摘要:
In comb drive vibratory gyroscopes, drive-induced Coriolis accelerometer offset is effectively canceled by demodulating the output during equal times of in-phase and anti-phase drive of the shuttle with respect to the velocity signal used for angular rate demodulation. This reduces or eliminates the corresponding thermal and die-stress effects otherwise needing calibration.
摘要:
In a micromachined devices having a movable shuttle driven in oscillation, measuring the electrical charge accumulated on opposing drive capacitors to determine the displacement of the movable shuttle. Alternately, in such a micromachined device, measuring the electrical charge accumulated on a drive capacitor and comparing the measured electrical charge to a nominal electrical charge to determine the displacement of the movable shuttle.
摘要:
Error sources relating to the drive signal applied to the resonator of an inertial sensor, such as in-phase offset errors relating to the drive signal and/or electronic pass-through of the drive signal to accelerometer sense electronics, are detected by modulating the drive signal and sensing accelerometer signals that are induced by the modulated drive signal. Error sources related to aerodynamics of an inertial sensor resonator are detected by modulating the distance between the resonator and the underlying substrate and sensing accelerometer signals that are induced by such modulation. Compensating signals may be provided to substantially cancel errors caused by such error sources.
摘要:
An analog-to-digital converter includes a delta circuit, a sigma circuit, and a quantizer circuit and further includes a feedback circuit that modulates a reference voltage provided to the quantizer circuit based on the quantizer circuit output. Modulation of the quantizer reference voltage dithers the quantizer circuit to effectively reduce or avoid lock bands. The analog-to-digital converter may be used in combination with a microelectromechanical (MEMS) device such as a gyroscope, an accelerometer, or a pressure sensor.
摘要:
A method and device for self-test of a sensor. The method includes stimulating the sensor with signals that generate sensor outputs at a frequency that differs from the frequency of expected sensed parameter signals. The sensor output is filtered to remove the effects of the stimulation inputs, generating a sensed parameter signal. The unfiltered sensor output is compared to the expected output of the sensor with the stimulus input. A malfunctioning sensor may be detected by the comparison and appropriate action may then be taken.
摘要:
A six degree-of-freedom micro-machined multi-sensor that provides 3-axes of acceleration sensing, and 3-axes of angular rate sensing, in a single multi-sensor device. The six degree-of-freedom multi-sensor device includes a first multi-sensor substructure providing 2-axes of acceleration sensing and 1-axis of angular rate sensing, and a second multi-sensor substructure providing a third axis of acceleration sensing, and second and third axes of angular rate sensing. The first and second multi-sensor substructures are implemented on respective substrates within the six degree-of-freedom multi-sensor device.
摘要:
A micromachined device has two suspended masses positioned near each other, each of the masses being dithered along a dither axis. Two couplings, each including an arcuate member and an anchored support beam, are provided between the masses to allow relative anti-phase movement and to resist relative in-phase movement. The coupling extends around a region intermediate the masses where a dither detection device is disposed.
摘要:
Analog-to-digital converters are subject to errors including the known half least significant bit quantization error and also bit weighting errors due to lack of an ideal binary relationship between the transition points of all the bits. The known statistical average error reduction method in which a relatively small dither component is added to the analog input signal can only fractionally reduce overall error and has little effect on bit weighting errors. Herein the analog signal is added to a dither signal, for example a ramp signal, which varies through half the peak to peak digitization range of the converter so that irrespective of the input signal all output signal bits, other than the most significant bit, are "on" for one half of the sampling period. The result is that all the less significant bit errors are cancelled leaving only the easily compensated most significant bit error. A random component can be added to the dither signal to reduce the quantization error.
摘要:
In a multiple axis ring laser gyroscope in which one or more of the laser cavity corner mirrors is or are shared by different cavities and in which the laser beams in these different cavities operate at the same nominal frequency, scattering of the beam in one cavity into another cavity by the shared mirror(s) may produce disadvantageous lock-in effects. To at least lessen this possibility, the frequencies of the beams in the gyroscope disclosed herein are offset one from another, the offset being sufficient to affect lock in but not so great that the frequency of any beam is overly far from the lasing medium gain curve center. The frequency offsets may be produced by introducing offset bias signals into some channels of the gyroscope path length control servosystem.
摘要:
Detection means comprise at least three photodiodes 1, 2 and 3 which are spaced so as to expand to half a wavelength of an interference waveform produced in a ring laser gyroscope. The three photodiodes 1, 2 and 3 produce respective currents A, B and C the magnitudes of which are detected to sense the magnitude and direction of the movement of the interference waveform. The currents A, B and C are fed to a current mirror configured as a Norton amplifier input state 4, the latter producing signals which are fed to logic circuitry for obtaining signals representative of the rate and direction of the movement of the interference waveform.