37 results about "Nonlinear saturation" patented technology

An RF receiver which produces quadrature digitized outputs and has a gain control is coupled to a digital gain controller which converts the quadrature digitized outputs into an rms voltage, and iterates over a finite number of steps to quickly control the gain to a level sufficient to achieve subsequent digital signal processing without limitations caused by insufficient dynamic range or nonlinear saturation effects caused by insufficient signal or excessive signal at the A/D input, respectively.

A servo system adaptive sliding mode control method based on an extended-state observer comprises establishing a servo system model, initializing a system state and a control parameter, performing approximate compensation on a saturation link, designing a non-linear extended-state observer, determining an observer parameter by utilizing a pole placement method, and designing an adaptive sliding mode controller. The extended-state observer is designed and is used to estimate the system state and uncertain items comprising system friction and an external disturbance, and the observer gain parameter is determined through adoption of the pole placement method; and the adaptive sliding mode controller is designed, a system tracking error is guaranteed to be rapid and stable and to converge to zero, and rapid and stable control of a servo system is finally achieved. The problem that the system friction and other external disturbances are unmeasured is solved, a non-linear saturation link influence existing in the system is compensated, a buffeting problem existing in an ordinary sliding mode method is improved, robustness of the system is enhanced, and the system can rapidly and stably track a desired signal.

The invention provides an anti-saturation self-adaptive pseudo-proportion integration differentiation (PID) sliding mode fault-tolerant control method for a high-speed train and the method can improvethe effect of tracking a desired track of a high-speed train. The method includes the following steps: establishing a high-speed train dynamic model having an actuator fault, actuator asymmetric nonlinear saturation constraint and integral quadratic disturbance; giving the position and speed of a desired track, and establishing a desired track model; establishing an actuator auxiliary saturationcompensation system; based on the established high-speed train dynamic model, desired track model and actuator auxiliary saturation compensation system, calculating a track tracking error; based on the calculated track tracking error, constructing a pseudo-PID sliding mode surface; and based on the constructed pseudo-PID sliding mode surface, determining self-adaptive control laws, wherein the self-adaptive control laws include: a nominal control law for realizing exponential stability, a compensation control law for suppressing actuator faults and the influence of integral quadratic disturbance, and a self-adaptive law. The invention relates to the technical field of rail transportation control.

A system includes a parameter generation system to determine at least one parameter for an injection procedure (for example, a parameter of an injection protocol or an imaging system parameter), the parameter generator system includes a physiologically based pharmacokinetic model to model propagation of a contrast medium injected into a patient including at least one of a non-linear saturation term in a peripheral venous compartment, at least one configurable transport delay term through at least one compartment, or an adaptation to model volumetric flow rate of blood and an effect thereof on the propagation of contrast medium after injection of contrast medium ceases. The physiologically based pharmacokinetic model can, for example, be discretizable.

The present invention relates to a device and to a method for determining position information of the rotor shaft of an electric machine on the basis of at least one input signal received by the electric machine, wherein the received input signal is supplied to a model of the electric machine. The position information of the rotor shaft is determined by means of the model based on the supplied input signal, wherein the model represents non-linear saturation effects of the electric machine. The model of the electric machine is an expanded Kalman filter in which the non-linear saturation effects of the electric machine are described by a polynomial.

The invention provides a double-rigid-body characteristic point saturation fixed time relative pose tracking control method. The method comprises the steps: establishing a pose kinetic equation of a tracker and a target device based on a Newton-Euler method; establishing a relative pose kinetic equation considering model uncertainty according to the established respective pose kinetic equations ofthe two rigid bodies and the relative pose and the relative speed between the two rigid body feature points; designing a fixed time disturbance observer according to the established relative pose kinetic equation; designing a non-linear saturation compensator according to the established fixed-time non-singular terminal sliding variable so as to solve the saturation effect of an actuator; and combining the established fixed-time disturbance observer and the nonlinear saturation compensator to obtain a model-based robust adaptive controller. The invention relates to the field of control of anautonomous moving body in a three-dimensional space and spacecrafts.

The invention provides an active disturbance rejection control optimization method for a permanent magnet synchronous motor (PMSM) based on model reference adaptive and belongs to the field of inductive control of the permanent magnet synchronous motor. The method is characterized in that through pre-establishing a mathematical model of the PMSM, firstly, an inertia estimation observer is utilizedto observe the inertia of a system, secondly, external load disturbance is observed through an extension state observer, and lastly, load disturbance is compensated to system input. The method is advantaged in that the improved sigmod function is used for a nonlinear saturation function of the extension state observer, the feedback section utilizes the improved sigmod function for nonlinear PD control, parameters are easy to set, the inertia and the load can be observed online in real time, and the system is robust.

The invention discloses a self-starting mode-locked fiber laser for polarization state stability control. The self-starting mode-locked fiber laser is characterized by comprising a pumping source 1, a wavelength division multiplexer 2, a gain fiber 3, a non-gain fiber 4, a polarization controller 5 and a polarization beam splitter 6 which are connected with one another in sequence, wherein the wavelength division multiplexer 2 is used for coupling pumping light and reflected light into a light path; the gain fiber 3 is used for generating inverted population required by laser; the non-gain fiber 4 is used for controlling the repletion frequency of the laser; the polarization controller 5 is used for changing a laser polarization state; and the polarization beam splitter 6 is used for dividing the laser into two beams. One laser output end of the polarization beam splitter 6 is connected with a saturable absorber 7 for generating nonlinear saturated absorption to realize mode-locked self-start, and the other laser output end of the polarization beam splitter 6 is a polarization-preserving output end; and the reflecting light of the saturable absorber 7 enters the wavelength division multiplexer 2 through the polarization beam splitter 6. The self-starting mode-locked fiber laser has the advantages that the mode-locked pulse sequence is more stable, the anti-interference capability is stronger, the laser can stably run for a long time, and the like, and the output of pulse laser with different repetition frequencies and center wavelengths is realized.

The invention provides a device for improving properties of light spots of a super-resolution phase board. The device is characterized by consisting of a three-ring pure-phase type super-resolution phase board, an object lens with a numerical aperture NA of 0.95, and a Sb2Te3 non-linear saturated absorption thin film in sequence along a light beam forward direction; normalized radii of the three-ring pure-phase type super-resolution phase board are r1 of 0.13, r2 of 0.47 and r3 of 1 respectively; phases of three areas respectively are phi1 of 0, phi2 of pi, and phi3 of 0; the object lens is tightly adhered to the three-ring pure-phase type super-resolution phase board; the Sb2Te3 non-linear saturated absorption thin film is located on a focal plane of the object lens; the thickness of the Sb2Te3 non-linear saturated absorption thin film has a selection range of 10-100 nm; and a linear absorption coefficient and a non-linear absorption coefficient of the Sb2Te3 non-linear saturated absorption thin film respectively are alpha0 of 5*10<7>/m and beta of -2*10<-2>m/w respectively. According to the device provided by the invention, the light spots and sidelobes are further reduced and a focal depth is lengthened.

Embodiments of the present invention disclose a waveguide structure, an optical device, and a method for manufacturing the waveguide structure. The waveguide structure comprises: a first dielectric layer; a core layer stacked on the first dielectric layer, wherein the refractive index of the core layer is greater than the refractive index of the first dielectric layer; a second dielectric layer stacked on the core layer, wherein the second dielectric layer comprises a groove, the opening of the groove faces away from the core layer, and the refractive index of the second dielectric layer is smaller than the refractive index of the core layer; and an absorption layer covering the outer surface of the second dielectric layer, wherein the absorption layer is in contact with the side wall of the groove and the bottom of the groove, and the absorption layer has a non-linear saturation absorption property.

The invention relates to a semiconductor laser with high single longitudinal mode stability. The semiconductor laser is characterized in that a passive detuning double-grating area is introduced into a traditional FP laser, and a nonlinear saturation effect of a gain medium of a Fabry-Perot cavity is used as a nonlinear gain element, so that a novel semiconductor laser is constructed. A frequency spectrum is purified through the high-Q band-pass filtering of a detuning double-grating area and according to the intrinsic multi-lasing mode of the FP cavity, then the frequency spectrum is slightly broadened through the amplification of the nonlinear gain medium of an active area of the FP laser, and the operations are repeated, so that the frequency spectrum of the laser is greatly narrowed after multiple times of filtering, and finally the single-mode lasing oscillation is formed.

The invention provides a fabrication method of a micro-nano structure and a system used in the fabrication method. The fabrication method comprises the following steps: a substrate is provided and a phase change film is formed on the substrate; a non-linear saturated absorption film is coated on the phase change film; laser is used to pas through that nonlinear saturation absorption film, and thephase change film is exposed according to a predetermined pattern; and the exposed phase change film is developed using a developer, and the nonlinear saturation absorption film is removed at the sametime. According to the method, the nonlinear saturate absorption film is arranged to cover the phase change film, laser passes through the nonlinear saturated absorption film and the phase change film is exposed to fabricate the micro-nano structure, thus a laser beam is more concentrated, light spots are shrinked and the precision of the micro-nano structure is improved; and on the other hand, femtosecond laser is selected as a laser source, the thermal effect of laser is prevented from affecting the unexposed area, and thus the precision of the micro-nano structure is further improved.

The invention relates to a Co-bis-imidazolyl metal frame compound, a preparation method and application thereof. The metal frame compound has a chemical formula of {Co2(1, 2-BIB)(BTC)}n, wherein 1, 2-BIB is 1, 2-methylene imidazolyl benzene, and BTC is deprotonated 1, 2, 4, 5-benzenetetracarboxylicacid. The compound provided by the invention has the characteristics of simple and easily operated preparation method, low cost, stability below 230DEG C, and very strong third-order nonlinear optical saturated absorption performance, with a third-order nonlinear saturated absorption coefficient beta of -4.55*10<-6>m/W and a third-order nonlinear polarizability x<(3)> of 7.33*10<-8>es, the material can be widely applied to in laser pulse compression (Q switch and mode locking) and other fields.

The invention belongs to the field of non-linear differential game control, and provides a random non-linear differential game control method based on statistic linearization. The random non-linear differential game control method based on the statistic linearization comprises the following steps of: carrying out similar linearization on a system non-linear function by using a statistic linearization technology according to system state random probabilistic nature, and deriving with a random dynamic programming method to obtain analysis controller containing a statistic linearization coefficient; and meanwhile, carrying out statistic linearization on a non-linear saturation function by considering a condition that a control mount in actual engineering is limited by saturation, so as to obtain an analysis controller in a saturation limited condition. The controller consists of two parts of a system state feedback part and a statistic linear coefficient feedback part. With the adoption of the method, the two-point boundary problem caused by solving a non-linear (partial) differential equation (set) can be effectively avoided; and the random non-linear differential game control problems can be more conveniently solved on the premise that certain solving accuracy is ensured, so that multiple functions which cannot carry out the linearization by using Taylor series expansion have possibility of carrying out the linearization. The method is particularly suitable for functions, such as phase step and saturation control and digital conversion switch which are most used on aircraft, and has strong popularization and application values.

The invention provides a starting impact current suppression method for an inductive coupling energy transmission system, which comprises the following steps of: firstly, establishing a mathematical model of the inductive coupling energy transmission system, calculating and setting the starting time ts of the system, selecting a proper triangular carrier frequency f, and then changing the duty ratio D according to the rule of a nonlinear saturation function within the starting time ts, so as to suppress the starting impact current of the inductive coupling energy transmission system. The method comprises the steps that a high-frequency inverter is connected with a triangular carrier wave and is compared with the triangular carrier wave to obtain a switching function d, when the switching function d is a logic high level, the high-frequency inverter adopts phase-shift control with the phase-shift angle being 0 degree, and when the switching function d is a logic low level, the high-frequency inverter stops working, and then the starting impact current of the inductive coupling energy transmission system is restrained. When the duty ratio D changes according to the rule of a nonlinear saturation function, the system oscillation time is obviously shortened, and the amplitude is reduced.