Measuring Device And Measured Quantity Sensor Having Coupled Processing And Excitation Frequencies

• US 20080126015A1
• Filed: 12/08/2006
• Published: 05/29/2008
• Est. Priority Date: 11/24/2006
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Hammerschmidt, Dirk
• Granted Patent: US 7,980,134 B2
• Time in Patent Office: Days
• US Class Current: 702/189
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces

Abstract

A measuring device for determining a measured quantity having an oscillatory structure where an oscillation signal is detectable. The measuring device further includes a device for exciting the oscillatory structure by an excitation frequency to result in an oscillation of an oscillation frequency. The measuring device further has a device for processing the oscillation signal by a frequency depending on the oscillation frequency and the excitation frequency. Furthermore, the measuring device includes an evaluator for determining the measured quantity based on the oscillation signal processed.

Claims

1. A measuring device for determining a measured quantity, comprising:

an oscillatory structure in which an oscillation signal is detectable;

means for exciting the oscillatory structure by an excitation frequency to result in an oscillation with an oscillation frequency;

means for processing the oscillation signal synchronous to the oscillation frequency or the excitation frequency; and

evaluating means for determining the measured quantity based on the processed oscillation signal.

2. The measuring device according to claim 1, wherein the means for processing includes means for sampling an oscillation signal by a sample frequency.

3. The measuring device according to claim 1, wherein the means for processing comprises a filter the filter characteristic of which depends on the oscillation frequency or the excitation frequency.

4. The measuring device according to claim 3, wherein the filter characteristic is determined by an analog device of an impedance which depends on the oscillation frequency or the excitation frequency.

5. The measuring device according to claim 1, wherein the means for exciting comprises means for regulating the excitation frequency, an excitation amplitude or an excitation phase by a feedback branch via which the oscillation of the oscillatory structure is detectable.

6. The measuring device according to claim 5, wherein the oscillatory structure, the means for exciting and the feedback branch form a resonance circuit oscillating at a self-resonance of the oscillatory structure.

7. The measuring device according to claim 1, wherein the means for exciting is formed such that the oscillation of the oscillation frequency is excited, while other oscillation modes of the oscillatory structure basically remain unexcited.

8. The measuring device according to claim 1, wherein the oscillatory structure comprises a mechanical structure capable of oscillating in a first oscillation mode and a second oscillation mode which comprise a coupling depending on the measured quantity, wherein the oscillatory structure is excitable to result in an oscillation in the first oscillation mode by an excitation by the means for exciting by the excitation frequency, and the oscillatory structure is coupled to the means for processing such that a signal resulting from the oscillation of the mechanical structure in the second oscillation mode is available for the means for processing as a detectable oscillation signal.

9. The measuring device according to claim 8, wherein the evaluating means comprises force-feedback means for counteracting the oscillation of the mechanical structure in the second oscillation mode depending on the oscillation signal available, and the evaluating means, when determining the measured quantity, makes the determination in dependence on the counteracting degree.

10. The measuring device according to claim 8, wherein the means for exciting comprises means for regulating the excitation amplitude, frequency or phase by a feedback branch by which a feedback signal is detectable which results from the oscillation of the mechanical structure in the first oscillation mode, wherein another sampling means for sampling the feedback signal by another sample frequency which depends on the excitation frequency is connected into the feedback branch.

11. The measuring device according to claim 10, wherein a first digital filter for filtering the sampled feedback signal is connected into the feedback branch.

12. The measuring device according to claim 1, wherein the evaluating means comprises a second digital filter for filtering the oscillation signal available or sampled.

13. The measuring device according to claim 11, wherein the digital filter is operated by a clock frequency derived from one of the oscillation frequencies.

14. The measuring device according to claim 1, wherein the measured quantity corresponds to a rotational rate of a rotation of the measuring device.

15. The measuring device according to claim 2, further comprising means for establishing a fixed clock ratio between the sample frequency on the one hand and the excitation frequency or oscillation frequency on the other hand.

16. A measured quantity sensor comprising:

an oscillatory structure comprising a first detection terminal at which an oscillation signal is detectable, and an excitation terminal, wherein the oscillatory structure is excitable to result in an oscillation with an oscillation frequency by applying an excitation signal with an excitation frequency to the excitation terminal;

an excitation circuit comprising an output coupled to the excitation terminal;

a signal processor comprising an input coupled to the first detection terminal, a frequency input to which a signal of a frequency which depends on the oscillation frequency of the oscillatory structure or the excitation frequency at the excitation terminal may be applied, and an output; and

an evaluation circuit comprising an input coupled to the output of the signal processor, and an output representing a measured quantity sensor output of the measured quantity sensor.

17. The measured quantity sensor according to claim 16, wherein the signal processor comprises a sampler comprising a sample frequency input coupled to the frequency input.

18. The measured quantity sensor according to claim 16, wherein the signal processor additionally comprises a filter the filter characteristic of which depends on the oscillation frequency or the excitation frequency.

19. The measured quantity sensor according to claim 18, wherein the filter characteristic is determined by an analog device of an impedance which depends on the oscillation frequency or the excitation frequency.

20. The measured quantity sensor according to claim 16, wherein the excitation circuit forms a control loop for regulating the excitation frequency, an excitation amplitude or an excitation phase with a feedback branch, via which the oscillation of the oscillatory structure is detectable.

21. The measured quantity sensor according to claim 16, wherein the oscillatory structure comprises a mechanical structure capable of oscillating in a first oscillation mode and a second oscillation mode which comprise a coupling which depends on a measured quantity of the measured quantity sensor to be measured, wherein the mechanical structure is excitable to result in an oscillation in the first oscillation mode by applying the excitation signal to the excitation terminal, and a signal which results from an oscillation of the mechanical structure in the second oscillation mode is detectable as the oscillation signal at the first detection terminal.

22. The measured quantity sensor according to claim 21, wherein the evaluation circuit comprises a force-feedback circuit and the oscillatory structure additionally comprises a force-feedback terminal where the oscillation of the mechanical structure in the second oscillation mode can be counteracted, wherein the force-feedback circuit is connected between the output of the signal processor and the terminal of the evaluation circuit and comprises an output coupled to the force-feedback terminal.

23. The measured quantity sensor according to claim 21, wherein the excitation circuit forms a control loop with a feedback branch and the oscillatory structure additionally comprises a second detection terminal where the oscillation of the mechanical structure in the first oscillation mode is detectable, wherein the feedback branch is coupled to the second detection terminal and another sampler comprising a sample frequency input is connected therein, to which a signal of a frequency which depends on the excitation frequency at the excitation terminal may be applied.

24. The measured quantity sensor according to claim 23, wherein the control loop for controlling the force feedback is formed such that modes other than one of the desired oscillation modes of the mechanical structure are suppressed or basically remain unexcited.

25. The measured quantity sensor according to claim 23, wherein a digital filter is connected into the feedback branch downstream of the further sampler.

26. The measured quantity sensor according to claim 16, wherein the evaluation circuit comprises a digital filter comprising an input coupled to the output of the signal processor.

27. The measured quantity sensor according to claim 16, wherein the evaluation circuit is operated by a clock derived from one of the oscillation frequencies.

28. The measured quantity sensor according to claim 16, wherein the measured quantity corresponds to a rate of rotation of a rotation of the measured quantity sensor.

29. The measured quantity sensor according to claim 17, further comprising a clock multiplier comprising an input and an output by which it is connected between the excitation circuit on the input side and the sampler on the output side such that a sample frequency at the sample frequency input comprises a fixed clock ratio to the excitation frequency or the oscillation frequency.

30. A measured quantity sensor, comprising:

a mechanical structure capable of oscillating in a first oscillation mode and a second oscillation mode which comprises a coupling which depends on a measured quantity of the measured quantity sensor to be measured;

a first excitation terminal at which an oscillation of the mechanical structure with an oscillation frequency in the first oscillation mode is excitable by exciting it by an excitation frequency;

a first detection terminal at which an oscillation of the mechanical structure in the second oscillation mode is detectable;

a second detection terminal at which the oscillation of the mechanical structure in the first oscillation mode is detectable;

an excitation circuit comprising an output coupled to the first excitation terminal, wherein the excitation circuit forms a control loop with a feedback branch coupled to the second detection terminal;

a signal processor comprising an input coupled to the first detection terminal, a frequency input coupled to a circuit part of the excitation circuit where the excitation frequency at the first excitation terminal is detectable or to the second detection terminal, and an output; and

an evaluation circuit comprising an input coupled to the output of the signal processor, and an output representing a measured quantity sensor output of the measured quantity sensor.

31. The measured quantity sensor according to claim 30, wherein the signal processor comprises a sampler comprising a sample frequency input coupled to the frequency input.

32. The measured quantity sensor according to claim 30, wherein the signal processor comprises a filter the filter characteristic of which depends on the oscillation frequency or the excitation frequency.

33. The measured quantity sensor according to claim 32, wherein the filter characteristic is determined by an analog device of an impedance which depends on the oscillation frequency or the excitation frequency.

34. The measured quantity sensor according to claim 30, wherein the evaluation circuit comprises a force-feedback circuit, wherein the measured quantity sensor additionally comprises a second excitation terminal where the oscillation of the mechanical structure in the second oscillation mode can be counteracted, wherein the force-feedback circuit is connected between the output of the sampler and the input of the evaluation circuit and comprises an output coupled to the second excitation terminal.

35. The measured quantity sensor according to claim 31, wherein another sampler is connected into the feedback branch of the control loop of the excitation circuit the sample frequency input of which is coupled to the circuit part of the excitation circuit where the excitation frequency is detectable.

36. The measured quantity sensor according to claim 35, wherein a digital filter is connected into the feedback branch of the control loop of the excitation circuit downstream of the further sampler.

37. The measured quantity sensor according to claim 30, wherein the evaluation circuit comprises a digital filter comprising an input coupled to the output of the signal processor.

38. The measured quantity sensor according to claim 30, wherein the measured quantity corresponds to a rate of rotation of a rotation of the measured quantity sensor.

39. The measured quantity sensor according to claim 30, further comprising a clock multiplier comprising an input and an output by which it is connected between the excitation circuit on the input side and the signal processor on the output side such that a frequency at the frequency input comprises a fixed clock ratio to the excitation frequency at the first excitation terminal or the oscillation frequency.

40. A method for determining a measured quantity by means of an oscillatory structure, comprising:

exciting the oscillatory structure by an excitation frequency to result in an oscillation with an oscillation frequency;

detecting an oscillation signal at the oscillatory structure;

processing the oscillation signal by a frequency which depends on the oscillation frequency or the excitation frequency; and

determining the measured quantity based on the oscillation signal processed.

41. The method according to claim 40, wherein the step of processing includes a step of sampling by a sample frequency which depends on the oscillation frequency or the excitation frequency.

42. The method according to claim 40, wherein the step of processing includes a step of filtering by a filter characteristic, the filter characteristic depending on the oscillation frequency or the excitation frequency.

43. The method according to claim 42, wherein the step of filtering further includes a step of adjusting an impedance of an analog device in dependence on the oscillation frequency or the excitation frequency to determine the filter characteristic.

44. The method according to claim 40, wherein exciting comprises regulating the excitation frequency, an excitation amplitude or an excitation phase by means of a feedback branch via which the oscillation of the oscillatory structure is detectable.

45. The method according to claim 41, wherein the oscillatory structure comprises a mechanical structure capable of oscillating in a first oscillation mode and a second oscillation mode which comprise a coupling depending on the measured quantity, wherein exciting the oscillatory structure comprises exciting the oscillatory structure by an excitation frequency to result in an oscillation in the first oscillation mode, and sampling comprises sampling a signal as the detectable oscillation signal resulting from an oscillation of the mechanical structure in the second oscillation mode.

46. The method according to claim 45, wherein determining comprises counteracting the oscillation of the mechanical structure in the second oscillation mode depending on the oscillation signal sampled, and determining the measured quantity depending on the counteracting degree.

47. The method according to claim 45, wherein exciting comprises regulating the excitation frequency by means of a feedback branch via which a feedback signal is detectable resulting from the oscillation of the mechanical structure in the first oscillation mode, and the method further comprising sampling the feedback signal by another sample frequency depending on the excitation frequency.

48. The method according to claim 47, further comprising digital filtering of the sampled feedback signal.

49. The method according to claim 41, further comprising digital filtering of the sampled oscillation signal.

50. The method according to claim 40, wherein the measured quantity corresponds to a rate of rotation of a rotation of the measuring device.

51. The method according to claim 41, further comprising establishing a fixed clock ratio between the sample frequency on the one hand and the excitation frequency or the oscillation frequency on the other hand.

52. A measuring method comprising:

exciting a mechanical structure capable of oscillating in a first oscillation mode and a second oscillation mode which comprise a coupling depending on a measured quantity to be measured, by an excitation frequency to result in an oscillation of the mechanical structure of an oscillation frequency in the first oscillation mode;

detecting an oscillation of the mechanical structure in the second oscillation mode;

detecting the oscillation of the mechanical structure in the first oscillation mode;

regulating the excitation frequency, an excitation amplitude or an excitation phase depending on the detected oscillation of the mechanical structure in the first oscillation mode;

processing the detected oscillation of the mechanical structure in the second oscillation mode by a frequency depending on the excitation frequency or the oscillation frequency of the oscillation in the first oscillation mode; and

determining the measured quantity to be measured on the basis of the processed oscillation of the mechanical structure in the second oscillation mode.

53. The measuring method according to claim 52, wherein the step of processing includes a step of sampling the detected oscillation of the mechanical structure in the second oscillation mode by a sample frequency depending on the excitation frequency or the oscillation frequency of the oscillation in the first oscillation mode.

54. A computer program product comprising a program code on a computer-readable medium, the program code when executed on a computer or microcontroller performing a method for determining a measured quantity by means of an oscillatory structure, comprising:

exciting the oscillatory structure by an excitation frequency to result in an oscillation of an oscillation frequency;

detecting an oscillation signal at the oscillatory structure;

processing the oscillation signal by a frequency which depends on the oscillation frequency or the excitation frequency; and

determining the measured quantity based on the oscillation signal processed.

55. A computer program product comprising a program code on a computer-readable medium, the program code when executed on a computer or microcontroller performing a measuring method comprising:

exciting a mechanical structure capable of oscillating in a first oscillation mode and a second oscillation mode which comprise a coupling depending on a measured quantity to be measured, by an excitation frequency to result in an oscillation of the mechanical structure of an oscillation frequency in the first oscillation mode;

detecting an oscillation of the mechanical structure in the second oscillation mode;

detecting the oscillation of the mechanical structure in the first oscillation mode;

regulating the excitation frequency, an excitation amplitude or an excitation phase depending on the detected oscillation of the mechanical structure in the first oscillation mode;

processing the detected oscillation of the mechanical structure in the second oscillation mode by a frequency depending on the excitation frequency or the oscillation frequency of the oscillation in the first oscillation mode; and

determining the measured quantity to be measured on the basis of the processed oscillation of the mechanical structure in the second oscillation mode.