique serial number which is transmitted by it in the field 26 and this step is useful to prevent other PCA's from interfering with system operation where more than one maybe operating. The message in the data field 28 includes information relating to the control information from the active PCA 9 such as the applied load or desired load, which may be used to manage torque provided by the motor 3. It may further include information such as a selected climb direction, either up or down, or a start or stop signal to initiate or terminate operation of the motor 3.

[0070] Once an addressed /receiver 12 has been polled, its microprocessor 24 is programmed to respond with a data message 42 which is inputted to the cable 16.

[0071] In Figure 6, it is preferred that the data within the fields 32 and 33 mirrors that in fields 26 and 28 respectively of the signal 41a from the active PCA 9. Generally the preamble and sync 15 sections of signal 41a are automatically generated by the transceiver type used.

[0072] The error control signals within fields 29 and 35 can take a different form as is known in the art, however in this disclosure the cyclic redundancy check (CRC) type is preferred. The header field 31 can provide message control information such as the number of elements in the message, message type (data, control or acknowledge) and the source address to confirm to the master receiver 10 that the message 42 originates from the expected receiver 12. In this disclosure, the header 31 is the same structure as address 30.

[0073] Where cable 16 is provided as a half-duplex system, then the master receiver 10 maintains control of the direction of transmission on the cable 16, such a process being well known. Specifically, each of the receivers remain in the listen state until addressed; responding by placing information 42 on line 16 within a specified time, for example 5 millisecond, thereafter resuming the listen state.

[0074] Message structure can be dependent on the data message 42 formed from the active PCA 9, such data most likely being asynchronous to polling of the receivers and may be considered as occurring in the background. Preferably the data is double buffered in the receiver 12 as is well known to minimize information loss. Obviously other structures could equally be implemented, however the disclosed structure is adequate for purpose.

[0075] Additionally, where a polled receiver 12 responds with message 42, then if there is no data for the response, then an acknowledgment message structures as 30 may be sent by the polled receiver so the master receiver 10 does not consider the polled receiver absent from the network.

[0076] Other signal structures in other formats may also be used. For example but not necessarily, for a climb assist system wherein a crane-control type of controller is the primary short-distance control method, then the message structure may differ from that of Figure 6. Where a crane control type of application is operative, then the various components could be altered accordingly, including the master receiver 10 communicating to the alternative controller 4 via link 17, the message structures 41 and the functioning of the wireless ^* transceivers 52, 52a. Typically, a crane-control device would allow manual control of direction of climb, speed of climb, level of support, start and stop, or any combination of these capabilities or any additional capabilities of the crane-control device, and may not necessarily include the serial number portion of the message.

(0077] Figure 7 shows a flow chart 36 for one possible algorithm for operation of the master receiver 10 according to the invention. Program instructions for carrying out the algorithm are stored in the microprocessor 24a or in a separate memory (not shown) to which the microprocessor 24a has access. Following a power-on step 147, initialisation of any input/output ports, timers, and other peripheral devices as are found in the microprocessor, and other connected devices such as the display 57a and transceiver 52a, and initialisation of the memory of the microprocessor 24a is performed.

[0078J Following an initialisation step 37, the master receiver 10 acts to identify the addresses of all the receivers 12 which are connected on the system. Whilst the practical realisation of the invention of this disclosure includes a variety of system and signal error management functions, details of these are not necessary for an understanding of the novel aspects of the invention, and so are not included.

[0079] At step 38 the List representing a sequential list of address of connected receivers is cleared, and at step 39 the list pointer is set to 1 being the pointer to the location in memory of the address, parameter Addr of the first receiver 12, and a corresponding initial address = 1 is set.

[0080] The loop continued at step 40 from question 148 operates to identify all receivers 12 in the system and form the array List of such connected receivers as follows: At step 40 interface 25a is set to send mode and at step 43 the address message 30 is constructed and then placed on the cable 16 to all receivers 12, and the interface 25a is set to listen mode at step 44. At step 45 timeout TimerB is set, for example to 5ms.

[0081] Provided a response is received as at question step 46 from the addressed receiver 12, then at question step 47 provided the timeout period of step 45 has not completed, the address corresponding to the responding receiver is stored at step 48 sequentially in the List memory location, thereby registering each receiver connected in the system. If a response is not detected in the timeout period, the address is not stored in the List. Thereafter the List pointer is incremented in step 49 to the next sequential storage location, and the address is incremented in step 50. At question step 148 if the number Amax, for example 31 , of all possible addresses have not been polled, the loop repeats at step 40.

[0082] It is obvious that the position algorithm as described above relies on the incremental address being monotonic and corresponding to sequential positioning of receivers in the shaft such that the estimate of position is realistic. However operation of the system does not depend on such allocation of addresses, only that each receiver is assigned a unique address. Otherwise collision of messages from two or more receivers will occur causing the system to be potentially non-operative.

[0083] Methods such as randomized jitter in the response times of each receiver or other known methods of address allocation may be used to overcome this, but in the practical implementation of the system, it is regarded as adequate to expect that each receiver is allocated a unique address.

{0084] Preferably all the receivers 12 are addressed sequentially from the receiver with address 1 corresponding to the receiver 12 nearest to the master receiver 10. After formation of the address List, then at step 149 the parameter Sw to register if any button 51 or 51a has been pressed, and parameter RxEnable are cleared. These parameters are used hereafter to control functions in the receivers 12. At step 53 the record DataFile which is a file that progressively stores responses from each receiver 12 where such response is that of a PC A signal, is cleared. At 61 the List pointer is set to the initial value of 1 corresponding to the address of the first receiver 12.

(0085] As is apparent from Figure 7, a loop, defined from step 149 through to step 124 corresponds to a complete polling of all connected receivers 12 and processing of any valid signals, and a sub-loop commencing at question step 62 through to step 1 19 provides polling and response storage in memory for a single specified receiver 12.

[0086] When all addresses in the record list have been polled at question step 62, the algorithm continues at question step 125 where a check is made to see if any buttons 51 on any receiver 12 or button 51a on master receiver 10 have been pressed. If so, evidence of such is available to the master receiver either directly via button 51a, or as bit 5 of response message 42 in the first byte 31 , being set.

[0087] Message 42 may have two structures: if data from a PCA is being returned, the components 31, 32, 33, 34 and 35 are present and bit 7 of header 31 is set to 1. If the message 42 is not representative of data and is an Acknowledge message, then only the header 31 need be returned, with bit 7 = 0. In both cases bit 5 of 31 is either cleared or set representative of no button 51 having been pressed, or retaining memory of a button 51 having been previously pressed.

[0088] As the pressing of a button 51, 51a represents signalling the intent of a climb to start, and if parameter RxEnable is not set in step 126, it is set in step 127 and timeout period TimeA, for example 10 seconds, is started at step 128a provided TimerA is not already running as at question step 128, then continues at step 129. TimerA period is intended to give the climber time to operate the PCA and start a climb. The function of parameter RxEnable is to enable all receivers 12 to receive PCA messages or send data to the master receiver 10. If parameter RxEnable is set at question step 126, then a climb is underway and the system continues the polling sequence at step 120.

|0089] If the timeout period TimeoutA at step 128 has not completed as at question step 129, then at question step 120 the record DataFile is checked for any PCA responses, and if none are found, then at step 124 a delay of preferably 125ms is initiated. Thereafter a new poll sequence is initiated at step 53. Delay 124 is intended to limit the rate of polling to give the data rate expected by controller 4, and clearly may be adjusted to suit other expectations Obviously the poll rate set by delay 124 need not be faster than the availability of data from the PCA, which determines the useful poll rate.

[0090] At step 120 if the record DataFile contains any entries, then the entry with the highest RSSI is selected 121 and checked for usefulness at question step 122. If RSS1 is less than a specified value, for example less than -lOOdBm, the delay 124 is initiated, otherwise a message 42 containing the PCA data is formed at step 123 in the form expected by controller 4 and sent on cable 17. Thereafter the delay at step 124 is initiated. Following receipt of the message 42 by the controller 4, the climb assist system 1 operates as though it was in direct communication with the PCA 9 without regard to the distance between the PCA 9 and controller 4.

[0091] At question step 62 if there are further addresses to poll in the array List, then the next address parameter Addr is accessed in step 63 and the poll routine 65 entered at step 64 as further described in Figure 8. At step 130 a poll message 30 is formed with the parameters RxEnable, Sw and the Addr value included, with data type being bit 7 being set to 1. A typical poll message may be in 8 bit binary form: lxOaaaaa where x=l or 0 accordingly as RxEnable is set or cleared, parameter Sw is irrelevant and may be set to 0, and 'aaaaa' represents the 5 bit address parameter Addr of a specified receiver 12 in the range 1 to 31.

[0092] At step 131 interface 25a is set to send, the poll message is placed on line 16 to all receivers 12 at step 132 and the interface 25a is set to listen at step 133 for a response from the addressed receiver 12. Then at step 134 a timeout TimerB is initiated, for example 5 ms within which time a response is expected from the addressed receiver 12.

[0093] If no response is received within the timeout period at question step 136, the program continues at question step 145. As a response is expected as the connection with the specified receiver 12 was earlier established, an error message may be generated (not shown) and sent to a monitoring function (also not shown).

[0094] If a response is forthcoming at question step 135, then if software switch 137 is set to position B, and at question step 141 if a data message is returned with bit 7 of the header 31 equal to 1, then at step 142 the message 42, with data in the fields 31, 32, 32 and 34, is stored in the data file, and at step 143 a timeout TimerC is started or restarted, for example 30 seconds.

[0095] The purpose of TimerC is to cause a reset of the system after this period if no further messages are received from a PCA as shown at question step 145 when the timeout time at step 143 completes, and if the association function is implemented, association is cleared at step 146 and the program resumes at step 149 of Figure 7. As TimerC is restarted at step 143 each time a message is stored to the DataFile, path Y to step 1 19 is then followed and the program resumes at step 1 19 of Figure 7, wherein the List pointer is incremented and question step 62 follows as previously described.

[0096] If an acknowledge response is detected at question step 141 with bit 7 =0 of parameter Addr signifying that a data response was not received, then at step 144 the event of a switch 51 or 51a being operated is included as a logical OR function to set parameter Sw, and hence bit 5 of header 30. This bit 5 of header 30 is not reset until TimeoutA at step 128 completes which will occur only if a climb is not initiated within for example 10 seconds of pressing button 51 or 51a as represented by the equation of step 144: [Sw = Sw + 51 + 51a], where 51 and 51a mean the state of switches 51 and 51a of Figures 4 and 5 respectively, and the symbol "+" is the logical OR operator.

{0097] The algorithm may include optional steps 138, 139 and 140 and software selection shown diagrammatically as switch 137 in Figure 8. It will be seen that the switch 137 is coupled to question step 138 and via point A to determines if there is an association already set. If association is set, at question step 140 the PCA as specified by its serial number (SN) is checked against the PCA already associated with an active climb: if the SN's match then the algorithm continues at question step 141 , the PCA signals being accepted. If the association is not set, then the first occurrence of the PCA being received by any receiver, an associate flag is set as indicated by step 139. For subsequent PCA signals, only if it is the same PCA as evidenced by the same PCA serial number being detected, will the data be stored through step 141 , as determined by question step 140.

[0098] Signals from any other PCA will not be stored once a specified PCA is associated at its first transmission. The associate flag in step 139 becomes unset if no transmissions are received from an associated PCA for a period, for example 30 seconds at step 146, signifying that a climb has concluded. It is also preferable to omit steps 138, 139, 140 where similar functions are provided in the controller 4 or where such associate facilities are not required, in which case a yes output from question step 135 is linked directly to question step 141.

[0099] As further understanding of the selection of either switch 137 being position A or B, if the PCA 9 provides a unique identification in its transmitted signal and if the controller 4 is association capable, then switch 137 may be set to position A. Otherwise if either of PCA 9 or controller 4 is not association capable, then only setting switch 137 to position B is relevant.

[0100] For those skilled in the art, it is evident that there are alternatives for messaging and providing control information. However it is preferred from commercial considerations that no modifications to either hardware or software of the PCA or climb assist controller are made where it is a commercially available product, although it may be feasible to incorporate the master function within the controller if desired.

[0101] Alternatives to digital communications as above for communications between receivers may include well known mesh or networked radio systems such as Zigbee based on the IEEE 802.15 standard, however this and other similar methods are not considered further as they will require power distribution for operation thereby requiring cabling in the shaft, and being radio systems, have additional signal loss considerations for signal transmission, and do not confer any advantage to the system of the invention.

[0102] Figure 9 discloses a flow chart 60 for one possible algorithm for operation of the receiver 12 according to the invention. Program instructions for carrying out the algorithm are stored in the microprocessor 24 or in a separate memory, (not shown) to which the microprocessor 24 has access.

10103] Following a power-on step 101, initialisation of any input/output ports, timers, and other peripheral devices as are found in the microprocessor, and other connected devices such as the display 57 and transceiver 25, and initialisation of the memory of the microprocessor 24 is performed at step 102.

[0104] At step 103 parameters Sw and RxEnable are cleared. When set, the parameter RxEnable enables receiver 12 to receive PCA message transmissions. An address unique for each receiver 12 as set by address switch 68 is then stored as indicated by step 104. Once the parameter Sw is set, it may remain set until either the receiver is reset or no PCA signal has been received by any receiver in the local network for a predetermined period, for example 10 seconds where a climb is not begun, or 30 seconds where a climb has ended.

[0105] The flowchart 60 includes a listen mode step 105 during which the interface circuit 25 is set to listen mode and at step 106 the receiver checks for the poll address 30 and its equality with the receiver address, otherwise a loop formed by steps 105 and 106 continues cycling while the receiver 12 waits for an address match.

[0106] When the poll message 30 is received and is same as that of receiver address and the address field 30 in the poll message, at question step 107 the receiver checks if it is enabled to receive a message from a PCA 9. If parameter RxEnable is not set, parameter Sw is cleared at step 108, an optional indicator LED is set to green at 109 signifying the readiness of the system to receive first data from a PCA, and the event of a button 51, if having been pressed is recorded to parameter Sw at step 1 10. Preferably the event of a button being pressed is sensed by way of an interrupt and such an event may then be recorded as happening asynchronously with the receiver algorithm. The algorithm then continues at step 1 16.

[0107] Similarly, the event of any timer reaching its prescribed time value and timing out may be recorded as happening asynchronously with the receiver or master receiver algorithm and may be effected as an interrupt as is well known.

[0108] At question step 107, if parameter RxEnable is set, then step 1 1 1 follows where the transceiver 52 may be checked for receipt of data from a PCA. If no PCA data is present then at question step 112 if the optional indicator LED is not set to red, then the LED is set to flash red and green alternately at 1 13 signifying that the climber has the duration of TimerA at ste 128, for example 10 seconds, to begin a climb by operating a PCA. If the LED is already set to red then at step 1 14 the red state for the LED is retained and at step 1 15 a data message is formed.

[0109] At steps 1 15 and 1 16 a message 42 with header 31 is formed, for example: Oxyaaaaa (in 8 bit binary form) for an acknowledge message (step 1 16), or Ixyaaaaa plus data in the fields 32, 33, 34, 35 for a data message (step 1 15). As before the header 31 is structured as:

Bit 7 is the message type: =0 for an acknowledge response or =1 for a data message; Bit 6 is the RxEnable parameter and is not affected by any receiver 12;

Bit 5 is the Sw parameter, and is set according to a button 51 being pressed;

Bits 4, 3, 2, 1, 0 (aaaaa) represent the parameter Addr having a range 1 to 31.

[0110] At step 1 17 the interface 25 is set to send mode and the message is placed on the cable 16. Because the address in header 31 as represented by structure 30 of message 42 is always present in any message as the address of the polled receiver 12, other receivers in the system ignore the message and remain unresponsive. At step 1 18 the message is placed on line 16 and the algorithm continues at step 105.

[0111] It is noted that such store-and-forward systems are well known to those skilled in the art, and may be implemented in a variety of methods and are to be regarded as equivalently disclosed. [0112] The switch 51 of Figure 4 and 51a of Figure 5 may comprise a press button associated with the receivers and master, and may be optionally included to alert the system that the climber 5 is ready to undertake a climb using the system. The purpose for inclusion of the switch is to limit operation of a climb assist system to the event of a specific PCA being operative to a specific climb assist system as described above. However where it is not of concern for the system to be responsive to multiple PCAs, the specific provisions related to sensing the button 51, 51a may be omitted. However it is preferable to implement the press button operation in all the receivers where interfering PCA operation may be. received, such as receivers that may be within for example 50m of other comparable systems. Also it is preferable that where the button function as detailed in this disclosure is provided, then there is an additional button capability placed at the base of the shaft being the start point of an upward climb which, for convenience, may be provided by a receiver with the highest address.

[0113] A further facility enabled by the press button 51, 51a is where multiple systems such as that shown diagrammatically in Figure 10 such as in a shaft where it is desired to position independent climb assist systems one above the other to allow for multiple climbers within the shaft. In Figure 10 the same reference numerals followed by the letter 'c' have been used for equivalent components. An alternative arrangement of multiple independent climb assist systems is for example where several systems are operated in parallel positions, such as for ladders spaced around a chimney stack or in other arrangements of relative proximity.

[0114] In such an arrangement as Figure 10, there is the possibility of a climber at or near the top of the lower section causing initiation of motor activity in the upper system if the radio range from the lowest receiver in the upper system encompasses a portion of the top of the lower system. When, however, the press button functionality is included, preferably on selected the receivers for example at the top and base of a ladder or on the master receiver, operation of the press button preferably selectively initiates a timeout function such that the climber has a limited time, for example 10 seconds, to initiate a climb. Thereafter the system resumes a non-responsive condition unless a climb has been started or until the press button is pressed again. Other systems remain non- responsive unless that other system's press button is pressed and where the association functionality is also included but not active in preventing unwanted PCA responses.

[0115] It is only necessary to include switches on receivers or master receivers where the radio range to a second system is such that operation of a PCA on a first system could cause second system to operate.

[0116] To limit the possibility of another operating PCA causing operation of the system, it is preferable that such other operating PCAs are out of the radio range of the position where operation is being initiated. Where a single system is operational, then the function of the press button may be removed and the system software adjusted accordingly, being responsive to PCA signals whenever emitted.

[0117] Further, as radio range is determined by the signal strength emitted by the PCA and reception sensitivity of the receivers, it is also feasible to reduce either or both PCA emitted signal strength or receiver sensitivity and consequently reduce spacing between each receiver and master receiver accordingly, thereby reducing the potential for interference by an PCA with an unrelated system.

[0118] Alternatively, each independent system may be configured such that it is responsive only to a specific PCA, for example by incorporation of a selected serial number as 26 of Figure 6, the function of the press button then being optional, all other systems then remaining unresponsive.

[0119] As a further note, where the button function is included and encompasses all receivers in the system, then if a climber's PCA stops sending for more than for example 30 seconds, the climber will need to climb unassisted to a nearest receiver to press a button, In this case the system may be adapted such that for all intermediate receivers^ that is excluding the first and last addressed receivers, the parameter RxEnable is permanently set, and the indicator LED may then show green signifying it is ready to accept PCA signals.

[0120] Where multiple PCA signals are being received at the receiver, intermittent signal errors may occur from the uncorrelated multiple PCA signals. Filtering of signal errors may be performed in the microprocessor associated with the receiver, however such filtering and processing of signals in error is preferably but not necessarily managed by the controller 4.

[0121] One advantage of the invention as disclosed herein allows effective radio range to be extended over essentially unlimited distances and allow for non-linear shaft geometries where line-of-sight is intermittent throughout the range, and to provide indication of the approximate position of the climber throughout the span and duration of a climb, allowing monitoring of climber progress.

[0122] A further advantage of this invention is to selectively enable a climb assist system for use, thereby allowing operation of multiple systems where there is some measure of proximity of the sender apparatus to more than one system.

[0123] As each climb assist system such as referenced in this disclosure are restricted to use by a single person to avoid interference of the level of support provided to each climber, the utility offered by multiple systems stacked vertically is that as many climbers can be climbing as there are systems, one significant advantage then being the corresponding higher utilisation of the overall system, for example in facilitation of rapid escape in deep mines.

[0124] It is understood that where it is implied that specific types of electronic circuitry are disclosed, that alternative embodiments can include general purpose processing units configurable by software and/or firmware, and hardware methods including but not exclusively programmable logic devices, discrete logic devices, or a combination of any of the aforementioned methods.

[0125] It is also understood that where specific hardware is proposed such as a press button, this equivalently includes any other means of signalling intent such as alternative sensor methods of non-contact sensing such as capacitive, proximity, optical or other methods as are well known.

[0126] It is also understood by those skilled in the art that other algorithmic implementations may be proposed, However the embodiment herein is intended to be instructive and not restrictive.

[0127] As the circuit design uses conventional and well known methods understood by those skilled in electronic design, the various additional components required to effect the full circuit diagram and description are understood and do not need to be shown in detail.

[0128] While the present disclosure has been described in connection with the preferred embodiments of the various Figures, it is to be understood that other similar embodiments may be used or modifications and additions may be made to the described embodiment, essentially performing the same function of the present disclosure without deviating therefrom. Furthermore, it should be emphasized that a variety of applications, including rock climbing, building maintenance or rescue or escape methods, or any other application requiring substantially vertical transport of a person are herein contemplated.

|0129] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

LIST OF PARTS

[0130]

lifting system 1 ladder 2 motor 3 controller 4 person 5 rope grab 6 belt 7 sheave 8

PCA 9 master receiver 10 antenna 1 1 receiver 12 communication system 14 preamble 15 cable 16 cable 17 shaft 18 antenna 20 microprocessor 24 interface 25 pea sn 26 data 28 error control field 29 address byte 30 header 31 pea sn 32 data 33 rssi 34 error control field 35 flow chart 36 step 37 step 38 step 39 step 40

PCA signal 41a message 42 step 43 step 44 step 45 question step 46 question step 47 step 48 step 49 step 50 button 51 transceiver 52 step 53 display 57 converter 58 flowchart 60 step 61 question step 62 step 63 step 64 poll routine 65 matching network 66 combiner 67 graphical display 70 bar graph 71 display field 72 display field 73 marker 74 power on step 101 step 102 step 103 step 104 step 105 question step 106 question step 107 step 108 step 109 step 110 question step 1 1 1 question step 112 step 1 13 step 1 14 step 115 step 1 16 step 1 17 step 1 18 list +1 step 1 19 question step 120 step 121 question step 122 step 123 step 124 question step 125 question step 126 step 127 step 128 question step 129 step 130 step 131 step . 132 step 133 step 134 question step 135 question step 136 software switch 137 question step 138 step 139 question step 140 question step 141

Step 142 step 143 step 144 question step 145 step 146 power on step 147 question step 148 clear step 149