JP4709835B2 - Driving assistance system for interaction between mobile and infrastructure - Google Patents

Description

  The present invention relates generally to information and guide systems, also referred to as driving assistance systems for mobiles traveling on infrastructure, and more particularly to systems using magnetic fields.

  In the context of road safety, for example, a number of fatal accidents have been caused by vehicles falling off the road. Therefore, it is important to continue to recognize the position of the vehicle regardless of environmental or climatic conditions. The prevention of road dropout can be further enhanced if infrastructure information (signals, radius of curvature, warpage, etc.) is supplied to the vehicle.

  There are already many guidance and information transmission systems. Of these, the selection of the magnetic field detection system yields a number of advantages. This is because the magnetic properties of the material are hardly altered by external weather conditions such as rain, fog, and brightness. The communication system between the mobile body based on magnetism and the infrastructure is independent from the external environment in the shape of tunnels, valleys, etc., and is not affected.

  There are known information systems based on magnetic methods that use magnetic markings in the form of permanent magnets. In this case, the magnet generally serves only as a position reference. Their use to encrypt information may be limited. This is because the information is fixed and can only be corrected by replacing a magnet of one polarity with another magnet of a different polarity. Therefore, the cost of correcting information encrypted with a permanent element is high. The magnetic detection system provided in the vehicle needs to detect a magnetic field that decreases in proportion to the cube of the distance between the permanent magnet and the magnetic sensor. As a result, as the distance between the transmitter and the receiver increases, the magnetic field becomes very weak and the performance of the position system is degraded.

  The use of magnetic marks in the form of magnetic bands deposited on or in the infrastructure is an effective alternative. This is because the magnetic field is not inversely proportional to the third power as in the case of individual permanent magnets, but is inversely proportional to the square of the distance between the magnetic strip and the on-board sensor.

  US Pat. No. 6,289,269. B1 discloses a system for guiding vehicles on an infrastructure, comprising a continuous guide in the form of a magnetic strip applied on the surface of the infrastructure. A double and vertical magnetic sensor is used to measure the magnetic field of the magnetic band and the surrounding magnetic field at the bottom and to measure only the surrounding magnetic field at the top further away from the magnetic band. From the difference between these two measured magnetic fields, the position of the vehicle is derived. However, this method does not provide an accurate value for the position of the vehicle on the infrastructure. This is because the proposed dual sensor does not take into account changes in the surrounding magnetic field or the influence of the metal body. Furthermore, the magnetic strip is only used to guide the vehicle.

  The object of the present invention is an innovative driving assistance system, in particular comprising magnetic markings consisting of magnetizable particles deposited on or in the infrastructure, which particles are not expensive and are encrypted in this band. It is to propose a system that makes it possible to easily reprogram the structured data. The object of the invention relates not only to the infrastructure on or in which magnetic markings are formed, but also to a detection device for this driving assistance system.

For this purpose, the present invention is a driving assistance system for supplying information to vehicles traveling on infrastructure,
Magnetic markings formed on or in the infrastructure and suitable for encrypting information destined for vehicles, wherein the information can be changed;
A plurality of magnetic sensors mounted on the vehicle for detecting the total magnetic field including the magnetic field generated by the magnetic marking and generating a signal corresponding to the total magnetic field, and processing the corresponding signal, while the vehicle and the magnetic marking And a detection device comprising a processing unit adapted to determine a first distance between them and on the other hand to decrypt the information encrypted in the magnetic marking.

  This allows the magnetic field emitted by the magnetic marking to be used to calculate the position of the vehicle and notify the driver based on the encrypted information, and the information can change over time, so it is encrypted again Good.

  In one supplementary aspect, the magnetic marking is formed by the deposition of a marking complex for road signals, and one or more particle-shaped magnetic materials are added, the particles having a magnetic field that exceeds its retained magnetic excitation field. Can be subjected to residual magnetization, and the residual magnetization of these particles is adapted to encrypt information for the vehicle.

  Magnetic marking uses a known road signal method. By simply adding magnetic particles, the information can be encrypted and reprogrammed by applying a magnetic field to the particles that is greater than its holding excitation field.

  In an advantageous manner, at least two different types of magnetic material are present in the magnetic marker, each having a different holding magnetic excitation field, so that information for the vehicle can be encrypted at different security levels, most Important information is encrypted with a magnetic material having the highest retained magnetic excitation field.

  Thereby, different levels of information can be provided. Even if there is an error in programming of less important information, the more important information is not erased.

  Advantageously, the magnetic markers are deposited substantially continuously in the shape of a magnetic band, the information is encrypted in a substantially constant basic section along the length of the magnetic band, and each basic section has its own multi-directionality Has a magnetic field.

  In another aspect, the magnetic markers are deposited in the form of discontinuous magnetic bands formed at substantially constant basic intervals, the information is encrypted at substantially constant basic intervals, and each basic interval has its own multi-directional magnetic field. Have

  Thus, in these two modes, each section corresponds to a part of a band having changeable magnetization, and information of a plurality of bits can be encrypted.

  The multidirectional magnetic field includes at least a first component in a direction substantially perpendicular to the direction of the band and in the same plane.

  This first component can be used not only to encrypt information but also to define location criteria for mobiles on the infrastructure.

  The present invention is a driving assistance system for a vehicle on a road infrastructure, wherein the plurality of magnetic sensors include at least three magnetic sensors, and the processing unit erases the ambient magnetic field from the total magnetic field based on a corresponding signal from the magnetic sensor. It also relates to a system adapted to do so.

  This allows the driving assistance system to consider environmental noise in order to find the position of the vehicle in the infrastructure with higher accuracy.

  In a preferred embodiment, the driving assistance system includes at least a fourth magnetic sensor, and the processing unit considers a bias due to a change in the surrounding magnetic field, in particular a bias due to the distribution of the metal body, based on a corresponding signal from the magnetic sensor. Have been adapted.

  In another aspect, the magnetic sensor is aligned with a first axis that is substantially perpendicular to the axis of the vehicle, at least one auxiliary magnetic sensor is available, and is disposed on a second axis that is different from the first axis. Determines a second distance between the vehicle and the magnetic strip, and a processing unit determines the direction of the vehicle relative to the direction of travel on the infrastructure based on the first and second distances.

  The present invention is a detection device for the driving assistance system described above, which detects a total magnetic field including a magnetic field generated by a magnetic marking mounted on or in an infrastructure mounted on a vehicle, and corresponds to the total magnetic field. A plurality of magnetic sensors for generating signals and a processing unit adapted to process the corresponding signals and determine a first distance between the vehicle and the magnetic marker, the plurality of magnetic sensors comprising at least The processing unit also includes a three magnetic sensor, and the processing unit is also adapted to erase the ambient magnetic field from the total magnetic field based on the corresponding signal.

  In another aspect of the detection apparatus, the plurality of magnetic sensors include a fourth magnetic sensor, and the processing unit is biased by a change in the surrounding magnetic field, particularly by a distribution of the metal body, based on a corresponding signal from the magnetic sensor. Is adapted to take into account.

  In one supplementary aspect of the detection device, the processing unit is adapted to decrypt the information encrypted in the magnetic marking.

  The present invention comprises an infrastructure for the driver assistance system comprising magnetic markings formed on or in the infrastructure and adapted to encrypt information for vehicles traveling on the infrastructure. Magnetic markings are formed by the deposition of marking composites for road signals, when one or more particle-shaped magnetic materials are added and these particles are subjected to a magnetic field greater than their retained magnetic excitation field. The residual magnetization of the magnetic marking can also be related to an infrastructure adapted to encrypt the information for the vehicle.

  In an advantageous aspect of the infrastructure, at least two different types of magnetic material are in the magnetic marker, each having a different holding magnetic excitation field, so that information for the vehicle can be encrypted at different safety levels, The most important information is encrypted with the magnetic material having the highest retained magnetic excitation field.

  The present invention is a vehicle that can run on this infrastructure and is equipped with the detection device, which device determines at least a first distance between the vehicle and the magnetic marking and is encrypted in the magnetic marking. Also relates to vehicles used to decipher.

Finally, the invention relates to a vehicle traveling on an infrastructure comprising magnetic markings formed on or in the infrastructure and adapted to encrypt information for the vehicle, which is mounted on the vehicle and is magnetically marked. A method for assisting driving a vehicle having a detection device comprising: a plurality of magnetic sensors that detect a total magnetic field including a magnetic field generated by a plurality of magnetic sensors and generate a signal corresponding to the total magnetic field; and a processing unit for the corresponding signal. And
a) measuring the total magnetic field using a plurality of magnetic sensors;
b) using the processing unit to determine information encrypted during magnetic marking based on the corresponding signal;
c) using the processing unit to determine a first distance between the vehicle and the magnetic marker based on the corresponding signal;
d) transmitting the encrypted information and the first distance to a module forming an interface with the driver of the vehicle.

  Other features and advantages of the present invention will become apparent from the following description. This description is purely exemplary.

  A magnetic marking and driving assistance system according to the present invention is shown in the schematic diagram of FIG.

  A vehicle 20 is traveling on the infrastructure represented by the road 10 indicated by a dotted line in FIG. The term “road infrastructure” refers to all the roadways in the network that are used for the movement of mobiles. These include, of course, roads and may include small networks such as industrial areas and traffic paths in buildings. A magnetic marking, shown in the form of a continuous magnetic strip 30, is deposited in the center of the road 10. This magnetic band is formed by a sequence of sections (31, 32) having unique magnetic fields with different characteristics. The magnetic marking may take the form of a magnetic strip comprising a sequence of discrete sections each having a unique magnetic field with different characteristics. As will be explained below, the different magnetic field sequences make it possible to encrypt various important information along the magnetic marking. In the front part of the vehicle 20, on the one hand, the position of the vehicle 20 relative to the infrastructure 10 is calculated by calculating the position of the vehicle 20 with respect to the magnetic band 30. A set of in-vehicle magnetic sensors 33 is arranged to read

  In the schematic view of FIG. 1, the magnetic marking is arranged at the center of the lane 10 on which the vehicle 20 travels. In this case, the ideal position of the vehicle corresponds to the horizontal distance between the main axis of the vehicle 20 and the magnetic strip 30 being zero. However, it is also anticipated that the band is arranged, for example, on the white line next to the road or at another position off the center position in FIG. In the remainder of this description, it is assumed that the magnetic strip is in the center position for ease of explanation.

  FIG. 2 shows a diagram of an embodiment of the detection device used in the driving assistance system of the present invention. The device includes a detection unit including a support unit 60 attached to a vehicle (not shown). The support 60 is preferably placed in a direction perpendicular to the main axis of the vehicle. The main shaft of the vehicle is placed in the moving direction of the vehicle. The support 60 comprises at least three in-vehicle magnetic sensors 45, which are arranged, for example, under the vehicle, and the height between the support 60 and the magnetic marking represented here in the form of a magnetic band 40. The length h is several tens of centimeters. The height is preferably about 20-30 cm to allow reading of a magnetic field of sufficient amplitude and this amplitude varies according to the square of the distance between the magnetic strip and the sensor. The magnetic sensor 45 is aligned on the support 60 and connected to the processing unit 50 included in the detection device. This processing unit 50 analyzes the signal of the magnetic sensor 45 and not only reads and decrypts any information encrypted in the magnetic band, but in particular determines the distance between the magnetic band 40 and the vehicle. It is adapted to. The sensor 45 is preferably aligned on a straight line perpendicular to the vehicle main axis.

  The magnetic sensor can be housed, for example, in a bumper of a vehicle which is arranged at a height of about 25 cm from the road, ie the magnetic band. The magnetic sensor reads the entire magnetic field. The magnetic sensor must be able to measure a very weak magnetic field under high speed (vehicle speed), so it is necessary to select a high sensitivity sensor with low noise and fast response time. The magnetic sensor must be able to be operated by a power source provided at a voltage that can be used in the vehicle, and needs to have low power consumption. Known magnetic sensors such as Hall effect sensors and magnetoresistive sensors have these characteristics. A current loop sensor can also be used.

Table 1 below is an example of various types of features of known sensors.

  The sensor may be capable of detecting direction indication, in other words, the direction of a magnetic field having a non-zero component in a direction other than a direction parallel or perpendicular to the magnetic band.

  The distance determined by the processing unit 50 is transmitted to the module 55 along with the decrypted information, which is combined with the data, used with the decrypted information, transmitted to the driver at the vehicle location, read from the magnetic strip. It performs several functions such as sending various levels of information to the driver. As will be described later, the driver's attention is drawn to important information (such as approaching to a severe corner, deceleration, etc.) that the vehicle's axis has deviated excessively from the magnetic band or encrypted in the magnetic band. Can provide a warning message. For example, in order to draw the driver's attention, it is possible to display the position of the vehicle relative to the magnetic belt in the center of the driving lane, or to consider other appropriate display means, The driver knows the distance between the vehicle and the lane and can take corrective action as necessary.

  The number of sensors is a decisive factor for the accuracy of determining the distance between the vehicle and the infrastructure, as well as decoding the information recorded on the magnetic strip. As pointed out in the context of known inductive devices, the use of two sensors is insufficient in view of the effects of nearby environmental noise and metal bodies. This is because the signal from the magnetic sensor is particularly related to the total magnetic field incorporating the magnetic field from the magnetic band and the surrounding magnetic field (such as the earth's magnetic field). These magnetic fields are also affected by various nearby metal bodies.

  The driving assistance system according to the present invention includes at least three magnetic sensors together with the detection device, and considers an ambient magnetic field when processing signals from the sensors. In fact, the number of magnetic sensors is selected according to the desired accuracy of distance measurement between the vehicle and the magnetic strip. By using the fourth magnetic sensor, changes in the surrounding magnetic field due to the influence of various metal bodies in the vicinity can be considered on the signal value from the magnetic sensor.

  In order to estimate the position of the vehicle relative to the magnetic strip installed on the infrastructure, the processing unit compares the response from each sensor with a standard response, which is specifically magnetized at a predetermined position. Approximate the theoretical response that the sensor would provide in the presence of the total magnetic field due to the presence of the band and ambient magnetic field. The standard response parameter of the sensor that best fits the measurement is considered to be the result of the process.

式中、
ａは、周囲磁界、特に地球磁場を考慮する定数であり、
ｂは、例えば近傍の金属ボディによる周囲磁界の変化によるバイアスであり、
ｃは、帯の１方向磁界の振幅である。この振幅は、車両向けの情報の暗号化を可能にする。従ってこれを決定することによって、ある基本区間から次の区間（図１の３１及び３２とマークされた位置）への変化から、帯の中に暗号化された情報を推定できる。
ｘｉは、支持部に沿った異なるセンサの位置である。
ｈは、磁気帯とセンサとの間の垂直方向の距離であり、
ｄは、磁気センサのセットの中心と磁気帯との間の水平方向に測定された距離である。この距離を知ることで、車両の連続的な位置を知ることが可能になる。 To illustrate distance estimation, the magnetic markings formed on or in the infrastructure are in the form of a continuous magnetic band, producing a unidirectional magnetic field that is coplanar and perpendicular to the direction of the band. Assume. In addition, the sensors are considered to be aligned on a support perpendicular to the vehicle's main axis. Then, the magnetic field is expressed by the following equation.

Where
a is a constant that takes into account the ambient magnetic field, especially the earth's magnetic field,
For example, b is a bias due to a change in the surrounding magnetic field due to a nearby metal body,
c is the amplitude of the unidirectional magnetic field of the band. This amplitude enables the encryption of information for the vehicle. Therefore, by determining this, the information encrypted in the band can be estimated from the change from one basic section to the next section (positions marked 31 and 32 in FIG. 1).
xi is the position of the different sensor along the support.
h is the vertical distance between the magnetic strip and the sensor;
d is the distance measured in the horizontal direction between the center of the set of magnetic sensors and the magnetic strip. Knowing this distance makes it possible to know the continuous position of the vehicle.

  In the following method description, it is assumed that the number of magnetic sensors is 5, they are equally spaced, and the distance d is the horizontal distance between the center sensor (third sensor) and the magnetic strip. .

Thereafter, supplementary functions gxi and hxi are introduced on the basis of a value f (xi, d) described as fxi, and the ambient magnetic field and various unknown constants a and b due to the change are deleted from the equation (1).
gxi = fxi + 1−fxi, which is based on the value of fxi.
Where iε [1,4] and a is deleted.
hxi = gxi + 1−gxi, which is based on the value of gxi.
Where iε [1,3] and b is deleted.

  These fxi, gxi, and hxi values are a function of the distance d to be estimated and the amplitude c of the magnetic field that encrypts the information in the band, forming the standard response values described above. Yes. The shape of the magnetic field (1) and the values of gxi and hxi indicate that a system with at least three sensors is effective when it is desired to eliminate the surrounding magnetic field (parameter a) and the presence of a nearby metal body If it is desired to consider (parameter b), it clearly shows that the fourth sensor is effective. This is because it is necessary to have as many independent measurements as at least the number of different parameters.

It is also possible to introduce values Mgxi and Mhxi calculated according to the same relationship as the values gxi, hxi and kxi based on the measured value Mfxi of the magnetic field measured by the magnetic sensor at the position xi. As a result, the following equation is obtained.
Mgxi = Mfxi + 1−Mfxi, based on the measured value Mfxi.
Mhxi = Mhxi + 1−Mhxi, based on the value Mgxi.

  The least square method can be applied to the above various values to estimate the position of the band as accurately as possible.

Let Jf be the least squares function of the value fxi.

  This function Jf depends in particular on d and c. The minimum value can be used to obtain an estimate of d and c based on measurements from five magnetic sensors. The least squares method is applied to the values of gxi and hxi and can eliminate parameters that are unnecessary to estimate d and c, in other words a and b.

ｈｘｉ＝ｃ．ｈ’ｘｉ、ｉ∈［１，３］を導入し、ｈ’ｘｉはｄだけの関数であるとすると、方程式（３）は次式のようになる。

ここで方程式（３’）中のｃは定数である。 As a function known as a double estimation function, the least square method is applied to the standard response value hxi, and the following equation is established.

hxi = c. If h′xi, i∈ [1,3] is introduced, and h′xi is a function of only d, equation (3) becomes as follows.

Here, c in the equation (3 ′) is a constant.

は以下の新しい関係式を生成する。

Generates the following new relation:

  The estimation of c provides the information stored in the magnetic band and allows Jh to be a function of d only, the minimum value for each measurement Mfxi obtained from 5 sensors. It can be used to estimate the distance d.

  FIG. 3a shows a comparison between the distance d provided by the double estimation function Jh and the actual distance.

式中、方程式（４）中のｃは定数である。 For a function known as a single estimation function, the least squares method is applied to the standard response value gxi and b = 0, in other words, it is assumed that the ambient magnetic field does not change spatially. As a result, the following equation is established.

In the equation, c in the equation (4) is a constant.

は以下の新しい関係式を生成する。

ｃの推定は、磁気帯中に記憶された情報を提供し、Ｊｇをｄのみの関数にすることを可能にし、その最小値は、５個のセンサから得られた各測定値Ｍｆｘｉのための距離ｄの推定に使用できる。

Generates the following new relation:

The estimation of c provides information stored in the magnetic band and allows Jg to be a function of d only, the minimum value of which is for each measurement Mfxi obtained from 5 sensors. It can be used to estimate the distance d.

  FIG. 3b shows a comparison between the distance d provided by the single estimation function Jg and the actual distance.

  According to the test results, it is better to use the double estimation function to estimate the distance d between the magnetic band and the central sensor, and the error is ± 0.2 cm over the measurement range (−60 cm, 60 cm), There, five sensors were arranged 25 cm from the ground at a height of 25 cm in the lateral direction, and the measurement noise of each sensor was about 20% of the measurement dynamic range. In the case of the single estimation function, the error range is ± 5.0 cm because the change in the surrounding magnetic field is ignored.

  If a double estimation function is used, the driving assistance system and the detection device may have only four sensors. However, it is useful to have one spare sensor in case one of the sensors fails to operate. In one advantageous aspect of the present invention, the driving assistance system and the detection device may include a calibration system as shown in FIG. 4, which calibration system is for verifying the operational state of the magnetic sensor and by the sensor. It can be used to eliminate differences in the sensor response to the desired magnetic field based on the measured signal.

  This is because the vehicle position estimation described above does not take into account differences in sensor response. FIG. 4 shows five magnetic sensors numbered 61-65, which are aligned on an axis aligned in a direction perpendicular to the main axis of the vehicle. Each of the two electromagnets 71 and 72 with the induction coil is arranged on the one hand between the second and third sensors and on the other hand between the third and fourth sensors. Electromagnets are useful because they can generate a magnetic field of a specified value on demand. By measuring with different sensors, the processing unit can eliminate the difference in response between the sensors.

  If the sensors are separated from each other by a distance approximately equal to the sensor height h above the magnetic band and only the geomagnetic field can interfere with the measurement, another type of algorithm can be used to estimate the distance d, generated by the band Use the characteristics of the magnetic field, in particular the zero position located at a distance of height h on both sides of the maximum amplitude of the magnetic field, and the characteristic that the magnetic field changes slowly at distances beyond the zero position.

  In the first stage, the base level NB is determined by the median value of the measurement because the number of sensors far from the magnetic band is greater than the number of sensors close to the magnetic band.

  In the second stage, the sensor CN having the level N farthest from the median value NB, in other words the maximum | N−NB |, is detected, which corresponds to the sensor closest to the magnetic band.

  In the third stage, the sensor CA adjacent to the sensor CN having the level NA closest to N, in other words, the minimum value of | NA-N | is determined.

The distance d of the last band is estimated by the following equation based on the position xCN of the sensor CN and the position xCA of the sensor CA.
d = (xCN * (NA-NB) + xCA * (N-NB) / (N + NA-2 * NB)

The information c encrypted in the magnetic band is given by the following equation.
c = (N + NA-2 * NB)

  This simplified algorithm reduces the number of calculations required to determine the distance d with satisfactory accuracy, assuming that the measurement noise is sufficiently low.

  A test using a vehicle equipped with five sensors at a height of 15 cm above the ground was carried out on a track fitted with a magnetic band over a length of about 300 m. Using a simplification algorithm, when driving the distance d with an accuracy of about ± 1 mm over a range of +250 mm and -250 mm, especially over a magnetic band (the vehicle vibrates on both sides of the band) I was able to calculate.

  In the example of FIG. 4, if two sensors are included and the symmetry of the detection device can be utilized, only two electromagnets are sufficient, but this is due to the arrow between the sensor and the electromagnet in FIG. As shown, the first electromagnet 71 has an equivalent effect on the sensors 62 and 63 on the one hand and the sensors 61 and 64 on the other hand, whereas the second electromagnet 72 has the sensors 63 and 63 on the other hand. This is because it has an equivalent effect on the sensors 64 and 65 on the other hand. For example, taking sensor 63 as a reference, electromagnet 71 is activated in the first stage to modify sensor 62 and find the response of sensor 61 with respect to sensor 64. In the second stage, the electromagnet 72 is activated to modify the sensor 64 and consequently the sensor 61 using the relationship between these two sensors determined in the first stage, and the sensor modified in the first stage. The sensor 65 is corrected at 62. If the sensor signal does not change or does not change sufficiently when one or both electromagnets are activated, it is detected as a defective sensor.

  FIG. 5 shows a data acquisition sequence by the magnetic sensor shown in FIG. Data acquisition is synchronized. In other words, the five sensors measure the magnetic field simultaneously.

  The overall duration of the sequence is T0 and is divided into five time intervals. Each of the first four time intervals has a time T1, T1 is selected to satisfy 4T1 <T0 and provides a fifth time interval during which the processing unit performs processing and transfers data Selected to be able to.

  During normal operation, the first four time intervals are identical and the two electromagnets do not generate a magnetic field. During these four phases, the sensor records the magnetic field generated by magnetic bands deposited on or in the environment and infrastructure. The large amount of data acquired during each of these stages makes it possible to improve the signal / noise ratio and allow the calculation of the mean value of the magnetic field during the measurement.

  In operation during the calibration mode, two electromagnets do not generate a magnetic field in the first stage, one electromagnet generates a magnetic field in the second stage, two electromagnets do not generate a magnetic field in the third stage, and the fourth In the stage, the other electromagnet generates a magnetic field. During these four phases, the sensor records the magnetic field generated on the one hand by electromagnets and on the other hand by magnetic bands deposited on or in the environment and infrastructure. The change in sensor signal between the first and second stages can be used to determine the response of each sensor to the first activated electromagnet, and the change in sensor signal between the third and fourth stages is It can be used to determine the response of the sensor to the second activated electromagnet. The sensor can be calibrated according to the difference in measured values between one sensor and the other sensor. The large amount of data acquired during each of these stages makes it possible to improve the signal / noise ratio and allow the calculation of the mean value of the magnetic field during the measurement. Furthermore, the measurements during the first and third stages can be used directly to estimate the distance and information contained in the magnetic band for normal operation.

  If the bias due to the metal body and the bias due to the inherent noise of the magnetic sensor are considered simultaneously, a double estimation function can be used for the vertical unidirectional magnetic field in the above example, and the sensor is 25 cm from the ground at a distance of 25 cm. In this case, the distance is estimated to have an accuracy of 0.2 cm over a range of “−50 cm, 50 cm” and to an accuracy of 0.4 cm over a range of “−60 cm, 60 cm”.

  A calibration system can also be used to continuously check whether all sensors are operating normally. If necessary, when one of the sensors is defective (eg according to criteria programmed in the processing unit), the processing unit invalidates it and / or stops taking into account the measured magnetic field, Avoid miscalculating distances and / or reading encrypted information. The system with five sensors described above, in conjunction with the detection device, allows the driving assistance system to operate continuously even if one of the sensors is disabled as a result of a failure. To do.

  One variant of the driving assistance system and the detection device comprises the introduction of one or more magnetic sensors, which are aligned offset from the above sensors on a second support perpendicular to the main axis of the vehicle. . Additional sensors can be aligned on the rear bumper of the vehicle, for example. In this way, the previously calculated distance knowledge can be used in combination with the second horizontal distance knowledge between the additional sensor and the magnetic strip to determine the orientation of the vehicle axis relative to the road. . This information can be very useful for anti-skid control, for example.

  As shown in FIG. 2, the position data (distance d) and the data on the magnetization of the magnetic band (the amplitude of the magnetic field c enabling the encryption of information) are then formatted, in particular the position and encryption Useful information about the data is transmitted to the module intended to supply the vehicle.

  The magnetic markings deposited on or in the infrastructure in this way define the vehicle's location reference in the infrastructure and also act as an information carrier.

  The material used to form the magnetic marking is what is called a hard magnetic material. In these materials, the magnetization curve has a hysteresis cycle as shown in FIG. 6, and is characterized by the value of the residual magnetic field Br and the value of the coercive magnetic excitation magnetic field Hc. Hard magnetic materials are magnetized by applying an external excitation magnetic field to them. When the application of the excitation magnetic field is stopped, the magnetization of the material becomes equal to the residual magnetic field Br. The value of this magnetic field Br must be sufficient to be detected by a vehicle sensor. The value of the magnetic field Br can be changed by applying a different magnetic field, but it needs to be larger than the holding magnetic field Hc. In order to ensure that the magnetic field generated at a distance of 1 m is properly detected by current conventional sensors, the remanent magnetization Br must be greater than 1000 Gauss.

  The hard magnetic material may be provided in particle form, particularly in the form of powder, beads or chips.

  The size of the particles may vary between a few nanometers and 1 or 2 millimeters or more. The holding magnetic field Hc may vary from about 1 to 20000 Oersted, preferably 5 to 5000 Oersted. Particles with a coercive field less than 5 Oersteds can be demagnetized too easily, while particles with coercivity greater than 5000 Oersteds require very special and expensive equipment for their magnetization.

Preferably, the hard magnetic material is a stable oxide magnetic material class, also known as magnetic ferrite. The most commonly used are barium hexaferrite BaFe ₁₂ O ₁₉ and strontium hexaferrite SrFe ₁₂ O ₁₉ . Strontium and barium can be replaced with lead. Other, for example, hard magnetic materials such as magnetite _Fe 30 _{O 4} and cubic ferrite can take extended needle shape such as gamma ferric oxide _gamma-Fe 2 _{O 3} can also be used. These magnetic ferrites are produced in large quantities and are stable when stored outdoors.

  Other hard magnetic materials that can be used are chromium dioxide and alnico (aluminum-nickel-cobalt-iron alloy), iron-based alloys, iron-carbon, iron-cobalt, iron-cobalt-chromium, iron-cobalt-molybdenum, copper -Alloys such as nickel-iron, manganese-aluminum, cobalt-platinum, etc.

  The residual magnetic flux density of the hard magnetic material does not have directivity in the particle shape. This format facilitates incorporation into road and highway marking compounds. The compounds intended for these road signals may be hot melt materials that are deposited in the form of a molten material. Also known are low-temperature coating substances which are applied in the form of polymer preparation solutions, for example of monomers which can be polymerised. Also known are road and highway marking paints, which are generally resin or water-based polymer dispersions melted in organic solvents, and generally contain various additives necessary to accelerate the slow drying speed of water-based paints. Has been. Similar to fluid composites, there is a known method of depositing shaped bands, which is made by preliminary band manufacture and rewinded when applied to the road. Thus, magnetic markings deposited on or in the infrastructure can take a variety of forms.

  These various types of composites generally include fillers and dyes.

  When the magnetic marking on the infrastructure is separate from the signal band and its visibility needs to be limited, a dye may optionally be added to the composite. A dye may be added to prevent the band from being completely visible to the human eye.

  The hard magnetic material incorporated in such a composite is a conventional device such as a spray device described in US Pat. Nos. 6,505,995 and 4,401,265 in the form of strips. Used to deposit on the infrastructure in a continuous or discontinuous manner. In this case, the magnetic marking of the infrastructure according to the invention takes the form of a continuous or discontinuous magnetic band. In the case of discontinuous magnetic bands, the marking compound is deposited at regular or non-constant intervals.

  For this purpose, the strip can be deposited in the infrastructure by providing a shallow recess, and the coating is masked by filling the recess with another material to increase the lifetime of the magnetic strip.

  The magnetic strip deposited in this way can serve as an information carrier by forming a continuous portion or base section of the strip with variable and multi-directional magnetization assigned to each portion. The portions or sections may be in contact with each other (continuously deposited bands) or not in contact (discontinuous bands). These sections may be distributed uniformly along the length of the magnetic strip as shown in the schematic diagram (reference numerals 31 and 32) in FIG. In one particular aspect, the base section comprises a length of 1 to 4 times the average height between its magnetic band and the onboard magnetic sensor, preferably 1 to 2 times the average height. It has.

  The change in magnetic field from one compartment to the next can involve a single change in direction in the case of a unidirectional magnetic field, regardless of whether the magnetic band is continuous or not. Allows a sequence of logical states "0" and "1" shown for binary encryption of information. Encryption can be more complex when multiple components are allowed in the magnetic field. The amplitude can be changed.

  The recording or correction of information is performed by applying an external magnetic field larger than the coercive force to leave residual magnetization or changing existing magnetization. This operation can be performed by passing a specific moving body on the belt. The holding force Hc of the hard magnetic material used must be sufficiently large so that the stray magnetic field (such as the earth's magnetic field) does not modify the encrypted information.

The information encrypted in this band may be of various types as follows.
Notes on infrastructure signals (speed limit, entry prohibition, etc.)
Infrastructure topographical data (tilt, corner radius of curvature, etc.),
Temporary information (road construction, course changes, etc.)
Commercial information (extra cultural events, nearby rest areas, fuel prices, nearby tourist attractions, etc.).

  This information obviously needs to change over time. However, the update intervals are not necessarily the same. Furthermore, not all information has the same importance, some are simply commercial or cultural, while other information is concerned with vehicle safety. It must be possible to rank information hierarchically.

  This is why it is useful to introduce a plurality of hard magnetic materials (at least two) into the same paint to enable encryption of different types of information with different safety levels. This ensures that the most important information (signals, terrain data, etc.) is encrypted with the hardest material (having the best Hc> 200 Oersted) and less important information (cultural events, fuel prices, etc.) Encrypted with a material that is less magnetic (smallest Hc> Oersted). A mobile body that can correct information with lower importance is a lightweight vehicle that can travel on the infrastructure at the same speed as other mobile bodies. Another advantage of layering information encryption is that very important information is large and has a specific purpose because it requires a metal body to generate a magnetic field that is larger than the coercivity of a very hard material. It can be corrected only by this vehicle. In this way, a very important message cannot be erased even if there is an error in programming a less important message.

  The system is financially independent using commercial messages recorded for vehicle users.

  Another advantage of the magnetic marking of the present invention is that if a partial degradation of the magnetic band occurs, the detection device only loses a limited bit of information. The driving assistance system therefore continues to operate even in such a case. In addition, for example, it is possible to consider providing redundancy for particularly important information among the information by repeating important information several times using a magnetic field having multi-directionality at each interval.

It is the schematic of the driving assistance system which concerns on this invention. It is a figure of the aspect of the detection apparatus containing the driving assistance system and magnetic sensor which concern on this invention. It is a figure which shows the difference of the double function which estimates the vehicle position with respect to a magnetic strip, and an actual position. It is a figure which shows the difference of the single function which estimates the vehicle position with respect to a magnetic belt, and an actual position. 1 is a schematic view of a calibration system according to the present invention. It is a figure which shows two sequences, ie, normal mode and calibration mode, of the data acquisition by the driving assistance system which concerns on this invention, and the magnetic sensor of a magnetic device. It is a figure which shows the typical magnetization curve of the magnetic ferrite used for the production | generation of the magnetic strip which concerns on this invention.

Claims (47)

A driving assistance system for supplying information to a vehicle (20) traveling on an infrastructure (19),
Magnetic markings formed on or in the infrastructure and suitable for encrypting information destined for the vehicle, wherein the information is changeable (30, 40);
A plurality of magnetic sensors (45) mounted on the vehicle for detecting a total magnetic field including a magnetic field generated by the magnetic marking and generating a corresponding signal of the total magnetic field, and processing the corresponding signal, A detection device comprising a processing unit (50) adapted to determine a first distance between a vehicle and the magnetic marking, and on the other hand to decrypt information encrypted on the magnetic marking. ,
The plurality of magnetic sensors include at least three magnetic sensors,
The driving assistance system, wherein the processing unit is adapted to erase an ambient magnetic field from the total magnetic field based on the corresponding signal from the magnetic sensor. The driving assistance system according to claim 1,
The magnetic marking is formed by the deposition of a marking complex for road signals, to which one or more kinds of particulate magnetic materials are added and these particles are remanently magnetized when subjected to a magnetic field exceeding their retained magnetic excitation field. A driving assistance system, wherein the residual magnetization of the particles is adapted to encrypt information for the vehicle. The driving assistance system according to claim 1 or 2,
There are at least two different magnetic materials in the magnetic marker, each of the magnetic materials having a different coercive magnetic excitation field, so that the information for the vehicle can be encrypted at different safety levels, the most important information A driving assistance system that is encrypted with a magnetic material having the highest retained magnetic excitation field. The driving assistance system according to any one of claims 1 to 3,
The magnetic markers are deposited substantially continuously in the shape of a magnetic band,
The information is encrypted in substantially constant basic sections (31, 32) along the length direction of the magnetic band, and each of the basic sections has a unique multidirectional magnetic field. The driving assistance system according to any one of claims 1 to 3,
Magnetic markers are deposited in the form of discontinuous magnetic bands formed at approximately constant basic intervals,
The information is encrypted in each of the basic sections, and each of the basic sections has a unique multidirectional magnetic field. The driving assistance system according to claim 4 or 5,
The basic section is a driving assistance system having a length of 1 to 2 times an average height between the magnetic belt and the on-vehicle magnetic sensor. The driving assistance system according to any one of claims 4 to 6,
The multi-directional magnetic field is a driving assistance system including at least a first component in a direction substantially perpendicular to the direction of the magnetic band and in the same plane. The driving assistance system according to any one of claims 2 to 7,
A driving assistance system in which the particles of magnetic material are bonded to a resin. The driving assistance system according to any one of claims 2 to 8,
The driving assistance system, wherein the magnetic material is magnetic ferrite. The driving assistance system according to any one of claims 2 to 9,
The driving assistance system, wherein the magnetic material is in the form of powder, beads, or chips having a diameter of 10 nm to 2 mm. The driving assistance system according to any one of claims 2 to 10,
The driving assist system, wherein the marking complex for road signals is preferably a water-based paint. The driving assistance system according to any one of claims 1 to 11 ,
Comprising at least a fourth magnetic sensor;
The processing unit is a driving assistance system adapted to consider a bias due to a change in the ambient magnetic field based on the corresponding signal from the magnetic sensor. The driving assistance system according to any one of claims 1 to 12 ,
The magnetic sensor is a driving assistance system aligned on a first axis (60) substantially perpendicular to the axis of the vehicle. The driving assistance system according to claim 13 ,
Comprising at least one auxiliary magnetic sensor located on a second axis different from the first axis;
An operation in which the processing unit determines a second distance between the vehicle and the magnetic belt, and determines a direction of the vehicle relative to a moving direction on the infrastructure based on the first and second distances. Auxiliary system. The driving assistance system according to claim 14 , wherein
At least one of the first and second distances, and the information encrypted in the magnetic band, is read by each of the magnetic sensors and is a function of the total magnetic field at each position (xi) of the magnetic sensor. A driving assistance system determined by the processing unit based on an estimation function comprising comparing values (Mfxi, Mgxi, Mhxi) on a least square basis, wherein the distance and information estimates are best suited for the read values . The driving assistance system according to claim 14 , wherein
At least one of the first and second distances (d) and the information (c) encrypted in the magnetic band are a value (Mfxi) read by each of the magnetic sensors,
NB, which is the median value of the read values;
N, which corresponds to a value farthest from the median, and is read by the sensor CN at the position xCN;
A driving assistance system that is calculated from the following formula based on the NA that corresponds to the value closest to the median and is read by the sensor CA at the position xCA.
d = (xCN * (NA-NB) + xCA * (N-NB) / (N + NA-2 * NB)
c = (N + NA-2 * NB) The driving assistance system according to any one of claims 1 to 16 ,
Further comprising a calibration device (71, 72) of the magnetic sensor, these devices can generate a supplementary magnetic field of a specific value,
A driving assistance system, wherein the processing unit is adapted to verify the operating state of the magnetic sensor and eliminate differences in the response of the magnetic sensor based on signals measured by the magnetic sensor. The driving assistance system according to claim 17 ,
The calibration device is a driving assistance system including an electromagnet. The driving assistance system according to any one of claims 1 to 18 ,
The driving assistance system, wherein the magnetic sensor is a magnetoresistive sensor, a Hall effect sensor, or a current loop sensor. A detection device for a driving assistance system according to any one of claims 1 to 19 ,
A plurality of magnetic sensors mounted on the vehicle (20) for detecting a total magnetic field including a magnetic field generated by a magnetic marking (30, 40) formed on or in an infrastructure and generating a corresponding signal of the total magnetic field (45)
A processing unit (50) adapted to process the correspondence signal and determine a first distance (d) between the vehicle and the magnetic marker;
The plurality of magnetic sensors includes at least three magnetic sensors,
The detection unit is adapted to erase an ambient magnetic field from the total magnetic field based on the corresponding signal. The detection device according to claim 20 ,
Comprising at least a fourth magnetic sensor;
The processing unit is a detection device adapted to take into account a bias due to a change in the ambient magnetic field based on a corresponding signal from the magnetic sensor. The detection device according to claim 20 or 21 ,
The magnetic sensor is a detection device aligned on a first axis (60) substantially perpendicular to the axis of the vehicle. The detection device according to any one of claims 20 to 22 ,
Comprising at least one auxiliary magnetic sensor located on a second axis different from the first axis;
Detection wherein the processing unit determines a second distance between the vehicle and the magnetic strip and determines a direction of the vehicle relative to a moving direction on the infrastructure based on the first and second distances apparatus. 24. The detection device according to claim 23 .
At least one of the first and second distances, and the information encrypted in the magnetic band, is read by each of the magnetic sensors and is a function of the total magnetic field at each position (xi) of the magnetic sensor. A detection device determined by the processing unit based on an estimation function comprising comparing values (Mfxi, Mgxi, Mhxi) with a least square criterion, wherein the distance and information estimates are best suited for the read values. 24. The detection device according to claim 23 .
At least one of the first and second distances (d) and the information (c) encrypted in the magnetic band are a value (Mfxi) read by each of the magnetic sensors,
NB, which is the median value of the read values;
N, which corresponds to a value farthest from the median, and is read by the sensor CN at the position xCN;
A detection device that is calculated from the following mathematical formula based on the NA that corresponds to the value closest to the median and is read by the sensor CA at the position xCA.
d = (xCN * (NA-NB) + xCA * (N-NB) / (N + NA-2 * NB)
c = (N + NA-2 * NB) The detection device according to any one of claims 20 to 25 ,
Further comprising a calibration device (71, 72) of the magnetic sensor, these devices can generate a supplementary magnetic field of a specific value,
A detection device adapted to verify the operating state of the magnetic sensor and to eliminate differences in the response of the magnetic sensor based on signals measured by the magnetic sensor. The detection device according to claim 26 .
The calibration device is a detection device including an electromagnet. The detection device according to any one of claims 20 to 27 ,
The magnetic sensor is a detection device that is a magnetoresistive sensor, a Hall effect sensor, or a current loop sensor. The detection device according to any one of claims 20 to 28 ,
The processing unit is a detection device adapted to decrypt information encrypted in the magnetic marking. A vehicle (20) capable of traveling on an infrastructure (10),
30. A magnetic marking (30, 40) formed on or in the infrastructure and adapted for encryption of information for vehicles, mounted with a detection device according to any of claims 20 to 29 ,
The apparatus determines at least a first distance (d) between the vehicle and the magnetic marking, and enables the decryption of information encrypted during the magnetic marking. A infrastructure (10) for the driving assistance system 19 according to any one of claims 1,
Magnetic markings (30, 40) formed on or in the infrastructure and adapted to encrypt information for vehicles (20) traveling on the infrastructure, the magnetic markings for road signals Formed by the deposition of a marking composite of one or more magnetic materials in the form of one or more particles added and these particles undergo remanent magnetization when subjected to a magnetic field greater than their retained magnetic excitation field (Hc) And the remanent magnetization of the magnetic marking is an infrastructure adapted to encrypt information for the vehicle. The infrastructure of claim 31 ,
There are at least two different magnetic materials in the magnetic marker, each of the magnetic materials having a different coercive magnetic excitation field, so that the information for the vehicle can be encrypted at different safety levels, the most important information An infrastructure that is encrypted with a magnetic material having the highest retained magnetic excitation field. The infrastructure according to claim 31 or 32 ,
The magnetic markers are deposited substantially continuously in the form of magnetic strips,
The information is encrypted in substantially constant basic sections (31, 32) along the length of the magnetic band, and each of these basic sections has its own multi-directional magnetic field. The infrastructure according to claim 31 or 32 ,
Magnetic markers are deposited in the form of discontinuous magnetic bands formed at approximately constant basic intervals,
The information is encrypted in each of the basic sections, and each of the basic sections has an independent multidirectional magnetic field. An infrastructure according to any of claims 31 to 34 ,
The infrastructure including the multi-directional magnetic field including at least a first component in a direction substantially perpendicular to a direction of the magnetic band and in a same plane. An infrastructure according to any of claims 31 to 35 ,
An infrastructure in which the magnetic material particles are bonded to a resin. An infrastructure according to any of claims 31 to 36 ,
An infrastructure in which the magnetic material is magnetic ferrite. An infrastructure according to any of claims 31 to 37 ,
The magnetic material is an infrastructure in the form of powder, beads, or chips having a diameter of 10 nm to 2 mm. In the infrastructure according to any of claims 31 to 38 ,
The marking complex for the road signal is an infrastructure, preferably a water-based paint. A vehicle (20) traveling on an infrastructure (10) with magnetic markings formed on or in the infrastructure and adapted to encrypt information for the vehicle, mounted on the vehicle and the magnetic A vehicle driving assistance method comprising: a detection device comprising: a plurality of magnetic sensors for detecting a total magnetic field including a magnetic field generated by marking and generating a corresponding signal of the total magnetic field; and a processing unit for the corresponding signal. There,
a) measuring the total magnetic field using a plurality of the magnetic sensors;
b) using the processing unit to determine information encrypted during the magnetic marking based on the corresponding signal;
c) using the processing unit to determine a first distance between the vehicle and the magnetic marker based on the corresponding signal;
a step of d) information encrypted and said first distance, and transmits to the module forming the interface with the driver of the vehicle, only including,
The plurality of magnetic sensors include at least three magnetic sensors,
A driving assistance method , wherein the processing unit is adapted to erase an ambient magnetic field from the total magnetic field based on the corresponding signal from the magnetic sensor . The driving assistance method according to claim 40 , wherein
Comprising at least a fourth magnetic sensor;
A driving assistance method, wherein the processing unit is adapted to consider a bias due to a change in the ambient magnetic field based on the corresponding signal from the magnetic sensor. The driving assistance method according to claim 40 or 41 ,
The driving assistance method, wherein the magnetic sensor is aligned on a first axis (60) substantially perpendicular to the axis of the vehicle. The driving assistance method according to claim 42 , wherein
Comprising at least one auxiliary magnetic sensor located on a second axis different from the first axis;
An operation in which the processing unit determines a second distance between the vehicle and the magnetic belt, and determines a direction of the vehicle relative to a moving direction on the infrastructure based on the first and second distances. Auxiliary method. The driving assistance method according to claim 43 ,
At least one of the first and second distances, and the information encrypted in the magnetic band, is read by each of the magnetic sensors and is a function of the total magnetic field at each position (xi) of the magnetic sensor. Driving assistance method determined by the processing unit on the basis of an estimation function comprising comparing values (Mfxi, Mgxi, Mhxi) on a least square basis, the distance and information estimates being most suitable for the read values . The driving assistance method according to claim 43 ,
At least one of the first and second distances (d) and the information (c) encrypted in the magnetic band are a value (Mfxi) read by each of the magnetic sensors,
NB, which is the median value of the read values;
N, which corresponds to a value farthest from the median, and is read by the sensor CN at the position xCN;
A driving assistance method that is calculated from the following formula based on the NA that corresponds to the value closest to the median and is read by the sensor CA at the position xCA.
d = (xCN * (NA-NB) + xCA * (N-NB) / (N + NA-2 * NB)
c = (N + NA-2 * NB) The driving assistance method according to any one of claims 40 to 45 ,
The magnetic marking is formed by the deposition of a marking composite for road signals, to which one or more particle-shaped magnetic materials are added and these particles are subjected to a magnetic field greater than their retained magnetic excitation field (Hc) A driving assistance method adapted to sometimes receive remanent magnetization, the remanent magnetization of the magnetic markings encrypting information for the vehicle. The driving assistance method according to claim 40 to 46 ,
There are at least two different magnetic materials in the magnetic marker, each of the magnetic materials having a different coercive magnetic excitation field, so that the information for the vehicle can be encrypted at different safety levels, the most important information The driving assistance method is encrypted with a magnetic material having the highest retained magnetic excitation magnetic field.

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