128 results about "Specific force" patented technology

The present invention discloses a structural and mechanical model and modeling methods for human bone based on bone's hierarchical structure and on its hierarchical mechanical behavior. The model allows for the assessment of bone deformations, computation of strains and stresses due to the specific forces acting on bone during function, and contemplates forces that do or do not cause viscous effects and forces that cause either elastic or plastic bone deformation.

In one preferred embodiment, the present invention provide a navigation system for a movable platform comprising a GNSS receiver sensor for providing position signals representative of the estimated current position of the movable platform; a camera sensor for providing photographic images representative of the surroundings of the movable platform; and an IMU (Inertial Measurement Unit) sensor for providing specific force and angular rate signals representative of the current specific forces and rate of the movable platform. A processor is responsive to the camera photographic images to estimate the position and attitude of the movable platform, the covariance of the position and attitude estimates and the covariance of consecutive position and attitude estimates. The processor is responsive to the GNSS receiver's estimated position signal, the camera's estimated position and attitude signal, the camera's estimated position and attitude covariance, the camera's estimated correlation of the covariance of consecutive position and attitude estimates, and the specific force and angular rate signals, for providing a navigation solution representative of the estimated current position, velocity, and attitude of the movable platform.

The present invention relates to a z-axial solid-state gyroscope. Its main configuration is manufactured with a conductive material and includes two sets of a proof mass and two driver bodies suspended between two plates by an elastic beam assembly. Both surfaces of the driver bodies and the proof masses respectively include a number of grooves respectively perpendicular to a first axis and a second axis. The surfaces of the driver bodies and the proof masses and the corresponding stripe electrodes of the plates thereof are respectively formed a driving capacitors and a sensing capacitors. The driving capacitor drives the proof masses to vibrate in the opposite direction along the first axis. If a z-axial angular velocity input, a Coriolis force makes the two masses vibrate in the opposite direction along the second axis. If a first axial acceleration input, a specific force makes the two masses move in the same direction along the first axis. If a second axial acceleration input, a specific force makes the two masses move in the same direction along the second axis. Both inertial forces make the sensing capacitances change. One z-axial solid-state gyroscopes and two in-plane axial gyroscopes can be designed on a single chip to form a complete three-axis inertial measurement unit.

The invention discloses a CKF filtering-based vehicle dynamic model auxiliary inertial navigation combined navigation method. The CKF filtering-based vehicle dynamic model auxiliary inertial navigation combined navigation method comprises the following steps: calculating posture, speed and position of a vehicle according to angle increment and specific force output by a micro-inertia device and by an inertial navigation numerical value updating algorithm; establishing a three-degree-of-freedom vehicle dynamic model, and calculating the speed of a carrier by taking a steering wheel angle and a longitudinal force as control input quantity and by a fourth order Ronge-Kutta method in real time; designing a CKF filter by taking an inertial navigation equation as a state equation and speed difference between a dynamical model and inertial navigation calculation to perform state estimation on a combined navigation system; performing output correction on strapdown inertial navigation calculation result by the position the speed and the posture error obtained by CKF estimation, and performing feedback correction on the inertial navigation through peg-top and adding error. The method aims at the problems that the inertial navigation error is accumulated along with time and navigation precision cannot be maintained for a long time, and the accuracy and the reliability of a vehicle navigation system can be improved.

The invention provides a method for obtaining an inertial navigation system attitude based on a DGPS (differential global positioning system). The method comprises the following steps: measuring the acceleration of a carrier through the DGPS and obtaining a measured value of acceleration through low pass filtering; obtaining a gravity vector expressed in a geographical system according to a calculating equation of the inertial navigation system under the condition that specific force information and the acceleration of the carrier are known; determining the conversion matrix of an inertial system to the geographical system by using longitude and latitude information and initial longitude information provided by DGPS, and converting the gravity vector expressed in the geographical system to a gravity vector expressed in the inertial system to obtain the gravity vector expressed in the inertial system; calculating the drifting angel and latitude of the gravity vector using the gravity vector of an inertial space; obtaining a conversion matrix C_i^n after twice coordinate conversions; in the inertial navigation system, collecting angular rate signals using a gyroscope, calculating a rotating vector, updating a quaternion and updating C_b^i through the quaternion; determining an attitude conversion matrix of the system according to C_i^n and C_b^i to obtain the heading and attitude angle of the carrier, so that the accuracy of the attitude information is guaranteed to meet the requirement of ship navigation.

The invention relates to a rapid online dynamic calibration method for the zero offset of a GNSS auxiliary MEMS inertial sensor. The MEMS inertial sensor comprises an MEMS accelerometer and an MEMS gyroscope which form an MEMS inertia measurement unit; in a GNSS/MEMS INS combined navigation system, the zero offset of the accelerometer is calibrated in real time through carrying out online comparison on the modulus of a total specific force obtained by GNSS deduction and the modulus of a total specific force output by the MEMS accelerometer; the zero offset of the gyroscope calibrated in real time through deducting attitude information online by utilizing speed information measured by a GNSS and adding the dynamic or static constraint of the uniform motion or the approximate uniform linearmotion. The invention has the advantages that the method is not limited by the motion state of a carrier, has small calculated amount and strong real-time performance, can rapidly complete the onlinedynamic calibration of the zero offset of the inertial sensor and is beneficial to realizing the rapid starting of the GNSS/MEMS INS combined system and the batch application thereof.

The invention discloses a ship large azimuth misalignment angle transfer alignment method based on volumetric Kalman filtering. The ship large azimuth misalignment angle transfer alignment method comprises the following steps: firstly, converting a specific force output of a secondary inertial navigation accelerometer to a navigation coordinate system; carrying out filtering processing on the specific force by utilizing a Butterworth digital low-pass filter; secondly, carrying out inertial navigation calculation on primary and secondary inertial navigation respectively; transmitting speed, posture and angular speed information of the primary inertial navigation to a navigation computer of the secondary inertial navigation; constructing measurement by utilizing speed error, posture error and angular speed error between primary and secondary inertial navigation system; then establishing a state equation and a measurement equation under a large azimuth misalignment angle condition by adopting a matching manner of a speed, a posture and an angular speed; finally, carrying out volumetric Kalamn filtering calculation by utilizing the established state equation and measurement equation and estimating a mounting error angle between the secondary inertial navigation system and the primary inertial navigation system, so as to finish transfer alignment. By adopting the ship large azimuthmisalignment angle transfer alignment method, the rapid and high-precision alignment problem of a ship under a condition of a large azimuth misalignment angle and a large lever arm error is solved.

The invention aims at providing a single-axle table calibration method for a fiber optic gyro strapdown inertial navigation system. The fiber optic gyro strapdown inertial navigation system is placed on a single-axle table, the fiber optic gyro strapdown inertial navigation system is electrified for preheating, the angular velocity outputted by a fiber optic gyro and the specific force outputted by a quartz flexible accelerometer are collected, then the single-axle table is controlled to rotate at 90 degrees counter-clockwise around a rotating shaft three times, the angular velocity outputted by the fiber optic gyro and the specific force outputted by the quartz flexible accelerometer at each time are respectively collected, and the drift of the fiber optic gyro in an x, y and z-axis coordinate system of an inertia device and the zero bias value of the quartz flexible accelerometer in the x, y and z-axis coordinate system of the inertia device are further obtained. The method can measure the drift of the fiber optic gyro and the zero bias value of the quartz flexible accelerometer by utilizing the single-axle table to rotate into different angular positions; furthermore, the calibration cost of the single-axle table is low, the steps are simple, and the single-axle table only needs to be placed on the ground during the calibration without a laboratory.

The present invention relates to a z-axial solid-state gyroscope. Its main configuration is manufactured with a conductive material and includes two sets of a proof mass and two driver bodies suspended between two plates by an elastic beam assembly. Both surfaces of the driver bodies and the proof masses respectively include a number of grooves respectively perpendicular to a first axis and a second axis. The surfaces of the driver bodies and the proof masses and the corresponding stripe electrodes of the plates thereof are respectively formed a driving capacitors and a sensing capacitors. The driving capacitor drives the proof masses to vibrate in the opposite direction along the first axis. If a z-axial angular velocity input, a Coriolis force makes the two masses vibrate in the opposite direction along the second axis. If a second axial acceleration input, a specific force makes the two masses move in the same direction along the second axis. Both inertial forces make the sensing capacitances change. Two z-axial solid-state gyroscopes and two in-plane axial gyroscopes can be designed on a single chip to form a complete three-axis inertial measurement unit.

The invention provides a multi-list redundant strapdown inertial measuring device for a laser gyroscope. According to the multi-list redundant strapdown inertial measuring device, three orthogonally-arranged gyroscopes Gx, Gy and Gz and two obliquely-arranged gyroscopes Gs and Gt can be used for sensing an angle speed of a carrier moving in an inertial space; three orthogonally-arranged accelerometers Ax, Ay and Az and two obliquely-arranged accelerometers As and At can be used for sensing a specific force of the carrier moving in the inertial space; a resolving computer of the device can be used for collecting inertial information in real time and at a high speed and the inertial information is sent to a navigational computer in real time by a high-speed bus; after the navigational computer obtains inertia type instrument information transmitted by the strapdown inertial measuring device for the laser gyroscope, information including a course, a posture, a speed, a position and the like of the carrier can be calculated and output in real time and is supplied to a guidance and posture control system for use.

The invention relates to a gravity measuring method based on strapdown inertia/GPS combined auxiliary horizontal angular motion isolation; the method comprises the following steps: in an actual measurement process, a double-shaft stabilized platform is arranged outside the IMU of a gravimeter so as to isolate the horizontal angular motion of a carrier, and a horizontal torquing amount is formed bynavigation resolving under dynamic conditions so as to control the platform to track the geography level; in the anaphase processing process of the gravity measuring data, the DGPS information is combined so as to complete Kalman filter estimation of residual horizontal errors, thus rotating the IMU specific force measured value to the geography coordinate system direction through postures. In the actual measurement process, the method uses the double-shaft inertia stabilized platform to control, thus keeping the IMU the be basically at the geography horizontal position; in the anaphase processing process of the actual measurement IMU data, the high precision difference GPS information is combined to complete the Kalman filter estimation of residual horizontal errors, thus realizing estimation and compensation of the gravity sensor element errors, and improving the dynamic environment adaptability and gravity measuring precision in the gravity measurement.

A ground speed detecting method suitable for fiber top strap-down inertial navigation system relates to a rowing compensation process which solves the problem that the rowing effect brings influence to the ground speed detecting in a high dynamic environment or a high frequency bration environment. The invention respectively acquires the speed measuring increment and angle increment measured value of a carrier opposite to an inertial frame by a specific force signal and a palstance signal during the refresh cycle of the ground speed, and then acquires the speed rotating term; the speed increment of the carrier in the refresh cycle opposite to the inertial frame is calculated by the speed rotating term and the rowing compensation term and then the speed increment acquired is projected to a n frame of the inertial frame; the speed increment caused by the acceleration of gravity and the corriolis acceleration is calculated in the n frame of the inertial frame and finally the ground value is got by a basic equation calculation of the inertial navigation system. The invention is suitable for that the carrier is under a high frequency bration or high mobile situation.

Navigation units, systems, and methods for use in the context of personal navigation, and associated methods for initialization, navigation, assistance, and correction, all in the field of inertial navigation and related applications. The inertial navigation units, systems, and methods of the invention utilize multiple accelerometers to gather specific force data for improvement of the initialization, navigation, assistance, or corrective processes.

A method for guiding a ballistic missile to a target has a first mode guidance process that drives a magnitude of a velocity-to-go (Vgo) vector toward zero. On regular intervals, a proportional velocity deficit value is calculated as equal to a time constant (Tau) multiplied by a specific force magnitude (sf). When the magnitude of the Vgo vector has been driven to less than or equal to the proportional velocity deficit value by way of the first mode guidance process, a second mode guidance process is initiated. The second mode guidance process constrains the magnitude of the Vgo vector to be equal to the proportional velocity deficit value throughout the remaining portion of powered flight.

The invention relates to a wheel speed measuring method and a device based on a wheel load type intelligent sensor. The centripetal specific force acceleration of a wheel is measured by an MEMS acceleration sensor, and the centripetal acceleration of the operation of the wheel is obtained through signal filtration and gravity acceleration compensation so as to calculate the wheel speed. The device comprises a wheel load wheel rotating speed measuring module and a central control module in a vehicle, wherein the wheel load wheel rotating speed measuring module is arranged on the surface of the hub of the wheel, and comprises a micro inertial measuring unit, a micro controller, a wireless receiving and transmitting unit and a power module; the central control module in the vehicle comprises a wireless receiving and transmitting unit, a digital signal processor, a man-computer interactive unit and a power module; and the wheel load wheel rotating speed measuring module and the central control module in the vehicle are provided with two-way communication function.

The present invention discloses a structural and mechanical model and modeling methods for human bone based on bone's hierarchical structure and on its hierarchical mechanical behavior. The model allows for the assessment of bone deformations, computation of strains and stresses due to the specific forces acting on bone during function, and contemplates forces that do or do not cause viscous effects and forces that cause either elastic or plastic bone deformation.

The invention discloses a quadratic overload term test method for a flexible gyroscope based on optical fiber monitoring and a centrifuge with a two-axis turntable, which belongs to the technical field of inertia. The test method includes the steps: firstly, mounting an optical fiber gyroscope and the flexible gyroscope on the centrifuge with the two-axis turntable, electrifying the flexible gyroscope and the optical fiber gyroscope and acquiring static output data after preheating stabilization; secondly, synchronously rotating the centrifuge along with an outer turntable and an inner turntable of the two-axis follow-up turntable and acquiring overload output data after rotation speed stabilization; and finally, calculating secondary overload term coefficient. The test method has the advantages that the relationship between a quadratic term of a specific force-sensitive error and environmental overload acceleration in a static drift model of the flexible gyroscope can be calibrated, a quadratic polynomial model of specific force-sensitive error terms can be established, and a test scheme is provided for calculating and determining the influence of nonlinear errors of the flexible gyroscope on system errors.