This disclosure describes techniques of configuring capacitive comb fingers of an accelerometer resonator into discreet electrodes with drive electrodes and at least two sense electrodes. The routing of electrical signals is configured to produce parasitic feedthrough capacitances that are approximately equal. The sense electrodes may be placed on opposite sides of the moving resonator beams such that the changes in capacitance with respect to displacement (e.g. dC/dx) are approximately equal in magnitude and opposite in sign. The arrangement may result in sense currents that are also opposite in sign and result in feedthrough currents of the same sign. The sense outputs from the resonators may be connected to a differential amplifier, such that the difference in output currents may mitigate the effect of the feedthrough currents and cancel parasitic feedthrough capacitance. Parasitic feedthrough capacitance may cause increased accelerometer noise and reduced bias stability.

The disclosure describes techniques to damp the proof mass motion of an accelerometer while achieving an underdamped resonator. In an example of an in-plane micro-electromechanical systems (MEMS) VBA, the proof mass may contain one or more damping combs that include one or more banks of rotor comb fingers attached to the proof mass. The rotor comb fingers may be interdigitated with stator comb fingers that are attached to fixed geometry. These damping comb fingers may provide air damping for the proof mass when the MEMS die is placed into a package containing a pressure above a vacuum. The geometry of the damping combs with a reduced air gap and large overlap area between the rotor comb fingers and stator comb fingers. The geometry of resonator of the VBA of this disclosure may be configured to avoid air damping.

A system for detecting steps of a user includes processing circuitry and a sensor configured to detect a variation of electrostatic charge of the user during a step of the user and generate a charge-variation signal. An accelerometer is configured to detect an acceleration as a consequence of the step and generate an acceleration signal. The processing circuitry is configured to: acquire the charge-variation signal; acquire the acceleration signal; detect, in the charge-variation signal, a first characteristic identifying the step; detect, in the acceleration signal, a second characteristic identifying the step. If both of the first and second characteristics have been detected, the presence of the step can be validated.

A method may comprise obtaining, during drilling operations within a wellbore, two-dimensional accelerometer data with an accelerometer on a rotating downhole tool, determining a radial offset of the accelerometer based on the two-dimensional accelerometer data, and determining a centripetal acceleration of the accelerometer based on the two-dimensional accelerometer data. A system may comprise one or more x-axis accelerometers disposed on a bottom hole assembly, one or more y-axis accelerometers disposed on the bottom hole assembly, an analog to digital converter, wherein the analog to digital converter converts an analog signal from the one or more x-axis accelerometers and the one or more y-axis accelerometers to a digital signal, and a computing subsystem.

Accelerometers are described herein that have RMS outputs. For instance, an example accelerometer may include a MEMS device and an ASIC. The MEMS device includes a structure having an attribute that changes in response to acceleration of an object. The ASIC determines acceleration of the object based at least in part on changes in the attribute. The ASIC includes analog circuitry, an ADC, and firmware. The analog circuitry measures the changes in the attribute and generates analog signals that represent the changes. The ADC converts the analog signals to digital signals. The firmware includes RMS firmware. The RMS firmware performs an RMS calculation on a representation of the digital signals to provide an RMS value that represents an amount of the acceleration of the object.

Provided is a sensor that is highly accurate while ensuring reduced power consumption. A sensor is an electronic circuit that includes a sensor element, an analog filter, an A/D converter, and first and second electronic circuit. The analog filter filters a waveform that includes a sensor signal from the sensor element and noise based on a servo signal. The A/D converter converts the waveform filtered by the analog filter into a first digital signal. The first electronic circuit includes a digital filter and acquires a second digital signal by performing signal processing including at least a filtering process on the servo signal by using the digital filter. The second electronic circuit acquires a third digital signal by subtracting the second digital signal from the first digital signal. A setting for the signal processing for acquiring the second digital signal is changed on the basis of the third digital signal.

Disclosed is a MEMS device, comprising: a movable electrode plate; a first electrode plate and a first feedback electrode plate located on a first side of the movable electrode plate; a second electrode plate and a second feedback electrode plate located on a second side of the movable electrode plate. The first electrode plate, the first feedback electrode plate, the second electrode plate, the second feedback electrode plate respectively form a first capacitor, a first feedback capacitor, a second capacitor and a second feedback capacitor with the movable electrode plate. The first and the second capacitors are coupled to a detection circuit for performing differential detection on the first and the second capacitors; the first feedback capacitor and the second feedback capacitor are coupled to a feedback circuit for eliminating nonlinear relationship between an output voltage of the detection circuit and a displacement of the movable electrode plate.

In a MEMS electrostatic capacitor type acceleration sensor, the manufacturing costs of MEMS elements are reduced, and at the same time, the variations of the electrical and mechanical characteristics of the MEMS elements are reduced. A detection circuit generates a voltage signal corresponding to the product of a difference between the two capacitance values of a pair of MEMS capacitors and a servo signal. A modulation circuit outputs a signal corresponding to the difference between the capacitance values using the servo signal. The control circuit outputs the servo signal on the basis of a signal corresponding to the difference between the capacitance values.

A method for operating a micromechanical inertial sensor, including: translating an acceleration into a deflection of two detection electrodes that are displaced in opposite directions; ascertaining a difference in the spacing of the two detection electrodes; converting the difference in the spacing into an acceleration value using a scaling factor; and applying a linearization process to the acceleration value.

An aircraft recorder system is provided in which a vibration sensor including at least one of a micro-electromechanical systems (MEMS) microphone and a MEMS accelerometer. The system further includes a cockpit voice recorder (CVR) and an active microphone. The active microphone and the vibration sensor each output signals to a signal processor including a subtractor configured to output, to the CVR, a signal that is a result of a subtraction of the signal from the vibration sensor from the signal from the active microphone.