DE102008054393A1 - Rotational direction determining method for wheel of vehicle, involves determining phase relationship between received signals, and determining rotational direction of rotatable body based on phase relationship using nonius-process - Google Patents

Abstract

The method involves receiving tangential or radial acceleration signals, which are emitted by acceleration sensors (12, 13). A position of deviation factor in the received signals is determined by determining zero crossing and a maximum value of the received signals. The determined deviation factor in the received signals is changed, and a phase relationship between the received signals is determined. A rotational direction of a rotatable body (11) is determined based on the determined phase relationship using a nonius-process. Independent claims are also included for the following: (1) a device for determining a rotational direction of a rotatable body (2) a program having instructions to perform a method for determining a rotational direction of a rotatable body (3) a computer program product having instructions to perform a method for determining a rotational direction of a rotatable body.

Description

State of the art

The The invention relates to a method for determining the direction of rotation a tire by means of two acceleration sensors with different detection direction. Furthermore, the invention relates to a device for implementation a method for determining the direction of rotation of a tire.

In In recent years, the requirements are active and passive Safety systems in vehicles have risen. Because of that The number of security systems used in vehicles has increased always increased. These security systems are on Data relied on a variety of different sensors. To the Safety systems mentioned include tire pressure monitoring systems (Tire Pressure Monitoring System, TPMS) that monitor tire pressure. One pressure sensor measures the tire pressure per wheel and transmits it him, usually wireless, to the vehicle.

In the US 2003/0197603 a method is described by means of which the position of the wheel, for. B. front left, can be determined. In this case, two acceleration sensors whose detection directions are offset at an angle α of greater than 0 or less than 180 ° to each other, the gravitational acceleration on the rotating wheel. This results in 2 sinusoids with an amplitude of 1 G, which correspond to each other by the angle α out of phase. From the phase relationship, the direction of rotation can be derived.

These However, known methods have the disadvantage that when the Sensor is not mounted on the rim but on the tire, there is no continuous sinusoidal oscillation. This follows from the fact that the tire is not round, but in the area of the footprint of the tire is flattened. The change from a rotational one in a translational movement results in the radial direction in a decrease of centripetal acceleration to 0G or tangential Direction (running direction) in a negative acceleration (deceleration).

Disclosure of the invention

Advantages of the invention

The inventive method with the features of independent claim 1 advantageously has a method for determining a direction of rotation of a rotatable body, particular of a wheel, the determination being based on a attributable to the rotation of the rotatable body and of at least one sensor emitted acceleration signal.

The Determining the direction of rotation can thereby by recording a, from a first acceleration signal outputted to a sensor and assignable to the rotation; Picking up a turn, issued by another sensor assignable, further acceleration signal; Determine the position deviation quantities in the recorded acceleration signals; Replacing the specific deviation quantities; Determine a phase relationship between both acceleration signals and / or Determining the direction of rotation of the rotatable body based done on the phase relationship.

advantageous Training and developments of the invention are by allows the measures specified in the dependent claims.

In In a preferred embodiment, the determination is made the position of the deviation quantities by a Determining a zero crossing of the recorded signal and / or by a determination of a maximum value of the received signal.

According to the invention the step replacing the deviation quantities the Removal of a signal component before and after the specified time Contain deviation quantity and / or the interpolation of the distant signal component.

By the use of several, mutually different determination methods, as well as At least one replacement step may be the robustness of the determination increase.

In In a preferred embodiment, the determination is made the rotational speed by scanning the two sensors to one first time t1. Thus one obtains the signals a1 and a2 at time t1. From these two signals a1 and a2 is the Arctangent formed and the angle between the two signals a1 and a2 determined. Subsequently, both sensors sampled at a second time t2. This gives the signals a1 and a2 at time t2. From the signals a1 and a2 at the time t2, in turn, by means of the Arkustanges the Angle determined. From the change of the angle between The times t1 and t2 can now be the angular velocity of the individual Signals are determined. The sign of the angular velocity indicates the direction of rotation.

Further, from the signals a1 and a2 at time t1 and / or signals a1 and a2 at time t2, the phase relationship / phase difference α be determined between the signals a1 and a2. From the phase relationship between the signals, the direction of rotation can be determined.

According to the invention the angle between the signals a1 and a2 also by any other suitable trigonometric or numerical methods are determined.

According to the invention the recorded acceleration signal is a tangential and / or be radial acceleration signal.

in the According to the invention, a deviation quantity an effect of a systemic transmission weakness (Shock) to be a useful signal (sensor signal). A variance can also a deviation from an expected, statistical, empirical and / or be previously known waveform.

According to the present invention refers to the footprint of the Tire the surface portion of the tire surface, which communicates with the ground.

One Another aspect of the invention relates to a program for execution by a data processing system, the program at the Execution in a computer or a control unit the steps of the method according to the invention performs.

Further the invention relates to a data carrier, wherein on the Disk a program to carry out the is stored according to the invention.

Brief description of the drawings

The The invention will be described below with reference to the accompanying drawings exemplified in more detail. Show it:

1 a schematic representation of a wheel with two acceleration sensors;

2 a schematic representation of recorded acceleration signals;

3 the course of a tangential acceleration signal;

4 the course of a radial acceleration signal;

5a a schematic representation of a tangential acceleration signal;

5b a schematic representation of a tangential acceleration signal without deviation amounts;

5c a schematic representation of a tangential acceleration signal after interpolation; and

6 a block diagram of a circuit arrangement.

embodiments the invention

1 schematically represents a wheel 11 of a vehicle (not shown) that is on a ground 14 rolls. At the wheel 11 are two acceleration sensors 12 . 13 appropriate. The sensors 12 . 13 are offset by an angle α greater than 0 or less than 180 ° to each other. The wheel can consist of a rim and a tire. The sensors are mounted on or in the tire. Each sensor may be a sensor module that is adjacent to an acceleration sensor 12 . 13 still has a pressure sensor and / or a temperature sensor. On the bike 11 and the acceleration sensors 12 . 13 the gravitational acceleration G acts as the wheel turns 11 acts on the acceleration sensors 12 . 13 a centripetal force 12a . 13a in the radial direction. This centripetal force 12a . 13a is proportional to the rotational speed of the wheel 11 , In the area of the footprint of the tire goes the rotational movement of the sensors 12 . 13 in a translational movement over. This change results in the radial direction in a decrease of the centripetal acceleration to 0G or in the tangential direction (running direction) in a negative acceleration (deceleration), which acts on the sensors. The change of the acceleration both in the tangential and in the radial direction are significant, ie the sinusoidal course of the sensor signals is superimposed by accelerations of higher amplitude so-called shocks.

In 2 is the course of the sensors 12 . 13 delivered acceleration signals 22 . 23 shown schematically. The amplitude of the signals 22 . 23 is proportional to the rotational speed of the wheel 11 , On the abscissa of in 2 The diagram shown is the angular position φ of the acceleration signals 22 . 23 applied. On the ordinate of in 2 As shown in the diagram, the acceleration a is plotted in multiples of the gravitational acceleration G. With 21 is the phase shift α between the signal 22 of the sensor 12 and the signal 23 of the sensor 13 specified.

3 shows the course of the output from a sensor tangential acceleration signal 31 , On the abscissa of in 3 The diagram is plotted the time course. On the ordinate of in 3 In the diagram shown, the acceleration a is plotted in multiples of the gravitational acceleration G in a linear scale, the signal being able to be inverted. With the reference number 32 is the maximum value of the signal at the transition from a rotational to a translational movement and designated by the reference numeral 33 is the maximum value of the signal during the transition from a translational to a rotational movement called the so-called deviation quantities.

In 4 is the course of the output from a sensor radial acceleration signal 41 shown. On the abscissa of in 4 The diagram is plotted the time course. On the ordinate of in 4 In the diagram shown, the acceleration a normalized to 1 G is plotted in multiples of the gravitational acceleration G in a linear scale, the signal being able to be inverted. With the reference number 42 is the maximum value of the signal at the transition from a rotational to a translational movement and designated by the reference numeral 43 is the maximum value of the signal during the transition from a translational to a rotational movement called the so-called deviation quantities.

5a shows a representation of a tangential acceleration signal. This signal was filtered by a low pass filter to remove higher frequency vibrations. The corner frequency of the filter is between 50 Hz and 100 Hz. The signal shown corresponds to a logarithmic signal 3 , The logarithmic representation clearly shows the sinusoidal oscillation superimposed by tangential shocks. It can also be seen that the shocks are orders of magnitude faster than the sine wave generated by the wheel rotation.

In 5b is an acceleration signal shown schematically, in which the shocks have been removed from the signal. For this purpose, one makes use of the fact that the shocks on the one hand periodically superimposed on the signal and on the other hand, that their width is relatively constant with respect to a Radumdrehung. The width of the shocks is dependent on the geometry of the footprint of the tire and is typically at 3 to 10% of the wheel circumference (length) or a Radumdrehung (duration).

The following procedures are available to determine the shocks. It detects two zero-crossings of the sine wave of the acceleration signal. Then you cut starting from the time center of the signal max. 10% of a period before and after the middle of the signal. In another method, the shock can be determined by the max. Peaks are detected in the signal. The two peaks 32 . 33 are a measure of the length of the shock or the length of the signal that must be removed from the original signal. Since time before and after the peaks are usually still unwanted acceleration values, it is preferable to cut a period of time from the signal, which is slightly larger than the difference between the two peaks. Again, the period or wheel speed can be helpful. The larger the period, the larger the area to be cut out, which at max. 20% of a period is.

5c shows the sinusoidal acceleration signal reconstructed by interpolation from the two incomplete half-waves.

The Signal of the further acceleration sensor will be the same signal processing subjected. Then you get two sine waves whose Phase relationship can be evaluated more easily.

The method can also be used for radial acceleration signals. Here arises accordingly 4 a superimposition of the +/- 1 G sine wave with the radial signal. The radial shock, but can be extracted by the same method. It must be taken into account that additional offset compensation must be carried out here. In contrast to the tangential direction, the +/- 1 G oscillation is superimposed on the offset of the centripetal acceleration.

Around the demand on the dynamics of the sensor does not become too large To let the speed range in which the measurement is performed can be made will be limited. In turn, the period duration is suitable for this purpose. Its reciprocal is the wheel speed frequency. exceeds this one particular value, e.g. B. 14 Hz (~ 100 km / h), the measurement becomes canceled. Alternatively, this case can be determined if the accelerometer permanently delivers values that are at the Limit or outside the measuring range.

In a further advantageous embodiment, the detection direction of the sensors is not tangential or radial but at an angle β of greater than 0 or less than 90 ° between the two directions. In this case, the two sensors differ with respect to the angle β, either in magnitude or in sign. The resulting signal is a hybrid of the two previous cases. Superimposed on the sine wave are two shocks that correspond to those in the tangential and radial directions, but with a smaller amplitude. The shocks can be removed just as well with the aforementioned methods. In addition, the sinusoidal oscillation has an offset by the centripetal acceleration of all This is less than that in the purely radial direction. Again, an offset compensation must be performed.

In In a further advantageous embodiment, the signal is only in Scanned area of sinusoidal oscillation. The range of shocks is not scanned. This eliminates the need to extract the Shocks from the recorded signal. However, this must be known be when the shock occurs and when the exit from the footprint of the tire takes place. This can be z. B. by a single scan a Radumdrehung be realized with low sampling frequency. Starting from the last exit can with the help of the wheel speed of the next entry into the footprint of the Tire can be calculated. After leaving the footprint of the tire, the sampling of the signal begins. Just before the next one The sampling is stopped and if necessary after the Exit resumed again.

In 6 Figure 3 is a schematic block diagram of an alternative software-based embodiment of the proposed device 60 for detecting the direction of rotation of a tire. The proposed device includes a processing unit PU 61 , which may be any processor or computer with a control unit, wherein the control unit controls based on software routines one in a memory MEM 62 stored program. Program commands are taken from memory 62 brought and into the control unit of the processing unit 61 loaded to perform the processing steps of the functionalities described above. These processing steps may be performed on the basis of input data DI and generate output data DO, wherein the input data may correspond to at least one acceleration signal assignable to the rotation of the tire, and the output data DO may correspond to a signal corresponding to the direction of rotation of the tire.

It has been a method and apparatus for determining a direction of rotation a rotatable body, in particular a wheel, described the determination based on one of the direction of rotation of the rotatable Body assignable, issued by at least one sensor Acceleration signal, through the steps picking up a, from a sensor delivered, the direction of rotation assignable, first Acceleration signal; Picking up one, from another sensor delivered, the direction of rotation assignable, further acceleration signal; Determine the position of deviation quantities in the recorded acceleration signals; Replacing the specific deviation quantities; and determining the direction of rotation of the rotatable body based on the phase difference α between both acceleration signals he follows.

It It is noted that the proposed solutions according to the above-mentioned embodiments as a software module (s) and / or Hardware modules) in the corresponding function blocks can be implemented. It is also pointed out that the present invention is not limited to the above embodiments is limited, but also with other sensor modules can be applied.

Out From the above, it becomes clear that while preferred and exemplary embodiments illustrated and described were, various changes can be made without departing from the spirit of the invention. Accordingly the invention should not be limited by the detailed description of the preferred and exemplary embodiments thereof be limited.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• US 2003/0197603 [0003]

Claims (10)

Method for determining a direction of rotation of a rotatable body ( 11 ), in particular a wheel, the determination being based on a rotation of the rotatable body that can be assigned to at least one sensor ( 12 . 13 ) is performed by the following steps: - picking up one of a sensor ( 12 ) and assignable to the rotation first acceleration signal ( 22 ; 31 ; 41 ); - picking up one of another sensor ( 13 ) delivered to the rotation assignable further acceleration signal ( 23 ; 31 ; 41 ); Determining the position of deviation quantities in the recorded signals ( 22 . 23 ; 31 ; 41 ); Replacing the determined deviation quantities in the recorded signals; Determining a phase relationship between the recorded signals ( 22 . 23 ; 31 ; 41 ); and determining the direction of rotation of the rotatable body ( 11 ) based on the determined phase relationship. Method according to claim 1, characterized in that the position of a deviation quantity is determined by a determination of a zero crossing of the recorded signal ( 22 . 23 ; 31 ; 41 ) is determined Method according to Claim 1, characterized in that the position of a deviation variable is determined by determining a maximum value of the recorded signal ( 22 . 23 ; 31 ; 41 ) is determined. Method according to at least one of the preceding Claims, characterized in that the step replacing the deviation would be the removal of a signal component in time before and after the determined variance. Method according to claim 4, characterized in that that the step of replacing the deviation quantity contains the interpolation of the removed signal component. Method according to at least one of the preceding Claims, characterized in that the direction of rotation determined on the basis of a vernier method. Method according to at least one of the preceding claims, characterized in that the recorded acceleration signal ( 22 . 23 ; 31 ; 41 ) is a tangential or radial acceleration signal. Device for determining a direction of rotation of a rotatable body ( 11 ), in particular a wheel, the determination being based on a rotation of the rotatable body that can be assigned to at least one sensor ( 12 . 13 acceleration signal output, comprising: - at least one recording device for recording the rotation of the body and assignable by at least one sensor ( 12 . 13 ) output accelerator signals; A signal conditioning device for determining and replacing deviation quantities in the recorded signals ( 22 . 23 ; 31 ; 41 ); A phase determination device for determining a phase relationship between the recorded signals ( 22 . 23 ; 31 ; 41 ); and a rotation direction determining means for determining the rotational direction of the rotatable body based on the determined phase relationship. Program for execution by a data processing system, characterized by the fact that the program is running in a computer or controller, a method according to one of claims 1 to 7 performs. Computer program product with program code based on a machine-readable carrier is stored for execution The method according to any one of claims 1 to 7, when said Program running on a computer or controller.