Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
  • G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
  • G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
  • G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
  • G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
  • G01C19/5776—Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719

Definitions

• the invention relates to a device for measuring a rotation rate, comprising a mechanical rotation rate sensor having an inertial mass, which is displaceable by means of an excitation means along a primary axis in a primary vibration and along a transverse to the primary axis secondary axis is deflectable such that they occur when a rotation rate a secondary axis excited by the Coriolis force passes through a sensitive axis extending transversely to the primary axis and transverse to the secondary axis along the secondary axis, with at least one sensor element for detecting an amplitude-modulated sensor signal for the secondary oscillation, with a sigma-delta modulator having a sigma-delta modulator Sensor element associated low-pass filter, a quantizer downstream of this and a arranged in a feedback path secondary actuator by means of which a Coriolis force counteracting force is exerted on the mass, the second , Raktor is connected in such a way over the remindplungspfdd to the quantizer that
• Such a device is known in practice. It is used, for example, in driver assistance systems of motor vehicles, in electronic devices which decelerate individual wheels to stabilize the driving state of a motor vehicle or in navigation systems.
• the rotation rate sensor of the device has an inertial mass, which is constantly displaced by means of an excitation device relative to a holder in a primary vibration. The mass is suspended in such a way that upon the occurrence of a rate of rotation about a sensitive axis extending orthogonally to the axis of the primary oscillation it is excited by the Coriolis force to a secondary oscillation.
• the axis of the secondary vibration is aligned orthogonal to the primary vibration and orthogonal to the sensitive axis.
• the secondary oscillation is measured by means of a sensor element and converted into a corresponding analog electrical sensor signal. Since the mass to
• the sensor signal is an amplitude modulated signal.
• the carrier frequency of this signal corresponds to the frequency of the primary oscillation.
• the analog sensor signal is digitized using a sigma-delta modulator.
• the output signal of the sigma-delta delta modulator is thus a binary signal with a high clock frequency, a so-called bitstream.
• this leads to a high quantization error or a strong quantization noise the integration behavior of the sigma-delta modulator leads to the so-called noise-shaping eflect, which spectrally shapes the noise and largely separates it from the signal. Mt the lowass
• the quantization noise can be very effectively suppressed.
• the device has a secondary reactor; by means of which between the mass and the holder a force can be applied, which counteracts the Coriolis force.
• the secondary reactor is connected to the quantizer via a feedback path such that a feedback signal from the quantizer compensates for the secondary oscillation over the time average.
• the binary bitstream is used. This means that the mass-acting Coriolis force is almost completely compensated. This also increases the noise immunity and ultimately the resolution of the rotation rate signal.
• the device has the disadvantage that the sampling frequency of the quantizer must be very high due to the low-pass filter, because now the signal band to be scanned is broadened.
• the signal band is not only a small range and the frequency of the primary vibration around but ranges from the baseband to the amplitude-modulated yaw rate signal. Usually, the sampling frequency is about one hundred times the frequency of the primary vibration. The device therefore has a correspondingly high energy consumption
• the sampling frequency of the quantizer can be reduced by using a bandpass as a loop filter instead of the low-pass filter.
• the operational amplifiers used In order to generate the necessary steepness of the transfer function of the bandpass filter, the operational amplifiers used must have a high gain in the signal band, so that they still work reliably at the input signal frequency. Due to the high gain, however, there is also a high energy consumption.
• the comparator is operated at a sampling frequency which usually corresponds to 4-8 times the resonant frequency of the mechanical sensor. This additionally increases energy consumption.
• a first modulation stage is arranged for shifting the frequency band of the amplitude-modulated sensor signal into a lower frequency range between the sensor element and the low-pass filter
• a second modulation stage is arranged for reversing the frequency shift in the feedback path between the quantizer and the yaw rate sensor.
• this makes it possible to operate the quantizer with a relatively low sampling rate, but nevertheless to provide a low-pass filter as a loop filter.
• the device can be operated energy saving. Due to the compensation of the Coriolis force caused by the feedback path, a high linearity and bandwidth of the rotation rate measurement signal are made possible.
• the rotation rate measurement signal is largely independent of temperature influences.
• the rotation rate sensor can be designed as a tuning fork gyroscope.
• a gyroscope is known from Ajit Sharma et al .: A High-Q In-Plane SOI Tuning Fork Gyroscope, IEEE (2004), pages 467-470.
• the rotation rate sensor can also have a primary mass and a secondary mass, the latter forming the inertial mass.
• the primary mass is arranged deflectable on the i o bracket along a primary axis.
• the secondary mass is suspended in such a way that it can be deflected orthogonally to the primary axis along a secondary axis relative to the primary axis.
• the arrangement formed by the primary and the secondary mass is in driving connection with an excitation device, by means of which the arrangement along the primary
• the first modulation stage has a first input connected to a sensor signal output of the sensor element and a second connected to a signal generator
• the second modulation stage has a first input connected to an output of the quantizer and a second input connected to the signal generator, and wherein the signal generator is designed to generate a drive signal having at least one sinusoidal component.
• Modulation signal are thus modulated in their associated modulation stage in each case with the sinusoidal component of the drive signal or m ulti pli instance. Because of this, the sensor signal and the vertical delta modulation signal can each be shifted energy-savingly into another frequency band.
• the excitation device for generating the primary oscillation has a primary actuator which is in driving connection with the mass, and if the primary reactor is synchronized with the sinusoidal signal generator.
• the same sinusoidal signal can be used to drive the primary actuator and operate the 35 modulation stages.
• the sigma-delta modulator has a sampling device which is synchronized with the signal generator.
• the drive signal provided by the sine signal generator can also be used for clocking the sampling device.
• FIG. 1 shows a control circuit equivalent circuit diagram of a device for measuring a rotation rate, which has an electromechanical sigma-delta modulator, and
• FIG. 2 shows an example of the power density spectrum of a sigma-delta-modulated yaw rate signal measured by the device
• a device 1 for measuring a rate of rotation has a mechanical rotation rate sensor 2, which is shown only schematically in the drawing, and has a primary mass which is deflectably arranged on a holder along a primary axis.
• An inert secondary mass is suspended on the primary mass in such a way that it can be deflected orthogonally to the primary axis along a secondary axis relative to the primary axis.
• the primary mass is in drive connection with an excitation device, by means of which the arrangement consisting of the primary mass and the secondary mass can be moved back and forth parallel to the primary axis.
• an excitation device for generating a sinusoidal component having a drive signal for the excitation device, this has a sine signal generator 3.
• the primary oscillation generated by means of the excitation means has a constant amplitude and a constant frequency The frequency of the primary oscillation substantially coincides with the resonant frequency of the arrangement.
• a sensor element 4 which has at least one first electrode arranged on the primary mass and at least one second electrode arranged on the secondary mass, an electrical sensor signal dependent on the secondary oscillation is detected. Since the primary mass must be excited to the primary vibration to detect the sensor signal, the sensor signal is amplitude modulated. The carrier frequency of the sensor signal coincides with that of the frequency of the primary vibration.
• a sensor signal output of the sensor element 4 is connected to a first input of a first modulation stage 5.
• a second input of the first modulation stage 5 is connected to the output of the sinusoidal signal generator 3.
• the rotation rate signal is modulated into the baseband.
• the correspondingly modulated analog rotation rate signal is output at an output of the first modulation stage 5.
• This output is connected to an input of a third-order analog low-pass filter 6.
• the signal is amplified and the quantization noise is suppressed and thus advantageously formed from the baseband.
• the low-pass filter 6 has the following Laplace transform
• An output of the analog low-pass filter ⁇ is connected to a first comparator input of a comparator 7 serving as a 1-bit analog-to-digital converter or quantizer.
• a second, not shown in detail in the drawing input the comparator is at a predetermined electrical potential.
• the compati- rator 7 has a scanning device not illustrated in the drawing, which samples the signal at the first comparator input modulated signal syn ⁇ chron to the sinusoidal drive signal of the sine wave generator. 3
• the sampling device has for this purpose a clock signal input which is connected to the sine signal generator 3.
• the sigma-delta modulation signal generated by comparing the sampled signal with the predetermined electric potential is output in the form of a bit stream.
• the output 8 of the comparator 7 is connected via a feedback path to a first input of a second modulation stage 9.
• a second input of the second modulation stage 9 is connected to the output of the sinusoidal signal generator 3.
• the sigma-delta modulation signal is highly modulated to the input frequency.
• the signal thus obtained is amplified to drive a secondary reactor 10 located in the feedback path.
• the latter applies a force between the primary mass and the secondary mass, which counteracts the Coriolis force F c , as a function of the sigma-delta modulation signal highly modulated onto the input frequency.
• this is shown schematically by an adder 1 1.
• the displacement of the primary mass is compensated in the time average.
• the device therefore has a closed electromechanical control loop for processing the rotation rate signal
• FIG. 2 shows graphically an example of the power density spectrum of a sigma-delta modulation signal applied to the output 8 of the comparator 7.
• the typical noise-shaping behavior of the sigma-delta converter is clearly recognizable, in which the resonance almost completely disappears.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Signal Processing (AREA)
• Gyroscopes (AREA)
• Pressure Sensors (AREA)

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• 2010
  • 2010-12-02 DE DE102010053022.0A patent/DE102010053022B4/de active Active
• 2011
  • 2011-12-01 WO PCT/EP2011/006018 patent/WO2012072255A1/de active Application Filing
  • 2011-12-01 JP JP2013541247A patent/JP2013545986A/ja active Pending
  • 2011-12-01 EP EP11794031.2A patent/EP2646774A1/de not_active Withdrawn
  • 2011-12-01 US US13/990,583 patent/US20140060185A1/en not_active Abandoned
  • 2011-12-01 CN CN2011800660608A patent/CN103339471A/zh active Pending

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