88 results about "Angular momentum" patented technology

The invention discloses an EAM data set polar shift forecasting method based on noise suppression, and belongs to the technical field of earth science, and the method comprises the steps: obtaining polar shift observation data in an IERS C04 data set, and obtaining geodetic measurement angular momentum data through the conversion of a Arweel equation; obtaining an effective angular momentum data set, and performing noise reduction processing on effective angular momentum observation data in the effective angular momentum data set by using the geodetic measurement angular momentum data to obtain effective angular momentum observation data after noise reduction processing; splicing the effective angular momentum observation data and the effective angular momentum forecast data, performing least square fitting on the obtained spliced effective angular momentum data, and further combining with a Kalman filtering algorithm for noise reduction to obtain effective angular momentum forecast data after noise reduction processing; and based on the effective angular momentum observation data after the noise reduction processing and the effective angular momentum forecast data after the noise reduction processing, carrying out polar shift forecast. According to the method, the polar shift forecasting precision is effectively improved.

Aspects of the disclosure relate to reporting and correcting a spatial misalignment of an orbital angular momentum (OAM) waveform communicated from a second device to a first device. In an aspect, the first device receives from the second device, the OAM waveform having a spatial misalignment with respect to the second device. The first device determines the spatial misalignment and further determines spatial coordinates for correcting the spatial misalignment and / or one or more channel measurements of the OAM waveform. Thereafter, the first device sends a report based on the spatial misalignment to the second device, the report including the spatial coordinates for correcting the spatial misalignment and / or the one or more channel measurements. The first device then receives an adjusted OAM waveform from the second device, wherein the adjusted OAM waveform is received having a corrected spatial alignment with respect to the second device based on the report.

The invention discloses an anti-interference flight control method for a multi-rotor unmanned aerial vehicle. The method comprises the following steps: establishing an attitude dynamic model of the multi-rotor unmanned aerial vehicle; according to a moment of momentum theorem and an Euler equation, establishing an unmanned aerial vehicle attitude kinetic equation; setting a control moment in the man-machine attitude kinetic equation as a dependent variable, and performing first-order Taylor expansion at any point; adding expectation into the expanded kinetic equation to obtain an improved incremental nonlinear dynamic inverse controller; using real-time measured values of motion variables of the multi-rotor unmanned aerial vehicle in the improved incremental nonlinear dynamic inverse controller, and optimizing the improved incremental nonlinear dynamic inverse controller by adopting a control closed-loop transfer function of an attitude angular acceleration loop and a disturbance closed-loop transfer function of the attitude angular acceleration loop; and controlling the attitude of the multi-rotor unmanned aerial vehicle by using the optimized improved incremental nonlinear dynamic inverse controller. According to the method, the dependence of the unmanned aerial vehicle control method on the model can be reduced, and the stability of the multi-rotor unmanned aerial vehicle is improved.

An optical device comprises a metasurface including a plurality of nanostructures. The nanostructures convert an input light of an arbitrary spin state into an output light of an arbitrary total angular momentum state characterized by a superposition of two independent orbital angular momentum (OAM) states.

The invention provides a complex connection multi-body dynamics modeling method for a large-inertia rotating load, relates to the technical field of spacecraft dynamics modeling, is applied to a satellite of which a satellite platform and a load platform are both large-inertia rigid bodies, and comprises the following steps: establishing a reference coordinate system of the satellite; acquiring position vectors and angular velocity vectors of the satellite platform and the load platform according to the reference coordinate system; and according to the position vector, the angular velocity vector, the mass of the satellite platform and the mass of the load platform, establishing an angular momentum moment equation of the satellite relative to the center of mass of the satellite, a momentum moment equation of the load platform relative to the connection point, a center-of-mass translation equation of the satellite and a center-of-mass translation equation of the load platform. According to the scheme, the dynamic modeling of the complex connection multi-body satellite with the large-inertia rotating load is realized.

The present application relates to the technical field of geophysics, and particularly relates to a method for predicting earth rotation parameters based on least squares and long short-term memory network, comprising: collecting and preprocessing basic sequence data of earth rotation and effective angular momentum data; converting the preprocessed basic sequence data of earth rotation into geodetic angular momentum; fitting the effective angular momentum data and the geodetic angular momentum to obtain fitted sequences and residual sequences of the effective angular momentum and the geodetic angular momentum respectively; inputting the residual sequences of the effective angular momentum and the geodetic angular momentum into a long short-term memory network model to obtain error terms of the effective angular momentum and the geodetic angular momentum; and integrating the fitted sequences of the effective angular momentum and the fitted sequences, the error terms of the effective angular momentum and the geodetic angular momentum to obtain a prediction result of the earth rotation parameters. Thus, the problems that the traditional earth rotation parameter prediction method is difficult to capture the complex nonlinear characteristics in the change of the rotation parameters are solved.

The invention discloses an autonomous underwater vehicle attitude regulation and control method and system, and relates to the technical field of underwater vehicle control, and the method comprises the following steps: collecting the current attitude parameter of an underwater vehicle in real time, and obtaining a deviation error signal of the current attitude parameter and an expected attitude parameter; acquiring a control signal for controlling the flywheel rotating speed or the flywheel angular acceleration based on the deviation error signal; the control signal is input to a driver used for controlling the flywheel to rotate, the flywheel is driven to rotate according to the expected flywheel rotating speed or flywheel angular acceleration, the flywheel generates corresponding angular momentum, and driving torque is generated based on the angular momentum; the driving torque is applied to the vehicle body in an equal-size and reverse mode, and the posture of the underwater vehicle is regulated and controlled. According to the method, the attitude of the underwater vehicle is regulated and controlled by utilizing the internal torque characteristic of the flywheel, the flywheel can realize one-axis one-control, control algorithm decoupling is realized, a distribution algorithm does not need to be introduced, the design is simple, and the control process is clear.

The invention discloses a multi-purpose water robot. The multi-purpose water robot comprises a shell, a steering mechanism, a propelling mechanism and a control system, the steering mechanism comprises a rotating disc arranged in the shell in the transverse direction and a steering driving device fixed in the shell, the rotating disc can be driven by the steering driving device to rotate around the central axis of the rotating disc, and the shell floats on the water surface. When the rotating disc rotates, reaction torque applied to the shell can drive the shell to rotate in the direction opposite to the rotating direction of the rotating disc, and steering is achieved. By arranging the rotating disc driven by the steering driving device in the machine body and utilizing the angular momentum conservation principle, when the rotating disc rotates at a high speed around the central axis of the rotating disc, the shell can rotate at a high speed in the opposite direction under the driving of reaction torque, steering is achieved, and dependence on lateral thrust or differential steering of a traditional propeller is not needed; and the turning radius is small, and the problem that a traditional water surface robot is difficult to flexibly avoid obstacles due to the too large turning radius is effectively solved.

Aspects of the present disclosure relate to a formula-based inter-circle precoding weight determination for an orbital angular momentum (OAM) communication system. Some aspects of the present disclosure relate to an apparatus and method for wireless communication, the apparatus including a processor, an antenna element including a first subset and a second subset of the antenna elements, and a memory coupled to the processor, the memory storing instructions that, when executed by the processor, cause the processor to transmit a first reference signal using a first OAM mode via the first subset of the antenna elements, transmit a second reference signal using the first OAM mode via the second subset of the antenna elements, and receive information indicating a subset of antenna elements of the plurality of antenna elements to use to transmit the first OAM mode. Other aspects, embodiments, and features are also claimed and described.

The invention discloses a spatial multi-body system dynamics modeling method based on a Lagrangian multiplier method. The method comprises the following steps: firstly, establishing a coordinate transformation matrix from a local coordinate system to a global coordinate system of each component in a space; defining the pose of the movable component according to the center-of-mass coordinate and the Euler angle, and determining a generalized coordinate; a position constraint equation is established for the kinematic pair, and numerical expressions of speed and acceleration constraint equations are obtained after primary and secondary derivation; the velocity constraint equation is converted through the spatial angular velocity matrix, the vector cross-multiplication property and the vector cross-multiplication symmetry, and a Jacobian matrix and a numerical expression of a time partial derivative term are obtained; based on the corrected Lagrange multiplier method, considering a cross multiplication term of angular velocity and angular momentum of rotation of the space component, establishing a kinetic equation and solving the kinetic equation; and establishing an association rule of the Euler angle and the space angular velocity to realize conversion between the two. Therefore, the method provided by the invention is suitable for various spatial multi-body systems, solves the difficulty of the existing modeling method in processing complex constraints, and fills up the defects in the prior art.

A satellite control system fault detection method based on cooperative monitoring of energy and angular momentum comprises the following steps: firstly, setting a detection statistical period value, calculating a satellite average energy value, a theoretical angular momentum change value and a measurement angular momentum change value of each statistical period, then comparing the satellite average energy value, the theoretical angular momentum change value and the measurement angular momentum change value with a satellite average energy value of a previous statistical period, and scoring; comparing and grading the consistency of the theoretical angular momentum change value and the measured angular momentum change value, comprehensively judging the grading value, giving a satellite attitude control abnormity mark, and when the satellite attitude control abnormity is confirmed, performing subsequent processing to enable the satellite to autonomously switch into an attitude control safety capture mode.

The application discloses a dimension reduction method for river hydrodynamic simulation, and specifically comprises the following steps: data collection; constructing a two-dimensional plane hydrodynamic model based on shallow water equation; adding the influence of curvature-induced secondary flow into the shallow water equation through a dispersion stress term; further introducing the contribution of the density gradient to the angular momentum into the angular momentum conservation equation; coupling the convection-diffusion equation of the dispersion stress to construct a two-dimensional plane hydrodynamic-matter transport finite element model; and calculating the average flow field of water depth and the secondary flow intensity. The three-dimensional effect of the secondary flow driven by the streamline bending and the density difference is added into the two-dimensional equation through the dispersion stress term, and the shallow water equation and the transport equation are coupled and solved, so that the simulation precision of the two-dimensional model is greatly improved, and fast and high-precision simulation of long-term evolution of the large river system topography is realized.

The present invention provides a satellite jet angular momentum unloading method and system, wherein the method includes: calculating the angular momentum that needs to be unloaded by the reaction wheel group in the directions of the three orthogonal coordinate axes of the satellite; determining the on-threshold and off-threshold of jet unloading; determining the unloading requirement of the three-axis unloading angular momentum based on the on-threshold and off-threshold; correcting the unloading state of each axis based on the unloading requirement of the three-axis unloading angular momentum; wherein, if the three-axis angular momentum unloading requirement is to unload the angular momentum of three axes or one axis, the unloading state correction is not performed; if the angular momentum of two axes needs to be unloaded, the unloading state is corrected to unload the larger angular momentum of the two axes; and obtaining the unloading jet width instruction based on the corrected unloading state of each axis. The present invention can improve the efficiency of jet unloading angular momentum and reduce fuel consumption; it can keep the three-axis angular momentum within a smaller range for a longer time, and reduce the residual angular momentum of the reaction wheel after the jet unloading mode is switched out of the on-orbit remote control.

A method for controlling a set of gyroscopic actuators of a satellite, distributed into two coplanar subsets, is described, the method comprising: Receiving a setpoint angular momentum, Determining an angular momentum to be provided by each coplanar subset (, ), from a distribution parameter, between the two subsets, of a component of the setpoint angular momentum along an axis () common to the two planes, r being a scalar comprising the lowest admissible value and the highest admissible value of the contribution of one of the coplanar subsets to the component of the setpoint angular momentum along the axis common to the two planes, determining a tilt angle value of each gyroscopic actuator of a subset, from the angular momentum to be provided by said subset, and Issuing a command to each gyroscopic actuator comprising the respective tilt angle value determined.Figure from the summary: Figure 2.

The invention discloses a dimension reduction method for river hydrodynamic simulation. The method comprises the following specific steps: collecting data information; constructing a planar two-dimensional hydrodynamic model based on a shallow water equation; the influence of curvature-induced secondary flow is added into a shallow water equation in a dispersion stress term mode; further introducing the contribution of the density gradient to the angular momentum into an angular momentum conservation equation; coupling a convection-diffusion equation considering dispersion stress, and constructing a planar two-dimensional hydrodynamic force-substance transport finite element model; and calculating a water depth average flow field and secondary flow intensity. According to the method, the three-dimensional effect of the secondary flow jointly driven by streamline bending and density difference is added into the two-dimensional equation in a dispersion stress term mode, the shallow water equation and the transport equation are solved in a coupling mode, the simulation precision of the two-dimensional model is greatly improved, and rapid and high-precision simulation of long-term evolution of the landform of a large river system is achieved.

The embodiment of the application discloses a kind of OAM mode determination method and device thereof, the method includes: sending the measurement reference signal corresponding to candidate OAM mode to receiving equipment;At least one measurement result of the measurement reference signal sent by receiving equipment is received;Target OAM mode is determined from candidate OAM mode based on measurement result, and it is indicated to receiving equipment.The embodiment of the application provides a kind of OAM mode determination method, by sending the measurement reference signal corresponding to candidate OAM mode, can make receiving equipment to measurement reference signal measurement, obtain measurement result, and then based on measurement result, the interference degree that signal on candidate OAM mode is judged, determines the most suitable target OAM mode, to reduce the interference between mode, improve system capacity.

This application relates to a satellite orbit prediction method. The method includes: constructing an expression for the gravitational force acting on the satellite based on its mass and distance from Earth; constructing a differential equation for the satellite's acceleration based on Newton's second law and the expression for the gravitational force; solving the differential equation based on the conservative force field characteristics of mechanics, calculating the gravitational potential energy function and its derivative with respect to time; transforming the derivative expression based on the mechanical conservation law that the sum of the derivatives of kinetic energy and gravitational potential energy with respect to time is zero, to obtain the derivative expression for acceleration; converting the time relationship in the derivative expression of acceleration to a radial position relationship based on the principle of conservation of angular momentum; integrating the radial position relationship to obtain the satellite's orbit equation. This method enables satellite orbit prediction.

The invention relates to a satellite orbit prediction method. The method comprises the following steps: constructing an expression of gravity borne by a satellite according to the mass of the satellite and the distance between the satellite and the earth; constructing a differential equation of the acceleration of the satellite according to the Newton's second law and the expression of the gravity borne by the satellite; solving the differential equation according to conservative force field characteristics of mechanics, calculating a gravitational potential energy function and a derivative expression of the gravitational potential energy function relative to time, and converting the derivative expression based on a mechanical conservation law that the sum of derivatives of kinetic energy and gravitational potential energy relative to time is zero to obtain a derivative expression of acceleration; according to the angular momentum conservation principle, the time relation in the derivative expression of the acceleration is converted into the radial position relation, integration is conducted on the radial position relation, and an orbital equation of the satellite is obtained. By adopting the method, satellite orbit prediction can be realized.

The application discloses a LS+CNN combined UT1-UTC prediction method considering effective angular momentum, relates to the field of geophysics and related computer science technology, and comprises the following steps: acquiring a UT1-UTC basic data set and an effective angular momentum data set, constructing an LS model and a CNN model, combining an LS fitting extrapolation result with an output result of the CNN model, and obtaining a high-precision UT1-UTC prediction value. The model has high precision and reliability in long-term UT1-UTC prediction, can overcome the shortcomings of a traditional linear model in UT1-UTC parameter prediction, and improves the prediction precision and stability of UT1-UTC compared with the traditional method. The method realizes high-precision long-term UT1-UTC prediction, and provides a new UT1-UTC parameter prediction method for the fields of navigation satellite orbit determination, astronomical observation and geophysical research.

The present invention discloses a method for angular momentum management based on a vector electric thruster. First, a linearized dynamic model for angular momentum management of the vector electric thruster is established according to the geometric structure, installation position, installation matrix and working combination of the vector electric thruster. Then, the control torque error term is estimated in real time through closed-loop feedback and compensated during the calculation of the angular momentum to be managed, and the rotation angle command of the vector electric thruster is calculated through hysteresis control and pseudo-inverse distribution algorithm. Finally, a geometric reduction processing method for the vector electric thruster exceeding the misalignment mechanism limit threshold is given. By linearly simplifying the dynamic model, the present invention reduces the computational amount of the angular momentum management method, and improves the angular momentum management accuracy by considering the introduction of closed-loop estimation of the control torque error. Hysteresis control and pseudo-inverse distribution reduce the adjustment times and adjustment amplitude of the misalignment adjustment, and reduce the influence on the attitude and orbit control accuracy.

The present invention provides a satellite electric propulsion system, including: electric thrusters, the number of which is four, each of which is installed on the satellite back floor through a dual-axis vector adjustment mechanism, and its thrust direction points to the center of mass of the satellite, wherein: two electric thrusters are arranged on each side of the satellite back floor, symmetrically installed relative to a center line of the satellite back floor; the two electric thrusters on the same side are symmetrically installed relative to another center line of the satellite back floor; the satellite back floor is rectangular. The angular momentum unloading method, used for the above-mentioned satellite electric propulsion system, includes: initializing the dual-axis vector adjustment mechanism and angular momentum unloading. This scheme can complete the angular momentum unloading of the momentum wheel while the electric propulsion performs position holding, and improve the efficiency of the use of propellant, which can meet the on-orbit angular momentum unloading requirements of GEO satellites. This patent is applicable to geosynchronous orbit satellites that use electric thrusters for angular momentum unloading.

The invention belongs to the field of space assembly motion analysis, and particularly relates to a mechanical arm connection assembly attitude analysis method. The method comprises the following specific steps: 1, acquiring the position, the speed, the attitude and the angular speed of a manipulated target under a body coordinate system; 2, according to the relative position, calculating the center of mass of the combination body and establishing a combination body coordinate system parallel to the body layout system; and calculating an assembly inertia tensor under the assembly coordinate system according to the relative attitude. And 3, analyzing an angular momentum kinematics formula of the combination during relative rotation of the target, and deducing a reaction torque generated by relative rotation. And 4, analyzing the angular momentum of the combination when the configuration changes, and deducing the moment generated by the configuration changes. And 5, after the moment is superposed, the attitude angular velocity of the combination is calculated according to the inertia tensor, and integration is carried out to obtain the attitude angle of the body with the layout system parallel to the combination system. The method can improve the simulation precision and reliability of a kinematics analysis system based on angular momentum conservation, and has been applied to in-orbit satellite ground tests.

The embodiment of the present disclosure relates to a single-frame control moment gyro group on-orbit singularity analysis method. The method comprises the following steps: obtaining an angular momentum vector of an SGCMG based on each frame angle of the SGCMG, and establishing an angular momentum output equation of the SGCMG group; obtaining an output torque equation of the SGCMG group and a torque matrix of the SGCMG group according to the angular momentum output equation; obtaining a singular standard of the SGCMG by using the torque matrix and a singular frame angle of a singular state, and judging whether the frame angle is a singular point; if the frame angle is the singular point, judging the type and the singular direction of the singular point; drawing according to the singular direction and the angular momentum output equation; constructing a PID control model of the SGCMG, and simulating and analyzing a singular influence mechanism of the SGCMG group. According to the embodiment of the present disclosure, the visual drawing and the mechanism simulation running can directly show the singular point space distribution and changes of the SGCMG after the abnormality, and the spacecraft attitude maneuvering performance changes of the SGCMG group under external force interference can be accurately obtained.

The invention discloses a method for determining an available angular momentum space during partial failure of a control moment gyroscope group. The method can be applied to a control moment gyroscope group control system with a pentagonal pyramid structure. According to the method, the shape and the position of an angular momentum available space when only three control moment gyroscopes in the six control moment gyroscopes are available are given. According to the method, complex trajectory optimization and singular avoidance problems are simplified into simple geometric problems, and finally a visual analysis structure is obtained and can be directly used as binding parameters for on-satellite calculation.

The application discloses a kind of unloading method and device of asymmetric configuration satellite angular momentum, the method includes: by solar sensor, the solar vector under satellite body system is acquired, and the solar vector is converted into the solar vector under orbit system;The included angle β of the solar vector under the orbit system and orbit plane is calculated, and the rotation angle of solar wing rotation axis and the preset angle of biasing axis are set according to the included angle β of the solar vector under the orbit system and orbit plane;The angular momentum of flywheel system is calculated and is converted into the angular momentum under satellite body system;According to the modulus of satellite to be unloaded angular momentum and preset unloading threshold value are compared, according to the comparison result, it is judged whether magnetic moment device unloading needs to be started, and according to the comparison result, the control instruction of magnetic moment device is output.The application effectively reduces angular momentum accumulation and space moment accumulation;With the advantages of saving fuel, low power consumption requirement and high attitude stability, it provides a theoretical basis for angular momentum unloading of weak magnetic field planet explorer.

The application discloses a kind of two-way spin angular momentum and momentum direction controllable single photon emitter and method thereof.The application independently controls the spin angular momentum of emitting photon by the internal structure of each nano scattering unit, and is irrelevant to the phase of scattered light;The momentum direction of emitting photon is controlled by the position of each nano scattering unit, and is related to the phase of scattered light, two kinds of control do not affect each other, and the control of the spin angular momentum and momentum direction of emitting photon can be independently designed;Two sets of super surface structures corresponding to two emitting photons are combined to form a two-way single photon emitter, and single photon emission is realized, and the spin angular momentum and momentum direction of each emitting photon can be independently controlled by the corresponding super surface structure;The maximum emission angle can reach 53°, and the phase-independent scheme makes the spin angular momentum insensitive to the accurate position of single photon source relative to the super surface, so high-precision single photon source positioning and alignment technology is no longer needed.

Method for detecting local orbital angular momentum of a complex-structured beam under a finite aperture. First, under the condition of a finite receiving aperture, the calculation method of the orbital angular momentum of the structured beam of the locally received energy is supplemented, filling the blank of the method for detecting the local orbital angular momentum of a complex radially structured beam under a finite receiving aperture. Second, according to the characteristics of the orbital angular momentum distribution of the complex radially structured optical field, the orbital angular momentum corresponding to each intensity ring of the complex radially structured optical field is refined. The present invention solves the calculation and detection of the local orbital angular momentum of a complex radially structured beam under a finite receiving aperture, and achieves the detection of the local orbital angular momentum of the complex radially structured optical field by extracting the radial position of the local optical field of the complex radially structure.

The invention relates to a model prediction power tracking control method for a multistage compressor system, and aims to improve the power tracking precision and control performance of a multistage compression energy storage system. Based on the principles of mass conservation, momentum conservation and angular momentum conservation, a fine state space dynamic model of a multistage centrifugal compressor system is established, the coupling effect between compressors is considered, and a ternary function of pressure ratio and isentropic efficiency is fitted through a semi-empirical formula in combination with measured data. A complex nonlinear system is converted into a simplified model suitable for MPC by simplifying a conversion process, constructing a kinetic model of a compressor and adopting linearization and discretization processing based on an augmented state space model, and an MPC control strategy considering safe operation constraints is designed to realize system power tracking. In the power tracking process, the state quantity and control quantity constraints of the system are considered, and the control target is optimized. The method can be widely applied to power regulation and optimization control of the multi-stage compression energy storage system.

The invention discloses a plasma state active control platform and method based on an orbital angular momentum electromagnetic field, and belongs to the technical field of plasma control. The platform comprises an orbital angular momentum electromagnetic field generation module, an energy and mode coupling module, a plasma region, a plasma state sensing module and a feedback control module. All the modules jointly form a closed-loop control structure, and through angular momentum exchange between an orbital angular momentum electromagnetic field and plasmas, active regulation and control over the macroscopic state, spatial distribution or statistical characteristics of the plasmas are achieved. The method does not depend on a specific device structure, a working frequency band or an implementation mode, has the advantages of being high in response speed, high in control dimension, high in adaptability and the like, and is suitable for a magnetic confinement nuclear fusion device, industrial plasma processing equipment and other plasma systems.

The present invention discloses an azimuth angle measurement method based on underwater acoustic orbital angular momentum, which is applicable to the application field of vortex waves carrying orbital angular momentum. The method is based on the wavefront distribution characteristics of vortex waves carrying special orbital angular momentum. Two coaxially transmitted superposition waves with orbital angular momentum having the same topological charge value but opposite signs and having a rotational angular velocity are generated by a uniform circular array, so that the azimuth angle of the "dark diameter" of the superposition wave in the signal receiving plane changes uniformly. A data signal received by a single target receiver located in the signal receiving plane is analyzed and processed to obtain a low-frequency signal containing envelope information of the received data signal, which is then correlated with a reference signal to obtain the peak position of the spectrum line. Finally, the target azimuth angle is calculated through the formula relationship between the peak position of the spectrum and the azimuth angle.