An example transducer includes an upper magnetic circuit assembly including an upper excitation ring, a lower magnetic circuit assembly including a lower excitation ring, and a proof mass assembly positioned between the upper and lower magnetic circuit assemblies. A coefficient of thermal expansion (CTE) of the proof mass assembly is lower than a CTE of each of the upper and lower excitation rings. The transduces also includes an outer support structure coupled to an outer surface of each of the upper and lower excitation rings, and the outer support structure includes at least one cutout configured to reduce a circumferential stiffness of the outer support structure.

An accelerometer closed loop control system comprising: a capacitive accelerometer comprising a proof mass moveable relative to first and second fixed capacitor electrodes; a PWM generator to generate in-phase and anti-phase PWM drive signals with an adjustable mark/space ratio, wherein said drive signals are applied to the first and second electrodes such that they are charged alternately; an output signal detector to detect a pick-off signal from the accelerometer representing a displacement of the proof mass from a null position to provide an error signal, wherein the null position is the position of the proof mass relative to the fixed electrodes when no acceleration is applied; a PWM servo operating in closed loop to vary the mark/space ratio of said PWM drive signals in response to the error signal so that mechanical inertial forces are balanced by electrostatic forces.

An example accelerometer includes a first excitation ring comprising a first material having a first coefficient of thermal expansion (CTE), a second excitation ring comprising the first material having the first CTE; and a proof mass assembly disposed between and in contact with the first excitation ring and the second excitation ring. The proof mass assembly comprises a second material having a second CTE, wherein a difference between the first CTE and the second CTE is equal to or less than 0.5 parts per million per degree Celsius (ppm/ C.).

The method and system for determining position with improved calibration allows a device to initiate activity at the proper location, such as navigating a drill bit through a rock formation. A pair of position sensors in opposite orientations generates position data signals. A temperature sensor detects temperature and duration of the temperature. An adjusted plastic bias value is determined by a processor module based on the temperature data signal, the duration of the temperature, and the position data signals so as to account for bias and hysteresis errors and error correction based on the opposing orientations of the pair of position sensors. A position value is set according to the adjusted plastic bias value so that the position value is more accurate. The activity of the terminal device is initiated or maintained according to the position value calibrated by the adjusted plastic bias value.

Systems and methods are disclosed for generating temperature compensated acceleration data in both analog and digital format from a torque balance accelerometer (TBA). During manufacture of the TBA, a calibration process is used consisting of cooling and heating the TBA to discrete temperatures within a range and at each discrete temperature measuring the TBA scale factor and offset. After collecting scale and offset data, said data is loaded into the memory of the TBA.

During field operation, sensing a current temperature, retrieving the closest scale and offset correction factors from memory of the TBA, and performing linear interpolation to generate a temperature-compensated output for the TBA.

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. A new method of soldering the capacitive plate to the suspension plate is also disclosed.

An example Micro Electro-Mechanical Systems (MEMS) accelerometer device includes a proof mass comprising at least one of one or more isolated conductive coil traces or one or more pick-off combs within the proof mass, the one or more pick-off combs comprising a plurality of pick-off comb tines; a pole-piece layer coupled to the proof mass; and a return-path layer coupled to the proof mass, wherein the at least one of the one or more isolated conductive coil traces or the one or more pick-off combs are formed by selective laser etching.

An example proof mass includes a substrate; one or more etched apertures in the substrate; and one or more integrated coils, wherein the one or more etched apertures are formed by selective laser etching, wherein the one or more integrated coils are formed by laser ablation.

An accelerometer includes an enclosure coupled to one or more mechanical interposers. The interposers are configured to couple the enclosure to a magnetic assembly and the magnetic assembly is configured to couple to a proof mass. The accelerometer may include electrical circuitry having a torquer coil coupled to the proof mass, where the electrical circuitry may be configured to generate an electrical signal based on an acceleration of the accelerometer. Orienting the coupling of the of the enclosure to the magnetic assembly, temperature strain on the accelerometer may be relieved.

A remote sensor based on speckle tracking which uses an inertial-optical accelerometer is provided. The remote sensor makes it possible to correct the speckle pattern correlation centroid value in the presence of displacements due to vibrational noise. The inertial-optical accelerometer instantaneously highlights displacements of the sensor relative to an inertial reference, that is of a mass immovable with respect to the fixed stars, installed in the optical axis of the remote sensor.