FR3043210A1 - DEVICE AND METHOD FOR DETECTING OBJECTS - Google Patents

Abstract

The invention relates to an object detection device (100) comprising: - a transmitter (110) which is adapted to emit a light beam; - a receiver (150) which is adapted to emit an output signal (S2) depending on the characteristics of the light it receives, and - a computer (160) which is adapted to process the output signal to detect an object (11). According to the invention, the receiver is a photodiode and there is provided, in the path of the light beam emitted by the transmitter, a spatial light modulator (120).

Description

Device and method for detecting objects

Technical field to which the invention relates

The present invention relates generally to the detection of objects such as a hand of a user.

It relates more particularly to an object detection device comprising: a transmitter which is adapted to emit a light beam; a receiver which is adapted to emit an output signal according to the characteristics of the light which it receives (by example depending on the received light intensity), and - a computer which is adapted to process the output signal in order to detect an object in the field of the transmitter and the receiver.

It also relates to a method of detecting objects by means of such an object detection device.

It also relates to a system and a method of gesture control of an electronic device by means of such an object detection device.

Technological background

In the field of obstacle detection, there is known a device comprising a diode adapted to emit a light beam, and a photodiode for detecting a portion of this light beam after it has been reflected by an obstacle.

If such a detection device makes it possible to detect an obstacle and to determine the distance between this obstacle and the detection device, it does not unfortunately make it possible to determine the exact position of this obstacle.

Such a detection device is therefore not usable in the state in a more complex system, especially in a gesture control system of an electronic device.

Such a system, well known to those skilled in the art, proposes to detect a gesture or posture of the hand of a user, and to deduce a control instruction of a function of an electronic device.

The detection of the position in space and the shape of the hand of the user can then be done by means of a detection device incorporating a digital camera type "flight time".

In such a detection device, there is provided an infrared light source adapted to emit a light pulse (that is to say a "flash" of very short duration). The camera then records the light returned by the environment and, for each pixel, it measures the time between the moment when the flash was emitted and the moment the light reached the camera (we speak of "flight time" ), this provides the distance between the camera and the user's hand.

This detection device, which makes it possible to obtain the shape and the exact position of the user's hand in the space, presents good results.

It unfortunately requires the use of a digital camera type "flight time", which is particularly expensive, which thus reduces the scope of this detection device to only expensive electronic devices.

Object of the invention

In order to overcome the aforementioned drawback of the state of the art, the present invention proposes a new system based on the use of a less expensive light receiver.

More particularly, it is proposed according to the invention an object detection device as defined in the introduction, wherein there is provided, in the path of the light beam emitted by the transmitter, a spatial light modulator, and in which receiver has at least one photodiode.

The photodiode (very inexpensive) makes it possible to emit a simple output signal, typically an electrical signal whose intensity varies as a function of the intensity of the light received.

It can be used alone, to the benefit of the low cost of the device, or in combination with other photodiodes so that the output signal is spatially modulated.

The spatial light modulator is designed to modulate the components (intensity, phase, polarization) of the light emitted by the transmitter.

Associating the photodiode with the spatial light modulator makes it possible to emit light beams of different characteristics in the direction of an object, and then to compare the output signals received from the photodiode after each modulation of the light in order to determine the shape and the position of this object.

Thus, this method requires inexpensive means and it provides reliable results. Other advantageous and non-limiting features of the object detection device according to the invention are the following: the spatial light modulator comprises a matrix of micromirrors; the spatial light modulator comprises at least one liquid crystal panel; the spatial light modulator comprises a panel having a reflective silicon surface covered with a layer of liquid crystals; said emitter comprises a light-emitting diode; an illumination optic is provided adapted to focus the light beam after it has been modulated by said spatial light modulator; and - concentration optics adapted to focus the light towards the receiver are provided. The invention also relates to a gesture control system of an electronic apparatus, comprising an object detection device as mentioned above, the calculator of which includes a detection software adapted to determine the position and / or the displacement and / or the shape of said object as a function of each received output signal, and an interpretation software adapted to generate a command instruction of said electronic apparatus, as a function of the position and / or the displacement and / or the shape of said object.

Preferably, the computer comprises a memory in which is stored a database register, each record stores a command instruction associated with a position and / or a displacement and / or a particular form of a hand. The invention also proposes a method for detecting objects by means of an object detection device as mentioned above, comprising the steps of: a) controlling the spatial light modulator so that it presents a determined pattern , b) controlling the emitter to emit a light beam pulse, c) detecting, with said receiver, the light emanating from the reflection of the light beam on surrounding objects, and outputting an output signal according to the characteristics of the detected light, and d) processing, by means of said computer, the output signal to determine the position and / or the displacement and / or the shape of at least one of said objects. Other advantageous and non-limiting features of the object detection method according to the invention are the following: steps a) to c) are repeated with different patterns, and in step d), the position and / or the displacement and / or shape of said object is determined as a function of each output signal emitted by the receiver; - In step d), it is expected to remove from each output signal a component associated with the fixed objects detected; said component is read in a memory of the computer; and in step d), determining an approximate shape of said object, consisting of elements of simple geometries. Finally, the invention relates to a method of gesture control of an electronic device, by means of a gesture control system as mentioned above, in which it is intended to implement a method of detecting objects as mentioned above, then it is expected that the computer interprets the position and / or displacement and / or the shape of said object to deduce a control instruction of said electronic device.

Detailed description of an example of realization

The following description with reference to the accompanying drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be achieved.

In the accompanying drawings: - Figure 1 is a schematic perspective view of the interior of a passenger compartment of a motor vehicle, in which there is a driver; FIG. 2 is a schematic view of an object detection device according to the invention; and FIG. 3 is a diagram illustrating the method implemented by the object detection device of FIG. 2 for detecting an object.

In Figure 1, there is shown a portion of the passenger compartment of a motor vehicle 1.

Conventionally, this motor vehicle 1 comprises a frame which supports in particular a powertrain, a steering system (with a steering wheel 3) for varying the orientation of the steering wheels of the vehicle, the body elements and the cabin elements.

Among these cabin elements, the vehicle has a seat for a driver 10 to sit. It also includes a central electronic console 2 offering different functions, for example geolocation functions, audiovisual functions, temperature control functions in the passenger compartment ...

The motor vehicle 1 also includes an electronic control unit (or ECU for "Electronic Control Unit"), called here computer, including controlling the functions of the central electronic console 2 according to the wishes expressed by the driver 10.

In the context of the present invention, the motor vehicle 1 also comprises an object detection device.

This object detection device is here placed in the cabin, so as to detect the hand 11 of the driver 10 when the latter positions his hand 11 opposite the central electronic console 2.

In the embodiment described here and shown in the figures, this object detection device is part of a more global system, namely a gesture control system of the functions of the central electronic console 2.

It will be considered that this device for detecting objects will locate the hand 11 of the driver, to detect any element of gesture that can be interpreted to control one of the functions of the central electronic console 2. At this stage, we will define the expression "element of gesture" as designating a particular position of the hand (upwards, downwards, ...), or a particular gesture made with the hand (fingers folded, fingers crossed, open hand, closed fist, ...), or a particular movement of the hand (movement from right to left, movement from top to bottom, ...). It can thus be provided that each type of gesture element corresponds to a particular command of one of the functions of the central electronic console 2.

As is more particularly illustrated in FIG. 2, the object detection device 100 comprises, in addition to the aforementioned computer 160, a transmitter 110 which is adapted to emit a light beam and a receiver 150 which is adapted to emit an output signal. S2 function of the characteristics of the light that it receives.

These emitter 110 and receiver 150 are here placed in the passenger compartment of the motor vehicle 1, for example in the central electronic console 2 or in an inner part 4 of the roof.

According to a particularly advantageous characteristic of the invention, the receiver 150 comprises at least one photodiode and there is provided, in the path of the light beam emitted by the emitter 110, a spatial light modulator 120. Here, it will be considered that the receiver has a single photodiode.

It is recalled in this regard that a photodiode is a simple and inexpensive semiconductor component, which has the ability to detect light radiation and transform it into an output signal S2.

It is also recalled that a spatial light modulator is a device that makes it possible to modify the components (intensity, phase, polarization) of a ray of light. Such a spatial light modulator is well known to those skilled in the field of video projectors, so that it will not be described in detail here. The manner in which he will be employed will, however, be well described later in this talk.

As shown in Figure 2, the computer 160 is provided to control the transmitter 110, so that it emits a light beam. It is thus more precisely adapted to send a control signal S1 to this emitter 110. The emitter 110 is here formed by a light-emitting diode adapted to emit in a range of wavelengths that are not visible to the eye, for example in the infrared range (between 700 and 1000 nm). Alternatively, it could be another type of light source.

This emitter 110 is oriented so that its mean direction of illumination is directed towards the spatial light modulator 120.

This spatial light modulator 120 may be in different forms.

Preferably, it will be a matrix of micro-mirrors, commonly referred to by the initials DMD (of the English "Digital Micromirror Device"). This type of spatial light modulator will be preferred because it is the one that will work at higher frequencies.

In a variant, the spatial light modulator 120 could comprise one or more liquid crystal panels, commonly designated by the initials LCD (liquid crystal display). For example, it could comprise a single liquid crystal panel (we speak of monochrome technology) used in transmissive mode (that is to say, so that the light emitted by the transmitter 110 partially crosses it) .

Still in a variant, the spatial light modulator could comprise a panel having a reflective silicon surface covered with a layer of liquid crystals. This technology is more generally referred to by its initials LCOS ("Liquid Crystal on Silicon").

Whatever the case, the spatial light modulator 120 is controlled by the computer 160 to display different patterns.

These patterns allow here the spatial light modulator 120 to pass only some of the light rays emitted by the transmitter 110.

Two particular patterns, including a first checker pattern 121 and a second random pattern 122, are respectively shown in Figures 2 and 3 as illustrative examples.

After being reflected or having passed through the spatial light modulator 120, the light beam then has characteristics different from those which it presented upstream of this spatial light modulator 120. It is notably understood that the characteristics of the light beam differ in function of the pattern 121, 122 presented by the spatial light modulator 120.

It is then expected, in the path of this light beam, illumination optics 130 which is adapted to focus the light beam.

Here, this illumination optic 130 is formed of a succession of optical lenses.

It makes it possible to focus the light beam in a mean direction of illumination, in a limited area. In the remainder of this disclosure, this zone will be designated by the expression "transmission field of the transmitter 110". The emitter 110, the spatial light modulator 120 and the illumination optics 130 are then placed in the passenger compartment of the motor vehicle 1 in such a way that this emission field is directed into the zone situated opposite screw of the electronic control panel 2, so as to illuminate the hand 11 of the driver 10 when it is located in this area.

When the light beam illuminates the interior of the passenger compartment of the vehicle, and in particular the hand 11 of the conductor 10, part of this beam is reflected by these different elements in the direction of the photodiode 150.

To optimize the detection of this beam reflected by the photodiode 150, there is provided a concentration optic 140 which is adapted to focus the light towards the photodiode 150.

Here, this concentration optics 140 is formed of a succession of optical lenses. It is located in such a way that its optical axis merges with that of the photodiode 150.

In the remainder of this disclosure, the area of the passenger compartment seen by the photodiode 150 will be designated by the expression "field of reception of the photodiode 150".

The photodiode 150 and the concentrating optics 140 will then be placed in the passenger compartment of the motor vehicle 1 in such a way that this reception field is directed into the zone situated opposite the central electronic console 2, so as to be able to detect the hand 11 of the driver 10 when it is placed in this zone.

The emitting field of the emitter 110 and the receiving field of the photodiode 150 are more precisely oriented so that they intersect in the area opposite the central electronic console 2, to immediate proximity to it.

The computer 160 is connected to the photodiode 150, so as to receive the output signal S2.

As shown in FIG. 2, in order to be able to control the transmitter 110 by sending it control signals S1, to control the display of patterns 121, 122 by the spatial light modulator 120 by sending it signals S5, and receive the output signals S2, the computer 160 includes a processor 162 connected to the transmitter 110, the spatial light modulator 120 and the photodiode 150, and a storage unit, here a memory 161 no -volatile rewritable.

The memory 161 stores data used in the context of the method described below.

It stores in particular a first database register, which comprises several records each associating, with a particular gesturing element, a command instruction of a function of the central electronic console 2.

It also stores a second database register, which comprises several recordings each associating, with a pattern 121, 122 that the spatial light modulator 120 can exhibit, a reference signal S3. This reference signal S3 corresponds to the output signal S2 that would be emitted by the photodiode 150 if, on the one hand, the spatial light modulator 120 had the pattern 121, 122 recorded, and if, on the other hand, no passenger was present in the motor vehicle.

The memory 161 also stores a computer application, consisting of computer programs comprising instructions whose execution by the processor 162 allows the implementation by the computer 160 of the method described below.

Among these computer programs, the memory 161 stores a detection software adapted to determine the position and / or the displacement and / or the shape of the hand 11 as a function of each output signal S2 received.

Here, it also stores an interpretation software adapted to generate a control command of a function of the central electronic console 2 as a function of the position and / or the displacement and / or the shape of the hand 11.

The gesture control method of the central electronic console 2 is then implemented in two successive operations, a first operation of which is performed by the detection software and which consists in determining the position and / or the displacement and / or the form hand 11, then a second operation that is operated by the interpretation software and which consists in interpreting this information to deduce a command instruction.

The first operation takes place in several steps illustrated in Figure 3.

The first step is for the computer 160 to send a control signal S5 to the spatial light modulator 120 so that it has a pattern 121, 122 determined.

This pattern can be chosen randomly.

Here, the first pattern 121, 122 to be displayed by the spatial light modulator 120 corresponds to the pattern recorded in the first record of the second database register.

The second step is for the computer 160 to send a control signal S1 to the transmitter 110 so that it emits a light pulse.

This light pulse will then have a high intensity and a very short duration, less than the nanosecond.

The light beam emitted by the emitter 110 will then be modulated by the spatial light modulator 120 and then concentrated by the illumination optics 130 in order to illuminate any object situated in the emission field of the emitter 110.

Any object situated in this emission field and in the reception field thus reflects a portion of the light beam towards the photodiode 150.

The third step then consists, for the photodiode 150, in transmitting an output signal S2 which is a function of the characteristics of the light received.

This output signal S2 is in the form of a simple temporal electrical signal, represented in FIG. 3, whose intensity variations are a function of the variations in light intensity received by the photodiode 150.

When it receives this output signal S2, the computer 160 looks in the database register for the reference signal S3 corresponding to the pattern 121, 122 used (it is recalled that this reference signal S3 corresponds to the output signal that would be transmitted by the photodiode in the absence of objects in the emission fields of the transmitter 110 and the reception of the photodiode 150).

Then, the computer 160 compares these output signals S2 and S3 reference.

If the output signal S2 is substantially identical to the reference signal S3, the computer 160 deduces that no object is visible by the photodiode 150. It then interrupts the detection method. The process can then be reset after a predetermined time, for example of the order of one second.

On the contrary, if the output signal S2 is substantially different from the reference signal S3, the computer 160 deduces that an object is visible by the photodiode 150, and it continues the detection method as follows.

The computer 160 then determines the difference between these two output signals S2 and reference S3, by means of a simple subtraction operation. This operation makes it possible to remove from the output signal S2 the components relating to the fixed objects of the passenger compartment, in order to keep only the components relating to the moving objects, typically the hand 11 of the driver 10.

This difference in signals forms a new signal called an entrenched signal S4. This cut-off signal S4 is then stored in the memory 161 of the computer 160. It has a weight (expressed in bits) which is reduced compared to the weight of the output signal S2, which makes it possible to reduce the space required in the memory 161 to store it. It can also be easily compressed.

This subtracted signal S4 illustrates the variations in intensity of the light that would be received by the photodiode 150 if only the hand 11 of the conductor 10 was in the emission fields of the transmitter 110 and the reception of the photodiode 150.

This retracted signal S4, if it allows to detect an object, alone is not sufficient to determine the position and shape of this object. This is the reason why the computer 160 will repeat the above three steps, by controlling the spatial light modulator 120 so that it presents patterns 121, 122 each time different, with a reduced time step. This time step may be of the order of a millisecond, or lower (depending on the capacity of the spatial light modulator 120 to quickly change pattern).

The computer 160 can thus repeat N times these three steps, so as to memorize N retracted signals S4. The number N will be at least greater than 10 so as to obtain sufficient information to determine the position and shape of the hand 11 of the driver 10.

The fourth and last step consists, for the computer 160, in processing the various signals cut off S4 in order to determine the position and the shape of the hand 11 of the driver.

To do this, he will be able to solve a system of N equations with N unknowns, whose coefficients will be derived from these N retracted signals S4, deconvolved by the transmitter pulse.

As shown in Figure 3, the detected shape of the hand 11 may be an approximate shape 12, consisting of one or more elements 13 of simple geometries. In fact, to obtain a better accuracy, that is to say a faithful image of the hand, it would be necessary to process a very large number of signals removed, which would require a significant computing power and would therefore increase the costs of the computer. computer.

Here, it will then be possible to model the hand 11 by three rectangles of variable height, width and orientation.

In summary, this first operation made it possible to determine the position and the shape of the hand 11 of the driver 10.

It can be repeated at regular intervals, for example every tenth of a second, so as to determine which movements the driver 10 performs with his hand 11.

The second operation, which is recalled that it consists in interpreting the shape, the position and the movements of the hand 11 of the driver to deduce a control instruction of a function of the central electronic console 2, can then be implemented. artwork.

During this second operation, the computer 160 searches in the first database register for a record associated with a gestural element of the type of the one performed by the driver 10. It then reads in this record a command of a function of the central electronic console 2 which is associated with this element of gestures. For example, it can be expected that when the driver imposes his deployed hand in front of the central electronic console 2 and maintains it in this position, the computer 160 deduces that it must control the ignition or extinction of the central electronic console 2.

It will thus be possible to store in the first database register a catalog of gestural elements each associated with a function of the central electronic console 2, which will make it possible to control the latter without touching it.

According to a not shown variant of the invention, it could be provided that the receiver comprises several photodiodes, for example distributed over several lines and over several columns. In this variant, the output signal will then comprise different components relating to the different photodiodes. This solution will thus provide more information to be processed to determine the position of the hand of the user.

Alternatively, it can be provided that the transmitter itself is a spatially structured light generator, provided that it is used in combination with a spatial light modulator.

Claims (15)

An object detection device (100), comprising: - a transmitter (110) which is adapted to emit a light beam; - a receiver (150) which is adapted to emit an output signal (S2) according to the characteristics of the light which it receives, and - a computer (160) which is adapted to process the output signal (S2) in order to detect an object (11), characterized in that it comprises, in the path of the light beam emitted by said emitter (110), a spatial light modulator (120), and that the receiver (150) has at least one photodiode. An object detection device (100) according to claim 1, wherein the spatial light modulator (120) comprises a micromirror array. The object detection device (100) according to claim 1, wherein the spatial light modulator (120) comprises at least one liquid crystal panel. An object detection device (100) according to claim 1, wherein the spatial light modulator (120) comprises a panel having a silicon reflective surface coated with a liquid crystal layer. 5. Object detection device (100) according to one of the preceding claims, wherein said transmitter (110) comprises a light emitting diode. An object detection device (100) according to one of the preceding claims, wherein there is provided an illumination optics (130) adapted to focus the light beam after it has been modulated by said spatial modulator. light (120). An object detecting device (100) according to one of the preceding claims, wherein there is provided concentration optics (140) adapted to focus the light to the receiver (150). 8. Gesture control system of an electronic device (2), comprising an object detection device (100) according to one of the preceding claims, wherein the computer (160) comprises a detection software adapted to determine the position and / or displacement and / or shape of said object (11) as a function of each output signal (S2) received, and interpretation software adapted to generate a control command of said electronic apparatus (2), according to position and / or displacement and / or shape of said object (11). 9. A gesture control system according to the preceding claim, wherein the computer (160) comprises a memory (161) in which is stored a database register, each record stores a command instruction associated with a particular position and / or a particular movement and / or a particular form of hand (11). A method of detecting objects by means of an object detection device (100) according to one of claims 1 to 7, comprising the steps of: a) controlling the spatial light modulator (120) in order to have a pattern (121, 122) determined, b) to control the emitter (110) to emit a light beam pulse, c) to detect, with said receiver (150), the light resulting from the reflection of the light beam on surrounding objects (11), and emitting an output signal (S2) according to the characteristics of the detected light, and d) processing, by means of said computer (160), the output signal ( S2) for detecting at least one of said objects (11). An object detection method according to claim 10, wherein steps a) to c) are repeated with different patterns (121, 122), and wherein, in step d), the calculator (160) processes each output signal (S2) to determine the position and / or displacement and / or shape of said object (11). 12. An object detection method according to claim 11, wherein in step d), an approximate shape (12) of said object (11) consisting of elements (13) of simple geometries is determined. 13. Object detection method according to one of claims 10 to 12, wherein in step d), it is expected to remove from each output signal (S2) a component (S3) associated with the fixed objects detected. . An object detection method according to claim 13, wherein said component (S3) is read from a memory (161) of the computer (160). 15. A method of gesture control of an electronic apparatus (2), by means of a gesture control system as defined in one of claims 8 and 9, wherein it is intended to implement a detection method. of objects according to one of claims 11 and 12, then it is expected that the computer (160) interprets the position and / or the displacement and / or the shape of said object (11) to deduce an instruction controlling said electronic apparatus (2).