Patent Application
20080122600
The present invention relates to a sensor, designed for placement in a series circuit, in particular for application in a motor vehicle, a method for operating such sensors and a device for operating them.
Different sensors for detecting impact events in motor vehicles have been used for years. Pressure sensors and acceleration sensors known as peripheral sensors are used for detecting side impacts outside of the associated electronic control unit of restraint systems. Acceleration sensors are used as additional peripheral sensors for detecting the impact or crash severity or are used for what is known as offset detection. Several similar sensors are often installed at different points in the motor vehicle serving the same purpose, such as PAS sensors in the A, B, and C columns of a motor vehicle body or pressure sensors in the front and rear doors of the vehicle for detecting side crashes. These sensors are connected to the associated control unit in a known manner for transmitting power and data, e.g., via bus systems for connecting multiple sensors to an interface.
German Patent Publication No. DE 101 14 504, which describes a method for transmission of data between a sensor and a control unit which are connected to one another via a dual-wire line, should be cited for illustration purposes. Both power for the sensor as well as data from the sensor are transmitted via this dual-wire line. This data also contains sensor-specific information such as details about its identification, status, and sensed values.
Present systems are typically relatively inflexible in their configuration and their architecture.
A restraint system is generally designed for one vehicle type and may only be modified or expanded to a limited extent. A bus system must normally also have a suitable configuration. Therefore, more and more peripheral sensors are used in airbag systems. In order to limit the number of terminals on the associated control unit, some automakers request bus systems. For reasons of regulations regarding electromagnetic compatibility (EMC), the data rates of such bus systems are limited. In a conventional design, this also results in a limitation of the data rate for each individual sensor. However, a high data rate is necessary in order to respond quickly enough to crash events, for example.
The sensor according to the present invention makes it possible to connect peripheral sensors in a series circuit to a single sensor interface of a control unit and to operate them according to the method according to the present invention.
This has the advantage that the full bandwidth of the physical sensor interface on the control unit may be used, and the data rate of each sensor may be increased vis-à-vis the related art.
The basic idea of the present invention is explained in the following.
The core of the present invention is a peripheral sensor which may be placed in a series circuit together with other sensors of the same design. This is also referred to by the term “cascadable” sensor. A point-to-point interface having the same hardware and software protocol is formed between the control unit and the first sensor and between the other sensors.
An essential advantage of the present invention is that, based on priority information, the respective sensor decides itself which signal it conveys, the signal from the preceding sensor or its own signal.
In this way, high data rates of the individual sensors may advantageously be used. The priority information of the respective signals may additionally be superimposed and thus modified during operation via a further priority criterion such as the signal height.
The sensor according to the present invention is designed for peripheral placement in a series circuit, in particular for application in a motor vehicle, and includes the following components:
It is thus achieved that an advantageously simple series circuit of peripheral sensors and their subsequent modification and variation are possible.
In a preferred embodiment, the analyzer unit has a selector device for selecting data received by the receiving interface or/and signals received from the sensor element for transmission to the transmitter interface. This is particularly advantageous since it makes simple differentiation of the signals possible.
It is particularly preferred that the selector device is designed for a selection decision from priority information of the data received via the receiving interface and predefinable data for transmission of the data received via the receiving interface or/and data of its own sensor element.
In addition, in a further embodiment, the selector device has a switching device for connecting the input connection or the sensor connection to the output connection and a control unit for controlling the switching device. The signal having the highest priority is thus immediately connected to the transmitting interface for transmission.
In a further embodiment, the selector device has a processing device for data reduction for data received via the receiving interface and for the signals of the sensor element, thereby advantageously expanding the range of use even for limited data rates.
In a further embodiment, the selector device has a memory device for the predefinable data or/and a control input for the selection decision for operating the switching device. The predefinable data may thereby be variably called, i.e., also depending on the operating condition, this also being possible via a control input.
In a further embodiment, the selector device has a further memory device for storing collected received data making temporary storage of certain data quantities possible which are only transmitted after the transmission of data having the highest priority.
A method according to the present invention for operating sensors situated in a series circuit on a control unit, in particular in a motor vehicle, is characterized in that data of a signal of a sensor element is analyzed and priority information is appended to the data according to predefinable data values in each sensor of the series circuit, that data of a sensor connected via a receiving interface is received and priority information of the received data and the data of the sensor element is compared with each other or with predefinable data values in each sensor within the series circuit with the exception of the sensor whose receiving interface has no connection, data being transmitted to a transmitting interface of a sensor connected to the transmitting interface or to a sensor interface of a control unit in the sequence of the priorities, all interfaces being operated with the same hardware and software protocol. It is thereby advantageously ensured that high data rates may also be used, the data having the highest priority being always transmitted.
In a further embodiment, a predefinable data value or a signal height is the priority information. During operation, a signal height may advantageously adapt or modify the predefined priority information according to the instantaneous operating condition, thereby achieving advantageous flexibility.
In a further embodiment, the predefinable data value is modifiable via a control input, thereby making external influencing possible in a simple manner.
It is advantageous for high data rates that, in each case, the data of the sensors is collected in a memory device and subsequently transmitted.
In the case of limited data rates, the data of the sensors is subjected to a data reduction algorithm, whereby an advantageous compression of the data takes place for rapid data transmission.
It is advantageous that in one embodiment transmission of the data and communication of the sensors among each other and with the control unit are executed synchronously or partly asynchronously, in the case of partly asynchronous execution, the last sensor (5) in the series circuit determining the clock rate.
A device according to the present invention having a control unit and a series circuit of sensors is characterized in that a first sensor having a transmitting interface is connected to a sensor interface of a control unit via a first connection, a receiving interface of the first sensor being connected to the transmitting interface of a second sensor via a second connection, and that, via third and fourth connections, additional sensors are connected in series among each other in such a way that the receiving interface of the respective preceding sensor is connected to the transmitting interface of the respective downstream sensor. In this way, an advantageously simple device of a series circuit of cascadable sensors to a single sensor interface of a control unit is made possible.
Advantageous embodiments and refinements of the present invention arise from the subclaims and the description with reference to the drawing.
The present invention is explained in greater detail in the following based on the exemplary embodiment shown in the figures of the drawing.
A first sensor 2 with a sensor interface 18 is initially connected to control unit 1 via a first connection 6. Additional sensors 3, 4, 5, follow in a series circuit: A second sensor 3 is connected to the preceding first sensor 2 via a second connection 7 and to a subsequent third sensor 4 via a third connection 8. In this exemplary embodiment, the series circuit is composed of four sensors 2 through 5, the fourth sensor 5 being connected to the preceding third sensor 4 via a fourth connection 9.
This arrangement of sensors 2 through 5, also referred to as “cascadable,” has connections between certain interfaces of sensors 2 through 5 and control unit 1, which form point-to-point interfaces and are all operated via the same hardware and software protocol. Sensors 2 through 5 are interconnected via internal interfaces which are described with reference to
Sensor element 10 detects a certain variable, such as pressure or acceleration, and converts it into an electrical sensor signal which is conveyed to analyzer unit 11 via a sensor connection 15. Analyzer unit 11, a special integrated circuit, for example, analyzes the signal of sensor element 10 and, via an input connection 14, receives data from receiving interface 12 of subsequent sensor 3 through 5 connected thereto.
Analyzer unit 11 conveys either the signal received from receiving interface 12 or the signal of sensor element 10 to transmitting interface 13 via an output connection 16 according to a certain selection criterion, either a preceding sensor 2 through 4 or sensor interface 18 of control unit 1 being connected to transmitting interface 13.
A signal is selected in selection device 17 of analyzer unit 11 as a signal to be conveyed, having the highest priority, in this example via priority information. Analyzer unit 11 of subsequent sensor 3 through 5 appends to the data of the respective sensor element 10 priority information which is present as a fixed predefined value in a memory device (see
In a further embodiment, the signal height of a sensor signal may also be the priority criterion. If in normal driving operation, for example, only the data of second sensor 3 is transmitted and a crash event suddenly occurs which third sensor 4 detects, then its signal height is substantially greater than that of second sensor 3. Consequently, the signal of third sensor 4, arriving in second sensor 3, is recognized as highest priority due to its signal height and is immediately transmitted.
Unidirectional transmission in the series circuit according to
The present invention is not limited to the above-described exemplary embodiments, but rather it is modifiable in many different ways.
So it is conceivable, for example, that in the case of a limited data rate, data reduction algorithms are used in the respective analyzer unit 11 of a sensor 2 through 5.
Furthermore, it is also conceivable that selection device 17 has a control input 19 on its control unit 20 via which external control signals for priority specification or priority change may be input depending on and in accordance with the operating conditions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2004 051 275.2 | Oct 2004 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP05/53805 | 8/3/2005 | WO | 00 | 10/29/2007 |
