DE102006008476A1 - Run time signals producing method for determining distance of e.g. bollard, involves receiving ultrasonic waves from object by ultrasonic transducers under formation of received signals, and evaluating received signals - Google Patents

Abstract

A Apparatus for generating a runtime signal for a determination a distance of an object (2) by measuring the duration of Ultrasonic pulses comprise at least two in a given one Distance from each other arranged ultrasonic sources (12, 13) with smooth emission area, the transmission signals in by the transmission signals convert certain ultrasonic waves and radiate the ultrasonic waves, so that they interfere interfering, and a control and evaluation device (9), which is designed to transmit signals for the at least two ultrasonic sources (12, 13) to form and deliver so that these simultaneously ultrasonic waves with the same frequency and predetermined phase relationship, and at least one receive signal, the at least one ultrasonic transducer (12, 13), the at least has one of the at least two ultrasonic sources, and / or a further ultrasonic transducer (12, 13) received by conversion, reflected from the object (2) Ultrasonic waves is formed to receive and form the Evaluate the runtime signal.

Description

The The present invention relates to a method and an apparatus for generating a runtime signal for a determination of a distance of an object by measuring the transit time of ultrasonic pulses

Motor vehicles In particular passenger cars, are often designed so that they one possible have lower drag coefficient. This has the advantage that on the one hand a low fuel consumption and on the other a higher one Final speed can be achieved. Often, such motor vehicles However, this one, for example, a wedge-like shape, the Visibility limits when parking. This will make parking for makes a driver difficult.

to Relief of the parking process therefore distance warning systems are often used, the use a runtime method for distance determination. These include on the one hand in the bumpers of Vehicles arranged ultrasonic sensors and with these via signal connections connected control unit, that's too big for the driver approach warns of an obstacle. The ultrasonic sensors comprise a Ultrasonic transducer, the electrical transmission signals in ultrasonic waves converts and / or impinging ultrasonic waves into received signals converts and a circuit for emitting the transmission signals and / or the evaluation of the received signals. As ultrasonic transducers hereinafter referred to as any means that electrical Receive signals and through the electrical signals certain ultrasonic waves radiate and / or receive ultrasonic waves and characteristics the ultrasonic waves, in particular their amplitude and / or frequency and / or phase, reproducing, receive electrical signals and can leave. Ultrasonic transducers used in motor vehicles can often both as a sender as well as a receiver be used.

The System of ultrasonic sensors and control unit operates according to the transit time method.

Under A runtime method is doing, regardless of the previously described Devices, hereinafter understood that a transmission signal for Delivered an ultrasonic pulse and corresponding ultrasound pulses be emitted and that of an object optionally thrown back Receive portions of the emitted ultrasonic pulse and corresponding Receiving signals are formed. The received signals are under Forming a runtime signal evaluated, the runtime signal the duration of the ultrasonic pulse from the transmitter to the object back to the recipient reproduces. This can be analog or by the shape or size of the signal done digitally. However, the runtime signal can also runtime simply by reproducing it in one of the duration of the ultrasonic pulse corresponding time interval from the delivery of the transmission signal or one of the output of the transmission signal triggering signal is formed and is delivered. From the runtime signal can then run time and from this together with the well-known ultrasonic speed in air and the relative position of the ultrasonic pulse emitting and the one who is thrown back Share receiving facilities the distance of the object determined become.

at the mentioned known distance warning systems, the control unit controls the ultrasonic sensors to deliver the transmission signals and thus the ultrasonic pulses. To Delivering a pulse, the ultrasonic transducers are operated as a receiver and optionally receive portions of the emitted ultrasound pulses that are reflected by the object and form from these received signals, which are evaluated to form the runtime signals become. The runtime signals are then processed and, in particular Determining a distance delivered to the controller.

Around to help a driver to find a parking space and to park, It is proposed to at least semi-automatic parking enable, in which a corresponding control park the motor vehicle in a parking space. This can at a known relative position of motor vehicle and parking space and known dimensions of the parking space Park the vehicle very space-saving, so that's why also close parking spaces without substantial effort can be used by the driver.

to Determining the dimensions of the parking space may be a distance detection system used that similar works like the distance warning system described above. there However, then ultrasonic waves are transverse to the direction of travel of the motor vehicle emitted while this passes a parking space. there are successive distance values in the direction transverse to the direction of travel captured, from which both the length as well as the depth of the parking space can be determined. However, for this it is necessary that the Range of the system, i. the maximum distance in which still safe an object can be detected, sufficiently large, typically at least 4 m, is.

For design reasons, however, the ultrasonic transducers should have a rather smooth surface over which the ultrasonic waves are emitted. This can lead to the required range not being reached with reasonable effort can be.

Of the The present invention is therefore based on the object, a method Generating a runtime signal for a determination of a distance of a Object by measuring the transit time of ultrasound pulses, which allows a simple distance determination and has a long range, as well as means of implementation of the method.

The Task is solved by a method for generating a runtime signal for a determination a distance of an object by measuring the transit time of ultrasonic pulses, in the case of at least two at a predetermined distance from each other acoustically separated locations simultaneously ultrasonic waves with the same frequency with a given phase relationship are radiated to each other, so that they overlap interfering and at least one ultrasonic pulse, and / or in the form of ultrasonic waves emitted to the object simultaneously at two in one predetermined distance from each other acoustically separated places below Formation of received signals are received and the received signals in dependence be evaluated from each other to form the runtime signal.

The Task will be solved further by a first device for generating a runtime signal for one Determining a distance of an object by measuring the transit time ultrasonic pulses, comprising: at least two in a predetermined one Spaced ultrasound sources with a smooth radiating area, convert the transmission signals into ultrasonic waves and the ultrasonic waves so that they overlap each other in an interfering manner, and a control and evaluation, which is adapted to transmit signals for the at least two ultrasonic sources to form and deliver, so that These simultaneously ultrasonic waves with the same frequency and predetermined Phase relationship, and at least one received signal, the at least one of the ultrasonic transducers, the at least one of has at least two ultrasonic sources, and / or a further ultrasonic transducer formed by converting received, reflected from the object ultrasonic waves is to receive and evaluate to form the runtime signal.

The Task is about it also solved by a second device for generating a runtime signal for a determination a distance of an object by measuring the transit time of ultrasonic pulses, comprising: at least two at a predetermined distance from each other arranged ultrasonic transducers with a smooth receiving area, which are adapted to receive ultrasonic waves, in received signals to convert and to give the received signals, and a control and Evaluation device, which is designed to transmit signals for at least an ultrasonic source comprising at least one of the ultrasonic transducers and / or another ultrasonic transducer comprises, so that the at least one ultrasound source determined by the transmission signals Ultrasonic waves radiate, and received signals of at least two ultrasonic transducers, received by conversion, from the Object thrown back Ultrasonic waves are formed, received and together under education evaluate the runtime signal.

The This invention is for use with a transit time method for determination the distance of the object is provided. As a distance, in particular the mean distance of the object from the two locations or the ultrasound sources or the ultrasonic transducers are used.

Under A runtime method or pulse transit time method is thereby a Method used, which has the features described above. at Such a method, as already mentioned, pulses of ultrasonic waves submit. The ultrasonic waves have at least one predetermined Frequency, in principle be chosen arbitrarily can. Preferably, however, the frequency and the used Ultrasonic transducer matched, so that the ultrasonic transducer with as possible greater Efficiency Send ultrasonic waves of the given frequency or can receive and convert into received signals. These ultrasonic waves are delivered in the form of pulses whose duration as in known Distance detection systems selected can be.

According to the invention according to a first variant of two from each other with a given Spaced apart locations emitted ultrasonic waves, what the ultrasound sources are for the first device. there it is essential that the places are acoustically separated from each other, in the context of the present invention is understood that between these places material is present, the ultrasound of the radiated frequency in an area between the two places at least strongly attenuates.

To deliver the ultrasonic waves, in the first variant, according to a preferred embodiment, two separate and therefore acoustically separate ultrasonic transducers can be used as ultrasound sources. In another preferred embodiment, however, it is also possible to use only one ultrasonic transducer, in front of the one in the emission direction with at least two acoustically separated, arranged in the predetermined distance openings is ordered, one of which represents an ultrasonic source in conjunction with the ultrasonic transducer.

One Element of the present invention is to increase the range of at least two locations of ultrasonic waves of the same frequency and transmit with a predetermined phase relationship that in the overlay area interfere. To do this the ultrasonic waves radiated in a suitable direction from the places in particular, have to The ultrasound sources should be aligned so that an overlay and thus allows interference becomes. This can not only be a higher intensity in one by phase relation given direction, but also one more Anisotropy of the radiation characteristic, in particular a lobe characteristic in at least one level. In the first device is to the control and evaluation designed to both To control ultrasonic sources in a corresponding manner. It needs the Control and evaluation device for example, only in a suitable electronic circuit to pass. The tax and Evaluation device can in particular still by a control unit by control signals be controlled to transmit ultrasonic pulses through the control signals at certain times.

The optionally reflected by the object ultrasonic waves or pulses can then for example, as in known devices received and in Runtime signals are implemented. These runtime signals can be, for example in the control unit be used to determine the distance.

at the second variant or the second device is exploited, that the receiving characteristic and sensitivity of an arrangement of ultrasonic transducers of the radiation characteristic of a through the Ultrasonic transducer formed arrangement of ultrasonic sources corresponds. To do this the received signals of the ultrasonic transducer together under consideration the phase relationship of the received signals are evaluated. The Control and evaluation is therefore in the second device for the common evaluation of the received signals of the ultrasonic transducers formed, preferably the phase relationship of the received Supervised ultrasonic waves and thus the received signals to each other. Thus, analogously to the first variant, a more direct reception characteristic results and greater sensitivity in at least one direction than when using only one ultrasonic transducer. This results in an increased Range of the entire device.

at The device, and preferably the method, are ultrasound sources or ultrasonic transducers used which a smooth emission or Receiving area have. By this is meant that the radiating or by the ultrasonic waves to be received element of the ultrasound sources or transducer, for example a membrane, not in an ultrasonic beam Structure, for example, in a tube, sunk in the direction of radiation greater than about half the wavelength is. Thereby can Pollution problems are avoided. At the same time, it is an integration in a largely arbitrary design of a body or a Bumper one Motor vehicle possible.

Basically need the ultrasonic sources do not serve as ultrasonic receivers. Preferably However, at least one ultrasonic transducer of the first or second Device both as an ultrasonic source and for the reception of Ultrasonic waves, i. used as an ultrasonic receiver. Especially Thus, in an apparatus according to the first variant, an ultrasonic transducer one of the ultrasonic sources serve as an ultrasonic receiver. Conversely, can in a device according to the second variant of the ultrasonic transducer serve as an ultrasound source. However, it is preferred in the method that for the radiation of the ultrasonic waves and for the reception of the ultrasonic waves the same ultrasonic transducers are used. In the first variant For this purpose, the device preferably has at least two ultrasound sources in each case at least one ultrasonic transducer, which is also designed as an ultrasonic receiver is that converts received ultrasonic waves into received signals and this gives off, and the control and evaluation is on configured to receive the received signals of the at least two Ultrasonic transducer receives and in the evaluation together, preferably in compliance with Phase relationships of the received signals used. At the second Variant of the device are the at least two ultrasonic transducers Also designed as ultrasonic sources that are in response to transmission signals emit certain ultrasonic waves through the transmission signals, and in which the control and evaluation further trained is the transmission signals for to form and deliver the at least two ultrasonic transducers so that these simultaneously with the predetermined ultrasonic waves Give frequency and given phase relationship.

In particular, therefore, the emission area can simultaneously serve as a reception area. This has the advantage that by using the two ultrasound sources a particularly high range and at the same time by using the two ultrasonic sources or of ultrasonic transducers of these sources a very good directional characteristics at clotting can be achieved according to equipment expenditure.

The Locations or ultrasound sources and / or transducers can in principle be spaced as desired. In the method, however, is preferably the distance of at least two places less than 20, preferably 10 wavelengths, especially preferably 5 wavelengths, the ultrasonic waves of the given frequency in air. Both Devices is preferably the distance of at least two Ultrasonic sources or ultrasonic transducer smaller than 20, preferably 10 wavelengths, particularly preferably 5 wavelengths, the ultrasonic waves in air. Below the wavelength of ultrasonic waves in Air becomes the wavelength in air at an air temperature of 20 ° C, in particular at normal pressure, understood. This embodiment has the advantage that further maxima resulting from interference intensity so far away from the main maximum that these are the detection do not significantly affect.

For the invention it is important that the given distance of the places or Ultrasonic sources and / or converter is respected, otherwise the effect of the interference of the transmitted ultrasonic waves or the phase angle of the ultrasonic waves to be received at the receiving locations or Ultrasonic transducers is not achieved to the desired extent. It is therefore preferred in the first and second apparatus that the at least two ultrasonic sources or ultrasonic transducer together are held in a single holding device. This has the Advantage that the relative position of the therein by the holding device held ultrasound sources or transducers and in particular their Distance from each other can be kept very simple and accurate. In particular, it is possible a module with the holding device and the ultrasonic sources held therein or converters to manufacture that without further adjustment in a motor vehicle or a bumper installed can be. The holding device may be, for example a plastic injection molding act in the receptacles for conventional Ultrasonic transducers are formed.

For as possible Precise determination of the dimensions of a parking space is necessary that the maximum intensity the transmission intensity distribution or emission characteristic or the maximum sensitivity of the Sensitivity distribution or reception characteristic as possible exactly orthogonal to the direction of travel of the motor vehicle or the longitudinal axis of the motor vehicle is aligned. A mechanical alignment However, the ultrasound sources or transducer is expensive, especially there on the one hand, the emission or receiving surfaces as plan as possible with the adjacent body surface attached and to achieve the desired transmission or reception characteristic must be arranged to each other. It is therefore preferred in the method that a predetermined Phase shift between the emitted ultrasonic waves generated is or receiving phases of the received ultrasonic waves by one predetermined phase shift are shifted from each other. at In the first device, it is preferable that a device for shifting the transmission phases of the ultrasonic waves to be transmitted to one another is provided, by means of which a predetermined phase shift is generated between the transmitted ultrasonic waves. In the second device, it is preferable that a device for shifting the reception phases of the received ultrasonic waves is provided by a predetermined phase shift to each other. This has the advantage that by selecting the phase shift, the the phase relationship between the transmitted ultrasonic waves or determined the received signals, possible is the direction of the Sendeintensitätsmaxi mums or the direction of maximum reception intensity to change. So it's sort of an electronic pivoting of said maxima possible, without that a mechanical adjustment would be necessary. As institutions can do this in particular electrical switching elements or circuits used be adjusted by means of which the phase shift.

This embodiment also has the advantage that not only a simple alignment of the emission or reception characteristic is possible, but the ultrasonic sources or transducers can be arranged on a surface of the motor vehicle, which is not parallel to the vehicle longitudinal axis. For example, an installation in slightly curved areas of a bumper is possible, which offers as an advantage much greater design freedom for the bumper or other parts of the body in which the device is to be arranged. In particular, it is preferable in the method that the value for the phase shift is selected such that the maximum of the radiated intensity of the superimposed ultrasonic waves lies in a direction that is inclined with respect to a connecting line of the at least two locations or that the value for the Phase shift is selected so that the maximum of the reception sensitivity for a reception at the two locations and the common evaluation is in a direction which is inclined relative to a connecting line of the at least two locations. In the case of the first device, it is preferable for the value for the phase shift to be selected such that the maximum of the radiated intensity of the superposed ultrasonic waves of the at least two ultrasound sources lies in a direction opposite to a connecting line of the at least two ultrasound sources is inclined. In the case of the second device, the value for the phase shift is preferably chosen such that the maximum of the receiving sensitivity of the device lies in a direction which is inclined with respect to a connecting line of the at least two ultrasonic transducers.

The Phase shifts for Transmitting and receiving are preferably the same if the at least two ultrasonic transducers operated as both transmitter and receiver become.

Basically the phase shift, for example, when planned installation in a relation to the longitudinal axis inclined surface, fixed according to the expected inclination. It is however, in the method, it is preferable that a value for the phase shift is detected or determined and used. At the first and / or second device, it is preferable that the control and Evaluation device is further adapted to a value for the phase shift to capture or determine and to use the determined value. This allows a simple alignment of the transmission or reception characteristic the device even after installation in a motor vehicle. Especially is also a simple readjustment possible. The control and evaluation device may have an input or an interface for capturing Have data representing the phase shift or a change reflect the phase shift. However, it is also possible that this automatically determines the phase shift by, for example Scanned a predetermined range of phase shifts, wherein each detects received signals, and in response to a detected Maximum of the received signals depending on the set Phase shifts determines the phase shift to be used.

Around also more detailed information about Objects in the near field, i. at a distance of less than 200 wavelengths Ultrasonic waves from the locations or the ultrasonic sources or Converters, it is preferred in the process that Measurement of the distance in the near field of one of the locations ultrasonic waves for one Pulse transit time sent out and at another the place of thrown back to the object Shares of the ultrasonic waves are received. At the first and / or second Device, it is preferred that the control and evaluation is further designed so that for measuring the distance in the near field a the ultrasonic sources or one of the ultrasonic transducers as an ultrasonic transmitter and another of the ultrasonic sources or another of the ultrasonic transducers as an ultrasonic receiver for one Pulse transit time measurement is operated. This embodiment has the advantage that at the same time one of the ultrasound sources as an ultrasonic transmitter and one of the ultrasonic transducers that is not part of the ultrasound source is, as a receiver can be used. This is for the ultrasound source does not switch from transmit mode to receive mode necessary, so also distances can be detected at very close range. This offers the advantage Use the device as a distance sensor for short distances to be able to.

Just in the near field, the position of the object relative to the device, i.e. not only the distance, but also the direction relative to vehicle longitudinal axis or radiation direction or another reference axis, of considerable Interest, for example when parking. In the process is therefore preferred that for measuring the position of the object in the near field successively each of one of the two locations ultrasonic waves for one Pulse transit time sent out and reflected by the object Receive portions of the ultrasonic waves and corresponding pulse transit times be determined, and from the pulse transit times by means of triangulation data are determined, which reflect the position of the object. In the The first device is to the control and evaluation preferably further configured so that for measuring the position of the object in the near field one after the other, one of the ultrasonic sources as Ultrasonic transmitter for a pulse transit time measurement is operated, and from the maturities By means of triangulation data are determined which the location of the object play. As a variant, it is preferable in the method that for measuring the position of the object in the near field one after the other respectively ultrasonic waves of a pulse transit time measurement at one of the at least two locations received and corresponding pulse transit times are determined, and be determined from the transit times by means of triangulation data, which reflect the position of the object. In the second device For this purpose, the control and evaluation device is preferably further is designed so that for measuring the position of the object in the near field successively each one of the ultrasonic transducers as ultrasonic receiver for a pulse transit time measurement is operated, and from the maturities using triangulation data are determined, which reflect the position of the object. These trainings have the advantage that the devices are not limited to the distance, but can also be used for orientation.

The Invention is preferably used in parking systems for motor vehicles.

The Invention will be further exemplified below with reference to the drawings explained. Show it:

1 a schematic representation of a motor vehicle with a known distance center system when driving past a parking space,

2 a schematic representation of a motor vehicle with a distance detection system having a device for generating a runtime signal according to a first preferred embodiment of the invention, when driving past a parking space,

3 a schematic representation of a module of the device in 2 with two ultrasonic transducers held in a holding device,

4 a schematic partial representation of a motor vehicle with a arranged in the bumper area distance detection system having a device for generating a propagation time signal according to a second preferred embodiment of the invention, and

5 a schematic representation of a module with two ultrasonic sources for a device for generating a propagation time signal according to another preferred embodiment of the invention.

In 1 has a motor vehicle 1 that is connected to objects 2 , for example, bollards, limited parking space 3 passes by, via a known distance detection system 4 , which has a transverse to the vehicle's longitudinal axis 5 and thus the direction of travel arranged ultrasonic transducer 6 , with a known control and evaluation 7 connected via signal connections, and a control unit 8th for controlling the control and evaluation device 7 features.

The ultrasonic transducer 6 , which serves as both an ultrasonic source and as an ultrasonic receiver, has an in 1 indicated by a dashed circle transmission and reception characteristics in a plane parallel to the road through the ultrasonic transducer 6 has a substantially circular cross-section. The maximum of the characteristics is ideally orthogonal to the vehicle's longitudinal axis 5 aligned.

The trained as an electronic circuit control and evaluation 7 serves to a start signal of the control unit transmission signals for the ultrasonic transducer 6 form and deliver to this, so that it radiates to the transmission signals to the transmission signals corresponding pulse of ultrasonic waves corresponding to the natural frequency of the ultrasonic transducer frequency. The control and evaluation device 7 further serves, after transmission of the transmission signals received signals of the ultrasonic transducer 6 to receive this upon receipt of ultrasonic waves, in particular an ultrasonic pulse such as one of the objects 2 discarded portion of the emitted ultrasonic pulse, forms and gives off. The control and evaluation device 7 receives the received signal and generates therefrom a runtime signal which is the transit time of the pulse from the ultrasonic transducer 6 to the object 2 and back to the ultrasonic transducer 6 reproduces. By way of example, the runtime signal can be generated upon detection of a pulse edge, so that it reproduces the runtime solely by the time of its formation or transmission.

The control and evaluation device 7 together with the ultrasonic transducer 6 represents a known device for generating a propagation time signal for determining a distance of an object by measuring the transit time of ultrasound pulses.

The control unit 8th serves to control the device. To determine the dimensions of the parking space 3 she feels as she passes by the objects 2 at low speed, for example at a speed of less than 30 km / h, the area laterally of the motor vehicle 1 in relation to existing objects there 2 from which they periodically take measurements in a direction transverse to the vehicle's longitudinal axis 5 performs. For this purpose, it gives each a start signal to the control and evaluation 7 then send signals to the then serving as an ultrasonic source ultrasonic transducer 6 sends to deliver an ultrasonic pulse. After delivery of the pulse, the ultrasonic transducer converts 6 upon receipt of ultrasonic waves, these receive signals to the control and evaluation 7 be transferred, where this forms a runtime signal from the received signals and to the control unit 8th emits. The control unit 8th determined from the runtime signal using the ultrasonic velocity in air from the running time the distance d. The repeated measurements during passing give a depth profile of a corresponding number of measurements, which is the respective distance of detected objects as a function of the position in the direction of travel, using the speed of the motor vehicle 1 is determined.

Following this, an automatic parking of the motor vehicle 1 done when the control unit 8th by comparison with corresponding data stored in it has detected that the parking space 3 big enough for automatic parking.

The However, known distance detection system has the near portion that the range of the device for generating the runtime signal for the practical Use too low, in the example less than 4 m, is.

In 2 the motor vehicle is different 1' from the motor vehicle 1 in 1 only in that, instead of the known device for generating a propagation time signal for a determination of a distance of an object by measuring the transit time of ultrasound pulses, a corresponding device according to a first preferred embodiment of the invention is replaced. For all unchanged parts, therefore, the same reference numerals are used and the explanations also apply here accordingly.

The device for generating a runtime signal for determining a distance of an object by measuring the transit time of ultrasound pulses in turn comprises a control and evaluation device 9 and a converter module 10 that in a holding device 11 two arranged at a predetermined distance a from each other, via signal connections to the control and evaluation 9 connected ultrasonic transducers 12 and 13 having. The distance a of the ultrasonic transducer 12 and 13 transverse to the main emission direction in this embodiment is less than 20 wavelengths, more preferably 5 wavelengths, of the ultrasonic waves in air, namely about 5 mm.

The holding device 11 , In the example serving as a housing plastic injection molded part, from a the transmission of ultrasonic waves inhibiting plastic, has two shots 14 and 15 with decoupling rings for receiving the conventional ultrasonic transducer 12 and 13 ,

The ultrasonic transducers 12 and 13 are constructed in a known manner and each have a plastic housing with an aluminum membrane, on the inside of a piezoceramic disk is glued, which in turn is variable by corresponding transmission signals in their extension, which excites by the connection with the last membrane. Conversely, when the diaphragm is excited with ultrasonic waves, the piezoceramic disk emits received signals by means of a corresponding action of force on the disk.

The converter module 10 with the ultrasonic transducers 12 and 13 is further formed so that the emission or reception areas directly from the aluminum membrane of the ultrasonic transducer 12 respectively. 13 are substantially smooth and have no protruding ultrasound-bundling devices, in particular no tubes with dimensions greater than half a wavelength in the emission direction, are arranged or sunk into such. This allows a good integration into the body design and avoids hard-to-remove contamination during operation.

The converter module 10 is so on the motor vehicle 1' attached that a connecting line through the ultrasonic transducer 12 and 13 at least approximately parallel to the vehicle longitudinal axis 3 and the roadway on which the motor vehicle is aligned.

The control and evaluation device 9 is now adapted to start signals of the controller 8th the ultrasonic transducers 12 and 13 so as to control as ultrasonic sources or output from the ultrasonic transducers receive signals so that the method described below is carried out according to a first preferred embodiment of the invention.

The control and evaluation device 7 indicates the receipt of a start signal from the controller 8th Transmission signals to the two ultrasonic transducers 12 and 13 so that they emit a pulse of ultrasonic waves of the same predetermined frequency with a fixed predetermined phase relationship. In this first exemplary embodiment, the ultrasound waves are emitted in phase, ie with a predetermined phase shift of 0 °.

The ultrasonic transducers 12 and 13 each have a radiation and reception characteristic, that of the ultrasonic transducer 6 equivalent. Because both ultrasonic transducers 12 and 13 When ultrasound sources emit ultrasound waves of the same frequency with the predetermined phase shift, ultrasound waves of the same frequency with a predetermined phase relationship are emitted from two acoustically separated locations at a predetermined distance a from one another, so that they interfere with each other in an interfering manner. This results in the in 2 indicated by dotted lines transmission characteristic of the overall arrangement in which arise by interference at least three transmission lobes, of which the average with the maximum intensity at an angle of about 90 ° with the line connecting the vehicle 1' forming main end lobe 16 is.

The shape of the main end lobe 16 and the angles between the main end lobe 16 and the sidelobes 17 depend on the ratio of wavelength and distance a. The distance a is preferably selected depending on the wavelength used so that the angle between the main lobe 16 and the sidelobes 17 is as large as possible, so that objects only possible through the main lobe 16 with sufficient intensity for reception.

By training the main end lobe 16 a much greater range is achieved than when using a single ultrasound source as in 1 ,

The control and evaluation device 9 switches to reception after delivery of the ultrasonic pulse and receives in this embodiment, receive signals of the ultrasonic transducer 12 this by transforming one of one of the objects 2 forms and gives back reflected portion of the emitted ultrasonic pulse.

The control and evaluation device 9 determines the position of the pulse edge of the reflected pulse portion and forms a corresponding runtime signal, which sends it to the control unit 8th gives off this as in the known distance detection system 4 in 1 further processed.

In a second embodiment, only the control and evaluation device 9 replaced by a control and evaluation, which is different from the control and evaluation 9 differs in that it only one of the ultrasonic transducers, such as the ultrasonic transducer 12 , by supplying corresponding transmission signals as an ultrasonic source for an ultrasonic pulse drives. This essentially functions as the one in 1 ,

After delivery of the ultrasonic pulse, however, receive signals of both ultrasonic transducers 12 and 13 received and evaluated in consideration of the phase relationship between these and a predetermined phase relationship, in this embodiment 0 °.

Ultrasonic waves emanating from one of the objects are therefore simultaneously received at two locations separated acoustically from one another at a predetermined distance a and having different reception phases with the formation of reception signals. The control and evaluation device evaluates these received signals in dependence on each other and the predetermined phase relationship to form the runtime signal. In this case, a fixed phase position of the received signals, corresponding to the phases of the ultrasonic waves on the surfaces of the ultrasonic transducers, in the example of 0 °, is assumed. The two ultrasonic transducers 12 and 13 Therefore, together with the control and evaluation device form a receiving device whose receiving characteristic corresponds to the transmission characteristic in the first embodiment. It becomes so in the main reception lobe, which the main end lobe 16 corresponds to an increased sensitivity, so that here too the range of the overall arrangement is increased.

A third embodiment differs from the first and second embodiments again only by the design of the control and evaluation 9 , This is now designed so that they each have the same two ultrasonic transducers, ie the ultrasonic transducers, for emitting the ultrasonic waves and for receiving the ultrasonic waves 12 and 13 used. This means that the control and evaluation device for emitting the ultrasonic waves is designed like the control and evaluation device of the first embodiment and for the formation of the runtime signals such as the second embodiment. In this case, the same phase relationship or phase shift is assumed for the emission as well as for the reception.

In this embodiment, not only results in a particularly large range, but also a particularly good directional characteristic in the detection of objects, since both the transmission and the reception characteristic is strongly directed. This directional characteristic allows it in particular with respect to the angle to the converter module 10 close to each other objects 2 to separate with greater security than is possible in the known systems.

A fourth, in 4 illustrated embodiment differs from the previous embodiments in that on the one hand, the converter module 10 opposite the vehicle's longitudinal axis 3 is arranged inclined in an angle deviating from 90 ° in the region of the front bumper and that the control and evaluation device 18 is now designed so that the phase shift in transmit and / or receive mode is adjustable. For this she has a device 19 for shifting the phases of the transmission signals or the reception phases of the received ultrasonic waves by a predetermined phase shift, via a corresponding input or a corresponding interface of the control unit 8th is adjustable. This device 19 For example, it may include an electronic circuit that allows for an adjustable phase shift. Thus, the predetermined phase shift between the emitted ultrasonic waves is generated or receiving phases of the received ultrasonic waves are shifted by the predetermined phase shift to each other.

The value for the phase shift is selected so that the maximum of the emitted intensity of the superposed ultrasonic waves, ie the maximum of the main lobe lies in one direction, or the maximum sensitivity of the receiving characteristic is in a direction opposite to a connecting line between the ultrasonic transducers 12 and 13 , ie the two transmitting or receiving locations, is inclined.

In the exemplary embodiment, the phase shift is chosen in particular such that the maximum of the main transmitting lobe 16 at least approximately orthogonal to the vehicle longitudinal axis 5 is aligned, although the converter module 10 differently oriented. There is therefore an electronic pivoting of the transmission or reception characteristic.

This has the advantage that a readjustment of the alignment of the transmission and reception characteristics is simply possible purely electronically without mechanical changes, and that a great deal of freedom in the choice of the installation location on the vehicle 1 consists.

Other embodiments differ from the embodiments described above in that the device is also set up to detect positions and distances in the near range. For this purpose, only the control and evaluation device needs to be modified so that a corresponding control signal of the control unit 8th to measure the distance in the near field of one of the ultrasonic transducers 12 or 13 Ultrasonic waves emitted for a pulse transit time measurement and of the other ultrasonic transducer 13 portions of the ultrasonic waves reflected from the object are received. In this case, the control and evaluation device can in particular receive signals from the ultrasonic transducer serving as a receiver 13 already received during the delivery of an ultrasonic pulse, so that even very short terms and thus distances can be detected.

at a further embodiment are the control unit and the control and evaluation device designed so that Measurement of the position of the object in the near field successively from each one of the two ultrasonic transducers ultrasonic waves for a pulse transit time measurement emitted and reflected from the object portions of the ultrasonic waves received and corresponding pulse transit times are determined, and from the pulse transit times by means of triangulation data are determined that reflect the location of the object.

alternative can the control unit and the control and evaluation device be designed so that for measuring the position of the object in the near field one after the other respectively ultrasonic waves of a pulse transit time measurement at one of the at least two locations received and corresponding pulse transit times are determined, and be determined from the transit times by means of triangulation data, that reflect the location of the object.

A converter module 20 for a device according to yet another embodiment of the invention, which in itself constitutes an invention, differs from the transducer module 11 in that only one ultrasound source serving as ultrasonic transducer 21 is provided, but before a mask or aperture 22 For example, given by a housing 23 with at least two openings arranged at a predetermined distance from one another 24 is arranged from a highly intransparent, preferably absorbing material for ultrasound of the frequency used.

The corresponding control and evaluation device is compared to the control and evaluation of the first embodiment changed insofar as it now needs to deliver only to the one ultrasonic transducer transmit signals, whereupon this generates ultrasonic waves, but only the openings 24 the aperture 22 be delivered. In this way, with only one ultrasonic transducer also a delivery of ultrasonic waves of two acoustic waves for acoustic separated from each other, at a predetermined distance a spaced apart locations can be achieved. The ultrasonic waves may then interfere in the far field like the ultrasonic waves of the first embodiment.

1, 1'

motor vehicle

2

objects

3

parking lot

4

Distance detection system

5

vehicle longitudinal axis

6

ultrasound transducer

7

Tax- and evaluation

8th

control unit

9

Tax- and evaluation

10

converter module

11

holder

12

ultrasound transducer

13

ultrasound transducer

14

admission

15

admission

16

Main transmission lobe

17

side lobes

18

Tax- and evaluation

19

Facility for shifting phases

20

converter module

21

ultrasound transducer

22

mask

23

casing

24

openings

a

distance

d

distance

Claims (24)

Method for generating a runtime signal for determining a distance of an object ( 2 ) by measuring the transit time of ultrasonic powder sen, in which at least two at a predetermined distance from each other acoustically separated locations simultaneously ultrasonic waves are radiated at the same frequency with a predetermined phase relationship to each other, so that they overlap interfering and form at least one ultrasonic pulse, and / or at which of the object ( 2 ) outgoing ultrasonic waves simultaneously at two acoustically separated from each other at a predetermined distance locations ( 12 . 13 ) are received to form receive signals and the received signals are evaluated in dependence on each other to form the runtime signal. Method according to Claim 1, in which the same ultrasound transducers are used to emit the ultrasound waves and to receive the ultrasound waves ( 12 . 13 ; 21 ) to be used. Method according to one of the preceding claims, in which the distance between the at least two locations ( 12 . 13 ) is less than 20, preferably 10 wavelengths, more preferably 5 wavelengths, of ultrasonic waves in air. Method according to one of the preceding claims, in a predetermined phase shift between the delivered Ultrasonic waves is generated or receiving phases of the received Ultrasonic waves around a given phase shift to each other be moved. Method according to one of the preceding claims, in which the value for the phase shift is chosen such that the maximum of the emitted intensity of the superimposed ultrasonic waves lies in a direction opposite to a connecting line of the at least two locations ( 12 . 13 ) is inclined. Method according to one of the preceding claims, in which the value for the phase shift is selected such that the maximum of the reception sensitivity for reception at the two locations ( 12 . 13 ) and the common evaluation lies in a direction opposite to a connecting line of the at least two locations ( 12 . 13 ) is inclined. Method according to one of the preceding claims, in a value for the phase shift is detected or determined and used. Method according to one of the preceding claims, in which for measuring the distance in the near field from one of the locations ( 12 . 13 ) Transmitted ultrasonic waves for a pulse transit time measurement and at another of the locations ( 12 . 13 ) of the object ( 2 ) reflected portions of the ultrasonic waves are received. Method according to one of the preceding claims, in which for measuring the position of the object ( 2 ) in the near field successively from each of the two places ( 12 . 13 ) Transmitted ultrasonic waves for a pulse transit time measurement and from the object ( 2 ) received portions of the ultrasonic waves and corresponding pulse transit times are determined, and from the pulse transit times by means of triangulation data are determined, the position of the object ( 2 ) play. Method according to one of the preceding claims, in which for measuring the position of the object ( 2 ) in the near field one after another in each case at one of the at least two locations ( 12 . 13 ) Ultrasonic waves of a pulse transit time measurement received and corresponding pulse transit times are determined, and from the transit times by means of triangulation data are determined, the position of the object ( 2 ) play. Device for generating a runtime signal for determining a distance of an object ( 2 by measuring the transit time of ultrasound pulses, comprising: at least two ultrasound sources arranged at a predetermined distance from each other ( 12 . 13 . 21 ) with a smooth radiation range, which convert the transmission signals into ultrasonic waves and emit the ultrasonic waves so that they interfere with each other in an interfering manner, and a control and evaluation device ( 9 ; 18 ), which is designed to transmit signals for the at least two ultrasound sources ( 12 . 13 ; 21 ) and at the same time emit ultrasonic waves having the same frequency and predetermined phase relationship, and at least one received signal from at least one ultrasonic transducer having at least one of the at least two ultrasonic sources and / or another ultrasonic transducer received by conversion from the object ( 2 ) reflected ultrasonic waves is received, and to evaluate the formation of the runtime signal. Apparatus according to claim 11, wherein the at least two ultrasound sources ( 12 . 13 ) each have at least one ultrasonic transducer, which is also designed as an ultrasonic receiver, which converts received ultrasonic waves into received signals and emits them, and in which the control and evaluation device ( 9 ; 18 ) is further configured to receive the received signals of the at least two ultrasonic transducers ( 12 . 13 ) and shared in the evaluation. Apparatus for generating a runtime signal for determining a distance of an Ob object ( 2 by measuring the transit time of ultrasound pulses, comprising: at least two ultrasound transducers arranged at a predetermined distance from each other ( 12 . 13 ; 21 ) with a smooth receiving area, which are adapted to receive ultrasonic waves, to convert them into received signals and to emit the received signals, and a control and evaluation device ( 9 ; 18 ) which is adapted to transmit signals for at least one ultrasound source ( 12 . 13 ; 21 ), which comprises at least one of the ultrasound transducers and / or a further ultrasound transducer, so that the at least one ultrasound source ( 12 . 13 ; 21 ) radiates certain ultrasonic waves through the transmission signals, and reception signals of the at least two ultrasonic transducers ( 12 . 13 ; 21 ), which are formed by converting received, reflected by the object reflected ultrasonic waves, and to evaluate together to form the propagation time signal. Device according to Claim 13, in which the at least two ultrasonic transducers ( 12 . 13 ; 21 ) are also formed as ultrasonic sources which emit certain ultrasonic waves in response to transmission signals through the transmission signals, and in which the control and evaluation device ( 9 ; 18 ) is further adapted to the transmission signals for the at least two ultrasonic transducers ( 12 . 13 ; 21 ) and deliver, so that they simultaneously deliver ultrasonic waves with the predetermined frequency and predetermined phase relationship. Device according to one of claims 11 to 14, wherein the distance of the at least two ultrasonic sources ( 12 . 13 ; 21 ) or ultrasonic transducer smaller than 20, preferably 10 wavelengths, particularly preferably 5 wavelengths, the ultrasonic waves in air. Device according to one of Claims 11 to 15, in which the at least two ultrasound sources or ultrasound transducers ( 12 . 13 ; 21 ) in a single holding device ( 11 ; 23 ) are held. Device according to one of Claims 11 to 16, in which a device ( 19 ) is provided for shifting the transmission phases of the ultrasonic waves to be transmitted to each other, by means of which a predetermined phase shift between the transmitted ultrasonic waves is generated. Device according to Claim 17, in which the value for the phase shift is selected such that the maximum of the radiated intensity of the superposed ultrasonic waves of the at least two ultrasonic sources ( 12 . 23 ; 21 ) lies in a direction opposite to a connecting line of the at least two ultrasonic sources ( 12 . 13 ; 21 ) is inclined. Device according to one of Claims 12 to 18, in which a device ( 19 ) is provided for shifting the reception phases of the received ultrasonic waves by a predetermined phase shift to each other. Device according to Claim 19, in which the value for the phase shift is chosen such that the maximum of the receiving sensitivity of the device lies in a direction opposite to a connecting line of the at least two ultrasonic transducers ( 12 . 13 ; 21 ) is inclined. Device according to one of Claims 11 to 20, in which the control and evaluation device ( 9 ; 18 ) is further adapted to detect or determine a value for the phase shift, and to use the determined value. Device according to one of Claims 11 to 21, in which the control and evaluation device ( 9 ; 18 ) is further configured such that for measuring the distance in the near field one of the ultrasound sources ( 12 . 13 ; 21 ) or one of the ultrasonic transducers ( 12 . 13 ; 21 ) as an ultrasonic transmitter and another of the ultrasonic sources ( 12 . 13 ; 21 ) or another of the ultrasonic transducers ( 12 . 13 ; 21 ) is operated as an ultrasonic receiver for a pulse transit time measurement. Device according to one of Claims 11 to 22, in which the control and evaluation device ( 9 ; 18 ) is further configured so that for measuring the position of the object ( 2 ) in the near field successively each one of the ultrasound sources ( 12 . 13 ; 21 ) is operated as an ultrasonic transmitter for a pulse transit time measurement, and from the transit times by means of triangulation data are determined, which determines the position of the object ( 2 ) play. Device according to one of Claims 11 to 23, in which the control and evaluation device ( 9 ; 18 ) is further configured so that for measuring the position of the object ( 2 ) one after the other in the near field one of the ultrasonic transducers ( 12 . 13 ; 21 ) is operated as an ultrasonic receiver for a pulse transit time measurement, and from the transit times by means of triangulation data are determined, which determines the position of the object ( 2 ) play.