DE102005041912A1 - Data transmission system for a motor vehicle, to trigger passenger protective systems on an impact, has side and frontal sensors transmitting to a control without synchronization and with independent time bases - Google Patents

Abstract

The data transmission system in a motor vehicle (1) between a sensor transmitter (2.1,2.2) and a receiver (3) at a central control unit, with no direct synchronization between them, is for use to trigger the safety systems to protect the occupants on an impact collision. The sensors transmit data streams (2.1.1,2.2.1) from the side and the front of the vehicle. The transmitters and the receiver have independent time bases for each to generate an individual time interval. The transmitters transmit a defined number of data protocols for each fixed time interval. The received data are given a time stamp at a receiver interface. An interpolated or extrapolated data value is derived and produced on scanning the data from the interface, from a given number of time-stamped data stored intermediately at the interface.

Description

The The invention relates to a method for data transmission according to the preamble of claim 1.

Around the security for Road users in traffic to improve are reinforced Occupant protection systems with ever higher performance in vehicles built to the occupants of a vehicle as optimally as possible in every conceivable Accident situation / driving situation protect / support too can. These include especially accident situations that are not a simple frontal impact but accident events that, for example, as a result of of the accident obstacle (pedestrian or Tree = pole crash) or the impact angle (oblique or Side crash), a unique crash detection often difficult allow, there the crash acceleration signals generated by the crash, often are very low in amplitude or due to a soft vehicle body from Central control unit, which is preferably located on the center tunnel, relatively heavy can be detected or where a quick reaction is required by the central device alone no longer guaranteed can be.

Just in these accidents or accident types in which the crumple zone is often very low is (e.g., page crash) or the obstacle (e.g., pedestrian) only one relatively low Mass possesses, however, is a quick and safe sensing and detection of crash-generated signatures of the utmost importance, hence relative fast and safe a trigger signal for the Protective devices can be generated.

Around To achieve an improvement here, one has gone to To create systems in which so-called assistance sensors (side sensors / up-front sensors) with the most varied principles of action, such as printing borne and acceleration sensors, as close as possible placed on the spot to be as possible to be able to quickly detect an impact and the central unit, which preferably placed in the middle of the vehicle, continue reporting to be able to.

The consideration Information from assistance sensors to form a triggering criterion is already known from numerous writings.

From the DE 44 25 846 A1 For example, a method for deploying side airbags of a safety device for motor vehicles is known in which the information of the acceleration sensor (s) arranged centrally in the vehicle is linked to the information from side satellites in order to derive a triggering signal from the linked evaluation of the information. Each of the sensor signals is checked to see if it exceeds predetermined thresholds, and according to the exceeded thresholds, the signal is classified into an acceleration class. The class assignment of the sensor signals is evaluated by means of an evaluation matrix and, depending on the result of the evaluation, optionally a trigger signal is generated. The triggering matrix determines which combination of the detected accelerations leads to a trigger signal and in which combinations no triggering of the restraint means takes place.

From the DE 101 14 277 C1 a device for detecting a side impact in a motor vehicle is known, in which with a central acceleration sensor and outsourced acceleration sensors, which are arranged on the vehicle sides, with a data processing device a triggering decision, by / on the basis of the signatures of the acceleration sensors, is generated to control the protection means ,

From the DE 197 40 021 A1 a device for occupant protection in a motor vehicle is known, which comprises in addition to a central control unit with an impact sensor unit, a plurality of decentralized symmetrically arranged impact sensor units. The signals of the impact sensor units are used to trigger an occupant protection device, wherein the signals of the individual impact sensor units can be used as a triggering signal and / or as a plausibility check of the triggering decision.

From the DE 198 21 500 A1 a control device and a control arrangement for an occupant protection means of a motor vehicle and a method for transmitting data in the control arrangement is known. The outsourced sensors are in this case attached, for example, to a vehicle side part or to a vehicle cross member.

However, all these systems have the disadvantage, or in all the disclosed methods, it is tacitly assumed in each case that the data / information of the assisting sensors involved can automatically be received correctly, without any data loss, in the central control unit. Unfortunately, this assumption, taken for granted, does not always apply on closer inspection, especially if the units involved in the data transmission have independent system clocks / system time bases, so that there is no direct synchronization between the units involved at least not in the complete data chain between the data acquisition in the assistant sensor and the data processing (algorithm) in the central control unit.

Though m interfaces for data transfer with buffer registers are used today, so that the sampling times, or better said, the data transfer times synchronized with exactly the time of entry into the register Need to become, however, it is the time reference of the transmitted data protocols lost and may be mismatched Frequency of system clocks of transmitter and receiver enter the situation that at certain data transfer dates too many or too few data logs in the registers are. For example, if the registers are structured as a FIFO shift register, would be at the time intervals, which exceptionally more data logs fall into a time interval, the oldest data protocol before its adoption overwritten from the register again. There usually related to the transit time differences between sender and receiver on the data transfer speed are only changing relatively slowly, These override effects occur periodically open and lead thus a periodic error in the transmitted sensor signal, which to the fatal tripping possibly just decision-relevant signal components can lead.

In the prior art, for example. The DE 19732873 A1 Although methods of bitwise synchronization of the data stream are known in which the satellite data transmission device, ie the outsourced sensor or, alternatively, in the central device, that is to say the receiver, the data transmission clock or the data transmission clock are adapted to one another. However, this requires tunable clock generators and corresponding clock adjustment loops, which are technically complex and costly.

The Object of the present invention is therefore to provide a method for data transfer between a transmitter and a receiver, where no direct synchronization between the units involved is available,,.

These Task is performed according to the characteristics of patent claims 1 solved. Advantageous developments of the invention will become apparent from the Dependent claims, including combinations and developments of individual features are possible with each other.

One essential idea of the invention is that the non-existent Synchronization of the participating units is compensated by by quasi in the interface between the units involved a "substitute synchronization" of the data / information / information content is made, which is characterized in that in the receiver on Basis of the received / determined data protocols per time unit Recipient, a temporal assignment of the location, the data protocols sent by the transmitter, to that of the recipient expected sampling occurs. So it's going to be a procedure for data transmission an unsynchronized data stream between a transmitter in particular a satellite, so a outsourced from the central unit sensor, and a receiver a central control unit in a car safety application described.

at the transmission the data between the sender and the receiver is not direct, So bitwise synchronization between the units involved, because the transmitter and the receiver independent from each other Time bases for generating a separate internal time interval have.

The Time interval is by a certain number of system clocks defined by the respective time base and can already be due to the different Time base thus be different between sender and receiver.

Even if, in the ideal state, the same time intervals between transmitter and receiver are provided under must real technical conditions with a detuning of the clock generator from transmitter and / or receiver be calculated, whether by aging of the components or temperature influences. This leads earlier or later to the situation that in the receiver side Time interval more or less data logs arrive than expected.

Of the Sender therefore sends one per defined time interval of the transmitter defined number of data protocols, wherein the data logs in equidistant Periods of regular Repeat time interval to time interval (of the transmitter).

One Data protocol consists of one or more data words and the usual headers, like address bits, and check bits, so in any case a plurality of bits.

The whole procedure thus works on the level of temporal assignment and evaluation of the data protocols and not on the physical bitwise synchronization.

The system clocks of sender and receiver can run independently of each other within technically reasonable limits. It only has to be ensured that the individual data bits of the Sen ders receivable from the receiver at all, which is technically easy to ensure thanks to conventional oversampling.

It So there is no bitwise synchronization but just one Synchronization of data logs in terms of their temporal Location in the data stream.

The temporal allocation allows the central device then back to the data logs with their correct time reference to merge a data stream or to process them in the correct temporal relation to one another.

The temporal assignment of the individual data values from the data protocols allows an adaptation of the data values to the desired sampling time (s) or desired data transfer times (s). This adaptation preferably takes place by means of an interpolation the desired Data transfer times. In addition, you can Dropouts in the data transfer be detected and bridged by interpolation or extrapolation.

The fact that there is a lack of temporal allocation of the location of the data protocols / protocol contents sent by the transmitter to the sampling times expected by the receiver, to occasional data losses due to over- or undersampling of the units involved in the communication / transmission or in the subsequent data processing, is closer on the basis of the 2 easily seen.

through the so-called replacement synchronization according to the invention the data / information / information content, quasi in the interface between the participating units, it is guaranteed that the inevitably during a asynchronous data transfer / one asynchronous interface traffic problems can be and at any time can be ensured that no data loss / loss of information while the transmission, involved in which units with different system clocks are, can occur.

Further Advantages and applications The present invention will become apparent from the following description in connection with the embodiment shown in the figures on a motor vehicle / passenger car.

In the description, in the claims, in the abstract and in the accompanying drawings the in the list below the reference numbers used terms and associated reference numerals used.

The Invention will now be described below with reference to an embodiment with the aid closer to the figures explained. In the following you can for functional same and / or same elements with the same reference numerals be designated.

It demonstrate

1 A basic possible arrangement of an occupant protection system for a motor vehicle according to the prior art, consisting of a central device and the associated assistance sensors.

2 : A schematic representation of a chronological sequence, the data / information sent by the sender within its data frame, and the information that can be received by the receiver (control unit) within its data frame for further processing.

3 : A schematic representation of a time sequence, according to 2 , supplemented with the possible tolerances or time offsets which the transmitted data can accept / have due to the two asynchronous system clocks (if only the data arriving in an interval is taken into account).

4 : A schematic representation of the transmission link or the units involved in the transmission.

5 : A schematic representation of the preparation of the data protocols or the data values contained in the data protocols, which are temporarily stored in the receiver interface, and are provided here with a time stamp or a time stamp.

6 : A schematic representation of the transmission link, or the units involved in the transmission, and the delay times.

1 shows in principle possible arrangement of an occupant protection system for a motor vehicle according to the prior art, consisting of a central device and the associated assistance sensors.

The central device ( 2 ) is centrally located in the vehicle ( 1 ), preferably on the tunnel of the vehicle. By means of this central device ( 2 ), the non-illustrated occupant restraint means, such as belt tensioners, airbag and rollover protection devices are connected, which are to be activated in the event of an accident or a critical situation, temporally at the optimal right time, so that the vehicle be protected as efficiently as possible or the vehicle occupants by the existing protective devices.

At the side of the vehicle ( 1 ) arranged assistant sensors ( 2.1 ) are so-called side sensors, which are mainly to support the evaluation of a side impact or an accident situation in which the force is mainly from the side or perpendicular to the / to the vehicle longitudinal axis required, so a related accident characteristics at an early stage can be detected to act accordingly, or to activate the required occupant protection devices.

At the front of the vehicle ( 1 ) arranged assistant sensors ( 2.2 ) are so-called upfront sensors, which are mainly to support the evaluation of a so-called pile crash or an accident situation in which the force is mainly from the front or parallel to the vehicle longitudinal axis required, so a related accident characteristics at an early stage can be detected to act accordingly, or to activate the required occupant protection devices.

As can be further seen from the figure, the assistance sensors ( 2.1 . 2.2 ) one data protocol / data stream each ( 2.1.1 . 2.2.1 ), consisting of the data words 2.1 , 1.1 . 2.1 , 1.2 etc., to the central unit / receiver ( 3 ), wherein this transmission mode can be a transmission mode with equidistant gaps (pauses) (data word → equidistant pause → data word → equidistant pause → data word → ....).

2 shows a schematic representation of a temporal sequence, the data / information sent by the transmitter within its data frame, and the receiver within its data frame receivable information for further processing.

In The upper representation of the figure is the transmission clock / time slice an assistant sensor / satellite, with the time slice the satellite takes a cyclic duration of typically 225 μsec, so that in terms of time this equidistant time periods which form regularly from Repeat time interval to time interval. Each in the middle the time interval is a data transmission of the assistant sensor shown (arrow down).

In the lower illustration of the figure, the receive clock / time slice from the receiver ( 3 . 3.2 ), wherein the time slice 250 microseconds or with respect to the further processing of the data is 500 microseconds, so that typically at each time slice of the receiver at least two of the assistant sensor / satellite sent data information is available, or can be evaluated. Due to the deliberately different selected time frame duration, the tolerances of the system clocks (eg, quartz tolerances & resonator tolerances) can be taken into account, so that even with an unfavorable tolerance ratio it can still be ensured that at least two current ones of the assistant sensor / satellites are safe for each time slice of the receiver sent data infor- mation is available or can be evaluated. As can also be seen from the figure, as a result of the deliberately different selected time periods, occasionally also three data transmissions sent by the assistance sensor / satellite become available within a time slice of the receiver, or are available for evaluation (center of the image).

Further, from the representation, the time base of the receiver interface ( 3.1 ). Using the receiver interface ( 3.1 ) and the data processing according to the invention taking place there, preferably with an interpolation method and / or in addition with an extrapolation method, to compensate for the delay times resulting from the transmission, one achieves the intended goal of providing a method for synchronizing a data stream between a transmitter and a receiver in which there is no direct synchronization between the participating units, which reconstructs the temporal assignment of asynchronously arriving data / data words.

3 shows a schematic representation of a temporal sequence, according to 2 , supplemented with the possible tolerances or time offsets which the transmitted data can assume / have due to the two asynchronous system clocks.

Similar to in 2 are in 3 again the equidistant time intervals which differ from one another by the transmitter and receiver can be seen. As can further be seen from the figure, the "transmission times" of the transmitter can vary with a certain tolerance or time offsets within a reception interval of 500 μsec of the receiver, the size of the tolerance being decisive for the number of data protocols, per time interval of the receiver , is determined.

The specified ranges of values with regard to the possible tolerance ranges arise here arithmetically, and are easily traceable in accordance with the basic arithmetic operations of addition and subtraction or verifiable.

As from the figure, the figure shows a representation, in this case the time intervals of the transmitter ΔtS1, ΔtS2, ΔtSn (a)) as well as the equidistant Time intervals of the receiver ΔtE1, ΔtE2, ΔtEn (c)) largely in equidistant Time intervals are available. This far-reaching agreement the equidistant Time intervals, or a direct match of the equidistant However, time intervals are for implementing the inventive concept not mandatory (b) and d)).

4 shows a schematic representation of the transmission line, or involved in the transmission units.

As can be seen from the figure, from the satellites ( 2.1 ) to the recipient ( 3 ) the data protocols ( 2.1 , 1.2 . 2.1 , 1.1 ) Posted. In the receiver ( 3 ), these data protocols or the contents of the data protocols are sent to a receiver interface ( 3.1 ) which supplies the data after an interpolation of the processing unit ( 3.2 ) in digital and / or analog form for further processing.

If the data provision takes place in digital form, the data transmission takes place, for example, by means of known and unspecified port interfaces (parallel or serial (SPI)). In the case of an analogue data provision, the received and processed data at the output of the receiver interface ( 3.1 ) supplied to a D / A converter, so that this analog data, the downstream processing unit ( 3.2 ) by means of whose A / D converter input can detect.

The initialization of the interpolation process of the data in the receiver interface ( 3.1 ), can be triggered by a plurality of events, such as timely by the start of the read operation of the data by the processing unit ( 3.2 ), time-delayed (in advance) with respect to the last read-out process of the data by the processing unit ( 3.2 ), or by an external signal.

The receiver interface ( 3.1 ) can be both as a separate unit (physically separated from the processing unit ( 3.2 )), and as part of the processing unit ( 3.2 ), for example, be integrated on a semiconductor and / or in an ASIC.

5 shows a schematic representation of the preparation of the data protocols or the data contained in the data records data values, which are temporarily stored in the receiver interface, and are provided here with a time stamp or a time stamp.

Like from the 5 It can be seen that the data sent by the transmitter at a distance of 225 μsec (white circles), by means of the substitute synchronization according to the invention (temporal assignment and interpolation), are converted such that at the time of polling or the polling of the receiver register of the receiver interface (FIG. 3.1 ) by the processing unit ( 3.2 ), the previously received data are interpolated in such a way, and optionally additionally extrapolated to compensate for the delay times of the transmission path, so that each time a current value is available at the time of polling.

For interpolation, the data previously received by the transmitter is used, which in the receiver interface ( 3.1 ) have been stored with a timestamp or a timestamp in order to be able to calculate the correct data value from these at the time of the query. In addition to the time interval between two data values, the time interval between them and the current time in the receiver time system can be determined, and thus the data values can be processed while taking their time position into account.

The temporal marking of the data by means of the timestamps or timestamped data, in this case both with an absolute time information, as well as with a relative time information, for example, to the next older date done. The initialization of the interpolation process of the data in the receiver interface ( 3.1 ), can be triggered by a plurality of events, such as timely by the start of the read operation of the data by the processing unit ( 3.2 ), time-delayed (in advance) with respect to the last read-out process of the data by the processing unit ( 3.2 ), or by an external signal. In this case, the readout time of the processing unit ( 3.2 ) or the external signal, as a time reference to those in the receiver interface ( 3.1 ) are used with time stamps or time stamps for determining the interpolated data value, wherein the temporal assignment of the temporal reference to the in the receiver interface ( 3.1 ) data is stored retroactively and enables an exact temporal positioning of the interpolated data value.

6 shows a schematic representation of the transmission line, or involved in the transmission units, and the delay times.

As can be seen from the figure, from the satellites ( 2.1 ) to the recipient ( 3 ) the data pro tocols ( 2.1 , 1.2 . 2.1 , 1.1 ) Posted. In the receiver ( 3 ), these data protocols or the contents of the data protocols are sent to a receiver interface ( 3.1 ) which supplies the data after extrapolation of the processing unit ( 3.2 ) for further processing. By doing extrapolation in the receiver interface ( 3.1 ), the delays, due to the signal detection, signal conversion and signal transmission, compensated.

1

motor vehicle

2.1

Transmitter / sensor assistant, especially side sensor

2.1.1

data stream from the side sensor / data word from the side sensor

2.1.1.1

data word n

2.1.1.2

data word n + 1

2.2

Transmitter / sensor assistant, especially upfront sensor

2.2.1

data streams from the upfront sensor

3

Receiver / central control unit

3.1

receiver interface

3.1.1

D / A converter of the receiver interface with interpolator

3.1.2

Register / time clocked Stack / Timed Memory Area

3.2

uP / processing unit / algorithm

3.2.1

A / D converter the processing unit

Claims (12)

Method for data transmission between a transmitter ( 2.1 . 2.2 ) of a sensor and a receiver ( 3 ) of a central control unit in a motor vehicle security application, wherein in the transmission of data ( 2.1.1.x . 2.2.1.x ) between the transmitter ( 2.1 . 2.2 ) and the recipient ( 3 ) there is no direct synchronization between the units involved, characterized in that a) the transmitter ( 2.1 . 2.2 ) and the recipient ( 3 ) have independent time bases for generating their own internal time interval, b) the transmitter ( 2.1 . 2.2 ), a defined number of data protocols (per 2.1.1.x . 2.2.1.x ), c) in a receiver interface ( 3.1 ) the received data ( 2.1.1.x . 2.2.1.x ) are provided with a time stamp, and d) when the data is read from the receiver interface ( 3.1 ) an interpolated or extrapolated data value from a certain number of previously in the receiver interface ( 3.1 ) is generated and output with timestamp of cached data. Method for data transmission according to claim 1, characterized in that the time stamp is a Absolute time information is. Method for data transmission according to claim 1, characterized in that the time stamp is a Relativzeitinformation, for example, to the next older timestamp acts. Method for data transmission according to claim 1 to 3, characterized in that the interpolation process in the receiver interface ( 3.1 ) as a result of the beginning of the read-out operation of the data by the processing unit ( 3.2 ) is initiated. Method for data transmission according to claim 1 to 3, characterized in that the interpolation process in the receiver interface ( 3.1 ) is initiated with respect to the previous read-out process. Method for data transmission according to claim 1 to 5, characterized in that the readout time of the processing unit ( 3.2 ) as a time reference to those in the receiver interface ( 3.1 ) data stored with time stamps serves to determine the interpolated data value. Method for data transmission according to claim 1 to 5, characterized in that an external signal, for example from the processing unit ( 3.2 ) as a time reference to those in the receiver interface ( 3.1 ) data stored with time stamps serves to determine the interpolated data value. Method for data transmission according to claim 6 and 7, characterized in that the temporal assignment of the temporal reference to the in the receiver interface ( 3.1 ) stored data is retroactive. Method for data transmission according to claim 8, characterized in that the retroactive temporal assignment an exact temporal positioning of the interpolated data value allows. Method for data transmission according to Claim 1 to 9, characterized in that one by the transmission resulting phase difference, preferably by extrapolation, is compensated. Arrangement for data transmission according to claim 1 to 10, characterized in that, in a preferred embodiment, the receiver interface ( 3.1 ) is integrated as a separate unit, for example on a semiconductor and / or in an ASIC, and physically separated from the processing unit ( 3.2 ). Arrangement for data transmission according to claim 1 to 10, characterized in that, in egg ner preferred embodiment, the receiver interface ( 3.1 ) as part of the processing unit ( 3.2 ) is integrated on a semiconductor and / or in an ASIC.