The invention relates to a sensor evaluation arrangement and a method
for operating a sensor arrangement.
A known Sensorauswerteanordnung shows the US 5,477,135
, In this, a HALL sensor is coupled to a control device which serves to calibrate the sensor. The arrangement includes a sensor, a supply device, an evaluation device and the control device, which determines various parameters during the calibration process.
From the DE 10 2004 010 613 A1
a magnetic field sensor is known which is supplied by a supply device and emits a sensor signal to an evaluation device. This generates an evaluation signal. A feedback device to which the evaluation signal is supplied is connected to the supply device. The control circuit improves the noise behavior of the magnetic field sensor.
The DE 101 54 154 A1
finally shows a protractor with offset compensation. From the DE 101 54 498 A1
a Hall probe system is known in which a device generates an electrical control voltage as a function of an influencing parameter of the Hall region.
In many areas, input devices are used that control the angle of rotation
a moving body
detect. These input devices
For example, in automobiles, aircraft, or game consoles
used. In addition to commercial
Switches or potentiometers for detecting the angle of rotation
increasingly magnetic field sensors used. These include a variety
of Hall elements and generate in operation in a magnetic field
signal called Hall voltage. The Hall voltage is here
proportional to the product of the vertical component of the magnetic
Flux density and the Hall current. From a spatial arrangement of several
Hall elements can be
the vector of the magnetic flux density and thus the angle of rotation
a precise detection of the angle of rotation can further the knowledge
the absolute size of the magnetic
Flux density be appropriate.
From this conclusions about the
Signal / noise ratio
the measured signal and thus the accuracy of the determined
Pull the angle of rotation.
It is the object of the present invention to provide a sensor evaluation device
indicate that the accuracy is increased. Furthermore, it is one
Object of the invention, a method for operating a sensor arrangement
to provide with the improved accuracy of the sensor assembly
Tasks become with the objects
the independent one
1 and 11 solved.
Developments and advantageous embodiments of the invention result
from the dependent claims.
the proposed principle contains the
Sensor evaluation arrangement a sensor for generating a sensor signal
as well as a connected controllable supply device for
Supply of the sensor and control of the sensor signal amplitude.
It is an evaluation device for generating a first evaluation signal
provided from the sensor signal. Furthermore, the inventive evaluation arrangement contains
a recycling device
for generating a second evaluation signal from the sensor signal.
The first and the second evaluation signal is sent to a control device
issued to control the supply device in dependence
is formed of the first and second evaluation signal.
Advantage is thereby the supply of the sensor with the controllable
Supply device regulated such that the sensor with as possible
constant sensitivity (constant signal / noise ratio).
This is inventively characterized
achieved that from the sensor signal emitted by the sensor different
Evaluation signals are determined. These can be in an evaluation device
link to a result,
which is a measure of the sensitivity
indicates the sensor. With the help of the inventive arrangement are therefore a
Power-efficient evaluation of the sensor signal and thus a
Accuracy in the evaluation of the sensor signal possible. Especially
is achieved by the common evaluation that a mistake in
an evaluation signal due to the signal processing performed by
the second evaluation signal can be corrected.
According to an embodiment of the invention, the sensor comprises a Hall element arrangement
for detecting a magnetic field. This may be preferred to
Output of a sensor signal to be formed with two components.
The two components of the sensor signal can turn completely
of the sensor are substantially perpendicular to each other. By a
appropriate evaluation leaves
the feedback device and
the connected control device generate a control signal.
In an embodiment of the invention the feedback means comprises means for outputting a control signal from the sensor signal, the control signal corresponding to a rotation angle of the sensor with respect to a reference plane. The device is thus designed to determine an angle of the sensor relative to a plane.
a development of the invention is the first evaluation signal
the sum of the absolute values of two substantially to each other
derived perpendicular components. In one embodiment
this embodiment contains
the Sensorauswerteschaltung this rectifier elements, the output side
are connected to a summator.
the method according to the invention
for operating a sensor arrangement, the output from a sensor
Detected sensor signal and determines therefrom a first and a second evaluation signal.
To supply the sensor is now from the first and second evaluation signal
generates a control signal, by means of which the supply of the sensor
is controlled. In other words, a control becomes the supply
of the sensor thus not derived by an evaluation signal
generated the emitted sensor signal, but over several evaluation signals.
These evaluation signals can
advantageously represent different parameters of the sensor signal.
This will make it possible over the
Control of the supply a correction of the sensor signal to the effect
make sure that these are for
a later one
Signal Processing has required accuracy.
In one embodiment of the invention, the sensor signal in
Shape of a sinusoidal component
and a cosinusoidal component substantially perpendicular thereto.
These two components can
be processed so that the result is a measure of a
Angle of the sensor with respect to
represents a predetermined level. Likewise, the two components can be left
rectify individually and add their amplitudes. The two so
resulting evaluation signals can
be further processed and, for example, by the rectification
and compensate for the fluctuation generated.
as well as the method are particularly suitable for non-contact
Use to determine angles of rotation. At the same time can through
the intended feedback
and the processing of two evaluation signals a "push" or "pull function" regardless of
Realize absolute value.
Invention will be described below with reference to embodiments and drawings
explained in detail.
The figures shown serve solely to illustrate the
Invention and are therefore only schematic and not to scale
executed. functionally identical
Components carry the same reference numerals.
1 An embodiment of the sensor arrangement according to the invention,
2 a first example of application for the sensor arrangement according to the invention,
3 a second application example of the sensor arrangement,
4 an amplitude / angle diagram for illustrating the evaluation signal as a function of the components of the sensor signal,
5 an amplitude angle diagram with various signals to illustrate the invention.
1 shows a possible embodiment of a sensor arrangement according to the invention. In this embodiment, the sensor comprises a Hall element arrangement for determining a rotation angle. In Hall elements, the generated Hall voltage is proportional to the product of the vertical component of a magnetic field vector B passing through the element and the Hall current I. Thus, at a constant Hall current, the change in the vertical component of a magnetic field, for example, due to a rotation of the magnetic field or a change in amplitude Magnetic field can be determined. By the term rotation angle is meant the angle enclosed by a plane in which the Hall elements lie and a reference plane. In the following, the reference plane is the plane that is perpendicular to a magnetic field vector, so that when both planes are parallel, the Hall voltage assumes its maximum value.
To determine the absolute rotation angle, the in 1 illustrated sensor arrangement 10 a total of eight Hall elements 103 and is designed to detect a rotation angle. The perpendicular through the Hall elements component of the magnetic field is represented by a single circle with a cross. The hall elements 103 be from a Hall voltage I BIAS at an input 101 provided. The elements are aligned so that the sensor signal they produce has two distinct components, referred to as "sine" and "cosine" channels. In the present case, with a complete rotation of the sensor in the magnetic field, the first component has a sinusoidal course, while the second component of the Sen sorsignals has a cosinusoidal course. Thus, the components have a phase shift of substantially 90 Degree to each other.
The two components are in an amplifier arrangement 2 by means of two amplifiers 22 and 23 amplified and output as measuring signal MS1, MS2. The output of the respective amplifier 22 . 23 is connected to the input terminal of a rectifier stage 5 guided. The rectifier stage 5 may for example be designed as a simple diode rectifier and generates from the two measured components MS1 and MS2 each rectified signal. The outputs of the rectifier 5 are at the input of an adder 6 connected. With the arrangement of rectifier 5 and adder 6 the absolute values of the two components MS1, MS2 are determined and added to a total signal. This represents the first evaluation signal AS.
As is apparent from the above the adder 6 standing diagram, the rectified components depend on the angle of rotation of the sensor 10 a periodically changing amplitude between two extreme values. The entire output signal AS is now a control input 72 an automatic control loop 7 fed. The control device 7 includes a control output 73 , with the utility 4 for the Hall sensor 10 is coupled. About this control output gives the control device 7 a control signal CS to the supply device 4 from. This regulates the Hall current I BIAS for the individual Hall elements.
Through this control loop, it is possible to set the Hall current I BIAS so that the sensor signal generated by the sensor with its two components MS1 and MS2 has a good signal / noise ratio. As a result, the accuracy can be increased in a rotation angle measurement. In addition, "push" or "pull functions" can be realized in which the magnetic field is artificially amplified or reduced in its amplitude. This is a push button 8th provided with the utility 4 is coupled. By pressing the button 8th the Hall current I BIAS is changed and thus generates an approximately jump-like change in the amplitude of the sensor signal.
Alternatively, a "push" or "pull" function can be realized by using the push button 8th the distance between the sensor 10 and not shown, the magnetic field generating element is changed. With a constant angle of rotation thereby also changed the amplitude of the total signal from the two components MS1 and MS2 and the function is detected.
In the evaluation available here in the rectifiers 5 and the adder 6 However, an evaluation signal AS is generated, which is over a full 360 degree rotation of the sensor 10 is not constant, but has a relatively large fluctuation of about 30% around an average. A control signal CS generated solely from the evaluation signal AS also leads to a periodic change in the Hall current I BIAS supplied to the sensor and thus a reduction in the accuracy or a deterioration of the signal / noise ratio of the sensor signal.
Improvement is proposed according to the invention,
in addition to the first evaluation signal, a second evaluation signal
to generate a different evaluation of the two components and this
for correction or compensation of the amplitude fluctuations
to use the first evaluation signal. This can be done
generate a correction signal, thereby optimizing the adjustment
the Hall current possible
is. In the present case, an angle-dependent reference signal is used as the second evaluation signal RS,
that is a measure of the current
represents adjacent angle of rotation. This is especially good
for correction, since the amplitude fluctuation of the first evaluation signal
a periodic dependence of
Has angle of rotation.
For this purpose the two component signals MS1 and MS2 are applied to the inputs 31 respectively 32 an interpolator 3 created. The interpolator 3 is designed to determine the angle of rotation using the two components MS1 and MS2. This is possible because, due to the phase offset of 90 degrees between the two components, an unambiguous determination of the angle by evaluation of the amplitudes of the two component signals is possible. In detail, he combines the values of the two components MS1, MS2 with each other and receives a result value that corresponds to a defined rotation angle.
The output side is the interpolator 3 to an angle decoder 9 connected. This generates from the interpolator 3 emitted signal a digital signal, which is a measure of the respective angle. The output of the angle decoder 9 is connected to a control terminal of a controllable reference voltage source 90 connected. This generates a reference voltage depending on the value output by the angle decoder and leads this as reference signal RS to a second input 71 the control circuit 7 to.
Since the angle-dependent profile of the first evaluation signal AS due to the special arrangement of the sensor 10 is known, can be with the angle evaluation in the angle decoder 9 a suitable Select the net reference signal to correct the amplitude deviation in the first evaluation signal. The diagram above the angle decoder schematically shows the values of the reference voltages as a function of the angle of rotation. It can be seen that the angle-dependent values of the voltages have a similar course as the first evaluation signal. The profile of the second evaluation signal RS follows the course of the first evaluation signal AS via the angle. By a higher accuracy in the evaluation of the angle decoder 9 it's even easier to visualize and improve the accuracy of the correction.
thus becomes inherent in the properties of the sensor
Relationship used to from the sensor signal, respectively the two components
a feedback signal
to win. Thus, an error correction of the main control signal is performed
in the present case represents the first evaluation signal AS. The relationship
is predetermined and can be, for example, the physics of
Measurement process and be dependent on the geometric dimensions of the sensor.
4 shows an amplitude-angle diagram for the two components MS1, MS2 of the sensor signal, the first evaluation signal AS and the second evaluation signal RS of the feedback device 9a over a full turn of the sensor 10 , The angle of rotation is here not in angular notation but shown as a digital 8-bit-valued signal. For example, the digital value 128 corresponds to an angle of 180 °.
It can be seen that the first component MS1 represents a single sinusoid over the entire angle of rotation. To this end, shifted by 90 ° in phase, the second component MS2 is shown as a cosine signal. The sum of the absolute values of the two signals yields the first evaluation signal AS. This varies depending on the angle between a minimum value of about 0.75 and a maximum value of about 1.05 of a normalized amplitude. The angle itself can be uniquely determined by evaluating the two component signals MS1 and MS2 with the interpolator 3 determine. The result of the interpolator is used with the angle decoder 9 and the reference voltage source 90 a value discrete second evaluation signal RS determined. This assumes as shown different different values, so as to approximate the course of the evaluation signal AS approximately. In the control device 7 the difference between the first evaluation signal AS and the two th evaluation signal RS to generate the control signal CS is formed.
5 shows an enlarged section including the corrected control signal CS.
The ordinate shows in the diagram of the 5 the normalized level for the control signal. For the evaluation signal AS, it can be seen that the normalized level varies as a function of the angle by approximately 30%. A control of the supply device 4 according to 1 With a control signal CS formed solely from the first evaluation signal, therefore, a corresponding periodic fluctuation of the Hall current I BIAS would result. As a result, the signal / noise ratio may deteriorate or the sensor may also be overdriven. A lower accuracy in an angle determination by evaluation of the sensor signal would be the result.
of the second evaluation signal RS becomes a corrected control signal
CS generated. This becomes the difference of the first evaluation signal
Derived AS and the second evaluation signal RS. The result fluctuates
the corrected control signal CS generated in this way is angle-dependent low
around the face value. By a higher
Accuracy in the generation of the second evaluation signal RS in
Angle decoder can measure the variation in the corrected control signal CS
be further reduced because the second evaluation signal RS the
Amplitude of the first evaluation signal better emulates.
With the feedback and generation of the second evaluation signal, the angle-dependent measurement is increased in accuracy and realizes the possibility of error-free detection of a "push" or "pull function". For example, as in 1 represented by the push button 8th In addition, the Hall current I BIAS changes this leads to a change in the amplitude of the sensor signal with the two components MS1 and MS2. This change can be detected independently of the rotation angle with the invention.
Two application examples for the sensor arrangement according to the invention show the 2 and 3 , In 3 is the sensor 10 the arrangement around the axis 15 rotatably mounted in a magnetic field. The individual magnetic field lines are essentially parallel in the region of the sensor. By evaluating the sensor signal, the rotational angle α of the sensor relative to a plane perpendicular to the magnetic field can be determined and output as a digital value. The feedback of the evaluation signal and the generation of the corrected control signal according to the invention improves the measurement. As a result, either the Hall current can be reduced or, with the same current, the accuracy of the measurement can be increased.
In the application of the 2 , this is done by a bar magnet 140 Magnetic field changed by the bar magnet 140 around the point 14 is rotated along the Z-direction. The sensor 10 also outputs a signal depending on the direction of rotation. Thus, in the sensor arrangement according to the invention, the direction of rotation and the angle can be determined either absolutely or relative to the previous position. In addition, the distance d of the bar magnet from the sensor 10 be changed. This is possible, inter alia, by a push button. For example, an inclination about an axis perpendicular to the plane or depression would be possible. As a result, the strength of the magnetic field and thus the sensor signal change. The evaluation of both signals and the correction enables the detection of such additional changes independently of a rotation angle.
illustrated invention is natural
not limited to Hall elements for detecting a rotation angle. Of the
Rather, it can also be fed back
Sensor arrangements are extended based on other physical principles
based. The illustrated scheme with the help of several of the
emitted sensor signal generated evaluation signals can be
especially if the information is in two different
Parameters of the sensor signal, for example in the amplitude and
are included in the phase. So can an error in the evaluation
of one parameter corrected by the evaluation of the other parameter
become. The present scheme can be in an analog
Forming control engineering. Likewise is a combination of digital and
analog circuit technology, for example, the generation of the first
and second evaluation signal possible.
- reinforcing device
- control device
- angle decoder
- Return means
- pivot point
- Control signal output
- Reference voltage source
- Sensor signal components
Evaluation signal, reference signal
- control signal