Configure human-machine interface including a utensil and an array of magnetometers

A configurable human-machine interface for controlling an electrical apparatus includes at least one permanent magnet rigidly connected to each of utensils and a magnetometer array including N triaxial magnetometers, mechanically linked to each other without any degree of freedom to retain a known distance between each of the magnetometers, wherein N is a whole number greater than or equal to five, and a processing unit configured to: define, for each permanent magnet of a utensil, a value of at least one variable encoding a position or orientation of same in a three-dimensional reference system fixed without any degree of freedom to the array or the amplitude of the magnetic moment of same, from measurements of the magnetometers of the array, and automatically select a control law based on the value defined for the variable.

The invention relates to a configurable human-machine interface for controlling an electrical apparatus. The invention also relates to a method for controlling an electrical apparatus with such a configurable human-machine interface and also to an information recording medium for carrying out this method.

Human-machine interfaces are used in a very large number of different technical fields for controlling an electrical apparatus. For example, the electrical apparatus may be a robot, a computer screen, a games console or any type of electrical or electronic apparatus that must be controlled by a human being.

So as to be able to adapt to different electrical apparatuses, or to different situations, it is desirable for the human-machine interface to be configurable. Configurable human-machine interfaces comprise:at least one movable utensil, each utensil being actuatable directly by the hand of a user so as to pass between at least one first state of control of the electrical apparatus and a second state,a processing unit able:to automatically select a control law to be associated with the utensil actuated by the user from a number of different control laws of the electrical apparatus, each control law associating a first control of the electrical apparatus with the first state of a utensil and a second, different control or no control of the electrical apparatus with the second state of this same utensil, andto generate and to transmit a control to the electrical apparatus depending on the current state of the utensil and depending on the control law that has been selected for this utensil.

The control law associated with a utensil determines the functioning of this utensil in a given configuration of the interface. Consequently, in these human-machine interfaces, since the control law associated with a utensil is automatically selected, it is easy for the user to modify the configuration of this machine interface:by replacing one utensil with another, orby adding an additional utensil, orby removing a utensil, orby moving a utensil, for example so as to adapt to a left-handed or right-handed user.

However, the realization of such a configurable human-machine interface is complex. For example, it has been proposed to equip each utensil with an emitter, which sends to the processing unit an identifier of the control law to be used with this utensil. However, it is necessary to supply power to this emitter, which complicates the realization of the configurable human-machine interface.

The following prior art documents are also known: US2013/009907A1, US2003/095115A1 and WO99/66997A1.

The invention aims to overcome this disadvantage by proposing a configurable human-machine interface that can be realized more easily. The invention therefore relates to such a human-machine interface according to claim1.

In the above human-machine interface, the processing unit is able to select the control law to be associated with a utensil on the basis of the features of a permanent magnet with which the utensil is equipped. Thus, in this interface, it is not necessary to supply power to an emitter or another similar device, which simplifies the realization of the human-machine interface.

The embodiments of this human-machine interface may comprise one or more of the features of the dependent claims.

These embodiments of the human-machine interface also have the following advantages:use of the same magnetometer array to provide the measurements that make it possible both to select the control law and to establish the current state of the utensil, further simplifying the realization of the configurable human-machine interface;equipping of the utensil with a permanent magnet of which the direction of the magnetic moment is parallel to the axis of the utensil, making it possible to use this utensil as a joystick or cross-shaped button.

The invention also relates to a method for controlling an electrical apparatus according to claim5.

The embodiments of this control method may comprise one or more of the features of the dependent method claims.

These embodiments of the control method also have the following advantages:use of some of the variables to select the control law and of other variables to establish the current state of the utensil, thus simplifying the realization of the interface because the same permanent magnet is then used both to select the control law and to establish the state of the utensil;use of solely the variables encoding the orientation of the permanent magnet of the utensil, thus making it possible to dispose this same utensil in a very large number of different locations with respect to the magnetometer array without modifying the operation of said utensil;use of the variable values encoding the position of a permanent magnet of the utensil in order to select the control law to be associated with this utensil, thus making it possible to modify the operation of this utensil by displacing said utensil with respect to the magnetometer array;use of the relative position of a permanent magnet of the utensil with respect to another permanent magnet independent of this utensil, thus making it possible to modify the functioning of this utensil by modifying simply the relative position thereof with respect to this other separate permanent magnet;use of the amplitude of the magnetic moment of a permanent magnet with which the utensil is equipped in order to select the control law, thus making it possible to reconfigure, in a simple manner, the human-machine interface by replacing this utensil with another utensil equipped with a permanent magnet of which the amplitude of the magnetic moment is different;selection of the control law to be associated with a utensil on the basis of the relative position of different permanent magnets with which this utensil is equipped, thus making it possible to modify the configuration of the human-machine interface by replacing this utensil with another utensil equipped with permanent magnets of which the relative position with respect to one another is different.

The invention also relates to an information recording medium comprising instructions for executing the above method when these instructions are executed by an electronic computer.

In these figures, the same references are used to designate the same elements.

In the description below, the features and functions well known to the person skilled in the art are not described in detail.

FIG. 1shows a human-machine interface2making it possible to control an electrical apparatus4. Here, the electrical apparatus comprises a screen and a control unit5able to control the display of an image on this screen.

Here, the functioning of the interface2is illustrated in the case in which the unit5is a video games console. For example, the unit5controls the movement of a person6on the screen. However, the interface2can be used in numerous other applications, as is described at the end of this description.

The interface2comprises a number of utensils that can be actuated directly by hand by a human being, referred to hereinafter as the “user”. Each of these utensils comprises at least one permanent magnet. In order to simplifyFIG. 1, only one utensil10is shown in this figure. Other utensils of the interface2are described with reference toFIGS. 3 to 7. The interface2also comprises a device12for locating each utensil.

In this embodiment, in order to modify the configuration of the interface2, each utensil is freely movable, directly by the hand of the user, in an orthogonal coordinate system XYZ fixed without any degree of freedom to the device12. Here, the directions X and Y are horizontal and the direction Z is vertical. To this end, each utensil weighs less than a kilo and preferably less than 200 g. The dimensions of each utensil are sufficiently reduced so that said utensil can be gripped and moved by a single hand of the user.

In this embodiment the utensil10includes a lever14and a permanent magnet16having a magnetic moment not equal to zero, even in the absence of an external magnetic field. The lever14has an oblong shape so as to form a handle that can be easily gripped by the user. The lever extends along a longitudinal axis18. The lever14may be freely inclined by the user about any one of the axes X, Y and Z of the coordinate system XYZ. Here, the lever14is intended to be used as a joystick. For example, the lever14is made entirely of a non-magnetic material, i.e. a material devoid of any magnetic property measurable by the device12. This material is plastic, for example.

The utensil10is located on the basis of the position of the magnet16. Here, no limit is applied to the degrees of freedom of the utensil10. In particular, the utensil is not mechanically connected to the device12and may be used without mechanical contact with the device12.

Typically, the coercive magnetic field of the magnet16is greater than 100 A·m−1or 500 A·m−1. For example, it is made of a ferromagnetic or ferrimagnetic material.

The magnet16is fixed without any degree of freedom on the lever14. The direction of the magnetic moment of the magnet16is parallel to the longitudinal axis18of the lever14. InFIG. 1and the following figures the direction of the magnetic moment of a magnet is shown by an arrow. The greatest length of this magnet is designated L hereinafter. The power of the permanent magnet is typically greater than 0.01 A·m2or 0.1 A·m2.

The device12makes it possible to locate the magnet16in the coordinate system XYZ. Here, ‘locating’ means the determination of the position and of the orientation of the magnet16in the coordinate system XYZ. The position is defined without ambiguity by the values of three variables, for example the coordinates x, y and z of the magnet16in the coordinate system XYZ. More precisely, the variables x, y and z are the coordinates of the geometric center of the magnet16. The geometry center of an object is the barycenter of all the points of this object, with assignment of the same weight to each of these points. The orientation of the magnetic moment of the magnet16is defined without ambiguity by the values of two variables θyand θz. Here, the variables θyand θzare the angles of the magnetic moment of the magnet16with respect to the axes Y and Z respectively of the coordinate system. The device12also determines a sixth variable A. The variable A is the amplitude of the magnetic moment of the magnet16.

The device12for this purpose comprises an array of N triaxial magnetometers Mij. InFIG. 1the vertical wavy lines indicate a part of the device12that has not been shown.

Typically, N is greater than five and preferably greater than sixteen or thirty-two. Here, N is greater than or equal to sixty-four.

In this embodiment the magnetometers Mijare aligned in rows and in columns in order to form a matrix. Here, this matrix comprises eight rows and eight columns. The indices i and j identify, respectively, the row and the column of this matrix at the intersection of which the magnetometer Mijis located. InFIG. 1only the magnetometers Mi1, Mi2, Mi3, Mi4and Mijof a row i are visible. The position of the magnetometers Mijwith respect to one another is described in greater detail with reference toFIG. 2.

Each magnetometer Mijis fixed without any degree of freedom to the other magnetometers. To this end, the magnetometers Mijare fixed without any degree of freedom on a rear face22of a rigid plate20. This rigid plate has a front face24turned towards the magnet16. The plate20is made of a rigid non-magnetic material. The plate20is made of glass, for example.

Each magnetometer Mijmeasures the direction and the intensity of the magnetic field generated by the magnet16. For this, each magnetometer Mijmeasures the magnitude of the orthogonal projection of the magnetic field generated by the magnet16at this magnetometer Mijover three axes of measurement of this magnetometer. Here, these three axes of measurement are orthogonal to one another. For example, the axes of measurement of each of the magnetometers Mijare parallel respectively to the axes X, Y and Z of the coordinate system. The sensitivity of the magnetometer Mijis, for example, 4*10−7T.

Each magnetometer Mijis connected by way of an information-transmitting bus28to a processing unit30.

The processing unit30is able to determine the location of the magnet16in the coordinate system XYZ and the amplitude of the magnetic moment thereof on the basis of the measurements of the magnetometers Mij. To this end, the unit30comprises a programmable electronic computer32able to execute instructions recorded on an information recording medium. The unit30thus also comprises a memory34containing the instructions necessary for the execution by the computer32of the method ofFIG. 9. In particular, for each number P of magnetic objects able to be used simultaneously in the interface2, the unit30implements a mathematical model MPassociating each measurement of a magnetometer Mijwith the positions, orientations and amplitudes of the magnetic moments of P magnetic objects in the coordinate system XYZ. Each model MPis present in the form of a system of equations in which a first set of variables represents the positions and orientations of the P magnetic objects as well as the amplitudes of the magnetic moments of these objects. A second set of variables represents the measurements of the magnetometers Mij. To obtain the positions, orientations and amplitudes of the magnetic moments of the P magnetic objects, the variables of the first set are unknown and the values of the variables of the second set are known. This model is typically constructed on the basis of the physics equations of electromagnetism. This model is parameterized by the known distances between the magnetometers Mij. Here, the magnetic objects are the permanent magnets. To construct this model, each permanent magnet is approximated by a magnetic dipole. This approximation introduces only very few errors if the distance between the permanent magnet and the magnetometer Mijis greater than 2L and preferably greater than 3L, where L is the greatest dimension of the permanent magnet. L is typically less than 20 cm, and preferably less than 10 or 5 cm.

Here, the model MPis not linear. The unit30resolves this by implementing an algorithm for estimating its solution. For example, the algorithm used is an ensemble Kalman filter known more commonly by the name “unscented Kalman filter”.

Given that each magnetic dipole is characterized by three variables in order to know its position, two variables in order to know its orientation, and one variable in order to know the amplitude of its magnetic moment, the maximum number of magnetic dipoles that can be located simultaneously by the array of N magnetometers is less than N/2. Consequently, the value of the number P is less than or equal to N/2 and preferably less than N/5 or N/10 or N/20 so as to have redundant measurements. The redundancy of the measurements makes it possible to improve the accuracy of the locating of the dipoles.

The unit30is also able to transmit a control to the apparatus4by way of an interface36connected to this apparatus4.

The memory34also comprises a database38in which a plurality of control laws of the apparatus4are recorded. Each control law makes it possible to generate the control of the apparatus4corresponding to the current state of the utensil with which said control law is associated. To this end, each control law associates:a control of the apparatus4with at least one possible state of the utensil, andanother control of the apparatus4or an absence of control of the apparatus4with another possible state of the same utensil.

The control law thus determines how the apparatus4functions in response to the actuation, by the user, of the utensil associated with this control law. This database38is described in greater detail with reference toFIG. 8.

FIG. 2shows some of the magnetometers Mijof the device12. These magnetometers Mijare aligned in rows i parallel to the direction X. These magnetometers are also aligned in columns j parallel to the direction Y so as to form a matrix. The rows i and columns j are disposed in the order of increasing indices.

The center of the magnetometer Mijis located at the intersection of the row i and of the column j. The center of the magnetometer corresponds to the point where the magnetic field is measured by this magnetometer. Here, the indices i and j belong the range [1; 8].

The centers of two magnetometers Mijand Mij+1immediately in succession along a row i are separated by a known distance di,j,j+1. Similarly, the center of two magnetometers Mijand Mi+1,jimmediately in succession along the same column j are separated by a known distance dj,i,i+1.

In the particular case described here, whatever the row i, the distance di,j,j+1is the same. This distance is therefore denoted dj. Similarly, whatever the column j, the distance dj,i,i+1between two magnetometers is the same. This distance is thus denoted di.

Here, the distances diand djare both equal to d.

Typically, the distance d is less than, preferably two times less than, the shortest distance that may exist between two magnetic objects simultaneously present in front of the face24in the event of normal use of the interface2. Here, the distance d is between 1 and 4 cm when:the power of the permanent magnet is 0.5 A·m2,the sensitivity of the magnetometers is 4*10−7T, andthe number of magnetometers Mijis sixty-four.

FIGS. 3 to 7show other utensils that can be used instead of the utensil10or simultaneously with the utensil10in the interface2.

FIGS. 3 and 4show a cross-shaped button50. Typically, such a button is intended to indicate a direction of movement selected from four perpendicular directions of movement. The button50for this purpose comprises four keys52to57disposed at the ends of the arms of a cross58in the form of a “+” symbol. The cross58extends substantially in a plane perpendicular to an axis60passing through the geometric center of this cross. The axis60is fixed, with no degree of freedom, to the cross58. Here, the cross58forms merely a single block of matter made of a non-magnetic material. The cross58is connected to the base of a housing62via a connection64making it possible to incline the axis60with respect to the vertical in any direction when the base of the housing60is disposed horizontally. This connection64is a ball joint, for example.

The button50is also equipped with biasing means, able to permanently urge the cross58into its horizontal position. For example, these biasing means comprise identical springs arranged between each key52to55and a front face of the housing62.

The button50is actuated by the user in order to pass:from a rest state in which the cross58is in its horizontal position,into one pressed state from four possible pressed states.

Here, each pressed state corresponds to a state in which a single respective key52to55is pressed.

In order to determine the current state of the button50, a permanent magnet66is fixed without any degree of freedom to the cross58. For example, the magnet66is fixed to the cross58in such a manner that the direction of the magnetic moment of said magnet matches that of the axis60. In these conditions the current state of the button50may be established by using solely the inclination of the magnet66, i.e. the values of the variables θYand θZdetermined for this magnet66. Here, the values of the variables x, y, z and A of the magnet66are not used to establish the current state of the button50. By contrast, as explained hereinafter, the values of these four variables may be used to select the control law associated with the button50.

Here, the amplitude of the magnetic moment of the magnet66is unique, that is to say different from the amplitude of all the other permanent magnets that may be used in the interface2.

FIG. 5shows a steering wheel70mounted in rotation about an axis72. A steering wheel of this type is intended to be used for example to indicate an angle of rotation α. Here, the steering wheel70is fixed at the end of a shaft74extending along the axis72. The other, opposite end of the shaft74is mounted freely in rotation in a stand76intended to rest on the front face24of the device12. The shaft74and the stand76hold the steering wheel70in the air so as to facilitate the use thereof.

The steering wheel70may be turned manually by a user in order to assume an infinity of different states. In the case of the steering wheel70, each state corresponds to a unique value of the angle α. Here, the state in which the angle α is zero is referred to as the rest state.

In order to measure the angle α of the steering wheel70about the axis72, the steering wheel is equipped in this embodiment with two permanent magnets78and80. These magnets are fixed without any degree of freedom on the steering wheel70, for example in diametrically opposed positions with respect to the axis72. Here, these magnets78and80are identical. The direction of the magnetic moment of each of these magnets is tangent to a circle parallel to the plane in which the steering wheel70extends fundamentally and of which the center is located on the axis72. Here, in the rest state, the magnets78and80are symmetrical to one another with respect to a vertical plane. Consequently, any deviation from this rest state corresponds to an angle α different from zero.

Here, the angle α is determined solely on the basis of the orientation of the magnets70and80. The position of these magnets78and80and the amplitude A of these magnets may therefore be used to select the control law to be associated with this steering wheel70.

The amplitude of the magnetic moment of these magnets78and80is unique in the interface2.

FIG. 6shows a cursor90. This cursor for example makes it possible to control the value of a parameter of the electrical apparatus4. This cursor90for this purpose comprises a slide92mounted displaceably in translation in a rectilinear slot94formed in an upper face of a housing96. The user may slide the slide92by hand in order to modify the state of the cursor90. In the case of the cursor90, each state corresponds to a particular position of the slide92along the slot94.

In order to measure the position of the slide92along the slot94, the cursor90is equipped:with a permanent magnet98fixed without any degree of freedom to the slide92, andwith a permanent magnet100fixed without any degree of freedom to the housing96.

In these conditions, the state of the cursor90may be established by the relative position of the magnet98with respect to the magnet100. Here, the state of the cursor90is established on the basis of the value of the shortest distance d90between the geometric centers of the magnets98and100.

Consequently, the absolute position of the magnet100and orientation thereof may be used to select the control law to be associated with this cursor90.

In this embodiment the direction of the magnetic moment of the magnet100is parallel to the axis Z when the slot94extends horizontally. The amplitudes of the magnetic moments of the magnets98and100are unique in the interface2and are different from one another.

FIG. 7shows a button110. This button110is movable manually by a user between a rest state (shown inFIG. 7) and a pressed state. Typically, the button110is intended to trigger an action of the apparatus4solely when it has reached its pressed state.

This button110comprises a key112movable solely in translation along an axis114connected to a housing116between a rest position (shown inFIG. 7) and a pressed position. InFIG. 7the axis114is vertical. The rest and pressed states correspond, respectively, to the rest and pressed states of the key112.

The button110comprises biasing means, which permanently urge the key112into the rest position thereof. These biasing means here comprise a spring118disposed between a lower part of the button112and an upper face of the housing116.

A rectilinear rod120extends along the axis114, this rod120being fixed at one end without any degree of freedom to the key112and at the other end to a stop124. This rod120is mounted slidingly within an orifice122formed in the upper face of the housing116.

The stop124makes it possible to retain the lower end of this rod120within the housing116.

In order to determine the current state of the button110, the rod120comprises a permanent magnet126fixed without any degree of freedom on this rod. In this embodiment the direction of the magnetic moment of the magnet126matches the axis114.

Another permanent magnet128is also fixed without any degree of freedom on the base of the housing116.

Consequently, the current state of the button110may be established on the basis of the relative position of the magnet126with respect to the magnet128. For example, the state is established on the basis of the value of a distance d110and a threshold S0. The distance d110is the shortest distance separating the geometric centers of the magnets126and128. The threshold S0is used to discriminate the pressed state from the rest state. If the distance d110is lower than the threshold S0, this means that the button110is in its pressed state. Conversely, if the distance d110is greater than this threshold S0, the button110is in its rest state.

The distance d110is independent of the values of the variables x, y, A, θY, θZof the magnets126and128. Consequently, the value of these variables may be used to select the control law to be associated with this button110when used in the interface2.

FIG. 8shows in greater detail the database38. This database38comprises a number of pre-recorded control laws Li. In addition, it associates each pre-recorded law Liwith a selection condition Ci. If the condition Ciis verified by a permanent magnet or a pair of permanent magnets of a utensil, this control law is then associated with the utensil equipped with this magnet or pair of magnets. The index “i” identifies the control law Liand also the condition Ciassociated with this law Liby the database38. Each condition Cirelates to the values of the variables determined for the permanent magnets that equip a utensil and that generally are not used to establish the current state of this utensil.

By way of illustration, a number of examples of control laws and conditions associated with these control laws will now be described.

The law L1is a control law that uses solely the values of the variables θYand θZ. More precisely, it transforms each value of the angles θYand θZinto a respective control of the apparatus4. For example, this control may cause a movement of the person6in a direction specified by the values of the angles θYand θZ.

This law L1is associated with a condition C1. The condition C1is as follows: the value of the variable A must be between S1and S2, where S1and S2are predefined limits, such that only the amplitude of the magnetic moment of the magnet16is between these limits. This law L1is therefore intended to be associated with the utensil10. If the device12determines that the value of the variable A of a permanent magnet is between S1and S2, then it uses the law L1to convert the values of the angles θYand θZof this same magnet into a control of the apparatus4. Consequently, by modifying the inclination of the utensil10, it is possible to control the apparatus4. This remains true whatever the position of the utensil10with respect to the device12from the moment at which the presence of the magnet16can be detected. The location of the utensil10may therefore be selected freely by the user, which corresponds to a possible configuration infinity for the interface2.

The law L2is a control law identical to the law L1, but which generates different controls of the apparatus4for the same values of the angles θYand θZ. The law L2is associated with the condition C2. The condition C2is as follows:the value of the amplitude of the magnetic moment is between the limits S3and S4, andthe coordinates x, y and z of this permanent magnet are situated within a predefined zone VD.

The limits S3and S4are predefined limits such that only the amplitude of the magnetic moment of the permanent magnet66is between these limits. This law is therefore intended to be associated with the cross-shaped button50.

For example, the zone VDis the space located to the right of a median plane, where the right is the side labeled by the direction X of the coordinate system XYZ. The median plane is here a plane parallel to the axes Y and Z and that cuts the matrix of magnetometers Mijat the middle thereof. Consequently, the law L2is associated with the button60solely when this is disposed within the zone VD.

The law L3is identical to the laws L1and L2but generates different controls of the apparatus4for the same values of the angles θYand θZ.

The law L3is associated with a condition C3. The condition C3is identical to the condition C2except that the zone VDis replaced by a zone VG. The zone VGis the volume located to the left of the median plane defined before.

Thus, the law L3is associated with the button60, solely if this button is within the zone VG. This thus illustrates a case in which the operation of the same utensil is not the same depending on the location thereof with respect to the array of magnetometers Mij. In addition, by using such selection conditions, it is also possible to use simultaneously a copy of the button60in the zone VDand, simultaneously, another copy of the button60located within the volume VG. Although these two buttons are structurally identical, the operation of these two buttons is not the same, because the control laws that the processing unit associates with each of these buttons are not the same. This illustrates a situation in which the configuration of the interface2may be modified by displacing a utensil from a predefined zone into another predefined zone.

The law L4is a control law that uses solely the values of the variables θYand θZof two permanent magnets to control the apparatus4depending on the value of an angle of rotation α.

Typically, this law L4is designed to be associated with the steering wheel70. To this end, the law L4is associated by the base38with a condition C4. The condition C4is the following here: the values of the variables A for two separate permanent magnets simultaneously present in front of the face24are each between the limits S5and S6, where the limits S5and S6are predefined limits such that only the amplitude of the magnetic moment of the permanent magnets78and80is between these limits. With this condition C4, the same control law L4is associated with the steering wheel70whatever the location where said steering wheel is disposed on the face24. The user may therefore freely choose the location where he disposes the steering wheel70in the interface2.

The law L5is a control law that uses the value of a distance between two permanent magnets to generate a control for adjusting a parameter of the apparatus4depending on this distance. This law L5specifies that the distance is measured between:a permanent magnet of which the amplitude of the magnetic moment is between predefined limits S71and S81such that only the magnet98can satisfy this condition, anda permanent magnet of which the amplitude of the magnetic moment is between predefined limits S72and S82such that only the magnet100can satisfy this condition.

This control law is typically designed to be associated with the cursor90such that the distance corresponds to the distance d90. For this purpose, the law L5is associated with a condition C5. This condition C5is as follows:the value of the variable A of a permanent magnet is between the limits S72and S82, andthe value of the angle θZof this same permanent magnet is equal to zero, plus or minus 2%.

With such a condition C5, the law L5is associated with the cursor90only when this is positioned such that the slide92moves parallel to the face24. In addition, a single example of the cursor90must be disposed horizontally on the face24at a given moment.

The law L6is a control law identical to the law L5, but which generates different controls of the apparatus4for the same values of the distance d90. For this purpose, the law L6is associated with a condition C6. The condition C6is as follows here:the value of the variable A of a permanent magnet is between the limits S72and S82, andthe value of the angle θZis equal to 90°, plus or minus 2%.

With this condition C6, the law L6is associated with the cursor90only when this is positioned such that the slide92moves vertically. Thus, the conditions C5and C6make it possible to obtain a case in which the operation of the same utensil is modified depending on its orientation.

The law L7is a control law that uses only the shortest distance between two identical permanent magnets to generate a control of the apparatus4. Here, the law L7is intended to be associated with the button110, such that the shortest distance corresponds to the distance d110. For example, the control law L7is as follows:if the distance d110is greater than the threshold S0, then the unit30does not generate any control of the apparatus4, andif the distance d110is less than or equal to the threshold S0, then the unit30generates and transmits a control to the apparatus4.

The law L7is associated with a condition C7. Here, this condition C7is as follows:the values of the variables A of two separate permanent magnets are both between the limits S9and S10, andthe shortest distance between these two magnets is lower than a threshold Dmax110, andthe positions of these two permanent magnets do not belong to a zone V1.

The limits S9and S10are predefined constants, such that only the amplitude of the magnetic moment of the magnets126and128is between these limits. The value of the threshold Dmax110is selected to be equal to the greatest possible value of the distance d110.

The zone V1here is a volume of predefined dimension of which the location is defined by the position of at least one other magnet mechanically independent of those forming the pair of permanent magnets of this button110. For example, the zone V1is the half-space located to the right of a plane parallel to the axes Y and Z and passing through the geometric center of this other permanent magnet. Thus, the functioning of a copy of the button110is dependent on the relative position thereof with respect to this other permanent magnet. Here, for the other permanent magnet, the magnets126and128of another copy of the button110simultaneously present in front of the face24are used. Thus, the control law associated with one copy of the button110is dependent on the position thereof with respect to another copy of this same button.

The law L8is identical to the law L7except that for the same distance d110it generates a different control of the apparatus4. This law L8is associated with a condition C8. The condition C8is as follows:the values of the variables A of two separate permanent magnets are both between the limits S9and S10, andthe shortest distance between these two magnets is less than a threshold Dmax110, andthe position of these permanent magnets is within the zone V1.

Consequently, if just one button110is present in front of the face24of the device12, this button110is automatically associated with the law L7, since the location of the zone V1cannot be defined. By contrast, if two copies of the button110are simultaneously present in front of the face24, the copy of the button110that is located to the right of the other button is automatically associated with the law L8, whereas the law L7is associated with the other copy located more to the left. Thus, the conditions C7and C8illustrate a case in which the functioning of a utensil in the interface2is dependent on its relative position with respect to another utensil.

The functioning of the interface2will now be described in greater detail with reference to the method ofFIG. 9.

This method starts with a phase140of initialization, during which the different control laws Liand the different conditions Cifor selection of these control laws are recorded in the database38.

Then, a phase142of configuration of the interface2is performed. During this phase142, the user chooses one or more utensils from the utensils10,60,70,90and110. Here, it is assumed that there is only one copy of each of the utensils10and70and two copies of each of the utensils60,90and110. Then, the user disposes the utensils freely on the face24of the device12. In addition, the user ensures that the configuration realized does not result in there being, simultaneously, more than five permanent magnets in front of the face24. The human-machine interface is then configured.

It is then possible to proceed with a phase144of use of this interface.

The phase144starts by a step146in which the magnetometers Mijsimultaneously measure the magnetic field of the permanent magnet or magnets simultaneously present in front of the face24.

Then, during a step148, the unit30determines the position, orientation and amplitude of the magnetic moment of each of the permanent magnets present on the basis of the measurements of the magnetometers Mij.

For this, during an operation150, the unit30resolves the system of equations of the model M1at one magnetic dipole. The unit obtains a set of coordinates x1, y1, z1, θ1and φ1and an amplitude A1.

Then, during an operation152, the unit30calculates an error E1representative of the difference between:the estimation of the values measured by the magnetometers, calculated on the basis of the system of equations M1and on the basis of the positions, orientations and amplitudes obtained at the end of the operation150, andthe values of the measurements of the magnetometers actually measured during the step146.

In the case in which the algorithm used to resolve the model is an ensemble or extended Kalman filter, the resolution of this system of equations during the operation150generally provides an estimation of this error E1.

Steps150and152are carried out for P=1 up to P=5. The steps150and152for each value of P are preferably performed in parallel.

Then, during an operation154, the unit130selects the result obtained with the model MPgiving the smallest error EP. Thus, if there is only a single permanent magnet in front of the face24, the unit30automatically selects the model M1. If, by contrast, there are two permanent magnets, the unit30then automatically selects the model M2and so on.

At the end of this step148, the number of permanent magnets and the values of the variables x, y, z, θY, θZand A are known for each of these permanent magnets.

During a step160, the unit30automatically selects the control law to be associated with a permanent magnet or with a pair of permanent magnets by using the values of the six variables determined during the step148for each of these magnets. For this, the unit30firstly verifies if this permanent magnet or this pair of permanent magnets satisfies one of the conditions Ci. If so, the unit30automatically selects the control law Liassociated with the condition Cisatisfied in the database38and proceeds with a step164. If not, i.e. if this permanent magnet or this pair of permanent magnets does not satisfy any condition Ci, then the unit30repeats step160for another permanent magnet or another pair of permanent magnets. When there is no longer any permanent magnet or no longer any pair of permanent magnets to test, the method returns to step146.

For example, during the step160, if there is a permanent magnet of which the amplitude of the magnetic moment is between the limits S1and S2, the unit30automatically selects the law L1as being the law to be associated with the utensil equipped with this permanent magnet.

Each time a condition Ciis met, during a step164, the unit30establishes the state of the utensil on the basis of some of the variables x, y, z, θY, θZand A determined during the step148for this permanent magnet or this pair of permanent magnets. For example, in the case of the permanent magnet16, the unit30calculates the inclination of the utensil10on the basis of the values of the angles θYand θZ.

Once the state of the utensil has been established, during a step166, the unit30generates a control of the apparatus4by using the control law selected during the step160and the state established during the step164for this permanent magnet or this pair of permanent magnets. For example, in the case of the utensil10, the unit30generates a control of the apparatus4so that the person6moves in the direction in which the user has slanted the utensil10.

Then, during a step168, the unit30transmits the control thus generated to the apparatus4.

During a step170, the apparatus4executes the transmitted control and in response performs an action depending on the transmitted control.

The steps164to170are repeated for each permanent magnet or pair of permanent magnets satisfying one of the conditions Cicontained in the database38.

In parallel with the steps146to170, during a step172, the user freely actuates the utensil or utensils disposed on the face24to control the apparatus4.

When the user wishes to reconfigure the interface2, he returns to the phase142. During this new execution of the phase142, the user can modify the configuration of the interface2, for example:by removing or by adding a utensil, and/orby moving a utensil in order to change its functioning.

Thus, the interface2is easily configurable whilst remaining easy to fabricate.

Numerous other embodiments are possible. For example, the front face24is not necessarily planar. For example, in a variant, said front face is formed in relief. Typically, this form in relief may comprise hollow seats intended to receive and to immobilize the utensils in these seats.

In a variant the inclination of a utensil comprising two permanent magnets is determined on the basis of the position of each of these permanent magnets and not only on the basis of the direction of the magnetic moment of one of these magnets. In addition, if these two permanent magnets have different magnetic moments, it is also possible to determine a direction on the basis of the positions of these permanent magnets.

Utensils other than those described above can be realized and used in the interface2. For example, the cross58may be replaced by a disk. This makes it possible to indicate a direction of movement from an infinity of directions of movement by inclining the disk in this direction. In another variant the shaft74and the stand76are omitted. The user may then freely move the steering wheel with respect to the face24.

Numerous different control laws may be developed. For example, the control of the apparatus4may be dependent on the speed or the acceleration of a permanent magnet with which one of the utensils is equipped. In another example the control law associated with the button110is a continuous function of the distance d110. In this case, due to the presence of the spring118, this control law is dependent on the pressure exerted by the user on the key112.

It is also possible to associate a number of control laws with the same utensil during use thereof. For example, in addition to the law L1, a control law L11could at the same time be associated with the utensil10, said control law generating controls of the apparatus4depending on variables other than those used in the law L1. For example, the law L11is as follows: if z is greater than a predetermined threshold S11then a specific control is transmitted to the apparatus4, whereas if z is lower than S11this specific control is not transmitted. The specific control triggers, for example, a jump of the person6when moving in the direction in which the user has slanted the utensil10. The control laws L1and L11may also be regrouped within one and the same control law associated with the same selection condition C1.

In order to be capable of associating different control laws with the same utensil or with different utensils, it is not necessary to record a number of control laws in the database38. In a variant a single parameterized control law is recorded in the memory34, and each condition Ciis associated with a respective set of values for the different parameters of this control law.

Numerous other selection conditions may be conceived. For example, the selection condition may test if the inclination of a magnetic moment of a permanent magnet of the utensil is within a predetermined range of values and, only if so, may associate a control law Lkwith the utensil equipped with this permanent magnet. A button can thus be provided that is associated with a first control law when it is the right way up and that is associated with another control law when it is used upside down.

The condition making it possible to select the control law to be associated with a utensil does not necessarily test the value of the variable A. For example, if the interface comprises only a single utensil or only a number of identical copies of this same utensil, it is then not necessary to test the value of the amplitude of the magnetic moment of the permanent magnet of this utensil because it is the same for all the copies. In this case the control law is selected for example solely depending on the position of the permanent magnet with respect to a predefined zone.

It is also possible to define conditions verifying if the position of a permanent magnet is not situated within a predefined volume but in a particular position with respect to a fixed point of the coordinate system X, Y, Z or at a point of which the position is defined by another permanent magnet separate from the utensil.

A condition Cimay also test if a particular relative position of at least two permanent magnets with which the same utensil is equipped is occupied. If so, this makes it possible to identify this utensil and therefore to select a control law to be associated with this utensil. In this case it is then not necessary to use the amplitude of the magnetic moments to select the control law to be associated with this utensil.

If the number P of permanent magnets simultaneously present in front of the face24is known in advance, the control method may be simplified by using only the corresponding model MPto determine the position, the orientation and the amplitude of the magnetic moment of these P permanent magnets. For example, the number P of permanent magnets is grasped by the user during the configuration phase. The selection of the model having the minimal error EPmay thus be omitted.

In a variant the human-machine interface2may comprise only a single utensil, of which the operation changes depending on its position with respect to the array of magnetometers Mij.

In another variant the permanent magnets used to automatically select the control law to be associated with a utensil are not the same as those used to establish the current state of the utensil. It is also possible to establish the current state of the utensil by using sensors other than the magnetometers Mijand without using for this purpose a permanent magnet with which the utensil is equipped.

The processing unit and the magnetometers Mijmay be simplified in order to determine solely the variable or variables necessary for the automatic selection of the control law and for the establishment of the state of the utensil. The number of values of variables determined for each permanent magnet may therefore be less than six. For example, in a simplified embodiment in which the amplitude of the magnetic moment and the orientation of each permanent magnet are known in advance, only the position of each permanent magnet is determined. Such a situation may be encountered for example if only one copy or a number of copies of the button110disposed on the planar face24is/are used.

The change in configuration of the interface2is not necessarily performed directly by hand by the user. In another variant the interface comprises electric actuators making it possible to modify the configuration of the interface. For example, for this purpose, the movement of the utensils or the replacement of these utensils by other utensils is motorized, such that the user does not himself have to manipulate each of these utensils.

The number of possible configurations of the interface2may be limited by a mechanical device. Thus, in a variant, the human-machine interface comprises a rail and the utensil, such as the utensil10,50,70,90or110, is mounted slidingly on this rail such that it can be moved only along this rail in order to change the configuration of the interface2. In another variant it is also possible to limit the number of locations in which a utensil may be disposed with respect to the front face24. For this, the interface2comprises a number of locations, each equipped with its own coding to prevent the fixing in this location of a certain number of utensils and, by contrast, to allow the fixing in this location of other different utensils.

The approximation used to construct the Kalman filter may also be a quaternary approximation or greater, i.e. the equations of electromagnetism are approximated to an order greater than that corresponding to the dipolar approximation.

Numerous different methods can be used to determine the position and the orientation of the magnetic object. For example, the method described in US6269324 can be used. These methods do not necessarily use a Kalman filter. For example, the methods described in US2002/171427A1 or US6263230B1 are possible.

The magnetometers of the magnetometer array are not necessarily arranged in columns and in rows. They may also be arranged in other designs. For example, the magnetometers are disposed at each apex of each triangular or hexagonal mesh of a pattern of a plan.

The arrangement of the magnetometers with respect to one another may also be random or irregular. Thus, the distance between two immediately successive magnetometers in the array is not necessarily the same for all the pairs of two immediately successive magnetometers. For example, the density of magnetometers in a given zone of the array may be greater than elsewhere. Increasing the density in a given zone may make it possible to increase the accuracy of the measurement in this zone.

The array of magnetometers may also extend in three directions that are not collinear in space. In these conditions the magnetometers are distributed within a three-dimensional volume.

The number N of magnetometers may also be greater than or equal to sixty-four or ninety.

The magnetometers of the magnetometer array are not all necessarily identical to one another. In a variant the magnetometers do not all have the same sensitivity. In this case the less accurate magnetometers are disposed for example in the proximity of the center of the array whereas the more accurate magnetometers are disposed at the periphery of this array. Such an embodiment has the advantage of placing those magnetometers that are most difficult to saturate and therefore less sensitive in locations likely to be closest to the magnetic object. This also makes it possible to extend the zone of interaction.

The apparatus4may be replaced by any type of electrical apparatus that must be controlled in response to an action of a human being. For example, the apparatus controlled may be a robot, a machine tool, etc.

In all the embodiments described here, the permanent magnet may be replaced by a magnetic object not supplied with power permanently and that acquires a magnetic moment in the presence of a continuous external magnetic field, such as the geomagnetic field. For example, the permanent magnet is replaced by a part made of soft magnetic material. A magnetic material is considered to be soft if its coercive magnetic field is less than 10 or 1 A·m−1. Such a part has a magnetic moment created by the interaction between the geomagnetic field and the part made of soft magnetic material.