CONTROLLING THE MOVEMENT OF A MOBILE UNIT TO AN OBJECT BY ANALYSIS OF RADIO AND ACOUSTIC SIGNALS

Description

[0001] The present invention claims priority from French application No. 2100437 filed on 01 / 18 / 2021. Technical field of the invention

[0002] The invention relates to mobile boxes (or robots) which have to move towards objects, and more precisely to the control of the movements of such mobile boxes. State of the art

[0003] Some mobile boxes (or robots) are designed to move autonomously towards objects in order to perform at least one function. For this purpose, they include movement means which are responsible for moving them (and therefore moving them) autonomously on a rolling surface by analyzing data acquired by at least one onboard sensor. Here, "autonomous movement" means a movement which is controlled internally by a computer of the mobile box so that the latter can go from an initial location (such as, for example, a storage location) to a target location defined in relation to a target object.

[0004] This is the case, for example, of mobile charging boxes that are powered by a power cable connected to a base and are arranged to inductively recharge a battery of a remote object once they are placed under (at) a target location defined in relation to the latter. This is also the case, for example, of certain boxes (or robots) for mine clearance, or pollution control, or firefighting, or transport, or parameter measurement, or collection.

[0005] It is recalled that a charging box comprises a primary circuit comprising a primary coil supplied with current, by a power cable connected to its base, to transfer electrical energy by induction to a secondary coil forming part of a secondary circuit equipping a remote target object (such as for example a parked vehicle) and responsible for transforming the transferred electrical energy into charging current for the battery of this object. Such a charging box generally equips a garage or a parking lot (public or private) comprising parking spaces (or parking spaces) on which vehicles can park temporarily.

[0006] Generally, the acquired data that is analyzed by the computer of a mobile box (or robot) is environmental data, such as images acquired by at least one on-board camera. A disadvantage of this analysis method is that it has a relatively high error rate in determining the relative position of the target object with respect to the mobile box (or robot) due to the sensitivity of each on-board camera to light and the dirt that is deposited on the optics of each on-board camera.

[0007] Another method of analysis has been proposed. It requires equipping the target object with a specific radio signal transmitter and the mobile unit with at least one radio signal receiver, and periodically determining by means of the mobile unit's computer, by analyzing the received radio signals, the distance and direction separating a predefined location of the mobile unit from the target location defined in relation to the target object, then commands capable of moving the mobile unit towards the target location according to these determined distance and direction. A disadvantage of this other method of analysis lies in the fact that the positioning of the mobile unit (or robot) at the target location is relatively imprecise, which can reduce the effectiveness of the function provided, or even prevent it from being carried out.For example, in the case of a charging box, an offset of the centers of the primary and secondary circuits greater than 2 cm leads to a reduction in the efficiency of the recharge, which results in an increase in the duration of the recharge and / or a quantity of stored electrical energy lower than the targeted quantity.

[0008] WO2020 / 225226 A1 discloses a device and method for positioning a movable assembly relative to a fixed assembly using radio frequency or ultrasonic signals.

[0009] US 2016 / 223640 A1 discloses a method comprising receiving, at a user equipment, at least one radio signal and one audio signal; and determining, by the user equipment, a distance between the user equipment and at least one other device by determining at least one angle of arrival for the at least one radio signal and determining a time difference of arrival for the audio signal received via the microphone.

[0010] US 2016 / 223640 A1 discloses a charging system for a mobile station in which the mobile station autonomously navigates to the charging station identified by an image of the environment. The invention, as described in the independent claims, therefore aims in particular to improve the situation. Other aspects of the invention are defined by the dependent claims. Any other aspect of the description not defined by the claims must be considered as not forming part of the invention and only serves as an example for understanding it. Presentation of the invention

[0011] It proposes in particular for this purpose a control device, on the one hand, intended to equip a mobile box comprising at least one radio signal receiver and having to move to a target location defined in relation to an object emitting radio signals, and, on the other hand, comprising at least one processor and at least one memory arranged to carry out the operations consisting of periodically determining a distance separating a predefined location of the mobile box from this target location and a direction joining this predefined location and this target location by analysis of the radio signals received by each radio signal receiver, then commands capable of moving the mobile box towards the target location as a function of these determined distance and direction.

[0012] This control device is characterized by the fact that, when the mobile box also comprises at least one acoustic signal receiver and the object also emits acoustic signals, its processor and memory are arranged, once the mobile box has reached a predefined distance from the target location, to carry out the operations consisting of periodically determining the distance and direction by analyzing the acoustic signals received by each acoustic signal receiver, then commands suitable for moving the mobile box towards the target location according to these determined distance and direction, until the predefined location of the mobile box is placed at the target location.

[0013] Thanks to this two-phase movement of the mobile housing ("coarse" then "fine"), it is now possible to reliably obtain very precise positioning of the mobile housing, which guarantees the effectiveness of the function provided locally by the mobile housing.

[0014] The control device according to the invention may include other characteristics which may be taken separately or in combination, and in particular: its processor and memory may be arranged to perform the operations consisting, when the object emits radio signals having a predefined intensity, of periodically determining each distance by analyzing the intensity of the radio signals received by each radio signal receiver; its processor and memory may be arranged to perform the operations consisting, when the mobile housing comprises first and second radio signal receivers having respectively first and second reception pattern axes differing by 90°, of periodically determining first and second reception angles of the radio signals with respect to respectively the first and second reception pattern axes, then determining the direction from the determined first and second reception angles;in the presence of the latter option, its processor and its memory can be arranged to carry out the operations consisting of periodically determining a spatial sector containing the target location, among four spatial sectors subdividing into four a plane defined by the first and second reception diagram axes, as a function of the values ​​of the first and second reception angles determined, then determining the direction as a function of this determined spatial sector and the first and second reception angles;in the presence of the last sub-option, its processor and its memory can be arranged to carry out the operations consisting of considering that the target location is contained in a first spatial sector when the first and second reception angles are both positive, or that the target location is contained in a second spatial sector located to the right of the first spatial sector when the first reception angle is negative and the second reception angle is positive, or that the target location is contained in a third spatial sector located to the right of the second spatial sector when the first and second reception angles are both negative, or that the target location is contained in a fourth spatial sector located to the right of the third spatial sector and to the left of the first spatial sector when the first reception angle is positive and the second reception angle is negative;its processor and its memory can be arranged to carry out the operations consisting, when the mobile housing comprises at least first and second acoustic signal receivers, in periodically determining first and second instants of reception of identical acoustic signals, then in determining the distance and direction from these first and second determined instants of reception.;

[0015] The invention also proposes a mobile box comprising at least one radio signal receiver capable of receiving radio signals emitted by an object relative to which a target location is defined towards which the mobile box must move, at least one acoustic signal receiver capable of receiving acoustic signals emitted by this object, and a control device of the type presented above.

[0016] For example, this mobile box can be powered by a power cable connected to a base and arranged to inductively recharge a battery of the object once a predefined location it includes is placed at the target location.

[0017] The invention also proposes a control method, on the one hand, intended to control the movement of a mobile box, comprising at least one radio signal receiver, to a target location defined relative to an object emitting radio signals, and, on the other hand, comprising a first step in which a distance separating a predefined location of the mobile box from this target location and a direction joining the predefined location and the target location are periodically determined by analysis of the radio signals received by each radio signal receiver, then commands capable of moving the mobile box towards the target location as a function of these determined distance and direction.

[0018] This control process is characterized by the fact that: that, when the mobile box also comprises at least one acoustic signal receiver and the object also emits acoustic signals, its first step is carried out until the mobile box has reached a predefined distance from the target location, and that it then comprises a second step in which the distance and direction are periodically determined by analysis of the acoustic signals received by each acoustic signal receiver, then commands suitable for moving the mobile box towards the target location according to these determined distance and direction, until the predefined location of the mobile box is placed at the target location.

[0019] The invention also provides a computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing a control method of the type presented above for controlling the movement to a target location, defined relative to an object emitting radio signals and acoustic signals, of a mobile box comprising at least one radio signal receiver and at least one acoustic signal receiver. Brief description of the figures

[0020] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which: [ Fig. 1 ] schematically and functionally illustrates, in a top view, a parking installation comprising a driving surface comprising three parking spaces, on one of which a vehicle has just been parked, the battery of which must be recharged by induction by means of an exemplary embodiment of a mobile box according to the invention, [ Fig. 2 ] schematically and functionally illustrates an exemplary embodiment of a calculator comprising a control device according to the invention and intended to equip a mobile housing, [ Fig. 3 ] schematically illustrates within a diagram a plane subdivided into four spatial sectors by two perpendicular axes materializing the directions of the reception diagrams of two radio signal receivers, and on which are materialized the angles of reception by the latter of the radio signals coming from an object, and [ Fig. 4 ] schematically illustrates an example of an algorithm implementing a control method according to the invention. Detailed description of the invention

[0021] The invention aims in particular to propose a DC control device, and an associated control method, intended to allow the control of the autonomous movements of a mobile box (or robot) BM towards a remote (target) object V for the precise and reliable positioning of a predefined location ep which it comprises at the level of a target location ec defined in relation to this target object V.

[0022] In the following, it is considered, by way of non-limiting example, that the mobile box (or robot) BM is a charging box arranged so as to recharge by induction a battery BR of a remote object (target) V. But the invention is not limited to this type of mobile box. It in fact relates to any type of mobile box with autonomous movement having to perform at least one function. Consequently, it also relates to boxes (or robots) for mine clearance, or pollution control, or firefighting, or transport, or parameter measurement, or collection, for example.

[0023] Furthermore, it is considered in the following, by way of non-limiting example, that the (target) object V is a motor vehicle (whose battery BR must be recharged by induction). This is for example a car, as illustrated non-limitingly in the figure 1 . But the invention is not limited to this type of target object. It relates in fact to any type of target object towards which a mobile box (or robot) BM must move precisely to ensure locally at least one function. Consequently, it relates in particular to all vehicles (land, sea (or river) and air (including ULMs ("Ultra Light Motorized"), drones, helicopters and flying taxis)).

[0024] Furthermore, it is considered in the following, by way of non-limiting example, that the vehicle V comprises a powertrain of the all-electric type. But the vehicle could comprise a powertrain of the rechargeable hybrid type, that is to say comprising at least one thermal motor and at least one electric motor coupled to at least one rechargeable battery BR.

[0025] We have schematically represented on the figure 1 an example of an IN installation constituting a parking lot comprising a driving surface with three EPj parking spaces (j = 1 to 3). As illustrated, this IN installation is equipped with a charging system comprising at least one BF base and one BM mobile box (here for charging) interconnected by an AC power cable.

[0026] In the example illustrated without limitation on the figure 1 , the IN installation is equipped with only one charging system. But the IN installation could be equipped with several charging systems. Furthermore, in the example illustrated without limitation on the figure 1 , the charging system comprises only one mobile box BM connected to its base BF via an AC power cable. But the charging system SR may comprise several (at least two) mobile boxes BM connected to its base BF via associated power cables.

[0027] The mobile housing BM comprises in particular movement means MD which are arranged so as to enable it to move towards the object V to precisely position a predefined location ep which it comprises at a target location ec defined in relation to this object V.

[0028] For example, and as illustrated without limitation on the figure 1 , the movement means MD may comprise first and second tracked mechanisms driven in rotation by first and second electric motors (not shown) whose operations are controlled by an onboard computer CD. But as a variant, the movement means MD could comprise at least three holonomic (or omnidirectional) wheels, possibly with rollers, driven in rotation by electric motors independent of each other. Each electric motor may, for example, be powered by a battery, preferably rechargeable, which the mobile housing BM comprises (and which is not shown). It will be noted that it is possible (here) to consider taking advantage of the recharging phases of the vehicles V to recharge this battery via the AC power cable which is then powered by current.

[0029] The mobile box BM also comprises at least one radio signal receiver R1j capable of receiving radio signals emitted by a radio signal transmitter ES1 which the object V comprises, and at least one acoustic signal receiver R2k capable of receiving acoustic signals emitted by an acoustic signal transmitter ES2 which the object V comprises.

[0030] For example, the radio signal transmitter ES1 can be a Bluetooth type transmitter (possibly 5.1). In this case, each radio signal receiver R1j is a Bluetooth type receiver (possibly 5.1). But other types of radio signal transmitter / receiver can be used, preferably short or medium range.

[0031] Also, for example, the acoustic signal transmitter ES2 can emit sinusoidal acoustic signals, possibly with a frequency of 2000 Hz. In this case, each acoustic signal receiver R2k is a receiver suitable for receiving this frequency.

[0032] Due to the recharging function that the mobile box BM must provide, the latter comprises (here) at least one primary circuit responsible for transferring by induction electrical energy produced from a current supplied by the AC power cable (connected to the base BF). Part of the primary circuit, the computer CD and part of the movement means MD are housed in an internal space of the mobile box BM.

[0033] The primary circuit is coupled to a power source of the base BF via the AC power cable, and is here responsible for recharging the rechargeable battery BR of the object (here a vehicle) V, once the mobile box BM has positioned itself precisely below the latter (V) so that a predefined location ep that it comprises is placed at a target location ec defined with respect to the latter (V). Here, the predefined location ep is the center of a primary coil BP of the primary circuit, and the target location ec is placed at the center of a secondary coil BS of a secondary circuit CS of the object V (dedicated to induction charging and coupled to the (rechargeable) battery BR).

[0034] The secondary circuit CS of the vehicle V also comprises a capacitor associated with its secondary coil BS, which is capable of transforming electrical energy, transferred by the primary circuit of the mobile housing BM, into charging current for the battery BR. The primary coil BP of the primary circuit is associated with a capacitor and supplied with current by the AC power cable when it must transfer electrical energy by induction to the secondary coil BS of the secondary circuit CS, after having been positioned precisely under this secondary coil BS. Preferably, the primary coil BP of the primary circuit is placed on the upper (external) face of an upper wall of the mobile housing BM.

[0035] In the example described here, each acoustic signal receiver R2k may, for example, be installed in the vicinity of the center of the primary coil BP, and the acoustic signal transmitter ES2 may be installed under the vehicle V at a known location relative to the secondary coil BS and the target location ec. Similarly, each radio signal receiver R1j may, for example, be installed on the upper (external) face of the upper wall of the mobile housing BM, and the radio signal transmitter ES1 may be installed under the vehicle V at a known location relative to the secondary coil BS and the target location ec.

[0036] The AC power cable is preferably coupled to an automatic reel responsible for winding it, preferably in a controlled manner, so that it remains substantially taut during movements of the mobile housing BM. For example, this automatic reel may be part of the mobile housing BM. But it could be part of the base BF. It will be noted that the AC power cable is coupled to the primary circuit, possibly via at least one electronic circuit and / or at least one electronic component (possibly power).

[0037] The power supply source for the BF base can be a wall box (allowing the current intensity to be varied), for example connected to a power supply network (or mains) and responsible for the distribution of electrical energy and protection (circuit breakers, fuses, differential protection), or a power supply network (or mains).

[0038] The BM mobile box also necessarily includes a DC control device comprising, as illustrated non-limitingly on the figure 2 , at least one processor PR and at least one memory MD which are arranged to perform operations at least each time the mobile box BM is to be moved towards the object V.

[0039] It should be noted that in the example illustrated without limitation on the figure 2 , the DC control device is part of the CD calculator embedded in the mobile housing BM and produced in the form of a combination of electrical or electronic circuits or components (or "hardware") and software modules (or "software"). This is advantageous because it is this CD calculator which controls the electric motors of the means of movement MD. But in an alternative embodiment (not illustrated) the DC control device could be independent of the CD calculator, while being coupled to the latter (CD).

[0040] The PR processor may, for example, be a digital signal processor (or DSP). This PR processor may include integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is any type of device capable of performing at least one electrical or electronic operation. Thus, it may, for example, be a microcontroller.

[0041] The MD memory is live in order to store instructions for the implementation by the PR processor of at least part of the control method described later (and therefore of its functionalities).

[0042] The above-mentioned operations (of the processor PR and memory MD) consist first of all in periodically determining the distance d1, which separates the predefined location ep (of the mobile box BM) from the target location ec (defined with respect to the object V), and the direction d2, which joins this predefined location ep and this target location ec, by analyzing the radio signals received by each radio signal receiver R1j (of the mobile box BM). Then, these operations consist (during each period) in determining commands which are suitable for moving the mobile box BM towards the target location ec according to the distance d1 and direction d2 just determined, until the mobile box BM has reached a predefined distance dp from the target location ec.

[0043] For example, the preset distance dp can be between 50 cm and 100 cm.

[0044] Once the mobile box BM has reached the predefined distance dp from the target location ec, the operations consist (during each period) of determining the distance d1 and direction d2 by analyzing the acoustic signals received by each acoustic signal receiver R2k (of the mobile box BM). Then, these operations consist (during each period) of determining commands which are suitable for moving the mobile box BM towards the target location ec according to the distance d1 and direction d2 just determined, until the predefined location ep (of the mobile box BM) is placed at the target location ec.In the example described here, once this last placement has been carried out, the recharging of the battery BR of the object V can begin (it will be noted that it is following the transmission of its recharging request to the recharging system that the object V begins to emit its radio and acoustic signals, and it is at the start of the effective recharging phase that the object V stops emitting its radio and acoustic signals).

[0045] According to the invention, the movement of the mobile box BM is carried out in two phases: a first phase in which a "rough" approach is carried out to reach the predefined distance dp using the radio signals, and a second phase in which a "fine" or "final" approach is carried out to move from the predefined distance dp to the target location ec using the acoustic signals. This makes it possible to reliably obtain a very precise positioning of the mobile box BM (typically of the order of one or two centimeters), which guarantees the effectiveness of the function provided locally by the mobile box BM.

[0046] It should be noted that the movement of the mobile housing BM is controlled via a control of the rotations of the electric motors of the means of movement MD. In the presence of first and second electric motors, first Φd and second Φg rotations are therefore managed. In order to generate a control law to control these rotations, a kinematic model of the mobile housing BM can be defined, for example of the so-called "unicycle" type. The control variables are then the position (x, y) in an XY plane and the orientation θ in this XY plane.

[0047] The relationships between the rotation angles (Φd and Φg) of the electric motors and the positions (x, y) of the mobile box BM are then defined by the following differential equations: x ˙ y ˙ θ ˙ = r 2 cos θ r 2 cos θ r 2 sin θ r 2 sin θ − r 2 R r 2 R ⋅ ϕ ˙ g ϕ ˙ d , where r is the radius of the right and left wheels driving (here) the two tracks, 2R is the distance between these right and left wheels, and the point (“.”) above the variables denotes the derivative with respect to time. Knowing the initial conditions, it is possible to find the quantities (x, y, θ) from the rotation angles (Φd and Φg), for example by using encoders (rotation angle sensors) installed on the electric motors.

[0048] Noting u 1 the linear speed of the moving box BM ( u 1 = x ˙ 2 + y ˙ 2 ) , and u 2 the rotation speed ( u 2 = θ̇ ), we can control the mobile box BM with the following relation (1): ϕ ˙ g ϕ ˙ d = 1 r − R r 1 r R r ⋅ u 1 u 2 = A ⋅ u 1 u 2 .

[0049] Whatever the phase considered, once the target object V is located relative to the mobile box BM (i.e. when d1 and d2 are known), we can use a state feedback control law. In this case, if we call e the difference between the position of the mobile box BM and the position of the target object V, we can show that we can make ep converge towards ec using the following control law: u 1 u 2 = − k 1 − k 2 ⋅ A − 1 ⋅ e , where k1 and k2 are greater than 0. Furthermore, the commands to be supplied to the electric motors can be related by relation (1).

[0050] It will be noted that the processor PR and the memory MD can also be arranged to carry out the operations consisting, when the object V emits radio signals having a predefined intensity (and known to the control device DC), in periodically determining (in the first phase) each distance d1 by analyzing the intensity of the radio signals received by each radio signal receiver R1j. This method is known by the English acronym RSSI ("Received Signal Strength Indication"). It will be understood in fact that in the absence of an obstacle, the distance d1 can be deduced from the difference between the received intensity and the predefined intensity (at the place of emission).

[0051] It will also be noted, as illustrated without limitation on the figure 1 , that the mobile housing BM may comprise first R11 (j = 1) and second R12 (j = 2) radio signal receivers having respectively first a1 and second a2 reception diagram axes differing by 90°. In this case, the processor PR and the memory MD may be arranged to carry out the operations consisting of periodically determining first α1 and second α2 reception angles of the radio signals with respect to respectively the first a1 and second a2 reception diagram axes. Then, the processor PR and the memory MD may be arranged to carry out the operations consisting of determining the direction d2 from the first α1 and second α2 reception angles just determined. This method based on the measurement of the arrival angles α1 and α2 of the radio signals is known by the English acronym AoA (“Angle of Arrival”).For each receiver R1j, the angle αi is measured over the range [-90°; +90°] and the differentiation between radio signals coming from the front of a receiver R1j and those coming from the rear of this receiver R1j is determined due to the use of two receiver R1j.

[0052] In order to remove certain directional ambiguities, the PR processor and the MD memory can implement the space sectorization method described below with reference to the diagram of the figure 3 . Indeed, the processor PR and the memory MD can be arranged to perform the operations consisting of periodically determining a spatial sector containing the target location ec among four spatial sectors s1 to s4 which subdivide into four a plane defined by the first a1 and second a2 reception diagram axes (perpendicular to each other). This determination is made as a function of the values ​​of the first α1 and second α2 reception angles determined. Then, the processor PR and the memory MD can be arranged to perform the operations consisting of determining (for each period) the direction d2 as a function of the determined spatial sector and the values ​​of the first α1 and second α2 reception angles.

[0053] For example, the processor PR and the memory MD can be arranged to perform the operations of considering: that the target location ec is contained in a first spatial sector s1 when the first α1 and second α2 reception angles are both positive, or that the target location ec is contained in a second spatial sector located to the right of the first spatial sector when the first reception angle α1 is negative and the second reception angle α2 is positive, or that the target location ec is contained in a third spatial sector s3, located to the right of the second spatial sector s2, when the first α1 and second α2 reception angles are both negative, or that the target location ec is contained in a fourth spatial sector s4, located to the right of the third spatial sector s3 and to the left of the first spatial sector s1, when the first reception angle α1 is positive and the second reception angle α2 is negative.

[0054] In the example illustrated without limitation on the figure 3 , the first α1 and second α2 reception angles are both positive, which means that the target location ec is contained in the first spatial sector s1.

[0055] It will also be noted, as illustrated without limitation on the figure 1 , that the mobile housing BM may comprise first R21 (k = 1) and second R22 (k = 2) acoustic signal receivers. In this case, the processor PR and the memory MD may be arranged to perform the operations consisting of periodically determining first t1 and second t2 instants of reception of identical acoustic signals (from the acoustic signal transmitter ES2). Then, the processor PR and the memory MD may be arranged to perform the operations consisting of determining the direction d2 from these first t1 and second t2 instants of reception just determined. For example, the method of difference in arrival or reception time (t1 - t2), known by the English acronym TDOA ("Time Difference Of Arrival" - indication of strength of the received signal), may be used to determine the distance d1 and direction d2.

[0056] It will also be noted, as illustrated without limitation on the figure 1 , that the mobile housing BM can also comprise at least one ultrasonic sensor CU emitting ultrasound in a part of its environment to detect obstacles on its path and estimate the distance of the latter. In this case, the processor PR and the memory MD can be arranged to carry out the operations consisting of periodically implementing an obstacle avoidance method, such as for example that called “avoidance by limit fields” which uses a modeling of the obstacles in the form of circles in the XY plane of movement of the mobile housing BM, when it determines the controls of the electric motors of the movement means MD.

[0057] It will also be noted, as illustrated without limitation on the figure 2 , that the CD calculator can also comprise, here in addition to the RAM MD and processor PR of the DC control device, a mass memory MM, in particular for storing the intensities and reception angles of the determined radio signals, the times of reception of the acoustic signals, and any relative positions of the obstacles with respect to the mobile box BM, and intermediate data used in all its calculations and processing. Furthermore, this CD calculator can also comprise an input interface IE for receiving at least the intensities and reception angles of the determined radio signals, the times of reception of the acoustic signals, and any relative positions of the obstacles with respect to the mobile box BM, for use in calculations or processing, possibly after having shaped and / or demodulated and / or amplified them, in a manner known per se, by means of a digital signal processor PR'.In addition, this CD calculator can also include an IS output interface, in particular to deliver the commands of the electric motors of the MD means of movement determined by the DC control device.

[0058] The invention can also be considered in the form of a control method, intended to be implemented in the mobile housing BM described above, and comprising a first step 10-30 (of “rough” approach) and a second step 40-70 (of “fine” or “final” approach).

[0059] In the first step 10-30 (of the control method), the control device DC begins by periodically determining the distance d1, which separates the predefined location ep of the mobile box BM from the target location ec (defined with respect to the object V) and the direction d2 which joins this predefined location ep and this target location ec, by analyzing the radio signals received by each radio signal receiver R1j (of the mobile box BM). Then, the control device DC determines (at each period) commands which are suitable for moving the mobile box BM towards the target location ec according to the distance d1 and direction d2 just determined, until the mobile box BM has reached a predefined distance dp from the target location ec.

[0060] In the second step 40-70 (of the control method), the distance d1 and direction d2 are periodically determined (by the control device DC) by analyzing the acoustic signals received by each acoustic signal receiver R2k (of the mobile box BM). Then, the control device DC determines (at each period) commands which are suitable for moving the mobile box BM to the target location ec according to the distance d1 and direction d2 just determined, until the predefined location ep is placed at the target location ec.

[0061] It has been schematically illustrated on the figure 4 an example of an algorithm implementing a control method 10-70 according to the invention.

[0062] The algorithm comprises a sub-step 10 which begins when the control device DC is informed of a request to move towards the object V and the latter (V) begins to emit its radio and acoustic signals. In this sub-step 10, the control device DC determines the distance d1, which separates the predefined location ep of the mobile box BM from the target location ec, and the direction d2, which joins this predefined location ep and this target location ec, by analyzing the radio signals received by each radio signal receiver R1j.

[0063] Then, in a sub-step 20, one (the control device DC) determines commands suitable for moving the mobile box BM towards the target location ec as a function of the distance d1 and direction d2 determined in the sub-step 10.

[0064] Then, in a substep 30, it (the control device DC) determines whether the mobile box BM has reached a predefined distance dp from the target location ec. If not (“no”), it (the control device DC) returns to perform substep 10. If yes (“yes”), this means that the mobile box BM has reached the predefined distance dp from the target location ec, and therefore it (the control device DC) performs a substep 40. Substeps 10 to 30 constitute the first step of the control method.

[0065] In sub-step 40, the distance d1 and direction d2 are determined by analyzing the acoustic signals received by each acoustic signal receiver R2k.

[0066] Then, in a sub-step 50, one (the control device DC) determines commands suitable for moving the mobile box BM towards the target location ec as a function of the distance d1 and direction d2 determined in the sub-step 40.

[0067] Then, in a substep 60, it is determined (by the control device DC) whether the predefined location ep of the mobile box BM is placed at the target location ec. If not (“no”), it is returned to substep 40 by the control device DC. If yes (“yes”), this means that the predefined location ep is placed at the target location ec and therefore that the mobile box BM has reached its destination. The control method then ends in a substep 70.

[0068] Substeps 40 to 70 constitute the second step of the control process.

[0069] It will also be noted that the invention also proposes a computer program product (or computer program) comprising a set of instructions which, when executed by processing means of the electronic circuit (or hardware) type, such as for example the processor PR, is capable of implementing the control method described above to control the movement of the mobile box BM to a target location ec (defined relative to an object V emitting radio signals and acoustic signals).

Claims

1. Control device (DC) for a mobile box (BM) comprising at least one radio signal receiver (R1j) and having to move to a target location defined in relation to an object (V) emitting radio signals , said d control device (DC) comprising at least one processor (PR) and at least one memory (MD) arranged to carry out the operations consisting of periodically determining a distance separating a predefined location of said mobile box (BM) from said target location and a direction joining said predefined location and target location by analysis of said radio signals received by each radio signal receiver (R1j), then commands capable of moving said mobile box (BM) towards said target location as a function of said determined distance and direction, characterized in that that, said mobile box (BM) also comprises at least one acoustic signal receiver (R2k) and when said object (V) emits acoustic signals, said processor (PR) and memory (MD) are arranged, once said mobile box (BM) having reached a predefined distance from said target location, performing the operations consisting of periodically determining said distance and direction by analysis of said acoustic signals received by each acoustic signal receiver (R2k), then commands capable of moving said mobile box (BM) towards said target location according to said determined distance and direction, until said predefined location of the mobile box (BM) is placed at said target location.

2. Device according to claim 1, characterized in that said processor (PR) and said memory (MD) are arranged to carry out the operations consisting , when said object (V) emits radio signals having a predefined intensity , in periodically determining each distance in analyzing the intensity of said radio signals received by each radio signal receiver (R1j).

3. Device according to claim 1 or 2, characterized in that said processor (PR) and said memory (MD) are arranged to carry out the operations consisting of, when said mobile box (BM) comprises first (R11) and second (R12) receivers of radio signals having respectively first and second reception diagram axes differing by 90° , to periodically determine first and second reception angles of said radio signals with respect respectively to said first and second reception diagram axes, then to determine said direction from said first and second determined reception angles.

4. Device according to claim 3, characterized in that said processor (PR) and said memory (MD) are arranged to carry out the operations consisting of periodically determining a spatial sector containing said target location, among four spatial sectors subdividing into four a plane defined by said first and second reception diagram axes , as a function of the values of said first and second determined reception angles, then determining said direction as a function of said determined spatial sector and said first and second reception angles.

5. Device according to claim 4, characterized in that said processor (PR) and said memory (MD) are arranged to carry out the operations consisting of considering that said target location is contained in a first spatial sector when said first and second reception angles are both positive, or said target location is contained in a second spatial sector located to the right of said first spatial sector when said first reception angle is negative and said second reception angle is positive, or said target location is contained in a third sector spatial located to the right of said second spatial sector when said first and second reception angles are both negative, or else said target location is contained in a fourth spatial sector located to the right of said third spatial sector and to the left of said first spatial sector when said first reception angle is positive and said second reception angle is negative.

6. Device according to one of claims 1 to 5, characterized in that said processor (PR) and said memory (MD) are arranged to carry out the operations consisting, when said mobile box (BM) comprises at least first (R21) and second (R22) acoustic signal receivers , to periodically determine first and second times of reception of identical acoustic signals , then to determine said distance and direction from said first and second determined reception times.

7. Mobile box (BM) comprising at least one radio signal receiver (R1j) capable of receiving radio signals emitted by an object (V) in relation to which a target location is defined towards which said mobile box (BM) must move , characterized in that it further comprises at least one acoustic signal receiver (R2k) capable of receiving acoustic signals emitted by said object (V), and a control device (DC) according to one of the preceding claims.

8. Mobile box according to claim 7, characterized in that it is supplied with current by a power cable (CA) connected to a base (BF) and arranged so as to recharge by induction a battery (BR) of said object (V ) once a predefined location that it understands is placed at said target location .

9. Method for controlling the movement of a mobile box (BM) comprising at least one radio signal receiver (R1j), to a target location defined in relation to an object (V) emitting radio signals , said method comprising a first step (10-30) in which a distance separating a predefined location of said mobile box (BM) from said target location and a direction joining said predefined location and target location is periodically determined by analysis of said radio signals received by each radio signal receiver ( R1j), then commands capable of moving said mobile box (BM) towards said target location as a function of said determined distance and direction, characterized in that said mobile box (BM) also comprises at least one acoustic signal receiver (R2k ) and when said object (V) also emits acoustic signals, said first step (10-30) is carried out until said mobile box (BM) has reached a predefined distance from said target location, and in that it then comprises a second step (40-70) in which said distance and direction are periodically determined by analysis of said acoustic signals received by each acoustic signal receiver (R2k), then commands capable of moving said mobile box (BM) towards said target location according to said determined distance and direction, until said predefined location of the mobile box (BM) is placed at said target location.

10. Computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing the control method according to claim 9 to control the movement to a defined target location relative to an object (V) emitting radio signals and acoustic signals, a mobile box (BM) comprising at least one radio signal receiver (R1j) and at least one acoustic signal receiver (R2k).