Abstract: It is an object of the present invention to reduce noise in a detection circuit for use in a sensor system. According to an aspect of the present invention, provided is a high-sensitivity sensor system which includes an acceleration sensor, a detection circuit system that detects an output of the acceleration sensor, a feedback circuit system including a reference voltage power source that generates a feedback signal to be fed back to the acceleration sensor based on an output of the detection circuit system, and a correction circuit system.

Abstract: Inclinometers with a parallel dipole line (PDL) trap system are provided. In one aspect, an inclinometer includes: a PDL trap having a pair of dipole line magnets, a transparent tube in between the dipole line magnets, and a diamagnetic object within the transparent tube, wherein the diamagnetic object is levitating in between the dipole line magnets; and a sensing system for determining a position z of the diamagnetic object in the PDL trap and for determining an inclination angle ? using the position z of the diamagnetic object in the PDL trap. Techniques to detect the diamagnetic object position using optical, capacitive and manual methods are described. A method for determining an inclination angle ? using the present inclinometers is also provided.

Abstract: A long-period vibration sensor includes an overdamped accelerometer including a magnet fixed to the inside of a casing, a detection coil disposed between magnetic poles formed due to the magnet, a bobbin configured to hold the detection coil, and a support spring configured to support the bobbin in the casing so that the bobbin can vibrate in a predetermined direction, a voltage being outputted from the detection coil when the bobbin is damped, a plurality of digital filters having different frequency characteristics from one another, a selection module configured to select one digital filter from the plurality of digital filters based on an output value of the voltage outputted from the overdamped accelerometer, and a correction module configured to correct the output value of the voltage outputted from the overdamped accelerometer using the digital filter selected by the selection module.

Abstract: A gravity gradiometer having at least three differential accelerometers with a low response to linear accelerations and at least six angular accelerometers that give it the capability of measuring angular rates by integrating the angular accelerations. Both types of accelerometers are based on a compliant mechanism with very low and adjustable stiffness that is achieved by using flexures under compressive load that contribute a negative stiffness to the total elastic response of the mechanism. Both types of accelerometers are operated in a servo-compensation feedback mode so that at no time is the mechanism far from its equilibrium position.

Abstract: A MEMS device has a movable beam, a differential capacitor with a movable electrode that moves in response to the displacement of the movable beam and that is disposed between two stationary electrodes, and a voltage circuit for applying a first voltage to the first stationary electrode, second voltage to the second stationary electrode, and a third voltage to the moveable electrode. The MEMS device also has a monitor operably coupled with the movable beam to monitor the displacement of the movable beam. In some embodiments, the monitor may monitor the distance between the movable electrode and at least one of the stationary electrodes. The MEMS device further has a voltage reducing circuit operatively coupled with the monitor, the movable electrode, and the stationary electrodes.

Abstract: Detecting and/or mitigating the presence of particle contaminants in a MEMS device involves converting benign areas in which particles might become trapped undetectably by electric fields during test to field-free regions by extending otherwise non-functional conductive shield and gate layers and placing the same electrical potential on the conductive shield and gate layers. Particle contaminants can then be moved into detection locations remote from the potential trap areas and having particle detection structures by providing some mechanical disturbance.

Abstract: Detecting and/or mitigating the presence of particle contaminants in a MEMS device involves including MEMS structures that in normal operation are robust against the presence of particles but which can be made sensitive to that presence during a test mode prior to use, e.g.

Abstract: An in-plane, closed-loop Micro Electro-Mechanical Systems (MEMS) accelerometer device with improved performance. An example MEMS device includes one or more components for generating a magnetic flux field perpendicular to a major plane of the device. The device includes substrates, a proof mass, spring elements that flexibly connect the proof mass to the substrate and constrain the proof mass to translate within the major plane of the device which corresponds to a major surface of the proof mass, a plurality of conductive traces located at a position on the proof mass proximate the magnetic flux field, a plurality of conductive springs, each of the springs are electrically connected to a corresponding one of the conductive traces, and a plurality of anchor pads connected to the substrate and one of the conductive springs.

Abstract: Systems and methods for controlling a closed-loop accelerometer system. A system includes an accelerometer with a driver that responds in a nonlinear manner and a rebalancing controller in signal communication with the driver. The rebalancing controller includes a proportional-integral-derivative (PID) control portion having at least one variable gain component. A method includes sensing a movement of a proof mass, determining a static g field based on the sensed movement, setting at least one variable gain component of a PID controller based on the determined static g field, and rebalancing the proof mass using the PID controller.

Abstract: An accelerometer or a seismometer using an in-plane suspension geometry having a suspension plate and at least one fixed capacitive plate. The suspension plate is formed from a single piece and includes an external frame, a pair of flexural elements, and an integrated proof mass between the flexures. The flexural elements allow the proof mass to move in the sensitive direction in the plane of suspension while restricting movement in all off-axis directions. Off-axis motion of the proof mass is minimized by the use of intermediate frames disbursed within and between the flexural elements. Intermediate frames can include motion stops to prevent further relative motion during overload conditions. The device can also include a dampening structure, such as a spring or gas structure that includes a trapezoidal piston and corresponding cylinder, to provide damping during non-powered states. The capacitive plate is made of insulating material.

Abstract: An increased flux density D'Arsonval Micro-Electro-Mechanical Systems (MEMS) device increases flux density. The increased flux density D'Arsonval Micro-Electro-Mechanical Systems (MEMS) device includes a housing, a proof mass suspended within the housing by at least one torsional flexure, a second torsional rebalancing magnet, and a current coil disposed on the proof mass. A portion of the current coil is disposed between the first torsional rebalancing magnet and the second torsional rebalancing magnet. A field generated in response to a current in the current coil interacts with a magnetic field generated by the first torsional rebalancing magnet and the second torsional rebalancing magnet. The magnetic field generates a rebalancing force that stabilizes a position of the proof mass.

Abstract: A closed loop scale factor estimator of an apparatus in one example is configured to compare a measured flex angle of a hemispherical resonator gyroscope (HRG) with a demodulation angle signal to estimate a force-to-rebalance (FTR) scale factor for the HRG, wherein the demodulation angle signal corresponds to an integral of a non-uniform rate signal applied to the HRG.

Abstract: An oversampling electromechanical modulator, including a micro-electromechanical sensor which has a first sensing capacitance and a second sensing capacitance and supplies an analog quantity correlated to the first sensing capacitance and to the second sensing capacitance; a converter stage, which supplies a first numeric signal and a second numeric signal that are correlated to the analog quantity; and a first feedback control circuit for controlling the micro-electromechanical sensor, which supplies an electrical actuation quantity correlated to the second numeric signal.

Abstract: A force-balance accelerometer having a pick-off coil responsive to displacement of a seismic mass from a balance position for providing an output corresponding to the displacement, includes a digital signal processor including tow pulse width modulation generators for converting the output of the pick-up coil to a digital signal, and a torque coil responsive to the digital signal for rebalancing the seismic mass by restoring the mass to the balance position. The processor outputs the digital signal as first and second PWM signals, which control the digital signal.

Abstract: A servo compensating accelerometer includes a top housing half and a bottom housing half rigidly connected together, and each having coaxial threaded openings. A sensing element is positioned between the top and bottom halves and affixed to the bottom half. Top and bottom magnetic systems, each of which has a magnetic conductor, a permanent magnet and a field concentrator, the magnetic systems being mounted within the respective top and bottom halves of the housing using the threaded openings. A momentum sensor includes the top and bottom magnetic systems, and also includes two movable coils mounted on a plate and positioned within the magnetic systems. A differential angle sensor includes toroidal excitation coils located on the permanent magnets, the magnetic systems and the coils of the momentum sensor. Zero bias of the accelerometer's angular displacement sensor is tuned by adjusting the position of the magnetic systems by moving them in the threaded openings.

Abstract: An accelerometer system includes a capacitor plate fixed within a housing and a flexure plate positioned substantially parallel to the capacitor plate a distance therefrom. The distance varies in response to acceleration forces acting upon the flexure plate such that the flexure plate and the capacitor plate generate a capacitance signal. A magnet is coupled to the flexure plate and generates a magnetic field, which moves as the flexure plate flexes. A coil winding around the flexure plate generates a second magnetic field as a function of capacitance signal, thus opposing the flexure plate magnetic field, and thereby returning the flexure plate to a null position.

Abstract: An accelerometer system includes a capacitor plate fixed within a housing and a flexure plate positioned substantially parallel to the capacitor plate a distance therefrom. The distance varies in response to acceleration forces acting upon the flexure plate such that the flexure plate and the capacitor plate generate a capacitance signal. A magnet is coupled to the flexure plate and generates a magnetic field, which moves as the flexure plate flexes. A coil winding around the flexure plate generates a second magnetic field as a function of capacitance signal, thus opposing the flexure plate magnetic field, and thereby returning the flexure plate to a null position.

Abstract: A method of measuring acceleration includes suspending an inertial body using a magnetic fluid; generating a magnetic field within the magnetic fluid; modulating the magnetic field to counteract a change in position of the inertial body relative to sources of the magnetic field due to acceleration; and calculating the acceleration based on the modulation. The calculating step derives the acceleration based on an amount of current through drive coils required for the modulation. The acceleration includes linear acceleration and/or angular acceleration. The drive coils include permanent magnets, electromagnets, or a combination of a permanent magnet and an electromagnet. Sensing coils can be used for detecting the displacement of the inertial body. Each sensing coil can be positioned substantially within a corresponding drive coil. The inertial body can be non-magnetic, weakly magnetic, or have a ferromagnetic coating.

Abstract: The invention relates to an inertial sensor based on the magnetic levitation of an inertial mass comprising an active magnetic bearing unit arranged in such a way as to levitate the inertial mass and characterized by the fact that it furthermore comprises additional active magnetic bearings units arranged in such a way as to control the position of said inertial mass along three independent axis and to create, for any of said independent axis, restoring forces that can be oriented in any of the two directions of these independent axis.

Abstract: A housing for a magnetofluidic sensor where the sensor has a plurality of drive magnet assemblies, magnetic fluid and an inertial body. The housing has a plurality of ports for securing respective drive magnet assemblies, such that a portion of each drive magnet assembly is positioned within the housing proximate the magnetic fluid. Each drive magnet assembly includes a magnetic field source for creating a magnetic field within the magnetic fluid for acting upon the inertial body. Each drive magnet assembly also includes a sensing element for sensing movement of the inertial body within the magnetic fluid.

Abstract: An oversampling electromechanical modulator, including a micro-electromechanical sensor which has a first sensing capacitance and a second sensing capacitance and supplies an analog quantity correlated to the first sensing capacitance and to the second sensing capacitance; a converter stage, which supplies a first numeric signal and a second numeric signal that are correlated to the analog quantity; and a first feedback control circuit for controlling the micro-electromechanical sensor, which supplies an electrical actuation quantity correlated to the second numeric signal.

Abstract: An accelerometer or a seismometer using an in-plane suspension geometry having a suspension plate and at least one fixed capacitive plate. The suspension plate is formed from a single piece and includes an external frame, a pair of flexural elements, and an integrated proof mass between the flexures. The flexural elements allow the proof mass to move in the sensitive direction in the plane of suspension while restricting movement in all off-axis directions. Off-axis motion of the proof mass is minimized by the use of intermediate frames disbursed within and between the flexural elements. Intermediate frames can include motion stops to prevent further relative motion during overload conditions. The device can also include a dampening structure, such as a spring or gas structure that includes a trapezoidal piston and corresponding cylinder, to provide damping during non-powered states.

Abstract: The invention concerns methods and apparatus for improving the performance of a force-balance accelerometer based upon a conventional, single-coil, velocity geophone. Specifically, the operating temperature range is increased through the use of both a temperature-compensating reference impedance, and a new electronic circuit architecture. Two specific types of temperature-compensating reference impedances are disclosed. One is a pure DC-resistance, with the temperature coefficient of the DC resistance matching that of a single coil of a conventional geophone. A second reference impedance adds a series reactance which closely matches the ratio of total impedance to DC-resistance, and the temperature coefficient of this ratio, with that of the geophone coil. A method is also described which provides for decreased magnitude of a reference impedance required in an accelerometer. This allows for a significant reduction in the physical size of the reference impedance.

Abstract: An extremely sensitive accelerometer suitable for use in extreme temperatures such as those encountered during space travel is formed by levitating a magnet in a box or sphere composed of diamagnetic material such as pyrolytic carbon, and a means for measuring the position of the magnet within the enclosure is provided so that over time, the position of the magnet can be monitored. Knowing the mass of the suspended magnet, the displacement over time of the magnetic can be used to calculate acceleration, which can then be used to determine position of a space vehicle.

Abstract: A mass is levitated with respect to a base, at least one of which is comprised of a diamagnetic material, with the levitated mass also having a permanent magnetic property. A second permanent magnet is optionally configured such that it attracts the levitation mass away from the base to overcome gravitational force on the mass, thereby suspending the mass over the surface of the base. The mass is contained in a nonmagnetic, non-shielding and optionally optically-transparent housing so as to limit its excursion within a range of levitation positions. A position measurement means such as a laser interferometer, capacitance detector, or pickup coil is configured to measure positional deviations of the mass in response to incident pressure wave, the output of which being an electronic signal representing the pressure wave.

Abstract: A mass is levitated with respect to a base at least one of which is comprised of a diamagnetic material, and the levitation mass also having a permanent magnetic property. A second permanent magnet is configured such that it attracts the levitation mass away from said base surface with sufficient magnetic force to overcome gravitational force on the mass, thereby suspending the mass over the surface of the base. The mass is levitated at room temperature, eliminating need for cryogenic mechanisms and materials, and is contained in a nonmagnetic, non-shielding optically-transparent housing so as to limit its excursion within a range of levitation positions. A non-intrusive position or distance measurement means may be optionally configured with the system, such as a laser interferometer, thereby allowing the levitated mass to act as a gravimetric device.

Abstract: An arcuate reed for use with a capacitance type accelerometer proof mass. The reed includes grooves for improved gas damping and reduced latch-up without a reduction in damping effects.

Abstract: A quasi-optical system is provided. More specifically, a quasi-optical system is provided comprising various embodiments of quasi-optical grids (such as arrays or layers and the like) with reconfigurable quasi-optical unit cells. The quasi-optical system, grids and unit cells are configured to control an incident beam in a variety of ways.

Abstract: A high sensitivity, Z-axis, capacitive microaccelerometer having stiff sense/feedback electrodes and a method of its manufacture on a single-side of a semiconductor wafer are provided. The microaccelerometer is manufactured out of a single silicon wafer and has a silicon-wafer-thick proof mass, small and controllable damping, large capacitance variation and can be operated in a force-rebalanced control loop. One of the electrodes moves with the proof mass relative to the other electrode which is fixed. The multiple, stiffened electrodes have embedded therein damping holes to facilitate force-rebalanced operation of the device and to control the damping factor. Using the whole silicon wafer to form the thick large proof mass and using thin sacrificial layers to form narrow uniform capacitor air gaps over large areas provide large-capacitance sensitivity. The manufacturing process is simple and thus results in low cost and high yield manufacturing.

Abstract: A method of mapping diagonal rows and columns of two-dimensional grid elements to rectangular rows and columns of two-dimensional grid elements. The method is of particular use with a spatial light modulator in optical equalization application.

Abstract: An accelerometer had a movable electrode between two fixed electrodes to form a differential capacitor. Drivers provide AC drive signals to the fixed electrodes. The movable electrode is coupled through reading circuitry to an output terminal. In response to a sensed acceleration, feedback is provided from the output terminal to one or both drivers to null any AC signal on the movable electrode and to keep the electrostatic forces between the movable electrode and each of the fixed electrodes equal.

Abstract: The invention concerns methods and apparatus for improving the performance of a force-balance accelerometer based upon a conventional, single-coil, velocity geophone. Specifically, the operating temperature range is increased through the use of both a temperature-compensating reference impedance, and a new electronic circuit architecture. Two specific types of temperature-compensating reference impedances are disclosed. One is a pure DC-resistance, with the temperature coefficient of the DC resistance matching that of a single coil of a conventional geophone. A second reference impedance adds a series reactance which closely matches the ratio of total impedance to DC-resistance, and the temperature coefficient of this ratio, with that of the geophone coil.

Abstract: There is provided a displacement sensor including a moving member composed of a magnetic body; a pair of stators each composed of a magnetic body and arranged opposed to each other with respect to the moving member, the stators including driving coils and position detectors corresponding to the driving coils, respectively; and a control unit for driving, based on a detection output coming from the position detectors, the driving coils with an electric power corresponding to intervals between the moving member and the stators so that the moving member is balanced at an intermediate position between the stators and for computing a force or acceleration applied to the moving member with a driving electric power of the driving coils. A mobile data collecting apparatus utilizing the displacement sensor is also disclosed.

Abstract: An improved microsystems testing and characterization system which allows the system user to identify specific structures, and thereby to initiate an automated testing sequence to be applied to that structure or a series of structures. The integrated control system that governs the present invention automates the power supply to the device, the precision motion control of all components, the sensor operation, data processing and data presentation. Therefore operation is autonomous once the microstructure is in place and the testing sequence is specified. The integrated testing system can be used to perform tests on an entire wafer or on a single die.

Abstract: Rotational motion about at least two different axes may be resolved to measure the direction, magnitude and pivot point of the rotational displacements In some embodiments, these measurements may be made by a device which may be integrated into a silicon substrate using conventional silicon processing techniques. For example, a pair of accelerometers may be formed by a pair of cantilevered beam arrays. Rotational displacement of a camera imaging sensor, for example, may use such accelerometers integrated into the same silicon substrate forming the imaging sensor.