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82 results about "Discrete form" patented technology

Prediction model based hypersonic aircraft sliding-mode control method

The invention discloses a prediction model based hypersonic aircraft sliding-mode control method. The method is used for solving the technical problem of difficulty in engineering realization by existing hypersonic aircraft adaptive discrete control. The method includes: obtaining a strict feedback form of a height subsystem by reasonable assumption, and building a discrete form of an original system through an Eulerian method; building a four-step prediction model of the original system by unceasing forward prediction, wherein the model only includes an equation; enabling the prediction model to provide the relation of height output at a future time and current system state and control input, wherein the relation can be used for computing numerical values of lumped uncertainties of the system at the historical moment, and the numerical values are used for feedback design of a controller; and combining lumped nominal information further, and using a discrete reaching law to design the sliding-mode controller so that robustness of the system is improved. The prediction model based hypersonic aircraft sliding-mode control method has the advantages that the discrete prediction model is built to acquire system nominal and uncertain information, design of virtual control variables is not needed, the controller is simple and practical in design, and the method is suitable for engineering application.
Owner:NORTHWESTERN POLYTECHNICAL UNIV

Time scale function decomposition based hypersonic aircraft actuator saturation control method

The invention discloses a time scale function decomposition based hypersonic aircraft actuator saturation control method. The method is used for solving the technical problem of difficulty in engineering realization under the existing hypersonic aircraft actuator saturation condition. The method includes: obtaining a high-speed slow variable subsystem, a speed slow variable subsystem and an attitude fast variable subsystem by time scale decomposition, and building a discrete form of an original system through an Eulerian method; regarding the height and the speed in a fast subsystem design process as constants so as to achieve model simplification; considering actuator saturation limitations, and importing auxiliary control variables to design throttling valve openness and the controlpiston deflexion angle; and designing an updating law of a neural network by importing an auxiliary error variable. The time scale function decomposition based hypersonic aircraft actuator saturation control method has the advantages that computer control characteristics are combined, a discrete model is built, the subsystems are designed according to time scale function decomposition, the actuator saturation condition is fully considered during controller design, and the method is suitable for engineering application.
Owner:NORTHWESTERN POLYTECHNICAL UNIV

Method for simulating wide-band electromagnetic scattering property of conductor target

The invention discloses a method for simulating the wide-band electromagnetic scattering property of a conductor target. The method comprises the following steps that the geometric model of the conductor target is built, and mesh generation is conducted on the surface of the conductor target by a curved surface triangle unit; a time domain electric field integral equation of the conductor target is determined; a surface induction current in the time domain electric field integral equation expands through a space CRWG primary function and a time delay primary function; an expanding surface induction current expression is substituted into the time domain electric field integral equation, and then the time domain electric field integral equation in a discrete form is tested in a time and space mode so as to obtain a system impedance matrix equation; singularity integrals are eliminated to obtain a sparse expression of a impedance matrix; the equation of the impedance matrix is solved to determine the distribution of the time domain current of the surface of the conductor target, and wide-band electromagnetic property parameters of the target are obtained according to the distribution of the time domain current so as to finish simulation. The method for simulating the wide-band electromagnetic scattering property of the conductor target has the advantages of being high in simulation precision, little in required time and low in memory consumption, and has wide application prospect.
Owner:NANJING UNIV OF SCI & TECH

Method for controlling neural network of hypersonic aerocraft on basis of prediction model

The invention discloses a method for controlling a neural network of a hypersonic aerocraft on the basis of a prediction model, and belongs to the field of control for aerocrafts. The method is used for solving the technical problem of difficulty in engineering implementation of discrete adaptive control for an existing hypersonic aerocraft. The method includes obtaining a strict feedback form of a height subsystem by means of reasonable assumption, and creating a discrete form of an original system by an Eulerian method; building the four-step prediction model of the original system by means of continuous forward prediction; and adopting a lumped nominal design and error feedback for a controller and estimating and compensating lumped uncertain portions by the neural network. The four-step prediction model contains only one equation and provides the relation among height output at future moments, a current system state and control input. The method has the advantages that features of computer control are combined with the method, the discrete prediction model is built, virtual control variables are not required to be designed, only the neural network is required, and the method is suitable for engineering application.
Owner:NORTHWESTERN POLYTECHNICAL UNIV

Spacecraft multi-constrained attitude maneuver optimization method based on rotating path quality

ActiveCN109283934AGood for attitude tracking controlUnwind lowerAttitude controlAdaptive controlPath lengthKinematics
The invention discloses a spacecraft multi-constrained attitude maneuver optimization method based on the rotating path quality, and belongs to the technical field of spacecraft attitude planning andoptimization. The implementation method of the invention includes: establishing a rotating path quality evaluation model, and respectively giving a continuous form and a discrete form; evaluating therotation path quality by the reciprocal of the sum of the error distances of each path point and a target point; establishing a spacecraft attitude kinematics and dynamics model, and considering bounded constraints of the control torque and the angular velocity; determining a plurality of pointing constraints that the spacecraft needs to satisfy during the attitude maneuver; determining a startingattitude point and a target attitude point of the spacecraft attitude maneuvering process, and the starting angular velocity and the target angular velocity; solving the multi-constrained attitude maneuver based on the rotation path quality by using the optimization method, and obtaining the attitude path with high rotation path quality. The method can shorten the path length, reduce the path unwinding, obtain the attitude path with high rotation path quality, and is more beneficial to the actual attitude tracking control.
Owner:BEIJING INSTITUTE OF TECHNOLOGYGY

Method for identifying the discrete instantaneous angular speed of an electromechanical system

A method for identifying the discrete instantaneous angular speed of electromechanical systems in which electrical rotating machinery is used and in which at least one electrical signal is measured during an operation of the electromechanical system. The method includes measuring analog stator current signals and analog stator voltage signals for at least one phase A, B, C, converting the measurements into a digital discrete form, transmitting the digital discrete signals to a computer device wherein data analysis is performed in a processor unit on the basis of a simplified mathematical model of the dynamics of the motor or generator. During the data analysis an average rotor time constant is calculated, an average supply frequency value is identified, an average angular speed is obtained, and an instantaneous phase difference between the discrete stator current signals and the discrete stator voltage signals is determined. The discrete instantaneous angular speed is identified by combining the average supply frequency value, the instantaneous phase difference between the discrete stator current signals and the discrete stator voltage signals, the average rotor time constant, and a number of pole pairs of the electric motor, given by the user. The result of combining the data is stored in a memory of the processor unit.
Owner:ABB (SCHWEIZ) AG

Simulation method for rapidly extracting transient scattered signals of electric large-size metal cavity target

The invention discloses a simulation method for rapidly extracting transient scattered signals of an electric large-size metal cavity target. The simulation method includes creating a geometric model of the metal cavity target, and performing mesh dissection on the surface of the metal cavity target by a curved-surface triangular unit; determining a time domain integral equation of the metal cavity target; unfolding a surface induced current in the time domain integral equation by a high-order lamination divergence conformal basis function in terms of space and a time and space-time hybrid basis function in terms of time; substituting a surface induced current expression into the time domain integral equation, and testing a time domain electric field integral equation in a discrete form in terms of time and space respectively to acquire a system impedance matrix equation; solving the impedance matrix equation by a time stepping method, determining time domain current distribution on the surface of the conductor target, and acquiring broadband electromagnetic characteristic parameters of the target according to time domain current distribution to complete simulation. The method has the advantages of high simulation accuracy, less time used and low memory consumption, thereby having a broad application prospect.
Owner:NANJING UNIV OF SCI & TECH

Integral separation type PI-Type tight format model free adaptive course control algorithm used for ships

The invention belongs to the field of ship motion control, and specifically relates to an integral separation type PI-Type tight format model free adaptive course control algorithm used for ships. Thealgorithm includes the following steps: a proportional item is introduced to form a PI-type CFDL_MFAC algorithm based on the tight format model free adaptive control algorithm, and a discrete form ofthe proportional item is k

.[delta]e(k); a course deviation threshold e<0> is set; a course deviation e(k) is calculated, wherein e(k)=y<*>(k)-y(k); when an absolute value |e(k)| of the e(k) is greater than a threshold e<1> of a set course state deviation; according to the e(k), an integral separation type PI_CFDL_MFAC controller resolves expected input u(k) of a course system; and a formula ofk=k+1 is achieved, and a current course y(k) of a course ship is updated. By introduction of the proportional item in the control algorithm, the response speed of a system is improved; an idea of integral separation is introduced in the algorithm, thus avoiding the problem that an original control algorithm is directly applied to ship course control to cause system oscillation or even instabilitydue to integral saturation; and introduction of the proportional item and the integral separation idea makes an application range of a CFDL_MFAC theory extend, so that a ship course can quickly and stably converge to a desired course.

Owner:HARBIN ENG UNIV
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