DE102019203211A1 - Sensor device, method and computer program product for the sensor-based position determination of a component for a vehicle - Google Patents

Abstract

Sensor device (10) for determining the position of a component for a vehicle, comprising a light source (12) for generating a light signal (121), a transmitter element (14) which has a reflective surface (141) for reflecting the generated light signal (121), wherein on the reflective surface (141) has a coding structure (142) incorporated with a bit sequence, a light sensor (16) for detecting the reflected light signal (161) in order to generate a pixel value distribution (162), and an evaluation unit (18) for decoding the coding structure ( 142) based on the pixel value distribution (162) in order to determine the bit sequence.

Description

TECHNICAL AREA

The present invention relates to the field of sensor-based position determination of a component for a vehicle. In particular, the present invention relates to a sensor device, a method and a computer program product for this purpose.

TECHNICAL BACKGROUND

In the modern automotive industry, a large number of vehicle manufacturing processes are automated. It is essential that the various components of a vehicle (e.g. shift rod, actuator shaft) are assembled together in a coordinated manner. To make this possible, sensor devices are used to precisely determine the position of components for vehicles. In particular, the movement of the vehicle parts relative to one another is important for various functions.

In many mechatronic systems, the task is to determine the position of a component. For example, inductive and magnetic methods are known from the prior art. The known magnetic methods are mainly based on the Hall effect or on a magnetoresistance effect (AMR, GMR, TMR).

However, these two types of methods have the disadvantage that they are relatively sensitive to changes in the air gap and generally require linearization of the measured variable. The development of electromobility has resulted in ever greater currents in vehicles. This means that the requirements for immunity to stray fields are becoming ever higher.

In the case of sensors based on magnetic fields, it is therefore necessary either to carry out shielding measures or to carry out a differential position measurement. However, each of these solutions has certain disadvantages. Inductive sensors are insensitive to static or low-frequency magnetic fields due to their operating principle, but can also be severely impaired by conductive materials in the area of the sensor environment.

The invention is therefore based on the object of enabling a sensor device with higher linearity that is at the same time insensitive to low-frequency electromagnetic influences.

This object is achieved by a sensor device, a method and a computer program product according to the independent claims.

The sensor device is based on reflection or transmission optics. The sensor device is suitable for determining the position of vehicle components, for example a shift rod or an actuator shaft.

The light source is any light source that is suitable for emitting a light signal in the form of a light beam. The light signal can be in the visible optical spectrum. Alternatively, the light signal can be at least partially in the ultraviolet or infrared spectrum. The light signal can comprise a pulsed, in particular a pulse-modulated light signal.

The transmitter element is any element that is suitable for applying a reflection or transmission surface to it and thus generating the image of a bit pattern. For example, the transmitter element can be a separate element from the vehicle component whose position is to be determined. Alternatively, it can be at least partially a part of the vehicle component. The reflection or transmission surface preferably has an at least average reflective material. Furthermore, the reflection efficiency of the reflection / transmission surface can be selected as a function of the wavelength of the light signal generated.

The coding structure is a physical structure that is incorporated into the reflection / transmission surface in such a way that a bit sequence is “stored” on the reflection / transmission surface. It can be a stripe pattern with several stripes that differ in their widths, lengths, gradients, colors, contrast values, heights, depths, material compositions ... etc.

The light sensor is any sensor that is suitable for detecting the light signal after reflection on the reflection / transmission surface of the transmitter element. For example, it can be a charge-coupled device camera (CCD camera) or a complementary metal-oxide-semiconductor camera (CMOS camera) or another image sensor.

The light sensor preferably comprises an array of sensor elements, each of which corresponds to an image point (eg pixel or voxel) of the sensor image produced. By detecting the reflected light signal, at least some of the sensor elements of the array are activated. In the Sensor data contained in individual pixels are values of one or more pixel parameters. The pixel parameters can include one or more of intensity, brightness, contrast value, ... etc.

The evaluation unit can have a graphic processing unit (GPU) which is able to determine the pixel value distribution (e.g. pixel value distribution or voxel value distribution) from the values of the pixel parameters for the respective pixels. The evaluation method of the evaluation unit can, for example, be based on a predefined assignment of bit values (for example “1” and “0” in dualism) to the pixel parameter (primary pixel parameter) or to a secondary parameter of the respective pixels derived from the pixel parameter. This predefined assignment can be stored in the sensor device or can be called up from an external storage medium (such as a server or cloud system). In this way, the bit sequence results from the distribution of pixel values.

The optical measuring principle according to the invention for determining the position is distinguished by its high linearity. Furthermore, the measuring method is more robust than inductive and magnetic methods against influences such as stray fields and static or low-frequency magnetic fields. The position determination is therefore more precise and more reliable.

Advantageous refinements and developments are specified in the subclaims.

According to one embodiment, the light source and the light sensor are arranged on the same side of the reflective surface of the transmitter element.

This advantageously enables a compact sensor structure, which also has a cost-reducing effect on the production of the sensor device.

According to a further embodiment, the coding structure comprises a plurality of strips, one bit being assigned to each of the plurality of strips.

This advantageously enables a coding of the transmitter element that is easy to implement and therefore also inexpensive.

According to a further embodiment, the plurality of strips have a first width and a second width, the second width being greater than the first width.

The two different stripe widths are each assigned to a bit value (such as “1” or “0”). The coding structure can therefore be implemented without great design and manufacturing effort.

According to a further embodiment, the evaluation unit is designed to identify a rising edge and a falling edge in the pixel value distribution, preferably an intensity distribution, for each of the multiple stripes in order to determine a distance between the rising and falling edges.

In this case the intensity is the primary pixel parameter and the distance between the rising edge and the falling edge is the secondary pixel parameter. The distance can be determined based on half the height of the intensity maximum of the respective stripe. In this way, the position determination is particularly accurate.

According to a further embodiment, the coding structure comprises a Gray code.

In this way, incorrectly determined bits can be recognized and corrected. The Gray code preferably has a Hamming distance of at least 3. An example of the Gray code is (7, 4). This means that 7 bits (namely 4 data bits and 3 parity bits) are required. This requires a narrower stripe pattern.

According to a further embodiment, the light source is designed to emit a frequency-modulated light signal.

The influence of stray light when evaluating the light signal (e.g. using a lock-in amplifier) is greatly reduced. This also enables redundant measurements, which makes the result of the position determination even more precise and reliable. As an alternative or in addition, the use of a second light source is conceivable in order to increase the availability of the sensor device by enabling redundant measurements.

According to a further embodiment, the evaluation unit is designed to determine position data of the encoder element from the determined bit sequences based on a conversion table.

The position data of the transmitter element relate to a coordinate system, for example the coordinate system of the transmitter element, the vehicle component, the vehicle or an external coordinate system outside the transmitter element or outside the vehicle component. A position of the encoder element with regard to the coordinate system is assigned to each bit sequence. To this Way, the position determination is possible with manageable effort.

The computer program product according to the invention for detecting the surroundings of a vehicle is designed to be loaded into a memory of a computer and comprises software code sections with which the method steps of the method according to the invention are carried out when the computer program product is running on the computer.

A program belongs to the software of a data processing system, for example an evaluation device or a computer. Software is a collective term for programs and associated data. The complement to software is hardware. Hardware describes the mechanical and electronic alignment of a data processing system. A computer is an evaluation device.

Computer program products generally comprise a sequence of instructions which, when the program is loaded, cause the hardware to carry out a specific method that leads to a specific result. When the program in question is used on a computer, the computer program product produces the aforementioned technical effect.

The computer program product according to the invention is platform independent. That means it can run on any computing platform.

The software code sections are written in any programming language, for example Python.

• 1 eine schematische Darstellung einer Sensoreinrichtung gemäß einer Ausgestaltung;
• 2 eine weitere schematische Darstellung der Sensoreinrichtung aus 1;
• 3 eine schematische Darstellung einer Kodierungsstruktur eines Geberelements der Sensoreinrichtung aus 1;
• 4 ein Diagramm einer von der Sensoreinrichtung erfassten Pixelwerteverteilung;
• 5 ein Diagramm für von der Sensoreinrichtung ermittelten Positionsdaten; und
• 6 ein weiteres Diagramm für von der Sensoreinrichtung ermittelten Positionsdaten.

Embodiments will now be described by way of example and with reference to the accompanying drawings. Show it:

• 1 a schematic representation of a sensor device according to an embodiment;
• 2 a further schematic representation of the sensor device 1 ;
• 3 a schematic representation of a coding structure of a transmitter element of the sensor device 1 ;
• 4th a diagram of a pixel value distribution detected by the sensor device;
• 5 a diagram for position data determined by the sensor device; and
• 6th a further diagram for position data determined by the sensor device.

In the figures, the same reference symbols relate to the same or functionally similar reference parts. The relevant reference parts are identified in the individual figures.

1 shows a schematic representation of a sensor device 10 according to one embodiment. The sensor device 10 includes a light source 12 for generating a light signal 121 , a donor element 14th that has a reflective surface 141 (please refer 2 ) to reflect the generated light signal 121 having. On the reflection surface 141 is a coding structure 142 incorporated with a bit sequence. The coding structure 142 is designed as a stripe pattern with several stripes that differ in their widths and brightnesses.

The sensor device 10 further comprises a light sensor 16 for detecting the reflected light signal 161 (please refer 2 ) to obtain a pixel value distribution 162 (please refer 4th ) and an evaluation unit 18th which is not shown here and for decoding the coding structure 142 based on the pixel value distribution 162 is used to determine the bit sequence. In 2 is the sensor device 10 out 1 shown in a schematic side view.

As in 3 Shown by way of example and enlarged, the striped pattern comprises two different widths. The light streaks 143a, b with the larger width correspond to the bit value "1", while the light stripes 143c with the smaller width correspond to the bit value "0". This corresponds to in 3 Example striped pattern of the bit sequence "1-1-0".

4th Figure 11 shows a diagram of one of the sensor means 10 recorded pixel value distribution 162 obtained from the reflection data of the stripe pattern 142 out 3 results. The diagram shows three maxima, each with a rising edge 163a, b, c and a falling edge 164a, b, c exhibit. A width W _a , W _b , W _c (approximately halfway up the maximum) can be determined between each pair of flanks of the respective maximum. The two maxima on the left in the drawing view have a greater width than the maximum on the right in the drawing view. The evaluation unit thus recognizes 18th that the two maxima on the left are the bit value “1” and the right maximum is the bit value “0”. The evaluation unit derives from this 18th the bit sequence "1-1-0". The evaluation unit can use the bit sequence 18th the position of the encoder element using a look-up table (LUT) 14th determine.

5-6 each show a diagram for of the sensor device 10 determined position data. When measuring in 6th is compared to the measurement in 5 an air gap of 4 mm is included in the measurement setup. The respective diagram is characterized by a high level of linearity. In particular, a comparison of the two diagrams shows 5 and 6th that despite the considerable change in the measurement setup due to the air gap, there was almost no change in the measurement signal of the position data. In contrast to this, with a magnetic or inductive measuring method, a position determination via such a large air gap variation is only possible with considerable effort on the end-of-line test bench, e.g. B. with regard to teaching or linearizing the system is possible.

A rotation of the sensor device 10 around the z-axis (see 1 ) is expressed in a constant offset of the position data over the entire measuring range. If this rotation is due to one-time installation tolerances, the offset can be adjusted once at the end of life (EOL) of the component and is thus corrected for the entire service life.

The encoder element according to the invention 14th can be implemented relatively easily by means of laser printing processes, for example, with direct application to the vehicle component whose position is to be determined being conceivable.

List of reference symbols

10

Sensor device

12

Light source

121

generated light signal

14th

Encoder element

141

Reflective surface

142

Coding structure

143, 143a, 143b

Stripes

16

Light sensor

161

reflected light signal

162

Distribution of pixel values

163a, b, c

rising edge

164a, b, c

falling edge

18th

Evaluation unit

Claims (12)

Sensor device (10) for determining the position of a component for a vehicle, comprising: a light source (12) for generating a light signal (121); a transmitter element (14) which has a reflective surface (141) for reflecting the generated light signal (121), a coding structure (142) with a bit sequence being incorporated on the reflective surface (141); a light sensor (16) for detecting the reflected light signal (161) in order to generate a pixel value distribution (162); and an evaluation unit (18) for decoding the coding structure (142) based on the pixel value distribution (162) in order to determine the bit sequence. Sensor device (10) for determining the position of a component for a vehicle, comprising: a light source (12) for generating a light signal (121); a transmitter element (14) which has a transmission surface for transmitting the generated light signal (121), a coding structure (142) with a bit sequence being incorporated on the transmission surface; a light sensor (16) for detecting the reflected light signal (161) in order to generate a pixel value distribution (162); and an evaluation unit (18) for decoding the coding structure (142) based on the pixel value distribution (162) in order to determine the bit sequence. Sensor device (10) Claim 1 or 2 , wherein the light source (12) and the light sensor (16) are arranged on the same side of the reflective surface (141) of the transmitter element (14). Sensor device (10) according to one of the preceding claims, wherein the coding structure (142) comprises a plurality of strips (143), each of the plurality of strips (143) being assigned a bit. Sensor device (10) Claim 4 wherein the plurality of strips (143) have a first width and a second width, the second width being greater than the first width. Sensor device (10) Claim 4 or 5 , the evaluation unit (18) being designed to identify a rising edge (163a, b, c) and a falling edge (164a, b, c) in the pixel value distribution (162) for each of the plurality of strips (143), to determine a distance between the rising and falling edges (163a, b, c; 164a, b, c). Sensor device (10) according to one of the preceding claims, wherein the coding structure (142) comprises a Gray code and / or is provided on a single charge-coupled chip. Sensor device (10) according to one of the preceding claims, wherein the light source (12) is designed to emit a frequency-modulated light signal. Sensor device (10) according to one of the preceding claims, wherein the evaluation unit (18) is designed to determine position data of the encoder element (14) from the determined bit sequences based on a conversion table. A method for the sensor-based position determination of a component for a vehicle, comprising: a first step in which a light signal (121) is generated by a light source (12); a second step in which the generated light signal (121) is reflected on a reflective surface (141) of a transmitter element (14), a coding structure (142) having a bit sequence being incorporated on the reflective surface (141); a third step in which the reflected light signal (161) is detected by a light sensor (16) in order to generate a pixel value distribution (162); and a fourth step in which the coding structure (142) is decoded by an evaluation unit (18) based on the pixel value distribution (162). A method for the sensor-based position determination of a component for a vehicle, comprising: a first step in which a light signal (121) is generated by a light source (12); a second step in which the generated light signal (121) is transmitted through a transmission surface of a transmitter element (14), a coding structure (142) with a bit sequence being incorporated on the transmission surface; a third step in which the reflected light signal (161) is detected by a light sensor (16) in order to generate a pixel value distribution (162); and a fourth step in which the coding structure (142) is decoded by an evaluation unit (18) based on the pixel value distribution (162). Computer program product that is stored in a data carrier and designed to implement the method according to Claim 10 or 11 performed when the computer program product is executed by a computer.

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