WO2019228976A1

WO2019228976A1 - Communication device, capacitive detection device and apparatus provided with such a detection device

Info

Publication number: WO2019228976A1
Application number: PCT/EP2019/063645
Authority: WO
Inventors: Stéphane ROYET; Christian Neel; Alain Courteville
Original assignee: Fogale Nanotech
Priority date: 2018-05-30
Filing date: 2019-05-27
Publication date: 2019-12-05
Also published as: FR3082075A1

Abstract

The invention relates to a communication device (200) for implementing with a differential-mode communication bus, comprising at least two differential lines (102, 104) for conveying a first differential-mode signal (110) between at least two differential communication modules (1061,1062), characterised in that it also comprises: at least one common-mode emitter (202), for injecting the same second so-called common-mode signal (210), in an alternating manner, into each of said at least two differential lines (102, 104), at a point of said communication bus; and at least one common-mode receiver (206) for receiving said second signal (210) at another point of said communication bus.

Description

"Communication device, capacitive detection device and equipment provided with such a detection device"

Technical area

The present invention relates to a signal communication device using a communication bus in differential mode. It also relates to a capacitive detection device provided with such a communication device, and a device provided with such a capacitive detection device.

The field of the invention is, in a nonlimiting manner, that of communication buses in differential mode, in particular for capacitive detection devices, and more particularly in the field of robotics.

State of the art

Industrial or domestic robots, in particular cobots, generally comprise a body on which is fixed a functional head, in the form of a tool or a tool holder, allowing them to perform one or more tasks in an environment. These robots are generally equipped with a communication bus in differential mode allowing the various organs of the robot to communicate with each other.

To be able to use a robot in an environment comprising humans and / or objects, said robot may be equipped with capacitive detection units for detecting said humans / objects.

In known manner, each capacitive detection unit comprises measurement electrodes, possibly guard electrodes, biased to an alternating excitation potential and an electronic detection. The electrodes of a detection unit may be integrated into a covering element, or shell, replacing or, in addition, an existing cladding element of the robot.

To avoid the parasitic coupling capacitors between the different detection units equipping a robot, it is necessary that the electrodes of these units are polarized at the same excitation potential. This requirement requires lines of signal transmission between the different capacitive detection units, which makes the integration of these units on robots, especially existing robot arms, time consuming, expensive and cumbersome.

In general, the problem described above arises in any equipment implementing several functional units to be powered by the same power supply signal, or synchronization.

An object of the present invention is to overcome the aforementioned drawbacks.

Another object of the present invention is to propose a signal communication device allowing a simpler, less costly and less time-consuming integration of functional units, in particular of capacitive detection units, in a device, and in particular in a device. robot such as a robotic arm.

Presentation of the invention

At least one of these objects is achieved with a communication device intended to be implemented with a differential mode communication bus comprising at least two differential lines for conveying a first differential mode signal between at least two differential communication modules, characterized in that it further comprises:

at least one common-mode transmitter, for injecting the same second signal, called common-mode, alternating, on each of said at least two differential lines, at a point of said communication bus; and

at least one receiver in common mode, for receiving said second signal, at another point of said communication bus.

Thus, the communication device according to the invention makes it possible to use a communication bus in differential mode, existing within an equipment such as a robot, for conveying, in common mode, a synchronization or excitation signal. to a plurality of functional units within said equipment. Consequently, when several functional units need to be synchronized or fed by the same excitation signal, such as capacitive detection units, the communication device according to the invention makes it possible to integrate these functional units with the within said equipment without drawing additional transmission lines dedicated to the excitation or synchronization of these functional units: this makes the integration of these units simpler, less expensive and less time-consuming.

Similarly, the communication device according to the invention makes it possible to use a communication bus in differential mode, existing within an equipment such as a robot, for conveying, in common mode, an additional digital communication signal or analog, to, or from, or between, a plurality of functional units within said equipment.

In the present description, to avoid redaction, the term "mass potential" refers to a reference potential of the electronics, which can be for example an electrical mass or a ground potential. This ground potential can correspond to an earth potential, or to another potential connected or not to the earth potential.

In the present application, two alternative potentials are identical at a given frequency when they each comprise an alternating component identical to this frequency. Thus, at least one of the two potentials identical to said frequency may further comprise a DC component, and / or an AC component with a frequency different from said given frequency.

Similarly, two alternative potentials are different at the working frequency when they have no alternative component identical to this working frequency.

The second alternating signal may preferably be a sinusoidal signal.

Alternatively, the second alternating signal may be a square, triangular signal, or any other waveform. It can also be a communication signal with coded information in digital or analog form. According to embodiments, at least one common mode transmitter, and / or at least one common mode receiver, may comprise a block, called differential mode isolation, with a connection to each differential line and a connection, called common mode, having an impedance for the common mode signal, between the connections to the differential lines and the common mode connection, less than an impedance for the differential mode signal, between said connections to the differential lines.

The impedance for the common mode signal can be defined as the ratio, or the modulus of the ratio, between the common mode voltage (or the average instantaneous voltage) between the differential lines and the common mode connection, and the total current or the sum of the currents flowing between the differential lines and the common mode connection.

The impedance for the differential mode signal can be defined as the ratio, or the modulus of the ratio, between the voltage between the differential lines, and the current flowing between the differential lines via the differential mode isolation block.

According to embodiments:

the impedance for the common mode signal may be equal to or less than half, or one-fourth, or one-tenth, of the impedance for the differential mode signal, at least in one frequency range;

the impedance for the common mode signal may be zero, or less than one or more orders of magnitude, than the impedance for the differential mode signal, at least in a frequency range.

This differential mode isolation block thus makes it possible to inject or collect a common mode voltage on the differential lines while avoiding short-circuiting the differential lines towards the electrical ground or between them for the differential signal.

When the differential mode isolation block is implemented in a common mode transmitter, the common mode signal may be injected through the common mode connection. This signal in common mode can be by example generated by an oscillator of the transmitter in common mode connected to this common mode connection.

When the differential mode isolation block is implemented in a common mode receiver, the common mode signal can be collected at the common mode connection.

According to one embodiment, the differential mode isolation block may comprise inductances, called differential mode isolation, electromagnetically coupled in opposite directions and arranged to be respectively connected to a differential line on the one hand and to the common mode connection on the other hand.

Each isolation inductor can be a coil.

The differential mode isolation inductors being of opposite direction, the current due to the voltage across one of the inductances induces a polarity or opposite voltage across the other inductors.

The differential mode isolation block may comprise a ferromagnetic core around which the differential mode isolation inductors are wound in opposite winding directions, or connected in opposite directions or polarities, so as to achieve the electromagnetic coupling between said isolation inductors.

Such a ferromagnetic core is a simple and inexpensive way to achieve efficient electromagnetic coupling between insulation coils.

According to embodiments, the differential mode isolation block may comprise resistors, called differential mode isolation resistors, arranged to be connected respectively to a differential line on the one hand and to the common mode connection on the other hand. share.

According to one embodiment, at least one common-mode transmitter may comprise a feedback-type amplifier circuit including:

the output is connected in parallel with the isolation resistors of the differential mode, arranged to be respectively connected to the said at least two differential lines; and an input is connected in parallel with resistors, called feedback resistors, arranged to be respectively connected to said at least two differential lines.

The isolation resistors of the differential mode make it possible, as explained above, to avoid short-circuiting the differential lines towards the electrical earth.

The feedback resistors make it possible to measure the common mode voltage injected on the differential lines, so as to be able to compensate for the voltage drops in said differential mode isolation resistors.

The isolation resistors of the differential mode may preferentially be of identical value.

The parallel feedback resistances may preferably be of identical value.

The feedback amplifier type circuit may comprise an operational amplifier.

The common mode transmitter may further include an oscillator delivering the common mode signal to be injected into the differential lines.

In this embodiment, this oscillator may be connected to an input of the feedback amplifier type circuit or the operational amplifier.

According to one embodiment, at least one common-mode receiver may comprise a feedback-type amplifier circuit mounted as a voltage surge, and of which:

an input is connected in parallel with the isolation resistors of the differential mode, arranged to be respectively connected to said at least two differential lines; and

the output is connected to said input by at least one feedback resistor.

This circuit may include an operational amplifier.

It carries out a summation of the voltages present on the differential lines, which makes it possible to cancel the signal in differential mode to keep only the signal in common mode. The isolation resistors of the differential mode make it possible to avoid short-circuiting the differential lines towards the electrical ground, with regard to the differential signal.

The device according to the invention may comprise, for at least one differential communication module, a common mode isolation block with connections to the differential lines and so-called differential mode connections to the communication module, presenting a impedance for the common mode signal, between the connections to the differential lines and the connections to the differential communication module, greater than an impedance for the differential mode signal, between the connections to the differential lines.

The impedance for the common mode signal can be defined as the ratio, or the modulus of the ratio, between the common mode voltage (or the instantaneous average voltage) between the differential lines and the differential communication module, and the total current or the sum of the currents flowing between the differential lines and the differential communication module, in particular when this differential communication module has an impedance towards the low earth (differential emitter operation).

The impedance for the differential mode signal can be defined as the ratio, or the modulus of the ratio, between the voltage between the differential lines, and the current flowing between the differential lines via the common mode isolation block.

According to embodiments:

the impedance for the common mode signal may be equal to or greater than twice, or four times, or ten times the impedance for the differential mode signal, at least in one frequency range;

the impedance for the differential mode signal may be zero, or less than one or more orders of magnitude, than the impedance for the common mode signal, at least in a frequency range. Thus, the common mode isolation block makes it possible to inject, respectively receive, the signal in differential mode, while blocking the signal in common mode, and without disturbing the operation of the common mode.

According to an exemplary embodiment, the common mode isolation block may comprise inductances, called common mode isolation, intended to be respectively placed in series between the differential lines and the differential communication module, said isolation inductances. common mode being electromagnetically coupled together in a direction, or a polarity, the same.

Since the common mode insulation inductances are in the same direction, the current due to the voltage across one of the inductances induces a voltage of the same polarity or the same direction across the other of the inductances.

In particular, the common mode insulation block may advantageously comprise a ferromagnetic core around which the common mode insulation inductors are wound in identical winding directions, or connected in identical directions, so as to achieve the electromagnetic coupling. between said isolation inductors.

Advantageously, the device according to the invention may comprise, for at least one differential communication module, a module for connecting said differential communication module to the differential lines.

The connection module may include the common mode isolation block, and:

a first link interface with differential lines; and

a second interface for connection with the differential communication module, connected to said first interface downstream of the common mode isolation block, seen from said first interface.

Such a connection module thus makes it possible to make a simple and rapid connection of a differential communication module to the differential lines, by being inserted between said communication module differential and differential lines, like an adapter or connector.

Above all, such a connection module makes it possible to use existing differential communication modules, without having to intervene on said differential communication modules.

The connection module may further comprise a third interface connecting to a common mode transmitter, respectively to a common mode receiver, connected to the first interface upstream of the common mode isolation block, seen from said first interface.

Thus, the connection module allows to connect through the same interface with the differential lines, both the differential communication module and the common mode transmitter, respectively the common mode receiver.

In general, the invention may comprise the various elements that make it possible to convey a common-mode signal on an existing differential line, by being inserted on this line by exploiting existing connectors, without disturbing the operation of this differential line of the point. of differential communication.

The communication device may not include the communication bus in differential mode or the differential communication module (s), the latter (s) may be already present (s) within a device wherein said communication device is implemented.

Alternatively, the communication device according to the invention may further comprise:

a communication bus in differential mode with at least two differential lines; and

at least one communication module in differential mode.

The communication device according to the invention can be implemented in any type of equipment for conveying an excitation signal, or a signal timing, to functional units provided for performing a given function, such as measurement, detection, signaling, etc.

According to an advantageous application, the communication device according to the invention can be implemented in a capacitive detection device comprising a plurality of capacitive detection units.

According to another aspect of the same invention, there is provided a device for capacitive detection of an object, comprising at least one capacitive detection unit.

Each capacitive sensing unit may include:

at least one measuring electrode, and

a detection electronics for polarizing each measurement electrode at an alternating potential, called excitation potential, different from a ground potential, and measuring a signal relating to the electrode-object capacitance between each measurement electrode and said object.

Advantageously, the capacitive detection device according to the invention may further comprise a communication device according to the invention:

in which, the second signal injected in common mode by the common mode transmitter is used to generate the excitation signal, respectively synchronization signal, by each detection unit; and

comprising a common mode receiver of said second common mode signal for each detection unit.

Thus, the capacitive detection device makes it possible to use a communication bus in differential mode for the synchronization, and / or excitation, of several capacitive detection units.

As mentioned above, the communication bus in differential mode can be a bus already present within a device and used for communication between the various organs of said equipment. Therefore, it is not necessary to provide a first bus dedicated to the communication in differential mode and a second bus dedicated to the synchronization of the units of capacitive sensing, both functions being implemented with a single communication bus in differential mode.

Furthermore, according to a particularly advantageous characteristic, a differential mode communication module can be associated with each capacitive detection unit, for:

transmitting a detection signal supplied by said capacitive detection unit, and / or

receiving a configuration and / or control signal from said capacitive detection unit;

as the first transmitted signal, respectively received, in differential mode.

In addition, at least one capacitive sensing unit may further comprise at least one guard electrode biased to a guard potential identical or substantially identical to the excitation potential generated using the second signal.

The guard may be common to at least two, in particular all the measuring electrodes of said detection unit.

At least one guard electrode can be individual to a single measuring electrode.

According to yet another aspect of the same invention, there is provided equipment equipped with a capacitive detection device according to the invention.

According to embodiments of the equipment according to the invention:

the detection units can be reported to said equipment, and

the communication bus in differential mode can advantageously be a communication bus used in said equipment between different members of said equipment.

In addition, the differential mode communication modules may be modules present in said equipment with the communication bus in differential mode. The equipment may for example be in the form of a fixed or mobile robot, humanoid shape or other, or in the form of a robotic manipulator arm, or a robot arm or a robot segment , or an autonomous vehicle (AGV).

According to embodiments, the detection device can be integrated into a member of the equipment, such as a shell or a hood.

Alternatively, the detection device may be independent of a member of the equipment and be disposed in / on a member of said equipment removably or removably.

Description of the Figures and Embodiments

Other advantages and characteristics will appear on examining the detailed description of non-limitative examples, and the appended drawings in which:

- FIGURE 1 is a schematic representation of an exemplary embodiment of a communication device in differential mode, according to the state of the art;

FIG. 2 is a schematic representation of a first exemplary embodiment of a communication device according to the invention;

FIG. 3 is a schematic representation of a second exemplary embodiment of a communication device according to the invention;

FIG. 4 is a schematic representation of a nonlimiting exemplary embodiment of a differential mode isolation block that can be implemented in a communication device according to the invention;

- FIGURE 5a is a schematic representation of a non-limiting embodiment of a common mode transmitter that can be implemented in a communication device according to the invention;

FIG. 5b is a schematic representation of a non-limiting embodiment of a common mode receiver be implemented in a communication device according to the invention;

FIG. 6 is a schematic representation of a nonlimiting exemplary embodiment of a differential mode isolation block that can be implemented in a communication device according to the invention;

FIG. 7 is a schematic representation of a nonlimiting exemplary embodiment of a common mode isolation block that can be implemented in a communication device according to the invention;

FIG. 8 is a schematic representation of a non-limiting exemplary embodiment of signals conveyed in a communication device according to the invention;

FIG. 9 is a schematic representation of a first nonlimiting exemplary embodiment of a capacitive detection device according to the invention;

FIG. 10 is a diagrammatic representation of a second nonlimiting exemplary embodiment of a capacitive detection device according to the invention; and

FIG. 11 is a diagrammatic representation of a nonlimiting exemplary embodiment of a robot implementing a capacitive detection device according to the invention.

It is understood that the embodiments which will be described in the following are in no way limiting. It will be possible, in particular, to imagine variants of the invention comprising only a selection of characteristics described subsequently isolated 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 art. This selection comprises at least one feature preferably functional 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 from the state of the prior art. In particular, all the variants and all the embodiments described are combinable with each other if nothing stands in the way of this combination at the technical level.

In the figures, the elements common to several figures retain the same reference.

FIGURE 1 is a schematic representation of an exemplary differential mode communication bus.

The bus 100, shown in FIG. 1, comprises two differential communication lines 102 and 104, forming for example a differential pair, a line carrying the supply potential denoted V and an electric ground line GND.

The communication bus in differential mode 100 interconnects two communication modules 106 _I- 106 ₂ in differential mode. Each of the communication modules 106 can transmit, respectively receive, a first differential mode communication signal to respectively from the other of the communication modules 106. To do this each of the modules 106i and 106 ₂ can be selectively transmitter or receiver . In FIG. 1, the module 106i is an emitter and the module 106 ₂ is a receiver and receives the first signal embodied by the arrow 110.

In general, each of the modules 106 ₁ and 106 ₂ can be either transmitter or receiver only, or configurable as transmitter and receiver.

In FIGURE 1, only two differential lines are shown so as not to burden FIGURE 1. Of course, the power bus 100 may comprise more than two differential lines.

Similarly, in FIG. 1, only two differential modules 106 are shown so as not to weigh down FIG. 1. Of course, the communication bus 100 may be associated with more than two differential modules 106.

The communication bus 100 can operate for example according to the EIA-485 or RS-485 standard. More generally, it can be compliant with any other serial communication standard, 2-wire (half duplex), 4-wire (full duplex), etc., allowing the transfer of digital signals in differential mode, and in general to any standard of differential transmission that can support a common mode voltage sufficient to cover the amplitude of the signals to be transmitted and the operating margin. There may also be mentioned CAN type buses, and in general all physical layers on differential twisted pair type Ethernet (Ethercat, Profinet, etc.).

FIG. 2 is a schematic representation of a first exemplary embodiment of a communication device that can be implemented with the bus 100 of FIG. 1.

The device 200, shown in FIGURE 2, comprises all the elements of the device 100 of FIGURE 1.

The device 200 further comprises a common mode transmitter 202 for transmitting a second common mode signal on the differential lines 102 and 104. The second common mode signal is an alternating signal, in particular sinusoidal.

The common mode transmitter 202 includes an emitter differential mode isolation block 204, through which it is connected to each of the two differential lines 102 and 104. In general, this differential mode isolation block The transmitter 204 is used to inject the second common mode signal on the differential lines 102 and 104 without disturbing the first differential mode signal. For this, he must present:

a low impedance for the common mode signal, ie the second signal, so as not to excessively weaken this signal; and

a high impedance, or at least higher than the impedance for the common mode signal, for the differential mode signal, that is to say the first signal exchanged between the differential communication modules 106. It must also have a sufficiently high impedance between each differential line 102, 104 and GND ground under all circumstances not to short-circuit these lines.

Thus, the common-mode transmitter 202 can inject a common-mode signal on the differential lines 102 and 104 without overly short-circuiting or disturbing the differential mode. The device 200 also includes a common mode receiver 206 for receiving the common mode signal transmitted by the common mode transmitter 202, and carried by the differential lines 102 and 104.

Like the common mode transmitter 202, the common mode receiver 206 includes a receiver differential mode isolation block 208, through which it is connected to each of the two differential lines 102 and 104. Generally, this receiver differential mode isolation block 208 collects the second common mode signal on the differential lines 102 and 104 without disturbing the first differential mode signal. For this, as before, he must present:

Thus, the common mode receiver 206 may receive the common mode signal, embodied by the arrow 210, from the differential lines 102 and 104 without excessively short-circuiting or disturbing the differential mode.

The common mode receiver 206 may include one or more optional functional units 212 using the common mode signal 210.

Alternatively, or in addition, the common mode signal may be provided to at least one unit 214 external to the common mode receiver 206.

To avoid disturbing the differential modules 106 by the common-mode signal 210, the device 200 comprises for each differential module 106 _I- 106 ₂ , a common-mode isolation block, respectively 216 ₁ and 216 ₂ , inserted between said differential module and the differential lines 102-104. Thus, the differential module 106i is connected to the differential lines 102-104 through the common mode isolation block 216i and the differential module 106 ₂ is connected to the differential lines 102-104 through the common mode isolation block 216. ₂ .

Each common-mode isolation block 216 has the same function, ie, for each differential line 102-104, maintain its high impedance with respect to GND ground in common mode, without significantly changing its differential mode impedance.

FIGURE 3 is a schematic representation of a second embodiment of a communication device according to the invention.

The device 300, of FIGURE 3, comprises all the elements of the device 200 of FIGURE 2.

The device 300 further comprises a connection module 302 in which is integrated the common mode insulation block 216 ₂ associated with the differential module 106 ₂ .

Moreover, unlike the device 200 of FIGURE 2, in the device 300 of FIGURE 3, the connection of the differential lines 102 and 104 with the differential module 106 ₂ and the receiver common mode 206, is performed through the connection module 302.

To do this, the connection module 302 comprises:

a first interface 304 for connection with the differential lines 102 and 104;

a second link interface 306 with the differential module

106 ₂ : this second interface 306 is connected to the first interface 304 through the common mode insulation block 216 ₂ ; and

a third link interface 308 with the common mode receiver 206: this third interface 308 is connected to the first interface 304 upstream of the common mode isolation block 216 ₂ integrated in the connection module 302.

The connection module 302 has the advantage of being able to connect, with a single interface with the differential lines 102-104, both the common mode receiver 206 and the differential module 106 _{2 to} said lines. 102-104 differential, which is simpler, faster, and more ergonomic.

Of course, although not shown in FIG. 3, it is possible to provide a similar connection module for connecting the common mode transmitter 202 and the differential module 106i to the differential lines 102 and 104, and comprising the isolation block common mode 216i.

FIGURE 4 is a schematic representation of a non-limiting exemplary embodiment of a differential mode isolation block that can be implemented in a communication device according to the invention.

The differential mode isolation block 400, shown in FIG. 4, may be the emitter differential mode isolation block 204 of the common mode emitter 202 of FIGURES 2, 3 and 5a, or the block of FIG. the common mode receiver 206 differential mode isolation of FIGS. 2, 3 and 5b.

In other words, the differential mode isolation block 400 of FIGURE 4 can be used in the common mode transmitter 202 or the common mode receiver 206.

The differential mode isolation block 400 comprises a first isolation resistor 402 connected to the differential line 102, and a second isolation resistor 404 connected to the differential line 104. These isolation resistors 402 and 404 are connected between they according to their other terminal to a connection, called common mode, 406.

Under these conditions, the impedance Z _dlff between the differential lines 102 and 104, such that "seen" by the differential mode signal corresponds to 2R, with R the value of the isolation resistors, while the impedance Z _C M such that "seen" by the common mode signal corresponds to the parallel isolation resistors, R / 2. There is thus an impedance for the lower common mode signal, by a factor of 4, to the impedance for the differential mode signal. Moreover, even if the common-mode connection 406 is connected to the ground GND (for example via a common-mode signal source), the impedance between each differential line 102, 104 and GND mass corresponds at least the value of an insulation resistance R, thus higher than the impedance Z _C M such that it is "seen" by the signal in common mode.

In the common mode transmitter 202, a common mode signal is injected at the common terminals of the isolation resistors 402 and 404, for example by a voltage source or an oscillator. This common-mode signal is thus coupled to the differential lines 102 and 104 with a minimum voltage drop across the isolation resistors 402, 404. Conversely, in the common-mode receiver 206, the common terminals are obtained. common mode 406 of the isolation resistors 402 and 404 a signal corresponding to the common mode of the voltages on the differential lines 102 and 104. This signal corresponding to the common mode can be detected by any mounting, for example amplifier type.

FIGURE 5a is a schematic representation of a non-limiting embodiment of a common mode transmitter that can be implemented in a communication device according to the invention.

The common mode transmitter 202, shown in FIGURE 5a, may be the common mode transmitter 202 of FIGURES 2 and 3.

The common mode transmitter 202 includes the differential mode isolation block 400, and an oscillator 502 providing the common mode signal to be injected into the differential lines 102 and 104.

The common mode transmitter 202 comprises a circuit providing an operational amplifier 504 whose non-inverting input "+" is connected to the oscillator 502.

The output of the operational amplifier 504 is connected to each of the differential lines 102 and 104, through isolation resistors 402, 404 forming a differential mode isolation block 400 as previously described.

The inverting input "-" of the operational amplifier 504 is connected to each of the differential lines 102 and 104 by a feedback resistor R _m . Resistors R _m are intended to measure the common-mode voltage injected on the differential lines 102 and 104 to compensate for voltage drops in the isolation resistors 402, 404. According to an alternative embodiment (not shown), the operational amplifier 504 could comprise only a feedback resistor R _m connecting its inverting input "-" and its output, in a conventional feedback arrangement.

FIGURE 5b is a schematic representation of a non-limiting embodiment of a common mode receiver that can be implemented in a communication device according to the invention.

The common mode receiver 206, shown in FIG. 5, may be the common mode receiver 206 of FIGURES 2 and 3.

The common mode receiver 206 includes the differential mode isolation block 400.

The receiver 206 further comprises a feedback operation amplifier 506 connected according to its inverting input "-" to the isolation resistors 402, 404 of the differential mode isolation block 400. The non-inverting input "+" of the operational amplifier 506 is connected to GND ground.

The output of the operational amplifier 506 is looped back to its inverting input "-" by a feedback resistor R _f .

Under these conditions, the output of the operational amplifier 506 provides a summation of the voltages on the differential lines 102 and 104, and therefore the common mode signal 210, with an amplitude which is a function of the values of the resistors (or impedances) R , and R _f .

FIG. 6 is a diagrammatic representation of a nonlimiting exemplary embodiment of a differential mode isolation block that can be implemented in a communication device according to the invention.

The differential mode isolation block 600, shown in FIGURE 6, may be the differential mode isolation block 204 of the common mode transmitter 202 of FIGURES 2-3, or the differential mode isolation block. 208 of the common mode receiver 206 of FIGURES 2-3.

In other words, the differential mode isolation block 600 of FIGURE 6 can be used in the common mode transmitter 202 or the common mode receiver 206. On the other hand, the differential mode isolation block 600 may be used instead of the differential mode isolation block 400 as shown in FIGURES 5a-5b.

The differential mode insulation block 600 comprises a first inductor 602, for example formed by a coil, connected to the differential line 102, and a second inductor 604, for example formed by a coil, connected to the differential line 104. inductances 602 and 604 are connected together according to their other terminal, corresponding to a so-called common mode connection 608.

Inductors 602 and 604 are electromagnetically coupled in opposite directions. In particular, the differential mode insulation block 600 comprises a ferromagnetic core 606 around which the inductors 602 and 604 are wound in opposite winding directions, or wound in identical winding directions and connected in opposite directions or polarities. .

Under these conditions, a voltage applied across an inductor generates a voltage of opposite direction in the coupled inductance, by mutual inductance effect. It follows that, assuming a perfect electromagnetic coupling between inductances 602 and 604 of value L:

the impedance Z _diff between the differential lines 102 and 104, such as "seen" by the differential mode signal, is equal to 4Lco (where co is the pulsation), which is a high value. Moreover, the impedance between a differential line 102, 104 and the ground GND, in the event of a short circuit of the common mode connection 608, is at least equal to Lco, which is also a high value;

the impedance Z _CM , between the differential lines 102 and 104 on the one hand and the ground GND on the other hand, such as "seen" by the signal in common mode, is zero or almost zero.

Thus, in the common mode transmitter 202, a common-mode signal (for example from an oscillator) injected at the common terminals of the inductors 602 and 604 is thus coupled on the differential lines 102 and 104 with virtually no losses. Conversely, in the common mode receiver 206, there is obtained at the common terminals of the inductors 602 and 604 a signal corresponding to the common mode of the voltages on the differential lines 102 and 104. The differential mode signal is also not significantly disturbed.

FIGURE 7 is a schematic representation of a nonlimiting exemplary embodiment of a common mode isolation block that can be implemented in a communication device according to the invention.

The insulation block common mode 700, shown in FIGURE 7 can be the insulation block of the common mode 216i 106i differential module, or common mode isolation block 216 ₂ of the differential module 106 of FIGURES ₂ 2-3.

The common mode insulation block 700 comprises a first inductor 702, for example formed by a coil, connected to the differential line 102, and a second inductor 704, for example formed by a coil, connected to the differential line 104.

The inductors 702 and 704 are connected respectively to each input and / or differential output of the differential communication modules (106 _I , 106 ₂ ).

The inductors 702 and 704 are electromagnetically coupled in identical directions or polarities. In particular, the insulation block 700 comprises a ferromagnetic core 706 around which the inductors 702 and 704 are wound in identical winding directions, and of course connected in identical directions.

Under these conditions, a voltage applied across an inductor generates a voltage of the same direction in the coupled inductance, by mutual inductance effect. It follows that, assuming a perfect electromagnetic coupling between inductances 702 and 704 of value L:

the impedance Z _diff between the differential lines 102 and 104 due to the inductances 702 and 704, such as "seen" by the signal in differential mode, is very low, or even zero;

the impedance Z _C M for each inductance, between the differential lines 102 and 104 on the one hand and the ground GND on the other hand, such as "seen" by the signal in common mode, remains high, of the order of Lco, whatever the state (transmitter or receiver) of the differential communication module 106 to which the inductors 702, 704 are connected. Thus, on the one hand the transmission of the differential signal in the differential module is not significantly disturbed, and on the other hand the state of the differential module (in transmitter or in receiver) does not significantly affect the signal in common mode. .

FIGURE 8 is a schematic representation of an exemplary signal conveyed by the differential lines, superimposing the differential mode signal and the common mode signal.

FIGURE 8 shows the common mode signal 210, initially injected into each differential line 102 and 104.

The line 802 shows the signal conveyed by the differential line 102, obtained by adding the common mode signal 210 to the differential mode signal.

Line 804 shows the signal conveyed by the differential line 104, obtained by adding the common mode signal 210 to the differential mode signal.

Thus, it seems clear that by averaging or summing the signals conveyed by the differential lines 102 and 104, the common-mode signal 210 is found.

In addition, the signal transmitted by each differential line has a peak voltage of between + 7V and -7V, which is compatible with the communication bus in differential mode.

FIGURE 9 is a schematic representation of a first nonlimiting exemplary embodiment of a capacitive detection device.

The capacitive sensing device 900, shown in FIGURE 9, comprises a capacitive sensing unit 902.

The capacitive sensing unit 902 includes a plurality of measuring electrodes 904 and at least one guard electrode 906 for electrically holding the measurement electrodes 904.

The capacitive detection unit 902 further comprises a detection electronics 908, analog and / or digital, for: biasing the measurement electrodes 904 and the guard electrodes 906 to the same excitation potential V _G , which is different from a mass potential at a given frequency, and

measuring a signal relating to the electrode-object capacitance between each measurement electrode 904 and an object that is in proximity or in contact with said measuring electrode.

The detection electronics 908 comprise a current or charge amplifier 910 represented by an operational amplifier (AO) 912 and a feedback capacitance 914 looping the GAO 912 output to the "-" inverter input. GAO 912.

This detection electronics 908 can be referenced to the excitation potential V _G , or GND ground.

In addition, in the example shown, the non-inverting input "+" of GAO 912 receives the potential V _G and the inverting input "-" of GAO 912 is provided to be connected to each measuring electrode 904 by means of FIG. intermediate polling means 916, which may be for example a switch, so as to individually interrogate in turn all the measurement electrodes 904.

Under these conditions, the charge amplifier 910, and in particular GAO 912, supplies at the output a voltage or a signal V _s of amplitude proportional to the coupling capacitance C _eo , referred to as the electrode-object capacitance, between the measurement 904 connected to its inverting input "-" and an object near or in contact with said measuring electrode.

The detection electronics 908 may further comprise a conditioner 918 making it possible to obtain a signal representative of the desired coupling capacitance C _eo or of a quantity derived from this capacitance, such as distance or contact information. This conditioner 918 may comprise, for example, a synchronous demodulator for demodulating the signal with respect to a carrier, at a working frequency. Conditioner 918 may also include an asynchronous demodulator or an amplitude detector. This conditioner 918 can, of course, be made in an analog and / or digital form (microprocessor) and include all necessary means of filtering, conversion, treatment, etc.

At the output, the capacitive detection unit 902 supplies the value of the signal V _s , which is therefore representative of the coupling capacitance C _eo sought, or of a quantity derived from this capacity, such as distance or contact information.

The capacitive sensing device 900 includes the common mode transmitter 202 which transmits a common mode signal on the differential lines 102 and 104.

The capacitive sensing device 900 further comprises a common mode receiver 206 associated with the capacitive sensing unit 902.

The common-mode signal emitted by the common mode transmitter 202 is received by the common mode receiver 206. The common-mode signal detected by the common mode receiver 206 is supplied to the capacitive detection unit 902 for:

- be used directly as excitation potential V _G , as shown in FIG 9; or

- be used to generate the excitation potential V _G.

In addition, the capacitive sensing device 900 includes a differential mode communication module 106, and its common mode isolation block 216. The differential module 106 is connected to the output of the capacitive detection unit 902. This differential module 106 thus receives the signal V _s supplied by the detection unit 902, and transmits it in the differential lines 102 and 104, in the differential and according to the protocol of this differential interface. This information, namely in particular the value of the signal V _s , is communicated, in differential mode, to another differential communication module (not shown) which may for example be associated with a capacitive detection management unit (not shown). . Of course, the differential module 106 can operate in transmission and reception to receive configuration information, trigger measurement, ... and transmit all the information from the capacitive sensing device 900.

FIGURE 10 is a schematic representation of a second nonlimiting exemplary embodiment of a capacitive detection device. The capacitive sensing device 1000, shown in FIGURE 10 includes "n" capacitive detection unit 902i-902 _n, n³ l.

The capacitive sensing device 1000 also includes the common mode transmitter 202 for transmitting the excitation signal to be used in each capacitive sensing unit 902 ,, and in particular the potential V _G.

To do this, each detection unit 902 is associated with a common mode receiver module 206 to receive the excitation signal emitted in common mode by the transmitter 202 in common mode.

In addition, each detection unit 902 is associated with a differential mode communication module 106, and its common mode isolation block 216, for differentially transmitting the information from said detection unit 902. to a capacitive sensing management unit (not shown), and receive commands and other information from this capacitive sensing management unit.

Of course, the capacitive sensing devices can implement the connection device 302 of FIGURE 3 for at least one particular each differential communication module.

FIGURE 11 is a schematic representation of a robot equipped with a capacitive detection device according to the invention.

The robot 1100, shown in FIGURE 11, is a robotic arm comprising a plurality of articulated segments, and interconnected by rotary joints.

The robot 1100 has two cladding elements 1102 and 1104 disposed on two segments of the robot 1100.

Each covering element 1102-1104 comprises a detection unit, such as, for example, the detection unit 902 of FIG. 9.

Each detection unit receives the excitation signal V _G , and transmits the measurement signal V _s (in particular), as described above with reference to FIGURES 9 and 10.

The measurement electrodes 904 of each detection unit equipping the covering elements 1102-1104 are integrated into the thickness of said element covering, or deposited on one or the faces of said covering element 1102-1104.

The skin elements 1102-1104 are used either in place of an original cladding element of the robot, or in addition to an original cladding element.

In this type of application, it is important that the measuring electrodes 904 belonging to separate cladding elements 1102-1104 do not detect each other, so as not to disturb the operation of the device. This is achieved by virtue of the invention by transmitting to all the cladding elements 1102-1104 the same common mode signal making it possible to generate the same excitation potential V _G.

Of course, the invention is not limited to the examples that have just been described and many adjustments can be made to these examples without departing from the scope of the invention.

Claims

A communication device (200; 300) for implementation with a differential mode communication bus comprising at least two differential lines (102, 104) for carrying a first differential mode signal (110) between at least two modules of differential communication (106 _I , 106 ₂ ), characterized in that it further comprises:

- At least one transmitter (202) in common mode, for injecting the same second signal (210), said common mode, alternating, on each of said at least two differential lines (102, 104), at a point of said communication bus; and

- At least one receiver (206) in common mode, for receiving said second signal (210), at another point of said communication bus.

2. Device (200; 300) according to the preceding claim, characterized in that at least one common mode transmitter (202), and / or at least one receiver (206) in common mode comprises a block (204,208; 400; 600), said differential mode isolation, with a connection to each differential line (102, 104) and a so-called common mode connection, having an impedance for the common mode signal (210), between the connections to the differential lines ( 102, 104) and the common mode connection, less than an impedance for the differential mode signal (110), between said connections to the differential lines (102, 104).

3. Device (200; 300) according to the preceding claim, characterized in that the differential mode isolation block (600) comprises inductances (602,604), called differential mode isolation, electromagnetically coupled in opposite directions and arranged to be respectively connected to a differential line (102, 104) on the one hand and to the common mode connection on the other hand.

4. Device (200; 300) according to the preceding claim, characterized in that the differential mode isolation block (600) comprises a ferromagnetic core (606) around which the mode insulation inductors differential (602,604) are wound in opposite winding directions, or connected in opposite directions, so as to achieve the electromagnetic coupling between said inductances.

5. Device (200; 300) according to claim 2, characterized in that the differential mode isolation block (400) comprises resistors (402, 404), called differential mode isolation, arranged to be respectively connected to a differential line (102,104) on the one hand and the common mode connection on the other hand.

6. Device (200; 300) according to the preceding claim, characterized in that at least one transmitter (202) in common mode comprises a feedback-type amplifier circuit (504) including:

the output is connected in parallel with the isolation resistors of the differential mode (402, 404), arranged to be respectively connected to the said at least two differential lines (102, 104); and

an input is connected in parallel with so-called feedback resistors, arranged to be respectively connected to said at least two differential lines (102, 104).

7. Device (200; 300) according to claim 5, characterized in that at least one receiver (206) in common mode comprises a feedback-type amplifier circuit (506) mounted voltage adder, and including:

an input is connected in parallel with the differential mode isolation resistors (402, 404), arranged to be respectively connected to said at least two differential lines (102, 104); and

the output is connected to said input by at least one feedback resistor.

8. Device (200; 300) according to any one of the preceding claims, characterized in that it comprises, for at least one differential communication module (106 _I, 106 ₂ ), a common mode isolation block ( 216 _I , 216 ₂ , 700), with connections to the differential lines (102, 104) and so-called differential mode connections to the communication module, having an impedance for the common mode signal (210), between the connections to the differential lines (102, 104) and the connections to the differential communication module (106 _I, 106 ₂ ), greater than an impedance for the differential mode signal (110), between the connections to the differential lines.

9. Device (200; 300) according to the preceding claim, characterized in that the common mode insulation block (700) comprises inductances (702, 704), called common mode insulation, intended to be respectively placed in series between the differential lines (102, 104) and the differential communication module (106 _I, 106 ₂ ), said common mode isolation inductors (702, 704) being electromagnetically coupled together in a direction, or an identical polarity.

10. Device (200; 300) according to the preceding claim, characterized in that the common mode insulation block (700) comprises a ferromagnetic core (706) around which the common mode insulation inductances (702, 704) are wound according to identical winding directions, or connected in identical directions, so as to perform the electromagnetic coupling between said insulation inductances (702, 704).

11. Device (300) according to any one of claims 8 to 10, characterized in that it comprises, for at least one differential communication module (106 ₂ ), a connection module (302) of said differential communication module (106 ₂ ) to the differential lines (102, 104), said connection module (302) comprising the common mode isolation block (216 ₂ ) and:

a first link interface (304) with the differential lines (102, 104); and

a second link interface (306) with the differential communication module (160 ₂ ), connected to said first interface (304) downstream of the common mode isolation block (216 ₂ ), seen from said first interface (304); ).

12. Device (300) according to the preceding claim, characterized in that the connection module (302) comprises a third interface link (308) to a common mode transmitter, respectively to a common mode receiver (206), connected at the first interface (304) upstream of the common mode isolation block (216 ₂ ), seen from said first interface (304).

Communication device (200; 300) according to any one of the preceding claims, characterized in that it further comprises:

a communication bus in differential mode with at least two differential lines (102, 104); and

- At least one communication module (106 _I , 106 ₂ ) in differential mode.

Apparatus (900; 1000) for capacitive sensing of an object comprising at least one capacitive sensing unit (902, each comprising:

at least one measuring electrode (904), and

a detection electronics (908) for biasing each measuring electrode (904) to an alternating potential, called an excitation potential, different from a ground potential (GND), and measuring a signal relating to the electrode-object capacitance between each measuring electrode (904) and said object;

said capacitive sensing device (900; 1000) further comprising a communication device (200; 300) according to any one of the preceding claims:

in which, the second signal injected in common mode by the common-mode transmitter is used to generate the excitation signal (V _G ), respectively synchronization signal, by each detection unit (902); and

- including a common mode receiver (206) of said second common mode signal for each detection unit (902).

Device (900; 1000) according to claims 13 and 14, characterized in that a differential mode communication module (106) is associated with each capacitive detection unit (902) for:

transmitting a detection signal supplied by said capacitive detection unit (902), and / or

receiving a configuration and / or control signal from said capacitive detection unit (902);

as the first transmitted signal, respectively received, in differential mode.

16. Device (900; 1000) according to any one of claims 14 or 15, characterized in that at least one capacitive detection unit (902) comprises at least one guard electrode (906) biased to a guard potential (V _G ), identical or substantially identical to the excitation potential, generated using the second signal.

17. Equipment (1100) provided with a detection device according to any one of claims 14 to 16.

18. Equipment (1100) according to the preceding claim, characterized in that:

the detection units are reported to said equipment (1100), and

the communication bus in differential mode is a communication bus used in said equipment (1100) between different members of said equipment (1100).

19. Equipment (1100) according to the preceding claim, characterized that it is a robot, a robotic manipulator arm or a robot segment.