Method for adapting sensor cells of a seat mat to a mechanical prestress

State of the art

p0001The invention is based on a method for adapting sensor cells of a seat mat to a mechanical prestress according to the genus of the independent patent claim.

p0002It has already been disclosed in the Offenlegungsschrift -A-<patcit id="pcit0001" dnum="WO9710115A"><text>WO 97/10115</text></patcit> It is known to adapt each sensor cell of a seat mat to a mechanical pretension caused by the shoring-up of the seat mat in a vehicle seat. Such a seat mat is used to determine whether a person is on the vehicle seat and what sitting position that person has taken, and also, if necessary, to determine how difficult the person is. These data are then used to drive an airbag.

p0003From the unpublished <patcit id="pcit0002" dnum="WO0185497A"><text>WO-A-01/85 497</text></patcit> It is known that a calibration unit is present by means of which sensor bias voltages of a sensor mat are normalized in a calibration process. These data are then transmitted in a memory of a control device.

Advantages of the invention

p0004The method according to the invention for adapting sensor cells of a seat mat to a mechanical pretension having the features of the independent patent claim, on the other hand, has the advantage that the bias voltage is determined by a diagnostic tester on the manufacturer side and correction data are derived therefrom with which the control device is configured, The measuring values ​​can be corrected during operation. Thus, seat mats can still be used even in the case of different installation conditions, provided that the mechanical pretension is within given parameters and the sensor cells can still measure a bearing pressure by a seated person.

p0005Advantageous improvements of the method according to the independent patent claim for the adaptation of sensor cells of a seat mat to a mechanical prestressing are possible by means of the measures and developments described in the dependent claims.

p0006It is particularly advantageous that the correction values ​​are stored in a memory of the control device so that the correction values ​​are permanently available during the operating time of the control device in this memory which was initially initialized with zero values. If necessary, this memory can also be overwritten with new correction values ​​even in the case of a new installation of a seat mat.

p0007In addition, it is advantageous that, when the diagnostic tester is connected to the control device, a password is first interrogated by the diagnostic test so that only a secure access to the control device and the writing of the memory of the control device is possible.

p0008Furthermore, it is advantageous that a diagnostic test is available for carrying out the method, which has a data transmission interface for connection to the control device, a separate memory for the setpoints, which here can be a permanent memory, and a processor for carrying out the comparison between the setpoints and The sensor values.

p0009It is also advantageous that a control device is provided for carrying out the method according to the invention which has its own data transmission interface for connection to the diagnostic test and a further data transmission interface for connection to the seat mat as well as a processor eg a microcontroller for evaluating the sensor values ​​and a memory for Recording the correction values.

drawing

p0010Exemplary embodiments of the invention are illustrated in the drawing and are explained in more detail in the following description. Show it:<ul><li><figref idrefs="f0001">FIG</figref> A block circuit diagram of the diagnostic tester and control device according to the invention, and FIG</li><li><figref idrefs="f0001">FIG</figref> 3 is a flowchart of the method according to the invention.</li></ul>

description

p0011Recognition of persons in the vehicle is an increasingly important task for restraint systems. It is particularly important to determine for which person an air bag can be used and for which it is not. In the case of adaptively adjustable airbags, it is also possible to trigger this airbag in the event of an impact and a resulting triggering situation as a function of the weight of the person. This is to ensure that an optimum restraining force is exerted on the person to be protected. In addition to optical and ultrasonic sensors, weight sensors are also used, in particular a seat mat with sensor elements, each sensor element being designed as a pressure-sensitive resistor. These sensor elements are arranged in a matrix, which are cyclically interrogated by a control device used for this seat mat. The individual sensor elements have a lower resistance, the higher the applied pressure on them. The sensor elements can also be used to create seat profiles, which provide information on how the person in question is sitting. Through the installation of a seat mat into a vehicle seat, different mechanical pre-stresses are exerted on the individual sensor elements due to the different circumstances of the vehicle seat.

p0012According to the invention, a diagnostic test is then carried out on the manufacturer side, which sensor values ​​have the sensor values ​​of the individual sensor elements without a load on the seat surface in order to derive correction values ​​which provide compensation for such mechanical biases due to the installation and then used as correction values ​​during operation.

p0013In <figref idrefs="f0001">FIG</figref> The configuration in which a diagnostic test is connected to a control device, which is connected to a seat mat, is shown as a block diagram. A diagnostic tester 1 is connected via a data input / output to a control device 2 for a seat mat. A seat mat 3 with various sensor elements, which are shown here as circles, is connected to a data input of the control device 2. The control device 2 is connected to other vehicle components such as a restraint system via a bus, for example, via a bus, in order to transmit the seat mat data, ie the sensor values, to these vehicle components in raw and / or evaluated form.

p0014<figref idrefs="f0002">FIG</figref> Shows as a block diagram the internal structure of the diagnostic tester 1 and the control device 2. The diagnostic tester 1 has a data transmission interface 10 via which the diagnostic tester 1 is connected to the control device 2. Via a data input / output, the data transmission interface 10 is connected to a processor 11 of the diagnostic tester 1. The processor 11 is connected to a memory 12 via a second data input / output. The setpoints and the password are stored in the memory 12. The processor 11 is used to compare the setpoints with the sensor values ​​and to evaluate the password query.

p0015The data transmission interface 10 is used to carry out the data transmission between the diagnostic analyzer 1 and the control device 2. The control device 2 has a first data transmission interface 13, a further data transmission interface 16, a memory 15 and a processor 14, which is here a microcontroller. The data transmission interface 13 is connected to the data transmission interface 10 of the diagnostic tester 1 via a first data input / output. The data transmission interface 13 is connected to the processor 14 via a second data input / output. The processor 14 is connected to the memory 15 via a second data input / output. At a third data input / output, the processor 14 is connected to the data transfer interface 16. The data transmission interface 16, via its second data input / output, connects the control device 2 to the sensor mat 3. The memory 15 serves to store the passwords and the correction values ​​for the sensor values. The processor 14 performs the correction of the sensor values ​​before they are further processed. The data interfaces 13 and 16 are used for data transmission with the diagnostic tester 1 and the sensor mat 3.

p0016In <figref idrefs="f0001">FIG</figref> The method according to the invention is shown as a flow chart. In method step 4, the diagnostic test device 1 is connected to the control device 2 by means of the connection via the data transmission interfaces 10 and 13. After the initialization of the data transmission connection between the diagnostic test device 1 and the control device 2, the control device 2 asks from the diagnostic test device 1 a password, And terminate the procedure if the password of the diagnostic test is not correct.

p0017If, however, the password is correct, the readout of the sensor values ​​of the sensor mat 3 by the diagnostic test 1 is carried out in method step 6. In process step 7, processor 11 now performs a comparison of the sensor values ​​with setpoints, which processor 11 loads from memory 12. The difference between the desired values ​​and the sensor values ​​then transfers the diagnostic test 1 to the control unit 2 as the correction values. The processor 14 stores these correction values ​​in the memory 15 in method step 9. During the operation of the sensor mat 3, the processor 14 then corrects the read-out sensor values ​​from the sensor mat 3 and the correction values ​​in the memory 15. The correction values ​​are thus used for calibrating the sensor values. The method is used with an unloaded seat surface, so that only mechanical stresses, which are caused by the installation of the sensor mat 3, influence the sensor cells.