CA1219050A

CA1219050A - Devices for controlling electrically operated appliances

Info

Publication number: CA1219050A
Application number: CA000450321A
Authority: CA
Inventors: Walter Muller
Original assignee: Clayton Foundation for Research
Current assignee: Clayton Foundation for Research
Priority date: 1983-04-12
Filing date: 1984-03-23
Publication date: 1987-03-10
Also published as: AU565407B2; AT387714B; KR840008273A; SE458501B; GB2138545B; DK98984D0; SE8401317L; US4865610A; NL8401051A; JPS59205281A; FR2544526A1; IT8420512A0; FR2544526B1; ATA97884A; AU2669984A; ES530547A0; CH660554A5; ZA842177B; GB2138545A; MX156037A

Abstract

DEVICES FOR CONTROLLING
ELECTRICALLY OPERATED APPLIANCES

Abstract At least one actuating element emits a signal in response to blowing and/or suction airflow from a person and is connected to a mouthpiece, and is coupled by way of an evaluation circuit to the appliance to be controlled. In order to maximize the total number of possible combinations of control signal and/or control data, two position trans-mitters (X-pos, Y-pos) are coupled to further inputs of the evaluation circuit, which incorporates at least one micro-processor, and, when the mouthpiece is used, each transmitter emits a coordinate signal characteristic of the position of the mouthpiece in a coordinate system. The microprocessor is adapted to process the signals from the actuating element, which is in the form of an impact pressure transducer and also the coordinate signals from the position transmitters (X-pos, Y-pos) to produce control data for the appliance.

Description

~2~9050 DEVICES FOR CONTROLI-ING
ELECTRICAL~Y OPERATED APPLIA~ICES

1 Background of the Invention

2 Thi~ invention relates to devices for controlling

3 electrically operated appliances.

4 Such devices are particularly, but not exclusively, known as aids for people who are severely physically handi-6 capped (see, for example, "Paraplegia~, official organ of 7 the Swiss Paraplegic Foundation, 4055 Basle, year 7, No. 25, 8 March 1983, page 16, lower illustration and accompanying 9 caption). The ~nown devices merely serve, for example, to actuate a light switch or to trigger an alarm call for a 11 nuxse via a switching element in the form of a relay. These 12 known devices therefore merely carry out the function of a 13 simple, remote-controlled "In-Out" ~witch, or, at best, of 14 a change-over swi~ch.
Summary 16 It is an object of the in~ention to provide ~
17 device of the kind referred to initially, which requires 18 actuation simply by mean~ of the mouth of the operator, and 19 which is capable of controlling electrically operated appliance~ which are appreciably more complex than a swltch 21 or the like. In this connection, the operator - as mentioned 22 eaxlier - can be a person who is severely handicapped 23 phy~ically, e.g., a person having no arms or a paraplegic, or 24 a person who is completely or partially unable to use his/her hands to perform manual tasks. The following are given as 26 electrical appliances to ~e controlled, purely as examples 27 and without any claim to completeness: electrically oparated 28 and guided vehicles, including wheelchairs; electrically 29 powered artificial limbs; remote-controlled manipulators including industrial robot~, typewriters, calculating systems 31 including electronic computers and interactive electronic 32 data processing ~ystems. ~;

~219050 1 According to the invention there is provided a 2 device for controlling an electrically operated appliance, 3 comprising at least one actuating element which emits a 4 signal in response to blowing and/or suction airflow from a person and which is connected to a mouthpiece, the actuating 6 element being coupled to the appliance to be cor~trolled by 7 way of an evaluation circuit, wherein two position trans-8 mitters are coupled to further inputs of the evaluation g circuit, which incorporates at least one microprocessor, and, when the mouthpiece is used, each transmitter emits a 11 coordinate signal characteristic of the position of the 12 mouthpiece in a coordinate system, the microprocessor being 13 adapted to process the signals from the actuating element, 14 which is in the form of an impact pressure transducer, and also the coordinate signals from the position transmitters 16 to produce control data for the appliance.
17 The coordinate system can be an orthogonal one 18 having axes parallel to the directions of movement of the 19 mouth of the operator, these directions corresponding to swivelling movement and nodding movement of the head. Assuming 21 that, by swivelling the.head, the mouth is capable of 22 describing an arc of 20cm in length, and, by nodding the 23 head, the mouth is capable of describing an arc of 7 cm in 24 length, and further assuming that the position transmitters exhibit a resolution of 0.5cm of arc in each case, and that 26 an impact pressure transducer i8 available which emits only 27 one signal for suction and only one signal for blowing 28 airflow, the device is capable of emitting over 1000 discrete 29 signal combinations. If the mouthpiece incorporates two adjacent openings ~each leading to an impact pressure trans-31 ducer of the kind specified~ which can optionally be closed 32 and opened by the operator's tongue, and if the position ~2~9050 1 transmitters exhibit the resolution previously a~sumed, 2 the number of possible ~ignal combinatio~s is tripled.
3 In one embodiment, the mounting support supporting 4 the mouthpiece includes a rail and a sliding carriage dis-placeable along the rail with mouthpiece being connected to 6 the carria~e and being movable in a direction tran~verse to 7 the rail. In another embodiment, the mounting support 8 includes first and second parallelogram bar frames supporting g the mouthpiece and being pivotable in plane at right angles to each other, and adapted to be attached to a person's 11 body. Various types of position transmitters may be 12 provided such as light sending and receiving elements, angle 13 encoders, strain gauges, and potentiometers.
14 Other and further objects, features and advantages will be apparent from the following description of presen~ly 16 preferred embodiments of the invent~on, given for the purpose 17 of disclosure and taken in conjunction with the accompanying 18 drawings.
19 Brief Descri~tion of the Drawings Figure 1 i8 an outline view of a first embodiment 21 of that part of the device which i~ to be actuated directly 22 by the operator, 23 Figure 2 i8 an outline view of a second embodiment 24 of that part of the device which i~ to be actuated directly 2$ by the operator, 26 Figure 3 i8 a side view of the part shown in 27 Figure 2, 28 Figure 4 is a horizontal section, on a larger 29 scale, of the mouthpiece and related components of the part of Figure 1, showin~ different variants of position trans-31 mitter, 32 Figure 5 i8 a view, partly in section, in the ~2~gos0 l direction of the arrow v in Figure 4, 2 Figure 6 i8 a section taken along the line VI-VI
3 in Figure 4, 4 Figure 7 is a section taken along the line VII-~II
in Figure 4, with the ~outhpiece moved upwards from the rest 6 position and showing other variants of the two position trans-7 mitters, and 8 Figure 8 is a simplified bloc~ diagram of an 9 evaluation circuit.
Description of the Preferred Embodiments ll While the present invention will be deRcribed in 12 connection with its application as an aid for a physically 13 handicapped person, for purposes of illustration only, it 14 will be understood that the present invention may be broadly used in other applications in which a person may simply by 16 blowing and/or sucking air through a mouthpiece electrically 17 control a variety of devicQs.
18 It should fir~t be noted that the mouthpiece l9 (still to be described3 conforms to motions of the mouth and consequently of the head of the per~on operating the mouth-21 piece. Hereinafter swivelling ve~ent.(lateral movement to 22 and fro) of the head of the per~on will be designated as 23 movement in the X direction, the instantaneous position of 24 the head in this direction being defined as the X coordinate, whereas nodding movement (movement up and down) will be 26 designated as movemen~ in the Y direction, the instantaneou~
27 position of the head in this direction being defined as the 28 Y coordinate.
29 In Figure l there is shown the head lO of a person from above. The axis perpendicular to the plane af the 31 drawing, around which the head lO can swivel, is designated ll.
32 A drive motor 12 i~ mounted on a vertical axi~ in a fixed lZl9050 1 po~ition, and can be gwitched on and off by means of a switch 2 13 which can also be u8ed to change the direction of rotation.
3 The motor 12 carries a swivel arm 14 which can swivel in a 4 horizontal plane and to which a mounting support 15 having S an arc-shaped guide rail 16 is fixed. A sliding carriaqe 17 6 i~ displaceable along thi~ guide rail 16 as shown by the 7 arrows 18. In or on the ~liding carriage 17 as will be 8 described, there i~ provided a mouthpiece which the person 9 can move with his/her mouth along the rail 16, which describes an arc around the axis 11, i.e., in the X direction. If the 11 person actuates tfor example, with his/her cheek or chin) the 12 switch 13, after releasing the mouthpiece, the arm 14 dri~en 13 by the motor 12 ~wivels the mounting support 15 wlth the 14 sliding carriage 17 thereon clockwise (arrow 19) into the out-of-operation position shown ln dotted lines in the fi~ure 16 and thereby disengage~ the person'~ face. A second actuation 17 of the switch 13 brings the mounting support 15 with the 18 sliding carriage 17 thereon back lnto the operating position 19 ~hown ~n soIid lines. The embodiment depicted in ~igure 1 does not have to be mounted on a fLxed unit, e.g., a seat, on 21 which the operator is positioned, but can also be fixed to 22 the person's body. The mounting support 15 could accordlngly 23 be fitted to a frame to be fastened to the person's torso.
24 The embodiment of Figures 2 and 3 is indeed fixed ` to the person's body and consequently move~ with the latter's 26 torso. For thi~ application, a frame 20 emcompa~sing the 27 person's neck and shoulders, and anatomically fitted to the 28 wearer, is provided. The frame 20 is appropriately lashed 29 to the person's trunk with strap3 ~not shown). The parts of the frame 20 which fit over the shoulders have end members 31 23 and 24 of a first paralielogram bar frame 25 fixed thereto, 32 the end members each belng pivotable about a respective ball ~219050 1 joint 21 and 22, and the central member 26 of the parallelo-2 gram having a mouthpiece 27 fastened to it. An impact 3 pressure transducer 28, shown here in outline only in the 4 first instance, is incorporated in the mouthpiece 27. The S vertical axis of rotation 22 of the end member 24 is at the 6 same time the axis of an angle transmitter 29, e.g., of a 7 potentiometer or of an angle encoder, which thus emits an 8 electrical signal corresponding to the angle of swivelling 9 of the parallelogram bar frame 25 in the horizontal plane.
One of the end members of the parallelogram bar frame 25, 11 e.g., the end member 23, i8 for it~ part configured, as can-12 be inferred from Figure 3, a~ a parallelogram bar frame 13 that can be swivelled in a vertical plane, whose upper bar 14 actuate~ a further angle transmitter 30, which for it part emits a signal corresponding to the angle of swivelling of 16 the bar frame 23 in the vertical plane. ~he lengths of the 17 bars of the frames 23 and 25 are chosen such that moYement 18 of the mouthpiece 27, which can be fitted with a bite contact 19 31, by the person's mouth describe~ arcs which are centered on the axis 11 and the axis 32 (the axi8 of the nodding motion 21 of the head 10).
22 In addition to the signals emitted by the impact 23 pressure transducer 28, and if need be by the bite contact 24 31, the angle transmitters 29 and 30 additionaliy each emit a signal characterizing the X or the Y direction, and all these 26 signals are transmitted by a conductor cable 33 shown in 27 outline only.
28 The mouthpiece will now be described in more detail, 29 particularly as to its mode of installation in the sliding carriage 17 of Figure 1, with reference to Figures 4 to 7.
31 The mouthpiece 27 of Figures 2 to 3 in the narrower ~ense 32 can be con~igured similarly to the mouthpiece depicted in ~ I

12~9050 1 Figures 4 to 7.
2 The mouthpiece illustrated compri~es two lateral 3 lobeQ 34 and 35 shaped in the manner of a mouth ma~k, 4 which are intended to rest ully on the part~ of the cheeks S adjacent to the corners of the person's mouth. In the central 6 area between the lobes 34, 35, two blowing/suction openings 7 36 and 37 are provided, each debouching into a chamber 38 8 or 39 respectively. From each of the chambers 3~ and 39, an g air vent 40 ox 41 with a throttled, preferably adjustable throughput capacity leads out into the open. Also a connecting 11 fitting 42 or 43 is provided in each chamber 38 or 39. The 12 connecting fittings 42 and 43 connect the chambers 38 and 39 13 in each case with the one side of an impact pressure trans-14 ducer 44 or 45 (for example, ~roduct No. ~40 PC, Type D, Micro Switch Corporation) whose other side is connected with 16 the outside via a pressure equalization vent 46 or 47. Each 17 of the impact pressure transducers 44 and 45 generates a signal 18 characterizing by value and arithmetical sign the pressure 19 differential between the chamber~ 38, 39 and the outside.
As can be inferred in particular from Figures 5 21 an~ 7, the mouthpiece 27 is connected to the sliding carriage 22 17, which itself i8 di~placeable along the arc-~haped guide 23 rail 16, via two pairs of leaf springs 4B and 49 fitted one 24 above another and made from ~ynthetic material for example.
The upper and lower leaf springs 48 and 49 are fixed at 26 one end to the sliding carriage 17 and at the other end to 27 the free end regions of the side lobes 34 and 35, and 28 thereby make it possible for the mouthpiece 27 to be displaced 29 or deflected transversely to the track of the guide rail 16 and against the effect of the leaf springs, i.e., in tbe 31 Y direction. The manner in whicb this movement is detected 32 will be described below.

1~

1 The sliding carriage 17 comprises an arc-~haped 2 extension 50 which i8 T-shaped in cro6s-section and is secured 3 behind two flangeQ 51 and 52 which face ~ach other, and are 4 formed on the guide rail 16 ~ as ~hown in Figures 6 and 7.
A light source 53, which in practice takes the form of a 6 point source, e.g., a light emitting diode (LED), is fixed 7 to the extension 50. Immediately opposite the light source 53 8 are light-sensitive elements 55, e.g., phototransistors, 9 arranged on a support 54 which i~ fastened to the mounting support and consequently i8 in a fixed position relative to the 11 guide rail 16, the elements 55 being in a row concentric with 12 the arc of the guide rail 16. The light source 53 accordingly 13 forms, with the row of light-sensitive elements 55, the 14 position transmit~er for the X direction, insofar as the light source 53 is able to actuate at any given time only one 16 of the elements 55, which for its part indicates the 17 instantaneous position of the sliding carriage 17 in the X
18 direction.
19 As shown in Figure 7, the position transmitter for the X direction can alternatively be formed by a resistive 21 layer 56 running parallel to the arc of the raii 16 and swept 22 by a sliding contact 57 fixed to the extension 50. The 23 ~liding contact 57 also sweeps a 81ip ring segment 58, 24 parallel to the resistive layer 56 but insulated from it, 80 that the resi~tance value between the one end of the resistive 26 layer 56 and the slip ring seg~ent 58 depends on the instan-27 taneous position in the X directlon of the sliding carriage 28 17 and hence of the mouthp~ece 27. The layer 56, the sliding 29 contact 57 and the slip ring segment 58 thus together form a position transmitter for the X direction, which in this 31 case emits an analogue signal characterizing the X
32 position.
~3 -8-~;

~219050 1 It has already been stated that the mouthp~ece 27 2 can be moved or deflected upwards and downwards relative to 3 the sliding carriage and against the effect of the leaf 4 springs 48 and 49, that i8, transversely to the track of the rail 16. The direction of thi~ movement is the Y direction 6 (in Figure 7 the mouthpiece 27 i8 at maximum deflection 7 upwards). In order to detect this movement or deflection 8 in the Y direction, an angle encoder 59 i~ fixed to the g sliding carriage 17 in Figure 5. This angle encoder 59 can be actuated via a forked arm 60 which itself embraces a 11 pin 61 fixed to the side of the mouthpiece 27. The angle 12 encoder 59 thereby form~ the po~ition transmitter for the 13 Y direction.
14 As shown in Figure 7, the position transmitter for lS the Y direction can alternatively be formed by a potentio-16 meter which consists of a resistive layer 62 fixed to the 17 sliding carriage 17 and swept by a sliding contact 63 fitted 18 to the mouthpiece 27. The resistance value between one end 19 of the resistive layer 62 and the sliding contact 63, or alternatively the re~ultant voltage drop across the elements, 21 generates an analogue signal characterizing the instantaneous 22 position of the mouthpiece 27 in the Y direction.
23 Another form of position transmitter for the Y
24 direction is al~o shown in Figure 7 (and also in Figure 1).
When the mouthpiece 27 i~ ved or deflected transYersely to 26 the guide rail 16, the leaf springs 48 and 49 bend in an 27 "S~ shape, as ~hown in F~gure 7. This bending cause~ one 28 part of the surface of each leaf spring to stretch and 29 another part of the same surface to be compressed, the extent of stretching and/or compre~sion being a measure of the 31 deflection of the mouthpiece 27 in the Y direction. Two 32 strain gauges 65 and 66 fixed to one of the lower lea~

34 _9_ ~2~90S0 1 springs 49 may therefore serve as the position transmitter 2 for the Y direction, and may generate an analogue output 3 signal.
4 The elements located in the vicinity of the operator's

5 mouth which have been described provide the following signals:

6 - impact pressur transducer 28 and/or 44, 45:

7 pre~sure differential in one, or in two

8 separated, chambers with respect to the

9 outside (produced by blowing or suction through the openings 36 and/or 37~.
11 - angle transmitter 29 tFigure 2) or LED 53 12 and phototransi~tor~ 55 (Figure 4~ or 13 potentiometers 56, 57, 58 (Figure 7~:
14 instantaneous position of the mouthpiece in the X direction.
16 - angle transmitter 30 (Figure 3) or angle 17 encoder 59 tFigure 5~ or potentiometers 18 62, 63 (Figure 7) or strain gauges 65, 66 19 (Figures 1, 7): instantaneous position of the mouthpiece in the ~ direction.
21 - bite contact 31 tFigure~ 3 and 6): ~dditional 22 switching signal.
23 It goss without saying that these di~er~e signal~
24 have to be processed into data wh~ch i8 suitable for bringing into operation the appliance whiCh i4 to be cont~olled. `
26 Likewise it will be appreciated that the evaluation clrcult 27 required for this purpose has to be adapted not only to the 28 type of impact pressure transducer or pressure measuring cell 29 and of position transmitter, but also to the type of appliance to be controlled, and finally also to the perhaps 31 impaired abilities of the operator who is to operate the 32 device.

~2190S0 1 A possible evaluation cir~uit for this purpose i~
2 ~hown in Figure 8, and designated 64, the circuit being shown 3 in highly diagrammatic form and purely by way of example.
4 The input stage, a~ it were, of the evaluation S circuit 64 is constituted by a microprocessor 67 (e.g., 6 Motorola product type MC6805, or Intel product type 8048) in 7 which, in addition to a central processing unit (CPU), a 8 working memory (RAM), a fixed-programme memory (~OM) and 9 analogue-digital a6 well a~ digital-analogue converters with the a~sociated inputs and outputs are integrated. On the 11 input side, the follow~ng are connected to the microprocessor:
12 the impact pressure transducers 44, 45 (or 28), the position 13 transmitters for the X and Y directions ~here designated 14 X-po~ and Y-pos), and the bite contact 31 (if present).
The programme in the f~xed-pxogramme memory performs 16 the following functions in the example represented:
17 - reception of the digital and analogue 1~ signal~ whenever they are received from 19 the transmitters.
~ digitisation of the analogue signals.
21 - evaluation and processing of the digitised 22 signals into data accoxding to the require-23 ments of the appliance to be controlled, 24 and output of the data in serially coded form.
An interactive standard interface 63 of the RS232 26 type (enclosed by dotted lines in Figure 8) can be connected 27 to the microprocessor 67, or, for each direction of data 28 flow, a respective drive module 69 ~e.g., Motorola MC1488) 29 may be coupled to a respective receive module 70 ~e.g., Motorola MC1489), the coupling between the drive and receive 31 modules being either by way of a conductor or even by a 32 wire-less connection.

1 A microcomputer 71 i6 connected to the interface 68 2 or to the modules 69, 70, being o~ the one hand adapted to 3 steer (~ia a further interface 72) the applicance to be 4 controlled, and on the other hand connected to a peripheral unit, e.g., in the form of a VDU 74. ~his ~DU 74 i8 positioned 6 in the field of view ~directly or via a projection system) 7 of the operator of the device. On the VDU 74 there may appear, 8 for example, the operation~ executed by the appliance 73, 9 in textual or 5ymbol form, plus a cur~or which specifies the instantaneous po~ition of the mouthpiece 27 in the X, Y
11 coordinate system. If the cursor i8 superimposed on an 12 operational text of symbol, corresponding operation of the 13 appliance 73 can be induced, for example by blowing and/or 14 suction, in which case termination of operation i8 then also indicated on the VDU 74.
16 If, for example, the appliance i8 a typewriter 17 or an electronic data processing installation, the corres-18 ponding ~eyed input would appear on the YDU together with, 19 if necessary for the purpose of any corrections that may be required, a specified quantity of the data previously inputted.
21 As already mentioned, the evaluation circuit 64 22 has to be adapted to the kind of transmitter~ used on the 23 input side, and to the nature of the appliance to be controlled, 24 in which case the fixed programme of the microprocessor 67 and, if necessary, the programme of the microcomputer 71 26 can also be adapted to the capabilities of the operator.
27 The structure of the evaluation circuit 64 can accordingly 28 be very varied, depending on the appliance to be controlled.
29 It is important in the configuration described that, with the impact pressure transducerts), and the position trans-31 mitter~ coupled directly or indirectly to the mouthp$ece, 32 a virtually unlimited number o~ signals can be generated, ~219050 1 which can be processed into the data necessary an suitable 2 for the control of complex appliance~.
3 The device described can accordin~ly be regarded 4 as a valuable aid to ~he full reintegration and rehabilitation of people who are physically severely handicapped, and/or 6 as a contribution to the facilitation or simplification of 7 the execution of complex control processes.
8 The present invention i8 therefore well adapted 9 to carry out the objects and attain the ends and advan~ages mentioned as well as others inherent therein~ While a 11 preferred embodiment of the invention has ~een given for the 12 purpose of disclosure, numerous changes in the details of 13 construction and arrangement of parts will readily suggest 14 themselves to those skilled in the art and which are encompassed within the ~pirit of the invention and the scope 16 of the appended claims.

18 What is claimed is:

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A device for controlling an electrically operated appliance comprising, a mouthpiece adapted to conduct an air flow therethrough in response to a person blowing and/or sucking air therethrough, a pressure transducer connected to the mouthpiece and actuated by air flow through the mouthpiece, said transducer providing a signal in response to air flow, two position transmitters connected to and measuring the position of the mouthpiece in a coordinate system, each transmitter emitting a coordinate signal characteristic of the position of the mouthpiece in a coordinate system, an evaluation circuit connected to and receiving the outputs of the pressure transducer and the position transmitters, said circuit including at least one microprocessor for processing the output signals from the pressure transducer and the position transmitters, said circuit connected to and controlling said appliance.

2. The device of claim 1, including a mounting support connected to the mouthpiece which is capable of being brought into a fixed position relative to the body of an operator, and the mouthpiece is movable relative to the mounting support in two coordinate directions, each of which is detectable by the position transmitters.

3. The device of claim 2, wherein the mounting support includes a rail and a sliding carriage displaceable along the rail, the mouthpiece being connected to the carriage and being movable in a direction transverse to the rail.

4. The device of claim 3, including a row of position sensors disposed along the rail, the sensors cooperating with an element fitted to the sliding carriage and the sensors and the element together constituting one of the position transmitters.

5. The device of claim 4, wherein the other position transmitter detects movement of the mouthpiece transverse to the rail and is in the form of an angle encoder or potentiometer.

6. The device of claims 3 or 4, wherein the mouthpiece is connected to the sliding carriage by way of at least one spring element which is capable of being deformed transverse to the rail, and said other position transmitter incorporates at least one strain-gauge connected to the spring element.

7. The device of claim 4, wherein the position sensors fitted to the rail are light-sensitive elements arranged to be actuated by a light source fitted to the sliding carriage.

8. The device of claim 3, including a resistance mounted on the rail and a sliding contact on the sliding carriage coacting to form a potentiometer constituting one of the position transmitters.

9. The device of claim 2, wherein the mounting support comprises a first parallelogram bar frame, which is capable of being swivelled in a first plane and whose end members are capable of being attached to the person's body, a second parallelogram bar frame being formed by at least one of the end members of the first parallelogram bar frame and pivotable in a plane at right angles to the first plane, and the mouthpiece fixed to an intermediate member of the first parallelogram bar frame, the position transmitters being angle transmitters connected to and adapted to detect the angle of swing of both parallelogram bar frames.

10. The device of claim 9, wherein the angle transmitters are angle encoders.

11. The device of claims 1, 2 or 3, wherein the mouthpiece is provided with a bite contact which is also coupled to the evaluation circuit.

12. The device of claim 3, wherein the rail is swivelled between an operating position and a rest position by means of a swivel arm.

13. The device of claim 12, wherein the swivel arm is capable of being swung by means of a motor from the operating position into the rest position, and the motor is adapted to be switched on and off by means of a switch actuabla by the operator's head.

14. The device of claims 1, 2 or 3 including a display unit coupled to the evaluation circuit and having a cursor which, in conjunction with the operation of the appliance to be controlled, indicates the instantaneous position of the mouthpiece in the coordinate system.

15. The device of claims 1, 2 or 3, wherein the mouthpiece incorporates two blowing openings which are immediately adjacent one another and are connected to the pressure transducer whose output is supplied to an input of the evaluation circuit.

16. The device of claims 4 or 5 wherein the mouth-piece is provided with a bite contact which is also coupled to the evaluation circuit.

17. The device of claims 4 or 5 including a display unit coupled to the evaluation circuit and having a cursor which, in conjunction with the operation of the appliance to be controlled, indicates the instantaneous position of the mouth-piece in the coordinate system.

18. The device of claims 4 or 5 wherein the mouth-piece incorporates two blowing openings which are immediately adjacent one another and are connected to the pressure transducer whose output is supplied to an input of the evaluation circuit.