DE102010031209A1 - Pedal distance measuring device for motor car, has base body with attaching unit for mounting pedal distance measuring device at pedals or in base body, and slant sensor and contactless working distance sensor arranged in base body - Google Patents

Abstract

The device has a base body with an attaching unit for mounting the pedal distance measuring device at pedals (3) or in the base body, where the base body comprises a quick-locking mechanism element. A slant sensor and a contactless working distance sensor (42) are arranged in the base body. A force sensor is arranged in the base body. A microcontroller comprises a wireless data communications equipment arranged in the base body. The attaching unit comprises a tensioning unit for fixing the base body on the pedals. An independent claim is also included for a method for measuring a pedal distance.

Description

The invention relates to a method and a device for pedal travel measurement.

Due to the ever-increasing presence of electronic systems in modern motor vehicles, it is necessary to establish in the main investigation test methods to ensure the error-free operation of these electronically controlled systems.

In the main inspection of vehicles, among other things, the brake is evaluated depending on the pedal position and the brake pressure on the axles. This assessment is subjective and strongly dependent on the examiner performing the main study. The measurement of the pedal position and a specification of the relationship of the pedal position to the brake pressure can make this objective. For this purpose, various solutions have been proposed.

Out DE 10 2004 041 733 A1 is a device for detecting a force and a path on a pedal mechanism, in particular for the detection of forces applied to a foot or device-operated pedal in a motor vehicle and for detecting the effect of these forces caused pedal travel, consisting of a housing and a tread plate which can be acted upon by a pedal actuation force, the housing being releasably attachable to the pedal via an assembly configured as an adapter, and wherein measuring elements are arranged in the housing whose signals are fed wirelessly to an evaluation device, characterized in that the housing is designed as a separate deformable body, in the interior sensors for measuring pedal force and pedal travel are arranged, wherein the deformable body via a clamping device and designed as a separate assembly adapter is detachably fastened to the pedal. As a force sensor, a strain gauge bridge and an acceleration sensor is proposed as a displacement sensor.

DE 10 2005 025 066 A1 complements this device to the effect that the housing of the measuring system is designed as a mounting bracket for all sensors and evaluation, that the housing simultaneously acts as an expansion body for the force measurement and that in the interior of the housing, a sensor for measuring the pedal angle is integrated. In this case, at least one inclination sensor can be integrated as a displacement / angle sensor and a gyrometer can be integrated into the housing for dynamic displacement / angle measurement.

Based on this prior art, a device and a method for pedal travel measurement are now proposed, which enable a highly accurate determination of a pedal travel from a non-contact distance measurement with respect to a reference surface.

The device for pedal travel measurement comprises a base body with a fastening means for attaching the device to a pedal, an inclination sensor arranged on or in the base body, and a non-contact distance sensor arranged on or in the base body.

Under a tilt sensor while a sensor to be understood, the changes in its position, d. H. its angle to the vertical, d. H. opposite to the direction of gravity. Known tilt sensors have the disadvantage that they also respond to acceleration other than gravity. Occasionally this problem is alleviated by the sensor having damping. However, this reduces the response time of the sensor, so that in any case with measurement inaccuracies is to be expected when unwanted accelerations act. This may even be accelerations resulting from the operation of the pedal.

A non-contact distance sensor is to be understood as meaning a sensor which emits a measurement signal, for example light, for example infrared or laser light, or sound, for example ultrasound, which receives a measurement signal reflected from a remote object, for example a reference surface, and the distance to the sensor Reference surface, for example by transit time measurement, triangulation or other customary methods determined.

The device makes it possible to detect the inclination and the distance of the pedal relative to a reference surface, for example the vehicle floor, simultaneously. In connection with the method described below can be determined after previous calibration with the proposed device generalized Betätigungsweggrößen with high accuracy and low susceptibility.

In a further development, a force sensor is also arranged on or in the main body. This makes it possible to simultaneously determine the actuation force of the pedal, whereby the relationship between actuation travel and actuation force of the pedal can be determined and displayed.

In a specific embodiment of the device, the base body is a housing which at least partially encloses the sensors. The term "at least partially includes" means that Of course, a non-contact distance sensor of a housing may not be so completely obscured that no measurement signals can be sent or received, and that a force sensor must still be acted upon when installed in a housing with an actuating force, so that a measurement is possible. However, such restrictions do not exist with respect to a tilt sensor.

According to a further embodiment, it can be provided that a microcontroller is also arranged on or in the main body. The microcontroller can take on the further processing of the measurement signals coming from the sensors, for example, make corrections that normalize the measurement signals and / or relativise, as will be explained in connection with the method also proposed below. In addition, the microcontroller can process the measurement signals or measured values in such a way that they are suitable for wireless transmission to an evaluation device, for example a computer.

Alternatively, the microcontroller can also be located outside the device and, for example, by cables with the device, i. H. be connected to the sensors. The microcontroller can also have a display device, for example an LCD display, and thus combine the functions of an evaluation device and a display device.

Embodiments are also included in which the microcontroller is part of an evaluation device, for example a computer, and the computer is connected to the device by cables or the measured values of the sensors are transmitted wirelessly to the computer.

For this purpose, it can further be provided that a wireless data transmission device is also arranged on or in the main body. The wireless communication is advantageously electromagnetic, so for example optically or by radio waves. This presupposes that the evaluation device has corresponding receiving devices for receiving the signals transmitted by the data transmission device. Both the data transmission device of the proposed device and the evaluation device are advantageously set up both for transmitting and for receiving measurement signals, commands, etc. in order to enable bidirectional communication between the device and a microcontroller and / or the evaluation device.

In the proposed device can further be provided that the fastening means comprises a clamping means for clamping the body to a pedal. The tensioning means may, for example, be a clamping device or strap which is adaptable to different circumferences of pedals to ensure a secure hold of the device on the pedal.

According to a further embodiment, the fastening means comprises a base with a quick-release element and the base body has a corresponding thereto quick-release element. A base with a quick-release element in this sense, for example, a base plate with a linear guide, for example, two oppositely disposed grooves be. In this case, the corresponding quick-release element of the base body would be an opposite arrangement of two projections which engage in the grooves of the base plate when the base body is inserted therein.

• – an einem Pedal ein Neigungssensor und ein berührungsloser Abstandssensor angebracht werden (Installation),
• – zwischen einer Nullstellung und einer Maximalstellung des Pedals die Messwerte des Neigungssensors und des Abstandssensors erfasst, aufeinander abgebildet und relativiert werden (Kalibrierung),
• – beim Betätigen des Pedals zumindest die Messwerte des Abstandssensors erfasst und in eine relative generalisierte Betätigungsweggröße umgerechnet werden (Messung).

Furthermore, a method for Pedalwegmessung is proposed in which a relative generalized Betätigungsweggröße of the pedal is determined from the distance of the pedal to a reference surface, wherein

• - a tilt sensor and a non-contact distance sensor are attached to a pedal (installation),
• Between a zero position and a maximum position of the pedal, the measured values of the inclination sensor and of the distance sensor are recorded, imaged on each other and relativized (calibration),
• - When pressing the pedal, at least the measured values of the distance sensor are detected and converted into a relative generalized Betätigungsweggröße (measurement).

A change in inclination of a pivotally mounted on a pivot point pedal is identical to the associated angle change. Since the angle change is proportional to the path change along the circular path described by the pedal, there is thus a linear relationship between the change in inclination and the actuation path of the pedal. Pedal angle and pedal travel are therefore equivalent to the desired measurement and are hereinafter referred to uniformly as generalized Betätigungsweggrößen.

Measurements of the inclination change of the pedal, however, are not possible with known measuring devices, especially with high accuracy, if the vehicle in which the pedal is installed acts on accelerations that can result from normal driving, but also from vehicle tests on chassis dynamometers or the like (parasitic accelerations). Therefore, a generalized Betätigungsweggröße obtained by a tilt sensor only with high accuracy when the vehicle is at rest.

A change in the distance of the pedal or the attached measuring device against a reference surface, as for example, the vehicle floor is, in contrast, for almost all practically relevant reference surfaces is not proportional to the path or angle change, d. H. There is no linear relationship between the change in distance and the generalized actuation path size. The reasons for this are that the beam path of a non-contact distance sensor changes with the inclination of the pedal and that, for practically relevant reference surfaces, the distance between the current position of the mounted on the pedal distance sensor on its circular trajectory and the current projection point of the distance sensor emitted signal on the reference surface non-linear changes.

Nevertheless, the detection of the change in the distance of the pedal to a reference surface as the basis for determining a generalized Betätigungsweggröße the invaluable advantage that they are largely insensitive to parasitic accelerations.

The basic idea of the invention is therefore to use a robust measuring method for determining a generalized actuation path size and to calibrate the measuring device used for this purpose before the start of the actual measurement, using an auxiliary measuring device that is less resistant to interference but has high accuracy. This calibration therefore takes place in the idle state in which parasitic accelerations do not occur.

In the context of the intended use of the device described herein and the proposed method, absolute values of the generalized actuation path magnitudes are not of interest. Rather, as a result of these measurements, statements are required as to what proportion of the available actuating travel in a particular situation, ie. H. a certain position of the pedal, starting from zero position. It is therefore appropriate to relatively indicate the position of the pedal within the range between the zero position and the maximum position, for example as a percentage of the total possible path.

The relativization of the generalized Betätigungsweggröße therefore means that each position of the pedal between the zero position (corresponds to 0%) and the maximum position (corresponds to 100%) to assign a corresponding percentage. This makes the measurement independent of the specific circumstances of a particular vehicle type, such as the absolute pedal travel, which may vary from vehicle type to vehicle type. It is crucial that after a predetermined proportion of the maximum possible actuating travel a certain braking effect is achieved.

Despite the disadvantages of inclination sensors described above, in particular with regard to their susceptibility to interference, it may nevertheless be appropriate for the measurement values of the distance sensor to be additionally recorded during the measurement and converted into a relative generalized actuation path variable. In particular, when performing on a chassis dynamometer, the parasitic accelerations are relatively low compared to the relative driving, so that a simultaneous measurement of the distance sensor and the inclination sensor, for example, to carry out plausibility checks can be helpful, for example, to detect defects of the distance sensor in time and the measurement if necessary, abort or reject. Should this occur, the tilt sensor may still be used to perform emergency operation of the device.

Analogous to the device described above, in the method during the installation, furthermore, a force sensor can be attached to the pedal and, in addition, the measured values of the force sensor can be detected during the measurement.

The calibration of the device is advantageously carried out in one step, d. H. a complete actuation of the pedal with simultaneous data acquisition. Alternatively, however, the method may also be configured such that during the first operation of the pedal, the zero position and the maximum position are determined first, and then during a second actuation of the pedal in the range between the zero position and the maximum position of the pedal, the measured values of the pedal Tilt sensor and the distance sensor are detected, the detection of the readings of the tilt sensor and the distance sensor is terminated when the maximum position is reached.

This feature acquires significance in particular with regard to a far-reaching automation of the method in the context of a software that is executed on an evaluation device, which simultaneously acts as a control device for the device described above.

For example, this evaluation device can start the measured value acquisition in response to a user command and signal the user to begin a first measured value acquisition. The pedal is then completely intervened by the user once Zero position and maximum position moved back and forth. The software detects the zero position of the pedal, which corresponds to the measured values of the sensors in the initial position of the pedal at the beginning of the measurement, and the maximum position of the pedal, which corresponds to the maximum values (maximum inclination change and maximum distance change) of the measured values determined by the sensors.

Subsequently, the evaluation device can start the measured value acquisition again automatically or in response to a user command and signal the user to start a second measured value acquisition. The pedal is then once again moved back and forth between the zero position and the maximum position by the user. The software now records the measured values of the sensors continuously or with a defined or selectable sampling rate between the already known positions. This second measurement is used to create a correction function or a correction table.

In one refinement of the method, it is therefore provided that a correction function which continuously reproduces the functional relationship between the measured variables of the inclination sensor and the distance sensor is determined during the calibration for mapping the measured values of the inclination sensor and the distance sensor.

In another embodiment of the method, it is provided that in the calibration for mapping the measured values of the inclination sensor and the distance sensor to each other, a correction table is determined which contains conversion factors for discrete measured values.

A correction function in this sense can be, for example, a continuously acquired measurement signal or a mathematical expression generated from a continuous measurement signal or discrete measurement values, which sets the measurement signals of both sensors relative to each other and enables the conversion of the one measurement variable into the other measured variable. In this case, known approximation, regression and interpolation methods, for example the method of least squares, spline interpolation, etc., can be used.

A correction table in this sense can be a table of values which uniquely maps discrete measured values of a non-contact distance sensor to discrete measured values of the inclination sensor. Of course, a correction table can also be determined in addition to a correction function.

It goes without saying that correction functions and correction tables can be realized as a software function and / or values stored electronically.

The invention will be explained in more detail with reference to an embodiment and associated drawings. Show

1 a schematic representation of the measurement behavior of a non-contact distance sensor on a pedal,

2 a schematic representation of the measuring behavior of a tilt sensor on a pedal,

3 in three views an embodiment of the main body of the device,

4 an overall view of the device according to the embodiment,

5 the base of the fastening means of the device according to the embodiment,

6 attached to a pedal attachment means of the device according to embodiment

7 the attachment of the device to hanging and standing pedals,

8th the basic principle of calibration, and

9 an exemplary implementation of the method as a schematic flowchart.

In 1 is the determination of the pedal position by a non-contact distance sensor 42 , For example, a laser sensor shown. The distance sensor 42 is at the footplate of the pedal 3 attaches and determines the distance of the pedal 3 to a reference plane 5 , in the embodiment to the vehicle floor, continuously or incrementally, while the pedal 3 is moved by emitting a light beam and the reflected light beam is received. The pedal 3 is articulated and therefore moves on a circular path around the hinge point. The distance sensor 42 is on the pedal 3 attached and therefore turns with the pedal 3 depending on the operating angle of the pedal 3 around its own axis. In the exemplary embodiment, the determination of the distance takes place according to the triangulation method, ie the change in position of the reflected light spot on the detector and not the transit time of the light is determined.

In 2 is the determination of the pedal position by a tilt sensor 41 shown. Of the tilt sensor 41 is also on the pedal 3 attached. It will change the angle of the pedal 3 measured with respect to the vertical, wherein the measured value acquisition takes place continuously or incrementally while the pedal 3 is moved.

3 shows an exemplary housing, as the main body 1 can serve for the device. In the housing there are recordings for the tilt sensor 41 , a force sensor 43 and the non-contact distance sensor 42 , The housing is designed so that the force sensor 43 remains accessible from above and the distance sensor 42 accessible from below. Thus, the actuation force acting from above can be determined and it can be the distance down to a reference plane 5 be determined.

In 4 is shown up to the fastener complete device in which the housing 1 upwards with a lid 11 and to the side with a side cover 12 is closed, but which has an opening in which the actuating plate 431 of the force sensor 43 is arranged. The distance sensor 42 partially protrudes down from the housing 1 out. At the bottom of the case 1 is a quick release means, in the exemplary embodiment, a connection plate 13 , whose function will be explained in more detail below.

5 shows a pedestal 21 , the part of the fastener 2 for attaching the device to a pedal 3 is. The base 21 has two guides 23 for receiving the connection plate 13 of the housing 1 on, in which the connection plate 13 can be inserted. Furthermore, the pedestal has 21 two tours 22 for a clamping device for clamping the body 1 on a pedal 3 whose function will be explained in more detail below.

In 6 is shown as the socket 21 by means of a tensioning means, which in the embodiment, a textile strap 24 with a ratchet fastener 25 for adaptation to different sized pedals 3 is executed. The guides 23 for receiving the connection plate 13 are laterally accessible, leaving the case 1 can be inserted laterally.

7 shows two variants of the attachment of the device to a pedal 3 , With a hanging pedal 3 it is recommended to attach as shown in the left illustration. Here are the pictures 23 of the pedestal 21 for the connection plate 13 of the housing 1 horizontally, leaving the case 1 with the connection plate 13 laterally in the shots 23 of the pedestal 21 can be inserted.

The right-hand illustration, on the other hand, shows an advantageous attachment of the device to a standing pedal 3 , Here is the pedestal 21 so on the pedal 3 attached that shots 23 for the connection plate 13 run vertically, ie are rotated by 90 ° with respect to the left-hand display. The housing 1 can do so with its connection plate 13 from top to bottom in the shots 23 of the pedestal 21 be inserted. To prevent the connecting plate from slipping 13 to avoid pointing out the shots 23 in the pedestal 21 a limit in the form of a stop, which prevents this.

Because the connection plate 13 of the housing 1 square, the housing can 1 in both mounting variants despite twisted base 21 be mounted in the same position, so that the distance sensor 42 and the tilt sensor 41 work correctly.

8th shows the process of calibration, which can also be understood as a learning process for the device, because it must be performed on each vehicle type because of the different conditions with respect to the reference plane.

The distance sensor supplies a nonlinear measurement value series, as already explained above. The tilt sensor, on the other hand, provides a linear series of measurements because the vehicle does not experience external acceleration during calibration and the pedal is actuated slowly and evenly. Optionally, measured values of the actuating force can also be detected. Subsequently, the measured values of the distance sensor are mapped to the measured values of the inclination sensor, i. H. the measured values of the distance sensor are linearized with the aid of the measured values of the inclination sensor. This process is symbolized by the arrows in the diagram on the right. Subsequently, only from the measured values of the distance sensor with high accuracy and low susceptibility to interference, a relative generalized Betätigungsweggröße be determined.

In 9 the calibration of the device is shown as an example and greatly simplified as a program flowchart.

First, the device, if appropriate together with an external evaluation device which can simultaneously control the measurement and store the measured values, is initialized. If one or more sensors work analogously, then it makes sense to carry out an analog-to-digital conversion in order to process the measured values digitally.

If the user gives the command to start the calibration, this is done as described in detail above. In the illustrated flowchart it is provided that the teach-in process is performed in two steps, wherein the size of the measuring range is determined in the first step and in the second step measured values are determined within the measuring range, as also described in detail.

Then, the distance sensor readings are linearized and normalized (adjusted and calculated) to a range of 0 to 100%, and finally the readings and / or the result of the calibration are visualized, i. H. displayed on a display.

If measured values of the actuation force were also determined, these can also be evaluated and displayed, for example, as a function of the relative generalized actuation path size.

LIST OF REFERENCE NUMBERS

1

Basic body, housing

11

cover

12

side cover

13

Quick release, connection plate

2

fastener

21

base

22

Guide for strap

23

Quick-release fastener, guide for connection plate

24

strap

25

ratchet

3

pedal

41

tilt sensor

42

non-contact distance sensor

43

force sensor

431

operating plate

5

reference surface

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102004041733 A1 [0004]
• DE 102005025066 A1 [0005]

Claims (16)

Device for pedal travel measurement, comprising a basic body ( 1 ) with a fastening means ( 2 ) for attaching the device to a pedal ( 3 ), one on or in the main body ( 1 ) arranged tilt sensor ( 41 ) as well as one on or in the main body ( 1 ) arranged non-contact distance sensor ( 42 ). Device according to claim 1, characterized in that on or in the basic body ( 1 ), a force sensor ( 43 ) is arranged. Apparatus according to claim 1 or 2, characterized in that the basic body ( 1 ) is a housing that the sensors ( 41 . 42 . 43 ) at least partially includes. Device according to one of claims 1 to 3, characterized in that on or in the basic body ( 1 ) is further arranged a wireless data transmission device. Device according to one of claims 1 to 4, characterized in that on or in the base body ( 1 ) Further, a microcontroller is arranged. Device according to one of claims 1 to 4, characterized in that outside the device, a microcontroller is arranged and connected by cables to the device. Apparatus according to claim 6, characterized in that the microcontroller has a display device. Apparatus according to claim 6 or 7, characterized in that the microcontroller comprises a wireless data transmission device. Device according to one of claims 1 to 8, characterized in that the fastening means ( 2 ) a clamping means for clamping the base body ( 1 ) on a pedal ( 3 ). Device according to one of claims 1 to 9, characterized in that the fastening means ( 2 ) a socket ( 21 ) with a quick-release element ( 23 ) and the basic body ( 1 ) a corresponding quick-release element ( 13 ) having. Method for pedal travel measurement in which a relative generalized actuation path of the pedal ( 3 ) from the distance of the pedal ( 3 ) to a reference surface ( 5 ), wherein - on a pedal ( 3 ) a tilt sensor ( 41 ) and a non-contact distance sensor ( 42 ) (installation), - between a zero position and a maximum position of the pedal ( 3 ) the measured values of the inclination sensor ( 41 ) and the distance sensor ( 42 ), mapped and relativised (calibration), - when the pedal is pressed ( 3 ) at least the measured values of the distance sensor ( 42 ) and converted into a relative generalized Betätigungsweggröße (measurement). A method according to claim 11, characterized in that during the measurement additionally the measured values of the distance sensor ( 42 ) and converted into a relative generalized Betätigungsweggröße. A method according to claim 11 or 12, characterized in that during installation further comprises a force sensor ( 43 ) on the pedal ( 3 ) and additionally the measured values of the force sensor ( 43 ). Method according to one of claims 11 to 13, characterized in that during the calibration during a first actuation of the pedal ( 3 ) first the zero position and the maximum position are determined and then during a second actuation of the pedal ( 3 ) in the range between the zero position and the maximum position of the pedal ( 3 ) the measured values of the inclination sensor ( 41 ) and the distance sensor ( 42 ), wherein the acquisition of the measured values of the inclination sensor ( 41 ) and the distance sensor ( 42 ) is terminated as soon as the maximum position is reached. Method according to one of claims 11 to 14, characterized in that in the calibration for mapping the measured values of the inclination sensor ( 41 ) and the distance sensor ( 42 ) a correction function is determined which determines the functional relationship between the measured variables of the inclination sensor ( 41 ) and the distance sensor ( 42 ) continuously reproduces. Method according to one of claims 11 to 15, characterized in that in the calibration for mapping the measured values of the inclination sensor ( 41 ) and the distance sensor ( 42 ) a correction table is determined which contains conversion factors for discrete measured values.

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