Electronic device

• US 5,357,141 A
• Filed: 01/13/1993
• Issued: 10/18/1994
• Est. Priority Date: 04/02/1988
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Nitschke, Werner, Taufer, Peter, Pfeufer, Reinhard, Drobny, Wolfgang
• Primary Examiner(s): Pellinen, A. D.
• Assistant Examiner(s): Fleming, Fritz M.
• Application Number:
  US08/005,852
• Time in Patent Office: 643 Days
• Field of Search: 307/9.1, 307/10.1, 340/436-438, 340/669, 340/825.34, 340/825.07, 340/825.08, 340/825.57, 340/825,62, 180/274, 180/281, 180/282, 180/286, 280/735, 364/424.05
• US Class Current: 307/10.1
• CPC Class Codes: B60R 16/0315 using multiplexing techniques multiplexing for transmission of signals G08C15/00; multiplexing for electrical communication in general H04J
• CPC Class Codes: B60R 2021/01068 between different sensors and airbag control unit
• CPC Class Codes: B60R 2021/01095 optical
• CPC Class Codes: B60R 2021/01115 specific data frames
• CPC Class Codes: B60R 21/01 Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents electrical circuits for transmission of signals between steering wheel and the vehicle itself B60R16/027; for electrically actuating belt retractor locking means B60R22/343

Abstract

An apparatus for controlling motor vehicle safety devices has a plurality of sensors, each coupled to a control unit. The control unit in turn activates inertial restraining devices based on the output signals generated by the sensors.

Claims

1. A device for controlling motor vehicle safety devices comprising:

a plurality of sensors mounted on the motor vehicle and adapted to transmit output signals indicative of an acceleration of the motor vehicle;

a control unit coupled to the sensors and to the safety devices, the control unit evaluating the signals transmitted by at least one of the sensors and controlling actuation of the safety devices as a function of the evaluated signals;

a serial data transmission line coupling each of the sensors to each of the other sensors and to the control unit;

the serial data transmission line providing bidirectional communication of signals among the sensors, and between each of the sensors and the control unit;

each of the sensors receiving all of the signals transmitted over the serial data transmission line by each of the other sensors and by the control unit;

each of the sensors processing the signals received from each of the other sensors;

each of the sensors processing the signals received from the control unit; and

each of the sensors determining when to transmit a respective signal over the serial data transmission line as a function of the signals received and processed from each of the other sensors and of the signals received and processed from the control unit.

2. The device according to claim 1, wherein at least one sensor is mounted within the control unit or in its immediate proximity.

3. A device as defined in claim 1, further comprising:

a plurality of evaluation circuits, each evaluation circuit being coupled between a respective sensor and the serial data transmission line and adapted to convert the output signal of the respective sensor into a signal sequence for transmission over the data transmission line.

4. A device as defined in claim 3, further comprising:

a plurality of interface circuits, each interface circuit being coupled between a respective evaluation circuit and the data transmission line and adapted to convert analog signals generated by the respective sensor into digital signals for transmission over the data transmission line.

5. A device as defined in claim 4, wherein

the data transmission line is an optical fiber line, and each interface circuit is adapted to convert the electronic signals generated by the respective sensor into optical signals for transmission over the data transmission line and, in turn, to convert the optical signals transmitted by the control unit to the respective sensor over the data transmission line into electronic signals.

6. A device as defined in claim 3, wherein each evaluation circuit is adapted to transmit signals to the control unit indicative of the type of the respective sensor and its mounting location on the motor vehicle.

7. A device as defined in claim 6, further comprising means for storing the signals generated by the evaluation circuits indicative of the type of each respective sensor and its mounting location on the motor vehicle.

8. The device according to claim 7, wherein the control unit, in order to identify each respective sensor, compares the data indicative of the type and mounting location of each respective sensor stored in the means for storing and transmitted by the evaluation circuits.

9. A device as defined in claim 1, wherein the control unit detects an inoperable sensor, whereupon the detection of an inoperable sensor, the control unit is adapted to apply a weighted factor to the output signal transmitted by each operable sensor to compensate for the inoperable sensor.

10. A method for controlling motor vehicle safety devices as a function of output signals indicative of an acceleration of the motor vehicle transmitted by a plurality of sensors mounted on the motor vehicle, wherein each of the sensors is coupled to each of the other sensors and to a control unit through a serial data transmission line providing bidirectional communication of signals among the sensors, and between each of the sensors and the control unit, and wherein the control unit controls actuation of the safety devices as a function of the signals transmitted by the sensors, the method comprising the following steps:

detecting the number of operable sensors and the type of each operable sensor through the serial data transmission line;

assigning an ordinal number to each operable sensor, thus forming a ranking sequence for the sensors, wherein the ranking sequence determines the order in which the control unit communicates with each of the sensors through the serial data transmission line;

transmitting all of the signals from each of the sensors and from the control unit over the serial data transmission line;

receiving, in each of the sensors, all of the signals transmitted from each of the other sensors;

receiving, in each of the sensors, all of the signals transmitted from the control unit;

processing, in each of the sensors, the signals transmitted from each of the other sensors;

processing, in each of the sensors, the signals transmitted from the control unit; and

determining when to transmit a respective signal from each of the sensors over the serial data transmission line as a function of the signals received and processed from each of the other sensors and of the signals received and processed from the control unit.

11. A method as defined in claim 10, further comprising the step of, prior to forming a ranking sequence, transmitting a reset pulse from the control unit over the data transmission line, the reset pulse having a duration longer than the pulses transmitted during normal operation, and wherein the assigning step includes the step of transmitting a characteristic code word for each operable sensor to the control unit over the data transmission line.

12. A method as defined in claim 11, wherein the assigning step further includes the following steps:

upon transmission of the complete coded word for a first operable sensor to the control unit, assigning to the first operable sensor an ordinal number characteristic of the highest priority level, and then commencing bidirectional communication between the first operable sensor and the control unit.

13. A method as defined in claim 12, wherein the assigning step further includes the following steps:

upon completing the bidirectional exchange of data between the first operable sensor and the control unit, successively identifying each additional operable sensor and performing bidirectional communication between each additional operable sensor and the control unit until each operable sensor is assigned an ordinal number, thus forming the ranking sequence.

14. A method as defined in claim 10, wherein the assigning step includes the following steps:

transmitting a command signal by the control unit onto the data transmission line;

transmitting a code word in the form of a bit string for each operable sensor onto the data transmission line in response to the command signal;

comparing each bit transmitted for each operable sensor to the status of the data transmission line, and if the bit transmitted by an operable sensor does not match the status of the data transmission line, ceasing the transmission of the code word for the operable sensor until the control unit transmits another control signal.

15. A method as defined in claim 14, wherein the assigning step further includes the following steps:

upon the transmission of the command signal by the control unit, measuring a characteristic time delay for each sensor, and upon expiration of the characteristic time delay for each sensor, determining whether the code word for another sensor is present on the data transmission line, and if the code word for another sensor is not present on the data transmission line, transmitting the code word for the sensor on the data transmission line.

16. A method as defined in claim 12, wherein the assigning step further includes the following steps:

transmitting a command signal from the control unit onto the data transmission line;

defining the operable sensor with the ordinal number characteristic of the highest priority level as a master operable sensor, and transmitting a code word in the form of a bit string onto the data transmission line for the master sensor after a first time delay following the command signal; and

upon completion of the transmission of the code word for the master sensor, successively transmitting the code words for each other operable sensor upon the expiration of a characteristic time delay for each operable sensor following the command signal, wherein each characteristic time delay is selected so that the transmission of a code word is initiated after the transmission of a preceding code word is completed.

17. A method as defined in claim 14, wherein the assigning step further includes the following steps:

upon completing the transmission of a complete code word for a sensor, reading the complete code word transmitted over the data transmission line and comparing the complete code word with the code word intended to be transmitted over the data transmission line, and upon the expiration of a time delay, if the complete code word is the same as the code word intended to be transmitted, and if the code word for another sensor is not present on the data transmission line, transmitting the code word for another sensor.

18. A method as defined in claim 10, wherein the assigning step includes the following steps:

transmitting a plurality of command signals from the control unit onto the data transmission line, wherein each command signal is directed to a respective operable sensor and designates a different point in time for the respective operable sensor;

transmitting a code word in the form of a bit string for each operable sensor onto the data transmission line, each code word being transmitted at a separate point in time with respect to the other code words based on the command signal for the respective operable sensor; and

comparing each bit transmitted for each operable sensor to the status of the data transmission line, and if the bit transmitted by a sensor does not match the status of the data transmission line, ceasing the transmission of the code word for the sensor until the control unit transmits another command signal.

19. A method as defined in claim 10, further comprising, after the assigning step, a step selected from the group including:

a) determining the mean value of the acceleration signals generated by each operable sensor over a predetermined period of time, and controlling the release of the safety devices based thereon;

b) integrating the acceleration signals generated by each operable sensor and controlling the release of the safety devices based thereon; and

c) determining the maximum value of the acceleration signals generated by each operable sensor over a predetermined period of time, and controlling the release of the safety devices based thereon.

20. A method as defined in claim 10, wherein the assigning step includes the step of transmitting to the control unit data selected from the group including:

data indicative of the supply voltage for each operable sensor; and

data indicative of the mounting location of each operable sensor.

21. A method as defined in claim 10, further comprising the step of upon detecting an inoperable sensor, applying a weighted factor to the output signal transmitted by each operable sensor to compensate for the inoperable sensor.

22. A method as defined in claim 10, further comprising, after the assigning step, the step of converting the signals generated by the sensors into digital signals for transmission as bit strings over the data transmission line.