Robot equipped with capacitive detection means and walls referenced to a guard potential

Abstract

A robot including: for at least one sub-part, at least one measurement electrode, at least one type of electrical polarization for polarizing the at least one measurement electrode at a first alternating electrical potential, and the at least one polarization type is also arranged in order to polarize at least one electrically conductive part of the outer wall of at least one sub-part, at an alternating electrical potential (V.sub.G), called guard potential, identical or substantially identical to the first potential, at a working frequency.

Claims

1. A robot comprising: at least one sub-part, called equipped sub-part, at least one capacitive detection electrode, called measurement electrode, placed on, or in, an outer wall of said equipped sub-part; at least one means of electrical polarization for polarizing said at least one measurement electrode at a first alternating electrical potential, which is different from a general ground potential (MG), at a frequency, called working frequency; and at least one electronic unit, called detection unit, for measuring a signal relative to a coupling capacitance, called electrode-object capacitance, between the at least one measurement electrode and a nearby object, wherein said at least one polarization means is also arranged to polarize at least one electrically conductive part of the outer wall of said equipped sub-part, at an alternating electrical potential (V.sub.G), called guard potential, which is identical or substantially identical to said first alternating electrical potential, at said working frequency.

2. The robot according to claim 1, wherein said equipped sub-part of said robot is: a segment of said robot, or a mechanical interface, which is articulated or non-articulated, between at least two segments of said robot, or a functional head, which is articulated or non-articulated, forming a tool, or a tool head.

3. The robot according to claim 1, further comprising another sub-part, called non-equipped sub-part, not comprising a measurement electrode, at least one electrically conductive part of the outer wall is polarized at the guard potential (V.sub.G).

4. The robot according to claim 1, wherein the outer wall is not polarized at the guard potential (V.sub.G).

5. The robot according to claim 1, further comprising another sub-part called fitted-out sub-part, comprising at least one electrical item (Mo) placed in said fitted out sub-part.

6. The robot according to claim 5, wherein the fitted-out sub-part comprises, for at least one item, a volume or walls, called guard volume or guard walls, placed around said at least one item and polarized at the guard potential (V.sub.G).

7. The robot according to claim 5, wherein the fitted-out sub-part comprises at least one item electrically polarized at, or referenced to, the guard potential (V.sub.G).

8. The robot according to claim 1, further comprising a functional head formed forming a capacitive detection electrode, the at least one electrical polarization means also being arranged to polarize said functional head at the first alternating electrical potential, and the at least one electronic detection unit being arranged to measure a signal relating to a coupling capacitance between said functional head and a nearby object.

9. The robot according to claim 8, further comprising at least one electrical item (Mo) arranged in the functional head, and for at least one item, a volume or walls, called guard volume or guard walls, placed around said at least one item and polarized at the guard potential (V.sub.G).

10. The robot according to claim 7, further comprising, for at least one electrical item (Mo) that is electrically polarized at, or referenced to, the guard potential (V.sub.G), at least one electrical converter arranged to: receive at least one electrical signal, called input signal, such as a supply input signal or a control input signal, intended for said at least one electrical element (Mo), and reference said input signal to the guard potential (V.sub.G); and/or receive at least one electrical signal, called output signal, transmitted by said at least one electrical item (Mo), and reference said output signal to the electrical ground potential (MG) of a controller for which it is intended.

11. The robot according to claim 10, wherein the electrical converter comprises: at least one supply with galvanic isolation, such as a DC/DC converter, for generating the input signal for said at least one electrical item (Mo); at least one electrical interface without galvanic contact, of the capacitive type or by opto-coupler, for the input signal, or the output signal; one or more high-impedance inductors for receiving and transmitting the input signal or the output signal; and/or at least one capacitor-commutated charge-transfer or charge-pump converter.

12. The robot according to claim 1, wherein the outer wall of each sub-part of said robot is polarized at the guard potential, and further comprises an interface for fastening said robot to an external support, and an electrical insulator at said fastening interface.

13. The robot according to claim 1, wherein for said equipped sub-part, the outer wall is produced, at least partially: from an electrically conductive material, or from an electrically non-conductive material comprising an electrically conductive layer.

14. The robot according to claim 1, wherein the robot is presented in one of the following forms: robotized arm, mobile robot or android.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other advantages and characteristics will become apparent on reading the detailed description of non-limitative examples and from the attached drawings in which:

(2) FIG. 1 is a diagrammatic representation of an example robot of the prior art equipped with capacitive detection electrodes;

(3) FIGS. 2-5 are diagrammatic representations of different embodiments of a robot according to the invention;

(4) FIGS. 6-11 are partial diagrammatic representations of different examples of a functional head with which a robot according to the invention can be equipped;

(5) FIG. 12 is a diagrammatic representation of an embodiment of an electronic detection unit that can be utilized in a robot according to the invention;

(6) FIG. 13 is a diagrammatic representation of an articulation that can be utilized in a robot according to the invention; and

(7) FIG. 14 is a diagrammatic representation of a segment that can be utilized in a robot according to the invention.

DETAILED DESCRIPTION

(8) It is well understood that the embodiments that will be described hereinafter are in no way limitative. In particular, variants of the invention may be envisaged comprising only a selection of characteristics described hereinafter, in isolation from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention with respect to the state of the prior art. This selection comprises at least one, preferably functional, characteristic without structural details, or with only a part of the structural details if this part alone is sufficient to confer a technical advantage or to differentiate the invention with respect to the state of the prior art.

(9) In particular, all the variants and all the embodiments described may be combined together if there is no objection to such combination from a technical point of view.

(10) In the figures, elements that are common to several figures retain the same reference.

(11) FIG. 1 is a diagrammatic representation of an embodiment of a robot according to the prior art equipped with capacitive detection electrodes.

(12) The robotized arm 100 can be, for example, an industrial collaborative robot working under the supervision of, or in collaboration with, an operator OP, or also a medical robot in the case of a surgical operation on the body of a person, or also a personal assistance robot.

(13) The robot 100, shown in FIG. 1, is presented in the form of an articulated robotized arm comprising eight sub-parts 102-116, namely: four segments 102, 104, 106 and 108; a functional head 110; and three mechanical interfaces 112, 114 and 116.

(14) Segment 102 is the base segment fastened to a support S, which can be the ground. The segment 108 is the segment located on the side of a free end of the robot 100. Each segment 102-108 is delimited by an outer wall, respectively 102.sub.1-108.sub.1, produced by the surface of an element of the structure of the segment, or by one or more cover elements, for example made from plastic material (polymer) or metal(s). Generally, each segment 102-108 is hollow and enables electrical or electronic items to be placed in said segment.

(15) The functional head 110 is located on the side of the segment 108, and forms a tool or a tool-holder, which in the example shown is a gripper.

(16) Segments 102-108 are articulated by means of the articulated mechanical interfaces 112-116, also called articulations hereinafter. Articulation 112 is located between segments 102 and 104, articulation 114 is located between segments 104 and 106, and articulation 116 is located between segments 106 and 108. Each segment 112-116 comprises a wall or outer wall, respectively 112.sub.1-116.sub.1, produced from one or more cover elements, for example made from plastic material (polymer) or metal(s).

(17) Each of the articulations 112-116 is an articulation rotating about an axis. Alternatively, at least one articulation 112-116 can, additionally or instead, be a translational articulation, and/or a rotational articulation with several axes.

(18) The articulated segments 106 and 108 are equipped with one or more capacitive detection electrodes 118, called measurement electrodes. Each measurement electrode 118 with which the segment 106, respectively the segment 108, is equipped, is electrically isolated from the outer wall 106.sub.1, respectively 108.sub.1, of this segment.

(19) An electronic module 120 is associated with the robot 100. This electronic module 120 comprises: an electronic polarization unit polarizing each measurement electrode 118 at a first alternating potential, different from a general ground potential (MG), at a non-zero working frequency; and an electronic measurement unit for measuring an electrical signal, in particular an electric current, for each of the measurement electrodes 118 in order to deduce therefrom a capacitance, called electrode-object capacitance, resulting from a capacitive coupling between the measurement electrode and an object in its vicinity electrically polarized at the ground potential (MG) or at least at a potential different from the first alternating potential, and representative of a distance between said measurement electrode 118 and a nearby object.

(20) Each measurement electrode 118 is also preferably guarded by an electrode, called guard electrode (not shown) polarized by an alternating guard potential, denoted V.sub.G, identical or substantially identical to the first potential at the working frequency, and placed between the wall of the segment and the measurement electrode 118.

(21) Thus, the robot 100 can detect an object located in its environment by means of the measurement electrodes 118.

(22) However, in certain configurations, the measurement electrodes 118 also detect the segments 102-108 themselves, or the functional head 110. For example, when one of the equipped segments 106 or 108 come close to the segment 102 or the segment 104 or also the functional head 110, then the measurement electrodes 118 equipping this segment detect it as being a nearby object, when this is not the case. The measurement electrodes 118 of one of the equipped segments 106-108 can thus detect the other one of the equipped segments 106-108 as being a nearby object, for example when the other segment is equipped with a small number of measurement electrodes 108.

(23) These self-detections reduce the operational range of the robot 100 and detract from its functionality.

(24) The invention makes it possible to overcome this drawback.

(25) FIG. 2 is a diagrammatic representation of a non-limitative embodiment of the robot according to the invention.

(26) The robot 200, shown in FIG. 2, comprises all the elements of the robot 100 in FIG. 1.

(27) In addition to what is described for the robot 100 in FIG. 1, in the robot 200 in FIG. 2, the base segment 102 is electrically isolated from the support S by an insulating gasket 202.

(28) In addition, the outer walls 102.sub.1 and 104.sub.1 of the segments 102 and 104 are made from an electrically conductive material and polarized at a guard potential, denoted V.sub.G, identical or substantially identical to the first potential at the working frequency.

(29) Thus, the outer walls 102.sub.1 and 104.sub.1 of the segments 102 and 104, not equipped with measurement electrodes, are set at the guard potential V.sub.G. As this guard potential V.sub.G is identical to the first potential at the working frequency, the non-equipped segments 102 and 104 are electrically invisible to the measurement electrodes 118 with which the segments 106 and 108 are equipped, as they do not generate coupling capacitances with these electrodes. In this configuration, there is therefore no risk of the measurement electrodes 118 detecting the segments 102 and 104.

(30) FIG. 3 is a diagrammatic representation of another non-limitative embodiment of a robot according to the invention.

(31) The robot 300, shown in FIG. 3, comprises all the elements of the robot 200 in FIG. 2.

(32) In addition to what is described for the robot 200 in FIG. 2, in the robot 300 in FIG. 3, the outer walls 106.sub.1 and 108.sub.1 of the segments 106 and 108 are also made from electrically conductive material and polarized at the guard potential V.sub.G.

(33) Thus, like the non-equipped segments 102 and 104, the equipped segments 106 and 108 are electrically invisible to the measurement electrodes 118 with which the segments 106 and 108 are equipped. In this configuration, there is therefore no risk of the measurement electrodes 118 detecting the segments 102-108. In this configuration, it is not necessary to insert a guard between the measurement electrodes 118 and the wall of the segments which support them, which simplifies their arrangement.

(34) FIG. 4 is a diagrammatic representation of another non-limitative embodiment of a robot according to the invention.

(35) The robot 400, shown in FIG. 4, comprises all the elements of the robot 300 in FIG. 3.

(36) In addition to what is described for the robot 300 in FIG. 3, in the robot 400 in FIG. 4, the outer walls 112.sub.1, 114.sub.1 and 116.sub.1 of the segments 112-116 are also made from electrically conductive material and polarized at the guard potential V.sub.G.

(37) Thus, like the segments 102-108, the articulations 112-116 are also electrically invisible to the measurement electrodes 118 with which the segments 106 and 108 are equipped. In this configuration, there is therefore no risk of the measurement electrodes 118 detecting the segments 102-108, or the articulations 112-116.

(38) FIG. 5 is a diagrammatic representation of another non-limitative embodiment of a robot according to the invention.

(39) The robot 500, shown in FIG. 5, comprises all the elements of the robot 200 in FIG. 2.

(40) In addition to what is described for the robot 200 in FIG. 2, in the robot 500 in FIG. 3, the outer walls 112.sub.1, 114.sub.1 and 116.sub.1 of the articulations 112-116 are also made from electrically conductive material and polarized at the guard potential V.sub.G.

(41) Thus, like the non-equipped segments 102 and 104, the articulations 112-116 are electrically invisible to the measurement electrodes 118 with which the segments 106 and 108 are equipped. In this configuration, there is therefore no risk of the measurement electrodes 118 detecting the segments 102-104, or the articulations 112-116.

(42) In the examples which have just been described, only the segments 106 and 108 are equipped with measurement electrodes 118.

(43) Of course, in alternative embodiments, at least one, in particular each segment of the robot can be equipped with measurement electrodes.

(44) Alternatively or in addition, the functional head of the robot can also be equipped with measurement electrodes.

(45) Alternatively or in addition, the articulations 112-116 can also be equipped with measurement electrodes.

(46) Examples of a functional head that can be utilized in the robot according to the invention, in particular in combination with any one of the above-described robots 200, 300, 400 and 500 will now be described.

(47) FIG. 6 is a diagrammatic representation of an example of a functional head that can be utilized in a robot according to the invention, in particular in any one of the robots in FIGS. 2-5.

(48) In the example shown in FIG. 6, the outer wall of the segment 108 on which the functional head 110 is fastened, is polarized at the guard potential V.sub.G.

(49) In addition, the functional head, or the outer wall 110.sub.1 of the functional head 110, is also set at the guard potential V.sub.G.

(50) Thus, the functional head 110 is electrically invisible to the measurement electrodes 118 with which the segments 106 and 108 are equipped. In this configuration, there is therefore no risk of the measurement electrodes 118 detecting the functional head.

(51) FIG. 7 is a diagrammatic representation of another example of a functional head that can be utilized in a robot according to the invention, in particular in any one of the robots in FIGS. 2-5.

(52) In the example shown in FIG. 6, the outer wall 108.sub.1 of the segment 108 on which the functional head 110 is fastened, is polarized at the guard potential V.sub.G.

(53) At the same time, the functional head 110, or the outer wall 110.sub.1 of the functional head 110, is polarized at the guard potential V.sub.G. In addition, an electrical insulator 702 is inserted between the segment 108 and the functional head 110 so that the functional head 110 is electrically isolated from the segment 108.

(54) Under these conditions, the functional head 110 is electrically invisible to the measurement electrodes 118 with which the segments 106 and 108 are equipped. In this configuration, there is therefore no risk of the measurement electrodes 118 detecting the functional head.

(55) FIG. 8 is a diagrammatic representation of another example of a functional head that can be utilized in a robot according to the invention, in particular in any one of the robots in FIGS. 2-5.

(56) In the example shown in FIG. 8, the outer wall 108.sub.1 of the segment 108 on which the functional head 110 is fastened, is polarized at the guard potential V.sub.G.

(57) The functional head 110 is electrically isolated from the segment 108 by the electrical insulator 702.

(58) In addition, the functional head 110 is polarized at the first alternating potential, like the measurement electrodes 118, so as to form a capacitive detection electrode. As the wall 108.sub.1 of the segment 108 is at the guard potential V.sub.G, the detection electrode formed by the functional head 110 is electrically guarded by said outer wall 108.sub.1 of the segment 108.

(59) Under these conditions, the functional head 110 is used as a capacitive detection electrode for detecting objects or the person 102 that are present in a detection zone around the functional head 110.

(60) The module 120 makes it possible to measure an electrical signal, in particular an electric current, relating to a coupling capacitance, called electrode-object capacitance, denoted C.sub.eo, between the functional head 110 and its environment.

(61) FIG. 9 is a diagrammatic representation of another example of a functional head that can be utilized in a robot according to the invention, in particular in any one of the robots in FIGS. 2-5.

(62) In the example shown in FIG. 9, the outer wall 108.sub.1 of the segment 108 on which the functional head 110 is fastened, is not polarized at the guard potential V.sub.G.

(63) The functional head 110 is polarized at the first alternating potential, like the measurement electrodes 118.

(64) In addition, a guard element 902, polarized at the guard potential V.sub.G, is placed between the functional head 110 and the segment 108. This guard element 902 makes it possible to electrically guard the functional head 110 used as capacitive detection electrode.

(65) The guard element 902 is electrically isolated from the functional head 110 by the electrical insulator 702 and from the segment 108 by an electrical insulator 904.

(66) Under these conditions, the functional head 110 is used as a capacitive detection electrode guarded by the guard element 902 for detecting objects or the person 102 that are present in a detection zone around the functional head 110.

(67) The guard element 902 can be produced from any electrically conductive element, for example a piece of sheet metal. The guard element 902 can be plane, or can have the form of a sleeve covering a part of the segment 108 or of the functional head 110.

(68) In the examples of FIGS. 8 and 9, the functional head is polarized at the first electrical potential and is used as capacitive detection electrode.

(69) However, in certain configurations, the functional head can comprise an electrical item, such as a motor, a sensor, etc. receiving an input signal and/or transmitting an output signal. In this configuration, such an electrical item interferes with the capacitive detection carried out by the functional head.

(70) Examples will now be described which allow this drawback to be overcome.

(71) FIG. 10 is a diagrammatic representation of another example of a functional head that can be utilized in a robot according to the invention, in particular in any one of the robots in FIGS. 2-5.

(72) In the example shown in FIG. 10, the functional head 110 comprises all the elements of the functional head in FIG. 8.

(73) In addition, the functional head 110 comprises an electrical item, which in the present example is a motor Mo making it possible to move the grippers of the functional head 110.

(74) The electric motor Mo receives a supply signal from, and optionally transmits an output signal making it possible to determine the position of the grippers to, a controller 1002 which can be a robot controller. Generally, these input/output signals are referenced to an electrical ground potential MG. Now, when the functional head 110 is used as capacitive detection electrode, then the motor Mo as well as the electrical lines conducting the input/output signals, referenced to the general ground potential MG, interfere with the detection carried out by the functional head 110.

(75) In order to avoid this interference, the motor Mo, as well as the connectors and electronic unit associated therewith, are placed in a guard volume 1006 polarized at the guard potential V.sub.G. Thus, the electric motor Mo and the connectors and electronic unit associated therewith, are not visible to the functional head 110 and do not interfere with the capacitive detection carried out by said functional head 110.

(76) Of course, such a guard volume can also be used in combination with the embodiment in FIG. 9.

(77) FIG. 11 is a diagrammatic representation of another example of a functional head that can be utilized in a robot according to the invention, in particular in any one of the robots in FIGS. 2-5.

(78) In the example shown in FIG. 11, the functional head 110 comprises all the elements of the functional head in FIG. 10, with the exception of the guard volume 1006.

(79) Instead of the guard volume, a potential converter 1102 is used. This converter 1102 is placed between the controller 1002 and the electric motor Mo. The function of this converter 1102 is to: receive at least one electrical signal, called input signal, such as a supply or control signal, transmitted by the controller 1002 and intended for said electric motor Mo, and reference said input signal to the guard potential (V.sub.G); and receive at least one electrical signal, called output signal, transmitted by said electric motor Mo and intended for the controller 1002, and reference said output signal to the electrical ground potential MG of the controller 1002.

(80) Thus the electric motor Mo, as well as the connectors and the electronic unit associated therewith, are supplied by signals referenced to the guard potential V.sub.G and do not interfere with the detection electrode constituted by the functional head 110.

(81) Of course, such a guard volume can also be used in combination with the embodiment in FIG. 9.

(82) FIG. 12 is a diagrammatic representation of an electronic detection unit that can be utilized in a robot according to the invention, in particular in any one of the robots in FIGS. 2-5.

(83) The electronic module 1200, shown in FIG. 12, can be the electronic module 120 in FIGS. 2-5.

(84) The electronic module 1200 comprises an oscillator 1202 that generates an alternating excitation voltage, denoted V.sub.G, used as guard potential.

(85) The electronic module 1200 also comprises an electronic detection unit 1204 composed of a current or charge amplifier, represented by an operational amplifier 1206 and a counter-reaction capacitor 1208.

(86) The electronic detection unit 1204 also comprises a conditioner 1210 making it possible to obtain a signal representative of the sought coupling capacitance C.sub.eo, and/or of the presence or the proximity of an object, a body. This conditioner 1210 can comprise for example a synchronous demodulator for demodulating the signal with respect to a carrier, at a working frequency. The conditioner 1210 can also comprise an asynchronous demodulator or an amplitude detector. This conditioner 1210 can of course be produced in an analogue and/or digital form (microprocessor), and comprise all necessary means for filtering, conversion, processing etc.

(87) The electronic module 1200 can comprise an electronic detection unit 1204 dedicated to each of the detection electrodes 118 and to the functional head 110.

(88) Alternatively, and as shown in FIG. 12, the electronic module 1200 can comprise a single electronic detection unit 1204 and a polling means 1210 connecting said electronic detection unit 1204 in turn with each measurement electrode 118 and with the functional head 110, so as to poll individually each of said measurement electrodes and the functional head 110.

(89) Of course, the electronic module 1200 can comprise components other than those described.

(90) In addition, the electronic module 1200 can be at least partially incorporated into an electronic unit of the robot, or into the body of the robot, or into the functional head, or also into an existing or additional interface, positioned between the functional head and the body of the robot.

(91) The electronic module 1200 can also be presented in the form of a module or a housing external to the body of the robot. In this case, all or part of the electrical connections described can be located in the electronic module 1200, connected to the other elements with cables.

(92) In the examples that have just been described, it is the casings/outer walls of a part or all of the sub-parts of the robot, namely the casings/outer walls of the segments 102-108 and/or of the functional head 110 and/or of the articulations 112-116, which are set at the guard potential V.sub.G. This requires the casings/outer walls of these sub-parts to be at least partially electrically conductive.

(93) However, it may be the case that a sub-part of the robot, such as for example an articulation, a segment or the functional head, comprises a casing/outer wall that is not electrically conductive.

(94) When such a sub-part is equipped, i.e. it comprises at least one electrical item, then the latter may interfere with the capacitive detection if it is referenced to an electrical potential different from the first potential or from the guard potential.

(95) In order to avoid such interference, the electrical item of a sub-part can be placed in a guard volume, as described in FIG. 10 for the functional head.

(96) Alternatively or in addition, a potential converter can be used, as described in FIG. 11 for the functional head, in order to convert the electrical reference of the input/output signals to/from the item of the sub-part.

(97) FIG. 13 is a diagrammatic representation of an articulation that can be utilized in a robot according to the invention.

(98) In particular, the articulation 1302 shown in FIG. 13 can be any one of the articulations 112-116 of the robot 100 and can be utilized in any one of the robots in FIGS. 1-11.

(99) In the example shown, the casing/outer wall 1302.sub.1 of the articulation 1302 is not conductive, and cannot therefore be set at the guard potential V.sub.G.

(100) At the same time, the articulation 1302 comprises an electrical item, which in the present example is a motor 1304. In order to ensure that the motor 1304 placed in the articulation 1302 does not interfere with the capacitive detection in the robot, a potential converter, such as for example the converter 1102, is used. The function of this converter 1102 is to: receive at least one electrical signal, called input signal, such as a supply or control signal, transmitted for example by the controller 1002 and intended for said motor 1304, and reference said input signal to the guard potential (V.sub.G), and receive at least one electrical signal, called output signal, transmitted by said motor 1304 and intended for the controller 1002, and reference said output signal to the electrical ground potential MG of the controller 1002.

(101) Thus the motor 1304, located in the articulation as well as the connectors and the electronic unit associated therewith, are supplied by signals referenced to the guard potential V.sub.G and do not interfere with the capacitive detection.

(102) Alternatively, the converter can be replaced by a guard volume, such as described with reference to FIG. 10.

(103) FIG. 14 is a diagrammatic representation of a segment that can be utilized in a robot according to the invention.

(104) In particular, the segment 1402 shown in FIG. 14 can be any one of the segments 102-108 of the robot 100.

(105) In the example shown, the outer casing 1402.sub.1 is not conductive, and cannot therefore be set at the guard potential V.sub.G.

(106) At the same time, the segment 1402 comprises an electrical item, which in the present example is an electrical module 1404. In order to ensure that the electrical module 1404 does not interfere with the capacitive detection in the robot, a potential converter, such as for example the converter 1102, is used. The function of this converter is to: receive at least one electrical signal, called input signal, such as a supply or control signal, transmitted for example by the controller 1002 and intended for the module 1404, and reference said input signal to the guard potential (V.sub.G); and receive at least one electrical signal, called output signal, transmitted by the module 1404 and intended for the controller 1002, and reference said output signal to the electrical ground potential MG of the controller 1002.

(107) Thus the module, located in the articulation as well as the connectors and the electronic unit associated therewith, are supplied by signals referenced to the guard potential V.sub.G and do not interfere with the capacitive detection.

(108) Alternatively, the converter can be replaced by a guard volume, such as described with reference to FIG. 10.

(109) The converter used can be common to all the items with which the robot is equipped. Alternatively, a converter can be dedicated to an item, or a group of items.

(110) Of course, an electrical item of a sub-part, such as a segment or an articulation, can be placed in a guard volume, or referenced to a guard potential by a potential converter as described in relation to FIG. 13 or FIG. 14, even if the casing or the outer wall of the sub-part is partially or totally electrically conductive, and in particular even if it is polarized at the guard potential V.sub.G.

(111) In this case, all of the sub-part can be referenced to the guard potential V.sub.G.

(112) A sub-part such as an articulation or a segment can of course comprise measurement electrodes 118 placed on a part of the non-conductive casing/outer wall.

(113) According to whether or not it comprises conductive internal elements or electrical items polarized at or referenced to the guard potential V.sub.G, it may be preferable to insert a guard plane vis--vis the face of the electrodes directed towards the inside of the sub-part, in order to ensure that the measurement electrodes are only sensitive to the presence of objects close to their outer face. This guard plane can be placed for example between the measurement electrodes

(114) and the outer wall, or on the inner face of the wall of the sub-part.

(115) Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without exceeding the scope of the invention.