This application is the U.S. National Phase Application of PCT International Application No. PCT/EP2016/068198, filed Jul. 29, 2016, which claims priority to German Patent Application No. 10 2015 217 080.2, filed Sep. 7, 2015 and German Patent Application No. 10 2016 201 783.7, filed Feb. 5, 2016, the contents of such applications being incorporated by reference herein.
The invention relates to a rotation angle sensor system.
Rotation angle sensor systems based on the prior art are frequently used in vehicles with active suspension control, level adjustment or automatic headlamp adjustment. In this case, the housing of the sensor is mounted permanently on the chassis of the vehicle and the wheel or the wheel suspension is coupled to a motion sensor of the rotation angle sensor system via a rod assembly. In this way, it is possible for the inward and outward travel of the wheel relative to the chassis to be picked up.
Rotating with the motion sensor is, by way of example, a magnetic encoder whose angular position is picked up by a Hall element or another sensor. The inward and outward travel of the wheel is thus converted into a measurable rotary motion of the motion sensor.
In this case, the rotation takes place in a bounded angle interval that is, by way of example, between −45° and +45° around a zero point. The zero point then corresponds for the most part to the natural deflection if the vehicle is on a horizontal plane.
Using evaluation electronics, for example in the form of a microcontroller, an initially digital output signal is generated from the sensed angular position. From this, an analog or digital or pulse-width-modulated signal is then generated, the resolution of the digital output signal being reduced to 2{circumflex over ( )}12 bits, that is to say 4096 smallest units (digits). The output signal, for example a voltage, is then transmitted to an electrical controller. On account of the high level of incident electromagnetic radiation and the long cable runs in many vehicles, a higher resolution would lead to impairment of the data in the case of conventional interfaces.
Since, on the one hand, the resolution of the output signal is therefore limited, but on the other hand also only a limited angle range is supposed to be measured, an electrical output signal having recurring intervals is used. If the chosen measurement angle interval is 90°, then the output signal is divided into intervals of 90°, four of which map a rotation angle of 360°.
In generating the digital output signal D(α), a volume of data of 2{circumflex over ( )}14 bits over an angle of 360° was used in this example, corresponding to a volume of data of 2{circumflex over ( )}12 bits over an angle of 90° for the same resolution.
Since the output of the output signal D(α) is limited to a volume of data of 2{circumflex over ( )}12 bits, the most that can be used as the measurement angle interval for the resolution of the output signal D(α) with the internal resolution value is an angle of 90°, as is the case in this example. Although any smaller angle would result in a better resolution of the output signal D(α) that is output, it would be infeasible for many applications.
The case of a larger measurement angle interval is shown by
Expressed another way, if the internal resolution were retained then a data volume of 2{circumflex over ( )}14/3 bits=5462 bits would be necessary for the interval of 120°. However, only 2{circumflex over ( )}12=4096 bits are available, which is why the resolution of the output signal D(α) is worse than the internal resolution in this example.
The output signal profiles of a rotation angle sensor system based on the prior art that are shown in
The volume of data does not have to be reduced only if, as in the example of
Furthermore, the effect of the limitation of the measurement angle interval, shown in
Therefore an aspect of the invention aims to provide a rotation angle sensor system that eliminates the cited disadvantages and is simple and effective in its operation.
As a result of an aspect of the invention involving the resolution of the digital output signal for a measurement angle interval less than or equal to 360° being of the same magnitude as the internal resolution, the advantage is obtained that the internally available resolution can be utilised fully without limiting the measurement angle interval.
According to one development of the invention, the digital output signal in a maximum angle interval from 0° to 360° depicts a unique mapping of the rotation of the motion sensor. Instead of the division into multiple intervals Q1 to Q4 and Q1_b to Q3_b, as depicted in
In the event of sharp deflections, such as may arise as a result of wear on or a stone hitting the vehicle, the measurement angle interval can be exceeded. In this case, the unique mapping ensures that there can be no incorrectly interpreted output signal in the maximum angle interval.
Preferably, the measurement angle interval is within the maximum angle interval. As a result of the uniqueness, every value of the output signal within the maximum angle interval has exactly one particular associated rotation angle of the motion sensor. The measurement angle interval within the maximum angle interval can thus comprise up to 360° without an ambiguous output signal being produced. In addition, shifting the peripheral bounds of the measurement angle interval or altering the zero position angle is also unproblematic. This allows the rotation angle sensor system to be used more flexibly, since the installation position can be chosen freely.
According to a further advantageous embodiment of the rotation angle sensor system 1 according to the invention, the output signal covers a signal range between a signal minimum and a signal maximum and, as defined by a discontinuity, skips to the signal minimum when a rotation angle associated with the signal maximum is exceeded and skips to the signal maximum when a rotation angle associated with the signal minimum is undershot. In this way, the rotation angle sensor system 1 is operable even if the motion sensor completes more than one full revolution.
Preferably, the maximum angle interval has one discontinuity at each of its edges only. This is useful in order to easily provide a unique output signal in the maximum angle interval by utilising the whole signal width.
According to a further embodiment of the rotation angle sensor system 1 according to the invention, the maximum angle interval has exactly one discontinuity in the area between its edges.
Preferably, the measurement angle interval is within an area without a discontinuity. This simplifies the evaluation, for example by a controller.
According to a further embodiment of the rotation angle sensor system 1 according to the invention, the measurement angle interval is within an area that includes the discontinuity. In order to be able to use the output signal further, a controller needs in this case to be capable of detecting the discontinuity, or of interpreting the output signal unambiguously in the area of said discontinuity.
The rotation angle sensor system is expediently configured such that the measurement angle interval comprises the middle of the maximum angle interval, in particular is in the middle of the maximum angle interval. In the event of sharp deflections, such as may arise as a result of wear on or a stone hitting the vehicle, the measurement angle interval can be exceeded. As a result of a measurement angle interval in the middle, the distance from the edges of the maximum angle interval is great on both sides of the measurement angle interval, which means that there can be no incorrectly interpreted output signal.
Preferably, the internal resolution is at least 2{circumflex over ( )}10 bits, advantageously 2{circumflex over ( )}12 bits, preferably 2{circumflex over ( )}14 bits over an angle of 360°.
It is preferred for the measurement angle interval to comprise an angle range of 90°, advantageously 120°, preferably 180°. Such a measurement angle interval is useful for standard rotation angle sensor tasks on a vehicle.
It is expedient for the rotation angle sensor system to have a bracket, wherein the bracket permits mounting of the rotation angle sensor system in different alignments and/or positions on a vehicle.
Referring to
Preferably, there are multiple mounting points available for mounting the motion sensor on the second component of the vehicle.
According to a further aspect of the invention, the object is achieved by an electrical controller that is capable of picking up the rotation angle in the area of the discontinuity from the digital output signal.
In the drawings, in each case in a schematic illustration:
The output signal profiles of a rotation angle sensor system based on the prior art that are shown in
In the graph shown in
Instead of multiple intervals, the range from 0° to 360° is covered by a single maximum angle interval Δα_max. This is bounded by discontinuities at its edges at 0° and 360°. Hence, as defined by the uniqueness, every angle in the maximum angle interval Δα_max has a particular associated value of the output signal D(α) and vice versa.
If a rotation angle sensor system 1 (see
As already in the case of the prior art described in
The volume of data for outputting the digital output signal D(α) (See,
Since the measurement angle interval Δα is for the most part much smaller than 360°, however, a much smaller volume of data is used as a rule, however. However, the unique mapping over 360° means that there is then the possibility of expanding the measurement angle interval Δα, for example in the event of unwanted excessive deflection of the vehicle components or because this is required for a particular application.
Additionally, the measurement angle interval Δα can be shifted within the maximum angle interval Δα_max, for example if the rotation angle sensor system is installed in a different orientation, that is to say with a differently deflected motion sensor.
In the graph of
Despite the discontinuity, the maximum angle range over 360° is defined as a unique mapping of the rotation of the motion sensor. The measurement angle interval Δα is in this case defined such that it does not include the discontinuity.
In the graph of
Reference is made to
The rotation angle sensor system 1 is calibrated in two stages. First, a basic calibration is performed in the factory. This basic calibration comprises, inter alia, the steps of:
In a second stage, installation of the rotation angle sensor system 1 involves the following, inter alia, being performed for calibration:
The rotation angle sensor system 1 is particularly preferably able to be used as a level sensor or the rotation angle sensor system is configured as a level sensor. The installation of level sensors may be subject to the circumstance that the installation position of the level sensors in a vehicle differ significantly from one another. Put another way, the motion sensors of the level sensors are in different orientations at the time of installation, so that the zero positions of the level sensors differ from one another. In particular if the maximum angle interval comprises 360°, it is then irrelevant where the installation position of the motion sensor is, however.
Number | Date | Country | Kind |
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10 2015 217 080 | Sep 2015 | DE | national |
10 2016 201 783 | Feb 2016 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2016/068198 | 7/29/2016 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2017/041959 | 3/16/2017 | WO | A |
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Entry |
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Korean Notification of Reason for Refusal for Korean Application No. 10-2018-7006557, dated Jan. 15, 2019, with translation, 9 pages. |
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Number | Date | Country | |
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20180252552 A1 | Sep 2018 | US |