DE102014209746A1 - Driving assistance device for a vehicle - Google Patents

Abstract

The present invention provides a driving assistance apparatus for a vehicle 1 for transmitting and receiving ultrasonic signals and / or electromagnetic signals, comprising at least one ultrasonic sensor 2 for detecting surroundings in the near measuring range 4, which consists of a transducer element and a front body as a resonance body, and at least one further sensor 3 for detecting the surroundings outside of the near measurement area 4 adapted to transmit and receive signals based on electromagnetic waves, wherein the surroundings detection in the proximity measurement area 4 is performed by the ultrasonic sensor 2, and the environment detection outside the proximity measurement area 4 is performed by the further sensor 3 is executed. Furthermore, the present invention provides a vehicle 1 with at least one such driving assistance device.

Description

State of the art

The invention relates to a driving assistance device for a vehicle, as used inter alia in connection with motor vehicles and moving or stationary machines (for example robots, agricultural machines or construction machines), for example as a classic application as Umweisfassungshilfsmittel for a corresponding parking assistance system, among others Measurement of distances to certain objects. The driving assistance device according to the invention has for this purpose a combination of at least one ultrasonic sensor and at least one further sensor whose signal output is based on electromagnetic signal conversion. The invention also relates to a motor vehicle in which at least one such driver assistance device is installed concealed, whereby such driver assistance devices can be arranged on a bumper, a side mirror or a door section of the motor vehicle.

Recently, automobiles in this technical field often use ultrasound-based environmental sensors, which often use piezobased transducers, or electromagnetic-wave based environmental sensors, which are increasingly using radar sensors, such as long-range radar (LLR) or mid-range radar (MRR) sensors , In this case, signals are usually transmitted through a medium such as air from an emitter into a vehicle environment, reflected by an object located in the environment and detected again by the environment sensors, the transit time and / or differences in runtime and / or other variables such as amplitudes and phases of Signals are measured and evaluated.

A known problem in the use of radar sensors, for example for driver assistance when parking a vehicle, is inter alia that a Nahmesfähigkeit the known radar sensors, ie an ability of the sensors to detect the environment in a Nahmessgebereich or Nahumgebungsbereich of the vehicle, mess principle is limited to a minimum distance d _min of about 12 cm, the Nahmessbereich is usually in a distance range of 0 cm to about 80 cm to the vehicle. Furthermore, a longitudinal or longitudinal measuring accuracy σ of these sensors is generally generally limited to a very coarse resolution of approximately 3.5 cm. Outside the near measurement range, ie in a measurement range greater than 80 cm, radar sensors are increasingly used. Furthermore, such sensors may have problems in detecting low-reflectance objects, such as plastic surfaces, especially when positioned in front of highly reflective objects, such as metal surfaces. This can lead to significant losses in the longitudinal measurement accuracy, for example, up to 15 cm inaccuracy. In addition, an angle estimate of the measurement may be disturbed if there is more than one object in a section of the measuring range (so-called "Range Bin"). However, the known radar sensors have in return the advantage that with them a measurement with a long range is possible, in particular of more than 10 m.

With regard to the use of ultrasound sensors of conventional design, that is to say on the principle of a bending oscillator, also referred to as ultrasonic transducers, disadvantages are also known, such as a limitation of the maximum measuring range to about 6 m and a limitation of the close measuring capability to about 15 cm, but within This measurement range can be achieved with a high measurement accuracy in the distance measurement of <1 cm. For visual-aesthetic reasons, this type of environment sensors is preferably installed in a small size and increasingly hidden. In the case of a completely concealed installation of ultrasound sensors, however, there is, inter alia, the problem that only low measurement ranges of less than 2 to 2.5 m are achieved, inter alia, by the materials lying in front of the sensor in the concealed installation and the resulting attenuation of the measurement signal can be. In order to achieve a measuring range of more than 2 m, such sensors must be supplied with a very high transmission current. In addition, if possible, a small opening angle of the measuring signal must be provided, so a very targeted alignment of the measuring signal carried out, and the sensors are usually operated with a resonant design, ie with an operation of the piezoelectric element with the resonant frequency of the bending oscillator. Resonant operation has the advantage that the measurement signal experiences a very pronounced measurement signal amplitude. However, a disadvantage of the resonant operation is that the flexural vibrator generally has a weak internal damping and thus resonates over a longer period in which no signal can be detected by the sensor. In the event that a Nahmessbereich is to be detected, in which the emitted measurement signal is thrown back almost immediately and must be detected, therefore, such a ringing of the sensor, during which the sensor is not receptive, unfavorable. Furthermore, a large number of sensors compared to currently known Umweisfassungssystemen necessary to the so-called field of view ("field of view "or abbreviated" FOV "), for example, the environment of the entire bumper of the vehicle to cover. The concealed shoring also leads to a deterioration of Nahmaßfähigkeit to a range of> 20 cm. In addition, such sensors have a very high temperature sensitivity of Messsensitivität, which is equivalent to a non-achievement of the coverage requirement over the entire temperature range. In contrast, the unobstructed installation of ultrasonic sensors following the principle of a thickness vibrator sometimes requires a large installation depth, as a substantial length of the sensors is required to achieve a high amplification effect for high measurement ranges.

A known system in which already ultrasonic sensors and radar sensors can be used in parallel in a vehicle as a driving assistance system, among other things, the published patent application DE 10 2008 047 284 A1 in which a driver assistance system for assisting a driver of a vehicle when parking out of a parking space is described, which has both a radar-based and an ultrasound-based measuring system. The data of the ultrasonic sensors in the near measurement range are fused with those of the radar sensors in the far range. The system described therein, inter alia, a known ultrasonic sensor is used, as he inter alia in 2 shown as state of the art and among other things, for example, from the DE 602 14 948 T2 is known. In order to achieve sufficient transmission strengths and high reception sensitivities, these sound transducers are predominantly resonant oscillators, which consist of solids and one or more piezo elements. The well-known ultrasonic sensor 9 who is behind a vehicle outer wall here 8th , as shown for example a shock absorber outer wall, hidden installed, consists of a housing 91 a piezoelectric transducer element 92 including metallization layers, as well as a front body 93 , also called frontend, and a hind body 94 , also called backend, and forms a known λ / 2 oscillator (in words: "lambda-half oscillator"). The vibrator is over a holding device 95 with the housing 91 connected. As a λ / 2 oscillator that design of an ultrasonic sensor is referred to, in which the sum of the lengths of the back body, piezo transducer and front body is exactly half the wavelength of the ultrasound to be emitted in the material. This can be a gain effect, that is, a so-called resonant design with respect to the sensitivity and the emitted ultrasound reach. In order to achieve a high range with simultaneously low power consumption, this is usually the favored type of construction of an ultrasonic sensor for an environment detection system of a vehicle. For front body and back body materials are usually used with the lowest possible attenuation. The disadvantage here is that the total length of the vibrator is very large, typically greater than 2 to 4 cm, whereby the installation of such an ultrasonic sensor in a bumper of a vehicle due to pedestrian protection guidelines difficult to impossible.

Thus, there is a need to provide close proximity sensing capability of vehicles with concealed systems, down to about 0 cm, for example, for start-up enableings in automatic parking or in automatic driving. At the same time, a braking intervention during automatic driving also requires a high measuring range of the surroundings detection sensor system, even at higher speeds. Known systems, which are constructed only from sensors of a single specific type of sensor with concealed mounting method, can not meet these requirements.

Disclosure of the invention

In order to solve the above-described problems of known driver assistance systems, the present invention provides a driving assistance apparatus for a vehicle for transmitting and receiving ultrasonic signals and / or electromagnetic signals comprising at least one ultrasonic sensor for detecting surroundings in the near measuring range, consisting of a transducer element and a front body As a resonant body, and further comprises at least one further sensor for detecting surroundings outside the Nahmessbereichs adapted to transmit and receive signals based on electromagnetic waves. The surrounding detection in the near measuring range is performed by the ultrasonic sensor and the surroundings detection outside the near measuring range is carried out by the further sensor in order to combine the advantages of different techniques. With the driving assistance device according to the invention, a combination of a concealed built-ultrasonic sensor is thus achieved with an alternative, also concealed to be installed sensors with limited Nahmessfähigkeit, such as radar or the like. The "combined" system is to be understood to mean that the Nahmesfähigkeit the driving assistance device according to the invention 0 to α cm exclusively by a suitable ultrasonic sensor element and a measuring capability outside the Nahmessbereichs, ie above α cm is made exclusively by the other sensor such as the radar sensor. The value α is typically <20 to 50 cm. More specifically, the close range of the driving assistance device according to the invention, so the measuring range in the vicinity of the vehicle, preferably at a distance of 0 cm to 80 cm from the vehicle, preferably at 0 cm to 50 cm, more preferably at 10 to 30 cm.

According to an advantageous embodiment of the driving assistance device according to the invention, the ultrasonic sensor and / or the further sensor are concealed. Further preferably, the concealed built-ultrasonic sensor is adapted to achieve a measuring range with wide or large horizontal opening angle, preferably +/- 60 °, more than 30 cm range more preferably + / 90 °, and provided as an alternative sensor further sensor is adapted to to achieve a horizontal measuring range with reduced or small opening angle, preferably +/- 30 ° -45 °. One advantage of a larger opening angle of the ultrasonic sensor in the near measurement range is, inter alia, that fewer sensors must be arranged on the vehicle, for example in the bumper, in order to cover the entire field of view (overall FOV), whereby the total number of sensors in the overall system can be kept low. A susceptibility to errors can be kept correspondingly low and costs can be saved. An advantage of a smaller opening angle in the far range in the case of the further sensor lies, for example, in the possibility of focusing the sensor and in the simultaneously higher range, or else in the same range in a lower necessary transmission power. Furthermore, a higher measurement robustness is achieved because fewer objects are detected in the field of view of the sensor. This is derived from the fact that several objects at the same distance can lead to large lateral and longitudinal errors of the measurement and correspondingly to uncertainties or ambiguities in the measurement of the overall system.

According to a preferred embodiment of the driving assistance device according to the invention, the ultrasonic sensor is formed without a back body, which is only possible by dividing the measurements in the near measurement range and outside of the close measurement range using various sensor techniques. This means that by relieving the ultrasound sensor outside of the near measuring range, this requires a lower transmission power, for example 1-2 W, and thus to the complex structure of the sensor, as shown in FIG 2 As shown in the prior art known, can be dispensed with a rear body as part of the resonator. Consequently, the thus shortened ultrasonic sensor requires a small installation depth in the vehicle, for example in the bumper of the vehicle. A sensor with a back body can be assumed to have a length of 26-30 mm. A sensor without back body, however, may have a length of 10-15 mm. This can lead to improved conditions for pedestrian protection in addition to the obvious cost savings, as well as a significantly improved perception or non-perception of the sensors can be achieved on the vehicle. Further preferably, the front body of the ultrasound sensor can also be adapted accordingly to the lower requirement, for example by a corresponding design of the ultrasound sensor or especially of the front body for a broadband signal generation with high attenuation, ie in a shortened form of the front body in comparison to a known ultrasonic sensor , A resonant operation of the sensor with the back body is 2-5 kHz, while operation outside the resonance range can be> 10 kHz without a back body. Preferably, the ultrasonic sensor experiences excitation with pulses in the frequency range> 50 kHz outside the resonance range, wherein operation outside of the resonance makes it possible to emit measurement pulses over a wide waveband range in comparison to the narrow resonance range. Due to the non-resonant operation of the sensor, which corresponds to the broadband operation in a wider wavelength range with lower, quickly decaying pulse levels, a greatly improved Nahmesfähigkeit the concealed sensors can be achieved <20 cm, in particular by the combination of the sensor excitation with very broadband pulses in the frequency range> 50 kHz out of resonance, whereby a higher attenuation of the sensor can be achieved.

According to a preferred embodiment of the driving assistance device according to the invention, the transducer element of the ultrasonic sensor has a piezoelectric element with a small diameter of preferably between 10-12 mm, more preferably with <6 mm, whereby additional space can be saved in the vehicle. The thickness of the piezoelectric element, also referred to as a piezoelectric disk, can be further reduced to <1 mm, whereby further space and beyond material and thus costs can be saved. Incidentally, the present invention provides a vehicle having at least one driving assistance device as described above. The driver assistance device is provided on the vehicle such that the at least one ultrasound sensor or a plurality of these are preferably concealed in the bumpers of the vehicle, wherein the at least one further sensor is either also concealed in the bumpers, or else elsewhere can be installed on the vehicle. In general, the installation location of the sensors of the driving assistance device according to the invention is not limited to the bumper of the vehicle, but may be provided elsewhere, for example in side rails of the vehicle, in the side mirrors of the vehicle, in the roof structure of the body of the vehicle or the like.

Advantages of the invention

By the driving assistance device according to the invention, the inherent temperature dependence of concealed built-ultrasonic sensors can be compensated by the achieved reduction in range requirements, for example, to <50 cm, and thereby a measurement accuracy of the overall system can be significantly improved. The concealed built ultrasonic sensors according to the invention can be designed by the discharge in the remote measuring range based on the other sensors also with high performance in Nahmessbereich, for example by a broadband design of the sensor, that is, the excitation of the sensor outside the resonance. The sensor signals obtained thereby can be made in a wide wavelength range, in which wavelength range many measuring pulses can be placed, for example, to operate different sensors "parallel" to each other with different pulse wavelengths, whereby the various pulses have a high separation ability from each other. As a result, the requirements for the respective sub-component are defused, whereby a cost-effective and in the case of a concealed sensor installed technically possible realization in the overall system is achieved. In the case of the concealed ultrasonic sensor, this means, for example, that the sound pressure and thus the transmission current can be significantly reduced and existing known application-specific integrated circuits, so-called ASICs can be used to control the sensors, which in turn leads to a significant cost savings.

Brief description of the drawings

1 shows a vehicle with a driving assistance device according to the preferred embodiment of the invention; and

2 shows an ultrasonic sensor according to the prior art. Preferred embodiment of the invention

In 1 is a front part of a vehicle 1 , also called motor vehicle, shown, which is provided with a driving assistance device according to a preferred embodiment of the invention. The driving assistance device according to the invention consists in the preferred embodiment of at least one ultrasonic sensor 2 in a bumper 11 of the vehicle 1 concealed is installed, and from at least one other sensor 3 For example, a radar sensor hidden in an A-pillar 12 of the vehicle 1 under the roof construction 13 of the vehicle 1 is installed. The ultrasonic sensor 2 of the driver assistance system according to the invention sends a measurement signal for detecting the environment of the vehicle 1 in front of the bumper 11 of the vehicle 1 specifically for a close range measurement 4 is designed, which is preferably 0 to 30 cm in length. The ultrasonic sensor learns about this 2 a broadband or non-resonant excitation with pulses in the frequency range> 50 kHz with high internal damping, resulting in a greatly improved Nahmessfähigkeit the concealed built-ultrasonic sensor 2 in the close range 4 is reached. The concealed built-in ultrasonic sensor 2 , which must act by the inventive combination of ultrasound technology and radar technology in the driving assistance device according to the invention only in the Nahmessbereich has a similar structure as in 2 illustrated ultrasonic sensor 9 , however, being on the back body 94 can be waived. Due to the correspondingly reduced range requirements for the ultrasonic sensor 2 in the proposed overall system, the design of the known ultrasonic sensor 9 be changed so that its depth and Nahmähfähigkeit is optimized. The reduced overall depth achieved in this way leads to improved conditions for pedestrian protection with regard to the construction of the bumper, as well as to allow a hidden Verbaus the ultrasonic sensor 2 in the bumper 11 of the vehicle, by which an optical aesthetics of the vehicle is substantially improved. Furthermore, the front body 93 of the ultrasonic sensor 2 Also called ultrasonic transducers, are designed in a broadband wavelength range outside the resonance with compared to the resonance mode higher internal damping, which optionally can also be shortened to save further space. Such a broadband design of the front body 93 of the ultrasonic sensor 2 has a higher robustness to frequency shifts and a better Nahmaßfähigkeit result. In addition, in the ultrasonic sensor 2 by reducing the reach requirement, the diameter of the piezo element 92 be reduced, which leads to further cost savings.

At the in 1 The preferred embodiment shown are each an ultrasonic sensor 2 and an additional sensor acting as a radar sensor 3 shown and described. However, it is considered understood that a variety of ultrasonic sensors 2 and a variety of other sensors 3 on the vehicle 1 can be provided to the entire environment of the vehicle 1 cover as completely as possible. Furthermore, at the in 1 shown embodiment of the ultrasonic sensor 2 on the bumper 11 and the other sensor 3 in or at the A-pillar 12 of the vehicle 1 concealed installed. The ultrasonic sensor 2 as well as the sensor 3 However, you can also side by side in the bumper 11 be installed concealed, or may be at another appropriate location on the vehicle 1 be hidden installed, as long as an environment detection obstacle-free is possible. It would be conceivable, for example, the sensors 2 . 3 the driver assistance device according to the invention in sidebars (not shown) of the vehicle 1 to integrate or other components of the vehicle 1 such as the side mirrors or the grille as a mounting location for such sensors 2 . 3 to use.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008047284 A1 [0005]
• DE 60214948 T2 [0005]

Claims (11)

Driving assistance device for a vehicle ( 1 ) for transmitting and receiving ultrasonic signals and / or electromagnetic signals, with at least one ultrasonic sensor ( 2 ) for environment detection in the near measurement range ( 4 ), which consists of a transducer element and a front body as a resonance body, and at least one further sensor ( 3 ) for environment detection outside of the near measuring range ( 4 ) adapted to transmit and receive signals based on electromagnetic waves, wherein the surround detection in the near measurement range ( 4 ) by the ultrasonic sensor ( 2 ) is carried out, and wherein the surroundings detection outside the Nahmessbereichs ( 4 ) through the further sensor ( 3 ) is performed. Driving assistance device according to claim 1, wherein the ultrasonic sensor ( 2 ) no backbody ( 94 ) having. Driving assistance device according to one of the preceding claims, wherein the front body of the ultrasonic sensor ( 2 ) is designed for broadband signal generation with high attenuation and provided in a shortened form. Driving assistance device according to one of the preceding claims, wherein the transducer element of the ultrasonic sensor ( 2 ) is a piezoelectric element with a small diameter, preferably between 10-12 mm, more preferably with <6 mm. Driving assistance device according to one of the preceding claims, wherein the ultrasonic sensor ( 2 ) and / or the further sensor ( 3 ) obscured on the vehicle ( 1 ) is installed. Driving assistance device according to one of the preceding claims, wherein the ultrasonic sensor ( 2 ) experiences a broadband excitation with pulses in the frequency range> 50 kHz outside its resonant frequency. Driving assistance device according to claim 6, wherein the ultrasonic sensor ( 2 ) has a measuring range with an opening angle of at least +/- 60 °, wherein the opening angle at a measuring distance of less than 30 cm is preferably at least +/- 90 °. Driving assistance device according to one of the preceding claims, wherein the further sensor ( 3 ) is a radar sensor. Driving assistance device according to claim 8, wherein the further sensor ( 3 ) a measuring range with an opening angle of +/- 30 ° to 45 °. having Driving assistance device according to one of the preceding claims, wherein the proximity measuring range ( 4 ) Is 0 cm to 50 cm to the vehicle, preferably 0 cm to 50 cm, more preferably 10 to 30 cm. Vehicle ( 1 ) with at least one driving assistance device according to one of the preceding claims.

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