A movable member coupled to a displacement detector via a void is disposed with respect to a fixed member to which a coil is fixed. By disposing the coil in a closed loop magnetic circuit including a permanent magnet, the movable-side member, and the fixed member, a Lorentz force for moving the movable-side member in the axial direction is generated.

The disclosure describes a magnetic circuit assembly that includes a magnet assembly and an excitation ring. The magnet assembly defines an input axis and includes a pole piece and a magnet underlying the pole piece. The excitation ring includes a base and an outer ring positioned around the magnet assembly. The base includes a platform layer underlying the magnet and a base layer underlying the platform layer. The outer ring overlies the base layer. An inner portion of the outer ring faces the magnet assembly and an outer portion of the outer ring is configured to couple to an outer radial portion of a proof mass assembly. The pole piece and the platform layer include a high magnetic permeability material.

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.

An accelerometer includes a first stator, a second stator, a proof mass assembly disposed between the first stator and second stator, and a controller. The first stator includes a first magnet and the second stator includes a second magnet. The proof mass assembly includes a first coil configured to receive a first amount of current and a second coil configured to receive a second amount of current. The controller is configured to distribute the first amount of current to the first coil and the second amount of current to the second coil. The first amount of current is different than the second amount of current.

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.

An accelerometer includes an upper stator, a lower stator, and a proof mass assembly disposed between the upper and the lower stator. At least one of the upper stator or the lower stator includes an excitation ring, a magnet coupled to the excitation ring, and an asymmetric pole piece coupled to a top surface of the magnet. The asymmetric pole piece covers at least a portion of the top surface of the magnet such that a center of magnetic flux associated with the at least one of the upper stator or the lower stator is aligned with a center of mass of the proof mass assembly.

A method for rebalancing a group of accelerometers in a gravity gradiometer instrument (GGI) includes the steps of defining and implementing a number of groupwise actuation constrainment modes based on a design of the gravity gradiometer instrument and its accelerometers. Implementing one constrainment mode comprises differentially scaling and distributing a single electrical current to multiple accelerometers' rebalance circuitry to cancel a specific acceleration effect experienced by the group of accelerometers or gradiometer as a whole. Superposition of a number of such modes enables rebalancing the full acceleration environment experienced by the group of accelerometers, given negligible local differential acceleration effects specific to, say, an individual accelerometer of the assembly. Mathematically, the multiple of constrainment modes are encapsulated by an actuation or constrainment modal influence matrix, arranged one mode per column of the matrix, and the electrical currents of respective modes are encapsulated in a vector listing of currents.

A high-precision magnetic suspension accelerometer for measuring the linear acceleration of a spacecraft is provided, comprising a magnetically shielded vacuum chamber system, a magnetic displacement sensing system, a magnetic suspension control system and a small magnetic proof mass. A optical coherence displacement detection technique is utilized for precisely measuring the position and the posture of the small magnetic proof mass in real time, and a magnetic suspension control technique is utilized for precisely controlling the position and the posture of the small magnetic proof mass to be brought back to the origin, so as to keep the small magnetic proof mass in the center of the systemic inner chamber. When the spacecraft is subject to a non-conservative force, the magnitude and direction of the acceleration can be precisely measured via the measurement of currents in the position control coils due to the acceleration of the spacecraft proportional to the currents of the position control coils. The accelerometer of the invention can avoid the technical bottleneck of high-precision machining, is easy to be produced and can achieve more high-precision measurement of the acceleration vector.

The present disclosure discloses a vertical superconducting magnetic mass-spring oscillator with an adjustable natural frequency, comprising: a proof mass, a negative-stiffness superconducting coil and a positive-stiffness superconducting coil; the negative-stiffness superconducting coil is mounted at an opening of a semi-closed space of the proof mass, so that a part of magnetic lines of the negative-stiffness superconducting coil are in a compressed state in a closed space of the proof mass, and the other part of the magnetic lines of the negative-stiffness superconducting coil are in an expanded state outside the closed space of the proof mass; a vertical magnetic repulsive force applied to the proof mass by the negative-stiffness superconducting coil varies with a displacement of the proof mass from an equilibrium position, with the variation magnitude proportional to the displacement and the variation direction the same as the displacement direction; and the positive-stiffness superconducting coil is mounted in the semi-closed space of the proof mass, and a vertical magnetic repulsive force applied to the proof mass by the positive-stiffness superconducting coil varies proportionally to the displacement of the proof mass from the equilibrium position, with the variation direction opposite to the displacement direction. The present disclosure realizes that the natural frequency of the superconducting mass-spring oscillator is adjustable, and meanwhile, the cross-coupling effect of horizontal and vertical degrees of freedom of the proof mass can be reduced.

This disclosure is related to devices, systems, and techniques for determining an acceleration. For example, an accelerometer system includes a proof mass, a pole piece connected to the proof mass, and a coil disposed around the pole piece and connected to the proof mass, where the coil is rectangular in shape. Additionally, the accelerometer system includes circuitry configured to deliver an electrical signal to the coil in order to maintain the proof mass at a null position and determine an electrical current value corresponding to the electrical signal. Additionally, the circuit is configured to identify, based on the electrical current value, an acceleration of the accelerometer system.