Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle diagnosis or maintenance indication
Reexamination Certificate
1999-11-17
2001-11-20
Chin, Gary (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle diagnosis or maintenance indication
C701S033000, C701S048000, C340S870030
Reexamination Certificate
active
06321150
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an abnormality monitoring device for a vehicle control system formed by interconnecting a plurality of control units of which objects to be controlled are different from one another by multiplex communication lines.
2. Description of the Related Art
In a vehicle control system employed in various vehicles, including motor vehicles, various controls of an engine, a transmission, suspensions, an air conditioner and the like are respectively assigned to a plurality of electronic control units (ECUs) including microcomputers and others, which are mounted on the vehicle. The ECUs are interconnected by communication lines, and control data transmission is performed among the ECUs, to thereby improve its total control performance.
In such a vehicle control system, it is important that each ECU carries out a self-diagnosis for its peripheral system, and additionally that the vehicle control system performs the monitoring operation to detect an abnormality in the overall control system. Conventionally, each of those ECUs mutually monitors an abnormality or abnormalities of the remaining ECUs by use of watchdog timers or by echo backing communication data.
Recently, in the vehicle, the amount of data transmitted between those ECUs increases. The data amount increase creates many problems, such as wire harness increase in size, wire layout restriction, and vehicle weight increase. To cope with those problems, there is a trend of adopting the multiplex communication technique for the communications among the ECUs. However, addition of the hardware for monitoring the abnormality, such as watchdog timer wires goes against the trend, and further increases the system cost.
The abnormality monitoring by the data echo-backing has also problems. It takes a long processing time. A traffic of the transmission path increases. As a result, the throughput of the overall system reduces.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an abnormality monitoring device for a vehicle control system in which when an abnormality occurs in one control unit, another control unit accurately detects the abnormality without any additional hardware specially designed for abnormality monitoring and any additional complex process.
To achieve the above object, the present invention provides a first abnormality monitoring device for a vehicle control system formed by interconnecting a plurality of control units of which objects to be controlled are different from one another by multiplex communication lines, the improvement being characterized in that one specific control unit in the vehicle control system includes means for inserting a count value indicative of the number of sending times, which is independent of control data, into communication data, and for sending the resultant communication data, and a single other control unit of the vehicle control system includes judging means which monitors the count value of the communication data transmitted from the specific control unit, and decides that the specific control unit is abnormal, when the count value is not consecutively updated.
The invention also provides a second abnormality monitoring device for a vehicle control system formed by interconnecting a plurality of control units of which objects to be controlled are different from one another by multiplex communication lines, the improvement being characterized in that a first control unit in the vehicle control system includes means for inserting a count value indicative of the number of sending times, which is independent of control data, into communication data, and for sending the resultant communication data to a second control unit in the vehicle control system, and a third control unit of the vehicle control system includes judging means which monitors the count value of the communication data transmitted from the first control unit to the second control unit, and decides that the first control is abnormal, when the count value is not consecutively updated.
In the first abnormality monitoring device, when the specific control unit in the vehicle control system sends data, it inserts a count value indicative of the number of sending times, which is independent of control data, into the data, and then sends the resultant data. Another control unit monitors the count value. When the count value is not consecutively updated, it is judged that the specific control unit is abnormal.
In the second abnormality monitoring device, when data is sent from the first control unit to the second control unit, it inserts a count value indicative of the number of sending times, which is independent of control data, into the data, and sends the resultant data to the second control unit. The third control unit monitors the count value. When the count value is not consecutively updated, it is judged that the first control unit is abnormal.
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Chin Gary
Farber Martin A.
Fuji Jukogyo Kabushiki Kaisha
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