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.

IPC Classes  ?

• G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
• G01P 21/00 - Testing or calibrating of apparatus or devices covered by the other groups of this subclass
• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation

Abstract

A capacitive accelerometer (202) comprises: a substantially planar proof mass (204) mounted to a fixed substrate by flexible support legs (250) so as to be linearly moveable in an in-plane sensing direction (200). 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 (221, 222). A set of moveable damping fingers (224) extend from the proof mass substantially perpendicular to the sensing direction, laterally spaced in the sensing direction. A set of fixed damping fingers (222) mounted to the fixed substrate interdigitates with the set of moveable damping fingers and comprises an electrical connection (260) to the proof mass so that the interdigitated damping fingers (228, 230) are electrically common. The damping fingers are mounted in a gaseous medium that provides a damping effect.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values
• B81B 5/00 - Devices comprising elements which are movable in relation to each other, e.g. comprising slidable or rotatable elements

Abstract

An angular velocity sensor comprises: an insulative support layer (10); a substrate layer (8) formed of a silica-based material and comprising a planar ring structure (2) mounted to vibrate in-plane; and a plurality of conductive electrodes (14), each comprising a first set of moveable conductive electrode tracks (14a) formed on a surface of the planar ring and a second set of fixed conductive electrode tracks (14b) formed on a surface of the insulative support layer axially spaced from the surface of the planar ring. The first and second sets of conductive electrode tracks are interdigitated with a lateral spacing between them in a radial direction. Each moveable conductive electrode track has a radial offset from a median line between adjacent fixed conductive electrode tracks such that each moveable conductive electrode track has a different lateral spacing from two different adjacent fixed conductive electrode tracks in opposite radial directions.

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

A mounting system for mounting an electronic component (2) in a housing (8) comprises a visco-elastic damping element (14, 20) for damping the transmission of vibration from the housing (8) to the component (2) in use, and a support (24, 52) for supporting the component (2) in the housing (8) independently of the damping element (14, 20) whereby the weight of the component (2) is substantially or completely removed from the damping element (14, 20). The support (24, 52) is configured to be selectively releasable from the component (2) such that the component (2) is then supported only by the damping element (14, 20).

IPC Classes  ?

• F42B 15/08 - Self-propelled projectiles or missiles, e.g. rockets; Guided missiles for carrying measuring instruments
• F42B 30/00 - Projectiles or missiles, not otherwise provided for, characterised by the ammunition class or type, e.g. by the launching apparatus or weapon used

Abstract

An assembly (2) for attachment to a projectile comprises a first part (4) and a second part (6) mounted for rotation relative to the first part (4) about an axis (A). There is an axial gap (G) between the first and second parts (4, 6). At least one plastically deformable element (34) is arranged within the gap (G) between the first and second parts (4, 6), the plastically deformable element (34) being such as to deform due to the closing of the axial gap (G) between the first and second parts (4, 6) during launch of the projectile.

IPC Classes  ?

• F42B 10/26 - Stabilising arrangements using spin
• F42C 19/02 - Fuze bodies; Fuze housings

Abstract

A method of compensating for signal error is described, comprising: receiving a first signal from a first sensor, said first signal indicative of a movement characteristic; applying an error compensation to said first signal to produce an output signal; applying a variable gain factor to said error compensation; receiving a second signal from a second sensor indicative of said movement characteristic; wherein said error compensation is calculated using the difference between said output signal and said second signal, and said variable gain factor is calculated using said first signal.

IPC Classes  ?

• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass

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.

IPC Classes  ?

• G01C 19/5776 - Signal processing not specific to any of the devices covered by groups

Abstract

A successive approximation Analogue to Digital Converter (ADC), comprising: a sample and hold device arranged to sample and hold an input signal at the beginning of a conversion cycle; a successive approximation register that sequentially builds up a digital output from its most significant bit to its least significant bit; a digital to analogue converter that outputs a signal based on the output of the successive approximation register; a comparator that compares the output of the digital to analogue converter with an output of the sample and hold device and supplies its output to the successive approximation register; and a residual signal storage device arranged to store the residual signal at the end of a conversion cycle; and wherein the successive approximation ADC is arranged to add the stored residual signal from the residual signal storage device to the input signal stored on the sample and hold device at the start of each conversion cycle. After each ADC full conversion by the SAR, the analogue conversion of the digital output is as close to the original input signal as the resolution will allow. However there remains the residual part of the input signal that is smaller than what can be represented by the least significant bit of the digital output of the SAR. In normal operation, successive outputs of a SAR for the same input will result in the same digital value output and the same residual. By storing the residual at the end of each conversion and adding the residual onto the input signal of the next conversion the residuals are accumulated over time so that they may affect the output digital value. After a number of conversions, the accumulated residuals add up to more than the value represented by the LSB of the register and the digital value will be one higher than if a conversion had been performed on the input signal alone. In this way, the residual signal affects the output value in time and thus can be taken into account by processing the digital output in the time domain.

IPC Classes  ?

• H03M 1/06 - Continuously compensating for, or preventing, undesired influence of physical parameters
• H03M 1/46 - Analogue value compared with reference values sequentially only, e.g. successive approximation type with digital/analogue converter for supplying reference values to converter

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. The system further comprises a controller (225, 250), arranged: - to compute a current projectile attitude from the outputs of the first, second and third gyros, the computed attitude comprising a roll angle, a pitch angle and a yaw angle; - for at least two time points, to compare the computed pitch and yaw angles with expected values for the pitch and yaw angles; - for each of said at least two time points, to calculate a roll angle error based on the difference between the computed pitch and yaw angles and the expected pitch and yaw angles; - to calculate a roll angle error difference between said at least two time points; - to calculate the total roll angle subtended between said at least two time points; - to calculate a roll angle scale factor error based on said computed roll angle error difference and said total subtended roll angle and apply the calculated roll angle scale factor error to the output of the roll gyro.

IPC Classes  ?

• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• G01C 25/00 - Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
• F41G 7/36 - Direction control systems for self-propelled missiles based on predetermined target position data using inertial references
• F42B 15/01 - Arrangements thereon for guidance or control
• G05D 1/10 - Simultaneous control of position or course in three dimensions

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.

IPC Classes  ?

• G01C 19/5776 - Signal processing not specific to any of the devices covered by groups
• H03L 7/08 - Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop - Details of the phase-locked loop

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 V 2 '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.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

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).

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position
• G01P 21/00 - Testing or calibrating of apparatus or devices covered by the other groups of this subclass
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Abstract

A method for closed loop operation of a capacitive accelerometer comprising: a proof mass; first and second sets of both fixed and moveable capacitive electrode fingers, interdigitated with each other; the method comprising: applying PWM drive signals to the fixed fingers; sensing displacement of the proof mass and changing the mark:space ratio of the PWM drive signals, to provide a restoring force on the proof mass that balances the inertial force of the applied acceleration and maintains the proof mass at a null position; detecting when the mark:space ratio for the null position is beyond a predetermined upper or lower threshold; and further modulating the PWM drive signals by extending or reducing x pulses in every y cycles, where x>l and y>l, to provide an average mark:space ratio beyond the upper or lower threshold without further increasing or decreasing the mark length of the other pulses.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values
• G01P 21/00 - Testing or calibrating of apparatus or devices covered by the other groups of this subclass

Abstract

An inertial measurement system 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; a controller, arranged to: compute a current projectile attitude from the outputs of the first, second and third gyros, the computed attitude comprising a roll angle, a pitch angle and a yaw angle; compare the computed pitch and yaw angles with expected values for the pitch and yaw angles;calculate a roll angle error and a roll scale factor error based on the difference between the computed pitch and yaw angles and the expected pitch and yaw angles; and apply the calculated roll angle error and roll scale factor error to the output of the roll gyro. Calculating both roll angle error and roll scale factor error as corrections in the inertial measurement system allows much better control and correction of the calculated roll angle from the roll gyroscope even at high roll rates (e.g. 10-20 rotations per second). This correction system compensates for the large errors that can arise in inexpensive gyroscopes and therefore allows an accurate navigational system to be built with inexpensive components. No additional attitude sensors such as magnetometers are required, again reducing the cost and complexity of the system.

IPC Classes  ?

• G01C 19/02 - Rotary gyroscopes
• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• G05D 1/10 - Simultaneous control of position or course in three dimensions

Abstract

A sensing structure for an accelerometer, comprising: a proof mass mounted to a support by flexible legs for in-plane movement in response to an applied acceleration along a sensing direction; the proof mass comprising a plurality of moveable electrode fingers extending substantially perpendicular to and spaced apart in the sensing direction; at least one pair of fixed capacitor electrodes comprising first and second sets of fixed electrode fingers extending substantially perpendicular to and spaced apart in the sensing direction; the first and second sets of fixed electrode fingers interdigitate with the moveable electrode fingers with a first and second offset in one direction and in the opposite direction, respectively, from a median line therebetween; wherein the proof mass is an outer frame surrounding the fixed capacitor electrodes, the flexible legs extending laterally inwardly from the proof mass to a central anchor.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Abstract

A capacitive accelerometer including: at least one additional fixed capacitor electrode with a plurality of additional fixed capacitive electrode fingers extending along the sensing direction. The proof mass comprises a plurality of moveable capacitive electrode fingers extending from the proof mass along the sensing direction and arranged to interdigitate with the plurality of additional fixed capacitive electrode fingers of the at least one additional fixed capacitor electrode. A means is provided for applying a voltage to the at least one additional fixed capacitor electrode to apply an electrostatic force to the plurality of moveable capacitive electrode fingers that acts to pull the proof mass towards the at least one further fixed capacitor electrode and thereby reduces the lateral spacings between the movable capacitive electrode fingers of the proof mass and the first and second sets of fixed capacitive electrode fingers that provide electrostatic forces for sensing purposes.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values
• B81B 5/00 - Devices comprising elements which are movable in relation to each other, e.g. comprising slidable or rotatable elements
• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position

Abstract

A closed loop method of controlling a capacitive accelerometer (1) uses two servo loops. A Vcrit servo loop (32) uses an output signal (S2) modulated by a sine wave signal (S1). The Vcrit control signal adjusts the magnitude of the PWM drive signals applied to the fixed capacitor electrodes of the accelerometer (1), thereby optimising open loop gain.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/13 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by measuring the force required to restore a proofmass subjected to inertial forces to a null position
• G01P 15/08 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values

Abstract

A vibratory ring structure is described which comprises a ring body and at least one ring electrode secured thereto, the or each ring electrode extending over a first angular extent and: being attached to the ring body over second angular extent, wherein the first angular extent is greater than the second angular extent.

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

A method of tuning a vibratory ring structure is described which comprises determining an angular spacing for a pair of fine tuning holes (16) of substantially the same size, located on or near the neutral axis of the vibratory ring structure (10), the angular offset being selected to reduce to an acceptable level the frequency split between the target normal mode and a further normal mode which Is angularly offset relative to the target normal mode, and forming the pair of fine tuning holes (16) in the vibratory ring structure (10) at the determined angular spacing, A ring structure, for example a gyroscope, tuned or balanced in this manner is also disclosed.

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

A sensor comprises a substrate (16) and a sensor element (20) anchored to the substrate (16), the substrate (16) and sensor element (20) being of dissimilar materials and having different coefficients of thermal expansion, the sensor element (20) and substrate (16) each having a generally planar face arranged substantially parallel to one another, the sensor further comprising a spacer (26), the spacer (26) being located so as to space at least part of the sensor element (20) from at least part of the substrate (16), wherein the spacer (26) is of considerably smaller area than the area of the smaller of face of the substrate (16) and that of the sensor element (20).

IPC Classes  ?

• B81B 7/00 - Microstructural systems
• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

An electronic device comprises a circuit substrate, and a moulded interconnect device incorporating integral legs to mount the interconnect device upon the substrate, the legs spacing at least part of the interconnect device from the substrate, at least one of the legs carrying a conducting track to provide an electrical interconnection between the interconnect device and the substrate.

IPC Classes  ?

• G01C 21/16 - Navigation; Navigational instruments not provided for in groups by using measurement of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
• G01S 19/35 - Constructional details or hardware or software details of the signal processing chain
• H05K 1/14 - Structural association of two or more printed circuits

Abstract

A vibratory gyroscope is provided comprising a plurality of secondary pickoff transducers which are each sensitive to the secondary response mode, wherein: at least two of the secondary pickoff transducers comprise skew transducers designed to be sensitive to the primary mode which produce an induced quadrature signal in response thereto. A method of using the gyroscope is provided comprising the steps of arranging electrical connections between the secondary pickoff transducers and a pickoff amplifier so that in use the induced quadrature signal is substantially rejected by the amplifier in the absence of a fault condition, and the amplifier outputs an induced quadrature signal when a fault condition disconnects one of the skew transducers from the amplifier, and a comparator compares the quadrature output from the pickoff amplifier with a predetermined threshold value and provides a fault indication when the predetermined threshold is exceeded.

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

An accelerometer comprises a support (12), a proof mass (14) supported for movement relative to the support (12) by a plurality of mounting legs (16), a plurality of fixed capacitor fingers associated with the support (12) and a plurality of movable capacitor fingers associated with the proof mass (14), the fixed capacitor fingers being interdigitated with the movable capacitor fingers, the mounting legs (16) being of serpentine shape, each mounting leg (16) comprising at least a first generally straight section (16a), a second generally straight section (16a), and an end section (16b) of generally U-shaped form interconnecting the first and second generally straight sections (16a), wherein the thickness Te of the end section (16b) is greater than the thickness Tc of a central part (16c) of both of the first and second generally straight sections (16a).

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up

Abstract

An accelerometer comprises a support, a first mass element and a second mass element, the mass elements being rigidly interconnected to form a unitary movable proof mass, the support being located at least in part between the first and second mass elements, a plurality of mounting legs securing the mass elements to the support member, at least two groups of movable capacitor fingers provided on the first mass element and interdigitated with corresponding groups of fixed capacitor fingers associated with the support, and at least two groups of movable capacitor fingers provided on the second mass element and interdigitated with corresponding groups of fixed capacitor fingers associated with the support.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up
• G01P 15/18 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration in two or more dimensions

Abstract

A silicon MEMS gyroscope is described having a ring or hoop-shaped resonator (1). The resonator (1) is formed by a Deep Reactive Ion Etch technique and is formed with slots (5) extending around the circumference of the resonator (1) on either side of the neutral axis (4) of the resonator (1). The slots (5) improve the Quality Factor Q of the gyroscope without affecting the resonant frequency of the resonator.

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

An accelerometer open loop control system comprising a variable capacitance accelerometer having a proof mass movable between fixed capacitor plates, drive signals applied to the capacitor plates, a charge amplifier amplifying an accelerometer output signal representing applied acceleration, and an autoranging facility for monitoring the output signal, and for adjusting the drive signals in dependence on the output signal in order to restrict the amplitude of the accelerometer output signal, thus maintaining sensitivity of the accelerometer while permitting response to a wide range of g values. Corrections are applied by means of look up tables to compensate for inaccuracies arising from movement of the proof mass and temperature variations.

IPC Classes  ?

• G01P 15/125 - Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces with conversion into electric or magnetic values by capacitive pick-up

Abstract

A vibrating structure gyroscope includes a ring structure (52), an external frame (58) and a flexible support (56e) including a pair of symmetrical compliant legs (60a, 60b) arranged to retain the ring structure (52) within the external frame (58). Metal track (80) is provided on an upper surface of the ring structure (52), the compliant legs (60a, 60b) and the external frame (58), over an insulating surface oxide layer, not illustrated. Each flexible support (56e) is arranged to carry metal track (80) associated with a single drive or pick- off transducer. The metal track (80) is repeated for eight circuits, one circuit for each transducer. Each circuit of metal track (80) associated with a transducer begins at a first bond-pad (82) on the external frame (58), runs along a first compliant leg (60a), across an eighth segment (84) of the ring structure (52) and back along the other compliant leg (60b) to a second bond-pad 86 on the external frame (58).

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

A gyroscope has a ring (70) and a primary drive transducer (72) for oscillating the ring (70) substantially at the resonant frequency in a primary mode. A primary control loop receives primary pick-off signals from the primary pick-off transducer (74) and provides primary drive signals 116 to the primary drive transducer (72) so as to maintain resonant oscillation of the ring (70). The primary control loop includes a demodulator (78) determining the amplitude of the fundamental frequency of the primary pick-off signals and a demodulator (82) determining the amplitude of the second harmonic frequency of the primary pick-off signals and a drive signal generator (100, 106, 110 and 114) producing the primary drive signals (116) with an amplitude that is dependent on a ratio of the amplitude of the second harmonic frequency of the primary pick-off signal over the amplitude of the fundamental frequency of the primary pick-off signal as derived by a divider (100).

IPC Classes  ?

• G01C 19/5677 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators

Abstract

A gyroscope structure (41) includes ring structure (42) supported from a central hub (43) by eight compliant support legs (44a to 44h). Primary drive transducers (45a and 45b) and secondary drive transducers (46a and 46b) are all located around and in spaced relationship with the external periphery of the ring structure (42) to create capacitive gaps and primary pick-off transducers (47a and 47b) and secondary pick-off transducers (48a and 48b) are all located around and (10) in spaced relationship with the internal periphery of the ring structure (42) to create capacitive gaps. The gyroscope structure (41) includes sixteen capacitor plates (49a to 49p) in spaced relationship to the ring structure (42) to create capacitive gaps. Two groups of capacitive plates (49a to 49d and 49i to 49l) are all located around the internal periphery of the ring structure (42) and two groups of capacitor plates (49e to 49h and 49m to 49p) are all located around the external periphery of the ring structure (42). Each capacitor plate (49a to 49p) is arranged to generate a predetermined electrostatic force, which acts upon the ring structure (42) to locally adjust the stiffness of the ring structure 42. The positioning of the transducers (45a to 48b) and capacitor plates (49a to 20 49p) reduces the effect of variation a capacitive gap with ring structure (42) due to temperature change, thereby improving the scalefactor of the gyroscope structure.

IPC Classes  ?

• G01C 19/5684 - Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially two-dimensional vibrators, e.g. ring-shaped vibrators the devices involving a micromechanical structure

Abstract

A terrain mapping apparatus (1 ) carried by an aircraft is arranged to receive height data from a terrain elevation data array memory (7), to determine the correlation between elements of the terrain elevation data array memory (7)and detected height data stored in elements of a laser obstacle detector co-ordinate frame memory (4). The height data of the laser obstacle detector co-ordinate frame memory being provided by a laser obstacle detector (3) monitoring terrain overflown by the aircraft. Updated height data, determined by a mapping processor (5) for each element of the terrain elevation data array memory (7) is provided from height data associated with a predetermined number, typically four, surrounding elements of the laser obstacle detector co-ordinate frame memory (4) and updated height data is then stored in a digital elevation array memory (8).

IPC Classes  ?

• G01S 17/89 - Lidar systems, specially adapted for specific applications for mapping or imaging
• G01S 17/93 - Lidar systems, specially adapted for specific applications for anti-collision purposes
• G01C 21/00 - Navigation; Navigational instruments not provided for in groups