160 results about "True north" patented technology

The invention relates to an attitude testing apparatus and method based on an autocollimator. The apparatus mainly comprises the autocollimator, an optical hexahedron, a double-shaft electronic level meter and a pedestal with a leveling function. The method comprises the following steps: putting the attitude testing apparatus on a firm base, allowing the autocollimator to collimate a reflecting surface of an object, then collimating the optical hexahedron with an autocollimation gyro theodolite and measuring the included angle between the apparatus and a true north azimuth reference; starting the autocollimator for recording and retrieving of continuous data of the attitude of the reflecting surface of the object and starting the double-shaft electronic level meter for recording and retrieving of continuous data of horizontal attitude; and after completion of recording and retrieving of the data, processing the data of the autocollimator and the double-shaft electronic level meter by using a data processing method for the attitude testing apparatus so as to eventually obtain continuous changes of the attitude of the reflecting surface of the object in a geographic coordinate system, thereby meeting demands of continuous absolute measurement.

The invention discloses a satellite orientation based azimuth calibration method and device. According to the method, true north azimuths of two satellite antenna represented base lines are calibrated according to a high-precision relative positioning principle based on carrier phase ambiguity-resolving; the azimuths of the base lines are derived with angle measuring instruments such as a theodolite or a total station; the true north information of each azimuth to be measured is measured. According to the satellite orientation based azimuth calibration method and device, high-precision satellite orientation is used as an azimuth reference, and the theodolite is used to derive the true north azimuth of the azimuth reference for azimuth calibration. The satellite orientation based azimuth calibration method and device has the advantages that the ways of using traditional fixing marker post and the like are replaced by the use of a movably erectable GNSS (global navigation satellite system) antenna, no satellite differential station is required, azimuth calibration flexibility is greatly improved, and the azimuth calibration range is greatly widened.

Disclosed is a technique to estimate at least a portion of an attitude, such as an azimuth angle from true North, based on beam angles from a controlled reception pattern antenna (CRPA) to space vehicle locations. Other attitude information such as roll and/or pitch can also be estimated. The at least portion of the attitude can be provided with or without an additional sensor, such as a compass or magnetometer, an inertial measurement unit (IMU), or the like. An attitude estimate can be useful because oftentimes the attitude of an object can vary from its track or velocity direction.

A mobile device is described. The mobile device includes an electronic compass that generates compass data corresponding to an orientation of the mobile device relative to true north. A global positioning system (GPS) module receives a GPS signal from multiple satellites. The GPS module determines a heading direction of a vehicle transporting the mobile device relative to true north based on the position data when the vehicle is moving above a threshold velocity. A motion sensor generates motion data corresponding to a motion of the mobile device when the mobile device is moved. A processor adjusts the heading direction of the vehicle relative to true north based on the compass data when the vehicle is moving below the threshold velocity.

The invention provides a ground testing method of a star sensor. The method comprises the following steps of: adjusting the star sensor by using a theodolite so that the Z axis of the star sensor points to true north and the Y axis of the star sensor vertically faces towards zenith; receiving a quaternion of the star sensor under an inertial coordinate system; converting the posture of the star sensor into a quaternion under a WGS84 coordinate system; converting the quaternion under the WGS84 coordinate system of the star sensor into a three-axis Euler angle; continuously operating the star sensor for 30 minutes, storing the difference between a roll angle and the local longitude and the difference between a drift angle and the local latitude in real time, and counting precisions of the roll angle and the drift angle; and storing the difference between a pitch angle and the local longitude in real time, and counting the precision of the pitch angle. According to the method disclosed by the invention, the testing process is simple; any special equipment is unnecessary; the method is not only used for testing the precision of the three-axis Euler angle of the star sensor but also used for completely testing the three-axis polarity of the star sensor; and in addition, only when the time precision satisfies requirements, the method is also used for testing the absolute longitude of the star sensor.

The invention relates to a crosswind information estimation method based on the unmanned aerial vehicle crabbing method. The crosswind information estimation method based on the unmanned aerial vehicle crabbing method comprises the following steps that test data generated during unmanned aerial vehicle crabbing are obtained; the obtained test data are processed; crosswind information estimation is conducted according to the relation between the yaw angle phi and the track angle phi <s> and the relation between the airspeed Va and the ground speed Vd, wherein crosswind information includes the amplitude of crosswind and the crosswind azimuth angle relative to the geomagnetic true north, and a certain included angle exists between the pointing direction of the head of an unmanned aerial vehicle and the crosswind. According to the crosswind information estimation method based on the unmanned aerial vehicle crabbing method, the requirement for real-time crosswind estimation in an unmanned aerial vehicle flight test can be met, the crosswind applied to the unmanned aerial vehicle when the unmanned aerial vehicle flies flat can be measured quite accurately by analyzing the speed relation existing when the unmanned aerial vehicle crabs, the safety coefficient is increased when the unmanned aerial vehicle flies, and the completeness of information is guaranteed.

The invention provides a method for constructing a geographic coordinate system with a laser tracker. A level of the laser tracker is aligned with the geoid, so that the horizontal of the place where the tracker is located is found, a high-precision theodolite is then utilized to find the direction of the true north, the adjusted theodolite is used for measuring the horizontal angles between fourtarget balls placed according to certain requirement, the tracker measures and projects the four target balls into a horizontal plane, so that the mutual positional relation among the four points in the horizontal plane is obtained, and by means of calculation, the horizontal included angle between the connecting line of the projected points of the corresponding target balls and the direction of the true north can be obtained. Finally, tracker software is used for establishing a coordinate system (the origin is given according to the requirement) with the direction of the connecting line of the projected points of the corresponding target balls and the direction of the normal vector of the horizontal plane as axes and rotating the coordinate system around the direction of the normal vector of the horizontal plane for the horizontal included angle, and thereby the needed geographic coordinate system is obtained. The method enables laser tracker to have the function of establishing the geographic coordinate system, and can also be applied to other cases needing the establishment of geographic coordinate systems.

The invention relates to an indoor positioning method for a smartphone user based on terrestrial magnetism-corrected inertial navigation. The method comprises the following steps: dividing a to-be-positioned area into small grids according to a plane map of a building; allowing the smartphone user to acquire the intensity data of terrestrial magnetism at the center of each grid for a period of time by using a smartphone with a built-in magnetometer; averaging the intensity data of terrestrial magnetism acquired in each grid and constructing and storing an off-line terrestrial magnetism fingerprint database; allowing the user to start to walk with the smartphone, detecting steps and estimating step length by processing the data of an accelerometer of the smartphone, and acquiring an included angle between a movement direction and a true north direction and current intensity of terrestrial magnetism by processing the data of a gyroscope; acquiring a predicted value of a current state; calculating a covariance matrix and Kalman gain in a prediction phase; calculating observation and measurement results; and updating a state. The method provided by the invention can realize high indoor positioning precision only by using the smartphone.

The most accurate method of finding the true north is through astronomical observations, for example, by observing the position of the sun. However, the procedure is complicated. The instantaneous position of the sun must be calculated from astronomical data for each instance of observation, and the operator must wait for the predetermined time to come. Elaborate manual adjustments are required. The present invention discloses an automatic solar compass comprising a cylindrical omni-directional lens, a detection means, and a servomechanism. It is as easy to use as the magnetic compass, but much more accurate and reliable than the magnetic compass.

An imaging system includes a processor, a detection assembly configured to collect survey data characterizing a respective height and location of physical features of a geographic region, a receiver assembly configured to provide location data characterizing a geolocation of the geographic region, a tilt sensor configured to provide tilt data characterizing an inclination of the detection assembly with respect to gravity, and a magnetic-field sensor configured to provide field data characterizing a magnetic field associated with the geographic region. The processor is configured to perform processing of the survey data and tilt data to yield a first corrected data set, obtain magnetic-deviation data associated with the geographic region, determine an indication of true north, and process the first corrected data set and true-north indication to yield a second corrected data set comprising the first corrected data set oriented to true north.

The invention relates to a wind cup type fiber Bragg grating wind speed and direction sensor, which belongs to the technical field of photoelectron measurement. Three wind cups are arranged in a way of forming included angles of 120 degrees together with one another; the central axis of a 1# wind cup is vertical to a true north direction; grooves are formed in the lateral edges of the three wind cups to the centers of the wind cups, and are connected with the free ends of three equal-strength cantilever beams respectively in the centers of the wind cups; the three equal-strength cantilever beams are fixedly arranged on the upper half part of a boss in a helical rising way; every two gratings are symmetrically stuck to the central axes of the front face and the back face of each equal-strength cantilever beam respectively after being coupled; six fiber Bragg gratings are coupled in a boss base through input and output fibers; and the input and output fibers are connected to a fiber grating signal demodulator. A fiber grating information material has the special physical properties of small size, electromagnetic interference resistance, long service life and the like, so that real-time online monitoring of the wind speed and wind direction of a wind load alarm control unit is realized, and high interference resistance and high accuracy are realized.

The invention discloses a place cell bionic robot navigation algorithm which comprises the steps of: A1, firstly, capturing a panoramic photo by a robot wide angle camera, converting the panoramic photo into a gradient image, then filtering the gradient image by using a Gaussian difference filter, detecting characteristic points, carrying out log polar transformation on a local region near the characteristic points, wherein the characteristic points correspond to special road signs; A2, obtaining angle of each road sign relative to the true north direction as an azimuth angle, wherein the true north direction is provided by a compass and the azimuth angles and the road signs jointly determine a position cell of the current time; A3, jointly determining a transfer matrix by the position cell of the current time and a position cell of the former time, when a robot explores in an unknown environment, continuously forming transfer matrixes, forming a cognitive map by the transfer matrixes; and A4, jointly determining a movement transformation matrix by the transfer matrixes and the cognitive map, wherein the movement transformation matrix is in charge of sending a movement command. The invention can be applied to an intelligent ground-cleaning robot, a battlefield searching and rescuing robot, and the like.

The invention relates to a gyro compass multifunction automatic orientation north-searching device, the technical proposal is that: when a rotary table is arranged in an orientation position, a controller calculates the error between a predetermined rotary table orientation position and the output angle value of an encoder; correct controlling quantity is thus calculated according to the error value and width-adjusting wave is output to drive a motor to lead the rotary table to rotate to next orientation position; the device which detects an included angle between the encoder null position and the true north receives, on a plurality of orientation positions in a scope of one cycle, the data of northbound component of a gyro and the angle value which is output by the encoder, fits the curve relationship between the north component and the corresponding dislocation of the encoder angle value, and calculates precisely the angle between the null position of the encoder and the true north. The invention has a short north-searching time and high precision of north-searching.

The invention relates to an automatic latitude measuring and calculating and automatic precision compensating method of a pendulum gyro north seeker. The method is characterized in that the geographic latitude is resolved by utilizing the pendulum period measured by an alidade of the pendulum gyro north seeker under a non-tracking state, and the directive coefficient is calculated, so that the precision compensation of deviation brought about by torsion zero deviating from true north is completed, and the method comprises the four steps of calibrating the relationship coefficient of the period and the latitude, starting a north seeking process, measuring the period under the non-tracking state, resolving the latitude by the non-tracking period, and correcting the torsion zero deviation automatically. Compared with the prior art, the automatic latitude measuring and calculating and automatic precision compensating method of the pendulum gyro north seeker has the advantages that in actual applications, the latitude is not required to be input before measurement, and the directive coefficient is also not required to be calibrated and calculated; through the constant coefficient relationship of the period and the latitude, which is calculated in advance in a calibrating site, the latitude at the site can be resolved only by measuring the non-tracking pendulum period of a measured site, and further a measurement result is corrected. The method can be widely applied to the fields of aviation, aerospace, geodetic measurement, guided missile aiming and the like.