CN112298169A - Safety system for a motor vehicle - Google Patents

Abstract

The invention relates to a safety system (1) for a motor vehicle (2), the safety system (1) comprising an on-board vehicle sensor unit (3), the on-board vehicle sensor unit (3) being configured to transmit a detection signal (D) comprising at least one detection frequency in the radar range, the on-board vehicle sensor unit (3) being configured to receive a response signal (A) returning from an object (11 to 14) and comprising at least one response frequency, the on-board vehicle sensor unit (3) being configured to correlate the at least one response frequency with the one detection frequency, thereby detecting the object (11 to 14). In order to enable a motor vehicle safety system to reliably detect obstacles, it is provided according to the invention that at least one response frequency differs from the detection frequency associated therewith by at least 5%.

Description

Safety system for a motor vehicle

Technical Field

The invention relates to a safety system for a motor vehicle having the features of the preamble of claim 1.

Background

Many modern vehicles have an Automatic Emergency Braking (AEB) system that can autonomously initiate Braking actions to avoid collisions with obstacles located in the direction of travel, such as another motor vehicle, a pedestrian, or a bicycle. Such AEB systems typically identify vehicles, bicycles, and pedestrians based on motion patterns (e.g., legs in motion) or specific contours by means of cameras and/or radar sensors. However, reliable detection is difficult because reflections, two-dimensional patterns of the surrounding environment and noise may lead to non-existent objects (ghosting) being recognized by the radar as well as the camera, resulting in false positive results. To solve this problem, very strict requirements are often required in order to identify obstacles before an automatic braking action can be performed. For example, consistent detection of two independent sensor types may be required. The basic idea here is that erroneously suppressing the execution of an emergency braking action is preferred over erroneously executing an emergency braking action.

Each new system of this type must be carefully tested for false positive results. This is expensive and time consuming as typically over 100 ten thousand kilometers of test drives are required to provide satisfactory testing.

US 6,590,236B 1 discloses a monolithic integrated circuit on which a digital circuit, an oscillator circuit and a transceiver circuit are arranged. The integrated circuit can be used in particular as part of a radar sensor of a motor vehicle in order to detect other vehicles, pedestrians or stationary objects.

US7,714,771B2 discloses a method for measuring the distance and relative speed of a plurality of objects by means of an FMCW radar, in which a detection signal containing a time-linear frequency ramp is emitted and a response signal reflected from the object is received and mixed with the detection signal. For each object, a combination of range and relative velocity values is associated with the mixer output frequency of each frequency ramp, and the range and relative velocity of a possible object is determined by the intersection of multiple range and relative velocity combinations. By randomly changing the frequency increase of at least one frequency ramp in the subsequent measurement period, apparent objects appearing due to blurring can be eliminated.

US 3,778,826 a discloses a radar system for a vehicle by which the vehicle can be braked or stopped to prevent collision with an obstacle. The system comprises transceiver means arranged on the vehicle to radiate a continuous radar signal non-modulated along the path of the vehicle and to receive reflections of objects within the path, means for detecting doppler signals based on the relative velocity between the vehicle and the obstacle, and an asymmetric T-wave coupler for distinguishing between doppler signals of receding and approaching objects, the asymmetric T-wave coupler being responsive only to doppler signals of approaching objects. In the case where an approaching object is detected, the vehicle is automatically braked or stopped.

CN 2083552U describes a collision avoidance system for a vehicle comprising a control unit, a transmitter, a receiver and an automatic braking unit. The emitter emits a modulated laser beam that is reflected by the object. The reflection from the object is registered by the receiver so that the vehicle can be braked as required. In particular, multiple transmitters and receivers may be provided to eliminate blind spots.

DE 102015207026 a1 discloses a method for controlling a detection system for detecting the surroundings of a vehicle, wherein the detection system comprises a vehicle camera for recording the surroundings and an additional environment sensor for imaging the surroundings. Distance information is thus determined which indicates whether the distance between the vehicle and the tunnel in front has fallen below a limit distance. Based on the distance information, control signals are generated to enable setting of image recording parameters of a vehicle camera for recording an interior region of the tunnel and to enable setting of imaging parameters of an additional environment sensor for imaging an exterior region of the tunnel until the vehicle enters the tunnel.

DE 102014214498 a1 describes a radar system for detecting the surroundings of a motor vehicle, which radar system comprises an oscillator for generating a high-frequency signal, transmitting means for radiating a detection signal, and receiving means for receiving a detection signal component reflected from an object, wherein the receiving means comprise at least one mixer which mixes a first signal formed by a high-frequency response signal with a second signal comprising a frequency corresponding to the oscillator signal. Thus, the negative effects of the response signal occurring due to strong reflections from the nearby vehicle-side environment of the radar system or due to reflections and/or couplings within the radar system should be avoided, since the delay means delaying the second signal for mixing such that the above-mentioned second signal has a delay with respect to the oscillator that is at least approximately equal to the response signal.

In view of the outlined prior art, there is of course still room to improve the reliability of motor vehicle safety systems based on obstacle detection.

Disclosure of Invention

The object of the invention is to achieve a reliable detection of obstacles in a safety system of a motor vehicle.

According to the invention, this object is achieved by a security system having the features of claim 1, wherein the dependent claims relate to advantageous embodiments of the invention.

It should be noted that the features and measures listed individually in the following description may be combined in any technically meaningful way and show further embodiments of the invention. The description further characterizes and specifies the invention, particularly in connection with the accompanying drawings.

By means of the invention, a safety system for a motor vehicle is provided. The motor vehicle may in particular be a passenger vehicle or a truck, and may also be a motorcycle. As will be elucidated below, in the case of some embodiments, the components of the safety system are not associated with or, rather, are not arranged on the motor vehicle itself, but interact with on-board vehicle components. However, due to this interaction they form part of a security system.

The security system comprises an onboard vehicle sensor unit configured to transmit a detection signal comprising at least one detection frequency within a radar range, the onboard vehicle sensor unit configured to receive a response signal returned from the object and comprising at least one response frequency, the onboard vehicle sensor unit configured to associate the at least one response frequency and the one detection frequency with each other to detect the object. The sensor unit may radiate a detection signal as a radar signal. The detection signal may be a continuous signal comprising exactly one detection frequency, in particular in the form of a continuous-wave (CW) radar. However, embodiments are also conceivable in which the detection signal contains a plurality of frequencies, for example a pulse signal, a square wave signal or the like. Typically, the sensor unit also contains a transmitting antenna for radar range. Furthermore, the sensor unit is configured to receive a response signal comprising at least one response frequency. The response signal is returned from the object (e.g., from a stationary or moving obstacle located in front of the vehicle). The term "return" means that the response signal is generated as a result of the detection signal reaching the object, or more precisely, in response to the detection signal reaching the object. The sensor unit is configured to correlate at least one response frequency and one detection frequency. The sensor unit detects an object, wherein a response signal comprising at least one response frequency is detected and the at least one response frequency is associated with the detection frequency, or vice versa. It is apparent that there may be several response frequencies associated with the detection frequency. In other words, the detection of the object is a function of the response signal received at the at least one response frequency. The association of the sensor unit parts means that the sensor unit classifies the response signal or, more precisely, the component of the response signal having a specific response frequency in response to a specific detection frequency related to this response frequency. This results in the detection of the object if at least one response frequency matching (i.e. associated with) the detection frequency is detected. Typically, different detection frequencies (if they occur) are associated with different response frequencies.

According to the invention, at least one response frequency differs from its associated detection frequency by at least 5%. In other words, the sensor unit is configured to receive a response signal of (at least) one response frequency, which response frequency is significantly (i.e. at least 5%) different from the detection frequency associated therewith, and to detect the object based on the received at least one response frequency. The relevant specifications relate to the detection frequency; i.e. a difference of at least 50MHz at a detection frequency of 10 GHz. The difference of at least 5% is significantly greater than the frequency difference expected due to doppler shift. That is, the sensor unit is configured to receive a returned radar signal that is not simply reflected by the object, but changes the frequency content upon returning from the object. However, a portion of the detection signal may also not change frequency after returning from the object, wherein doppler shifts may occur, which, however, may produce frequency shifts of up to several orders of magnitude in the frequency shift relative to the typical velocity of the vehicle. Therefore, the corresponding response frequency can be clearly distinguished from the detection frequency of the doppler shift. According to another embodiment, the respective response frequency may differ from its associated detection frequency by at least 10%.

Since normal objects around the vehicle, or rather the background of the objects, merely reflect radar signals, they can generate no frequency difference in the above range. Where doppler shift is most likely to occur. It is thus possible to clearly identify individual objects and to distinguish them from the surroundings, which objects do not (only) cause reflections, but (also) cause frequency shifts due to the technical characteristics of the above-mentioned objects. As described below, the respective object (e.g. a motor vehicle, a bicycle, a pedestrian or even a fixed obstacle such as a guardrail or a bollard) may be equipped with a reflector module which implements the respective frequency shift. In this way, any object can be identified in a manner that can be detected by the vehicle-mounted vehicle sensor unit. And therefore erroneous detection is almost impossible. Due to the high reliability, tedious and time consuming test drivers can be omitted. The detection by means of the sensor unit can optionally be supplemented by detection by means of other sensors (e.g. a camera).

In particular, at least one response frequency may correspond to an integer multiple of a detection frequency associated with the response frequency. In other words, the response frequency corresponds to a frequency that is a harmonic of the detection frequency associated with the response frequency. Here, "correspond" means that the respective frequencies are the same up to a doppler shift that may occur, however, at road traffic speeds, resulting in a relative difference of less than 10^-6For example, at a detection frequency of 10GHz, the relative difference is always (significantly) less than 10 kHz. If the illuminated object exhibits non-linear behavior, integer multiples of the resulting detection frequency occur,in addition to the fundamental frequency, harmonics are thereby induced, which in turn can be radiated and received by the sensor unit. The principle of operation is also known as "harmonic radar".

In particular, the response frequency may correspond to twice the detection frequency associated therewith, and/or the response frequency may correspond to three times the detection frequency associated therewith. This means that the corresponding response frequency corresponds to the first harmonic or the second harmonic. In particular, two times the detection frequency and three times the detection frequency may be detected as the response frequency. Here, a comparison of the amplitudes of the first harmonic and the second harmonic may in particular be provided. As a result, for example, an artificial semiconductor element in which the first harmonic generally has a larger amplitude can be distinguished from a rusted iron sheet in which the second harmonic generally has a larger amplitude.

In some cases it may be sufficient that the sensor unit only detects the presence of an object, for example the sensor unit only detects a small angular range (usually in the direction of travel in front of the vehicle), and the exact position may be determined by additional sensors. Preferably, however, the sensor unit is designed for detecting the direction and/or distance of an object relative to the motor vehicle. This may be possible, for example, because the sensor unit contains a phased array antenna and thus scans the area in front of the vehicle, for example, by electronically translating the radar beam back and forth. Alternatively, it is also conceivable to use two spatially spaced antennas, so that the position of the object can be determined by triangulation. In addition, the sensor unit may be designed to determine the relative speed of the object. This may be achieved, for example, by detecting the doppler shift of the response signal.

Generally, the safety system comprises an onboard vehicle control unit configured to trigger at least one safety measure of the motor vehicle upon receipt of the response signal. Here, the control unit is typically electrically connected to the sensor unit, so that the sensor unit can send a corresponding signal to the control unit upon receiving the response signal. The control unit and the sensor unit may optionally also be configured as an integrated unit. If the control unit determines the reception of the response signal, it may trigger various safety measures. The measures in question may be determined on the basis of, among other things, the position and/or relative speed of the object. For example, a seat belt tensioner may be triggered if a collision with an object is likely. Alternatively, an automatic avoidance operation may be initiated to avoid a collision. Furthermore, many other safety operations are conceivable.

In particular, the control unit may be configured to trigger braking of the motor vehicle in dependence on the reception of the response signal. Braking may slow the motor vehicle only or stop it completely. The control unit is collectively referred to as part of the AEB system. The safety system or at least its onboard components may also be collectively referred to as an Autonomous Emergency Braking (AEB) system.

Furthermore, the security system may comprise a reflector module for attachment to the object, wherein in case of receiving a detection signal comprising at least one detection frequency, the reflector module is configured to radiate a response signal comprising at least one response frequency associated with the respective detection frequency. In this case, the "reflector module" should not be construed as limiting, in particular because at least no pure reflection occurs, but a substantial change in frequency (too) occurs. It should be understood that the sensor unit and the reflector module are matched to each other to such an extent that the sensor unit is able to detect at least one response frequency radiated by the reflector module. For example, the reflector module may radiate a first harmonic and a second harmonic, wherein the sensor unit is configured to accurately detect these harmonics. Of course, multiple reflector modules may be attached to the object.

The reflector module may for example be configured for attachment to a motor vehicle, a bicycle, a person or a stationary object. As described below, the reflector module may have an extremely low weight and small size so that it can be mounted or attached in almost any position. At least in the case of attachment to a motor vehicle, a mounting is usually provided in which the reflector module can be mounted, for example, under the cladding of the bumper. In the case of a bicycle, the reflector module can be clamped, screwed or even glued on it, for example. In the case of a person, the reflector module may be sewn into the garment, or it may be integrated into a belt worn by the person on an arm or leg, for example. Of course, the animal may also be equipped with a reflector module, for example by means of a collar containing the reflector module.

It is particularly preferred that the reflector module is configured as a passive element. That is, the reflector module does not have a separate energy supply for generating or amplifying the response signal, but rather passively generates the signal only by the energy illuminated by the detection signal.

As mentioned above, the reflector module may comprise a semiconductor element. For example, the element may be a semiconductor diode. The diode may be connected to a metal antenna. According to one design, the antenna branches are interconnected by semiconductor diodes. Since the semiconductor element constitutes a nonlinear element, harmonics are generated in addition to the fundamental frequency of the detection signal, and then the harmonics form a component of the response signal. On the one hand, the semiconductor element and the antenna are inexpensive to manufacture, and on the other hand, can be designed to be very small and light. Thus, the antenna may for example be configured as a conductive layer on the film, so that the entire reflector module may even be flexible.

Drawings

Further advantageous details and effects of the invention are described in more detail below on the basis of exemplary embodiments depicted in the figures. Shown below:

FIG. 1 shows a schematic diagram of a security system according to the present invention; and

fig. 2 shows a schematic view of a reflector module for the security system in fig. 1.

Detailed Description

In the drawings, like parts have like reference numerals; therefore, they are usually described only once.

Fig. 1 shows a security system 1 according to the invention. In the above-described safety system, the sensor unit 3 and the control unit 4 connected thereto are mounted in the passenger vehicle 2. The sensor unit 3 is configured to radiate a detection signal D containing a detection frequency in a radar range. The detection frequency may be, for example, 24GHz, wherein other frequencies are of course possible, and the detection signal D may also contain a plurality of detection frequencies. If the detection signal D impinges on a regular object, such as a tree 10, this results in a reflection, wherein the reflected signal R matches the detection signal D in frequency except for a doppler shift, which may be in the range of tens or 100 hertz, for example.

However, various objects (e.g. another passenger car 11, a bicycle 12, a pedestrian 13 or a bollard 14) may be equipped with a reflector module 15 which, upon arrival of a detection signal, is configured to reflect a response signal a containing at least one response frequency corresponding to a multiple of the respective detection frequency, except for the doppler shift mentioned above. In this case, in particular, one response frequency may correspond to twice the detection frequency, and one response frequency may correspond to three times the detection frequency (the first harmonic and the second harmonic). The respective reflector module 15 may contain a semiconductor diode and an antenna connected thereto. In the case of a passenger vehicle 11, the reflector module 15 is typically mounted under an enclosure, such as a bumper. In the case of the bicycle 12, the reflector module 15 can be clamped, screwed or even glued thereto, for example. In the case of a pedestrian 13, the reflector module 15 may be sewn into the garment. In the case of a bollard 14, the reflector module 15 may be screwed or even moulded into the concrete of the bollard 14.

Fig. 2 shows a depiction of the reflector module 15 in a highly schematic form. Here, the diode 16 is connected to an antenna 17, which antenna 17 may be configured, for example, as a conductor loop on a non-conductive substrate. The antenna 17 may be depicted as an equivalent circuit diagram by a capacitor C and an inductor L, which are connected in parallel with the diode 16. The capacitor C and the inductor L constitute an oscillating circuit that can be excited by the detection signal D. Due to the non-linear behavior of the diode 16, in addition to the detection frequency of the radiation, the above harmonics are also induced and radiated as response frequencies.

In turn, the sensor unit 3 is configured to receive the response signal a of the respective response frequency and thereby detect the respective object 11 to 14. The sensor unit associates at least one response frequency (e.g. a respective first and second harmonic) with each detection frequency and detects the objects 11 to 14 depending on whether the respective one or more response frequencies are received. Due to the large frequency separation from each other from the detection frequencies, the response frequencies can also be correlated if doppler shifts occur, which are orders of magnitude smaller. In addition, the direction, distance and/or relative speed of the objects 11 to 14 may also be determined. For example, direction and distance may be determined by phased array radar or by triangulation by two spatially spaced receivers, while relative velocity may be detected by doppler shift. Alternatively, the sensor unit 3 may compare the amplitudes of the first and second harmonics, wherein the objects 11 to 14 are detected only when the amplitude of the first harmonic is larger.

As soon as the objects 11 to 14 are detected, corresponding signals are sent from the sensor unit 3 to the control unit 4. The control unit can possibly determine with the aid of additional sensor data (e.g. camera 5) whether there is a risk of collision with the respective object 1 to 14 and possibly trigger various safety measures. In particular, an autonomous emergency braking action may be triggered.

List of reference numerals:

1 safety system

2. 11 passenger vehicle

3 sensor unit

4 control unit

5 vidicon

10 trees

12 cycle

13 pedestrian

14 guard post

15 Reflector module

16 diode

17 antenna

A response signal

C capacitor

D detection signal

L-inductor

R reflected signal

Claims (10)

1. A safety system (1) for a motor vehicle (2), the safety system (1) comprising an onboard vehicle sensor unit (3), the onboard vehicle sensor unit (3) being configured to transmit a detection signal (D) comprising at least one detection frequency in the radar range, the onboard vehicle sensor unit (3) being configured to receive a response signal (A) returning from an object (11 to 14) and comprising at least one response frequency, the onboard vehicle sensor unit (3) being configured to associate at least one response frequency and one detection frequency with each other in order to detect the object (11 to 14),

it is characterized in that the preparation method is characterized in that,

at least one response frequency differs from its associated detection frequency by at least 5%.

2. The security system of claim 1, wherein the security system,

it is characterized in that the preparation method is characterized in that,

at least one response frequency corresponds to an integer multiple of a detection frequency associated with the response frequency.

3. The security system as claimed in one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the response frequency corresponds to twice the detection frequency associated therewith and/or the response frequency corresponds to three times the detection frequency associated therewith.

4. The security system as claimed in one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the sensor unit (3) is configured to detect a direction and/or a distance of the object (11 to 14) relative to the motor vehicle (2).

5. The security system as claimed in one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the safety system comprises an on-board vehicle control unit (4) configured to trigger at least one safety measure of the motor vehicle (2) upon receipt of the response signal (a).

6. The security system of claim 5, wherein the security system,

it is characterized in that the preparation method is characterized in that,

the control unit (4) is configured to trigger braking of the motor vehicle (2) as a function of the reception of the response signal (A).

7. The security system as claimed in one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

comprising a reflector module (15) for attachment to an object (11 to 14), wherein the reflector module (15) is configured to: in case a detection signal (D) comprising at least one detection frequency is received, a response signal (a) comprising at least one response frequency associated with the respective detection frequency is radiated.

8. The security system of claim 7, wherein the security system,

it is characterized in that the preparation method is characterized in that,

the reflector module (15) is configured for attachment to a motor vehicle (11), a bicycle (12), a person (13) or a stationary object (14).

9. The security system of claim 7 or 8,

it is characterized in that the preparation method is characterized in that,

the reflector module (15) is configured as a passive element.

10. The security system as claimed in one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the reflector module (15) comprises a semiconductor element (16).

Images