FR3036181B1 - MOTOR VEHICLE EQUIPPED WITH TELEDETECTORS BY LASER. - Google Patents

Abstract

The invention relates to a motor vehicle (1) comprising a chassis (10), front and rear wheels (20, 25) resting on the ground, and means for measuring a pitch angle of the chassis relative to the ground. According to the invention, the measuring means comprise: - a front LIDAR sensor (30) which is fixed to the front of the chassis and which is oriented towards the front, and - a rear LIDAR sensor (35) which is fixed to the rear of the chassis and which is facing backwards.

Description

MOTOR VEHICLE EQUIPPED WITH LASER TELEDETECTORS

Technical field to which the invention relates

The present invention generally relates to the steering assistance of motor vehicles.

It relates more particularly to a motor vehicle comprising a chassis suspended on front and rear wheels which rest on the ground, and means for determining a pitch angle of the chassis relative to the ground.

It also relates to a method for determining a pitch angle of a chassis of a motor vehicle as mentioned above.

Technological background

It is known to seek to determine the attitude of a motor vehicle in order, for example, to best control the acceleration or braking torque exerted on each wheel of the vehicle or to adjust the orientation of the headlights so that , when the vehicle is heavily loaded on the rear, the headlights do not dazzle by vehicles traveling in the opposite direction.

A first method to determine the attitude of the vehicle is to equip the latter with an inertial unit and to deduce the orientation of the vehicle in space.

This method, if it gives satisfactory results, only makes it possible to determine the orientation of the vehicle in a landmark. If the road is not horizontal, the results can not then determine the attitude of the vehicle relative to the road, except to know the orientation of the road in the land reference.

Another method is to equip the vehicle's dampers with sensors to measure the amplitude of expansion or compression of each damper, and, by comparing these amplitudes, to deduce the attitude of the vehicle.

This second method, however, provides unreliable results. It is understood that in the case where one of the wheels of the vehicle passes briefly in a hollow of the road, the attitude of the vehicle does not change substantially whereas, due to the relaxation of the corresponding damper, the calculation of the plate is affected by this hollow.

Finally, the common disadvantage of these two solutions is that they require the provision on the vehicle of measuring means specifically designed for determining the attitude of the vehicle. They are therefore both expensive to implement.

Object of the invention

In order to overcome the aforementioned drawbacks of the state of the art, the present invention proposes to determine the attitude, and in particular the pitch angle of the vehicle, by means of sensors already present on the vehicle, these sensors making it possible to perform functions other than determining the attitude of the vehicle.

More particularly, it is proposed according to the invention a motor vehicle as defined in the introduction, wherein said determining means comprise: a front sensor remote sensing light, which is fixed to the front of the chassis and which is oriented forward so as to measure a first front distance between the front sensor and a first front impact point on the ground, at the front of the motor vehicle, - a back light sensing remote sensor, which is attached to the rear of the chassis and which is directed rearwardly so as to measure a first rear distance between the rear sensor and a first rear impact point located on the ground, at the rear of the motor vehicle, and - a unit calculating the pitch angle according to the first distance before and / or the first distance back.

Thus, the two front and rear sensors, type LIDAR (acronym for the expression in English language "light detection and ranging") are used to determine the distance between each sensor and a point on the road.

These two sensors, which can also be used for other functions (obstacle detection, parking aid, etc.), then make it possible to calculate the pitch angle of the vehicle very reliably.

It is understood, for example, that if the distance measured at the front increases and the distance measured at the rear decreases, it can be deduced that the vehicle tends to lean backwards (for example because the user charges the trunk of the vehicle, or because it accelerates). Other advantageous and non-limiting characteristics of the motor vehicle according to the invention are as follows: the front and rear wheels defining, when they are aligned, a longitudinal direction, it is provided that said front sensor is adapted to measure a second front distance between the front sensor and a second front impact point distinct from the first front impact point, said first and second forward impact points being located on an axis parallel to said longitudinal direction, and said rear sensor is adapted measuring a second rear distance between the rear sensor and a second rear impact point distinct from the first rear impact point, said first and second rear impact points being located on an axis parallel to said longitudinal direction; said calculation unit comprises means for acquiring a first distance before reference and a first reference distance, means for calculating the difference between the first distance before and the first distance before reference, and / or the difference between the first rear distance and the first reference rear distance, and means for deducing the pitch angle of the chassis as a function of at least one of said gaps; - There are provided means for determining the temporal variation of each of said first distances forward and back, and means for deducing, according to said temporal variations, the shape of the ground at the front of the motor vehicle; the front sensor, or respectively the rear sensor, is adapted to measure another distance between the front sensor, or respectively the rear sensor, and another point of impact which is distinct from the first point of impact before, or respectively from the first rear impact point, and which is located therewith along an axis orthogonal to said longitudinal direction. The invention also proposes a method for determining a pitch angle of a chassis of a motor vehicle as mentioned above, comprising: a step of measuring a first front distance between the front sensor and a first d-point; front impact located on the ground, at the front of the motor vehicle, and a first rear distance between the rear sensor and a first rear impact point located on the ground, at the rear of the motor vehicle, and a step of deducing said pitch angle as a function of at least one of said first measured forward and reverse distances. Other advantageous and non-limiting features of the method according to the invention are the following: - it is provided, in the measuring step, to measure a second distance before between the front sensor and a second point of impact before distinct from the first forward impact point, and a second back distance between the rear sensor and a second rear impact point distinct from the first rear impact point, and, at the deduction step, deriving said pitch angle from at least one of the second measured forward and backward distances; it is intended to acquire a first distance before reference and a first reference distance, to calculate the difference between the first distance before and the first distance before reference, and the difference between the first distance back and the first reference distance back, and, in the deduction step, to deduce the pitch angle of the frame according to said deviations; - It is intended to determine the temporal variation of each of said first distances forward and backward, and to deduce from said temporal variations, the shape of the ground at the front of the motor vehicle; in the measuring step, it is provided to measure another distance between the front sensor, or respectively the rear sensor, and another point of impact which is distinct from the first point of impact before, or respectively from the first rear impact point, and which is located therewith on an axis orthogonal to said longitudinal direction, and then it is expected to calculate a roll angle of the chassis relative to the ground as a function, on the one hand, of the other measured distance and, on the other hand, of said first distance before or of said first rear distance.

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 side view of a motor vehicle according to the invention, shown on a flat road, with a zero pitch angle; - Figure 2 is a schematic side view of the motor vehicle of Figure 1, shown on a flat road, with a non-zero pitch angle; - Figure 3 is a schematic side view of the motor vehicle of Figure 1, shown with a pitch angle of zero, on a non-planar road; - Figure 4 is a schematic rear view of the motor vehicle of Figure 1, shown on a flat road, with a zero roll angle; - Figure 5 is a schematic rear view of the motor vehicle of Figure 1, shown on a flat road, with a non-zero roll angle.

In Figures 1 to 5, there is shown a motor vehicle 1. As shown in these figures, it is a car having four wheels, namely two front wheels 20 and two rear wheels 25.

Alternatively, it could be a motor vehicle comprising two, three or more wheels.

Conventionally, this motor vehicle 1 comprises a frame which supports including a motor, body elements and cabin elements.

It is said that the chassis 10 is suspended on the front and rear wheels 20, 25. It is indeed connected thereto by suspension and / or damping means, which improve the comfort of passengers and optimize the handling of the vehicle.

It is then understood that depending on the amplitude of depression or relaxation of each of the suspension and / or damping means, the attitude of the chassis 10 relative to the road is likely to vary. At this stage, it will be possible to define a reference (X, Y, Z) linked to the road, the X axis being directed along (or tangentially to) the direction of the road, towards the front, and the Z axis being directed orthogonally to the plane of the road, upwards.

When the front and rear wheels 20, 25 of the motor vehicle 1 are aligned in the X axis of the road, they together define a longitudinal direction parallel to the X axis. The transverse direction will be defined as being parallel to the X axis. Y axis.

It is also possible to define the reference plane 11 of the frame 10 as a plane passing through a point of the frame 10 (for example by its center of gravity) and which is parallel to the plane of the road when it is horizontal and the vehicle is stopped.

Then, the attitude of the frame 10 is defined by two angles called pitch angle a and roll angle β. The pitch angle α is defined as the angle formed between the reference plane 11 of the frame 10 and the plane of the road, about the Y axis (see Figure 2). The roll angle β is defined as the angle formed between the reference plane 11 of the frame 10 and the plane of the road, about the X axis (see Figure 5).

Here, the motor vehicle 1 then comprises means for determining the trim of the chassis 10 relative to the road on which the motor vehicle 1 evolves.

These determination means comprise, according to a particularly advantageous characteristic of the invention: a front sensor 30 of LIDAR type (acronym for the English expression "light detection and ranging", that is to say, remote sensing by light), which is fixed to the front of the frame 10 and which is oriented towards the front so as to measure a first distance before D1av between the front sensor 30 and a first point of impact before P1av located on the ground, in front of the motor vehicle 1, - a rear sensor 35 of the LIDAR type, which is fixed to the rear of the chassis 10 and which is directed towards the rear so as to measure a first rear distance D1ar between the rear sensor 35 and a first point rear impact P1ar located on the ground, behind the motor vehicle 1, and - a pitch angle calculation unit has a function of the first distance before D1av and the first rear distance D1ar.

In practice, the front and rear sensors 30, 35 are laser remote sensors which, taking into account the speed of light, are capable of measuring a distance as a function of the delay between the emission of a pulse by the sensor and the detection by the same sensor of a reflected pulse.

These front and rear sensors 30, 35 are directional, in that they aim at one or more particular points, called the point of impact, so that they make it possible to measure a very precise distance between each of these points and the sensor. .

Here, each sensor is designed to target several particular points, in order to determine several distances between the sensor and these points.

It could be envisaged that the sensor comprises a plurality of laser light emission cells and a plurality of reflected pulse detection cells.

However, it will be preferable here to use a single cell adapted to emit several pulses every second, associated with an angular scanning system for deflecting each pulse by a known angle ε, typically using mirrors which deviate the axis from emission and reception of light.

Two front and rear sensors 30, 35 adapted to measure distances D1av, D2av, D3av, D1ar, D2ar, D3ar between the sensor and distinct points P1av, P2av, P3av, P1ar, P2ar, P3ar distributed on one axis will thus be used here. parallel to the longitudinal direction.

Preferably, as illustrated in FIG. 1, each of these two front and rear sensors 30, 35 will be adapted to measure three distances D1av, D2av, D3av, D1ar, D2ar, D3ar between the sensor and three distinct points P1av, P2av , P3av, P1 ar, P2ar, P3ar distributed on an axis parallel to the longitudinal direction.

As shown in Figure 4, at least one of these two sensors, here the rear sensor 35, will be further adapted to measure at least two (here five) distances D1ar, D4ar, D5ar, D6ar, D7ar between the rear sensor And distinct points P1ar, P4ar, P5ar, P6ar, P7ar distributed on an axis parallel to the transverse direction. The aforementioned calculation unit is in turn designed to process the signals emitted by the front and rear sensors 30, 35 in order to determine in particular the pitch angle α of the chassis 10.

This calculation unit is here formed by the main computer of the motor vehicle. As a variant, it could be formed by a computer dedicated to determining the attitude of the vehicle, in which case this dedicated computer would be connected to the main computer to communicate with it.

In any case, the calculator includes a processor (CPU), a random access memory (RAM), a read only memory (ROM), analog-digital converters (A / D), and different input and output interfaces .

With its input interfaces, the computer is adapted to receive front and rear sensors 30, 35 signals D1av distances, D2av, D3av, D1 ar, D2ar, D3ar, D4ar, D5ar, D6ar, D7ar measured. Thanks to its analog-digital converters, the signals received by the computer are sampled in time steps and are digitized.

In its RAM, the computer thus continuously stores the distances D1av, D2av, D3av, D1ar, D2ar, D3ar, D4ar, D5ar, D6ar, D7ar measured at the last time step, as well as those measured at the previous time step.

The distances measured at the preceding time step will be denoted by Dlavot D2avost D3avgt, D1aret> D2argt, D3argt, D4argt, D5arot, D6argt, D7argt.

Thanks to a predetermined mapping on test bench and stored in its read-only memory, the computer is adapted to calculate different values, in particular the pitch angle a, the roll angle β and the profile of the road at the front. of the vehicle.

The calculator comprises for this purpose: - means for acquiring reference distances D1av0, D2av0, D3avo, D1aro, D2aro, D3ar0, D4aro, D5aro, D6aro, D7aro, - means for calculating the difference AD1av, AD2av, AD3av, AD1ar, AD2ar, AD3ar, AD4ar, AD5ar, AD6ar, AD7ar between each measured distance and each corresponding reference distance, and - means for deriving the pitch angle α and the roll angle β of the frame 10 according to said deviations.

It also comprises: means for determining the temporal variation of each of the measured distances, and deduction means, as a function of said temporal variations, of the shape of the ground at the front of the motor vehicle 1.

The operation of these various means will be described in detail later in this presentation.

Finally, thanks to its output interfaces, the computer is adapted to transmit output signals to the various components of the vehicle, for example to means for adjusting the orientation of the headlights, taking into account the angles of pitch and roll and of the shape of the calculated route.

In preliminary, the computer calibrates the two front and rear sensors 30, 35. This calibration operation can advantageously be performed by the manufacturer of the motor vehicle 1 at the end of the assembly line of the vehicle. It can also be operated regularly by the computer itself, when the vehicle is stationary on a flat and horizontal ground, in an open area.

Under these conditions illustrated in FIGS. 1 and 4, the computer acquires the distances before D1av, D2av, D3av measured by the front sensor 30 and the rear distances D1ar, D2ar, D3ar, D4ar, D5ar, D6ar and D7ar measured by the rear sensor. 35.

These different distances are then stored in the computer's read-only memory, and form reference distances D1av0, D2avo, D3avo, D1aro, D2aro, D3aro, D4aro, D5aro, D6aro, D7aro.

Subsequently, when the motor vehicle is used, the method implemented by the computer at each time step is as follows.

In a first step, the computer acquires the distances before D1av, D2av, D3av measured by the front sensor 30 and the rear distances D1ar, D2ar, D3ar, D4ar, D5ar, D6ar, D7ar measured by the rear sensor 35.

During a second step, the calculator calculates the difference AD1av, AD2av, AD3av, AD1ar, AD2ar, AD3ar, AD4ar, AD5ar, AD6ar, AD7ar between each measured distance and each corresponding reference distance, which can be to write :

In a third step, the computer deduces the pitch angle α of the frame 10 relative to the ground (see Figures 1 and 2).

In practice and considering that the ground is flat, the measurement of only two distances before D1av, D2av by the front sensor 30 or two rear distances D1ar, D2ar by the rear sensor 35 would have been sufficient to obtain the pitch angle a .

Indeed, and by way of example, it will be possible to obtain the pitch angle α of the chassis 10 with respect to the ground using the following mathematical formulas:

Remember that ε is the deflection angle between the two emitted rays to measure the distances D1av and D2av.

However, in order to obtain more precision, especially if the roll is not perfectly flat, this pitch angle a is here calculated according to several distances before and several rear distances.

For this, the calculation explained above (carried out considering only the distances before D1av, D2av) is repeated: - a first time considering the distances before D2av, D2av, then - a second time considering the distances back D1ar, D2ar then - a third time considering the rear distances D2ar, D3ar.

This gives four approximations of the pitch angle a. The pitch angle considered here is then equal to the average of these four approximations.

During a fourth step, the computer deduces from the measurements made the roll angle β of the chassis 10 relative to the ground (see FIGS. 4 and 5).

Here again, considering that the ground is flat, the measurement of only two rear distances D1ar, D6ar by the rear sensor 35 could be sufficient to obtain the roll angle β.

Indeed, we can then write:

with φ = arcos (D1aro / D6aro), and p = arcsin (D1ar. οοββ / D6ar).

However, here again, in order to obtain more precision, this angle of

roll is here calculated as a function of the set of rear distances D1ar, D4ar, D5ar, D6ar, D7ar-

For this, the previous calculation is repeated with several pairs of rear distances, so as to obtain several approximations of the roll angle, the average of these approximations providing the roll angle β considered.

During a fifth step, the computer determines the shape of the road at the front of the motor vehicle 1.

For this, the computer considers the last distances before and rear D1av, D1ar, D2av, D2ar, D3av, D3ar measured, as well as the distances before and back measured at the previous time step D1avSt, D1ar8t, D2avSt, D2ar5t, D3av5t, D3arst.

It then calculates the temporal variations 5D1av, δD1ar, 5D2av, 5D2ar, δD3av, δD3ar of these distances according to the following formulas:

In the situation shown in FIG. 3, where the vehicle is traveling on a flat road, except at the front of the vehicle, it will be understood that the temporal variations δD1ar, δD2ar, 3D3ar of the distances measured at the rear of the vehicle will remain substantially zero.

It is also understood that, due to the hollow of the road, the temporal variations 6D1av, 5D2av, δD3av measured distances to the front of the vehicle will be substantially different from zero.

Under these conditions, the computer can determine the profile of the road at the front of the vehicle, according to these variations.

The profile will then be taken into account to correct the pitch angle calculated during the third step.

It is understood that the calculation formula given above does not provide a reliable value of pitch angle a, because of the hollow on the road.

Claims (10)

A motor vehicle (1) having a chassis (10), front and rear wheels (20, 25) resting on the ground, and means (30, 35) for determining a pitch angle (a) of the chassis (10) relative to the ground, characterized in that said determining means (30, 35) comprise: - a front light remote sensor (30), which is fixed to the front of the frame (10) and which is oriented forwardly so as to measure a first front distance (D1av) between the front sensor (30) and a first front impact point (P1av) located on the ground, in front of the motor vehicle (1), - a sensor rear light sensing unit (35), which is attached to the rear of the chassis (10) and is rearwardly oriented to measure a first rear distance (D1ar) between the rear sensor (35) and a first rear impact point (P1ar) located on the ground, behind the motor vehicle (1), and - an English computing unit pitch (a) according to the first distance before (D1av) and / or the first distance back (D1ar). 2. Motor vehicle (1) according to the preceding claim, wherein, the front and rear wheels (20, 25) defining, when aligned, a longitudinal direction (X): - said front sensor (30) is adapted to measuring a second forward distance (D2av) between the front sensor (30) and a second front impact point (P2av) distinct from the first forward impact point (P1av), said first and second forward impact points (P1av, P2av) being located on an axis parallel to said longitudinal direction (X), and - said rear sensor (35) is adapted to measure a second rear distance (D2ar) between the rear sensor (35) and a second rear impact point (P2ar) distinct from the first rear impact point (P1ar), said first and second rear impact points (P1ar, P2ar) being located on an axis parallel to said longitudinal direction (X). 3. Motor vehicle (1) according to one of the preceding claims, wherein said computing unit comprises: - means for acquiring a first reference distance before reference (D1avo) and a first reference back distance ( D1ar0), - means for calculating the difference (AD1av) between the first distance before (D1av) and the first reference distance before reference (D1av0), and / or the difference (AD1ar) between the first back distance ( D1ar) and the first reference distance (D1aro), and - means for deducing the pitch angle (a) of the frame (10) according to at least one of said gaps (AD1av, AD1ar). 4. Motor vehicle (1) according to one of the preceding claims, wherein there is provided: - means for determining the temporal variation (0D1av, 5D1ar) of each of said first distances forward and backward (D1av, D1ar), and deduction means, according to said temporal variations (δD1av, 5D1ar), of the shape of the ground at the front of the motor vehicle (1). 5. Motor vehicle (1) according to one of the preceding claims, wherein, the front and rear wheels (20, 25) defining, when aligned, a longitudinal direction (X), the front sensor (30), or respectively the rear sensor (35), is adapted to measure another distance (D4ar) between the front sensor (30), or respectively the rear sensor (35), and another point of impact (P4ar) which is distinct from the first point of impact before (P1av), or respectively of the first point of rear impact (P1 ar), and which is located therewith on an axis orthogonal to said longitudinal direction (X). 6. A method of determining the attitude of a chassis (10) of a motor vehicle (1) according to one of the preceding claims, comprising: - a step of measuring a first distance before (D1av) between the front sensor (30) and a first front impact point (P1av) located on the ground, at the front of the motor vehicle (1), and a first rear distance (D1ar) between the rear sensor (35) and a first rear impact point (P1ar) located on the ground, at the rear of the motor vehicle (1), and - a step of deducing a pitch angle (a) of the chassis (10) relative to the ground, according to the first distance before and / or the first distance back (D1av, D1ar) measured. 7. Determination method according to claim 6, applied to a motor vehicle (1) as defined in claim 2, wherein it is provided: - at the measurement step, to measure a second distance before (D2av) between the front sensor (30) and a second front impact point (P2av) distinct from the first front impact point (P1av), and a second rear distance (D2ar) between the rear sensor (35) and a second end point rear impact (P2ar) distinct from the first rear impact point (P1ar), and - in the deduction step, to deduce said pitch angle (a) also as a function of the second distance before and / or the second distance back (D2av, D2ar) measured. 8. Determination method according to one of claims 6 and 7, applied to a motor vehicle (1) as defined in claim 3, wherein it is expected: - to acquire a first distance before reference (D1av0) and a first reference distance (D1aro), - calculating the difference (AD1av) between the first distance before (D1av) and the first reference distance before reference (D1avo), and the difference (AD1ar) between the first distance rearward (D1ar) and the first reference rear distance (D1aro), and - derive the pitch angle (a) of the frame (10) according to at least one of said gaps (AD1av, AD1ar). 9. Determination method according to one of claims 6 to 8, applied to a motor vehicle (1) as defined in claim 4, wherein it is intended: - to determine the temporal variation (δD1av, 6D1ar) of each said first distances forward and backward (D1av, D1ar), and - deriving from said temporal variations (5D1av, 5D1ar), the shape of the ground at the front of the motor vehicle (1). 10. Determination method according to one of claims 6 to 9, applied to a motor vehicle (1) as defined in claim 5, wherein it is provided: - in the measuring step, to measure another distance (D4ar) between the front sensor (30), or respectively the rear sensor (35), and another point of impact (P4ar) which is distinct from the first point of impact before (P1av), or respectively from the first point d rear impact (P1ar), which is located therewith along an axis orthogonal to said longitudinal direction (X), and - calculating a roll angle (β) of the chassis (10) relative to the ground in function, on the one hand, of said other distance (D4ar) measured and, on the other hand, of said first distance before (D1av) or said first rear distance (D1ar).