RING-SHAPED TOUCH SENSOR AND ASSOCIATED HUMAN-MACHINE INTERFACE

Abstract

Sensor assembly (CAPT) comprising a substantially cylindrical annular element (ANN) and at least two strain sensors (SENS1, SENS2, SENS3) mounted on the annular element at levels of at least two distinct radii (r1, r2, r3) from it, respectively, so as to be sensitive to a deformation of the annular element. Figure to be published with the abbreviation: Fig. 1

Description

Title of the invention: RING-SHAPED TOUCH SENSOR AND ASSOCIATED HUMAN-MACHINE INTERFACE TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to a ring-shaped sensor, and extends to human-machine interfaces, systems allowing a user to control interactive systems, and is therefore in the field of human-machine interactions sometimes referred to by the acronym HMI. TECHNOLOGICAL BACKGROUND

[0002] Human-machine interfaces come in many forms, allowing a user to interact with an electronic system, such as a computer, robot, television, sound reproduction system, or game console. These interfaces are designed to i) generate control signals from a user action, and then ii) transmit these signals to the electronic system.

[0003] The wide variety of possible actions for a user to control the electronic system has been used to design various types of interfaces: these can be a keyboard, a mouse, a touch screen, an optical detection system, a microphone or a joystick, all equipped with sensors (contact, infrared, magnetometer, optical, camera, accelerometer, gyroscope...) whose function is to detect a specific action of the user (movement, gesture, speech, action...).

[0004] Among these various types of interfaces, development efforts have focused on ring-shaped devices, generally intended to be worn around a user's finger, as described in US patent 9,582,076 B2 and US patent application 2017 / 0242496 AL. Such devices have the advantages of minimal bulk, allowing them to be worn without hindering the user, but require complex sensors such as cameras for analyzing the ring's immediate environment. These sensors generate signals whose processing involves computationally intensive tasks, necessitating high-performance electronics, which are expensive and reduce the battery life of these interfaces. Furthermore, this complexity negatively impacts control reliability.

[0005] Still with regard to ring-shaped devices, there are simpler design systems, such as a ring with eight outer faces described in the article by Hyunchul Lim et al., “OctaRing: Examining pressure-sensitive multi-touch input on a finger ring device”, UIST 2016 Adjunct - Proceedings of the 29th Annual Symposium on User Interface Software and Technology, Association for Computing Machinery, Inc., pages 223-224. Each of the eight faces is equipped with a pressure sensor intended to be directly pressed by the user. Various control signals can be generated depending on the pressure sensors pressed simultaneously.

[0006] Another device, a ring intended to be grasped with two hands by the user at two diametrically opposed areas, is described in US patent application 2022 / 0212112 A1. It comprises a flexible ring mounted on a base equipped with a deformation sensor, the assembly being configured to generate a signal representative of the amplitude of deformation of the flexible ring when the user deforms the ring by bringing their hands together.

[0007] However, a human-machine interface having a general ring shape, of simple design while allowing the generation of various control signals remains to be defined. Description of the invention

[0008] The applicant's objective is to propose, on the one hand, a ring-shaped touch sensor, and, on the other hand, an application of this touch sensor to a human-machine interaction device in the form of a ring sensitive to a deformation caused by a user.

[0009] For the purpose of achieving this goal, a first aspect of the invention is a sensor assembly comprising an annular element of substantially cylindrical shape and at least two strain sensors mounted on the annular element at levels of at least two distinct radii from it, respectively, so as to be sensitive to a deformation of the annular element.

[0010] According to additional non-limiting features of the sensor according to the invention, considered individually or in any technically feasible combination:

[0011] - the at least two distinct beams can be angularly spaced apart from each other at an angle between 20° and 160°; and

[0012] - the at least two strain sensors may be piezo type sensors electric.

[0013] Such a sensor allows the detection of a wide variety of actions on the annular element forming its mechanical structure.

[0014] A second object of the invention is a human-machine interface comprising the sensor assembly according to the invention, further comprising an acquisition module configured to generate a detection signal in response to a deformation of the annular element based on signals emitted by at least two deformation sensors, the human-machine interface being configured so as to generate control signals from a device external to the human-machine interface in response to the detection signal. Such an interface allows for the simple, precise, and time-dependent characterization of ring deformation based on local deformations measured by sensors. Various control signals from an external device can be associated with the occurrences and temporal variations of the deformation, providing great flexibility of use compared to the device's simplicity. Thus, various user actions on the ring can be associated with as many control signals from the external device.

[0015] This is an interface that does not infringe on the user's privacy since it does not rely on the acquisition and processing of video or audio signals that could contain personal information. This interface is very well suited to integration into jewelry with a classic appearance, including small pieces.

[0016] According to additional non-limiting features of the sensor according to the invention, considered individually or in any technically feasible combination:

[0017] - the detection signal can be one of a detection signal for an action of short ring tightening, a detection signal for a long ring tightening action, a detection signal for a double ring tightening action, a signal representing the location of any of the previous actions, a detection signal for a finger tap action, a detection signal for a ring tap action, a detection signal for a negative direction rotation action, and a detection signal for a positive direction rotation action;

[0018] - the acquisition module can be configured to detect when a threshold is exceeded by a quantity representative of an amplitude of a signal or a combination of signals each representative of a deformation of the annular element and generated by one or more sensors of the at least two deformation sensors, and, in response to this detection, generate a signal representative of the occurrence of an action applied to the annular element;

[0019] - the acquisition module can be configured to keep only one awake first part of the acquisition module associated with detection and only activate the second parts of the acquisition module when it is determined that respective activations of these second parts are necessary for signal analysis;

[0020] - the acquisition module can be configured to: detect a rotation of the ring based on the first signal and the second signal; and in response to the detection step, generate a signal representative of the occurrence of a rotation of the annular element;

[0021] - the acquisition module is further configured to: on the basis of at least two signals, generate a signal representative of the fact that a substantially constant localizing pressure action has been applied to the ring by a user; and in in response to this detection, generate one of a detection signal of a short ring tightening action, a detection signal of a long ring tightening action, a detection signal of a double ring tightening action, a signal representing a location of any of the three previous actions, a detection signal of a finger tap action, and a detection signal of a ring tap action;

[0022] - the acquisition module can be configured to: implement an operation frequency content analysis of signals; and in response to the frequency content analysis of signals, generate one of a signal for detecting a finger tap action and one of a signal for detecting a ring tap action;

[0023] - the acquisition module can be configured to: detect peaks in a amplitude of at least one of the signals; and in response to the number of peaks detected, generate one of a detection signal of a short tightening action of the ring, one detection signal of a long tightening action of the ring, one detection signal of a double tightening action of the ring;

[0024] - the human-machine interface according to the invention may further comprise a module wireless transmission configured to transmit signals generated by the acquisition module to the external device and a power supply for the wireless transmission module and the acquisition module;

[0025] - the human-machine interface according to the invention may further comprise a feedback device configured to notify a user when the acquisition module generates a detection signal; and

[0026] - the human-machine interface according to the invention can be configured to be threaded on a part of a user or a rod of an external device control.

[0027] The interface according to the invention can be compact and passive when piezoelectric strain sensors are used, and the processing of the signals generated by these sensors can be simple and computationally lightweight, resulting in high autonomy of the device. Furthermore, the ring strain detection can be highly sensitive and can therefore operate without difficulty even with very rigid rings such as thick metal rings, like those commonly worn in jewelry.

[0028] The invention extends to a kit comprising a human-machine interface according to the invention. BRIEF DESCRIPTION OF THE FIGURES

[0029] Other features and advantages of the invention will become apparent from the detailed description of the invention which follows with reference to the accompanying figures in which:

[0030] [Fig.1] Fig.1 represents a sensor assembly and a human-machine interface according to the invention, taking the form of a ring equipped with sensors;

[0031] [Fig.2] The [Fig.2] represents modes of use of the ring;

[0032] [Fig.3] The [Fig.3] represents structural features of the ring;

[0033] [Fig.4] The [Fig.4] is a functional diagram of elements constituting the ring;

[0034] [Fig.5] The [Fig.5] illustrates signals generated by the ring in response to pressure on a first sensor of the ring;

[0035] [Fig.6] Fig.6 illustrates signals generated by the ring in response to pressure on a second sensor of the ring;

[0036] [Fig.7] The [Fig.7] illustrates signals generated by the ring in response to pressure on a third sensor of the ring;

[0037] [Fig.8] Fig.8 illustrates signals generated by the ring in response to two successive pressures on the ring sensors;

[0038] [Fig.9] Fig.9 represents signals generated by the ring in response to long and short ring tightening;

[0039] [Fig. 10] The [Fig. 10] illustrates signals generated by the ring during rotational actions in opposite directions;

[0040] [Fig. 11] The [Fig. 11] is a representation of signals generated by the ring during a rotation action;

[0041] [Fig. 12] The [Fig. 12] illustrates signals generated by the ring in response to a tap of a finger wearing the ring on a table;

[0042] [Fig. 13] The [Fig. 13] illustrates signals generated by the ring in response to the ring being struck on a table;

[0043] [Fig. 14] The [Fig. 14] represents signals generated by the ring in response to taps at the sensors;

[0044] [Fig. 15] The [Fig. 15] represents a first and a second block of an algorithm for using the ring;

[0045] [Fig. 16] The [Fig. 16] illustrates the location of a point on the ring;

[0046] [Fig. 17] The [Fig. 17] represents a third block of the ring usage algorithm;

[0047] [Fig. 18] Figure 18 represents a fourth block of the ring usage algorithm; and

[0048] [Fig. 19] The [Fig. 19] represents variations in the structure of the sensor assembly of the [Fig.1]. DETAILED DESCRIPTION OF THE INVENTION

[0049] An embodiment of the present invention is described by means of Figures 1 to 19 and the associated passages below. Figures 1 to 4 and 19 give examples of the invention. Training on the structure, use and operating principle of the human-machine interaction ring. Figures 5 to 18 detail the processing of signals generated by the deformation sensors following manipulation of the ring by a user.

[0050] Figure 1 illustrates the structure and general operating principle of the ring according to the invention, with (A) a perspective view of a CAPT sensor assembly according to the invention, comprising an annular element ANN instrumented by three sensors SENS1, SENS2, and SENS3. These sensors are conventional strain sensors, for example, resistive gauges, whose electrical resistance varies with their deformation, or piezoelectric sensors. The latter are strain sensors based on a piezoelectric measuring element, that is, they take advantage of the piezoelectric behavior of a material to transform into an electrical signal a deformation it undergoes under the effect of external forces, for example, when it is bonded to a surface and that surface deforms.

[0051] This ring instrumentation allows it to be coupled with an electronic module (EL) to form a human-machine interface for controlling, for example, an electronic device such as a computer, a smartphone, a television, or a media player. In this example, three piezoelectric strain sensors, SENSi to SENS3, are bonded to the ring element, on which the electronic module (EL) is mounted. This module is configured to measure the electrical charges or voltage generated by the sensors, analyze them, and transmit the information wirelessly to an external device such as those mentioned above.

[0052] As illustrated in (B) of [Fig. 1], when the ring R is held between two fingers Fl and F2, a pressure force F is applied on both sides of the ring by the fingers, creating an overall deformation of the ring that can be characterized using the three sensors SENS1 to SENS3. More generally, and as will be detailed below, the detection of this deformation, whether a single or repeated event, and the profile of this deformation, corresponding for example to pressure between the fingers or to a strike, can be used to generate a control signal for an external device APP.

[0053] As illustrated in (C) of [Fig.1], when the ring is rolled between the fingers in a rotational movement Rot caused by the combination of the pressure force F and the displacements Dplt of the fingers Fl and F2, the position at which this force is applied moves substantially, and this displacement can be measured by comparing the signals from the three sensors.

[0054] Various user actions on the ring can thus be detected and associated with predetermined actions, such as (i) a simple press by pinching between the fingers associated with a validation action, (ii) a double press associated with an action (iii) returning to the back of a menu in a ring-controlled application, (iv) rotating the ring in either direction while controlling scrolling up or down in a list or the volume of a music player, and (v) tapping the ring on a hard surface such as a table or directly tapping the ring on a hard surface such as a table while performing confirmation actions equivalent to a single or double click of a computer mouse. The pressure applied to the ring, the taps, or the rotation speed can also be associated with specific commands.

[0055] It should be noted that the ring used as an example in this embodiment is equipped with three sensors, but a ring with two sensors, the minimum number required to spatially characterize the ring's deformation, would also work. Using three sensors provides redundancy and an additional measurement, enabling discrimination in ambiguous situations. It is also possible to use a larger number of sensors, with the disadvantages of increased integration and cost of the ring, as well as a more complex electronic processing system to be integrated onto the ring element, requiring more electrical contact traces and signal processing channels. The advantage, however, is improved robustness of event detection.

[0056] Also, the SENSi, SENS2 and SENS3 sensors are shown located on the outer surface of the ring, but they could also be located on its inner surface, or even integrated into the volume of the annular element, for example by being sandwiched between two concentric rings.

[0057] In (C), [Fig.3] illustrates a ring equipped with two sensors SENSi and SENS2 arranged on the inner surface of the ring, substantially at 90° to each other (the respective radii rl and r2 make an angle of substantially 90° to each other).

[0058] The respective positions of the sensors on the ring are located by means of rays, the center of one of the sensors defining a reference ray, the positions of the other sensors being located by the angles that the rays passing through their respective centers (in a cross-sectional view along the axis of revolution of the ring) make with the initial ray. In the example of [Fig. 3] in (A), the three sensors are arranged substantially homogeneously around the ring, at angular intervals of approximately 120°. In this case, the ray r1 associated with sensor SENS1 can be considered the reference ray, the rays r2 and r3 associated respectively with sensors SENS2 and SENS3 being located at approximately 120° and 240° respectively from the ray r1.

[0059] There is no strict requirement to be observed in the relative positioning of the sensors, except that it is advisable to avoid placing two sensors in diametrically opposite positions if one wishes to spatially characterize the deformation related to a pressure exerted at two diametrically opposite points, by For example, between two of the user's fingers: such a symmetrical positioning of the two sensors limits the spatial characterization capabilities of the deformation. It is also preferable to space the two sensors sufficiently apart to facilitate this spatial characterization, which is all the easier when the deformations measured by the sensors have different amplitudes.

[0060] Thus, it is preferable that the radii defining the positions of the sensors be spaced angularly between 20° and 160°, more preferably between 40° and 140°. Of course, the angles used may depend on the number of sensors integrated on the ring.

[0061] The ring may also be equipped with a feedback device (FB), informing the user that their manipulation of the ring by tightening, tapping, or rotating it has been registered. The FB device may be of any type conventionally used for this purpose, such as a light, sound, or haptic device.

[0062] The ring can be manipulated by threading it onto a part of a user, and in particular onto a finger F3 of a hand H as illustrated in (A) of [Fig. 2], or threaded onto a rod or wand RD of an external device control system as in (B) of [Fig. 2]. It is of course possible to construct the ring so that it can be worn, for example, on the user's wrist, arm, or leg. Alternatively, the ring can be used "free" without being threaded onto any part, as illustrated in [Fig. 1].

[0063] The ring preferably has dimensions that make it suitable for slipping onto a finger like a piece of jewelry such as a ring, with, for example, an inner diameter ¢, illustrated in (A) of [Fig. 3], of between 1 and 3 cm and a length L, illustrated in (B) of [Fig. 3], along its axis of between 2 mm and 2 cm. Furthermore, the ring is not necessarily a closed ring, but can also be an open ring with a cut C, as illustrated in (C) of [Fig. 3].

[0064] Figure 4 illustrates the elements integrated on a ring R and the functional relationships between the elements composing it and with an external device. Thus, the ring R comprises, in a two-sensor configuration, two sensors SENSi and SENS2 connected to an electronic module EL for processing the signals from the sensors.

[0065] The electronic module EL includes an ACQ acquisition module in which an analog-to-digital converter CONV receives the analog signals from the SENSi and SENS2 sensors and converts them into digital signals processed by a CALC digital computer. The digital computer processes the digital signals, generates detection signals in response to the digital signals, and generates control signals for an external APP device based on detection signals are sent to a COM communication module. The COM communication module's function is to transmit, preferably wirelessly, the generated control signals to the APP external device, located away from the R ring.

[0066] The CALC computer is also configured to, if necessary, control the FB feedback device and trigger an action indicating to the ring user that their action on the ring has been taken into account to send a control signal to the external APP device.

[0067] A battery BAT provides the energy required for the operation of the analog-to-digital converter CONV, the digital computer CALC, the communication module COM, and the feedback device FB. If the sensors are resistive gauges, the battery can also be used to supply them with electrical current.

[0068] Optionally, the battery can be charged by means of an EH energy harvesting device, or “Energy Harvesting” in English terminology, such as a miniature electromechanical device configured to conventionally harvest energy from ambient vibrations or user movements of the ring R.

[0069] Principles of event detection

[0070] Several types of user actions can be applied to the ring, each type of action being associated with a given command of the external device. The methods for detecting these types of actions are explained below, using the ring illustrated in [Fig. 1], which is equipped with three sensors evenly distributed around the periphery of the ring. Similar results would be obtained with a different number of sensors or sensors distributed differently. The explanations below are intended to illustrate the principles on which the practitioner can base their implementation of the ring according to the invention with various sensor configurations in terms of number and location.

[0071] In the figures mentioned below, the references SI, S2 and S3 are associated respectively with the signals generated by the three sensors Sensi, Sens2 and Sens3. The reference "S" represents the signals S2 and S3, the reference T represents time. The references S, SI and T are expressed in mV, mV and s respectively.

[0072] Tightening

[0073] The action of squeezing the ring between two fingers, as illustrated in [Fig. 1] in (B), is referred to here as "tightening". This figure illustrates a situation in which the SENS2 sensor undergoes elongation and the SENS1 and SENS3 sensors undergo compression.

[0074] A clamping action can be detected by exceeding a detection threshold THR0 by the amplitudes of the signals generated by the sensors.

[0075] It is also possible to detect not only the occurrence of the application of a clamping force, but also its angular location on the ring. Indeed, depending on the location of the applied clamping force, the three sensors will provide different signals. An analysis of the relationships between the signals makes it possible to determine the location of the applied clamping force, either by ab initio simulation of the ring, or by calibrating it. The clamping force location is understood to mean the determination of an angle between 0° and 180° defining the position of one of the two fingers applying the clamping pressures relative to a reference angle, for example defined by the radius rl of the SENSp II sensor. It is assumed that the second finger applies pressure at a location diametrically opposite to that of the first finger.

[0076] Figures 5, 6, and 7 illustrate the results of three experimental situations in which the ring is tightened such that one of the two fingers applying the tightening action is located at the level of sensors SENS1, SENS2, and SENS3, respectively, with the other finger located diametrically opposite the first finger. Figure (A) shows graphs of the amplitudes of signals S2 and S3 generated by sensors SENS2 and SENS3, respectively, as a function of the amplitude of signal S1 generated by sensor SENS1. Figure (B) shows graphs of the amplitudes of the signals generated by sensors SENS1, SENS2, and SENS3, based on the same data as the corresponding graphs in (A), but expressed this time as a function of time T.

[0077] When, as in [Fig. 5], one of the fingers applying the clamp is located on the SENS1 sensor, the two curves illustrated in (A) trace approximately straight lines of the same slope. This is due to the symmetry of the ring, which causes the mechanical load to be distributed symmetrically at the levels of the SENS2 and SENS3 sensors.

[0078] When, as in [Fig.6], one of the fingers performing the clamping is located on the SENS2 sensor, the curve corresponding to the SENS2 sensor forms approximately a straight line of negative slope while the curve corresponding to the SENS3 sensor forms approximately a straight line of positive slope.

[0079] When, as in [Fig.7], one of the fingers performing the clamping is located on the SENS3 sensor, the curve corresponding to the SENS2 sensor forms approximately a straight line of positive slope while the curve corresponding to the SENS3 sensor forms approximately a straight line of negative slope.

[0080] The fact that the amplitudes of the signals generated by sensors SENS2 and SENS3, expressed as a function of the amplitude of the signal generated by sensor SENSi, form essentially straight lines is representative of the fact that the ratios of the amplitudes of the signals generated by sensors SENS2 and SENS3 to the amplitude of the signal generated by sensor SENSi are essentially constant. This characteristic is due to the fact that the pressure application zones on the ring remain stationary during the application of pressure.

[0081] Also, as illustrated in (B) of figures 5, 7 and 6, the maximum amplitude among the signals generated by the three sensors is in the signal generated by the sensor at the level of which one of the user's fingers is located while tightening, indicating that this location of the ring has a greater deformation than those of the locations of the other two sensors.

[0082] A clamping action produces two peaks in absolute value in the signals generated by the sensors: a first peak caused by the application of clamping pressure to the ring, and a second peak due to the release of this pressure, identified respectively by Maxl and Max2 in (B) of [Fig.5] for the signal SI. The first peak and the second peak have opposite signs.

[0083] The analysis of curves such as those in figures 5, 6 and 7 makes it possible to trace back to the occurrence of a clamping action as well as to a characterization of this clamping action, a characterization which is a function of the areas of application of the clamping forces.

[0084] For example, a tightening action without significant displacement of the pressure application areas can be considered to have been applied to the ring if a criterion is met, according to which the ratio between the amplitudes of two of the signals is constant to within ±20% of the average value of the ratio during the duration of the action. The percentage can be adjusted by the user. Detecting such an action eliminates the possibility that an action involving significant displacement of the pressure areas on the ring, such as rotation or sliding, was applied. In other words, meeting this criterion implies that a pressure action with substantially constant localization was applied to the ring by a user.To improve the reliability of the application of the criterion, it can be applied only to signal amplitude values ​​exceeding a certain level, in order to avoid the effect of relative noise which becomes very important for small amplitude values ​​and / or adjust the percentage.

[0085] Thus, it is important to note that an analysis of the ratios between the signals generated by the different sensors makes it possible to characterize the clamping action according to a criterion linked to the location of the fingers applying the clamp, not only at the level of a particular sensor, but also at an arbitrary position varying continuously between two sensors. The straight lines obtained by clamping actions gradually shifting from the situation in [Fig. 5] to that in [Fig. 6] would show a corresponding continuous variation in the slopes of the curves. To each slope or group of slopes, and therefore to each ratio of amplitudes of signals generated by two sensors, it is possible to associate a particular location of the action exerted on the ring and to associate to this location a particular command of the external device.

[0086] Double clamping

[0087] Double clamping is a variant of the clamping action described above, in which the clamping action is repeated within a predefined time interval, such as the double-click of a computer mouse.

[0088] This action is detected by counting, for each sensor, the number of maxima occurring during the predefined time interval. Figure 8 illustrates in (A), (B), and (C) the signals S (in mV) generated by the sensors in response to double-tightening actions at sensors SENS1, SENS2, and SENS3, respectively, expressed as a function of time T (in s). The amplitude maxima (in absolute value) clearly show four maxima identified as Max1 to Max4 in (A) of Figure 8 for the signal SL. Thus, the occurrence of a double-tightening action can be associated with the detection of four absolute maxima in the signal generated by a sensor over a determined time interval, preferably on the order of a second or less.

[0089] Long tightening

[0090] A long clamping differs from a clamping that can be described as short, such as those illustrated by figures 5 to 7, in that the clamping is maintained for a certain duration exceeding a predetermined threshold value of duration THR4.

[0091] During a tightening action, the signals generated by the sensors each include a first maximum Maxl in the form of a peak at the beginning of the tightening and a second maximum Max2 of opposite sign to Maxl in the form of a peak with the opposite orientation when the tightening is released. An event is classified as a long tightening when two maxima are detected, each exceeding a predetermined threshold level, and separated by a duration exceeding the predetermined threshold value THR4, as illustrated in B) of [Fig. 9].

[0092] The profile of the curves in B) is explained by the fact that the voltage generated by a piezoelectric sensor will gradually return to zero after application of the deformation, even without the sensor returning to its initial physical state, according to a characteristic time depending on the sensor itself and the acquisition system, i.e. about 0.2 s for the system which generated the signals represented here.

[0093] Rotation - Method 1

[0094] The action of rotating the ring between two fingers while simultaneously applying pressure with those same fingers is referred to as "rotation." This action by the user results in a deformation of the ring, which moves with the rotation. It is this rotation of the ring that allows the transition from configuration (B) to configuration (C) in [Fig. 1]. The sensors can characterize this deformation and its movement, and therefore the rotation imposed on the ring, as described below.

[0095] Figure 10 shows graphs representing SI, S2 and S3 signals (in mV) experimentally generated by the SENSi, SENS2 and SENS3 piezoelectric sensors. of the ring of [Fig.1], respectively, as a function of time T (in s), in (A) for a rotation Rot in one direction from sensor SENS1 to sensor SENS2 then sensor SENS3 (direction 1-2-3) and in (B) for a rotation in the opposite direction from sensor SENS3 to sensor SENS2 then sensor SENS1 (direction 3-2-1), by rotating the ring between two fingers.

[0096] It is observed that the sensor signals oscillate in an approximately sinusoidal pattern. The maxima of the oscillations, which correspond to maxima of the deformations at the three sensors, appear in an order determined by the direction of rotation. This direction can therefore be deduced from the analysis of the signals generated by the sensors by finding the maxima and determining their order of appearance. Thus, it is possible to characterize the rotation in terms of direction, angular amplitude, and speed.

[0097] Rotation - Method 2

[0098] The first method for characterizing a ring rotation is based on the order in which maxima appear in the deformation amplitude. A second method, based on the same signals generated by the sensors, can be considered.

[0099] Fig. 11 shows in A) and B) graphs in which the signals S (in mV) generated by the sensors SENS2 and SENS3 are expressed as a function of the signal SI (in mV) generated by the sensor SENSi, forming two distinct curves in the plane (Si, S) defined by the signal SI and one or the other of the signals S2 and S3. In these two graphs, the progress of the curves over time is followed by moving along them in the directions indicated by the arrows.

[0100] With regard to the graph in A), in a ZSq-Start zone of the graph corresponding to the beginning of the application of the clamping force using the two fingers of [Fig. 1], it can be observed that the two curves move away from the origin of the graph along straight lines until they exceed a threshold level Thr represented by a circle centered on the origin of the graph. The ratios of the signal amplitudes remain essentially constant, due to the fact that the pressure application zones on the ring remain stationary: this is currently a simple clamping action, already described above. The distance of each curve from the origin of the graph is defined by the square root of the sum of the squares of the amplitudes of the signals concerned: either a first pair of signals consisting of the signals from sensors SENS1 and SENS2, or a second pair of signals consisting of the signals from sensors SENS1 and SENS3.The distance from each point on these curves to the origin (0,0) of the graph represents the square root of the sum of the squares of the curve's coordinates at that point.

[0101] In a second step, the ring is rolled between the two fingers, the amplitudes of the remaining signal pairs such that the roots of their quadratic sums remain The pressure exceeds the threshold value, if not remains constant. This behavior is representative of the pressure exerted on the ring by a human: it is difficult to maintain constant pressure on the ring while rolling it between two fingers, but it is possible to maintain a certain level of pressure. The rolling is reflected by displacements over time in opposite directions of rotation along the two curves: clockwise for sensor SENS2, and counterclockwise for sensor SENS3, these two directions depending on the direction of rotation imposed on the ring. The ratios between the amplitudes of the signals generated by sensors SENS2 and SENS3 and the amplitude of the signal generated by sensor SENS1 change continuously due to the ongoing movement of the pressure zones applied to the ring. The detection of these changes indicates the occurrence of a rotational action.The magnitude of these changes is representative of the angle of rotation. The curve can be followed, and an angular amplitude of rotation Q between two given instants can be associated with it, either through calibration or ab initio calculations.

[0102] At the end of the rotation, the finger grip is released, the signal amplitudes return to zero, which means that the curves simultaneously return to the perimeter defined by the threshold level Thr and then fall back to the origin point of the graph, at the levels of the ZSq-End2 and ZSq-End3 grip release zones, for the curves resulting from the signals generated by the Sens2 and Sens3 sensors, respectively. At the moment of grip release, the rotation is stopped, the pressure application points are fixed, and the curves form straight lines, as in the case of a grip described above using Figures 5 to 7.

[0103] Analysis of the graph in A) of [Fig. 11], whether one considers a single curve or both curves, allows us to trace back to the detection of a rotation action of the ring and to the characteristics (angle, duration) of this rotation by correspondence between the points of crossing the threshold level by these curves at the beginning and at the end of the rotation action and a rotation of the ring, correspondence determined by simulation calculations or calibrations of the ring.

[0104] In practice, it may be advantageous to start an analysis of the curve as soon as the Thr threshold level is reached, analyze the curve continuously, generate a rotation detection signal each time the rotation angle exceeds one of a series of thresholds (for example spaced at intervals of 10° or any other predetermined value), and stop the analysis when the curves fall back below the Thr threshold.

[0105] This is illustrated in [Fig. 1 1] in B), with the tracking of the curve representing the signal S2 expressed as a function of the signal SI, signals respectively generated by the sensors Sens2 and Sens1. The curve representing the signal S2 exits the display circle of the threshold Thr at a point A, rotates clockwise around the origin point of the graph while remaining outside the circle, and then crosses it at a Point B. Points A and B are separated angularly by a total rotation angle Qtot. During rotation, the increase in the rotation angle exceeded several thresholds indicated by the values ​​Qi and Q2.

[0106] Tap your finger

[0107] Tapping the finger wearing the ring, preferably on a hard surface such as a table, generates a signal with a higher frequency content than squeezing or rotating the ring. Figure 12 illustrates the S1, S2, and S3 signals detected when the finger wearing the ring is tapped. The frequency components of the signals generated during a finger tap thus make it possible to distinguish this action from squeezing or rotating the ring.

[0108] A method for detecting a tap of the finger wearing the ring may include, as a first step, summing the signals generated by the sensors during an event to obtain a sum signal. A high-pass filter is applied to the sum signal, and then a first RMS value (RmsH) of this filtered sum signal is calculated. A low-pass filter is applied to the same sum signal, and then a second RMS value (RmsL) of this filtered sum signal is calculated. The ratio of these two RMS values ​​is then compared to a predetermined threshold value (THRi). The cutoff frequencies of the applied filters may be, for example, 10 Hz. If the RMSH / RMSl ratio is greater than or equal to the threshold value (THRi), then the event is classified as a tap. If the RMSH / RMSL ratio is less than the threshold value (THRi), then the event is classified as a squeeze. The sum of the signals may be a weighted sum, with each signal associated with a given weighting coefficient.It is therefore possible to choose the coefficients in order to select the sensor(s) used for detection. An effective value can be defined as the square root of the average of the squares of the signal value over a period of time.

[0109] Tap the ring

[0110] The procedure used for finger tapping can be applied to the ring when it is tapped directly on a surface, preferably a hard one, such as a table. The difference is that the signals generated by the sensors have a higher content of high-frequency components than when only the finger wearing the ring is tapped on the hard surface. For example, the waveforms of the S1, S2, and S3 signals in [Fig. 13], generated during the direct tapping of the ring on a table, can be compared to those in [Fig. 12]. Thus, the RMSH / RMSL ratio can then be compared to a threshold value THR2, preferably greater than THRi. If the RMSH / RMSL ratio is greater than or equal to the threshold value THR2, then the event is classified as a ring tap.

[0111] Tap on a sensor

[0112] Tapping a sensor is an action that consists of directly tapping the ring at the location of one of the sensors with a finger. The difference with the pressure is that the force is applied on only one side of the ring, and not on both sides. In the case of the configuration illustrated by [Fig.1], the sensors are tapped directly and the measured amplitudes of the signals S (in mV) generated in response by the sensors are illustrated by means of the graphs in [Fig.1 1], with (A), (B) and (C) the results of measurements for taps on the sensors SENS1, SENS2 and SENS3, respectively.

[0113] For each of the situations (A), (B) and (C), it is observed that the maximum amplitude among all the signals generated by the sensors is that corresponding to the sensor at the level of which the tap is made, and that it corresponds to the maximum amplitude of a peak.

[0114] Thus, a tap event on a given sensor can be identified by identifying the sensor whose generated signal has a peak with the highest amplitude, calculating the ratio of this amplitude to the maximum amplitudes of each of the other sensors, and, if these ratios are all greater than a threshold value THR3, classifying the event as a tap at the sensor that generated the signal with the peak with the highest amplitude, therefore the maximum amplitude.

[0115] Example of an algorithm

[0116] As illustrated above, several types of events applied to the ring can be detected by analyzing the signals from the sensors mounted on it.

[0117] Figures 15 to 18 illustrate a method of using a ring R equipped with at least two sensors SENSi and SENS2, according to an algorithm allowing the detection of several types of events each characterized by the signals generated by the sensors following an action by the user on the ring.

[0118] During a user action on the ring, two digital signals SI and S2 are generated by the two sensors SENSi and SENS2, respectively, and the analog-to-digital converter CONV.

[0119] A first calculation block Bli is designed to discriminate background noise or accidental or purposeless manipulations from a deliberate action by the user. In the first calculation block Blb, the CALC computer performs the quadratic summation of the amplitudes of the signals SI and S2 during a summation operation B1m0. During a test operation B1m5, the computer determines whether the quadratic summation Q of the signal amplitudes exceeds a predetermined threshold value Thr, indicating that an action has been deliberately performed on the ring. This test operation has a function of detecting an event measured by the ring's sensors.In response to this determination, in the case where the sum exceeds the threshold value, an action detection signal SAct is generated and, in response to this signal, a second calculation block Bl2 is implemented and the signals SI and S2 are recorded in a computer memory MEM in functional communication with the computer Cale during. of operation Bli_20. The recorded signals will be used in subsequent operations. Recording is stopped when the quadratic sum falls below the threshold value THR.

[0120] More generally, the amplitude of a signal representing a sum of unaveraged signals generated by the sensors, or the amplitude of a single signal, averaged or unaveraged, representing a signal generated by a single sensor, could be used as the amplitude of the Q signal and compared to the threshold value to determine the occurrence of a deliberate action. In all cases, the amplitude of a signal or a combination of signals, processed or unprocessed, representing a deformation of the ring, is compared to a predefined threshold, and it is determined that a deliberate action has been exerted on the ring when this amplitude exceeds this predefined threshold, such as the threshold level Thr shown in [Fig. 11]. Averaging over a combination (in particular, a sum) of several signals representing signals generated by the sensors provides greater reliability in this determination.

[0121] Alternatively, in order to discriminate background noise or accidental or purposeless manipulations from a deliberate action by the user, the BImo test operation could focus on a variance in the amplitudes of the signals emitted by the sensors. This variance can, for example, be calculated over a rolling period of a signal or of the weighted or unweighted sum of several signals generated by the sensors, and can be considered an event detection signal when it exceeds a predetermined threshold, set, for example, by a user: the variance of the signals becomes indeed greater when the user performs an action on the ring.

[0122] The test step B1m5 thus has the function of detecting an exceedance of a threshold by a quantity representative of an amplitude of a signal or a combination of signals each representative of a deformation of the annular element and generated by one or more of the deformation sensors mounted on the annular element in response to an action of the user, whether the quantity in question is derived directly from the amplitudes of the signal(s) considered, from a variance of this or these signals, or is representative of any other information derived from the signal(s) considered.

[0123] The Bli block is advantageous from the standpoint of human-machine interface autonomy: except when an event exceeding a certain threshold level is detected, only a portion of the ACQ acquisition module associated with the Bli block requires a power supply, which significantly limits the overall power consumption of the device. Indeed, a comparator, an electronic device consuming very little energy, can be sufficient to implement the BU block, particularly when piezoelectric sensors are used, as the voltages they generate are sufficient to operate the comparator without requiring amplification.

[0124] The second calculation block, Bl2, performs an initial analysis of the SI and S2 signals to detect whether or not the user is rotating the ring and, if so, to characterize this rotation. When the Bl2 block is implemented, the CALC computer performs the operations described below. In preliminary steps, (i) a counter in the CALC computer initializes a rotation increment count variable n to 0 at step B12.i0, and the CALC computer determines and assigns to a rotation angle variable Qod the exit angle of the circle of radius Thr in the (SI, S2) plane by the S2 signal, as determined according to method 2 for characterizing a rotation based on the SI and S2 signals, at step Bl215. For illustration, see area ZSq-Start in A) of [Fig. 11]. In the graph in B) of the [Fig.11], this exit angle corresponds to the orientation of the line passing through the origin of the graph and the point A located on the circle of radius Thr. .

[0125] A test operation Bl2 20 ensures that as long as the squared sum of the signals remains above the threshold Thr, as indicated by the filled test condition indicator Y, the following computation loop is continuously executed by the computer. A current rotation angle Q is calculated based on the signals SI and S2 according to method 2 during a Bl2 25 operation. A difference Q-Qo is calculated in a Bl2 30 operation, and the result of this difference is compared during two test operations Bl2 35 and Bl2 45 to a positive angular threshold value ThrAng and its opposite -ThrAng, respectively. If the test operation Bl2 35 returns a positive result, indicated by Y in the figure, then an event determination signal ROT- is generated, representing that i) the ring has been rotated by an angle defined by the value of ThrAng, and ii) this rotation is in a direction defined as negative.Conversely, if the Bl2 45 test operation returns a positive result, indicated by Y in the figure, then a ROT+ event determination signal is generated, representing that i) there has been a rotation of the ring by an angle defined by the value of ThrAng, and ii) this rotation is in a direction defined as positive.

[0126] In response to positive results from test operations Bl2 35 and Bl245, the rotation increment count variable n is incremented by 1 during an operation Bl2 55, and the current rotation angle Q is assigned to the rotation angle variable Q. The count value n thus indicates the number of times the ring has been rotated by a value ThrAng during the rotation being analyzed. By repeating these operations, rotations can be tracked in both directions, according to amplitude increments defined by the value of ThrAng.

[0127] This algorithm implements method 2 for characterizing a rotation of the ring, but method 1 could be applied, or any other suitable method.

[0128] If the test operation Bl2 2o returns a result N, indicating that the quadratic sum of the signals SI and S2 has fallen below the value Thr, then another test operation Bl270 is performed to check if the count value n is 0, indicating that the analyzed event is not a rotation. If so, then a rotation-absence detection signal S NoRot is generated and, in response, a third computation block Bl3 is implemented during a step Bl2 75.

[0129] Alternatively, the Bl2 70 test operation could be implemented independently of the count value n, by implementing the test principle described in the "Tightening" section. Thus, the Bl2 70 test operation could consist of testing whether a ratio between the SI and S2 signals is substantially constant over the duration of the analyzed event, i.e., within an interval defined by XX% around the average value of the ratio over the duration of the recorded event, XX% representing a percentage of the average value defined by the user, for example 20%, which constitutes a value allowing for a relevant discrimination of the constancy of the ratio.

[0130] The third computing block, Bl3, illustrated in [Fig. 17], analyzes the signals generated by the sensors once it has been determined that the event is not a rotation. More specifically, block Bl3 discriminates the type of action among ring tightening, finger tapping, and ring tapping, and characterizes the tightening actions. To this end, the computer implements the operations of block Bl3, the principles of which are explained in the Tightening, Finger Tapping, and Ring Tapping sections described above.

[0131] First, the digitized signal SI is filtered in parallel using two filtering operations Bl310 and Bl315 employing a high-pass filter and a low-pass filter, respectively, to obtain two filtered signals. Each of the two signals filtered by the filtering operations Bl310 and Bl215 is averaged during averaging operations Bl315 and Bl315 to obtain the RMSH and RMSH means of the two averaged filtered signals, respectively. The averaging period can be selected by the user according to their preferences.

[0132] According to the principle explained above in the sections "Finger Tap" and "Ring Tap", a first test operation Bl3 35 checks whether the value of the RMSH / RMSl ratio is greater than a high threshold value ThrH. If a positive response, indicated by Y in the figure, is returned, then a detection signal Hit(R) is generated, representing that the event was caused by a ring tap action on a rigid surface.

[0133] If a negative response to test operation Bl3 35, indicated by N in the figure, is returned, then test operation BL5.40 is implemented, checking whether the RMSH / RMSL ratio value is greater than a low threshold value ThrL, with ThrL < ThrH.

[0134] If a positive response, indicated by Y in the figure, is returned, then a Hit(F) detection signal is generated, representative of the fact that the event was caused by a finger tap action (F3) bringing the ring to a rigid surface.

[0135] If a negative response to the test operation Bl3.40, indicated by N in the figure, is returned, then it is determined that the event was caused by a clamping action, and a fourth computing block Bl4 is implemented during an operation Bl3 45.

[0136] Operations Bl340 to Bl340 together constitute one B13 FA operation The analysis of the frequency content of the signals emitted by the sensors is based on which the actions of finger tapping (Hit(F)) and ring tapping (Hit(R)) are detected, as well as whether the user's action is a tightening action. The latter is characterized in greater detail by block Bl4, described below. The principle employed is that the energy of a signal or a sum of signals is distributed more predominantly in the higher frequencies for the action Hit(R) than for the action Hit(F), and more predominantly in the lower frequencies for ring tightening actions than for the action Hit(F). Block Bl3 in [Fig. 13] illustrates a specific implementation of this principle, but other implementations can be considered by those skilled in the art.

[0137] Fundamentally, this involves analyzing the energy distribution of the detected signals according to frequencies. For example, it would be possible to perform a Fourier transform on the signals and analyze the energy distribution in the frequency domain, for instance by comparing the energy contained in the signals for frequencies above 10 Hz with the energy contained in the same signals for frequencies below 10 Hz.

[0138] The fourth processing block, Bl4, illustrated in [Fig. 18], analyzes the signals generated by the sensors when it has been determined that the event detected by block B1 is neither a rotation nor either a ring tap or a finger tap, as determined at the levels of blocks Bl2 and Bl3. More specifically, block Bl4 characterizes the type of tightening applied to the ring by the user: short tightening, long tightening, double tightening, and the location of the tightening. To this end, the processor performs the operations of block Bl4 described in the Tightening, Finger Tap, and Ring Tap sections described above.

[0139] Operations Bl4_i0, Bl4 X5, and BU20 of block Bl4 allow for the spatial characterization of the event being analyzed. Operation Bl4 xo consists of calculating the ratio of the SI and S2 signals, then averaging this ratio during a BU20 averaging operation over the entire duration of the detected event. This average is compared to a calibration table prepared in advance, establishing a correspondence between Averaged ratio values ​​and the location of a clamping force applied to the ring are recorded. The calibration table can be stored in MEM memory. Based on this comparison, a Loc signal representing the location of the event being analyzed is generated.

[0140] Figure 16 illustrates the localization of pressure (squeezing, tapping) applied by a finger Fl to a ring R equipped with sensors SENS1 and SENS2. A table prepared in advance by calibrating the ring can indicate a correspondence between the ratio of the amplitudes of the signals generated respectively by sensors SENS1 and SENS2 and a localization marked by a radius rLocai angularly offset from a reference radius rref. The same table, or a similar table taking into account the two diametrically opposed contact areas present during a squeeze between two fingers, can be used to locate the beginning and end of the squeeze illustrated by Figure 11 and thus evaluate the angular amplitude of the rotation applied to the ring during a rotational action.In general, any action (tightening, rotation, tapping) can be associated with a localization signal representative of a local location of the action considered, based on a ratio of the amplitudes of two signals generated simultaneously by two sensors located on two distinct radii of the ring.

[0141] Operations BI4.30 to Bl4_50 of block BI4 allow determination of the type of clamping applied to the ring which caused the generation of signals SI and S2.

[0142] The BI4î0 operation consists of detecting the number of peaks, that is, the number of amplitude maxima, in absolute value, for each of the signals SI and S2, and averaging the number of peaks detected. Alternatively, one can simply count the number of peaks detected for a signal. However, averaging over several signals makes the detection more robust.

[0143] Based on operation Bl4 30, test operation Bl4 35 returns a positive response when the number of detected peaks is close to 4, for example, within a range of 3.5 to 4.5 encompassing four to account for the averaging effect, as indicated by Y in the figure. In response to a positive response to test operation Bl4 35, a detection signal D.Sq is generated, representative of a double clamping action (2 peaks per clamping action, therefore 4 peaks for a double clamping action, as explained in the "Double Clamping" section above).

[0144] Based on operation Bl4 30, test operation Bl4 40 returns a positive response when the number of detected peaks is 2, as indicated by Y in the figure. In response to this detection, the time interval AT separating the two detected peaks is determined during operation Bl4 45. During a test operation Bl4 50, the time interval AT is compared to the predetermined duration threshold value THR4 as explained in the "Long Clamping" section above.

[0145] If it is determined that AT is greater than THR4, as indicated by Y in the figure, then a signal L.Sq representative of a long clamping action is generated.

[0146] If it is determined that AT is not greater than THR4, as indicated by N in the figure, then a signal S.Sq representative of a short clamping action, or clamping, is generated.

[0147] Blocks B11 and B12 directly process the SI and S2 signals generated by the sensors. Blocks B13 and B14 process the version of these signals recorded in MEM memory during step BI1.20.

[0148] One advantage of this algorithm is that it consumes only a minimum of energy, the parts of the ACQ acquisition module associated with blocks Bl2 and Bl3 of the algorithm being activated only when it has been determined that it is necessary to use their respective functionalities.

[0149] When averaging operations are mentioned in this description, it will be understood that, unless otherwise indicated, this refers to averaging over time, over a period that can be chosen by the user or the manufacturer of the human-machine interface according to the desired behavior of that interface. However, these periods may be on the order of a few tenths of a second.

[0150] Also, when we talk about a signal generated by the sensors, it may be a converted or processed signal and not only one directly from the sensor, as long as it can be considered representative of a deformation applied to the ring, that is to say, as being able to be used to characterize this deformation.

[0151] Of course, a person skilled in the art will be able to develop similar algorithms to enable the user to benefit from all the types of action described in this description.

[0152] In addition, it is entirely possible to detect other actions than those described above, such as a three-finger press, a finger slide on the ring without rotating it ("swipe" in English terminology), a finger flexion, hand extension, fist clenching, rotation around the finger without moving the pressure areas applied to the ring, etc.

[0153] Furthermore, a person skilled in the art would understand that it is possible to implement other algorithms than those described here to exploit the signals generated by the sensors, including an approach called artificial intelligence, allowing the detected signals to be classified into different predefined categories by carrying out machine learning based on a database of signals measured during realistic actions by a user wearing the ring.

[0154] With regard to the structure of the sensor assembly, the invention is not limited to the examples mentioned above, and the annular element and the sensors can be implemented in different ways, as illustrated by Figures 1, 3, and 19 as described below.

[0155] Thus, the sensor assembly can include an open or closed annular element ANN formed from a block as illustrated in A) of [Fig. 19], an annular element formed from two coaxial elements ANNi / 2c and ANN2 / 2C as illustrated in B) of [Fig. 19], or formed from two angularly complementary parts ANNi / 2A and ANN2 / 2A connected by assembly elements AE, preferably rigidly to each other so as to transmit a deformation applied to one element to the other, as illustrated in C) of [Fig. 19].

[0156] The sensors can be mounted on the same surface, either internal or external to the ring, as illustrated in Figures 1 and 3, or they can be mounted on different surfaces of the ring. Figure 19 illustrates in A) a configuration where the SENS1 and SENS3 sensors are mounted on an external surface Sext of the annular element and the SENS2 sensor on an internal surface Sint of this annular element; in B) a configuration where the SENS1 and SENS3 sensors are mounted on an external surface of the annular element and the SENS2 sensor is positioned between a first coaxial element ANN1 / 2C and a second coaxial element ANN2 / 2C of the annular element; in D) a configuration similar to the configuration illustrated in A), except that the sensors are mounted in recesses or notches formed on the annular element.Placing the sensors in recesses can protect them from external damage when they are directly accessible from the outside, or make the ring more comfortable for the user to wear when they are located on the inner surface in contact with the skin.

[0157] The sensors can also be mounted on parts of the annular element other than its outer or inner surfaces. Figure 19 illustrates in E a configuration where the sensors are mounted on a surface St of the ring's edge, so as to be positioned along a plane intersecting the ring's longitudinal axis.

[0158] The sensors are mounted on the annular element so as to be fixed to its deformations and thus generate signals representative of these deformations. They can be glued to a surface of the annular element, crimped between two elements of the annular element, or integrated in any other way considered suitable to those skilled in the art.

[0159] Any combination of the sensor implementations illustrated in Figures 1, 3 and 19 is acceptable and falls within the scope of the invention described herein.

[0160] The invention is not limited to the embodiment described above and alternative embodiments may be made without departing from the scope of the invention as defined by the claims.

Claims

Claims

1. Sensor assembly (CAPT) comprising an annular element (ANN) of substantially cylindrical shape and at least two deformation sensors (SENSi, SENS2, SENS3) mounted on the annular element at levels of at least two radii (rl, r2, r3) distinct from the latter, respectively, so as to be sensitive to a deformation of the annular element.

2. Sensor assembly (CAPT) according to claim 1, in which the at least two distinct rays (rl, r2, r3) are angularly spaced apart from each other by an angle of between 20° and 160°.

3. Sensor assembly (CAPT) according to claim 1 or 2 in which the at least two deformation sensors (SENSi, SENS2, SENS3) are piezoelectric type sensors.

4. Human-machine interface (R) comprising the sensor assembly (CAPT) according to any one of claims 1 to 3, further comprising an acquisition module (ACQ) configured to generate a detection signal (ROT-, ROT+, Loc, S.Sq, L.Sq, D.Sq, Hit(F), Hit(R)) in response to a deformation of the annular element on the basis of signals (SI, S2, S3) emitted by the at least two deformation sensors (SENSi, SENS2, SENS 3), the human-machine interface being configured so as to generate control signals for an apparatus (APP) external to the human-machine interface (R) in response to the detection signal.

5. A human-machine interface according to claim 4, wherein the detection signal is one of a signal (S.Sq) for detecting a short ring clamping action, a signal (L.Sq) for detecting a long ring clamping action, a signal (D.Sq) for detecting a double ring clamping action, a signal (Loc) representative of a location (Local) of any one of the preceding actions, a signal for detecting a finger tapping action (Hit(F)), a signal for detecting a ring tapping action (Hit(R)), a signal (ROT-) for detecting a rotation action in a negative direction, and a signal (ROT+) for detecting a rotation action in a positive direction.

6. Human-machine interface according to any one of claims 4 to 5, in which the acquisition module is configured to: - detect (B1m5) an exceeding (ZSq-Start) of a threshold (Thr) by a quantity (Q) representative of an amplitude of a signal or of a com- combination of signals (SI, S2) each representative of a deformation of the annular element (ANN) and generated by one or more sensors of the at least two deformation sensors (SENSi, SENS2), and - in response to this detection, generating a signal (SAct) representative of the occurrence of an action applied to the annular element (ANN).

7. Human-machine interface according to claim 6, configured to keep awake only a first part of the acquisition module (ACQ) associated with the detection (B1m5) and to activate second parts of the acquisition module only when it is determined that respective activations of these second parts are necessary for an analysis of the signals (SI, S2).

8. Human-machine interface according to any one of claims 6 to 7, wherein the acquisition module is configured to: - detect (Bl2 35, Bl245) a rotation (Rot) of the ring on the basis of the first signal (SI) and the second signal (S2); and - in response to the detection step, generate a signal (ROT-, ROT+) representative of the occurrence of a rotation of the annular element (ANN).

9. A human-machine interface according to any one of claims 4 to 6, wherein the acquisition module is further configured to: - based on at least two of the signals, generate (Bl2 7o) a signal (S No.Rot) representative of the fact that a pressure action (F) of substantially constant location has been applied to the ring by a user; and - in response to this detection, generate one of a signal (S.Sq) for detecting a short ring clamping action, a signal (L.Sq) for detecting a long ring clamping action, a signal (D.Sq) for detecting a double ring clamping action, a signal (Loc) representative of a location (Local) of any one of the three preceding actions, a signal for detecting a finger tapping action (Hit(F)), and a signal for detecting a ring tapping action (Hit(R)).

10. Human-machine interface according to any one of claims 4 to 9, in which the acquisition module is configured to: implement an operation (B13FA) of analyzing the frequency content of the signals; and in response to the operation (B13 fa) of analyzing the frequency content of the signals, generate one of a signal for detecting a tapping action of a finger (Hit(F)) and a signal for detecting a tapping action of the ring (Hit(R)).

11. Human-machine interface according to any one of claims 4 to 10, wherein the acquisition module is configured to: detect (Bl4 30) peaks (Maxl, Max2, Max3, Max4) in an amplitude of at least one of the signals (SI, S2); and in response to the number of peaks detected, generate (BI435, BI4M) one of a signal (S.Sq) for detecting a short clamping action of the ring, a signal (L.Sq) for detecting a long clamping action of the ring, a signal (D.Sq) for detecting a double clamping action of the ring.

12. Human-machine interface according to any one of claims 1 to 11, further comprising a wireless transmission module (COM) configured to transmit signals generated by the acquisition module (ACQ) to the external apparatus (APP) and a power supply source (BAT) for the wireless transmission module (COM) and the acquisition module (ACQ).

13. Human-machine interface according to any one of claims 4 to 12, further comprising a feedback device (FB) configured to signal to a user a generation of a detection signal (ROT-, ROT+, Hit(R), Hit(R), Loc, S.Sq, L.Sq, D.Sq) by the acquisition module (ACQ).

14. Human-machine interface according to any one of claims 4 to 13, configured to be threaded onto a part (F3) of a user or a rod (RD) of a control device of the external apparatus.

15. Kit comprising a human-machine interface according to any one of claims 4 to 14 as well as the apparatus (APP).

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