Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
2000-03-10
2003-11-04
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C280S735000
Reexamination Certificate
active
06643574
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention lies in the automotive technology field. More specifically, the invention relates to a method and an apparatus for controlling the data transmission between two modules present in a motor vehicle, in particular between a control unit and an activation circuit of an occupant protection system.
The instantly described invention is based on the disclosure in European patent application EP 0 471 871 A1. There is described a method for controlling the data transmission between two modules present in a motor vehicle, in particular between a control unit and at least one firing unit of a motor vehicle occupant protection system. The modules are connected to one another via a communications interface and a communications bus. The first module defines the data to be transmitted in the form of code words in dependence on sensor signals generated by a first sensor and a second sensor, which is present as a redundant sensor. The known apparatus is designed as an occupant protection system with a central control unit and remote firing circuits. In the event of an impact (crash) detected by the sensors, the central control unit outputs firing commands, for example in the form of code words, to one or more firing circuits. The use of code words (by comparison with simply impressing a positive potential on the data line leading from the control unit to the relevant firing circuit) affords the advantage of preventing a possible unintended short circuit of the data line with the battery voltage from resulting in undesirable triggering of the occupant protection unit, for example the airbag or the seat belt pretensioner.
It is generally true in this context that increasingly, instead of parallel wiring, serial multiplex communications buses (for example usually CAN in motor vehicles, a squib bus for activation of the firing pellet, an Instabus, etc.) are being used for data exchange and for communication between the individual modules in the motor vehicle. For the data transmission, there is often a microcontroller present which compiles the data on the basis of the applied input variables, for example process parameters or sensor signals, and outputs them to other modules/units via the multiplex communications bus.
When a communications bus is used, it is usually driven via a hardware communications interface. The interface, by way of example, may be designed as a shift register and be controlled by a control device, in particular in the form of a microcontroller.
In this connection, particularly important and safety-critical input data are usually safeguarded by redundant sensors, resulting in sensor pairs comprising the actual sensor and associated safing sensor. In the case of occupant protection systems, in particular, in order to avoid erroneous triggering, there is provided in addition to the actual sensor, for example the acceleration sensor, a further, redundant sensor (safing sensor), for example in the form of a mechanical acceleration switch or of a further acceleration sensor, which responds only when a minimum value of the quantity to be detected, that is to say a minimum acceleration, occurs. The control unit controlling the generation of the activation signal, for example an airbag firing signal, generates the activation signal only when both sensors indicate an impact. The control unit thus performs an AND combination of the two sensor signals.
A problem that is generally posed in this connection is that of safeguarding the communication against errors. The data transmission itself can be safeguarded by means of corresponding protocol configuration, in particular by the addition of error detection codes, redundancy bits and the like, with the result that any errors that have occurred in the course of the data transmission can be detected at the receiver end and the transmitted code word is consequently rejected.
However, if the microcontroller itself erroneously generates the information packet that is to be transmitted and is protected by an error detection code, on account of internal malfunctions that may be caused by hardware defects or by software errors, these errors cannot generally be detected. Even when not only the actual sensor signal but also the signal of the additional redundant sensor is fed to the microcontroller, there is the risk that the microcontroller will generate an erroneous activation signal given an internal malfunction, that is to say there is the risk that an unnecessary firing signal will be put onto the bus even there is not a danger situation.
To afford improved protection against such malfunctions, consideration might be given to providing at least one further, redundant microcontroller and forwarding a firing signal only when all the microcontrollers generate the firing signal identically. However, that solution approach is very costly and, moreover, can only be implemented with difficulties in terms of the technology.
SUMMARY OF THE INVENTION
The object of the invention is to provide a method and a device for controlling the data transfer between two modules in a motor vehicle which overcomes the above-noted deficiencies and disadvantages of the prior art devices and methods of this kind, and which affords increased protection against the transmission of erroneous activation signals.
With the above and other objects in view there is provided, in accordance with the invention, a method of controlling data transmission between two modules in a motor vehicle, which comprises:
providing first and second modules connected to one another via a communications bus;
generating sensor signals with a first sensor and a second sensor, applying the sensor signals to the first module, and applying one of the sensor signals to a communications interface of the first module;
defining, with the first module, data to be transmitted in the form of code words in dependence on the sensor signals received from the first sensor and the second sensor;
evaluating the sensor signal applied to the communications interface of the first module for checking and/or changing a part of the code word applied to the communications interface for transmission via the communications bus.
In accordance with an added feature of the invention, the first module is a control unit and the second unit is one or more firing units of a motor vehicle occupant protection system.
In accordance with an additional feature of the invention, the sensor signal applied to the communications interface is a binary signal, and the method comprises comparing a value of the binary signal with an information section of the code word, the information section controlling an activation of the second module, and converting the information section or another part of the code word if the values in the communications interface deviate from one another.
In accordance with a further feature of the invention, the sensor signal applied to the communications interface is a binary signal, and the method comprises replacing an information section of the code word controlling an activation of the second module with the sensor signal.
In accordance with another feature of the invention, the sensor signal applied to the communications interface contains a single bit.
In accordance with a further feature of the invention, the code word contains an error detection code and the second module is equipped with an error detection function, and the method comprises not altering the error detection code even if an information section of the code word is changed.
In accordance with again a further feature of the invention, the occupant protection system (e.g., airbag system) is a system with a central control unit and remote firing circuits, and the defining step comprises forming a code word with an activation bit for controlling an activation of at least one of the firing circuits.
With the above and other objects in view there is also provided, in accordance with the invention, a data transmission control apparatus in a motor vehicle (e.g., a control unit and a fi
Anthofer Anton
Swart Marten
Cuchlinski Jr. William A.
Greenberg Laurence A.
Hernandez Olga
Locher Ralph E.
Siemens Aktiengesellschaft
LandOfFree
Method and apparatus for controlling data transmission... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for controlling data transmission..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for controlling data transmission... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3163970