CA2215817A1 - Circuit arrangement for and a method of producing a plurality of analog signals - Google Patents

Abstract

In a circuit arrangement and a method for producing a plurality of analog signals which vary in dependence on the position of one of two mutually movable bodies relative to each other, a single sensor measuringly detects the position to be monitored. The measurement value ascertained by means of the sensor is used as the basis for producing a digital signal from which an analog signal is derived by digital/analog conversion for each of a plurality of separate receivers for controlling subsequently arranged units.

Description

~he invention concerns a circuit ~ran~ement for and a method of producing a plurality of anal~g signals which vary in dependence on the position adopted by one of t~o mutually movable bodies with respect to the otller.
In situations involviny monitoring a posi~ion by means of linear or ang~lar senders or piçk-up sensors, a problem which frequen~ly arises is th~t o~e and the same linear di~placement or rot~ry move~ent h~s ~o be evaluated in dif~erent ways, fo~ controll~ng different operating procedures.
~hu~, ~or example, the instantaneous angul~r position of the ro~ry ~ha~t of the acceleraeor pedal of a motor vehicle may be e parameter of si~nificanee simultaneously for controlling the ~uel injection p~mp, the thro~tle valv~ and/or the i~niti~n timing. In ~uçh a si~ua~ion, in gener~l quite different positio~ me~surement value r~nges are detected for the individual unit5 disposed downstream of the sensor which is sensin~ the accele~tor pedal position, and the respeç~lve analog measur~ment siynal pro~uced thereb~ is ~ed tQ a receiver assoCàated with the unit in qu~tion, in a form which is matched to the need ther~of and which differs ~reatl~ from the other a~alog signal It is possible to equip syseems of that kind with a number of position sensors, for example potentiometers, with such number cor~esponding to the number of associa~ed receivers. The posi~ion sensors ~y be ~o ~r~nged in t~rm~ of as~embly and circuit~y that they each detect ~ respective indi~idually a~soçiated position range and, upon transiting same, output a vol~age which va~ies between a ~inim-l~
value correfipondin~ to one end or limi~ of thé ran~e and a ~ximum value which represents the other end or limit of the range in question.
That opera~ing procedure however involves a number of difficulties. Thus for ex~mple even if the same analog volta~e is to be 3~ fed to each of the receivers, ~o repre6ent the 6~me measurement r~nge, the syste~ m~st in~l~de ~or each r~ceiver its own specific potentiometer or sensor in order to en~re the required freedom from reactio~ or ~eed~ack.
If different measurement ranges have to be accurately rel~ted to each other, then a high level of expenditure is necessary in order s~itably ~curately to establi~h or detect the ~e~o positions or ~ero value~ of ~he potentiometer.
Furthenmore, a potentiometer can only ever cover an angular rangc of less than 360~ sa that, in si~uations o~ use in which there is a requirement for ~easuringly monitoring larger an~l~s than this, the arrange~en~ must employ two potentiome~ers ~hich ac~ordingly have to be extremely accurately mat~hed to ea~ other and which in addition h~ve to be very precisely positioned. In prac~ice that is fre~uently n4t a 1~ vi~le option because of the high production and asse~bly costs that it involves.
In addition inexpensive potentiometers gener~lly involve lin~ar output chara~teristics so that addi~ional electronic cir~uit5 are requir~d if different chara~teristic configurations are necessary.

In accordance with the present invention in term6 o~ the circuit arrangement aspeet there is provided a ~ircuit arr~ngement for producing a plurality o~ analog si~nal~ which are variable in dependence on ~h~ position adopted by one 4f first and second mutually 20 movable bodies with respect to the other and which are adapted to be fed ~o receiver~ ~hat are ~epara~ ~rcm each other, for the control of u~equent units, including - ~ single sen~or for measurin~l~ detecting Yaid po~ition to be monitored, - a cir~uit means having an output for outputting in the form of ~ digital signal the measurement ~alue a~er~ained by mean~ of the sen~or, and - a digital/analog co~ver~er means adapted to output rOr e~ch of the receivers a suitably processed analog signsl derived ~rom the 30 digital sig~al In regard to ~h~ method aspect there is provided a ~thod of prod~ing a plurality of analog ~ignalfi which are varia~le in dependence on the position adoptod by one of first and ~e~ond mutuall~
mo~able bodie~ with respe~t ~o ~he other, wherein - said position to be monitored is measuringly detected by means of a single sensor, - a digital signal representing the measurement value ascertained by means of the sensor is produced, and - a suitably processed analog signal is derived from the digital signal for feeding to respective ones of a plurality of receivers.
As will be seen in greater detail from preferred embodiments of the circuit arrangement and method the present invention can thus provide a circuit arrangement for producing a plurality of analog signals which are variable in dependence on the position of a movable any number of mutually independent position signals derived from a movement to be monitored, at a low level of circuitry expenditure, while being of a simplified design configuration using tried-and-tested components, and affording a high degree of accuracy and resolution. The method according to the invention is simple to implement while affording accurate results over a wide range of movement, insofar as one and the same digital signal can be readily fed to any number of processing channels, without any interaction or reaction effect, while on the other hand it can be transformed into the most widely varying analog signals by means of digital/analog converters which are wired or actuated in different ways, in order thereby to simulate correspondingly different analog position sender or pick-up devices.
As already indicated above, that simulation effect can be produced either by way of the specific wiring configuration of the digital/analog converters and possibly by means of downstream-disposed, simple electronic circuits or, preferably, by virtue of a procedure whereby the digitized measurement signal outputted by the sensor is modified by means of a computing and control circuit in such a way that only one digital/analog conversion operation is necessary to obtain the desired analog output signal. That modified digital signal can then be fed in a time multiplex procedure to a plurality of mutually parallel digital/analog converters, the outputs of which once again simulate the widely different analog sensors.

CA 0221~817 1997-09-19 This last-mentioned mode of oper~tion 4ffords ~he advantage that different sensors can be successivçly eimulated at one and the ~ame output in dependence on a program which is predetermined by the computin~ circuit, or in dependence on a comman~ sign~l which can be supplied ~rom the exterior.
The mo~t important parameters which in this respec~ a~e freely seleceably v~riable ~re the measurement range, the output si~nal ranges (in rçspect of current or voltag~), the association sign be~we~n those two range~, the characteri~tic configuration, and so forth.
As the s~gnals of all simulat~d outputs are derived from one and the s~me digital signal they are precisely related to ea4h other at ~ny time and it i~ readily possible ~o establish ehe con~on z~ro point therrof, If the ~ingle sensor used is an inductiv~ m~asurement value ~ender, as is to 4e found for ~xample in German patent specifications ~os 41 13 7~5 and 41 ~7 209 to which referenoe is there~ore directed here, it is possible to detect angul~ ranges of virtually any magnitude, with a s~bstantially higher de~ree of accuracy an~
resolution than is pos~ible when u~ing potentiometers.
Z~ In addition, in accordance with a preferred f~ature of the invention, ~he ~ircuit arrangement of the invention may also ha~e at least one further o~put at which the digital measurement signal itself or di~ital signals derived theref~om ~rç available.
Therefore, not only is the n~mber c~ sensors required red~ced 2S to ~ single sensor, but the arrangPment and met~od according to the inv~ntion also ~,liminAte the assembly complication~ and expenditure involved in positioning and adjusting rel~.tive to each other the plurality of sensors which were necessarily used hitherto.
An embodiment o~ the circuit arrangement and the method acçording to the present invention will now be descri4ed by way of example with reference to the singl~ Figure of the accompanyin~ drawing showing a diagrammatic view of the basic circuit diagram of ~he circuit arrangemçnt in acCordance with the invention.
~èferring to th~ Figure, reference numeral 1 ther~in denotes a circuit arrangemsnt ~or producing a plurality of analog signals which a~e variable in dependence on the position adopted by one of ~irst and seçond mutu~lly movable bodies (not shown) with respect to the other, and which a~e adapted t~ be fed to receivers ( also ~ot shown ) that are separate ~rom ea~h other, for the control of downstream-disposed or ~ubsequent uni~s. ~eferen~e numeral 2 ~n the Figure indicates a sensor which for example may be an inductive posi~ion pic~-up device, in particular an ind~ive angular pick-up devi~e.
Connected to the output side of the sensor 2 i an electronic circuit unit 3 which proce6ses the an~log 5ign~1 firstly produced by the sensor 2 and fed to the unit 3, in digitAl ~orm. A suita~le circuit configuration of this kind, for s~c~ ~ purpo~e. can be found for exa~ple in European specification ~o 0 582 lll A.
The sign~l which is outputted by the çircuit unit 3 on the ~ata bus line 4 and whiçh represents in digital form the measure~nt valu~
iS respeetively a~certained by the sensor 2 is fed di reetly to the outputs 7 and ~ o~ ~e ¢ircuit arran~ement 1. The outpu~s ~ and 8 are each connected to a respective u~er cireuit (no~ shown~ which is designed Sor receiving and further processing o~ digi~al me~surement si~nals of that natu~e.

2~ In çomparison, the ~urther ou~puts indicated at 9 through lZ
are connected to receivers or user ~ircuit5 to which measurement signals have ~o be fed in analog form~ In campa~i~on once a~ain, the ~urt~er outputs 13 and 14 service receivers to which admittedly digital siynals also have ~o be supplied, whi~h signals however are not 2S identic~l to the measurement signal delivered at the output of the ~irçuit unit 3 but ~re derived therefrom in a manner which will be described in greater d~tail bereina~ter.
The di~ital measuremen~ signal which occurs on the data bus line 4 is also fed to first and second digital/analog con~erters 16, 17 which, in accordanee wi~h a respective specification predet~rmined by fixed wiring configur~tion thereo~, convert the si~nal into an analog ~ignal which thus appears ~t the respective outputs ~ and 10.
I~ Will ~e noeed ae this po~n~ that the foregoin~ term ~ spe~ification' is used to denote for exampl~ a given mea~emen~ value 3S r~n~e, a volta~e or current range corresponding to th~t measurement value range, and 50 fo~th.
For example, if the sensor 2 is an angular pick-up de~1ce, ~oltage values of between -3 ~nd ~V may occur at the output 9 when the angular positi~n of a shaft which is being monitored by the sen~or 2 v~ries beeween 45~ an~ 65~, while the volta~e ~ppearing at the output 10 varies between ~2 and +loV if the component being deeee~ed by t~e sen~o~ 2 passes ~hrough an angular ra~ge of between 345- and S~ or -15 a~d IS~.
I~ will be appreciated that ~he foregoing numerical values are employed here only 4y way of example, and it is to be expres~ly poin~ed out that it is algo possible for the digital~an~log converters to be fixedly programmed in sueh a w~y that voltage values which are dif ~eren~, in ~erms o~ th~ m~x; m~m amp~itude or sign, may be a5so~ia~ed wit~ ~h~ analog 4utput signals of the di~i~al~analog converters, when lS passin~ through equal measurement range~, or equal voltage values are associated ~herewi~h ~hen passing ~hrough equal or ~ifferent measurement ranges. Ins~ead o~ a voltage, it is also possible, by vir~ue 4f the digital/analog converters 1~, 17 being o~ a ~ui~abl~
structure, to output an impressed current ~hich varie~ with the position to be monitor~d.
It should also be exp~e ~ly not~d that the number of digit~l/analog conver~ex unit~ which can be connected in that way to the data bus line 4 is not limited to two but çan be o~ virtually any number in order to produce the most widely varying output signals.
I~ oomparison, th~ digital measurement signal outputted ~y the output of the circuit unit 3 is ~ed to ~he digi~alfanalog ~onve~e~5 18, lg servicin~ the output~ 11 and 1~, not directly but by ~y o~ a control and co~puting uni~ as indicate~ at 20, which can be referred to as a proces~or, which proeesses that digital signal i~ acoordance with 3n the above-mentioned specifi~a~ions which are pred~t~rmined by the fixe~
wiring configuration~ in respect o~ the digital/analog conv~ers 16, 17, in su~h a wa~ that it only has to be converted into analog fon~ by the oonver~ers 18, 1~, A corresponding ~onsideration al~o applies in regard to the digit~l signals which occur at ~he outputs 13, 14 and which ~re derived from the output ~ignal on the dat~ b~s line 4 by the processor 20 in a freely jele~table manne~, for exampl~ in such a way that a single dlta pulse always appears a~ t~e output 13 when one of ~he mutually movablé
bodies reaches or passes a given, preselected position. If that posi~ion is an ang~lar posi~ion, a revolu~ion counter ~an be connected eo the output 13. The position slgn~1 delivered thereby c~n ~l~o be used ~o ~imuldte a limit po~ition switch.
At i~s output, the co~puting and control aircuit or pro~essor ineludes a ~ultiplexer ~not shown) whieh feed~ the su~tably processed di~ital signals to the downstream-disposed digital/an~log converters 18, 19 and to the outputs 13, 14 in ~ time-multiplex mode.
The ~rran~ement mAy include buffer circuits (also not shown) whieh provid~ for intermediate storage of the respective value for the digital/analog eonvertar units 18, 1~ and the outputs 13, 14 rG~peotively, for the periods of time in whi~h they are not diree~ly actuated by the proçessor ~0.
The proce~sor 20 is connec~ed ~ way of a line indicat~d 3t ~2 to the ~ensor 2 or the cir~uit uni~ 3 thereof, ca that it can also in~luence the fo~m of the digital signal outputted by the circuit unit 3 on the data bus line 4. For example, it c~n provide ~at only the in~remental variation value~ of the measurcm~nt 6i~nal, ~ measurement signal which i~ reduced in respect of its bit length by the least significant ~it, or only the direction of variation of the siynal, are outputted on ~e bus line ~.
Reference numeral 24 in the Figure denotes an input terminal 24 f~om which th~ processor 20 can be oontrolled from the extorior i~ such a way ~h~t it varies the digital signals for the individ~al downstream-d~sposed unies or output~, which ~ignals are outputted at the output of the processor 20 and are derived from the digital ~easure~ent signal on the data ~us line 4, not only in ~cordance wi~h t fixedly stored program but also in dependen~e on ~ control ~ignal whi~h is supplied there~ore by way of ~he input ter~inal 24.
The described arrangement thus ~akes it possible, by means of the digi~ized measurement signal that i~ produced by a jingle po~ition pick-up or sen~or, to service a pluralitr of digital and analog channels to which the measurement s~nal can be fed either directly or in the widely v~rying analog variants. The circuit arrange~ent thus p~rmits computer ~imulation of a widely varying range o~ kinds o~
measurement value sensors which are adapted in the optimum manner to the requirements of the respective downstream-çonnected receiver. As all sign~ls s~pplied to such re~eive~s originate from a sin~le sensor, there is no need for ~utudl adju~tment upon as~embly o~ the system.
Instead of an inductiva position ~en~or ~, it is in principle al5o possible to use a poten~iomete~ o~ any othe~ kind of positi~n 10 sen~or which produces an analog measurement sign~l Whic~ is fir~ely digi~ized in the circuit unit 3. Pote~tiometers used as ro~ary 5ensors however euf~er ~rom the dis~dvantase that they can only cover ~n an~ular ran~e of less than 360~, If the system is re~uired to measu~ingly detect ~nd tra~k a larger angular range or any number of ~evolutions, the above-mentioned inductive sensors are aocordingly to ~e pre~erred.
It will be appreciated that ~ ~irçuit arrangemOEnt according ta the invention can al~o include only fixedly wi~ed ~igital/ànalog converters or only converters which are controlled by way of a p~o~e~sor as indieated at ~0.
It will be ~ur~her appreçiated that the a40~e-described çircuit arrangement and the method of producing a plurality of analog signals implemented the~ein have been ~et fo~h only b~ wa~ of example an~
illu~tratiG~ o$ the prlncipl~s o~ the present invention and tha~
vario~s other modifications and alter~tions may be made therein without departing from the spirit and s~ope of the invention.

Claims (30)

1. A circuit arrangement for producing a plurality of analog signals which are variable in dependence on the position adopted by one of first and second mutually movable bodies with respect to the other and which are adapted to be fed to receivers that are separate from each other, for the control of subsequent units, including - a single sensor for measuringly detecting said position to be monitored, - a circuit means having an output for outputting in the form of a digital signal the measurement value ascertained by means of the sensor, and - a digital/analog converter means adapted to output for each of the receivers a suitably processed analog signal derived from the digital signal,

2. A circuit arrangement as set forth in claim 1 wherein the digital/analog converter means is adapted to output analog signals derived from the digital signal and associated with different position measurement ranges.

3. A circuit arrangement as set forth in claim 2 wherein the digital/analog converter means is adapted to output analog signals which are derived from the digital signal and which pass through different voltage ranges when the position measurement range associated with the said analog signals is transited.

4. A circuit arrangement as set forth in claim 2 wherein the digital/analog converter means is adapted to output analog signals which are derived from the digital signal and of which at least one, within a said position measurement range associated therewith, represents said measurement value in the form of an impressed current.

5. A circuit arrangement as set forth in claim 3 wherein the digital/analog converter means is adapted to output analog signals whicha re derived from the digital signal and which have a different characteristic configuration.

6. A circuit arrangement as set forth in claim 4 wherein the digital/analog converter means is adapted to output analog signals which are derived from the digital signal and which have a different characteristic configuration.

7. A circuit arrangement as set forth in claim 1 which further includes at least one output for outputting a digital measurement signal to a receiver.

8. A circuit arrangement as set forth in claim 1 which includes a multiplexer adapted to make available at least first and second ones of said analog signals in succession in respect of time at one and the same analog output of the circuit arrangement.

9. A circuit arrangement as set forth in claim 1 which includes at least first and second analog outputs at which at least first and second ones of said analog signals are available at the same time.

10. A circuit arrangement as set forth in claim 1 wherein the sensor is an inductive angle sensor.

11. A circuit arrangement as set forth in claim 1 wherein the sensor is an inductive linear sensor.

12. A circuit arrangement as set forth in claim 1 wherein the digital/analog converter means is operable to derive the analog signal for at least one of the receivers from the digital signal in accordance with a specification which is predetermined by a fixed wiring configuration.

13. A circuit arrangement as set forth in claim 1 which includes a control and computing unit which is operable to feed variably in respect of time the digital/analog converter means with digital signals which are derived from the digital signal and which are modified for the production of the desired analog signals.

14. A circuit arrangement as set forth in claim 13 wherein the control and computing unit comprises a control input by way of which the modified digital signals fed to the digital/analog converter means by the control and computing unit are variable from the exterior.

15. A method of producing a plurality of an log signals which are variable in dependence on the position adopted by one of first and second mutually movable bodies with respect to the other, wherein - said position to be monitored is measuringly detected by means of a single sensor, - a digital signal representing the measurement value ascertained by means of the sensor is produced, and - a suitably processed analog signal is derived from the digital signal for feeding to respective ones of a plurality of receivers.

16. A method as set forth in claim 15 wherein different position measurement ranges are associated with the analog signals derived from the digital signal.

17. A method as set forth in claim 15 wherein analog signals derived from the digital signal pass through different voltage ranges when the position measurement range associated with said analog signals is transited.

18. A method as set forth in claim 15 wherein at least one of the analog signals derived from the digital signal represents the measurement value in the form of an impressed current.

19. A method as set forth in claim 17 wherein the analog signals derived from the digital signal have different characteristics.

20. A method as set forth in claim 18 wherein the analog signals derived from the digital signal have different characteristics.

21. A method as set forth in claim 15 wherein a said digital signal is outputted to at least one receiver.

22. A method as set forth in claim 15 wherein at least first and second ones of said analog signals are made available in succession in respect of time at one and the same analog output.

23. A method as set forth in claim 15 wherein at lea t first and second ones of said analog signals are simultaneously made available at first and second separate analog outputs.

24. A method as set forth in claim 15 wherein the analog signal for at least one of said receivers is derived from the digital signal in accordance with a specification which is predetermined by a fixed wiring configuration

25. A method as set forth in claim 15 wherein a modified digital signal derived from said digital signal representing the measurement value is fed to digital/analog converter means for producing the analog signal for at least one of said receiver.

26. A method as set forth in claim 15 wherein a plurality of modified digital signals derived from said digital signal representing the measurement value are fed in a time multiplex process to a digital/analog converter means for producing a plurality of different analog signals.

27. A method as set forth in claim 26 wherein the sequence of said modified digital signals is controllable from the exterior.

28. A method as set forth in claim 21 wherein the digital signal for at least one of said receivers includes individual pulses, each of which characterises the attainment of at least one predetermined position.

29. A method as set forth in claim 21 wherein the digital signal for at least one of said receivers includes individual pulses, each of which characterises the passage through at least one predetermined position.

30. Each and every novel feature or novel combination of features herein disclosed.