GB2504126A

GB2504126A - Discontinuous optical communication between a transmitter located off-axis on a rotor and a receiver located on a stator

Info

Publication number: GB2504126A
Application number: GB201212901A
Authority: GB
Inventors: Doina Daciana Iliescu; Peng Huang; Mark Leeson
Original assignee: University of Warwick
Current assignee: University of Warwick
Priority date: 2012-07-20
Filing date: 2012-07-20
Publication date: 2014-01-22
Also published as: GB201212901D0

Abstract

This application concerns optical communication between a first machine part 2 and a second machine part. The first machine part rotates about an axis and can be regarded as a rotor, while the second machine parts acts as a stator. An optical transmitter 6 is located off-axis on the first machine part 2, and an optical receiver 7 is located on the second machine part 3 such that there is no continuous line of sight between the transmitter and the receiver. The transmitter 6 is adapted to communicate the data to the receiver 7 optically in one or more communication sessions in periodically occurring time windows when there is line of sight. Preferably the transmitter and receiver may each form part of respective transceivers, so that bidirectional communication may take place. The receiver may be adapted to determine the reliability of transmitted signals and to use this information to determine when to start or terminate communication sessions. Prior to establishing a data session, the receiver may transmit a search signal to the transmitter containing synchronisation codes. Confirmation frames (aka acknowledgment messages) may be exchanged.

Description

Apparatus for communicating data Des cription The invention relates to apparatus suitable for communicating data from a first machine part to a second machine part wherein, in operation, the first machine part moves repeatedly in relation to the second machine part.

The health condition of a component of rotating machinery, such as a power generator rotor, maybe monitored in three ways: (i) off-line, using a number of techniques; (ii) on-line, i.e. during operation, using indirect methods involving voltage and current measurements of the stator coils; and (iii) on-line, using direct methods of data collection from sensors placed on the rotor.

Off-line methods cannot provide real-time data and can re'y on the rotor being placed in a laboratory setting or in overhaul.

For indirect methods, the data does not indicate the rotor condition in a direct manner and so considerable data processing and modelling can be needed to detect faults before damage occurs.

For direct methods, transferring the data from the rotating to the non-rotating components can be difficult. Approaches include direct contact, such as through slip rings, and wireless communications, such as radio frequency or optica' wireless communications. Since direct contact can Emit the rotor performance, wirdess communications can be preferable. Optical wireless communications can be preferable to radio frequency communications since the latter is subject to electromagnetic interference due to strong dectromagnetic fidds in the machinery.

Ganchev eta!., "Rotor temperature monitoring system", 19th International Conference Ofl Electrical Machines (ICEM), 6-8 September 2010, page 1, describes a rotor temperature monitoring system in which the data transmission between the rotating and stationaly part is realized via infrared light and in which the transmifler is mounted on the shaft stub.

Wassermarn et a!., "Wireless Data Transfer' System for' Rotating Machinery -Very Robust Against Electromagnetic Interference", 1s1 International Conference on Sensing Technoo, 21-23 November 2005, page 647, describes a system in which optical data transfer is carried out by a "ring-shaped" infrared transmitter array clamped around the shaft body and a corresponding infrared receiver array.

The invention seeks to provide an improved system.

According to a first aspect of the invention, there is provided apparatus for communicating data from a first machine part to a second machine part wherein, in operation, the first machine part moves repeatedly (e.g. periodically or aperiodically) in relation to the second machine part, the apparatus comprising an optical (e.g. infrared) transmitter arrangeable on the first machine part, and an optical receiver arrangeable on the second machine part such that, in operation, there is only a line of sight between the transmitter and the receiver during a plurality of separate time periods, wherein i the transmitter is adapted to communicate the data to the receiver in one or more communication sessions in respective ones of the time periods.

Thus, there is no need for the transmitter and receiver to be mounted in specific locations thereby providing a continuous line-of-sight data link. Hence there can be more flexibility when mounting the transmitter and receiver. Moreover, there is no need for additional components, e.g. additional transmitters or receivers, or complex mounting or contacting parts.

In operation, the first machine part may rotate about an axis of rotation. The line of sight may lie on a different Une from the axis of rotation.

In operation, the speed of the movement may be more than 1000 cycles per minute.

The ength of the time period may be less than 100 microseconds.

The transmitter may be adapted to obtain the data from one or more sensors that are also arrangeable on the first machine part.

The data may be communicated via a fast fading channel.

The data may be communicated in a signal comprising a plurality of symb&s.

The receiver may be adapted to only process symbols that have a higher power than a predetermined threshold.

The receiver may be adapted to determine the reliability of each symbol and to begin, continue or end the communication session accordingly. The signal may comprise constant-length pulses and the receiver may be adapted to determine the reliability of the symbol by comparing the time between two successive rising edges with the time between two successive falling edges.

The apparatus may comprise a first transceiver comprising the transmitter and a further optical receiver, and a second transceiver comprising the receiver and a further optical transmitter, wherein the further transmitter and the further receiver are adapted to communicate with each other in the same way as the transmitter and the i receiver.

The second transceiver may be adapted to transmit a search signal and the first transceiver may be adapted, in response to receiving the search signal, to begin transmitting the data. The first transmitter may be adapted to transmit the data in a sequence of frames and the second transceiver may be adapted, in response to receiving one of the frames, to transmit a confirmation frame.

The transmitter may be adapted to transmit the data continuously.

The receiver may be adapted to determine the extents of the communication sessions.

The apparatus may further comprise at least one additional optical transmitter arrangeable on the first machine part or on an additional machine part that, in operation, moves repeatedly in relation to the second machine part, the additional o transmitter adapted to communicate with the receiver in the same way as the transmitter.

The transmission medium may comprise air, another gas, a liquid, or a transparent or semitransparent solid.

There maybe provided a machine comprising apparatus according to any preceding claim, wherein the transmitter is arranged on the first machine part and the receiver is arranged on the second machine part such that, in operation, there is ody a line of sight between the transmitter and receiver in the plurafity of separate time periods.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1(a) illustrates an example arrangement of data communication apparatus on a machine. A cross-sectional view is shown.

Figure i(b) illustrates another example arrangement of data communication apparatus on a machine. A perspective view is shown.

Figure 2 illustrates an example data communication apparatus.

Figure 3 illustrates an example of the signal received by a data receiver.

Figure 4 illustrates an example method of determining the reliability of a signal comprising separate constant-length pulses.

Figure 5 illustrates an example method of communication between a data transmitter and a data receiver.

Figure 6(a) illustrates an example search signa' transmitted by a data receiver.

Figure 6(b) illustrates an example data frame transmitted by a data transmitter.

Figure 6(c) illustrates an example confirmation frame transmitted by a data receiver.

Figure 6(d) illustrates example sequence bits used in the frames of Figures 6(b) and 6(c).

Referring to Figures i(a) and i(b), an example machine 1 will now be described.

The machine 1 inchides a first machine part in the form of a rotor 2, and a second machine part in the form of a stator 3 (not shown in Figure i(b)). In operation, the rotor 2 moves in relation to the stator 3 and, in particular, rotates about its axis, as indicated by the Une 4.

In other examples, the machine may include first and second machine parts that are movable in other ways, e.g. linearly in relation to each other.

Data communication apparatus 5 is arranged on the machine 1. The data io communication apparatus includes a data transmitter 6 and a data receiver 7.

The data transmitter 6 is provided on the rotor 2 and the data receiver 7 is provided on the stator 3.

Thus, data from one or more sensors (not shown) arranged on the rotor 2 can be transferred from the data transmitter 6 to the data receiver 7 and, from there, to apparatus (not shown) adapted, for example, to analyse the data.

In other examples, the data transmitter 6 may be provided on the second machine part 3 and the data receiver 7 may be provided on the first (moveable) machine part 2. The first and second machine parts 2,3 maybe parts of different machines.

As will be explained in more detail below, the data transmitter 6 preferably includes both a transmitter and a receiver. Similarly, the data receiver 7 preferably includes both a receiver and a transmitter. The transmitter included at the data receiver 7 and the receiver induded at the data transmitter 6 may be for control signalling.

The data transmitter 6 and the data receiver 7 are adapted to communicate with each other using optical radiation, e.g. ultraviolet, visihle or infrared dectromagnetic radiation, preferably infrared radiation.

The data transmitter 6 and the data receiver 7 are arrangeable on the first and second machine parts 2, 3 respectively such that, when the machine is in operation, e.g. when the rotor 2 is rotating, there is a line of sight 8 between them only periodically. By "line s of sight", it is meant that at least some of the radiation transmitted by the data transmitter 6 can be received by the data receiver 7 (and \qce versa if appflcable).

For examp'e, in Figure ia, the data transmitter 6 is positioned on an outer radiafly facing surface of the rotor 2, and is orientated to transmit in an outwards radia' direction. The data receiver 7 is positioned on the stator 3 at the same axia' position as the data transmitter 6 and is orientated to receive outwardly radially transmitted radiation. Here, the radial and axial directions relate to a cylinder defined by the (rotating) rotor 2.

In other examples, the data transmitter 6 may not be arranged on an outer radially io facing surface of the rotor 2. For example, it maybe positioned on the end surface of the rotor 2. Mternatively or additionally, the data transmitter 6 may not transmit wholly in an outwards radial direction. For example, it may transmit partly or wholly in a tangential direction (in relation to the cylinder defined by the (rotating) rotor 2) or it may transmit partly in the axial direction.

In another example, in Figure ib, the data transmitter 6 is positioned on an end surface of the rotor 2 at a distance from the axis of rotation of the rotor 2, and is orientated to transmit in an axial direction. The data receiver 7 is positioned on the stator (not shown) at the same radial distance from the axis of rotation of the rotor 2 as the data transmitter 6, and is orientated to receive radiation transmitted in the axial direction.

In all cases, the arrangement of the data receiver 7 in relittion to the data transmitter 6 is such that there is only a line of sight between them during a part of each revolution of the rotor 2.

Referring to Figure 2, an example data communication apparatus 5 comprising a data transmitter 6 and a data receiver 7 will now be described.

The data transmitter 6 indudes a controller 20, transmitter circuitry 21, receiver sO circtutry 22, an infrared light-emitting diode 23, and an infrared photodiode 24.

The data transmitter 6 may also indude further components. For examp'e, the data transmitter 6 may inchide an interface (not shown) for receiving data from one or more sensors.

The transmitter circuitry 21 is adapted to convert a digit& signal from the controfler 20 into a signa' for causing the Eght-emitting diode 23 to transmit optica' radiation wfth a suitable (modiflated) power evel.

The receiver circuitry 22 is adapted to convert the signal from the photodiode 24 into a suitable signal to be provided to the controller 20. The receiver circuitry 22 may include a transimpedance amplifier (not shown) operatively connected to the photodiode 24 and automatic gain control (AGC) and threshold circuitry (not shown) operatively connected to the transimpedance amplifier. The controller 20 may he operatively connected to the AGC and threshold circuitry.

The controller 20 is adapted to control how the data is to be communicated from the data transmitter 6 to the data receiver 7.

In some examples, the data is mere'y transmitted in a continuous stream. In this case, only data that is transmitted during a communication session (32; Fig. 3) may be actually received by the data receiver 7.

In other examples, the data is stored and only transmitted during a communication session (32; Fig. 3). In this case, comp'ete sets of data can be reliably communicated to the data receiver 7. Examp'e methods of communicating the data in this way will be described below.

The controfler 20 may comprise a microcontrofler, a field-programmable gate array, or other suitable data processing apparatus.

The data transmitter 6 has a power source which is preferab'y a battery (not shown). In this way, there is no need to provide a connection to an external power source, which may be difficull due to the movement of the data transmitter 6 during operation of the o machine 1. As will be explained in more detail below, the data transmitter 6 is preferab'y adapted to have a tower power consumption than the data receiver 7.

Allernativey or additionafly, the data transmitter 6 may indude components (not shown) for harvesting energy from the environment, e.g. via electromagnetic induction.

Mternatively or additionally, the data transmitter 6 maybe adapted to convert a part of the power in the optical signal from the data receiver 7 into electrical power for powering the data transmitter 6 and/or for recharging the battery. The photodiode 24 may be adapted accordingly and/or additional components (not shown) may be provided to achieve this. Alternatively or additionafly, the data transmitter 6 maybe adapted to change its power state in dependence upon the optical signal from the data receiver 7, for examp'e by switching on in response to receiving the signal and switching off if no signal is received, e.g. for a certain period of time.

The data receiver 7 includes a controller 25, transmitter circuitry 26, receiver circuitry 27, an infrared light-emitting diode 28, and an infrared photodiode 29. Each of these components maybe the same as, or similar to, the corresponding components of the io data transmitter 6.

The data receiver 7 may also include further components (not shown) such as, for example, a further communications interface for communicating with apparatus for analysing the data, a user interface and/or storage.

The data receiver 7 may be connected to an external power source, e.g. mains electricity.

Referring to Figure 3, an example signal 30 received by a data receiver 7 from a data transmitter 6 during operation of the machine i will now be described.

As will be appreciated, any signal received by the data transmitter 6 from the data receiver 7 will have similar properties.

The data transmitter 6 may continuously transmit a (modifiated) optical signal, wherein the modulation may be such that the transmitted signal is either transmitted at a certain power level or is not transmitted. For example, in the case of on-off keying, the presence of the transmitted signal for a certain period of time represents a "1" and an absence represents a "0". The figure illustrates the power envelope of the signal o received by the data receiver 7 when the data transmitter 6 is transmitting such a signal.

The received signal 30 appears in a communication window 31 once per rotation, i.e. with a period of 21t/o) , where w is the angular frequency.

The ratio of the duration of the communication window 31 to the period of rotation is independent of the speed of rotation (when this speed is constant). This ratio svfll be referred to as the "communication window ratio" (CWR). The CWR depends mainly on the configuration of the data communication apparatus 5. For example, it depends mainly upon the radiation pattern of the light-emitting diode 23 at the data transmitter 6, the area of the photodiode 29 at the data receiver 7 and the relative arrangement of the data transmitter 6 and the data receiver 7 (e.g. their separation and relative orientation).

A typical value for the CWR is 1o.

In this case, for a speed of rotation of 3000 rpm, i.e. a period of rotation of 20 ms, the duration of the communication window 31 is 20 In typical applications, the speed of rotation is around 1000 rpm or more and the duration of the communication window 31 is around 100 ps or less.

These values may also vary. For example, the CWR maybe less than io-3, e.g. 104, or more than io-,e.g. lo_2. The (maximum) speed of rotation may also be less than 1000 rpm, e.g. 500, 300 or 100 or rpm, or more than 1000 rpm, e.g. 2000, 5000 or 10,000 rpm. The duration of the communication windows 31 may also be more than 100 ps, e.g. 500 or 1000 us, or less than 100 ps, e.g. 50, 20, 10 or 1 p5.

The Infrared Data Association (IrDA) communication protoc& is unsuitable for transmitting data via such a channd due to the nature of the pairing procedures and the data frame definitions thact it emp'oys.

As can be seen, the power of the received signal 30 fades in and out in each communication window 31. The channel can be characterised as a fast-fading channel.

This may be because the radiation transmitted by the fight-emitting diode 23 at the data transmitter 6 may be diffusive and when the light-emitting diode 23 moves past the photodiode 29 at the data receiver 7, the position of the photodiode 29 changes from the radiation edge to the centre and to the edge again. The fading may also be s because the area of alignment between the diodes 23, 29 changes during the movement, -10-because the distances between the diodes 23, 29 changes, and/or because the blocking of the radiation by, for example, other parts of the machine 1 changes.

The duration of the communication session 32 in each communication window 31 is less than that of the communication window 31 and is determined by a threshold strategy and a required bit error rate (BER).

As mentioned above, the receiver circuitry 27 preferably includes AGC and threshold circuitry. The AGC circuitry is adapted to maintain a stable output during a io communication session 32. The threshold circuitry is configured with a threshold value 33 somewhat lower (e.g. 20 %) than this stable output value. This expands the communication session 32 and, in the margin periods, large signal variations may exist and the signal power may not reach the power 34 required to obtain a specified BER.

Thus, communicating data in the margin periods can be unreliable. However, as will be i explained in more detail below, the boundaries of the communication sessions 32 can be determined from the variations in the pulse widths during the margin periods.

The data communication apparatus 5 is preferably adapted to monitor the condition of the channel in real-time in order to determine the boundaries of the communication sessions 32. This is because the speed of rotation of the rotor 2 and hence the times of the communication sessions 32 will generally vary and so cannot be reliably predicted.

Furthermore, this monitoring is preferably performed for each symbol in the signal 30.

In this way, the unpredictability of the ends of the communication sessions 32 does not affect the ability to guarantee delivery of data.

Referring to Figure 4, an example method of determining the reliability of each received symbol will be described.

The data transmitter 6 is preferably adapted to transmit a signal 30 that is modulated using overlapped pulse position modulation (OPPM). In such a modulation scheme, the symbols are represented by pulses 40, 41 that have a constant length and are separated from one another.

The data receiver 7 is adapted to detect both the rising edge and the falling edge of each s of the (candidate) pulses 40, 41, and to determine the time Di between successive rising edges and the time D2 between two successive falling edges. If successive pulses 40, 41 -11-have the same width, then the times Di, D2 are equal. Thus, the times Di, D2 can be compared and the condition of the signal 30 can be determined as suitable for a communication session 32 if the difference between the times Di, D2 is smafler than a suitable predetermined value. Here, the predetermined value determines the BER achieved in the communication session 32.

In this way, the method enables real-time, symbol-by-symbol channel condition monitoring. As will be explained in more detail below, this can be used as a software hitch for beginning or ending the communication sessions 32.

The method will be referred to as a "dual detection identification" (DDI) method.

In other examples, the conditions of the channel maybe monitored in other ways.

i Referring to Figure 5, an example method of communication between a data transmitter 6 and a data receiver 7 will now be described.

The communication is preferably half-duplex. In this way, a receiver is not blinded by the light of the transmitter on the same device.

As mentioned above, the data transmitter 6 is preferably adapted to have a lower power consumption than the data receiver 7. Accordingly, the communication method seeks to minimize the transmissions by the data transmitter 6.

At steps S5oa and S5ob, a communication session 32 is not underway. For example, a previous communication session 32 may have ended and a next communication session 32 may not have started.

At step S51, the data receiver 7 transmits a search signa' 3oa. An example search signal 3oa will be described bdow. The search signal oa is sent repeatedly by the data receiver 7 until the data receiver 7 begins to receive a data frame 3ob from the data transmitter 6 (see step S55, described below).

Concurrently, the data transmitter 6 listens for a search signal oa and, at step S52, it s receives one of the search signals oa transmitted by the data receiver 7 at step Si.

-12 -At step S53, the data transmitter 6 emp'oys the DDI method to determine if each of the symb&s that make up the received search signal oa are sufficienfly reBabe. If the symb&s are not sufficienfly reBabe, for examp'e because there is not a sufficient Bre of sight between the data transmitter 6 and the data receiver 7, then steps S52 and S53 are repeated. If the symbols are sufficiently reliable, then the operation of the data transmitter 6 proceeds to step S54.

At step S54, the data transmitter 6 begins a communication session 32 and transmits a data frame 30b. An examp'e data frame 30b will be described below.

At step S55, the data receiver 7 receives the data frame 30b that was transmitted by the data transmitter 6 at step S54.

At step S6, the data receiver 7 employs the DDI method to determine if each of the symbols that make up the data frame 30b are sufficiently reliable. If the symbols are not sufficiently reliable, then the operation of the data receiver 7 returns to step S51 and the transmission of the search signa's oa is restarted. If the symbols are sufficienUy reliable, then the operation of the data receiver 7 proceeds to step S57.

At step S57, the data receiver 7 begins the communication session 32 arid transmits a confirmation frame 30c. An example confirmation frame 30C will be described below.

The confirmation frame 30C is for indicating to the data transmitter 6 that the data in the data frame 3ob has been received and hence that it may transmit the next part of the data.

In other examples, confirmation frames oc may not be transmitted.

At step S58, the data transmitter 6 receives the confirmation frame 30C that was o transmitted by the data receiver 7 at step S57.

At step S59, which wifi be explained in more detail bdow, the data transmitter 6 determines if the received frame oc is an instruction frame. If so, then the operation of the data transmitter 6 returns to step S54. If not, then it proceeds to step S6o. In other examples, step S59 maybe omitted.

-13 -At step S6o, the data transmifter 6 emp'oys the DDI method to determine if each of the symb&s that make up the received frame 30C are sufficienfly r&iable.

If the symb&s are not sufficienfly reBabk, then the data transmitter 6 ends the communication session 32 and ends operations at step S67b. Thus, the data receiver 7 will not receive any further signals from the data transmitter 6 and, after a certain timeout period, will thus also end the communication session 32 and end operations.

If the symbols are sufficiently reliable, then the operation of the data transmitter 6 io proceeds to step SM.

At steps S61 to S66, data frames 30b and confirmation frames are repeatedly transmitted, received and checked for reliability as described above. The operations and the communication session 32 continue until either the data transmitter 6 or the data receiver 7, emp'oying the DDI method, determines that one of the received symbols is not reliable. In this case, the device ends the communication session 32 and ends operations at step 867a or S67b, while the other device does the same at step S67a or S67b after the timeout period, as described above.

The operations can then begin again at steps S5oa and Sob.

Referring to Figures 6(a) to 6(d), examples signals 30 transmitted by a data transmitter 6 and a data receiver 7 during communication will now be described.

Figure 6(a) illustrates example search signa's 30a transmitted by the data receiver 7.

Each search signal includes a b'ock 6o1 consisting of 8 symbcils of identica' on-off pulses with, for examp'e, a 50% duty cycle. The b'ock 6o1 is followed by a space 6i with a length of three symbols. This space 61 is to allow time for the data transmitter 6 to respond by beginning to transmit a data frame 30b. After the space 61, a further search so signa' consisting of a fuither b'ock 602 is transmitted, and so forth.

Figure 6(b) illustrates an examp'e data frame 30b transmitted by the data transmitter 6. The data frame 30b includes a sync symbol 62, a sequence/instruction symbol 63 and a payload 64 consisting of 6 symbols of data.

-14 -Figure 6(c) ilhistrates an example confirmation frame 30c. The confirmation frame 30C includes a sync symbol 65 and a sequence/instnuction symbol 66k, 662, which is repeated twice. This redundancy is to try to prevent an error in either symb& from causing a loss of sequence, and to provide enough symbols for the data transmitter 6 to perform the DDI method.

In other examples, the signals 3oa, sob, 3oc may take different forms. For example, each of their parts may include different numbers of symbols.

io The data frame oa and the confirmation frame 3ob preferably include sequence numbers 67. The data transmitter 6 is preferably adapted to transmit each successive part of the data with an appropriate sequence number 67. As illustrated in Figure 6(d), the sequence number 67 may consist of two bits. The numbers "of', "io" and "ii" may be used as the sequence numbers in a loop, while "00" may be used to indicate that the i frame is an instruction frame, as will be explained in more detail below.

In this way, complete sets of data can be more reliably communicated. For example, in the event that a data receiver 7 receives a data frame 3oa and transmits a confirmation frame 30h but this is not received by the data transmitter 6, e.g. because the line of sight was lost, the data transmitter 6 will subsequently re-transmit the same data frame 30b. From the sequence number 67 of this frame 3ob, the data receiver 7 can determine that it is the same as a frame ob that has already been received and thus can discard it. The data receiver 7 can then transmit a confirmation frame oc in order to cause the data transmitter 6 to transmit the next data frame 30b in the sequence.

Further errors in the sequence numbers 67 are preferab'y hanWed as follows. The data receiver 7 is preferably adapted to ignore a first erroneous (e.g. unexpected) sequence number, which may be merely due to noise. However, in response to two or more successive erroneous sequence numbers, the data receiver 7 is preferably adapted to o transmit an instruction frame soc. In response to receiving the instruction frame oc from the data receiver 7, the data transmitter 6 is adapted to revert to a predetermined previous point in the transmission of the data. This is ifiustrated at step S59 of Figure 5. The first data frame that the data transmitter 6 then transmits will have its sequence/instruction bits set to "00" to indicate this.

-15 -(/4 \ The communication is preferably performed using 2 OPPM, in which case the two-bit sequence number 67 correspond to a single symbol.

In other examples, the sequence numbers 67 may take different forms and, for example, may include more bits.

In other examples in which the data transmitter 6 is adapted to merely transmit the data from the one or more sensors in a continuous stream, several of the above steps may be omitted. For example, there may be no need for the search signals oa and/or io the confirmation frames 3ob and/or for the DDI method.

It will be appreciated that the above described embodiments are purely illustrative and are not limiting on the scope of the invention. Other variations and modifications will be apparent to persons skilled in the art upon reading the application.

For example, the data communication apparatus may be used in other applications, such as traffic monitoring.

The disclosure of the application should be understood to include any novel features or any novel combination of features either explicitly or implicitly disclosed herein or any generalization thereof and during the prosecution of the present application or of any appBcation derived therefrom, new claims may be formifiated to cover any such features and/or combination of such features.