DE102019200422A1 - Method for estimating the position of an object with respect to a distance sensor of a motor vehicle - Google Patents

Abstract

The invention relates to a method (36) for estimating the position of an object (8) with respect to a distance sensor (6) of a motor vehicle (2), which has a transmitter (10) and a first receiver (14) and a second receiver (16) which are arranged at a first distance (56) on a first straight line (54). By means of the transmitter (10), a signal (12) is transmitted at a transmission time (26). A first receive signal (20) is received by means of the first receiver (14) at a first point in time (28), and a second receive signal (22) is received by means of the second receiver (16) at a second point in time (30). Half of the product (52) from the signal speed (50) and the time difference (48) between the first time (28) and the transmission time (26) is used as the distance (44) between the object (8) and the distance sensor (6) . The first solid angle (46) with respect to the first straight line (54) is the arc cosine from the quotient of the product of the signal speed (50) and the time difference (48) between the second point in time (30) and the first point in time (28) and the first distance (56). The invention further relates to a distance sensor (6) of a motor vehicle (2).

Description

The invention relates to a method for estimating the position of an object with respect to a distance sensor of a motor vehicle. The distance sensor has a transmitter and two receivers. The invention further relates to a distance sensor of a motor vehicle.

Motor vehicles usually have distance sensors, by means of which an approach to an object is detected. Such a distance sensor ensures, for example, when opening a side door that it is not brought against a curb or the like. Such a distance sensor is also used when parking the motor vehicle or maneuvering in comparatively narrow surroundings, so that the distance of the motor vehicle from any objects, such as other motor vehicles, can be determined relatively reliably.

Such distance sensors use cameras, for example, and the object is captured by evaluating a camera image. This usually requires a computationally intensive review of the images, which is why manufacturing costs are increased. The function of the distance sensor is also restricted in comparatively poor visibility conditions. An alternative to this is to use one transmitter and several receivers. The transmitter emits electromagnetic waves, for example radar waves, or ultrasound waves that are scattered and / or reflected on the object, if any. The retroreflected waves are recorded using the appropriate receiver. The distance between the object and each of the receivers is determined on the basis of a transit time between the transmission and reception of the waves or any changes in the signal shape due to the transit time. The exact position of the object with respect to all recipients is then determined by means of triangulation or trilateration.

For the exact determination of the position of the object, the exact position of the individual receivers with respect to the transmitter and also the position of the individual receivers relative to one another must be taken into account. Consequently, their position relative to one another must be determined comparatively precisely, and a new calibration of the distance sensor is required for each individual motor vehicle type or if the position of one of the receivers changes.

The triangulation or trilateration also requires a number of calculation steps, each of which requires at least one of the preceding calculation results. This increases the time required. However, since the position of the object is to be determined comparatively quickly and / or its position can change during operation, comparatively powerful hardware is required to determine the position of the object, which increases manufacturing costs. Furthermore, after the triangulation or trilateration is complete, the position of the object with respect to the distance sensor is in spherical coordinates. In order to increase comfort for a user of the motor vehicle, a conversion to a Cartesian representation is required, which requires further calculation steps.

The invention is based on the object of specifying a particularly suitable method for estimating the position of an object with respect to a distance sensor of a motor vehicle and a particularly suitable distance sensor of a motor vehicle, in particular reducing complexity and / or a number of calculation steps, and / or expediently Manufacturing costs are reduced.

With regard to the method, this object is achieved according to the invention by the features of claim 1 and with respect to the distance sensor by the features of claim 5. Advantageous further developments and refinements are the subject of the respective subclaims.

The method is used to estimate the position of an object with respect to a distance sensor of a motor vehicle. The method is preferably carried out by means of the distance sensor and this is therefore operated at least partially according to the method. The motor vehicle is, in particular, land-bound and expediently movable independently of a certain route. The motor vehicle is, for example, a commercial vehicle, such as a truck (truck) or bus. However, the motor vehicle is particularly preferably a passenger car (passenger car).

The distance sensor expediently serves to monitor a monitoring area and to infer an object in the monitoring area, that is to say in particular to monitor the presence of the object in the monitoring area. The object is stationary or movable, for example. The monitoring area is defined, for example, during production and has, for example, a certain extent, in particular 1 m, 2 m or 5 m. As an alternative to this, the monitoring area is predetermined on the basis of the physical conditions and / or a performance of the distance sensor.

The monitoring area is located, for example, inside the motor vehicle, so that an interior of the motor vehicle is monitored by means of the distance sensor. Here will For example, a user inside the motor vehicle is detected by means of the distance sensor. However, the monitoring area is particularly preferably located outside the motor vehicle, that is to say in an environment of the motor vehicle. In particular, the monitoring area is congruent with an adjustment area or is expediently around this by a certain distance, for example between 10 cm and 20 cm. The adjustment range is traversed by means of an adjustment part or can be traversed by means of the adjustment part. The adjustment part is, for example, a door, such as a side door or a tailgate. In particular, the adjustment part is driven by an electric motor.

The monitoring area is particularly preferably formed around the motor vehicle and is, for example, in a side region of the motor vehicle up to 1 m away from it. In other words, the area with a distance of up to 1 m next to the motor vehicle is monitored by means of the distance sensor. The monitoring area is particularly preferably arranged at least partially behind the motor vehicle and has, for example, an extent of up to 5 m or at least up to 2 m or suitably at least up to 1 m. Thus, when maneuvering the motor vehicle, any object located in a rear area is detected by means of the distance sensor. Depending on this, a driver of the motor vehicle is suitably warned. Alternatively or in combination with this, a front area of the motor vehicle is monitored by means of the distance sensor, in particular during a parking maneuver. Here, the maximum distance of the object to be detected, that is the maximum distance of the monitoring area from the motor vehicle, is in particular less than or equal to 5 m, 3 m, 2 m or 1 m. For example, the distance sensor is activated and consequently actuated when the speed of the motor vehicle is less than a certain speed, for example 10 km / h.

In a further alternative to this, the monitoring area reached, for example, up to 500 m, 400 m, 300 m, 200 m, 100 m, 80 m or 50 m in front of the motor vehicle. The distance sensor is suitably used to follow a motor vehicle in front, for example in an automatic distance control system. In a further alternative to this, the distance sensor monitors for a collision of the motor vehicle. The distance sensor is thus used at a comparatively high speed of the motor vehicle, but at least in the speed of the motor vehicle which is greater than 30 km / h. For example, the monitoring area is set depending on a speed of the motor vehicle.

The distance sensor has a transmitter and a first receiver as well as a second receiver. The transmitter is used to send out a signal. The two receivers are suitable for receiving the signal emitted by the transmitter, which was reflected and / or scattered on the object, and in particular are provided and set up. The two receivers are expediently identical to one another, so that identical parts can be used. The two receivers are arranged on a first straight line, which is thus determined by means of the two receivers. In particular, the straight line is parallel to an outer contour of the motor vehicle, in particular a bumper, in the area of the distance sensor. The first straight line is preferably arranged horizontally or vertically. The distance between the two receivers is equal to a first distance. The first distance is expediently constant and preferably between 1 mm and 10 cm, between 5 mm and 5 cm and for example essentially equal to 1 cm. For example, the first distance is adapted to the particular motor vehicle. The first distance is expediently the same for a specific type of motor vehicle. In summary, the two receivers are arranged at the first distance on the first straight line. In particular, the receivers are arranged with respect to the transmitter such that direct reception of the signal transmitted by the transmitter is not possible. For example, there is a shield between them.

The method provides that a signal is sent out by means of the transmitter at a time of transmission. The time of transmission is determined, for example, as a function of an external parameter, for example on the basis of an actuation of a switch by a user or upon activation of a specific function of the motor vehicle, for example upon activation of an adjustment drive and / or a reverse gear of the motor vehicle. The signal is expediently only sent out at the time of transmission. In other words, the transmission of the signal is started at the time of transmission, the signal preferably having a defined length in time. Subsequent to this, the sending is particularly stopped.

In a further step, a first receive signal is received at a first point in time by means of the first receiver, and a second receive signal is received at a second point in time by means of the second receiver. The two received signals have arisen due to the reflection and / or scattering of the signal on the object and are each received by the two receivers. The two points in time differ in particular, and thus also the two received signals. For example, an intensity of the received signals is due to an attenuation reduced compared to the signal. In summary, the receiver reflects and / or detects the signal reflected / scattered on the object as the respective received signal.

After the signal has been transmitted, the two receivers are expediently used to monitor the presence of the respective received signal within a respective time window, so that it can be received. In particular, the respective time window begins with the transmission of the signal, so that it cannot be incorrectly recorded directly. The duration of the respective time window is preferably limited, for example less than 5 seconds, 2 seconds or 1 second. Thus, only a comparatively short period of time is monitored for the presence of the received signal, so that hardware requirements are reduced.

The position of the object with respect to the distance sensor is determined on the basis of its distance and at least one first solid angle. In other words, spherical coordinates are used first of all. The first solid angle is the angle that another straight line includes with the first straight line. The further straight line is defined on the basis of the object and at least one of the receivers. In other words, the first and / or second receiver and the object lie on the further straight line. The distance of the object to the distance sensor is parallel to the further straight line.

Half of the product of the signal speed, that is the speed of the (scattered / reflected) signal, and the time difference between the first point in time and the time of transmission is used as the distance of the object to the distance sensor. In other words, the time difference between the first point in time and the transmission point in time, that is to say the transit time which the signal requires from being transmitted to being received by the first receiver, is first determined. In addition, this time difference is multiplied by the signal speed, that is to say the propagation speed of the signal, that is to say the speed of the signal. Any dispersion is neglected, or at least the speed of the fastest part of the signal is used as the signal speed. It is thus estimated that the object is located on an arc or a spherical surface around the distance sensor, in particular around the first receiver, and not on the surface of an ellipse. Comparatively simple formulas can thus be used, which reduces the number of calculation steps.

To determine the first solid angle, a quotient is first determined, the quotient of the product of the signal speed and the time difference between the second point in time and the first point in time and the first distance being used. In summary, the signal speed is first multiplied by the time difference between the second point in time and the first point in time. This value, i.e. the product, is divided by the first distance and thus the quotient is determined. The first solid angle is the arc cosine of this quotient. Thus, the approximation is used that the signal reflected on the object essentially has a flat front, which is why comparatively simple formulas can be used. This means that hardware expenditure is reduced, although the position of the object can be estimated within a comparatively short time.

In summary, the approximation is based on the assumption that the reflected / scattered signal has a flat front and that the object is located on a circular path or spherical surface with respect to the distance sensor. In particular due to the estimate, a deviation of the actual position of the object from the estimated less than 1 cm or 0.5 cm. Due to the reduced computing steps, no comparatively expensive hardware is required, which can carry out comparatively many computing operations in a short period of time. Manufacturing costs are thus reduced due to the method.

For example, the distance of the object to the distance sensor and / or the first solid angle is calculated directly, in particular using the analytical functions. Alternatively, an optimization process is used. Adjustment to different motor vehicles or motor vehicle types is thus simplified. In particular, when performing a calibration, the respective parameters are stored, expediently the first distance and / or the signal speed, so that they do not have to be specifically determined.

The method is carried out, for example, only once and in particular each time there is a certain user activity. As an alternative to this, the method is carried out repetitively in time, suitably at constant time intervals, the time interval being, for example, 1 second, 2 seconds or 5 seconds. The method is preferably repeated as long as a certain condition is fulfilled, for example a reverse gear of the motor vehicle is engaged. Security is thus increased.

For example, the first recipient is always the same of the two recipients used. In particular, the first receiver is the one of the two receivers that has the smallest distance from the transmitter. If, for example, the transmitter and one of the receivers are designed as an integrated unit, this receiver in particular is the first receiver. The first receiver is suitably the one of the two receivers in which the time interval between the time of reception of the received signal and the time of transmission is the smallest. In other words, the first receiver is redetermined each time the received signals are received. In this case, the respective received signal is received at a respective point in time by means of the two receivers and the time interval to the transmission point in time is determined at both points in time. The received signal, which has the smallest time interval from the time of transmission, that is, is used as the first received signal. The one of the two receivers by means of which the first received signal was received is used as the first receiver. Thus, the distance between the object and the distance sensor is estimated to be too small rather than the actual position of the object. As a result, security is increased.

The distance sensor particularly preferably has a third receiver which is arranged at a second distance from the first receiver. The first receiver and the third receiver are arranged on a common second straight line. For example, the second straight line is parallel to the first straight line. However, the second straight line is particularly preferably inclined with respect to the first straight line, so that a plane is determined by means of the two straight lines. The transmitter is preferably also arranged in the plane.

The position of the object with respect to the distance sensor is clearly determined using a second solid angle. The second solid angle is defined with respect to the second straight line. In other words, the position of the object with respect to the distance sensor is determined on the basis of the two solid angles and the distance, that is to say on the basis of spherical coordinates.

The second solid angle is the arc cosine of the quotient of the product of the signal speed and the time difference between the third point in time and the first point in time and the second distance. In other words, the product of the signal speed and the time difference between the third point in time and the first point in time is first determined. The signal speed is expediently the same as that used when estimating the first solid angle. This product is divided by the second distance and used as the quotient. The arc cosine is then applied to the quotient. The position of the object is thus clearly estimated on the basis of the third receiver, which increases security.

Alternatively, for example, the second solid angle is determined on the basis of a third straight line, the second receiver and the third receiver lying on the third straight line. The respective formulas are adapted accordingly.

The distance sensor preferably comprises further receivers, all of which lie, for example, in a common plane. In this way, a calculation is further simplified. Because of the additional receivers, reliability and security are increased. The distance from adjacent receivers is preferably constant, or these are at least at a constant distance from one of the adjacent receivers. In particular, the distance between adjacent receivers is between 1 mm and 5 cm. In this way, security is increased. The solid angle of the object is suitably determined with respect to a straight line, which is defined by means of the first receiver and the respective receiver. The first receiver is expediently the one in which the time interval between the reception of the received signal and the time of transmission is the smallest. It is thus possible to determine the solid angles in parallel and independently of one another in time, which reduces the time until the position of the object is finally estimated and thus increases security.

The signal is expediently a wave and is formed, for example, by means of a single peak or a specific wave form that deviates therefrom. The waveform is preferably uniquely determined. It is thus possible to check whether the received signals are based on the reflection / scattering of the signal or whether they have another origin. Security is thus increased. For this purpose, the received signals are preferably filtered by means of a suitable filter, so that only received signals with the corresponding waveform are processed further, so that the respective point in time is only determined on the basis of this.

The wave is, for example, a sound wave, which is preferably in the ultrasound range. Thus, the user is not disturbed by the operation of the transmitter. In a further alternative to this, electromagnetic waves are emitted during operation by means of the transmitter. These are, for example, light that is preferably not in the visible range. The transmitter is suitably a laser or comprises at least one laser. Alternatively radar waves or microwaves are emitted by means of the transmitter. If electromagnetic waves are emitted during operation by means of the transmitter, these can also be received by means of the receiver. However, if sound waves are emitted by the transmitter, the receivers are adapted accordingly.

The wavelength of the waves used is preferably many times smaller than the distance between the distance sensor and the object and / or the receiver. The wavelength is preferably less than 1/100, 1 / 1,000, 1 / 10,000 or 1 / 100,000 of the respective distance. In this way, any inaccuracies that are present due to the estimate are comparatively small, so that the estimated position of the object essentially corresponds to the actual one. In summary, the distance between the object and the distance sensor is much larger than the wavelength of the signal. Thus, based on the estimate, there are only comparatively minor inaccuracies, so that there is still certainty.

The distance sensor is part of a motor vehicle and has a transmitter and a first receiver as well as a second receiver. The two receivers are arranged at a first distance from one another on a first straight line. In other words, the first straight line is defined on the basis of the two receivers. In particular, the distance sensor is suitable, preferably provided and set up, for monitoring a monitoring area for the presence of an object. It is possible to send out a signal using the receiver. The signal here is, for example, a sound wave, such as an ultrasound wave, or an electromagnetic wave. In particular, the distance sensor is based on ultrasonic wave, LIDAR or radar technology. Alternatively, the transmitter is configured and tuned to emit light, for example. The receivers are suitable, in particular provided and set up, for receiving the signal emitted by the transmitter and reflected / scattered on an object. Suitably, the transmitter cannot send the signal directly to the respective receiver. In particular, there is a shield between them. The receivers are expediently identical to one another and are preferably mounted at a distance from one another in the installed state.

The distance sensor is operated according to a method for estimating the position of an object with respect to the distance sensor. At least this method is carried out during operation by means of the distance sensor. In particular, the distance sensor has a control unit which is suitable, expediently provided and set up to carry out the method. For this purpose, the control unit is preferably coupled to the transmitter and / or the receivers in terms of signal technology. The control unit includes, for example, a microchip that is programmable, for example. As an alternative to this, the control unit is at least partially formed by means of a user-specific circuit (ASIC).

The method provides that a signal is transmitted by means of the transmitter at a time of transmission. A first reception signal is received at a first time by means of the first receiver, and a second reception signal is received at a second time by means of the second receiver. The two received signals each originated from reflecting / scattering the signal on the object. Half of the product of the signal speed and the time difference between the first point in time and the time of transmission is used as the distance between the object and the distance sensor. The first solid angle of the object with respect to the first straight line is the arc cosine from the quotient of the product of the signal speed and the time difference between the second point in time and the first point in time and the first distance. This means that comparatively few calculation steps are required to estimate the position of the object, which is why comparatively inexpensive hardware can be used.

For example, the transmitter and / or the first receiver and / or the second receiver are arranged on a common printed circuit board. Thus, they are stabilized to each other, which increases robustness. In addition, it is possible to mount this as a common structural unit on the motor vehicle, which simplifies production. The control unit, if any, is preferably also connected to the printed circuit board or at least partially realized by means of the latter.

The distance sensor preferably comprises a third receiver, which is connected, for example, to the circuit board, if any. The third receiver and the first receiver are arranged on a second straight line, the distance between the third receiver and the first receiver being equal to a second distance. The second distance is, for example, between 1 mm and 5 cm. Using the three receivers, it is possible to determine two different solid angles and thus accurately estimate the position of the object with respect to the distance sensor. Security is thus increased. The distance sensor preferably has further receivers, which are all suitably arranged in a single plane. All receivers are expediently connected to the circuit board, which simplifies assembly. For example, the transmitter is also on the same level arranged. Thus, estimating the position of the object is further simplified.

For example, the two straight lines are parallel to each other. However, the two straight lines are particularly preferably inclined to one another. A right angle is preferably formed here between the two straight lines. In other words, the angle is 90 °, in particular a deviation of 10 °, 5 °, 2 ° or 0 ° is present. Due to the right angle, a comparatively unambiguous estimation of the position of the object with respect to the distance sensor is made possible, wherein the extension of the distance sensor, that is to say its structural size, can be comparatively small. Manufacturing is also simplified. Furthermore, a comparatively simple conversion of the spherical coordinates into Cartesian coordinates is made possible. In particular, a transformation of the individual angles is comparatively simple or not necessary. In particular, the transmitter is located on a straight line defined by the second and third receivers. As an alternative to this, the transmitter is spaced from the receivers and, for example, positioned arbitrarily with respect to them. In a further alternative, a rectangular structure is described by means of the transmitter and the three receivers. A comparatively compact distance sensor is thus provided, although a comparatively effective shielding of one another is still possible. In other words, it is avoided that the signal is detected directly by means of the receiver.

For example, the two distances differ from each other. However, the first distance is preferably equal to the second distance, the right angle preferably being formed between the first straight line and the second straight line. Alternatively, an angle of 60 ° is formed between them, for example, and an isosceles triangle is thus formed by means of the three receivers. The transmitter is preferably located in the center of the triangle. This results in a symmetrical construction of the distance sensor, so that the estimate is comparatively accurate.

For example, all receivers are spaced from the transmitter. However, it is particularly preferred that at least one of the receivers and the transmitter is designed as an integrated structural unit. Assembly is thus simplified. The integrated unit is preferably operated alternately in time as a transmitter or receiver. In particular, radar waves are emitted here. The same hardware can thus be used, in particular an identical resonant circuit and / or an antenna. Manufacturing costs are thus further reduced. The receiver, which forms the integrated structural unit with the transmitter, is preferably the first receiver, which increases the accuracy of the estimate of the distance of the object from the distance sensor.

The advantages and further developments mentioned in connection with the method can also be analogously transferred to the distance sensor and vice versa.

If a component is designated as the first, second, third, ... component, this is to be understood in particular only as a specific component. In particular, this does not mean that a certain number of such components are present.

• 1 schematisch ein Objekt und ein davon beabstandetes Kraftfahrzeug mit einem Abstandssensor, der einen Sender und mehrere Empfänger aufweist,
• 2 einen zeitlichen Verlauf eines mittels des Senders ausgesandten Signals sowie mehrerer Empfangssignale,
• 3 ein Verfahren zum Schätzen der Position des Objekts bezüglich des Abstandssensors des Kraftfahrzeugs,
• 4 schematisch vereinfacht die Entstehung zweiter Empfangssignale,
• 5 vergrößert einen Ausschnitt der 4, und
• 6 - 9 jeweils in einer Draufsicht schematisch vereinfacht weitere Ausgestaltungsformen des Abstandssensors

Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. In it show:

• 1 schematically an object and a motor vehicle spaced therefrom with a distance sensor which has a transmitter and a plurality of receivers,
• 2nd a time profile of a signal emitted by the transmitter and of a plurality of received signals,
• 3rd a method for estimating the position of the object with respect to the distance sensor of the motor vehicle,
• 4th schematically simplifies the creation of two received signals,
• 5 enlarges a section of the 4th , and
• 6 - 9 each in a top view schematically simplified further embodiments of the distance sensor

Corresponding parts are provided with the same reference symbols in all figures.

In 1 is schematically simplified a motor vehicle 2nd shown in a side view. The car 2nd has a total of four wheels 4th by means of which the motor vehicle 2nd gets up on a street. The car 2nd further includes a distance sensor 6 , by means of which a position of one of the motor vehicle 2nd spaced object 8th regarding the distance sensor 6 thus regarding the motor vehicle 2nd is determined. The distance sensor 6 when maneuvering the motor vehicle 2nd , for example when parking, activated, and by means of the distance sensor 6 is monitored whether the object 8th near the motor vehicle 2nd located. Also the position of the object 8th determined here. The position of the object 8th is from the distance sensor via a bus system, not shown 6 transmitted to a display in a field of vision of the driver of the motor vehicle 2nd is arranged. It is therefore for a driver of the motor vehicle 2nd possible the direction of travel of the motor vehicle 2nd adjust so that a collision with the object 8th is avoided. The distance of the object 8th is usually larger than 10 cm because the driver of the motor vehicle 2nd this controls and / or brakes accordingly.

The distance sensor 6 assigns a transmitter 10th on, by means of which a signal 12th can be sent. Here is the signal 12th an ultrasonic wave and thus a sound wave that lies in the area that is inaudible to humans. The distance sensor also points 6 a first recipient 14 , a second recipient 16 and a third recipient 18th on. By means of the first recipient 14 provided the signal 12th on the object 8th suitably reflected and / or scattered, a first received signal 20 received, thus the reflected / scattered signal 12th represents. Likewise, with a suitable idea, the second receiver 16 a second received signal 22 and by means of the third receiver 18th a third receive signal 24th receive. Here are the second and third reception signal 20 , 24th each due to a reflection / scattering of the signal 12th on the object 8th emerged.

The signal 12th is a pulse that occurs at a time of transmission 26 is sent out. So that's the signal 12th comparatively briefly. Because of the distance of the object 8th to the motor vehicle 2nd and thus to the distance sensor 6 becomes the first receive signal 20 at a first time 28 , the second received signal 22 at a second time 30th and the third receive signal 24th at a third point in time 32 receive. This time course in 2nd shown. Due to the weakening of the signal 12th through which the motor vehicle 2nd surrounding air, the intensity I is the received signal 20 , 22 , 24th decreased. Also due to the in 1 shown arrangement of the receiver 14 , 16 , 18th the times 28 , 30th , 32 temporally after this and successively from the transmission time 26 moved away. Due to a shielding of the distance sensor, not shown 6 it is not possible to use the receiver 14 , 16 , 18th the signal 12th to capture directly.

The distance sensor 6 also has a control unit 34 on, the signaling with all receivers 14 , 16 , 18th as well as the transmitter 10th is coupled. It is possible by means of the control unit 34 the individual recipients 14 , 16 , 18th read out and thus the individual received signal 20 , 20 , 24th to record and further process. The first recipient 14 as well as the transmitter 10th are designed as a common integrated unit. The same hardware is used here, namely a membrane that is coupled to an electromagnet. When the electromagnet is energized, the assembly thus acts as the transmitter 10th . If a voltage induced on the electromagnet due to a vibration of the membrane is tapped, the integrated unit acts as the first receiver 14 .

Using the control unit 34 becomes an in 3rd procedure shown 36 to estimate the position of the object 8th carried out. In a first step 38 is by means of the transmitter 10th at the time of transmission 26 the signal 12th sent out further from the object 8th to the motor vehicle 2nd is reflected and / or scattered back. In one go to the first step 38 subsequent second step 40 is by means of the receiver 14 , 16 , 18th the respective received signal 20 , 22 , 24th at the respective time 28 , 30th , 32 receive. Thus, by means of the first receiver 14 the first receive signal 20 at the first time 28 received, and by means of the second receiver 16 becomes the second received signal 22 at the second point in time 30th receive. Furthermore, by means of the third receiver 18th the third receive signal 24th at the third point in time 32 receive.

In a subsequent third step 42 becomes the distance 44 of the object 8th to the distance sensor 6 estimated the in 4th is shown. Also a first solid angle 46 estimated under which the object 8th regarding the distance sensor 6 takes place as in 4th and in 5 shown in sections. The first solid angle 46 here is with respect to the first straight line 54 Are defined.

As a distance 44 of the object 8th to the distance sensor 6 is the time difference first 48 between the first time 28 and the sending time 26 determined the in 2nd is shown. The time difference 48 becomes with the signal speed 50 of the signal 12th multiplied and as a product 52 used. The signal speed 50 is the speed of sound in air and essentially 1200 km / h. The product 52 is halved and as the distance 44 used.

To determine the first solid angle 46 first becomes a first straight line 54 determined on which the first recipient 14 and the second receiver 16 lie. In other words, the first straight line 54 by means of the first and second receiver 14 , 16 determined, and these are on the first straight line 54 . There is a first distance between them 56 formed, which is 1 cm in this example. The first distance 56 is in production in the control unit 34 deposited.

Furthermore, the product of the signal speed 50 and the time difference 48 between the second point in time 30th and the first time 28 formed and by the first distance 56 divided. In other words, the product by the first distance 56 granted. The first solid angle 46 under which the object 8th regarding the first straight line 54 is the arc cosine of the quotient, which is the product of this first distance 56 is formed.

Thus, it is estimated that the position is the object 8th using only the first solid angle 46 and the distance 44 located on an arc. Any deviation of the estimated position from the actual one is essentially due to the first distance 56 limited, so that the estimated position deviates from the actual only comparatively slightly and is less than 1 cm, for example.

For the exact estimation of the position 8th will continue to be a second solid angle 58 used with respect to a second straight line 60 is defined. The second straight 60 is by means of the first receiver 14 and the third recipient 18th defined that on the second straight line 60 to each other at a second distance 62 lie. The second solid angle 58 regarding the second straight line 60 is the arc cosine of the product of the signal speed 50 and the time difference 64 between the third point in time 32 and the first time 28 as well as the second distance 62 . In other words, the time difference 64 through the second distance 62 divided and the arc cosine taken away.

Consequently, after the procedure is complete 36 the position of the object 8th fully estimated and there are no more degrees of freedom. Any uncertainty regarding the actual position is essentially due to the first distance 56 and the second distance 62 certainly.

In 6 is a plan view of another embodiment of the distance sensor 6 shown in sections, which in turn the transmitter 10th as well as the three recipients 14 , 16 , 18th has on a common circuit board 66 are attached and thus lie in one plane. Here is the transmitter 10th and the first recipient 14 no longer a structural unit, but spatially separated from one another. As the first recipient 14 the one in which the time interval between the time of reception of the received signal and the time of transmission is used 26 is the least. In other words, the first recipient 14 the one the recipient 14 , 16 , 18th , in which the received signal is detected first. Thus, when method 36 is performed, it becomes the first recipient 14 always recalculated from the recipients. The second recipient 16 is the one that receives the second received signal 22 receives, that is the second smallest time interval to the transmission time 26 having.

The first straight line 54 on which the first recipient 14 as well as the second recipient 16 lie, and the second straight line 60 on which the first recipient 14 and the third recipient 18th lie, intersect at an angle of 60 °, and the first distance 56 as well as the second distance 62 are the same. Thus the three receivers form 14 , 16 , 18th the tips of an isosceles triangle, and the transmitter 10th is at the center of the triangle. This results in a symmetrical structure and the quality of the estimation is improved.

In 7 12 is a top view of an alternative embodiment of the distance sensor according to FIG 6 shown. The recipients 14 , 16 , 18th form an isosceles right triangle, being the first receiver 14 in particular forms the apex of the right angle. Thus the first and the second straight line intersect 54 , 60 always at a right angle, and here too is the first distance 54 equal the second distance 62 . The transmitter 10th is in the middle between the second and third receiver 16 , 18th . So the two solid angles 46 , 58 perpendicular to each other, which simplifies the conversion of the spherical coordinates into the Cartesian coordinates. A transformation of the angles is also not necessary.

In 8th A further embodiment of the distance sensor is shown, the arrangement of the receivers 14 , 16 , 18th is not changed. In other words, the first and second straight lines intersect 54 , 60 at an angle of 90 °, and the first and the second distance 62 , 66 are the same. Only the transmitter 10th is positioned elsewhere and points to the second transmitter 16 the second distance 62 and to the third recipient 18th the first distance 56 on. So by means of the receiver 14 , 16 , 18th and the transmitter 10th realized a square arrangement. Therefore, space is used on the circuit board 66 improved, and a shield between the transmitter 10th and the individual recipient 14 , 16 , 18th is improved.

In 9 is a further embodiment of the distance sensor 6 shown, again the arrangement of the receivers 14 , 16 , 18th is not changed. Here is the sender 10th however comparatively far from the recipients 14 , 16 , 18th arranged so that shielding is improved. The arrangement of the transmitter 10th is essentially arbitrary and takes place according to other specifications.

In summary, using the distance sensor 6 an approximation, i.e. an estimate, of the position of the object 8th performed, the distance sensor 6 is comparatively compact and does not require a control unit that requires a lot of computing and memory 34 having. Because the distance of the object 8th to the distance sensor 6 much larger than the distance between the individual components of the distance sensor 6 to each other, it is assumed in the estimation that the received signals 20 , 22 , 24th are parallel to each other, thus forming a flat waveform. Ellipticity is also neglected.

All recipients are in further embodiments 14 , 16 , 18th additionally designed as a transmitter and thus transmitter. For example, the distance sensor is used during production or at certain time intervals 6 calibrated so that a determination of the distance 44 is improved. In particular, the position of the object is estimated 8th using the analytical equations. As an alternative to this, they form a starting point in particular and an iterative calculation is carried out.

The invention is not restricted to the exemplary embodiments described above. Rather, other variants of the invention can also be derived therefrom by the person skilled in the art without departing from the subject matter of the invention. In particular, all of the individual features described in connection with the individual exemplary embodiments can also be combined with one another in other ways without departing from the subject matter of the invention.

Reference list

2nd

Motor vehicle

4th

wheel

6

Distance sensor

8th

object

10th

Channel

12th

signal

14

first recipient

16

second recipient

18th

third recipient

20

first reception signal

22

second received signal

24th

third reception signal

26

Time of transmission

28

first time

30th

second time

32

third time

34

Control unit

36

Procedure

38

first step

40

second step

42

third step

44

distance

46

first solid angle

48

Time difference

50

Signal speed

52

product

54

first straight line

56

first distance

58

second solid angle

60

second straight line

62

second distance

64

Time difference

66

Circuit board

Claims (9)

Method (36) for estimating the position of an object (8) with respect to a distance sensor (6) of a motor vehicle (2), which has a transmitter (10) and a first receiver (14) and a second receiver (16), which are integrated in a first distance (56) are arranged on a first straight line (54), at which - A signal (12) is transmitted at a transmission time (26) by means of the transmitter (10), a first reception signal (20) is received at a first point in time (28) by means of the first receiver (14), - a second received signal (22) is received at a second time (30) by means of the second receiver (16), - As the distance (44) of the object (8) to the distance sensor (6) half of the product (52) from the signal speed (50) and the time difference (48) between the first time (28) and the transmission time (26) will, and - As the first solid angle (46) with respect to the first straight line (54), the arc cosine from the quotient of the product of the signal speed (50) and the time difference (48) between the second point in time (30) and the first point in time (28) and the first distance (56) is used. Method (36) according to Claim 1 , characterized in that the first receiver (14) is the one in which the time interval between the time of reception of the received signal and the time of transmission (26) is the smallest. Method (36) according to Claim 1 or 2nd , characterized in that by means of a third receiver (18), which is arranged at a second distance (62) on a second straight line (60) from the first receiver (14), a third reception signal (24) at a third point in time (32 ) is received, and that the second solid angle (58) with respect to the second straight line (60) is the arc cosine from the quotient of the product of the signal speed (50) and the time difference (64) between the third point in time (32) and the first time (28) and the second distance (62) is used. Method (36) according to one of the Claims 1 to 3rd , characterized in that an ultrasonic wave is used as the signal (12). Distance sensor (6) of a motor vehicle (2), which has a transmitter (10) and a first receiver (14) and a second receiver (16), which are arranged at a first distance (56) on a first straight line (54), and which according to a method (36) according to one of the Claims 1 to 4th is operated. Distance sensor (6) after Claim 5 , characterized by a third receiver (18) which is arranged at a second distance (62) from the first receiver (14) on a second straight line (60). Distance sensor (6) after Claim 6 , characterized in that a right angle is formed between the first straight line (54) and the second straight line (60). Distance sensor (6) after Claim 6 or 7 , characterized in that the first distance (56) is equal to the second distance (62). Distance sensor (6) according to one of the Claims 5 to 8th , characterized in that the transmitter (10) and at least one of the receivers (10) are designed as an integrated structural unit.

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