Patents Assigned to Atlantic Inertial Systems Limited

Patent number: 11041724Abstract: A navigation system comprising: an inertial navigation system arranged to output a first position estimate; a terrain based navigation unit arranged to output a second position estimate; a gravity based navigation unit arranged to output a third position estimate; a stored gravity map arranged to receive a position and to output gravity information for that position; and an iterative algorithm unit arranged to determine an INS error state in each iteration; wherein in each iteration the iterative algorithm unit is arranged to: receive the first position estimate, the second position estimate, and the third position estimate; determine a gravity corrected position estimate based on the first position estimate, the INS error state and the gravity information; and update the INS error state for the next iteration based on the INS error state, the gravity corrected position estimate, the second position estimate and the third position estimate.Type: GrantFiled: October 16, 2017Date of Patent: June 22, 2021Assignee: ATLANTIC INERTIAL SYSTEMS LIMITEDInventors: Alan Malvern, Nicholas R. Wilkinson

Patent number: 11029159Abstract: A terrainbased navigation system include at least three laser range finders, each fixedly mounted to a vehicle body, each pointing in a different direction and arranged such that they can be used to calculate terrain gradient in two dimensions. Existing terrainbased navigation systems for aircraft that use a radar altimeter to determine the distance of the vehicle from the ground make use of the large field of view of the radar altimeter. The first return signal from the radar altimeter may not be from directly below the aircraft, but will be interpreted as being directly below the aircraft, thereby impairing the chances of obtaining a terrain match, or impairing the accuracy of a terrain match. The use of a plurality of laser range finders each fixedly mounted to the vehicle body allows more terrain information to be obtained as the terrain can be detected from the plurality of different directions.Type: GrantFiled: September 9, 2019Date of Patent: June 8, 2021Assignee: ATLANTIC INERTIAL SYSTEMS LIMITEDInventor: Geoffrey Thomas Henderson

Patent number: 11015957Abstract: A navigation system comprising: an inertial navigation system arranged to output a first position estimate; a terrain based navigation unit arranged to output a second position estimate; a stored gravity map arranged to receive a position and to output gravity information for that position; and an iterative algorithm unit arranged to determine an INS error state in each iteration; wherein in each iteration the iterative algorithm unit is arranged to: receive the first position estimate and the second position estimate; determine a gravity corrected position estimate based on the first position estimate, the INS error state and the gravity information; and update the INS error state for the next iteration based on the INS error state, the gravity corrected position estimate and the second position estimate.Type: GrantFiled: October 13, 2017Date of Patent: May 25, 2021Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITEDInventor: Nicholas R. Wilkinson

Patent number: 10928199Abstract: A vibrating structure angular rate sensor is provided which comprises a substrate; a plurality of flexible supporting structures fixed to the substrate; an annular member which is flexibly supported by the plurality of supporting structures to move elastically relative to the substrate; and an electrical drive system configured to drive the annular member to oscillate in a primary mode of oscillation with a resonant frequency f1. The plurality of supporting structures comprises at least one active supporting structure which carries an active electrical connection from the annular member to the drive system; and at least one passive supporting structure which does not carry an active electrical connection from the annular member to the drive system.Type: GrantFiled: January 30, 2019Date of Patent: February 23, 2021Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITEDInventor: Kevin Townsend

Patent number: 10900994Abstract: 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 inphase and antiphase 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 pickoff 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.Type: GrantFiled: October 13, 2017Date of Patent: January 26, 2021Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITEDInventor: Alan Malvern

Patent number: 10884020Abstract: A sensing structure for an accelerometer includes a support and a proof mass mounted thereto by flexible legs. The proof mass has moveable electrode fingers perpendicular to the sensing direction and at least four fixed capacitor electrodes, with fixed capacitor electrode fingers perpendicular to the sensing direction. The fixed capacitor electrode fingers interdigitate with the movable electrode fingers and the proof mass is mounted to the support by an anchor on a centre line of the proof mass. The proof mass has an outer frame surrounding the fixed capacitor electrodes and the flexible legs extend laterally inwardly from the proof mass to the anchor. The fixed capacitor electrodes comprise two inner electrodes, one on each side of the proof mass centre line, and two outer electrodes, one on each side of the proof mass centre line.Type: GrantFiled: August 7, 2018Date of Patent: January 5, 2021Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITEDInventors: Alan Malvern, Louise Snell

Patent number: 10866098Abstract: A vibrating structure angular rate sensor comprises a substrate; a plurality of supporting structures fixed to the substrate; an annular member flexibly supported by the plurality of supporting structures 204; a drive system arranged to apply a periodic driving force such that the annular member 202 oscillates, in use, in a primary mode of vibration at a resonant frequency f1, with an amplitude of motion that generates a restoring force from the plurality of supporting structures 204; and a pickoff system arranged to determine the amplitude of motion of a secondary mode of vibration at a resonant frequency f2, in which oscillation of the annular member 202 is induced by the Coriolis force resulting from an angular rate experienced by the sensor 100. In use, the restoring force has a nonlinear relationship with the amplitude of motion and a number p of supporting structures is selected such that f1=f2.Type: GrantFiled: October 15, 2018Date of Patent: December 15, 2020Assignee: ATLANTIC INERTIAL SYSTEMS LIMITEDInventors: Stewart McWilliam, Atanas Popov

Patent number: 10816339Abstract: An annular resonator for a vibrating structure angular rate sensor comprises a planar annular member that lies in the XY plane and one or more supporting structures arranged to flexibly support the annular member in the XY plane. The one or more supporting structures each comprise a radial portion, extending radially from the annular member and having a first thickness in the XY plane, and a circumferential portion, extending circumferentially from the radial portion and having a second thickness in the XY plane, wherein the first thickness is greater than the second thickness.Type: GrantFiled: July 9, 2018Date of Patent: October 27, 2020Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITEDInventor: Jason Baxter

Patent number: 10782147Abstract: A method for determining an operational characteristic of a vibrating structure gyroscope having a movable mass includes: driving the mass to oscillate along a first, predefined path; rotating the vibrating structure gyroscope so as to oscillate the mass along a second path, wherein the second path is different to the first, predefined path; sensing the oscillation of the mass along the second path so as to generate a sensing signal; converting the sensing signal into an inphase signal and an outofphase signal using a demodulator, wherein the inphase signal is in phase with the oscillation of the mass along the first path, and the outofphase signal is out of phase with the inphase signal.Type: GrantFiled: February 26, 2018Date of Patent: September 22, 2020Assignee: ATLANTIC INERTIAL SYSTEMS LIMITEDInventors: Thomas Mansfield, Matthew Williamson

Patent number: 10775404Abstract: A method for closed loop operation of a capacitive accelerometer uses a single current source (62) and a single current sink (64) to apply an inphase drive signal V1? to a first set of fixed capacitive electrode fingers and a corresponding antiphase drive signal V2? to a second set of fixed capacitive electrode fingers. This provides a net electrostatic restoring force on the proof mass for balancing the inertial force of the applied acceleration and maintains the proof mass at a null position.Type: GrantFiled: June 26, 2015Date of Patent: September 15, 2020Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITEDInventors: Kevin Townsend, Michael Durston, Douglas Sitch

Patent number: 10753745Abstract: There is provided a method of sensing a rotation rate using a vibrating structure gyroscope, said gyroscope comprising an electronic control system comprising one or more control loops, wherein at least one of said control loops comprises a filter having a variable time constant, said method comprising the steps of: determining or estimating a characteristic of the vibrating structure of said gyroscope; and adapting or varying said time constant of said filter with the determined or estimated characteristic of said vibrating structure.Type: GrantFiled: January 26, 2016Date of Patent: August 25, 2020Assignee: ATLANTIC INERTIAL SYSTEMS LIMITEDInventors: Kevin Townsend, Andrew Clifford, Nicholas Wilkinson

Patent number: 10746564Abstract: A method of determining whether parametric performance of an inertial sensor has been degraded comprises: recording first data output from an inertial sensor; then recording second data output from the inertial sensor; comparing the first data output with the second data output; and determining whether the parametric performance of the inertial sensor has been degraded based on the comparison between the first and second data output.Type: GrantFiled: August 5, 2016Date of Patent: August 18, 2020Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITEDInventor: Christopher Gregory

Patent number: 10731986Abstract: A digitally controlled voltage controlled oscillator comprising an Nbit digital to analogue convertor arranged to receive a frequency change demand signal as a digital Nbit word, and having an output provided via an integrator to a voltage controlled oscillator configured to provide a frequency output.Type: GrantFiled: October 27, 2015Date of Patent: August 4, 2020Assignee: ATLANTIC INERTIAL SYSTEMS LIMITEDInventors: Kevin Townsend, Michael Durston

Patent number: 10670623Abstract: A capacitive accelerometer comprises: a substantially planar proof mass mounted to a fixed substrate by flexible support legs so as to be linearly moveable in an inplane sensing direction. The proof mass comprises first and second sets of moveable capacitive electrode fingers. First and second sets of fixed capacitive electrode fingers interdigitates with the first and second sets of moveable electrode fingers respectively. A set of moveable damping fingers extend from the proof mass substantially perpendicular to the sensing direction, laterally spaced in the sensing direction. A set of fixed damping fingers mounted to the fixed substrate interdigitates with the set of moveable damping fingers and comprises an electrical connection to the proof mass so that the interdigitated damping fingers are electrically common. The damping fingers are mounted in a gaseous medium that provides a damping effect.Type: GrantFiled: August 11, 2016Date of Patent: June 2, 2020Assignee: Atlantic Inertial Systems LimitedInventors: Kiran Mysore Harish, Alan Malvern

Patent number: 10670400Abstract: A vibrating structure gyroscope includes an annular resonator arranged to vibrate in a plane in response to electrostatic driving forces and a set of capacitive drive electrodes arranged to apply a voltage creating an electrostatic driving force to excite a primary cos n? resonance along a primary axis at a primary frequency fP, such that Coriolis forces, resulting from an angular rate applied about an outofplane axis, induce a secondary cos n? resonance along a secondary axis at a secondary frequency fS. The gyroscope also includes digitallycontrolled first and second sets to creating a static electrostatic balancing.Type: GrantFiled: September 27, 2018Date of Patent: June 2, 2020Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITEDInventors: Kevin Townsend, Andrew Kazer

Patent number: 10571485Abstract: In a method for open loop operation of a capacitive accelerometer, a first mode of operation comprises electrically measuring a deflection of a proof mass (204) from the null position under an applied acceleration using a pickoff amplifier (206) set to a reference voltage Vcm. A second mode of operation comprises applying electrostatic forces in order to cause the proof mass (204) to deflect from the null position, and electrically measuring the forced deflection so caused. In the second mode of operation the pickoff amplifier (206) has its input (211) switched from Vcm to Vss, using a reference control circuit (209), so that drive amplifiers (210) can apply different voltages Vdd to the proof mass (204) and associated fixed electrodes (202).Type: GrantFiled: June 5, 2015Date of Patent: February 25, 2020Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITEDInventors: Michael Durston, Kevin Townsend

Patent number: 10571271Abstract: An inertial measurement system comprising: a first, roll gyro with an axis oriented substantially parallel to the spin axis of the projectile; a second gyro and a third gyro with axes arranged with respect to the roll gyro; a controller, arranged to: compute a current projectile attitude from the outputs of the first, second and third gyros; operate a Kalman filter that receives a plurality of measurement inputs including at least roll angle, pitch angle and yaw angle and that outputs at least a roll angle error; initialise the Kalman filter with a roll angle error uncertainty representative of a substantially unknown roll angle; generate at least one pseudomeasurement from stored expected flight data; provide said pseudomeasurement(s) to the corresponding measurement input of the Kalman filter; and apply the roll angle error from the Kalman filter as a correction to the roll angle.Type: GrantFiled: April 27, 2018Date of Patent: February 25, 2020Assignee: ATLANTIC INERTIAL SYSTEMS LIMITEDInventors: Nicholas Mark Faulkner, John Keith Sheard

Patent number: 10563987Abstract: An inertial measurement system for a spinning projectile comprising: first (roll), second and third gyros with axes arranged such that they define a three dimensional coordinate system; at least a first linear accelerometer; a controller, arranged to: compute a current projectile attitude comprising a roll angle, a pitch angle and a yaw angle; compute a current velocity vector from the accelerometer; combine a magnitude of said velocity vector with an expected direction for said vector to form a pseudovelocity vector; provide the velocity vector and the pseudovelocity vector to a Kalman filter that outputs a roll gyro scale factor error calculated as a function of the difference between the velocity vector and the pseudovelocity vector; and apply the roll gyro scale factor error from the Kalman filter as a correction to the output of the roll gyro.Type: GrantFiled: May 25, 2017Date of Patent: February 18, 2020Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITEDInventors: Nicholas M. Faulkner, John Keith Sheard

Patent number: 10539421Abstract: An inertial measurement system (200) for a longitudinal projectile, comprising a first, roll gyro to be oriented substantially parallel to the longitudinal axis of the projectile; a second gyro and a third gyro with axes arranged with respect to the roll gyro such that they define a three dimensional coordinate system.Type: GrantFiled: October 27, 2015Date of Patent: January 21, 2020Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITEDInventors: John Keith Sheard, Nicholas Mark Faulkner

Patent number: 10422811Abstract: A sensing structure for an accelerometer includes a support and a proof mass mounted to the support by flexible legs for inplane movement in response to an applied acceleration along a sensing direction. The proof mass includes a plurality of moveable electrode fingers extending substantially perpendicular to the sensing direction and spaced apart in the sensing direction. The structure also includes at least one pair of fixed capacitor electrodes comprising first and second sets of fixed electrode fingers extending substantially perpendicular to the sensing direction and spaced apart in the sensing direction; the first set of fixed electrode fingers arranged to interdigitate with the moveable electrode fingers with a first offset in one direction from a median line therebetween, and the second set of fixed electrode fingers arranged to interdigitate with the moveable electrode fingers with a second offset in the opposite direction from a median line therebetween.Type: GrantFiled: February 16, 2015Date of Patent: September 24, 2019Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITEDInventors: Alan Richard Malvern, Kiran Harish