DE10040511A1 - Automobile safety-critical measurement detection system has at least 2 independent measuring channels provided with independent sensors - Google Patents

Abstract

The detection system has at least 2 independent measuring channels,provided with independent sensors and elements for detecting an error function or malfunction of the measuring channels. The measuring channels are operated in parallel in an active stand-by mode, with unlimited operation of the parallel sensors. An Independent claim for a device for detecting automobile safety-critical measurements is also included.

Description

The invention relates to an arrangement and a front direction to increase the intrinsic safety of arrangements for the detection of yaw angle movements in motor vehicle systems stemen with controlled brakes. These are, for example, au automatic driving stability control (ESP) in connection with Anti-lock braking systems (ABS), traction control systems (ASR) and steering corrections but also systems for autonomous Ab level control (AICC) or for collision avoidance.

Driving stability regulations (ESP) for control and limitation unwanted yawing movements around the vertical axis are knows. Here, with the help of sensors variables that are deliberately changed by the driver and from this a target yaw rate is calculated. They are the Steering angle, the accelerator pedal position, the brake pressure, the cross acceleration as well as the turning behavior of the individual driving stuff wheels. At the same time, the actual value of the yaw rate, the sets in response to the driving maneuver with one Yaw rate sensor measured. Deviates the actual value of the yaw movement supply from the calculated setpoint over a predetermined, the Driving stability endangering degree, is targeted by Brake and engine intervention the yaw movement to allowable Values limited.  

A high level of functional reliability must be ensured by the sensors long because their malfunctions U. Brakes / braking cause at the wrong time and thus dangerous Can bring about situations. This applies in particular to the yaw rate sensor, which already has a moderate overrun permissible drift tolerances for accuracy and precision precision can lead to undesired control processes. Even though the impact of these control processes through the use of others Auxiliary variables, causalities or plausibility criteria be prevails, it is currently the primary concern of the Automotive industry, the intrinsic safety of the yaw rate sensor rik so that undesirable control processes, ver caused by faulty yaw rate sensors even without others Auxiliary quantities, causalities or plausibility criteria si be excluded. Motor vehicle (Kfz) - State-of-the-art yaw rate sensors already have a high level of intrinsic safety and are constructed so that the vast majority of all Cases become recognizable as a defined total failure. It ver however, there remains a low probability that possible slowly progressing defects are not recognized. Such Defects are, for example, the result of incorrect con capacitors, open high-resistance semiconductor inputs, wac kelkontatakte etc. The probability that a sensor fails, can be used for an isolated sensor on the part of the manufacturer be specified. This so-called intrinsic safety of the However, sensors have not yet met the requirements against the automotive industry.

The need can be estimated according to the following calculation: The estimate that 10 million vehicles are produced and delivered each year and with an average operating time of 4,500 hours per vehicle leads to a required failure rate of the yaw rate sensor of around 10 ^-7 .

Meet conventional yaw rate sensors for motor vehicles these high demands on such a low failure probability currently not. There is therefore a loading may be a unit for yaw rate sensors with high self-sufficiency to provide security.

The invention has the objective of an arrangement or front to show direction, the application of which above schil other high requirements are sufficient.

This object is achieved by an arrangement according to An saying 1.

The inventive arrangement for the detection of safe safety-critical measured variables, in particular yaw rates and / or Acceleration data in motor vehicles, includes at least two independent measuring channels with independent Sensors and means for checking a malfunction or egg failure of the measuring channels.

In the arrangement according to the invention, the first measurement channel and the other measuring channel or channels in hot red danz operated. In the sense of the invention, this means how that it is described in more detail below that but not exactly the same sensors are used so that both sensors parallel and unrestricted, being below e.g. B. an unrestricted measuring range is understood in Operation.

Similar sensors are z. B. sol  areas that work on the same physical principle, such as vibration sensors with different resonance frequencies of the vibrating bodies or laser sensors or also sensors of all physical types that the belong to the same accuracy class.

According to the invention, the sensors used are not ge right now. They differ as detailed below is explained, at least in their basic vibration modes clearly that crosstalk from one sensor to another is prevented and external mechanical or electromagnetic cal interference does not affect the sensors in the same way impact.

Under the term "accuracy class" in the sense of the Er understood that the deviations of the measured values from Sensors in an accuracy class within a pre given accuracy interval (percentage deviation bezo to the final value displayed in a measuring range).

The different used in the present invention Redundancy terms are in Gellert, Kästner, Dr. Neuber, Lexicon of Mathematics, II Reliability Theory, page 470, publisher VEB Bibliographisches Institut Leipzig, 1985 see above as in Helm, Dr. Prang, textbook of automation technology nik, pages 88 to 90, reliability parameters / redundancy, Publisher VEB Technik Berlin, explained in 1965.

The term redundancy is used in connection with the Installation of additional elements (e.g. measuring channels) for the purpose of increasing reliability of a technical system.

One speaks of "cold redundancy" when the reserve elements (e.g. reserve channels or reserve sensors) in normal loading  are not exposed to any stress, however "hot redundancy" when the reserve elements in normal loading drove the same stresses as the work elements are subject. Cold and hot redundancy form the Borderline cases of "warm redundancy" in which the reserveele elements are stressed less than the work elements.

In the sensors that can be used according to the invention, the arrangement tion, it is preferably a first greed rate sensor, at least one further yaw rate sensor and possibly other sensors such as acceleration sensors.

The application of redundancy considerations in the field of sen Sorik in motor vehicles is reliable to increase of technical systems known per se. So in DE 195 25 217 A1 a method and an arrangement proposed with yaw rates as the input variable of a motor vehicle control system with the help of two independent measuring ka channels are obtained, of which one measuring channel the entire Measuring range, while the other channel is Measuring range is set. For error detection, the Output variables of the measuring channels on the agreement of those of the Measuring channels recorded measured variables and / or on plausibility of the Checked measurement results. The partial measuring range in Depending on the yaw process dynamically changed or as "Magnifier" used. In contrast to the present invention (Application of "hot redundancy"), uses the method DE 195 25 217 A1 a principle that the application of a corresponds to "warm redundancy". This is because in DE 195 25 217 A1 the share of the use of "hot redundancy" limited to the partial measuring range, whereby  the partial measuring channel is equipped with higher precision and is therefore used more than the second Meßka nal. Outside the partial measuring range there is "cold speech danz "because the partial measuring channel is normally unused remains, but is dynamically latent available. The invention proposed method therefore differs from method described in DE 195 25 217 A1.

In the unpublished German patent application 199 21 692.4 will an arrangement to protect electronic Functional units and / or functional groups before disturbances suggested. Here, modules with different Different sensitivity to disturbance variables Shields against the disturbances are assigned, where two or more shields for a shield with high complement their efficiency.

In the arrangement according to the invention are very general yaw rate sensors of any physical effect principle, for. B. sensors based on the application of laser light can be used. However, the yaw rate sensors used are preferably types in which the Coriolis forces occurring on the vibrating bodies under the yaw movement are used in order to draw conclusions about the yaw rate (mechanical vibration elements). Such yaw rate sensors are widely known. Cylinders, rings, disks, prisms, tuning forks, micromechanically generated structures made of silicon or quartz are used as vibrating bodies. The principle of operation of these sensors is that the vibrating body is oscillated with a constant drive amplitude and frequency in a body direction to mechanical vibrations, while under the influence of the Coriolis force at the same time a mechanical vibration is created in another body direction, the amplitude of which is proportional to the yaw rate. The vibrating bodies are excited via piezoelectric or magnetic transducer processes to oscillatory vibrations (drive) and the Coriolis reaction is scanned via similar piezoelectric or magnetic transducer processes (pick-up). If one designates the drive frequency of the oscillatory drive with f _o and the pick-up frequency of the mechanical vibration in the spatial direction of the Coriolis reaction with f _c , then the vibrating bodies are mechanically designed so that there was always a resonance frequency between the two frequencies Δf = f _o - f _c .

The yaw rate sensors with mechanical vibration elements preferably differ in that the resonance frequency sequences of the vibration elements so far apart are that the vibrations do not affect each other and vibrations impressed from the outside both yaw rates Do not or only slightly stimulate sensors.

The individual frequencies f _o and f _{c of} all redundant Gierra tensensensens to each other are then selected so that, with a common mechanical arrangement in a housing or on a common carrier, no interfering mechanical vibration couplings of the individual sensory vibrations on body and / or electrical couplings (e.g. Pull-along effects or through mechanical structure-borne noise coupling) of the oscillators or the pick-up signals occur more.

As already mentioned above, when using "hot redundancy" (in contrast to other forms of redundancy), the total failure rate (unreliability) is reduced to the product of the individual failure rates. If the failure rate of the individual motor vehicle yaw rate sensor with 70 FIT, which is equivalent to 70 × 10 ^-9 failures per operating hour, is designed to be a practically relevant value, then the required intrinsic safety is achieved with "hot redundancy" according to the invention with "hot redundancy" achieved with a failure probability of around 10 ^{-7 in the} context of 10 million equipped vehicles with a respective service life of 4500 hours.

In the arrangement there is preferably a sensor with the sensors sorelektronik connected, the output signals of electro African processing units are evaluated and it is still connected to a communication interface connection available, which with at least one central Control can be connected.

The funds report in the electronic processing unit to check the malfunction the result of the check Passing on a suitable signal to the communication Interface connection further, so that one over the commun Central controller connected to the cation interface (ESP / ECU react to a sensor failure in this way if necessary can that the operation of the arrangement continues for so long is set until the motor vehicle is in a safe Condition. Only then can the system be fully or partially be switched off (fallback concept).  

The error detection is preferably carried out in this way leads to the output variables of the individual yaw rates being so and the change behavior of these output variables continuously compared with each other in a comparison unit will be. Do the output variables and / or their ver change behavior of each other and / or of predetermined Zu Liability criteria over a temporarily valid limit from, the entry into a regulation that relates to the Yaw rate sensors support, not approved. Is located the system with (n) hot redundant channels in the control and on (n-m) channels a total occurs during control failure, the control with the remaining (m) Channels finished.

It is particularly preferred to select the frequency spacings of the individual redundant sensors Δf as follows:
In the event that two yaw rate sensors comparable in their measuring range and their precision are used, the first sensor should have the frequencies f _o1 , f _c1 with the frequency spacing Δf ₁ and the second sensor the frequencies f _o2 , f _c2 with the Have frequency spacing Δf ₂ , care being taken that the frequency spacings are chosen so that no co-channel interference (common mode interference) occurs mechanically or electrically, which could influence both yaw rate sensors at the same time.

If the frequency spacings are as described above Surprisingly, external vibration influences result se while driving through the chassis of the motor vehicle stuff on the common sensor housing or the common Act carrier, not to failure of the invention Yaw rate sensor arrangement.  

The yaw rate sensors can be called "hot speech" danz "as a function block (module) with a common enveloping housing can be arranged.

The invention therefore also relates to a device from a sealed housing with a plug, being from the sealed housing the arrangement described above voltage is included.

The sensors are preferably in an inside the housing arranged shielding inner housing or cage net.

The inner housing or the cage is expediently not galvanically connected to the sealed housing dung.

The yaw rate sensors are preferably on a first one Printed circuit board arranged and at least part of the electro African processing units is on another lei terplatte arranged.

It is useful if the first circuit board within the shielding inner housing or cage is arranged and the additional circuit board outside the shielding inner housing se or cage is arranged.

The shielding means used to protect against radiated electrical radio frequency energy prevent operated at the same time both or more in "hot redundancy" These yaw rate sensors interfere with this high-frequency energy be influenced. Similar shielding agents are used in  P 199 21 692.4. In the known device individual yaw rate sensors will act differently seed shielding cages or casings enveloped, so that sturgeon sizes, such as electromagnetic radiation, capacitive Couplings, etc., in different ways to greed rate sensors work.

According to a preferred embodiment of the invention the yaw rate sensors in an inside an outer casing arranged inner housing or cage housed so that the shielding effect of the outer housing and the inner housing ses added.

The device according to the invention is particularly be prefers a combination with transverse and longitudinal Acceleration sensors as a small, compact device with CAN Bus interface (sensor cluster).

Additional embodiments and preferred embodiment forms of the invention will become apparent from the following description an embodiment with reference to the accompanying figures forth.

Show it

Fig. 1 is a schematic illustration of an arrangement of the type according to the invention,

Fig. 2A shows a schematic representation of the constructive concept Kon a practical embodiment,

Fig. 2B shows the isometric view of a practical embodiment according to Fig. 1 and Fig. 2A,

FIG. 2C, the alignment coordinates of the embodiment of FIGS. 2A and Fig. 2B to the vehicle.

In Fig. 1, the device-technical interaction of the components of an arrangement of the type according to the invention is shown in a schematic representation. The arrangement forms a device 1 for the simultaneous detection of yaw rate, longitudinal acceleration and lateral acceleration for ESP applications. The device has a housing 2 , in the interior of which all components are housed. There is a CAN bus connection 4 between the device and the electronic controller of the ESP system 3 . The CAN bus controller 5 is part of the device. The structure has two independent measuring channels 11 , 12 . These measuring channels are essentially similar sensory strands. The first measuring channel 11 consists of the yaw rate sensor YR1 with the associated signal conditioning circuit SC1 and the longitudinal acceleration sensor AX with the associated signal conditioning circuit SCX. The signals from these sensors are preprocessed in a first microcontroller MC1. For this there is a resident software PPSW 7 a and there is the possibility of receiving additional information via connection 6 a from the ECU via the CAN bus. The second measuring channel 12 consists of the yaw rate sensor YR2 with signal conditioning circuit SC2 and the lateral acceleration sensor AY with signal conditioning circuit SCY. The signals from these sensors are pre-processed in a second microcontroller MC2. For this purpose there is a resident software PPSW 7 b and it is possible to receive additional information via connection 6 b from the ECU via the CAN bus. The preprocessed signals are combined in a function level 8 . The redundancy checks described are carried out here and corresponding status signals are generated which signal the ECU whether entry into the control is temporarily permitted or whether one of the channels has suffered a total failure during the control. The preprocessed signals YR1, YR2, AX, AY and the status signals of the redundancy check are cyclically transmitted to the ECU via the CAN bus, so that it is possible to carry out a second independent redundancy check in the ECU.

Fig. 2A shows the constructive concept of the device 1 in a schematic representation. The torsionally rigid housing 2 is made of aluminum. It has two tabs 2 a, 2 b for attachment to the chassis and a CAN bus connector 9 . Inside there are two boards PCB1 and PCB2. YR1 and SC1 as well as YR2 and SC1 are arranged on PCB1. PCB1 is enclosed by a metallic shielding cage (Faraday cage) 10 , which prevents the penetration of powerful high-frequency radiation (e.g. from a mobile phone) into the sensitive yaw rate sensor system. On PCB2 all remaining components are housed, which have been described for Fig. 1 be.

The technology of the preferred yaw rate sensors ba based on micromechanical tuning forks made of quartz or mi Cromechanically generated structures made of silicon, which by the takes advantage of the Coriolis effect occurring during a rotation. in the According to the invention, both acceleration sensors also form  their signal processing stages together in the manner of a MEMS (Micro-Electronic-Mechanical-System) a complex unit. It is also within the spirit of the invention that a yaw rate each sensor and an accelerometer with their specific Signal processing stages like a MEMS a complex Form unity.

Before being used for example in ESP systems adds yaw rate sensors with a measuring range of +/- 75 ° / s up to +/- 100 ° / s.

The failure rate of the yaw rate sensors used is preferably at a maximum of about 70 FIT.

If two yaw rate sensors of the same type according to the invention, which is preferred, are used, the mechanical natural frequencies of the vibration elements can be selected, for example, as follows:

Sensor 1: f _o1 = 12.0 kHz, f _c1 = 12.2 kHz, Δf ₁ = 200 Hz
Sensor 2: f _o2 = 12.5 kHz, f _c2 = 12.6 kHz, Δf ₂ = 100 Hz

Elements are preferably used as acceleration sensors that sets a measuring range of approximately +/- 1.5 g to approximately +/- Have 2.0 g, where g is the acceleration due to gravity.

The acceleration sensors and yaw rate sensors used ren show in terms of signal resolution and noise behavior, based on a bandwidth of 50 Hz, preferably an Si Signal quantization from a minimum of about 10 bits.

Claims (12)

1. Arrangement for the detection of safety-critical measurement variables, in particular yaw rates and / or acceleration data in motor vehicles, comprising at least two independent measurement channels ( 11 , 12 ) with mutually independent sensors (YR1, YR2, AX, AY) and means for testing a Malfunction or failure of the measuring channels ( 5 , 8 ), characterized in that the first measuring channel ( 11 ) and the further measuring channel (s) ( 12 ) are operated in hot redundancy by using similar but not exactly the same sensors so that the Sensors are operating in parallel and without restrictions. 2. Arrangement according to claim 1, characterized in that the sensors a first yaw rate sensor (YR1), min at least one further yaw rate sensor (YR2) and possibly white other sensors such as acceleration sensors (AX, AY) grasp. 3. Arrangement according to claim 1 or 2, characterized net that with the sensors a sensor electronics (SC1, SCX, SCY, SC2) is connected, the output signals of electronic processing units (MC1, MC2, COMPARE) are evaluated and a connection to one Communication interface connection (CAN CONTROL) there is one with at least one central control (ESP / ECU) can be connected. 4. Arrangement according to at least one of claims 1 to 3,  characterized in that the electronic processing unit has a comparison unit (COMPARE), which the sensor signals of several yaw rate sensors and the changes over time of the signals compared. 5. Arrangement according to claims 2 to 4, characterized net that the yaw rate sensors mechanical vibration have elements and the yaw rate sensors in it distinguish that the resonance frequencies of the Schwin supply elements are so far apart that the vibrations do not affect each other and from Vibrations impressed on the outside of both yaw rate sensors not or only slightly stimulate. 6. Device consisting of a sealed housing ( 2 ) with a plug ( 9 ), wherein the arrangement according to at least one of claims 1 to 5 is comprised of the sealed housing. 7. The device according to claim 6, characterized in that the sensors are arranged in a within the housing ( 2 ) arranged shielding inner housing or cage ( 10 ). 8. The device according to claim 7, characterized in that the inner housing or the cage is not galvanically connected to the sealed housing is connected. 9. The device according to at least one of claims 6 to 8, characterized in that the yaw rate sensors on a first circuit board are arranged and at least  part of the electronic processing units (MC1, MC2, COMPARE) arranged on another circuit board is. 10. The device according to claim 9, characterized in that the first circuit board inside the shielding In nengehäuse or cage is arranged and the further PCB outside the shielding inner housing or cage is arranged. 11. The device according to at least one of claims 6 to 10, characterized in that the connector pins in the connector ( 9 ) are connected wirelessly to a circuit board. 12. The device according to device according to at least one of claims 6 to 11, characterized in that the sealed housing from support elements ( 2 a), preferably for different installation orientations, for installation in a motor vehicle.