FR3089032A1 - METHOD AND APPARATUS FOR CALIBRATION OF A HAPTIC WALL ASSOCIATED WITH A FORCE SENSOR - Google Patents

Abstract

METHOD AND APPARATUS FOR CALIBRATING A HAPTIC WALL ASSOCIATED WITH A FORCE SENSOR An apparatus (AC) calibrates a haptic wall (PH) to be fixed on a sensor (CF), and comprises: a plate (PC) provided with an element in relief (ER) and fixed on the sensor (CF) or the haptic wall (PH) fixed on the sensor (CF) in the first and second stages, a recorder (ES) recording first, second and third signals delivered by the sensor (CF) when a predefined force is applied with a finger (DU) on the plate (PC) or the haptic wall (PH) and when relative movements of the finger (DU) are carried out during the first, second and third stages , and a computer (CA) determining a transfer function between the first and second signals, and applying its inverse to the third signals to determine fourth signals representing the haptic effect created by the haptic wall (PH) and felt by the finger ( OF).

Description

Description

Title of the invention: METHOD AND APPARATUS FOR CALIBRATION OF A HAPTIC WALL ASSOCIATED WITH A FORCE SENSOR

Technical field [0001] The invention relates to haptic walls intended to be fixed to at least one sensor, and more precisely the calibration of such haptic walls.

PRIOR ART Certain pieces of equipment or apparatus include at least one human / machine interface comprising at least one touch wall which, when contacted by the end of a user's finger, can, for example, induce or trigger the generation of a signal intended to control a function. This is for example the case of certain control members or of certain devices offering an image display function (such as for example and without limitation communication equipment (smart phones (or “smartphones”) or electronic tablets), game consoles (possibly communicating), or terminals or screens (possibly computer).

Sometimes, the touch screen of these devices provides a haptic function which signals to the user, via the sense of touch of his finger which ensures contact, that the latter has been detected and therefore that it will be used to control an associated function, or which more simply makes it possible to provide the user, via his contact finger, with a feeling of touch (for example of texture, border, or button, or transient effect). Such a tactile wall is then often called a haptic wall (or surface).

The haptic function is generally provided by vibration means which are coupled to the haptic wall and which are responsible for locally vibrating the latter when the contact has been detected. The haptic function can also be achieved by electro-adhesion or any other technology.

[0005] The detection of a finger contact (and its direction, direction and intensity) requires the coupling of one or more force sensors (generally with strain gauges) under the haptic wall. It will be understood that the sensor (s) are here responsible for measuring the force (s) caused by the interaction of the finger with the haptic wall.

Without prior calibration (or characterization), the force measurements made by the sensor (s) are biased by resonance and oscillation effects of the haptic wall / sensor (s) assembly, which vary depending on the mass, composition and shape of the haptic wall.

[0008] [0009] [0010] [0011]

Different methods of calibration (or characterization) of a haptic wall and its associated sensor (s) have been proposed. They determine for example the impulse response to an impact, or the response to white noise, or the response to a frequency sweep (or “chirp” in English), or the response to a step.

These known calibration (or characterization) methods allow a good description of each isolated haptic wall / sensor (s) assembly. However, when you want to measure the consequences of a haptic effect, you have to come and explore the haptic wall with the finger of a user. However, when the finger presses and moves on the haptic wall, this induces a change in the mass and damping of the haptic wall / sensor (s) assembly, and therefore modifies the dynamics of this assembly. Consequently, the calibration (or characterization) carried out with these methods cannot be used to calibrate (or characterize) the consequences of a haptic effect.

The invention therefore aims in particular to improve the situation.

Statement of the invention

It notably proposes for this purpose a method intended to calibrate a haptic wall, itself intended to be fixed on at least one sensor delivering signals representative of at least one force exerted on it. This process is characterized by the fact that it includes:

a first step in which a plate provided with a relief element is fixed on the sensor, then a predefined force is applied to the plate with a finger of a user, while carrying out predefined relative movements of the finger relative to the plate with the finger passing through the element in relief and simultaneously recording the first signals delivered by the sensor,

- a second step in which the sensor plate is removed, then the haptic wall is fixed on the sensor and the plate on the haptic wall, then the predefined force is applied to the plate with the finger, while carrying out the relative movements of the finger with respect to the plate with the finger passing through the element in relief and simultaneously recording second signals delivered by the sensor, and a transfer function between these first and second signals is determined, and

a third step in which the plate is removed from the haptic wall and then the predefined force is applied to the haptic wall with the finger, while making the relative movements of the finger relative to the haptic wall and simultaneously recording third signals delivered by the sensor, then the inverse of the determined transfer function is applied to the third recorded signals in order to determine fourth signals representative of a haptic effect created by the haptic wall and felt by the finger.

[0012] [0014] [0015] [0016]

Thus, one can take into account the changes in dynamics caused by the fixation of the haptic wall on the sensor (s) and by the contact of the finger.

The calibration method according to the invention may include other characteristics which can be taken separately or in combination, and in particular:

- In its first and second stages, it is possible to use a plate provided with an element in relief which is chosen from a groove, a rib, a hole, a boss and a texture;

- In its first and second stages, it is possible to use a plate provided in a central position with the element in relief;

- in its first, second and third stages, relative movements of the finger can be carried out in two opposite directions in a single chosen direction and at a predefined speed;

in its first, second and third stages, a six-axis type sensor can be used and delivering signals which are representative of first and second forces exerted on it in respectively normal and tangential directions;

- In its first, second and third stages, the sensor can be fixedly secured on a fixed support and the finger can be moved relative to this support;

- As a variant, in its first, second and third stages, the sensor can be fixedly secured to a support and the support can be moved relative to the finger.

The invention also provides a calibration device intended to calibrate a haptic wall itself intended to be fixed on at least one sensor delivering signals which are representative of at least one force exerted on it. This device is characterized by the fact that it includes:

- a support on which the sensor is fixed,

- a plate provided with an element in relief and intended to be fixed on the sensor in a first step then on the haptic wall when the latter is fixed on the sensor in a second step,

a recorder recording, on the one hand, first and second signals delivered by the sensor when a predefined force is applied to the plate with a finger of a user and that predefined relative movements of the finger relative to the plate are performed with the finger passing through the element in relief, respectively during the first and second stages, and, on the other hand, third signals delivered by the sensor when the predefined force is applied to the haptic wall with the finger and that the predefined relative movements of the finger relative to the haptic wall are carried out during a third step in which only the haptic wall is fixed to the sensor, and

- a computer determining a transfer function between the first and second recorded signals, and applying the inverse of this determined transfer function to the third recorded signals in order to determine fourth signals representative of a haptic effect created by the haptic wall and felt by the finger.

The calibration device according to the invention may include other characteristics which can be taken separately or in combination, and in particular:

- Its support can be fixed and in this case the finger is moved relative to the support;

- As a variant, it may comprise displacement means to which its support is fixedly secured and effecting the predefined relative displacements of the support relative to the finger.

Brief Description of the Drawings Other characteristics and advantages of the invention will appear on examining the detailed description below, and the attached drawings, in which:

[Fig.l] illustrates schematically and functionally, in a side view, part of an exemplary embodiment of a calibration device according to the invention, involved in the first step of a calibration process according the invention, [fig.2] schematically and functionally illustrates, in a side view, the calibration apparatus of FIG. 1 in full during the second step of the calibration process, [0022] [fig.3 ] schematically and functionally illustrates, in a side view, a part of the calibration apparatus of FIG. 1, involved in the third step of the calibration process, [0023] [fig.4] schematically illustrates, within a diagram, an example of a time evolution curve (t) of a force (F1) represented by first signals (si) delivered by the sensor of FIG. 1 during the first step of the calibration process, [0024] [ fig.5] schematically illustrates, within a diagram, an example of evolution curve on time (t) of a force (F2) represented by second signals (s2) delivered by the sensor of FIG. 2 during the second step of the calibration process, [0025] [fig.6] schematically illustrates, within of a diagram, an example of a time evolution curve (t) of a force (F3) represented by third signals (s3) delivered by the sensor of FIG. 3 during the third step of the calibration process, [0026 ] [fig.7] schematically illustrates, within a diagram, an example of a time evolution curve (t) of a force (F4) represented by fourth signals (s4), determined by application to the third signals ( s3) of a transfer function (between the first (if) and second (s2) signals), and representative of a haptic effect created by the haptic wall of FIGS. 2 and 3 and felt by a user's finger, and [Fig.8] schematically illustrates an example of an algorithm implementing a calibration method according to the invention.

Description of the embodiments The aim of the invention is in particular to propose a calibration method, and an associated AC calibration apparatus, intended to allow the calibration of assemblies (haptic wall PH / CF sensor (s)).

Within each set (PH / CF), the PH haptic wall is intended to be fixed to at least one CF sensor which is responsible for delivering signals representative of at least one force exerted on it. For example, a haptic wall PH can be fixed to a CF sensor of the six-axis type (or another type of force sensor) and responsible for delivering signals representative of first and second forces exerted on it in respectively normal and tangential directions . Note that the signals delivered by the sensor (s) CF can be analog or digital. The sensors can also be displacement sensors.

For example, the PH haptic wall can be made of glass, or of aluminum, or even of a rigid plastic material such as polycarbonate (or PC) or polymethyl methacrylate (or PMMA).

In what follows, we consider, by way of nonlimiting example, that the assemblies (haptic wall PH / sensor (s) CF) are intended to be part of human / machine interfaces of display screens tactile and haptic. But the invention is not limited to this application. It relates in fact to any type of apparatus or equipment ensuring at least one function controllable by contact with a finger of a user, or forming part of a system ensuring at least one function controllable by contact with a finger of a user, or allowing to provide the user with a feeling of touch (haptically). Thus, the man / machine interface may also, and without limitation, be part of a control member capable of controlling at least one function of a system, or of a device offering a function for displaying images (as example and not limited to communication equipment (smart phone (or smartphone) or electronic tablet), a game console (possibly communicating), or a terminal or screen (possibly computer)), or even a biometric measurement device.

Furthermore, a set (PH haptic wall / CF sensor (s)) to be calibrated is not necessarily intended to be part of a man / machine interface. Thus, it can, for example and without limitation, be part of a support element (handle) or an element of style or comfort.

In addition, it is considered in what follows, by way of nonlimiting example, that the system which is intended to equip the touch and haptic display screen is a motor vehicle, such as for example a car. However, the invention is not limited to this type of system. Indeed, the touch and haptic display screen can be part of any system providing at least one controllable function, and in particular of a vehicle (land, sea (or river), or air), a installation (possibly industrial), of a building, or of electronic equipment (possibly household appliances or such as a smart phone (or “smartphone”) or a communicating tablet).

As mentioned above, the invention provides in particular a calibration method intended to allow the calibration of assemblies [PH haptic wall / CF sensor (s)].

This calibration process can be at least partially implemented by an AC calibration device which comprises for this purpose, as shown without limitation in Figures 1 to 3, an SF support, a PC plate provided with an element in relief ER, an ES recorder and at least one CA computer. The latter (CA) can, for example, comprise at least one digital signal processor (or DSP (“Digital Signal Processor”)), possibly associated with at least one memory.

Note that the CA computer and the ES recorder may possibly be part of a housing ensuring their protection and facilitating their possible transport.

The calibration method according to the invention comprises first 10-20, second 30-50 and third 60-80 steps.

In the first step 10-20 of the calibration process, we begin by temporarily attaching to the CF sensor of a set (PH / CF) to calibrate the PC plate forming part of the AC calibration device.

The CF sensor (s) is (are) temporarily fixed on the support SF of the AC calibration apparatus. This temporary fixing can be done by any type of pressure tightening (clamping jaws, clamping screws, elastics) or by adhesion (adhesive tape, temporary glue), for example.

As indicated above, this PC plate is provided with an element in relief ER which is intended to cause on the end of a finger DU a feeling of touch similar to that of the haptic effect which one wants to calibrate.

The PC plate can, for example, be made of glass. But any other material having a hardness much greater than that of the end of a DU finger of a user can be used. By way of example, this PC plate can have a length of around 100 mm, a width of around 50 mm and a thickness of around 2 mm.

Preferably, the PC plate is provided with its element in relief ER in a central position to optimize the measurements.

Note that one can use a PC plate provided with an element in relief ER which is chosen from a groove, a rib, a hole, a boss and a texture. When the element in relief ER is a groove or a rib, it preferably extends over the entire width of the plate PC in order to have a width greater than the thickness of the finger DU.

In the example illustrated without limitation in Figures 1 and 2, the element in relief ER is a straight groove. For example, this ER groove may have a width of 0.6 mm and a depth of 0.1 mm.

Temporary fixing of the PC plate on the sensor (s) CP can be done by any type of pressure tightening (clamping jaws, clamping screws, elastic) or by adhesion (adhesive tape, temporary glue ), for example.

Once this temporary fixation has been carried out, the first step 10-20 continues with the application of a predefined force PP on the plate PC with a finger DU of a user, while carrying out predefined relative displacements of this finger DU with respect to the plate PC with passage of the finger DU by the element in relief ER and simultaneously recording the first signals if delivered by the sensor CP.

It is important to note that in the foregoing and what follows, the term “relative displacement” means both a displacement of the finger DU with respect to the plate PC (and its support SP), when the latter (PC and SP) are fixed, only a displacement of the plate PC (and its support SP) relative to the finger DU, when the latter (DU) is fixed. It will be understood that during each relative movement the finger DU passes through the element in relief ER, which makes it possible to simulate each time the haptic effect concerned.

We realize here several relative passages of the finger DU by the element in relief ER (and therefore several (N) relative displacements) so that the first signals if recorded result from averaging and are representative of the average force PI exerted when passing through the element in relief ER in the presence of the only PC plate. For example, the number N of relative displacements (and therefore of passages) can be between 1 and (the higher this number, the more precise the average).

For example, one can make relative movements of the DU finger in two opposite directions in a single chosen direction dt and at a predefined speed. In other words, the finger DU makes relative translations by round trip in the direction dt. This direction dt is preferably perpendicular to the element in relief ER in order to best simulate the haptic effect which the haptic wall PH must create and which must be felt by the finger DU.

We schematically illustrated in Figure 4, in a diagram, an example of a time course curve (t) of the average force F1 represented by the first signals if recorded during the first step 10-20. The average force F1 can, for example, be the coefficient of friction (tangential force / normal force), without unit, and can take values ranging between 0 and 1. But it could also be the tangential force in Newtons ( normal force is indeed considered to be approximately constant during a displacement).

It is also important to note that the predefined force FP applied to the plate PC is relative. It can indeed result either from a movement of the DU finger towards and against the PC plate (when the latter (PC) is temporarily fixed on a fixed SF support of the AC calibration apparatus), or of a movement of the support SF with the PC plate towards and against the finger DU which is then fixed. In the first alternative, the AC calibration apparatus must include, in addition, displacement means to which the support SF is fixedly secured and arranged so as to effect the predefined relative displacements of the support SF relative to the finger DU, as well as preferably the initial movement of the support SF towards and against the finger DU. These displacement means can, for example, include three translators responsible for carrying out translations of the support SF in three directions of space (perpendicular to each other).

The recording of the first signals if delivered by the sensor (s) CF is carried out by the ES recorder of the AC calibration device. To this end, the ES recorder can include a storage memory and, as illustrated without limitation, be coupled to the CF sensor (s), for example by a wired link (but it could also be done by waves). As a variant, the CF sensor (s) can be coupled to the CA computer (by wire or wireless), and in this case the CA computer transmits the signals to the ES recorder, to which it is coupled (wired or non-wired).

When the ES recorder is responsible for averaging the signals delivered by the sensor (s) CF, it can for this purpose include at least one digital signal processor (or DSP), for example. However, the CA computer could also be responsible for averaging the signals. In this case, the computer CA receives the signals delivered by the sensor (s) CF, averages these signals, and transmits the averaged signals to the ES recorder so that it stores them.

In the second step 30-50, of the calibration process, we start by removing the PC plate from the CF sensor, then the haptic wall PH is temporarily fixed on the CF sensor (s) and the PC plate on the PH haptic wall.

These temporary fixings can be done by any type of pressure tightening (clamping jaws, clamping screws, elastic) or by adhesion (adhesive tape, temporary glue), for example.

Once these temporary fixings have been made, the second step 30-50 continues with the application of the predefined force FP on the plate PC with the same finger DU, while carrying out the predefined relative displacements of this finger DU with respect to to the plate PC with passage of the finger DU by the element in relief ER and by simultaneously recording second signals s2 delivered by the sensor CF.

The recording of the second signals s2 delivered by the sensor (s) CF is carried out by the ES recorder of the AC calibration apparatus.

The number of relative displacements (and therefore passages) made in the second step 30-50 is preferably equal to the number N used in the first step 10-20. The objective is in fact the same, namely to record second signals s2 which result from averaging and therefore which are representative of the average force F2 exerted during the passage by the element in relief ER in the presence of the plate PC and of the haptic wall PH.

We schematically illustrated in Figure 5, in a diagram, an example of a time course curve (t) of the average force F2 represented by the second signals s2 recorded during the second step 30-50.

Once the second signals s2 have been recorded, the second step 30-50 continues with the determination by the computer CA of a transfer function FT between the first si and second s2 signals.

The term “FT transfer function” is understood here to mean a mathematical function making it possible to pass the first signals if the second s2 signals (ie FT (sl) = s2). Here, FT (sl) = tf (s2) / tf (s 1) in the frequency domain, tf being the Fourier transform.

In the third step 60-80, of the calibration process, we start by removing the PC plate from the haptic wall PH, then we apply the predefined force FP on the haptic wall PH with the same finger DU, while performing the relative movements of the finger with respect to the haptic wall PH and by simultaneously recording third signals s3 delivered by the sensor (s) CF.

The recording of the third signals s3 delivered by the sensor (s) CF is carried out by the ES recorder of the AC calibration apparatus.

The number of relative displacements (and therefore passages) made in the third step 60-80 is preferably equal to the number N used in the first 10-20 and second 30-50 steps. The objective is indeed the same, namely to record third signals s3 which result from averaging and therefore which are representative of the average force L3 exerted by the finger DU in the presence of the only haptic wall PH. This average force L3 represents the haptic effect created by the haptic wall PH and felt by the finger DU, but biased by the dynamics of the whole (PH / CL).

We schematically illustrated in Figure 6, in a diagram, an example of a time course curve (t) of the average force L3 represented by the third signals s3 recorded during the third step 60-80.

Once the third signals s3 have been recorded, the third step 60-80 continues with the application by the computer CA of the inverse (FT ¹ ) of the transfer function PT determined in the second step 30-50 to third signals s3 recorded in order to determine fourth signals s4 which are representative of the haptic effect created by the haptic wall PH and felt by the finger DU, but this time corrected and therefore not biased by the dynamics of the whole (PH / CP). We then have FT * (s3) = s4.

We schematically illustrated in Figure 7, in a diagram, an example of a time evolution curve (t) of the force F4 represented by the fourth signals s4 determined during the third step 60-80.

The invention makes it possible to take into account the changes in dynamics caused by the fixing of the haptic wall PH (additional mass) on the sensor (s) of a set (PH / CF), but also and especially those generated by the contact of the DU finger on the whole (PH / CF) (modification of mass and damping), which is impossible with known traditional methods.

It will be noted that when the sensor (s) CF deliver signals representative of a first normal force and of a second tangential force, two first signals are stored if (representing the normal forces F1 normal and tangential) , two second signals s2 (representing the average forces F2 normal and tangential) and two third signals s3 (representing the average forces F3 normal and tangential), and two fourth signals s4 (representing the forces F4 normal and tangential) are determined.

We schematically illustrated in Figure 8 an example of algorithm implementing the first 10-20, second 30-50 and third 60-80 steps of the calibration process described above.

In a first sub-step 10 of the first step, the CF sensor of a set (PH / CF) to be calibrated is temporarily fixed to the PC plate of the AC calibration apparatus.

Then, in a second sub-step 20 of the first step, a predefined force FP is applied to the plate PC with a finger DU of a user, while carrying out the predefined relative movements of this finger DU with respect to the PC plate with passage of the finger DU by the element in relief ER and simultaneously recording the first signals if delivered by the sensor CF by means of the recorder ES of the calibration device AC.

Then, in a third sub-step 30 of the second step, the PC plate is removed from the CF sensor, then the haptic wall PH is temporarily fixed on the sensor (s) CF and the PC plate on the wall haptic PH.

Then, in a fourth sub-step 40 of the second step, the predefined force FP is applied to the plate PC with the same finger DU, while carrying out the predefined relative displacements of this finger DU with respect to the plate PC with passage of the finger DU by the element in relief ER and simultaneously recording second signals s2 delivered by the sensor CF by means of the recorder ES.

Then, in a fifth sub-step 50 of the second step one (the computer CA) determines a transfer function FT between the first s 1 and second s2 signals. Then, in a sixth sub-step 60 of the third step, the PC plate is removed from the PH haptic wall.

Then, in a seventh sub-step 70 of the third step, the predefined force FP is applied to the haptic wall PH with the same finger DU, while making the relative movements of the finger relative to the haptic wall PH and in simultaneously recording third signals s3 delivered by the sensor (s) CF by means of the ES recorder.

Then, in an eighth sub-step 80 of the third step, we (the computer CA) apply the inverse (FT ¹ ) of the transfer function FT determined in the fifth sub-step 50 to the third signals s3 recorded in the seventh substep 70 in order to determine fourth signals s4 which are representative of the unbiased haptic effect created by the haptic wall PH and felt by the finger DU.

Note that in Figures 1 to 3 the processing and control means of the AC calibration device are very schematically illustrated by the only computer CA. However, these processing and control means can take the form of a box comprising integrated (or printed) circuits, or else several integrated (or printed) circuits connected by wired or non-wired connections. The term integrated circuit (or printed circuit) means any type of device capable of performing at least one electrical or electronic operation. Furthermore, as mentioned above, the CA computer can comprise at least one processor, for example of digital signal (or DSP (Digital Signal Processor)), a random access memory to store instructions for the implementation by this processor of a program or routines, and a mass memory in particular for the storage of any intermediate data involved in the calculations. The computer CA receives at least the signals if at s3 to use them in calculations, possibly after having shaped and / or demodulated and / or amplified them, in a manner known per se. The AC calibration device can also include an input interface for receiving commands or instructions and receiving the signals delivered by the CL sensor (s), and an output interface, in particular for transmitting the results. of its calculations (fourth signals s4).

Claims (1)

Claims [Claim 1] Calibration method for a haptic wall (PH) intended to be fixed on at least one sensor (CF) delivering signals representative of at least one force exerted on it, characterized in that it comprises i) a first step (10 -20) in which a plate (PC) provided with a raised element (ER) is fixed on said sensor (CF), then a predefined force is applied to said plate (PC) with a finger (DU) of a user, while carrying out predefined relative movements of said finger (DU) relative to said plate (PC) with passage of said finger (DU) through said element in relief (ER) and simultaneously recording first signals delivered by said sensor (CF ), ii) a second step (30-50) in which said plate (PC) is removed from said sensor (CF) and then said haptic wall (PH) is fixed on said sensor (CF) and said plate (PC) on said wall haptic (PH), then applying said predefined force on said plate (PC) with said finger (DU), while performing t said relative movements of said finger relative to said plate (PC) with passage of said finger (DU) through said relief element (ER) and simultaneously recording second signals delivered by said sensor (CF), and a function of transfer between said first and second signals, and iii) a third step (60-80) in which said plate (PC) is removed from said haptic wall (PH) and then said predefined force is applied to said haptic wall (PH) with said finger (DU), while performing said relative movements of said finger (DU) relative to said haptic wall (PH) and simultaneously recording third signals delivered by said sensor (CF), then the inverse of said function is applied transfer determined to said third recorded signals in order to determine fourth signals representative of a haptic effect created by said haptic wall (PH) and felt by said finger (DU). [Claim 2] Method according to claim 1, characterized in that in said first (10-20) and second (30-50) steps, a plate (PC) is used provided with an element in relief (ER) chosen from a branch, a rib , a hole, a boss and a texture. [Claim 3] Method according to claim 1 or 2, characterized in that in said first (10-20) and second (30-50) steps a plate (PC) is used provided in a central position with said element in relief (ER). [Claim 4] [Claim 5] [Claim 6] [Claim 7] [Claim 8] Method according to one of claims 1 to 3, characterized in that in said first (10-20), second (30-50) and third (60-80) stages, relative movements of said finger (DU) are carried out in two opposite directions from a single chosen direction and at a predefined speed. Method according to one of claims 1 to 4, characterized in that in said first (10-20), second (30-50) and third (60-80) steps a six-axis type sensor (CF) is used and delivering signals representative of first and second forces exerted on it in respectively normal and tangential directions. Method according to one of claims 1 to 5, characterized in that in said first (10-20), second (30-50) and third (60-80) stages said sensor (CF) is fixedly secured on a support ( SF) fixed and said finger (DU) is moved relative to said support (SF). Method according to one of claims 1 to 5, characterized in that in said first (10-20), second (30-50) and third (60-80) stages said sensor (CF) is fixedly secured on a support and said support is moved relative to said finger (DU). Calibration apparatus (AC) for calibrating a haptic wall (PH) intended to be fixed on at least one sensor (CF) delivering signals representative of at least one force exerted on it, characterized in that it comprises i) a support (SF) on which said sensor (CF) is fixed, ii) a plate (PC) provided with a raised element (ER) and intended to be fixed on said sensor (CF) in a first step (10-20 ) then on said haptic wall (PH) when the latter (PH) is fixed on said sensor (CF) in a second step (30-50), iii) a recorder (ES) recording a) first and second signals delivered by said sensor (CF) when a predefined force is applied to said plate (PC) with a finger (DU) of a user and that predefined relative movements of said finger (DU) relative to said plate (PC) are carried out with passage of said finger (DU) through said relief element (ER), during respectively said first (10-20) and second (30-50) step s, and b) third signals delivered by said sensor (CF) when said predefined force is applied to said haptic wall (PH) with said finger (DU) and when said predefined relative displacements of said finger (DU) with respect to said wall haptics (PH) are carried out during a third step (60-80) in which only said haptic wall (PH) is fixed to said sensor (CF), and iv) a computer (CA) determining a transfer function between said first and second recorded signals, and applying the inverse of said determined transfer function to said third recorded signals to determine fourth signals representative of a haptic effect created by said haptic wall (PH) and felt by said finger (DU). [Claim 9] Apparatus according to claim 8, characterized in that said support (SF) is fixed and said finger (DU) is moved relative to said support (SF). [Claim 10] Apparatus according to claim 8, characterized in that it comprises displacement means to which said support (SF) is fixedly secured and effecting said predefined relative movements of said support (SF) relative to said finger (DU).