Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
  • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
  • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
  • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
  • G01D5/142—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage using Hall-effect devices
  • G01D5/145—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage using Hall-effect devices influenced by the relative movement between the Hall device and magnetic fields

Definitions

• the invention relates to a method for the reconstruction of an angle signal from the sensor signal of a rotation angle sensor according to the preamble of claim 1 and a corresponding rotation angle sensor arrangement according to the preamble of claim 6.
• Rotation angle sensors are used in a variety of applications to measure the angular positions of rotating objects. Magnetic or optical sensors are usually used, with which a contactless measurement is possible. An application from the automotive sector is e.g. the determination of the steering wheel or steering angle of a motor vehicle.
• the measuring arrangement shown comprises a sensor 2 arranged at one end of the axis 1 with an evaluation unit 4 connected to it, the sensor 2 interacting with a transmitter 3 arranged in a stationary manner.
• the encoder 3 comprises a permanent magnet, which in the sensor 2 e.g. induced a voltage. Hall sensors, magnetoresistive sensors (MR sensors), magnetotransistors, etc. can be used as the sensor element.
• a typical rotation angle sensor as is often used for the detection of the steering wheel angle in a motor vehicle, has, for example, the characteristic curve shown in FIG. 2a.
• the sensor signal s of the sensor 2 comprises the entire measuring range (for example between -800 ° and + 800 ° steering wheel lock L ), so that the actual steering wheel angle L is output at the output of sensor 2 or evaluation unit 4.
• the sensor signal 7 is shown in steps in FIG. 2b because it is a digitized signal 7 in this example.
• the sensor signal 7 can be from other systems 4 arranged in the vehicle, such as e.g. processed by a vehicle dynamics control system (e.g. ESP: Electronic Stability Program).
• ESP vehicle dynamics control system
• Such a sensor can be realized, for example, from several MR sensor elements.
• the measuring range of the rotation angle sensor comprises only a partial range (from -p to + p) of a total measuring range for a rotation angle ⁇ L.
• the characteristic curve 5 of the sensor is repeated periodically for angles ⁇ L which go beyond the partial measuring range (for example between -120 ° and + 120 °). Between the individual periods of the characteristic curve 5, which can also be referred to as segments S, the characteristic curve 5 shows one in each case Characteristic jump 8. If the partial measuring range of the rotation angle sensor includes, for example, angles between -120 ° and + 120 °, rotation angles ⁇ L which are in this range are clearly displayed. At an angle of rotation of 121 °, on the other hand, the angle of rotation sensor supplies an output signal ⁇ s which corresponds to an angle of rotation of -119 °.
• a rotary movement of an axis, as shown in FIG. 3b with the reference number 6, will therefore lead to the sensor signal 7.
• Such a sensor signal 7 cannot be sent directly from a downstream device 4, e.g. a vehicle dynamics control system, because the sensor signal 7 is not unique.
• the essential idea of the invention is to monitor the sensor signal of the rotation angle sensor and to determine positive or negative signal jumps in the sensor signal. If a signal jump is detected, a segment value is generated, which indicates in which segment of the sensor characteristic curve the currently measured angle of rotation has been since the sensor was initialized. An evaluation unit can determine the actual total angle of rotation (since the sensor was initialized) in a simple manner from the segment value and the sensor signal, and thus an unambiguous angle signal reconstruct. A particularly simple and therefore inexpensive rotation angle sensor can thus be used.
• the positive and negative signal jumps in the sensor signal are determined by threshold value monitoring of the rate of change of the sensor signal. That is, a signal jump is assumed when the rate of change of the sensor signal exceeds a predetermined threshold. Whether the signal jump is positive (from smaller values to larger values) or a negative (from larger values to smaller values) can be determined in a simple manner by comparing the angle values supplied by the angle of rotation sensor.
• SN a predefined segment value
• the segment counter is preferably incremented by 1 when there is a negative signal jump and decremented by 1 when there is a positive signal jump.
• the evaluation unit can easily reconstruct the actual angle signal from the current sensor signal in conjunction with the associated segment value.
• the processing unit preferably adds an angle to the sensor signal, which is a function of the segment value. For example, an angle SN * ⁇ (S) is added to the sensor signal, where SN is the segment value and (S) is an angle corresponding to the segment size.
• a rotation angle sensor arrangement comprises a rotation angle sensor which has a periodic characteristic curve with a plurality of segments, between which jumps in the characteristic curve occur, as well as a processing unit which is able to reconstruct from the sensor signal and a segment value an angle signal which clearly reproduces the actual rotary movement of a device since the initialization of the rotary angle sensor, the processing unit operating as described above.
• FIG. 1 shows an example of a measuring arrangement for measuring an angle of rotation of a rotating axis
• FIG. 2b shows the sensor signal of the rotation angle sensor from FIG. 2a
• 3a shows the sensor characteristic of a known rotation angle sensor with a periodic characteristic
• FIG. 3b shows the sensor output signal of the sensor from FIG. 3a
• 4a shows a sensor signal of a rotation angle sensor with a periodic characteristic
• FIG. 4b shows the counter reading of a segment counter when the signal from FIG. 4a is present
• FIG. 5 shows a flowchart to illustrate the essential method steps in the reconstruction of an angle signal from a sensor signal.
• FIG. 4a shows a sensor signal 7 of a rotation angle sensor 2 with a periodic characteristic curve, as is shown by way of example in FIG. 3a.
• the signal jumps ad in the sensor signal 7 result from the fact that the actual angle of rotation ⁇ L of the shaft 1 extends beyond the partial measuring range limits -p, + p of the angle of rotation sensor 2. This is explained in more detail below using an illustrative example.
• the sensor output signal jumps back a to the sensor output value of the next segment S1.
• the actual angle of rotation ⁇ L of the axis 1 is in the time period tl to t2, that is to say in segment 1 of the sensor characteristic curve of FIG. 3a.
• the angle of rotation ⁇ L again falls below the segment boundary between the segments SO and S1.
• the sensor signal thus jumps to the end value of the segment SO at time t2 (FIG. 4a).
• This positive signal jump is identified by the reference symbol b.
• the actual angle of rotation is therefore in the segment SO. If the axis is turned back further, the angle of rotation then falls below the lower segment limit -p of the segment SO and the sensor signal 1 jumps to the end value of the segment S_ ⁇ with a positive signal jump c (see characteristic curve of FIG. 3a). The actual angle of rotation ⁇ L is thus in the segment S_ ⁇ .
• axis 1 is in the zero position, that is to say in segment SO, when the angle of rotation sensor 2 is initialized. If, on the other hand, axis 1 is in an angular position outside the segment SO, it must Angle signal 2 can still be corrected by this deviation.
• the offset present when the angle of rotation sensor 2 is initialized can be taken into account, for example, by storing the axis position when sensor 2 is switched off (provided axis 1 is not moved when the sensor is switched off).
• sensor 2 is initialized e.g. when switching on the ignition and switching off sensor 2 when switching off the ignition. Since the steering wheel is usually blocked in the park position when the ignition is switched off, the angular position of the steering wheel when the ignition is switched on again corresponds to the position of the steering wheel when it was previously switched off.
• FIG. 5 shows the essential method steps of a method for the reconstruction of an angle signal 9 from the sensor signal 7 of a rotation angle sensor 2, which has a periodic characteristic curve 3 with a plurality of segments S, between which characteristic curve jumps 8 occur.
• the sensor signal 7 is read in a first step 15 and positive and negative signal jumps ad of the sensor signal 7 are recorded in step 16.
• a segment value SN is generated, which indicates in which segment S of the sensor characteristic curve 3 the currently measured angle of rotation ⁇ L lies.
• the evaluation unit 4 can determine the total angle of rotation from the sensor signal 7 and the segment value SN since the sensor 2 was initialized. For this purpose, the evaluation unit 4 adds an angle to the sensor signal, for example 7, which is a function of the segment value SN and the segment width.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
• Length Measuring Devices With Unspecified Measuring Means (AREA)
• Transmission And Conversion Of Sensor Element Output (AREA)

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• 2002
  • 2002-11-28 DE DE10255468A patent/DE10255468A1/de not_active Withdrawn
• 2003
  • 2003-07-08 EP EP03797956A patent/EP1585941A1/de not_active Withdrawn
  • 2003-07-08 WO PCT/DE2003/002261 patent/WO2004051193A1/de not_active Application Discontinuation
  • 2003-07-08 US US10/537,033 patent/US20060225524A1/en not_active Abandoned
  • 2003-07-08 CN CNA038033976A patent/CN1628240A/zh active Pending

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