Apparatus provided with a capacitive detection and electric line(s) in the capacitive detection zone

Abstract

An appliance includes: at least one measurement electrode, for detecting at least one object in a detection zone, by detecting a signal with respect to a coupling capacitance between the object and said the at least one measurement electrode; at least one capacitive detection electronics, connected to the at least one measurement electrode, and an electric line, having at least one electric wire, in the detection zone;
the appliance also including a signal conditioner, applying to at least a portion of the electric line, an alternating electrical potential (V.sub.G), called guard potential, identical to the detection potential at the detection frequency. The appliance can be a robot, in particular a robotized arm, equipped with an electric line providing a power supply to a component part of the robot.

Claims

1. An appliance comprising: at least one electrode, called measurement electrode, polarized at an alternating electrical potential (VG), called detection electrical potential, different from a ground potential, at a frequency, called detection frequency, in order to detect at least one object in a detection zone; at least one capacitive detection electronics, connected to said at least one measurement electrode, in order to detect a signal with respect to a coupling capacitance between said object and said measurement electrode; and an electric line comprising at least one electric wire, in said detection zone; said appliance also comprising a signal conditioner, applying, to at least a portion of said electric line, an alternating electrical potential (VG), called guard potential, identical to said detection potential at said detection frequency; said electric line being located in said detection zone on a side of said measurement electrodes opposite to at least one guard electrode.

2. The appliance according to claim 1, characterized in that the electric line comprises at least one shielding layer around at least one electric wire on at least a portion of said electric line, the signal conditioner applying the guard potential (VG) to said shielding layer.

3. The appliance according to claim 2, characterized in that the shielding layer is provided in a cable comprising the at least one electric wire.

4. The appliance according to claim 3, characterized in that the shielding layer is in the form of braided wires forming a shielding braid.

5. The appliance according to claim 3, characterized in that the shielding layer is in the form of a continuous conductive layer.

6. The appliance according to claim 2, characterized in that the shielding layer is provided in, or is formed by, a cable sleeve independent of the at least one electric wire, and through which is passed the at least one electric wire.

7. The appliance according to claim 2, characterized in that the signal conditioner comprises a transformer inducing the guard potential (VG) on said shielding layer, by mutual inductance.

8. The appliance according to claim 2, characterized in that the signal conditioner comprises at least one electrical contact with the shielding layer in order to polarize said shielding layer at the guard potential (VG).

9. The appliance according to claim 1, characterized in that the signal conditioner applies the guard potential (VG) to at least one, in particular each, electric wire of the electric line.

10. The appliance according to claim 9, characterized in that the electric line comprises concentric electric wires, and the signal conditioner applies the guard potential (VG) to the outer wire only.

11. The appliance according to claim 9, characterized in that the signal conditioner comprises, for at least one, in particular each, electric wire, a transformer inducing the guard potential on said electric wire by mutual inductance.

12. The appliance according to claim 1, wherein said at least one guard electrode is polarized at the guard potential (VG), and arranged on the side opposite the detection zone with respect to the at least one measurement electrode.

13. The appliance according to claim 1, characterized in that the electric line comprises at least one capacitive measurement electrode polarized at the detection potential, arranged on the outside with respect to the portion of said electric line polarized at the guard potential (VG), and isolated from said portion polarized at the guard potential.

14. The appliance according to claim 1, characterized in that the electric line is an electric power supply line for, and/or for communication with, an electric component part of said appliance.

15. The appliance according to claim 1, characterized in that it is a robot in one of the following forms: robotized arm, mobile robot, vehicle on wheels or tracks, robot of the humanoid, or gynoid, or android type.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

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

(2) FIG. 1 is a diagrammatic representation of a non-limitative embodiment of capacitive detection electronics that can be utilized in the device according to the invention;

(3) FIG. 2 is a partial diagrammatic representation of a non-limitative embodiment of an appliance according to the invention;

(4) FIGS. 3-5 are diagrammatic representations of embodiments for setting an electric line at the guard potential in an appliance according to the invention; and

(5) FIG. 6 is a diagrammatic representation of a non-limitative embodiment of a robot according to the invention.

DETAILED DESCRIPTION

(6) 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.

(7) 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.

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

(9) FIG. 1 is a diagrammatic representation of a non-limitative embodiment of capacitive detection electronics that can be utilized in the device according to the invention.

(10) The detection electronics 100, shown in FIG. 1, can be produced in an analogue or digital form, or an analogue/digital combination.

(11) The detection electronics 100 comprises an oscillator 102 delivering an alternating voltage, denoted V.sub.G, and referenced to a ground potential 104.

(12) The voltage V.sub.G is used as guard potential in order to polarize one or more guard electrodes 106 via a line or several lines, and as excitation or detection potential in order to polarize measurement electrodes 108.sub.1-108.sub.n, which may also be denoted by the reference 108, or the reference 108.sub.i, hereinafter. It thus comprises at least one spectral component at the detection frequency used by the capacitive detection electronics.

(13) The detection electronics 100 comprises a current, or charge, amplifier 110 represented by an operational amplifier (OA) 112 and a feedback capacitor 114 looping the output of the OA 112 at the inverting “−” input of the OA 112.

(14) In addition, in the example shown, the non-inverting “+” input of the OA 112 receives the voltage V.sub.G and the “−” inverting input of the OA 112 is provided in order to be connected to each measurement electrode 108.sub.i via a polling means 116, which can be for example a switch, so as to poll the measurement electrodes 108 individually in turn.

(15) Use of the polling means 116 is of course optional.

(16) Under these conditions, the charge amplifier 110, and in particular the OA 112, supplies at the output a voltage V.sub.s at the frequency of detection and amplitude proportional to the coupling capacitance C.sub.eo, called electrode-object capacitance, between one or more measurement electrodes 108 connected at the “−” input thereof and an object in proximity, or in contact, with said measurement electrode 108.

(17) The detection electronics 100 can also comprise a signal conditioner 118 making it possible to obtain a signal representative of the sought coupling capacitance C.sub.eo. This signal conditioner 118 can comprise for example a synchronous demodulator for demodulating the signal with respect to a carrier, at the detection frequency. The signal conditioner 118 can also comprise an asynchronous demodulator or an amplitude detector. This signal conditioner 118 can of course be produced in an analogue and/or digital form (microprocessor), and comprise all necessary means for filtering, conversion, processing, etc.

(18) The signal conditioner 118 measures and supplies the value of the voltage V.sub.s.

(19) The detection electronics 100 can also comprise a calculation module 120 arranged in order to determine a distance or an item of distance information, and/or a contact or an item of contact information, between at least one measurement electrode 108 and the object, as a function of the signal with respect to the coupling capacitance C.sub.eo originating from the signal conditioner 118.

(20) This calculation module 120 can for example comprise or be produced in the form of a microcontroller, or an FPGA.

(21) The calculation module 120 can also supply other items of information, such as triggering of alarms or safety procedures, when for example the measured distances are less than predetermined distance thresholds.

(22) Of course, the detection electronics 100 can comprise components other than those described.

(23) The detection electronics 100, or at least its sensitive part with the charge amplifier 110, can be referenced (or supplied by electrical power supplies referenced) to the guard potential V.sub.G, in order to minimize the parasitic capacitances.

(24) The detection electronics 100 can also be referenced, more conventionally, to the ground potential 104.

(25) Thus, when an object 122 enters the detection zone 124 of the measurement electrode or electrodes 108.sub.1-108.sub.n, this object 122 enters into capacitive coupling with at least one measurement electrode 108, which modifies the capacitance seen by this measurement electrode 108, and therefore the amplitude of the voltage V.sub.s measured by the measurement electronics 100 connected to this measurement electrode 108.

(26) FIG. 2 is a partial diagrammatic representation of a non-limitative embodiment of an appliance according to the invention.

(27) The appliance 200, shown in FIG. 2, comprises the measurement electrodes 108.sub.1-108.sub.n, the guard electrode or electrodes 106, as well as the detection electronics 100. The measurement electrodes 108.sub.1-108.sub.n, respectively the guard electrode or electrodes 106, can be arranged, for example, on/in an outer wall of the appliance 200. In particular, the electrodes 106-108 can be arranged, for example, on/in a rigid or flexible case of the appliance 200, or in a layer, or a skin, mounted on a portion of the appliance 200.

(28) The appliance 200 can also comprise an electric line 202 located in the detection zone 124 of the measurement electrodes 108.sub.1-108.sub.n, on the side opposite to the at least one guard electrode 106. This electric line 202 can comprise one or more electric wires, or electric cables, used in order to convey an electrical signal for an electric power supply of, or for communication with, a component part of the appliance 200.

(29) The appliance 200 also comprises a signal conditioner 204, applying the guard potential V.sub.G to at least a portion of said electric line 202. Thus, the electric line 202 is not seen by the measurement electrodes 108.sub.1-108.sub.n and does not interfere with the capacitive detection carried out by these measurement electrodes 108.sub.1-108.sub.n.

(30) FIG. 3 is a diagrammatic representation of a first embodiment of setting an electric line at the guard potential in an appliance according to the invention.

(31) In the example shown in FIG. 3, the line 202 comprises one or more electric wires 302 used for conveying electrical signals, for example in order to supply an electrical component part or in order to communicate with an electrical or electronic component part.

(32) The electric line 202 comprises a shielding layer 304, arranged around the electric wires 302. The shielding layer 304 can be produced by braided electric wires, or by a thin layer of an electrically conductive material such as copper or aluminium for example.

(33) The conductive shielding layer 304 is separated from each of the electric wires by an insulator 306. It is itself covered with an insulating layer 308 in order to avoid all electrical contact with the environment, except in the signal conditioner.

(34) In the example shown in FIG. 3, the electrical wires 302 and the shielding layer 304, the insulators 306-308 form part of one and the same cable 310 in the form of a single-piece unit. In other words, the shielding layer 304 is one of the constituent parts of the cable 310 and cannot be separated from the wires 302 without damaging the cable 310.

(35) The signal conditioner 204 comprises a line, or an interface, 312 connected by an electrical connection to the shielding layer 304. This line 312 takes the voltage V.sub.G received by the signal conditioner 204 to the shielding layer 304, so that said shielding layer 304 is polarized at said guard potential V.sub.G.

(36) Thus, the electric wires 302, surrounded by the shielding layer 304, are guarded at the guard potential V.sub.G and cannot be seen by the measurement electrodes 108.sub.1-108.sub.n.

(37) In the example shown, the shielding layer 304 is present on the electric line 202 only on one side of the signal conditioner 204, at the output of this signal conditioner. It can of course also be present on the electric line 202 on the other side of the signal conditioner, at the input. In this case, it can be: either also connected to the guard potential V.sub.G; or connected to another potential such as ground, or electrically floating, in which case it is interrupted electrically at the level of the signal conditioner 204 between the input and the output.

(38) Optionally, the electric line 202 can comprise one or more measurement electrodes arranged on the outer surface of the cable 310 and connected to capacitive detection electronics.

(39) FIG. 4 is a diagrammatic representation of a second embodiment of setting an electric line at the guard potential in an appliance according to the invention.

(40) In the example shown in FIG. 4, the line 202 comprises the electric wires 302 used for conveying electrical signals, for example in order to supply an electrical component part or in order to communicate with an electrical or electronic component part.

(41) The electric line 202 comprises an electrically conductive shielding layer 402, included within a cable sleeve sheath arranged around the electric wires 302. The shielding layer 402 can be produced in particular by the metallic wall of a corrugated metallic cable sleeve sheath, produced with a spiral metallic strip, or by a shielding layer of the cable sleeve sheath, with braided electric wires, or a thin layer of an electrically conductive material such as copper or aluminium for example.

(42) The conductive shielding layer 402 can be covered with an electrically insulating layer 404 in order to avoid all electrical contact with the environment, except in the signal conditioner.

(43) In the example shown in FIG. 4, the shielding layer 402 is part of, or forms, a cable sleeve 406. In other words, the shielding layer 402 is independent of the wires 302, and can be produced and installed independently of the wires 302. In addition, at least one wire 302 can be removed, respectively added, without the need to modify the electric line 202, or the cable sleeve 406.

(44) The signal conditioner 204 comprises the line, or the interface, 312 taking the voltage V.sub.G received by the signal conditioner 204 to the shielding layer 402, so that said shielding layer 402 is polarized at said guard potential V.sub.G.

(45) Thus, the electric wires 302, surrounded by the shielding layer 402, are guarded at the guard potential V.sub.G and cannot be seen by the measurement electrodes 108.sub.1-108.sub.n.

(46) In the example shown, the shielding layer 402 is present on the electric line 202 only on one side of the signal conditioner 204, at the output of this signal conditioner. It can of course also be present on the electric line 202 on the other side of the signal conditioner, at the input. In this case, it can be: either also connected to the guard potential V.sub.G; or connected to another potential such as ground, or electrically floating, in which case it is interrupted electrically at the level of the signal conditioner 204 between the input and the output.

(47) Optionally, the electric line 202 can comprise one or more measurement electrodes arranged on an outer surface of the cable sleeve 406 and connected to capacitive detection electronics.

(48) FIG. 5 is a diagrammatic representation of a third embodiment of setting an electric line at the guard potential in an appliance according to the invention.

(49) In the example shown in FIG. 5, the line 202 comprises the electric wires 302 used for conveying electrical signals, for example in order to supply an electrical component part or in order to communicate with an electrical or electronic component part.

(50) In the example shown in FIG. 5, the signal conditioner 204 comprises: a primary inductance 502 supplied with power by the potential V.sub.G or by a potential proportional to V.sub.G; and for each electric wire 302, a secondary inductance 504 in series with said electric line 302.

(51) Each of the inductances 502-504 can be formed by a coil for example.

(52) The primary inductance 502 is in inductive coupling with each of the secondary inductances 504, so as to generate the potential V.sub.G by inductive coupling at the level of each of the secondary inductances 504. The potential V.sub.G generated at the level of each secondary inductance 504 is thus added, or superposed, on the electrical signal conveyed by the electric line 302 to which said secondary inductance 504 is connected. More precisely, a voltage source V.sub.G, or a Thévenin generator, is thus inserted in series on all the electric lines 302.

(53) Thus, each electric line 302 at the output of the signal conditioner 204 is polarized (with respect to ground) at the guard potential V.sub.G and is thus not seen by the measurement electrodes 108.sub.1-108.sub.n.

(54) It should be noted that the signals conveyed by the electric lines 302 in addition to the guard potential V.sub.G do not interfere with the capacitive measurement provided that they have no component (or at least no detectable component) at the measurement frequency.

(55) Furthermore, the potential of the electric lines 302 is not affected at the input of the signal conditioner, therefore the signal conditioner 204 has no influence on the electronics located upstream of this signal conditioner.

(56) This embodiment requires that the sum of the currents in the electric lines 302 is zero. This condition is fulfilled provided that the ground or the reference potential of the electronics downstream of the signal conditioner is also transmitted by an electric line 302, which is generally the case in practice for reasons of electrical protection of the tools.

(57) Moreover, in this case, the signal conditioner 204 has no influence on the electronics, which are located downstream of this signal conditioner, since the potential differences between the electric lines 302 are all preserved.

(58) Preferably, the primary inductance 502 and the secondary inductances 504 are wound on a common ferromagnetic core 506, so as to optimize the couplings by mutual inductance. The assembly thus forms a transformer. The potential applied to the primary inductance 502 is chosen so as to generate potentials V.sub.G in the secondary inductances 504, taking account of the actual inductive couplings.

(59) The electric line 202 in FIG. 5 does not comprise anything more than the electric wires 302. Optionally, according to alternatives (not shown), the electric line 202 can comprise: the insulation layer 404, for example in the case where the electric line 202 comprises, or is formed by, a cable sleeve through which the electric wires 302 are passed; the insulation layer 306 and/or the insulation layer 308, for example in the case where the electric line 202 comprises, or is formed by, an electric cable comprising the electric wires 302.

(60) Furthermore, the signal conditioner 204 in FIG. 5 can be used in each of the examples described with reference to FIGS. 3 and 4.

(61) According to yet another alternative, when the electric line comprises concentric electric conductors/wires, it is sufficient to polarize only the outer electric wire at the guard potential. In this case, the signal conditioner can comprise a secondary inductance for the outer wire only.

(62) FIG. 6 is a diagrammatic representation of a non-limitative embodiment of a robot according to the invention.

(63) The robot 600, shown in FIG. 6, is a robotized arm such as an industrial collaborative robot working under the supervision of, or in collaboration with, an operator, or also a medical robot in the case of a surgical operation on the body of a person, or also a personal assistance robot.

(64) The robotized arm 600 comprises a fixed segment 602, three articulated segments 604-608 and a functional head 610 fixed to the segment 608. The functional head 610 is a gripper equipped with an electric motor (not shown).

(65) Each segment 602-608 is equipped with measurement electrodes 108 in order to carry out a capacitive detection of objects located in the environment of the robotized arm 600, in particular placed in/on the outer case of said segment.

(66) The robotized arm 600 comprises a line 202 in order to supply power to the functional head and/or in order to communicate with the functional head and a signal conditioner 204 in order to apply a guard potential to the line 202 according to any one of the examples described with reference to FIGS. 3-5.

(67) The signal conditioner 204 can be independent of the robotized arm 600.

(68) Alternatively, the signal conditioner 204 can be integrated in the robotized arm 600, or in electronics of the robotized arm.

(69) Alternatively, the signal conditioner 204 can be integrated in capacitive detection electronics equipping the robotized arm 600.

(70) 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.