GB2170336A

GB2170336A - Monitoring processed signals

Info

Publication number: GB2170336A
Application number: GB08600338A
Authority: GB
Inventors: Edwin Peter Jones
Original assignee: Smiths Group PLC
Current assignee: Smiths Group PLC
Priority date: 1985-01-25
Filing date: 1986-01-08
Publication date: 1986-07-30
Also published as: FR2576730A1; GB8600338D0; GB2170336B; DE3600092A1; FR2576730B1; IT8619096A0; US4734687A; DE3600092C2; IT1188267B

Description

1 GB 2 170 336 A 1 SPECIFICATION processor meansthatis arrangedto

receivethesetof output signals from the otherof the lanes and perform Signai processing a nominally-identical function that is an inverse of the firstfunction so as to produce a respective inverse This invention relates to systems for processing 70 signal that is nominally-identicai to the respective including two signal processing lanes, and to methods input signal; a first comparator means that is arranged of processing signals in two lanes. to receive the input signal of the respective lane and The invention is more particularly concerned with the inverse signal from the second processor means systems including provision for monitoring the opera- so as to produce an output representation in respect of tion of the two lanes. 75 the comparison; and a second comparator meansthat In display systems for aircraft, or other applications, is arranged to receive the input signal of the respective it is common practice to have two signal processing lane and the inverse signal from the respective third lanes which receive nominaily-identical inputs and processor means so as to produce an output repre produce nominally-identical outputs. The outputs sentation in respect of the comparison.

maybe supplied to respective displays or one of the 80 The inverse function may include a set of inverse outputs maybe selected for supply to a single display. functions.

The inputs maybe derived from a single source or Each lane may have a respective utilisation means from respective independent sources, such as two associated therewith and preferablythe utilisation sensors arranged to sense the same variable. In this means includes display means, the said firstfunction way, by comparison techniques it is possible to detect 85 converting the input signals into display driving a malfunction and, furthermore, a degree of redun- signals.

dancy is possible if means are provided forswitching The input signals to each lane may be derivedfrom between lanes. independent sources and the system may include Conventional systems of this kind can be unduly switching means operable to switch said sources to complicated or may not be capable of indicating the 90 connection with a different one of the lanes.

origin of all the different possible malfunctions. The system may include further comparator means It is an object of the present invention to provide arranged to compare the first and second input signals improved processing systems and methods. with each other and to provide an output representa According to one aspect of the present invention tion in respect of the comparison. Preferablythe there is provided a processing system comprising two 95 system includes two further comparator means lanes, each lane including first processor means that is associated respectively with a different one of said arranged to receive respective first and second lanes, both said further comparator means providing no mina 1 ly-iclentica 1 input signals, each first processor respective output representations in respect of a means being arranged to perform a nominally- comparison between the first and second input identical firstfunction on the respective input signal to 100 signals.

produce respective sets of first and second nominally- The functions maybe performed by programming identical output signals for supply to utilisation of the first, second and third processor means, the means, at leastthe first lane including: second programming of the functions being derived indepen processor means that is arranged to receive the first dently of each other, and the first, second and third set of output signals, said second processor means 105 processor means in the first or both lanes maybe being arranged to perform a function that is an inverse provided by programming of a single processing unit of the first function so asto produce an inverse signal in the or each lane.

that is nominal ly-iclentical to thefirst input signal; The system may include monitor means arranged to third processor means that is arangedto receive the receive the output representations from said compa- set of output signals from the second of the lanes and 113 rator means.

perform a function that is an inverse of the first According to another aspect of the present inven function so as to produce an inverse signal that is tion there is provided a display system including a nominal ly-iclentical to the respective inputsignal; first processing system according to the one aspect of the comparator means that is arranged to receive the present invention and display means connected to input signal of the first lane and the inverse signal 115 receive the output signals from the two lanes.

from the second processor means so as to produce an According to a fu rther aspect of the present output representation in respect of the comparison; invention there is provided a displaysystern for an and second comparator means that is arranged to aircraft including a processing system according to receive the input signal of the first lane and the inverse the one aspect of the present invention, and first and signal from the third processor means so as to 120 second display means mounted on opposite sides of produce an output representation in respect of the the aircraft cockpit, the first and second display means comparison. being connected to receive respective output signals Preferably both the first and second lanes include a from the two lanes.

respective second processor means that is arranged According to yet another aspect of the present to receive the respective first and second sets of 125 invention there is provided a method of monitoring outputsignals, each second processor means being first and second nominally-identical input signals arranged to perform a nominally-identical function comprising the steps of: performing independent that is an inverse of the firstfunction so as to produce a norninally- identical first functions on each respective respective inverse signal that is nominally-identical to input signal to produce respectivefirst and second the first or second input signal respectively; a third 130 norninally- identical output signals; supplying said 2 GB 2 170 336 A 2 firstand second outputsignalsto utilisation means; on the respective inputto convert it into a setof performing on both said outputsignals respective graphics display driving signals. These outputsignals nominaily-identical functionswhich are inversesof are suppliedvia line 106,206to the respective display the first functions, so asto produce respective inverse unit 100, 200.The output signals are also supplied to signalswhich are nominally-identical to saidfirstand 70 an inverting processor 107,207 in the respective second inputsignals; comparing the inversesignals signal generating unit 101, 201, andto another derivedfrom thefirst inputsignal with thefirstinput inverting processor 208,108 inthesignal generating signal so asto producea firstoutput representation in unitof the other lane. Each inverting processor 107, respectofthe comparison; and comparingthe inverse 207,108 and 208 performs a function on the signals signals derived from the second input signal with the 75 supplied to it that is an inverse of the respective first input signal so as to produce a second output function performed by the processors 105 and 205. In representation in respect if the comparison. this way, the set of output inverse signals from each The method may include the steps of performing on inverting processor 107, 207,108 and 208 are each both said outputsignals respective nominally-identic- nominally-identical to the input signal supplied to the al independent functions which are inverses of the 80 processors 105 and 205, and nominal ly-identical to firstfunctions; comparing a second of the inverse each other. Any difference between these signals signals derived from the first input ' signalwiththe greaterthan a permitted threshold thatallows for second inputsignal so asto produce a third output computional errors and time delays, indicates a representation in respect of the comparison; and malfunction somewhere in the processing system or comparing a second of the inverse signals derived 85 the sensors.

from the second input signal with the second input The input signals are compared with the inverted signal so as to produce a fourth output representation signals by means of comparators. Each signal gener in respect of the comparison. Preferablythe method ating unit 101, 201 includes two comparators 110, 111 includethe steps of comparing the firstand second and 210,211. One comparator 110, 210 in each unit input signals and deriving a fifth output representa- 90 receives, atone input, the input signal online 102 and tion in respect of the comparison. 202 respectively and, at its other input, the set of A display system for an aircraft, including a inverted output signals from the processor 107 and processing system, and its method of operation, in 207 respectively which are derived from the input accordancewith the present invention, will now be signal in the respective lane. The other comparator described, byway of example, with reference to the 95 111,211 in each unit also receives, atone input, the accompanying drawings, in which: inputsignal on line 102 and 202 respectively, but Figure 1 showsthe displaysystern schematically; receives, at its other input,the setof inverted output and signals from the processor 108 and 208 respectively Figure 2 shows the system in greaterdetail. which are derived from the input signal in the other The display system includes a processing system 1 100 lane. Each comparator 110, 111, 210 and 211 supplies and two display units 100 and 200 that are mounted on an output representation indicative of the comparison opposite sides of the aircraft cockpit, for providing it performs, via line 120,121,220 and 221 respectively flight information to both pilots. The display units 100 to a monitor unit 30.

and 200 receive signals from respective lanes 10 and The monitor unit30 may include a display itself or 20 in the system that operate independently of one 105 supplysignals to the display units 100 and 200 so that another butthe operation of which is continuously or an indication of correct functioning or malfunctioning intermittently compared and monitored. The display is provided. The monitor unit 30 may also control system also includes two independent signal sources switching of elements within the system so that 103 and 203 that supply nominally-identical signalsto identified malfunctioning elements are disconnected the processing lanes 10 and 20 respectively. The 110 and both displayunits 100 and 200 are supplied with sources 103 and 203 may be sensors responsiveto, for correctsignals.

example, pitch attitude, roll attitude, heading, localis- The inputsignals referred to above are from erand glide deviation oraltitude. Each lane 10 and 20 independent nominally-identical sources 103 and 203 includes a signal generating unit 101 and 201 respec- although they could be from the same source. In the tively that processes the sensor outputs to produce a 115 arrangement shown in the drawings, each lane 10, 20 set of suitable graphics display driving signals for includes a switch 130 and 230 which is operable to display on the respective display unit 100 or 200. connectthe input lines 102 and 202 to one or other of A monitoring operation is performed by each lane the sources 103 and 203. The two switches 130 and 230 by, firstly, comparing the output signals, after suitable are preferably ganged together so that, at anytime, transformations, with the corresponding input signal, 120 the input signals to the two signal generating units are so as to monitorthe functional integrity of the derived from different ones of the sources 103 and respective signal generating unit, and secondly by 203. Switching of the two switches 130 and 230 is comparing the output signals, aftersuitable trans- controlled by a switching control unit 40.

formations, from one lane with the corresponding Each lane 10, 20 may also include a further signal in the other lane, so as to monitorthe nominal 125 comparator 140, 240 which compares the signals from equality of the two lanes. the two sources 103 and 203 with each other and Each signal generating unit 101 and 201 includes a supplies respective output representations to the processor 105,205, which receives as an input, a monitorunit30.

signal from the appropriate source 103,203 via line In practice, the processors 105,107 and 108 and the 102,202. The processor 105,205 performs a function 130 processors 205,207 and 208 are not provided by one 3 GB 2 170 336 A 3 ormore processing units orcomputers in each lane generation of processed data signals such as in an air which is programmed to perform, in combination, the data computer.

Claims

function bywhich the graphics display command CLAIMS signals and thetwo

sets of inverse functions are 1. A processing system comprising two lanes, derived. These processing units orcomputers are 70 wherein each lane includes first processor means that constituted bythe signal generating units 101 3nd 201 is arranged to receive respective first and second which can also each perform thetwo comparisons nominally-identical inputsignals, each first processor described above as being performed bythe comparameans being arrangedto perform a nominally tors 110 and 111, and 210 and 211. Itwill be identical firstfunction on the respective inputsignal to appreciated therefore that, in practice, a malfunction 75 produce respective sets of first and second nominally of the signal generating unit 101 or 201 will affect the identical output signals for supply to utilisation functions performed by all three of the processing means, wherein at leastthe first lane includes: second units described. processor means that is arranged to receive the first If we considerthe outputs of only the comparators set of output signals, said second processor means 110and111 in one lane 10, it is appareritthatthey can 80 being arranged to perform a function that is an inverse indicate four different states, as follows: of the firstfunction so as to produce an inverse signal 1) both comparators indicating similar inputs; that is nominally- identical to the first input signal; 2) comparator 110 indicating similar inputs, compathird processor means that is arranged to receive the rator 111 indicating differing inputs; set of output signaisfrom the second of the lanes and 3) comparator 110 indicating differing inputs, 85 perform a function that is an inverse of the first comparator 111 indicating similar inputs; function so as to produce an inverse signal that is 4) both comparators indicating differing inputs. nominally-identical to the respective inputsignal; first In state 1) the signal generating unit is operating comparator meansthat is arranged to receive the correctly and no action need be taken. input signal of the first lane and the inverse signal In state 2) the output supplied to the display 100 is 90 from the second processor means so as to produce an consistentwith the input signals on line 102, butthe output representation in respect of the comparison; output of the inverse processor 108 is inconsistent and second comparator means that is arranged to with the input signals on line 102. Since the output of receive the input signal of the first lane and the inverse the comparator 110 indicates that units 105 and 107 signal from the third processor means so as to are performing correctly, the unit 108 may be functionproduce an output representation in respect of the ing correctly becausethe function carried out by this comparison.

unit is in fact carried out in the same unit that carries 2. A processing system according to Claim 1, out the othertwo functions. This thereby indicates that wherein both the first and second lanes include a there is disagreement between the inputs supplied to respective second processor meansthat is arranged the two lanes 10 and 20. 100 to receive the respective first and second sets of In state 3) the output signal supplied to the display output signals, each second processor means being is inconsistent with the input signal on fine 102 arranged to perform a nominal ly-iclentical funclion supplied to the unit 101, but is consistent with the that is an inverse of the firstfunction so as to produce signal supplied to the display 200 in the other lane 20. respective inverse signal that is nominally-identical tu This indicates a failure in unit 101. 105 the first orsecond input signal respectively; a third In state 4) the output signa! supplied to the display processor means that is arranged to receivethe set cf is inconsistent with the input signal supplied to the output signals from the other of the lanes and perform unit 101, and is inconsistent with the signal supplied to a nominally- identical function that is an inverse of the the display200 bythe other unit 201. This indicates firstfunction so as to produce a respective inverse thatthere is a common mode failure of the units 101 110 signal that is nominally-identical to the respective and 201 thereby causing the monitor unit 30 to input signal; a first comparator means that is arranged produce a display "SGU FAIL". to receive the input signal of the respective lane and The invention thereby provides monitoring of the inverse signal from the second processor means so as actual displayed values, ratherthan merely input to produce an output representation in respect of the values. By utilising the indications from each compa- 115 comparison; and a second comparator means that is rator 110,111,210,211,140 and 240, the monitor unit 30 arranged to receive the input signal of the respective can detect a wide range of faults and produce an lane and the inverse signal from the respective third appropriate display message. In many cases, the fault processor means so as to produce an output repre can be diagnosed in such a way as to allcw recon- sentation in respect of the comparison.

figuration of the system from operative units, or 120 3. A processing system according to Claim 1 or2, enable the userto identify and use correctly function- wherein the said inverse function includes a set of ing parts of the system. inverse functions.

In orderto eliminate the possibility of programming 4. A processing system according to anyone of the commom-mode errors, the programming of the preceding claims, wherein each lane has a respective function and the inverse function are developed 125 utilisation means associated therewith.

independently ot one another. 5. A processing system according to anyone of the The invention is not limited to use in display preceding claims, wherein the said utilisation means systems but could be eryiployed where output signals includes display means, and wherein the said first are derived from two lanes, such as, for example, for function converts the input signals into display driving use in performing a control function or inthe 13-1 signals.

4 G13 2 170 336 A 4 6. A processing system according to anyone of the to produce a second output representation in respect preceding claims, wherein the input signals to each of the comparison.

lane are derived from independent sources. 18. A method according to Claim 17, including the 7. A processing system according to Claim 6, steps of: performing on both said output signals wherein the system includes switching means oper- 70respective nominal ly- identical independent functions ableto switch said sourcesto connection with a which are inverses of the first functions; comparing a different one of the lanes. second of the inverse signals derived from thefirst 8. A processing system according to anyone of the input signal with the second input signal so as to preceding claims, wherein the system includes further produce a third output representation in respect of the comparator means arranged to compare the first and 75 comparison; and comparing a second of the inverse second input signals with each other and to provide an signals derived from the second input signal with the output representation in respect of the comparison. second input signal so as to produce a fourth output 9. A processing system according to Claim 8, representation in respect of the comparison.

wherein the system includes two further comparator 19. A method according to Claim 17 or18, means associated respectively with a different one of 80 including the steps of comparing the first and second said lanes, and wherein both said further comparator input signals and deriving a fifth output representa means provide respective output representations in tion in respect of the comparison.

respect of a comparison between the first and second 20. A method substantially as hereinbefore de inputsignals. scribed with reference to the accompanying drawings.

10. A processing system according to anyone of 85 21. Any novel feature or combination of features the preceding claims, wherein the said functions are as hereinbefore described.

performed by programming of thefirst, second and third processor means, and wherein the programming Printed in the United Kingdom for Her Majesty's Stationery Office, 8818935, 7/86 1 8996. Published at the Patent Office, 25 Southampton Buildings, of thefunction is derived independently of each other. London WC2A 1AY, from which copies may be obtained.

11. A processing system according to anyone of the preceding claims, wherein the first, second and third processor means in the first or both lanes is provided by programming of a single processing unit in the or each lane.

12. A processing system according to anyone of the preceding claims, including monitor means, said monitor means being arranged to receive the output representations from said comparator means.

13. A processing system substantially as hereinb- efore described with reference to the accompanying drawings.

14. A display system including a processing system according to anyone of the preceding claims and display means connected to receive the output signals from the two lanes.

15. A display system for an aircraft including a processing system according to any one of Claims 1 to 13, and first and second display means mounted on opposite sides of the aircraft cockpit, said first and second display means being connected to receive respective output signalsfrom the two lanes.

16. A display system substantially as hereinbefore described with reference to the accompanying drawings.

17. A method of monitoring first and second nominally-identical input signals comprising the steps of: performing independent nominal lyidentica If irst functions on each respective inputsignal to produce respective firstand second nominally-identical output signals; supplying said first and second output signals to utilisation means; performing on both said output signals respective nominally- identical functions which are inverses of the firstfunctions, so as to produce respective inverse signals which are nomi- nally-identical to said first and second input signals; comparing the inverse signals derived from the first input signal with the first input signal so as to produce a first output representation in respect of the comparison; and comparing the inverse signals derived from the second input signal with the first input sigrpl so as