Patents Assigned to Atlantic Inertial Systems Limited
  • Patent number: 11041724
    Abstract: 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: Grant
    Filed: October 16, 2017
    Date of Patent: June 22, 2021
    Assignee: ATLANTIC INERTIAL SYSTEMS LIMITED
    Inventors: Alan Malvern, Nicholas R. Wilkinson
  • Patent number: 11029159
    Abstract: A terrain-based 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 terrain-based 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: Grant
    Filed: September 9, 2019
    Date of Patent: June 8, 2021
    Assignee: ATLANTIC INERTIAL SYSTEMS LIMITED
    Inventor: Geoffrey Thomas Henderson
  • Patent number: 11015957
    Abstract: 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: Grant
    Filed: October 13, 2017
    Date of Patent: May 25, 2021
    Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITED
    Inventor: Nicholas R. Wilkinson
  • Patent number: 10928199
    Abstract: 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: Grant
    Filed: January 30, 2019
    Date of Patent: February 23, 2021
    Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITED
    Inventor: Kevin Townsend
  • Patent number: 10900994
    Abstract: 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.
    Type: Grant
    Filed: October 13, 2017
    Date of Patent: January 26, 2021
    Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITED
    Inventor: Alan Malvern
  • Patent number: 10884020
    Abstract: 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: Grant
    Filed: August 7, 2018
    Date of Patent: January 5, 2021
    Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITED
    Inventors: Alan Malvern, Louise Snell
  • Patent number: 10866098
    Abstract: 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 pick-off 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 non-linear relationship with the amplitude of motion and a number p of supporting structures is selected such that f1=f2.
    Type: Grant
    Filed: October 15, 2018
    Date of Patent: December 15, 2020
    Assignee: ATLANTIC INERTIAL SYSTEMS LIMITED
    Inventors: Stewart McWilliam, Atanas Popov
  • Patent number: 10816339
    Abstract: An annular resonator for a vibrating structure angular rate sensor comprises a planar annular member that lies in the X-Y plane and one or more supporting structures arranged to flexibly support the annular member in the X-Y 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 X-Y plane, and a circumferential portion, extending circumferentially from the radial portion and having a second thickness in the X-Y plane, wherein the first thickness is greater than the second thickness.
    Type: Grant
    Filed: July 9, 2018
    Date of Patent: October 27, 2020
    Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITED
    Inventor: Jason Baxter
  • Patent number: 10782147
    Abstract: 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 in-phase signal and an out-of-phase signal using a demodulator, wherein the in-phase signal is in phase with the oscillation of the mass along the first path, and the out-of-phase signal is out of phase with the in-phase signal.
    Type: Grant
    Filed: February 26, 2018
    Date of Patent: September 22, 2020
    Assignee: ATLANTIC INERTIAL SYSTEMS LIMITED
    Inventors: Thomas Mansfield, Matthew Williamson
  • Patent number: 10775404
    Abstract: 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 in-phase drive signal V1? to a first set of fixed capacitive electrode fingers and a corresponding anti-phase 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: Grant
    Filed: June 26, 2015
    Date of Patent: September 15, 2020
    Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITED
    Inventors: Kevin Townsend, Michael Durston, Douglas Sitch
  • Patent number: 10753745
    Abstract: 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: Grant
    Filed: January 26, 2016
    Date of Patent: August 25, 2020
    Assignee: ATLANTIC INERTIAL SYSTEMS LIMITED
    Inventors: Kevin Townsend, Andrew Clifford, Nicholas Wilkinson
  • Patent number: 10746564
    Abstract: 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: Grant
    Filed: August 5, 2016
    Date of Patent: August 18, 2020
    Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITED
    Inventor: Christopher Gregory
  • Patent number: 10731986
    Abstract: 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: Grant
    Filed: October 27, 2015
    Date of Patent: August 4, 2020
    Assignee: ATLANTIC INERTIAL SYSTEMS LIMITED
    Inventors: Kevin Townsend, Michael Durston
  • Patent number: 10670623
    Abstract: 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 in-plane 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: Grant
    Filed: August 11, 2016
    Date of Patent: June 2, 2020
    Assignee: Atlantic Inertial Systems Limited
    Inventors: Kiran Mysore Harish, Alan Malvern
  • Patent number: 10670400
    Abstract: 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 out-of-plane axis, induce a secondary cos n? resonance along a secondary axis at a secondary frequency fS. The gyroscope also includes digitally-controlled first and second sets to creating a static electrostatic balancing.
    Type: Grant
    Filed: September 27, 2018
    Date of Patent: June 2, 2020
    Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITED
    Inventors: Kevin Townsend, Andrew Kazer
  • Patent number: 10571485
    Abstract: 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: Grant
    Filed: June 5, 2015
    Date of Patent: February 25, 2020
    Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITED
    Inventors: Michael Durston, Kevin Townsend
  • Patent number: 10571271
    Abstract: 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 pseudo-measurement from stored expected flight data; provide said pseudo-measurement(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: Grant
    Filed: April 27, 2018
    Date of Patent: February 25, 2020
    Assignee: ATLANTIC INERTIAL SYSTEMS LIMITED
    Inventors: Nicholas Mark Faulkner, John Keith Sheard
  • Patent number: 10563987
    Abstract: 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 pseudo-velocity vector; provide the velocity vector and the pseudo-velocity 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 pseudo-velocity vector; and apply the roll gyro scale factor error from the Kalman filter as a correction to the output of the roll gyro.
    Type: Grant
    Filed: May 25, 2017
    Date of Patent: February 18, 2020
    Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITED
    Inventors: Nicholas M. Faulkner, John Keith Sheard
  • Patent number: 10539421
    Abstract: 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: Grant
    Filed: October 27, 2015
    Date of Patent: January 21, 2020
    Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITED
    Inventors: John Keith Sheard, Nicholas Mark Faulkner
  • Patent number: 10422811
    Abstract: A sensing structure for an accelerometer includes a support and a proof mass mounted to the support by flexible legs for in-plane 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: Grant
    Filed: February 16, 2015
    Date of Patent: September 24, 2019
    Assignee: ATLANTIC INERTIAL SYSTEMS, LIMITED
    Inventors: Alan Richard Malvern, Kiran Harish