Abstract: A Coriolis vibratory gyroscope having a resonator with at least a first and a second n=2 vibratory modes of same resonance frequency in a resonator plane; first and second sensing circuits for generating first and second sense signals in response to a motion of the resonator along a major axis of the first and second vibratory modes; a first drive circuit for driving the resonator in the first vibratory mode with a first drive signal; a second drive circuit for simultaneously driving the resonator in the second vibratory mode with a second drive signal; wherein said first signal has a first frequency equal to a resonant frequency of said resonator in said first vibratory mode, and said second signal has the same frequency as the first signal, modulated in amplitude with a second frequency.

Abstract: A microelectromechanical system (MEMS) gyroscope includes a driving mass and a driving circuit that operates to drive the driving mass in a mechanical oscillation at a resonant drive frequency. An oscillator generates a system clock that is independent of and asynchronous to the resonant drive frequency. A clock generator circuit outputs a first clock and a second clock that are derived from the system clock. The drive loop of the driving circuit including an analog-to-digital converter (ADC) circuit that is clocked by the first clock and a digital signal processing (DSP) circuit that is clocked by the second clock.

Abstract: Systems and methods for suppressing bias in a non-degenerate vibratory structure are provided. In certain embodiments, a vibratory structure includes a first proof mass; a second proof mass, wherein the first proof mass and the second proof mass are driven into motion along a first axis, wherein the first proof mass and the second proof mass move in anti-phase along a second axis, wherein the motion of the first proof mass and the second proof mass along the second axis is such that the centers of mass of the first proof mass and the second proof mass move collinearly along a same axis.

Abstract: A MEMS gyroscope comprises a first resonator with one or more first Coriolis element pairs, and a second resonator with one or more second Coriolis element pairs. The primary oscillation of these resonators is driven with the same drive signal, and a coupling arrangement between the first and second resonators synchronizes the primary oscillation of the one or more first Coriolis element pairs with the primary oscillation of the one or more second Coriolis element pairs. The coupling arrangement does not synchronize the secondary oscillation of the one or more first Coriolis element pairs with the secondary oscillation of the one or more second Coriolis element pairs. The secondary oscillations of the first and second electromechanical resonators are therefore independent of each other.

Abstract: Methods, apparatus, and systems for estimating and calibrating a gyroscope's scale using a magnetometer mounted on the same device by rotating the device about an axis multiple times; and, during the first rotation, storing the magnetometer magnetic field reading and a heading (from integration of the gyroscope readings) at each of a plurality of angular reference points; then, during each subsequent rotation, determining magnetometer/gyroscope-heading output pairs for which the magnetometer output matches the magnetometer reading corresponding to one of the reference points, thereby indicating that the device has reached the same heading as the matching reference point; then, for each matching output sample pair, using that magnetometer/gyroscope-heading output sample pair to update the gyroscope scale factor for the corresponding angular reference point; and averaging those scale estimates to generate a final gyroscope scale factor estimate.

Abstract: An in-situ calibration system, method and apparatus is disclosed that uses test electrodes to stimulate a proof-mass of a MEMS based gyroscope at a drive frequency as quasi-Coriolis forces to extract the electromechanical gain, and uses a non-resonant carrier signal on the proof-mass to extract the additional changes in the sense and drive capacitance. Additionally, an in-situ calibration system, method and apparatus is disclosed that uses quadrature electrodes to apply a known force stimulus to the proof-mass as part of a calibration procedure, where the known force is applied again after installation into a system or further into the life of the gyroscope. Differences in the proof-mass response to the force are proportional to changes in sensitivity, which allows the sensitivity to be corrected in-field.

Abstract: Disclosed is a magnetometer architecture that uses a separate shield to minimize cross-axis sensitivity with low impact on main axis sensitivity. In an embodiment, a magnetometer with cross-axis shielding comprises: a ring shield; a magnetic yoke disposed within the ring shield; and one or more magnetic field sensors disposed between the ring shield and the magnetic yoke, the magnetic field sensors positioned relative to the ring shield and the magnetic yoke such that flux induced by a magnetic field is absorbed in a cross-axis direction of the magnetometer.

Abstract: A method for correcting the driving amplitude of a gyro sensor, mainly comprises adjusting the size of a driving signal (a preset amplitude value) through feedback of a sensor response amplitude signal (an average amplitude value) in a resonance maintaining time period, so that the response amplitude of the resonance maintaining time period tends to be equal, and a stable resonance amplitude is maintained. Also provided is a system for correcting the driving amplitude of a gyro sensor.

Abstract: An embodiment of a gyroscope subsystem that is configured to reduce, or to eliminate, the effect of bias includes a gyroscope assembly, a calibration assembly, a determining circuit, and a bias-reducing circuit. The gyroscope assembly is configured to generate a gyroscope signal in response to a calibration angular velocity and another angular velocity about a sense axis, and the calibration assembly is configured to generate, about the sense axis, the calibration angular velocity. The determining circuit is configured to determine the other angular velocity in response to the gyroscope signal, and the bias-reducing circuit is configured to reduce a bias component of the determined other angular velocity in response to the gyroscope signal. For example, such a gyroscope subsystem can yield a value of an angular velocity having a bias component that is significantly less than the bias component of a value yielded by a conventional gyroscope subsystem.

Abstract: A method for correcting the driving amplitude of a gyro sensor, mainly comprises adjusting the size of a driving signal (a preset amplitude value) through feedback of a sensor response amplitude signal (an average amplitude value) in a resonance maintaining time period, so that the response amplitude of the resonance maintaining time period tends to be equal, and a stable resonance amplitude is maintained. Also provided is a system for correcting the driving amplitude of a gyro sensor.

Abstract: MEMS gyroscopes are often integrated in modern electronic products for measuring orientation or rotation in those products. However, these MEMS gyroscopes are often inaccurate. The invention provides a compensation circuit to compensate for errors causing a distortion of a measured Coriolis force. The compensation circuit demodulates an input signal provided by the MEMS gyroscope to produce a quadrature signal indicative of the quadrature error and provides a compensation signal to the MEMS gyroscope for actively compensating the quadrature error.

Abstract: One embodiment describes an inertial system. The system includes a gyroscope system comprising a plurality of gyroscopes. The gyroscope system can be configured to provide rotation rate data associated with rotation of the plurality of gyroscopes about a respective plurality of sensitive axes. The system also includes a rotation sensor system configured to calculate navigation data based on the rotation rate data. The rotation sensor system includes a self-calibration component configured to designate a first gyroscope of the plurality of gyroscopes for self-calibration during operation of the inertial system and to inject a calibration input signal into the first gyroscope. The self-calibration component being configured to calibrate the first gyroscope based on the rotation rate data of the first gyroscope corresponding to the calibration input signal relative to the rotation rate data associated with a remaining at least one of the plurality of gyroscopes.

Abstract: A gyroscope includes a substrate, a first structure, a second structure and a third structure elastically coupled to the substrate and movable along a first axis. The first and second structure are arranged at opposite sides of the third structure with respect to the first axis A driving system is configured to oscillate the first and second structure along the first axis in phase with one another and in phase opposition with the third structure. The first, second and third structure are provided with respective sets of sensing electrodes, configured to be displaced along a second axis perpendicular to the first axis in response to rotations of the substrate about a third axis perpendicular to the first axis and to the second axis.

Abstract: A circuit device includes a synchronization detection circuit which performs synchronization detection of a physical quantity signal of an input signal and outputs the physical quantity signal, and a filter unit. The synchronization detection circuit includes first and second detection circuits, and the filter unit includes first and second filters. In a first mode, the physical quantity signal from the first detection circuit is input to the first filter, and the undesired signal from the second detection circuit is input to the second filter. In a second mode, the physical quantity signal from the first detection circuit is input to the first filter and the second filter.

Abstract: A driver apparatus includes a vibrator and a drive circuit configured to input a drive signal to the vibrator to vibrate the vibrator. The drive circuit includes an output amplifier configured to output the drive signal to the vibrator based on a monitor signal, a power supply unit configured to supply a power supply voltage, and a power supply voltage controller configured to control the power supply voltage and to supply the controlled power supply voltage to the output amplifies. This driver apparatus can increase amplitude of the vibration of the vibrator, and can increase detection sensitivity to a physical quantity detection apparatus including the driver apparatus.

Abstract: A method of tuning a vibratory ring structure includes determining an angular spacing for a pair of fine tuning holes of substantially the same size, located on or near the neutral axis of the vibratory ring structure, 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 in the vibratory ring structure at the determined angular spacing. A ring structure, for example, a gyroscope, tuned or balanced in this manner, is also disclosed.

Abstract: One embodiment of the invention includes an inertial system. The system includes at least one inertial sensor configured to measure an inertial parameter associated with each of at least one axis. The system also includes a calibration system configured to sequentially measure an inertial calibration parameter at each of a plurality input axes. The system further includes an inertial processor configured to calculate motion of the inertial system based on the inertial parameter associated with each of the respective at least one axis and the sequential measurements of the inertial calibration parameter at each of the plurality of input axes.

Abstract: Methods and apparatus for calibrating a gyroscope without rotating the instrument. In one example, a calibration method includes operating the gyroscope in a self-oscillation loop to generate x-axis and y-axis drive signals, adding forcing signals to the x-axis and y-axis drive signals to produce pick-off x-axis and y-axis signals, measuring the pick-off x-axis and y-axis signals to produce measurement data, determining a relative phase between the pick-off x-axis and y-axis signals, based on the measurement data and the relative phase, estimating parameters of the gyroscope, based on the measurement data and the estimated parameters, calculating estimated position signals to calibrate the gyroscope.

Abstract: The present disclosure describes systems and methods for maintaining gyroscopic sensor accuracy over time and across changing environmental conditions. In certain aspects, the present disclosure provides arrangements and methods for calibrating a gyroscope while it is positioned on a robotic platform. In particular, the gyroscope may positioned on a sensor platform that is moved through a series of known or measured rotations and then the gyroscope signals are compared to reference data and the sensor's gain and offset calculated. In other aspects, the present disclosure provides arrangements and methods for utilizing measurements from multiple gyroscopes that measure the same axis of rotation.

Abstract: A method for real-time calibration of a gyroscope, configured for supplying a value of angular velocity that is function of a first angle of rotation about a first angular-sensing axis that includes defining a time interval, acquiring from an accelerometer an equivalent value of angular velocity that can be associated to the first angle of rotation; calculating a deviation between the value of angular velocity and the equivalent value of angular velocity; iteratively repeating the previous steps through the time interval, incrementing or decrementing an offset variable by a first predefined value on the basis of the values assumed by the deviations during the iterations, and updating the value of angular velocity as a function of the offset variable.

Abstract: A mechanism by which a MEMS gyroscope sensor can be calibrated using data gathered from other sensors in a system incorporating the MEMS gyroscope sensor is provided. Data gathered from an accelerometer and a magnetometer in fixed orientation relative to the gyroscope is used to calculate changes in orientation of a system. A constant acceleration vector measured by the accelerometer and a constant magnetic vector measured by the magnetometer are used as reference vectors in a solution to Wahba's problem to calculate a rotation matrix providing the system's orientation with respect to those two constant vectors. By comparing changes in orientation from one time to a next time, measured rates of angular change can be calculated. The measured rates of angular change can be used along with observed gyroscope rates of angular change as input to a linear regression algorithm, which can be used to compute gyroscope trim parameters.

Abstract: The invention relates to gyroscopic instruments. The method for calibrating the scale factor of an angular velocity sensor or an axisymmetric vibratory gyroscope, which method uses a control amplitude signal, a control precessional signal CP and a control quadrature signal CQ for exciting the vibration of a resonator on a resonant frequency, involves a first step of pre-calibration which consists of measuring and recording an initial scale factor and the value of an initial control signal, and a second step of measuring the value of the current control signal and establishing a scale factor SF that is corrected on the basis of a proportional relationship involving the initial scale factor SF°, the initial value of the control signal Y° and the current value of the control signal Y° according to the formula SF=SF°Y/Y°.

Abstract: In a gyroscopic system comprising at least four vibratory gyroscopes, a first measurement is provided by said vibratory gyroscope to be calibrated, and a second measurement is provided by a combination of the measurements from the other vibratory gyroscopes of the system. At the level of the vibratory gyroscope to be calibrated, an initial command is applied in order to command a change in position from a first vibration position (?1) to a second vibration position (?2). A calibrated scale factor value of the vibratory gyroscope to be calibrated is then determined on the basis of a calculated value in relation to the change in position, based on the period of time during which the initial command is applied, the initial command, an angular difference between the first and second vibration positions measured according to the first measurement and an angular difference between the first and second vibration positions measured according to the second measurement.

Abstract: A gyroscope having a resonant body utilizes a self-calibration mechanism that does not require physical rotation of the resonant body. Instead, interface circuitry applies a rotating electrostatic field to first and second drive electrodes simultaneously to excite both the drive and sense resonance modes of the gyroscope. When drive electrodes associated with both the drive and sense resonance modes of the gyroscope are excited by forces of equal amplitude but 90° phase difference, respectively, the phase shift in the gyroscope response, as measured by the current output of the sense electrodes for each resonance mode, is proportional to an equivalent gyroscope rotation rate.

Abstract: A method for calibrating a micro-electro-mechanical system (MEMS) vibrating structure gyroscope is provided. The method includes obtaining an indication of a position of at least one proof mass with respect to at least one drive electrode and applying an electrostatic force to the at least one proof mass as a function of the indication, the electrostatic force configured to position the at least one proof mass in a first position with respect to at least one drive electrode.

Abstract: The subject matter disclosed herein relates to the control and utilization of multiple sensors within a device. For an example, motion of a device may be detected in response to receipt of a signal from a first sensor disposed in the device, and a power state of a second sensor also disposed in the device may be changed in response to detected motion.

Abstract: A mobile device configured to be used in a wireless communication network includes: an image capture device; at least one sensor configured to measure a first orientation of the mobile device; and a processor communicatively coupled to the image capture device and the at least one sensor and configured to: identify an object in an image captured by the image capture device; use a position of the mobile device to determine an actual location of the object relative to the mobile device; and use the actual location of the object relative to the mobile device and the image to determine a correction for the sensor.

Abstract: A downhole sensor calibration apparatus includes a rotational or gimbaling mechanism for guiding a sensing axis of an orientation responsive sensor through a three-dimensional orbit about three orthogonal axes. A method includes using measurements taken over the three-dimensional orbit to calibrate the sensor and determine other characteristics of the sensor or tool.

Abstract: A personal mobile device housing contains a display screen, a wireless telephony communications transceiver, and a battery charger interface. A temperature sensor and a gyro sensor whose zero turn rate output contains an offset are also included. A lookup table has gyro zero turn rate offset correction values associated with different temperature values. A programmed processor accesses the lookup table to correct the output of the gyro sensor for zero turn rate offset. It is automatically determined, during in-the-field use, when the device is in a motionless state, and the output of the temperature and gyro sensors are read. The read gyro output is written to the lookup table as part of a pair of associated temperature and zero turn rate offset correction values. Other embodiments are also described and claimed.

Abstract: A method for calibrating a rotational angle sensor having a rotor (12) coupled to a rotating shaft (10) in a manner which is faithful to the rotational angle, a stator (16), and a scanning means (14) arranged on the stator (16). The scanning means (14) scans a material measure of the rotor (12) and generates measured angle values associated with the rotational angle position of the rotor (12). A laser gyroscope (18) measures the angular velocity of the shaft (10). The signals from the laser gyroscope (18) which are dependent on the angular velocity of the shaft (10) are integrated over time with respect to the rotational angle. The measured angle values from the scanning means (14) are compared with reference angle values, and correction variables are formed from the differences. During measurement of the rotational angle, the measured angle values are corrected using the correction variable.

Abstract: A self-test method by rotating the proof mass at a high frequency enables testing the functionality of both the drive and sense systems at the same time. In this method, the proof mass is rotated at a drive frequency. An input force which is substantially two times the drive frequency is applied to the actuation structures to rotate the proof mass of the gyroscope around the sensitive axis orthogonal to the drive axis. An output response of the gyroscope at the drive frequency is detected by a circuitry and a self-test response is obtained.

Abstract: In an apparatus for controlling an autonomous operating vehicle, a traveling direction and traveled distance are calculated based on outputs of wheel speed sensor and angular velocity sensor, and the vehicle is controlled to, as traveling straight, perform the operation using an operating machine in accordance with a predetermined travel pattern in a travel-scheduled area based on the calculated traveling direction and traveled distance. It is determined whether a difference between a scheduled-travel distance scheduled in the predetermined travel pattern and an actual traveled distance exceeds a permissible value when the vehicle is traveled straight and a center value of the outputs of the angular velocity sensor is corrected when the difference is determined to exceed the permissible value.

Abstract: A system and method for more accurately and robustly determining the heading of a vehicle by taking measurements of angle rates using rate sensors mounted on a movable mechanical assembly. In a quasi-static state of the vehicle, the mechanical assembly is rotated around axes perpendicular to the tangent plane of the Earth, and angle rates are measured by the rate sensors at different rotational angles of the mechanical assembly. The measurements of the angle rates are then computed to determine the initial heading of the vehicle relative to the true north of the Earth in the quasi-static state of the vehicle. After determining the initial heading, navigation state propagation is performed to determine the heading of the vehicle in non-quasi-static state of the vehicle. By taking measurements of the rate sensors at different rotation angles and performing computation, the heading of the vehicle relative to the Earth's true north can be determined using less accurate angle sensors.

Abstract: The present invention relates to a method for adjusting the resonant frequencies of a vibrating microelectromechanical (MEMS) device. In one embodiment, the present invention is a method for adjusting the resonant frequencies of a vibrating mass including the steps of patterning a surface of a device layer of the vibrating mass with a mask, etching the vibrating mass to define a structure of the vibrating mass, determining a first set of resonant frequencies of the vibrating mass, determining a mass removal amount of the vibrating mass and a mass removal location of the vibrating mass to obtain a second set of resonant frequencies of the vibrating mass, removing the mask at the mass removal location, and etching the vibrating mass to remove the mass removal amount of the vibrating mass at the mass removal location of the vibrating mass.

Abstract: The present invention relates to a method for adjusting the resonant frequencies of a vibrating microelectromechanical (MEMS) device. In one embodiment, the present invention is a method for adjusting the resonant frequencies of a vibrating mass including the steps of patterning a surface of a device layer of the vibrating mass with a mask, etching the vibrating mass to define a structure of the vibrating mass, determining a first set of resonant frequencies of the vibrating mass, determining a mass removal amount of the vibrating mass and a mass removal location of the vibrating mass to obtain a second set of resonant frequencies of the vibrating mass, removing the mask at the mass removal location, and etching the vibrating mass to remove the mass removal amount of the vibrating mass at the mass removal location of the vibrating mass.

Abstract: Disclosed herein are a gyro sensor offset automatic correcting circuit, a gyro sensor system, and a method for automatically correcting offset of a gyro sensor. There is provided a gyro sensor offset automatic correcting circuit, including: a signal gain controller receiving and amplifying output signals of each sensor electrode, while removing at least some of offset by a driving signal component included in each output signal by controlling a variable resistor(s); and an amplitude detector detecting the output signal of the signal gain controller to control the variable resistor(s) so that the output signal of the signal gain controller is maintained within a predetermined range. Further, there are provided a gyro sensor system including the gyro sensor offset automatic correcting circuit and a method for automatically correcting offset of a gyro sensor.

Abstract: A gyroscope having a resonant body utilizes a self-calibration mechanism that does not require physical rotation of the resonant body. Instead, interface circuitry applies a rotating electrostatic field to first and second drive electrodes simultaneously to excite both the drive and sense resonance modes of the gyroscope. When drive electrodes associated with both the drive and sense resonance modes of the gyroscope are excited by forces of equal amplitude but 90° phase difference, respectively, the phase shift in the gyroscope response, as measured by the current output of the sense electrodes for each resonance mode, is proportional to an equivalent gyroscope rotation rate.

Abstract: Aspects of the disclosure relate to computing technologies. In particular, aspects of the disclosure relate to mobile computing device technologies, such as systems, methods, apparatuses, and computer-readable media for improving calibration data by increasing the diversity of orientations used for generating the calibration data. In one embodiment, the computing device receives a plurality of calibration measurements associated with one or more sensors of a device, determines a degree to which the plurality of calibration measurements were captured at different orientations of the device, and determines, based on the degree, whether to update one or more calibration parameters.

Abstract: A gyroscopic system comprises at least four vibratory gyroscopes capable of changing vibration position. A first measurement is provided by a gyroscope to be calibrated and a second measurement is provided by a combination of the respective measurements from the other gyroscopes of the system, these first and second measurements being carried out along the same measurement axis. The determination (12) of a measurement drift value between the first measurement and the second measurement is followed by a command (13) to change the vibration position of the gyroscope to be calibrated to another vibration position and a drift value is again determined. The vibration position change command and the determination of a drift value are repeated (14) K times, K being a positive integer. Then, a drift model is generated (15) as a function of the vibration position of the gyroscope to be calibrated on the basis of the drift values obtained.

Abstract: Detecting and/or mitigating the presence of particle contaminants in a MEMS device involves including MEMS structures that in normal operation are robust against the presence of particles but which can be made sensitive to that presence during a test mode prior to use, e.g.

Abstract: The present invention proposes a single-axis-control-input gyroscope system having imperfection compensation, which comprises a gyroscope and a state observer. The gyroscope includes a mechanical structure, and the dynamic behavior of the mechanical structure is described with a plurality of system parameters and a plurality of dynamic equations. The system parameters include a mass of the gyroscope, two main-axis spring constants, a cross-axis spring constant, two main-axis damping coefficients, a cross-axis damping coefficient and an angular velocity. The mechanical imperfections cause the system parameters to deviate from the designed values and become unknown values. The gyroscope receives a single-axis control signal and outputs a plurality of gyroscopic system dynamics. The single-axis control signal includes at least two frequency signals. The state observer is coupled to the gyroscope to receive the gyroscopic system dynamics as the inputs thereof to feed back compensations to the state observer.

Abstract: Embodiments of the invention provide a blending filter based on extended Kalman filter (EKF), which optimally integrates the IMU navigation data with all other satellite measurements tightly-coupled integration filter. This blending filter can be easily implemented with minor modification to the position engine of stand-alone GNSS receiver. Provided is a low-complexity tightly-coupled integration filter for sensor-assisted global navigation satellite system (GNSS) receiver. The inertial measurement unit (IMU) contains inertial sensors such as accelerometer, magnetometer, and/or gyroscopes Embodiments also include method for pedestrian dead reckoning (PDR) data conversion for ease of GNSS/PDR integration. The PDR position data is converted to user velocity measured at the time instances where GNSS position/velocity estimates are available.

Abstract: A microelectromechanical gyroscope having a supporting structure; a mass capacitively coupled to the supporting structure and movable with a first degree of freedom and a second degree of freedom, in response to rotations of the supporting structure about an axis; driving components, for keeping the mass in oscillation according to the first degree of freedom; a read interface for detecting transduction signals indicating the capacitive coupling between the mass and the supporting structure; and capacitive compensation modules for modifying the capacitive coupling between the mass and the supporting structure. Calibration components detect systematic errors from the transduction signals and modify the capacitive compensation modules as a function of the transduction signals so as to attenuate the systematic errors.

Abstract: A gyroscopic system provides measurements on the basis of a vibrating gyroscope and provides a measurement signal. A periodic control signal is applied to it; in order to rotate the position of vibration, during a half period, according to a first speed profile, from a first up to a second position; and in order to rotate the position of vibration in an opposite direction during the other part of the period, according to a second speed profile, up to a third position. The measurements are based on corrected signals, each of said corrected signals, respectively for each of the vibrating gyroscopes, being obtained by; deducting the control signal from the measurement signal of the vibrating gyroscope; and taking account of errors identified on the basis of a comparison, of the measurements provided by the gyroscopic system as a function of the position of vibration with reference measurements.

Abstract: A method for calibrating a gyratory compactor apparatus is provided. The gyratory compactor apparatus is of the type being configured to compact and impart an orbital motion to a sample in a mold that defines a mold axis and includes at least one actuator for imparting lateral displacement of the mold relative to a longitudinal axis of the gyratory compactor apparatus. The method includes the steps of imparting lateral orbital displacement of the mold relative to the gyratory compactor apparatus by actuation of the at least one actuator to thereby define a gyratory angle between the gyratory compactor apparatus and the mold axis, measuring the gyratory angle, and determining adjustments to actuation of the at least one actuator based on the measured gyratory angle and a target angle. An associated apparatus and method for calibrating the apparatus are also included.

Abstract: The present invention relates to a method for adjusting the resonant frequencies of a vibrating microelectromechanical (MEMS) device. In one embodiment, the present invention is a method for adjusting the resonant frequencies of a vibrating mass including the steps of patterning a surface of a device layer of the vibrating mass with a mask, etching the vibrating mass to define a structure of the vibrating mass, determining a first set of resonant frequencies of the vibrating mass, determining a mass removal amount of the vibrating mass and a mass removal location of the vibrating mass to obtain a second set of resonant frequencies of the vibrating mass, removing the mask at the mass removal location, and etching the vibrating mass to remove the mass removal amount of the vibrating mass at the mass removal location of the vibrating mass.

Abstract: Techniques for estimating compass and gyroscope biases for handheld devices are disclosed. The compass bias can be determined by causing a small movement of the handheld device and comparing the data obtained from the compass with the data obtained from the gyroscope. The gyroscope bias can be determined by obtaining a quaternion based angular velocity term of the handheld device when the accelerometer and compass data are reliable, and then comparing the angular velocity term with the gyro data to estimate the gyro bias. When the compass and/or the accelerometer data are unreliable, a previously determined quaternion angular velocity term is used. The gyroscope bias can also be determined by measuring gyroscope biases at various temperatures in a non-factory setting, storing the data in a memory, and using the data to estimate gyro biases when the accelerometer and/or the compass data are unreliable.

Abstract: A system for correcting angular velocity measurements from a gyroscope and using the corrected angular velocity measurements to position an antenna used with a vehicle. The system determines an approximate null point voltage of a gyroscope of the type that produces a voltage related to an angular velocity to be measured by the gyroscope. The approximate null point is determined by sampling the output voltage to obtain a plurality of sampled voltages and choosing an approximate mode of the plurality of sampled voltages as the approximate null point voltage.

Abstract: Methods and systems for compensating for gyroscopic errors. A system uses magnetometers to detect and measure a magnetic field local to a personal navigation device. When the local magnetic field is quasi-static, the rate of change of the magnetic field is combined with the rotational rate of change of the device. This generates an estimated gyroscope error. The error can then be used to correct for time-varying inherent gyroscope errors.

Abstract: A test auxiliary device for testing a portable data terminal having a plurality of sensors includes a base, a carrying unit, a driving unit, and a controlling unit. The carrying unit is disposed on the base and includes a carrying platform and a carrying base. The carrying platform and the carrying base form a first angle and a second angle with the base, respectively, and thereby together form a compound slope. The driving unit drives the carrying unit to move, allowing the carrying platform to move with acceleration and at an angular velocity. The controlling unit receives sensing values generated by the sensors, respectively. The test auxiliary device further includes a test matching unit for testing the sensors in operation. Accordingly, the test auxiliary device assists users in determining whether the sensors of the portable data terminal are functioning well.