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154 results about "Nutation" patented technology

Nutation (from Latin nūtātiō, "nodding, swaying") is a rocking, swaying, or nodding motion in the axis of rotation of a largely axially symmetric object, such as a gyroscope, planet, or bullet in flight, or as an intended behaviour of a mechanism. In an appropriate reference frame it can be defined as a change in the second Euler angle. If it is not caused by forces external to the body, it is called free nutation or Euler nutation. A pure nutation is a movement of a rotational axis such that the first Euler angle is constant. In spacecraft dynamics, precession (a change in the first Euler angle) is sometimes referred to as nutation.

Attitude control system for space vehicle and method thereof

The invention discloses an attitude control system for space vehicle and a method thereof. The control system has only one biased momentum wheel, one set of tri-axial magnetic torquer and one attitude controller loaded with algorithm. The method comprises a step of rate damping controlling, a step of initially capturing controlling and a step of stationarity controlling. At the rate damping stage, geomagnetism change is used to control the magnetic control of three passages of a satellite by B-dot; at the initially capturing stage, the magnetic control is realized, PD control is performed by pitching and the passages are rolled and yawed to carry out nutation and precession composite control; at the stationarity controlling stage, the magnetic control is realized, PD control is performed by pitching and the passages are rolled and yawed to carry out nutation and precession composite control. The capturing stage and the stationarity controlling stage fully depend on magnetic torquer to perform positive magnetic control, thereby changing which a satellite only uses a magnetic torquer to carry out unload of the momentum wheel or auxiliary magnetic control, so as to refine system configuration to further improve reliability of the system. Momentum of a satellite is biased to rotate on the ground, so as to ensure stable separation of the satellite without performing air injection control. Therefore, the magnetic torquer can be used for realizing fast and stable initial rate damping.
Owner:SHANGHAI ENG CENT FOR MICROSATELLITES

Space tumbling target de-spinning control method based on permanent magnet eddy current effect

ActiveCN106406329AMeet the attitude adjustment control requirementsIncrease the working distanceCosmonautic vehiclesCosmonautic partsNutationEngineering
Disclosed is a space tumbling target de-spinning control method based on a permanent magnet eddy current effect. The method comprises the following steps: a service spacecraft docks in the working space of a mechanical arm, and is kept at a safety distance from a tumbling non-cooperative target; a visual inspection system carried by the service spacecraft measures the direction of a target angular momentum vector H and the direction of a spin axis position vector Zb, and the mechanical arm drives a permanent magnet eddy current braking device at the end to an initial de-spinning position, and the docking position is 100mm from the surface of the target in the direction of the target angular momentum vector; the permanent magnet eddy current braking device is started, the direction of a vector outputting an external torque T1 is corrected according to the real-time change of attitude angle in the tumbling process of the target until the angle of nutation attenuates completely, and the rotation state of the target is changed to a single spinning motion state; the position of the permanent magnet eddy current braking device is adjusted to the side of the tumbling non-cooperative target, the permanent magnet eddy current braking device is started to output a brake torque T2 until the single spinning motion state attenuates completely; after the target is completely de-spun, an end actuator is replaced with a grasping paw, and the target is captured directly by the mechanical arm.
Owner:黑龙江省工研院资产经营管理有限公司

Micro-motion target scattering point track association method based on distance-instant Doppler image

ActiveCN105259553AOvercome the shortcomings of poor correlation effectTrack correlation error is smallRadio wave reradiation/reflectionNutationHigh resolution imaging
The invention discloses a micro-motion target scattering point track association method based on a distance-instant Doppler image. The method comprises the following steps of (1) receiving an inverse synthetic aperture radar echo; (2) carrying out inverse synthetic aperture radar echo pretreatment; (3) through the distance-instant Doppler image, acquiring a two-dimension coordinate of a micro-motion target scattering point; (4) carrying out two-dimension track association; (5) using a rooting multiple signal classification Root-MUSIC method to correct a track matrix; (6) acquiring a track association result of the micro-motion target scattering point. A domain associated to the scattering point is converted into a slow time-distance-instant Doppler domain with a high separability from a distance-slow time domain; separability of the micro-motion target scattering point is enhanced; for complex motion forms of spinning, processional motion, nutation and the like, advantages that universality is possessed, track association precision is high, an association error is small and so on are achieved; forceful guarantee can be provided for subsequent high-resolution imaging and target feature extraction.
Owner:XIDIAN UNIV

Racemization control method for under-actuated satellite

The invention discloses a racemization control method for an under-actuated satellite. The method comprises the following steps of: (1) determining an initial self-rotating shaft position of the under-actuated satellite by the adoption of an attitude sensor, and determining a direction and an amount of racemization control according to a position of a target self-rotating shaft; (2) determining geometric relationship between an injection control moment and a racemization control direction produced by each injection control engine, and selecting the injection control engine with the largest amount of the injection control moment in the racemization control direction as a racemization control engine; and (3) in a preliminary stage of racemization, adopting an integer multiple self-rotating period fully spraying method, in a final phase of racemization, adopting a symmetrical point spraying method, using the racemization control engine to carry out racemization control, after primary racemization is finished, enabling a planet to be naturally damped for a period of time, and then carrying out the next racemization control until a self-rotating shaft of a satellite reaches a target self-rotating shaft. According to the method, the operation of a racemization control strategy is simple and convenient, and nutation produced by racemization control can be reduced at the same time.
Owner:BEIJING INST OF CONTROL ENG

Method for designing trap parameter of magnetic suspension flat high speed rotor system

InactiveCN101247097AGuaranteed stabilityDecrease the design value of pole dampingMagnetic holding devicesNutationSelf excited
The present invention provides a method for designing the parameter of the wave trap of the magnetic suspension flat high-speed rotor system. The magnetic suspension flat high-speed rotor system is considered with a kinetics model of the first order elastic mode and is translated into a complex-coefficient single-variate open-loop transfer function. The double-frequency Bode chart of the open-loop transfer function of the complex coefficient in different rotary speed is drawn. The phase angle allowance of elastic mode in each rotary speed is calculated, and the series-connected progression, central frequency and polar point amortization of the elastic self-excited vibration restraining used wave trap are designed according to the phase angle allowance curve. Basing on the double-frequency Bode chart the invention presents a method for designing the parameter of the wave trap which comprises a magnetic suspension flat high-speed rotor system with strong gyroscopic effect and is used for restraining the first order elastic self-excited vibration. Compared with the common multiple-variate system designing method such as state space analyzing method and the like, not only has excellent immediacy and robustness, but also can minimize the effect of the wave trap to the nutation stability, and thus the invention the invention is more suitable to be used in the actual magnetic suspension high-speed rotor system such as posture-controlling energy-accumulating fly wheel, the magnetic suspension counteracting wheel, the magnetic suspension control moment gyroscope and the like.
Owner:BEIHANG UNIV

Projectile nutation angle extraction method based on radar Doppler data

The invention relates to a projectile nutation angle extraction method based on radar Doppler data. The method is characterized by comprising the following specific steps of arranging a radar tail chasing distributed station at the side rear part of an artillery or a rocket artillery, carrying out tracking measurement on a flying artillery shell or a rocket artillery shell, and estimating the radial velocity of a centroid; calculating micro motion speeds; extracting a precession period; resolving a velocity vector; calculating the nutation angle of a projectile. According to the method, the difficult problem in nutation angle measurement of the flying projectile under the conditions of long distance is solved effectively, and the motion of the rotating projectile in the air includes micro motions relative to the centroid, such as precession and nutation, besides centroid motion; radar signals are subjected to periodic modulation, namely micro-Doppler effect, by the micro motions. Internal data of the radial velocity obtained through radar measurement contain information on the micro motions, such as nutation, a nutation angle curve of the projectile can be obtained through processing the internal data, and the nutation angle of the projectile is obtained through an established micro-motion velocity equation.
Owner:冷雪冰

Electromechanical integration nutation oscillating tooth transmission device

InactiveCN102594016ARealize constant speed ratio driveEasy to processMechanical energy handlingNutationEngineering
The invention relates to an electromechanical integration nutation oscillating tooth transmission device, which is characterized in that the nutation oscillating tooth transmission device composed of a fixing disc end cover, a first end cover bearing, a fixing disc, a rotating drum, a nutatoin disc, a rotating disc end cover, a second end cover bearing, a rotating disc, an outer end cover and an output shaft is installed in a box body. A bearing and the rotating drum are arranged on the outer lateral face of the nutation disc, and a motor composed of a rotor, a permanent magnet and a stator is installed along the outer lateral face of the rotating drum to achieve engagement of a roller of the nutation disc and teeth of the fixing disc, engagement of the roller of the nutation disc and teeth of the rotating disc and achieve the fact that a bolt and an output shaft fixedly connected with the rotating disc output torque. The electromechanical integration nutation oscillating tooth transmission device is novel and unique in design and compact in structure, has the advantages of no contact, small vibration and overload protection due to utilization of magnetic force transmission, avoids the fact that an inclined shaft section in the nutation oscillating tooth transmission device is difficult to machine, is capable of remarkably prolonging service life of a rotating arm bearing due to the fact that the rotating arm bearing is placed outside the nutation disc and has the advantages of being fewer in part number, high in bearing capability, low in noise, high in efficiency and thelike.
Owner:DALIAN JIAOTONG UNIVERSITY

Optimal selection method of navigational stars of star map simulator based on star density

The invention discloses an optimal selection method of navigational stars of a star map simulator based on star density. The optimal selection method comprises the following steps: firstly, processing a star catalogue, extracting effective data fields, carrying out related data processing to obtain six pieces of data corresponding to each fixed star, and then performing proper motion, precession and nutation correction on extracted right ascension and declination values respectively; secondly, according to given optical axis orientation and the size of a field range, extracting fixed stars in the field range and establishing an observational star database; thirdly, on the basis of the observational star database, performing image surface partition and star density calculation respectively by use of an ITSI (Information Technology System Infrastructure) optimal selection method of the navigational stars, and satisfying a set navigational star threshold, and finally realizing the optimal selection of the navigational stars and establishing a navigational star database. The method is relatively simple, but the navigational star database obtained by use of the method is relatively low in standard deviation and relatively even in distribution, and both efficiency and effect are achieved; the established navigational star database is reasonable and significant for smooth implementation of star map matching.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS

Gain scheduling control method for magnetic suspension molecular pump

The invention discloses a gain scheduling control method for a magnetic suspension molecular pump. The method comprises the following steps of: calling a high-rigidity and high-damping control parameter to control the magnetic suspension molecular pump by using a dispersion PID (Proportion Integration Differentiation) controller when a rotor rotates at a low rotating speed, and gradually starting a displacement cross feedback controller when the speed of the rotor rises to a medium-low speed to effectively suppress rotor precession in the rotating process of the rotor and vibration caused by the structural mode of a system; when the rotating speed of the rotor reaches a medium speed, gradually switching the parameter of the dispersion PID controller to a low-rigidity and low-damping control parameter; and when the rotating speed of the rotor reaches a medium-high speed, gradually starting a speed cross feedback controller to suppress rotor nutation in the rotating process of the rotor and ensure that the rotor can stably reach a rated working rotating speed. Due to the adoption of the method, the technical problem of vibration caused by the rotor gyroscopic action in the working process of the molecular pump and the structural mode of the system is solved, the rotor vibration can be effectively suppressed in the working process of the molecular pump, and stable running of the magnetic suspension molecular pump can be ensured.
Owner:KYKY TECH +1

Variable-speed tilt momentum wheel precession control method based on variable-parameter nutation damping

ActiveCN107992063AInhibition of nutation instabilityImprove stabilityCosmonautic vehiclesCosmonautic partsNutationMomentum
The invention provides a variable-speed tilt momentum wheel precession control method based on variable-parameter nutation damping and relates to the field of motion control of a variable-speed tilt momentum wheel in order to solve the problem of reduction of stability and control precision of the variable-speed tilt momentum wheel due to rotor gyroscopic effect and two-dimensional tilt motion coupling. According to the method, frequency characteristics of direct-axis and quadrature-axis controlled members of the variable-speed tilt momentum wheel at a certain determined rotating speed are identified respectively through a tilt loop open-loop experiment; a relation between system nutation frequency and the rotating speed is determined according to the tilt loop open-loop experiment, and nutation instability of a nutation damper suppression system is designed. The frequency characteristics of the direct-axis and quadrature-axis controlled members of the variable-speed tilt momentum wheel are identified respectively through the tilt loop open-loop experiment, the nutation frequency is determined according to the quadrature-axis frequency characteristics at different rotating speeds,a variable-parameter nutation damper is designed accordingly, the nutation instability of the variable-speed tilt momentum wheel is suppressed, and a control structure of the system is provided on thebasis of the principle of precession control. Stability and control precision of the variable-speed tilt momentum wheel are improved.
Owner:HARBIN INST OF TECH

Full-automatic triaxial air bearing table micro-interference force moment measurement system and method

The invention discloses a full-automatic triaxial air bearing table micro-interference force moment measurement system and a method. The full-automatic triaxial air bearing table micro-interference force moment measurement system comprises an air floating ball and a ball socket, wherein a gyroscope is arranged on the air floating ball for measuring angular velocities omega m in three directions, three balancing mass blocks m1, m2 and m3 and a jet system are arranged on the air floating ball, the rotational inertia matrix of a system formed by the air floating ball, the gyroscope, the mass blocks and the jet system under coordinates of air floating ball is a 3*3 matrix Ia, the air floating ball can generate initial angular velocity by the jet system, the angular velocity omega m of the air floating ball during rotation can be measured by the gyroscope, and the interference force moments in three directions can be calculated according to Ia. According to the full-automatic triaxial air bearing table micro-interference force moment measurement system and the method, the interference problem between a bearing of the air floating ball and the ball socket can be effectively solved through nutation formed by a symmetrical structure during rotation entirely, and the interference force moment of the bearing of the air floating ball can be measured in a small-angle range.
Owner:SHANGHAI INST OF SATELLITE EQUIP

Rotating shaft torque measuring device based on surface transverse wave

The invention provides a rotating shaft torque measuring device based on a surface transverse wave. The rotating shaft torque measuring device comprises a measuring mechanism and a control mechanism which are matched with each other. The measuring mechanism comprises a rotating shaft body, a first surface transverse wave resonator arranged on the rotating shaft body through a binder and a second surface transverse wave resonator arranged on the rotating shaft body through the binder. The tangential Euler angles of the first surface transverse wave resonator and the second surface transverse wave resonator are characterized in that rotation angles are 0 degree, nutation angles are 38.8 degrees, and precession angles are 90 degrees. The rotating shaft torque measuring device has the advantages that: 1) a frequently-used rayleigh wave mode is no longer simply used for surface acoustic wave mode selection, and a surface transverse wave mode relatively low in propagation loss is adopted, so that the Q values of the resonators are larger, the demodulation accuracy of echo signals is improved, and the torque measuring precision is improved; and 2) the two STW resonators identical in structure are adopted, and the resonators are orthogonally arranged on the surface of the rotating shaft and form +/- 45-degree angles with the axial direction of the rotating shaft, so that the two resonators are arranged in the identical work environment.
Owner:SHANGHAI JIAO TONG UNIV
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