96 results about "Limit cycle" patented technology

An apparatus and method for minimizing limit cycle oscillations within a switched power supply includes providing a programmable dither signal as an input to the digital control loop connected between an output and a control input of the switched power supply. The dither signal minimizes limit cycle oscillations from the output of the switched power supply.

The invention provides a heterogeneous database oriented massive multicast data storage implementation method. The heterogeneous database oriented massive multicast data storage implementation method comprises receiving multicast massages according to a certain limit cycle and quantity restrictions; storing the required messages into a first level cache data file and triggering the analysis on the first level cache data file through signals; storing the massages into corresponding models of second level cache data files and establishing second level cache data file storage catalogues and related data files and control files corresponding to the models; performing synchronous triggering of storage operation on models of storage threads according to the signals, performing analysis on the second level cache data files to be stored and inputting the analyzed data into corresponding databases through calling of an SQL * Loader and storage control file data. According to the heterogeneous database oriented massive multicast data storage implementation method, the real-time stable receiving processing of massive multicast data can be achieved, the synchronous efficient storage of multi-objective databases can be achieved, the processing capacity on the massive multicast data is improved in practical application, the integrity of the data is ensured, and the efficiency of the application system is improved.

A computer-implemented method of determining the pitch stability of an airfoil system, comprising using a computer to numerically integrate a differential equation of motion that includes terms describing PID controller action. In one model, the differential equation characterizes the time-dependent response of the airfoil's pitch angle, α. The computer model calculates limit-cycles of the model, which represent the stability boundaries of the airfoil system. Once the stability boundary is known, feedback control can be implemented, by using, for example, a PID controller to control a feedback actuator. The method allows the PID controller gain constants, KI, Kp, and Kd, to be optimized. This permits operation closer to the stability boundaries, while preventing the physical apparatus from unintentionally crossing the stability boundaries. Operating closer to the stability boundaries permits greater power efficiencies to be extracted from the airfoil system.

A finite state machine (FSM)-based biped robot, to which a limit cycle is applied to balance the robot right and left on a two-dimensional space, and a method of controlling balance of the robot. In order to balance an FSM-based biped robot right and left on a two-dimensional space, control angles to balance the robot according to states of the FSM-based biped robot are set. The range of the control angles is restricted to reduce the maximum right and left moving distance of the biped robot and thus to reduce the maximum right and left moving velocity of the biped robot, thereby reducing the sum total of the moments of the biped robot and thus allowing the ankles of the biped robot to balance the biped robot to be controlled, and causing the soles of the feet of the biped robot to parallel contact the ground.

A method for determining strictly-regressive orbit of a near-earth satellite is disclosed. The method comprises: on the basis that an orbit element prediction value of a regressive orbit in a low-order gravity potential field, combining an orbit semi-major axis a and an orbit inclination angle i, performing repeated iteration correction on the orbit semi-major axis a and the orbit inclination angle i according to the relationship of the orbit semi-major axis a and the orbit inclination angle i with the longitude and latitude of a sub-satellite point and based on an orbit recursion module of a high-order gravity potential filed module, combining an eccentricity ratio e and a perigee argument omega, and performing repeated irritation correction on the eccentricity ratio e and the perigee argument omega by employing an average process according to the characteristics of a vector limit cycle of the eccentricity ratio until the regression precision of an ascending node satisfies a preset value. The method determines the strictly-regressive orbit of the near-earth satellite based on high-precision orbit dynamics, the determined orbit possesses relatively high regression precision for a space target point, and compared with a conventional method based on a low-order gravity potential field, the high-precision orbit dynamics is relatively close to reality and possesses relatively high application value.

The invention discloses a method for suppressing the limit cycle of an inclination angle control system of an aircraft with parameter uncertainty. The method comprises the following main steps of: step 1, analyzing and establishing a model of the inclination angle system of the aircraft; step 2, analyzing scanning functions of a non-linear section and an oscillation phenomenon of the limit cycle; step 3, designing a controller of the inclination angle system of the aircraft with the parameter uncertainty; step 4, inspecting the performance of the controller; and step 5, ending the design. With the adoption of the method, not only is the oscillation of the limit cycle of the aircraft suppressed, but also the parameter uncertainty is overcome, and furthermore, the rapid and precise tracking to the inclination angle of the aircraft is realized. The method has better practical value and good application prospect in the technical field of automatic control.

The invention discloses a bifurcation frequency transfer control circuit in an inductive power transfer (IPT) system and a control method of the bifurcation frequency transfer control circuit. The bifurcation frequency transfer control circuit comprises a power module, a switching network, a primary side resonance compensating circuit, a transmitting coil, a receiving coil, a secondary side resonance compensating circuit and loads. The bifurcation frequency transfer control circuit is characterized in that a delayed interference module is connected on a controller, and the controller controls the working condition of the switching network according to a delayed interference signal output by the delayed interference module and a zero-cross signal output by a zero-cross detection circuit. The bifurcation frequency transfer control circuit has the advantages of being simple in circuit structure, convenient to control and free of the requirement for addition of excessive circuits on a main circuit. Only timely delayed interference needs to be added on a detection feedback signal. According to design of the bifurcation frequency transfer control circuit in the IPT system and the specific control method of the bifurcation frequency transfer control circuit, phase track flow of the IPT system can be restrained to a specified stable attractor of a limit cycle, and therefore stability and reliability of the IPT system are improved.

A switched voltage regulator provides improved regulation at a lower clock rate / sampling frequency (e.g. several orders of magnitude lower than would be required for comparable regulation) while using a low resolution digital pulse width modulator such that limit cycle oscillations occur (and thus of low cost and complexity and small size) by limiting the amplitude of limit cycle oscillations which therefore need not be avoided by more complex arrangements which are not commercially feasible. Limiting of amplitude of limit cycle oscillations is achieved by adding essentially a digitized ripple voltage signal corresponding to the difference between the output of the voltage regulator and an average output of the voltage regulator as an input to the digital pulse width modulator. Performance of this arrangement may be enhanced by adding a ramp signal to the digitized ripple voltage signal and even further enhanced by limiting the ramp signal to a range which corresponds to steady state operation but not transients.

The present invention provides a D / A converter circuit which enables D / A conversion with a high precision and can prevent occurrence of a limit cycle component in the case where an input signal is low, and can also prevent the effect of dither signal from occurring in an analog signal which is a D / A conversion result.A dither signal generation section 505 outputs a dither signal (DITHER) which is an alternating current signal and a reversal dither signal (DITHER_N) inverted from the dither signal. A DEM decoder 502 processes an input digital signal including a component of the dither signal (DITHER), and outputs a plurality of lines of time-series digital signals having a density of “1” or “0” conforming to the input digital signal to be processed. An analog addition section 503 converts a plurality of lines of time-series digital signals and the reversal dither signal (DITHER_N) into an analog signal respectively and adds them, and outputs an analog signal which is a D / A conversion result.

An apparatus and method for minimizing limit cycle oscillations within a switched power supply includes providing a programmable dither signal as an input to the digital control loop connected between an output and a control input of the switched power supply. The dither signal minimizes limit cycle oscillations from the output of the switched power supply.

The invention discloses a fast simulation algorithm of vibration response of an aerospace aircraft wing, and belongs to the technical field of aerospace, and relates to a vibration simulation technology of an aeroelastic structure. Modelling is conducted based on the fluid solid coupling problem encountered by the wing of an aircraft when the aircraft flies in a flow field in a high speed, and the method of using a new differential equation for solving the problem is proposed. The dynamic features such as the vibration and the limit cycle of an aerospace aircraft airfoil in a high speed flow field can be quantitatively investigated. The method establishes a precise and reliable mathematical model for the design of aerospace aircraft wings, and a novel fast effective time discrete method is applied in the investigation of the dynamic model of the non-linear airfoil, therefore all the dynamic features of the wings can be investigated. The method is applicable to the vibration simulation of the airfoils with strong non-linearity, and is high in efficiency and precision.

The invention discloses a hyper-chaotic signal source circuit of a hidden Lu system based on a memristor. A memristive term is added to a first equation of the original Lu system, and a linear feedback term and an external excitation term are added to a second equation. The system circuit comprises a memristor equivalent implementation circuit and an oscillating system. After the respective same ports of the memristor equivalent implementation circuit and the oscillating system are sequentially connected, the memristive system implemented does not have a balance point, can generate hidden oscillation phenomena of point attractors, periodic limit cycles, quasi-periodic limit cycles, chaotic attractors and hyper-chaotic attractors, etc., and can generate a hidden multi-attractor coexistencephenomenon of different periodic limit cycles or weak chaos and periodic limit cycles of a topological structure under different initial conditions, indicating that signals generated by a signal source have richer and more complex nonlinear dynamic characteristics. The system circuit facilitates circuit implementation and experimental observation, and is a new key signal generation circuit for chaotic secure communication.

The invention discloses a hidden multi-attractor generating circuit based on a non-equilibrium point memristive system realized by replacing a three-dimensional self-excited oscillation system with a voltage-controlled memristor to realize the linear coupling resistance at the input end of the integration circuit, including two parts: The voltage-controlled memristor equivalent realizes the circuit a and the three-dimensional self-excited oscillation system b; where the same ports of the circuit a and the circuit b are connected in sequence, the realized memristive system can present periodic limit cycles, quasi-periodic limit cycles, and chaotic attractors and hidden oscillation phenomena such as coexisting attractors. The circuit system is easy for numerical simulation, circuit simulation and experimental observation, and plays a great role in promoting the research and development of hidden multi-attractors.

Servocontrolled aerodynamic control surfaces, such as the direction rudder (1) of an airplane, are equipped with servoactuators (5). The bearing supports (3) of the rotation axis (2) or hinged axis give rise to the formation of free play for the manufacturing tolerances, that will be more pronounced with the wear of the bearings or joint elements. The mechanism (8) in question includes an elastic element (10) fixed to the structure (4) wherein the control surface (1) is jointed, connected rigidly to an articulated connecting rod (12) having a following roller (13) of a cam (9) integral to the control surface (1). The cam (9) profile produces a continuous nonlinear, angular deformation, of the elastic element in order to determine a force torque on the control surface (1) that is maximum in the neutral position of the control surface and manages to be eliminated in the extreme side deviations.

The invention provides a transonic limit cycle flutter analysis method. The transonic limit cycle flutter analysis method comprises the following steps: through equivalent linearization of a describing function, processing nonlinear characteristics of a transonic aerodynamic force; substituting a frequency-domain aerodynamic coefficient after the equivalent linearization into a flutter equation; obtaining a flutter speed and a flutter frequency by a frequency-domain flutter solving method; and for different limit cycle amplitudes, calculating to obtain different flutter speeds and flutter frequencies to form limit cycle characteristics of a transonic nonlinear flutter. The equivalent linearization is performed on the nonlinear characteristics of the transonic aerodynamic force through the aerodynamic describing function, the flutter equation is solved within a frequency domain, so that the flutter speed and the flutter frequency at a given limit cycle amplitude can be accurately predicted; and the transonic limit cycle flutter analysis method is moderate in computation amount, easy to master and very good in robustness.

The invention discloses a chaos control technique based bidirectional non-contact power supply system. The chaos control technique based bidirectional non-contact power supply system comprises a DC power supply U<H>, a full controlled bridge converter, non-contact transformers, a secondary-side converter, a filter circuit, a BOOST circuit, a charging switching device, a vehicle-mounted storage battery U<bat>, a primary-side controller and a secondary-side controller; in a positive transmission state, a mains supply acquires direct current through a power factor correction circuit, the vehicle-mounted storage battery is charged, and a solar cell also charges the vehicle-mounted storage battery; in a reverse transmission state, the solar cell supplies electric energy to a power supply side reversely, the cost is saved, and the volume and the weight are also reduced; in a positive power supply mode, a limit-cycle theory or a Poincare cross section is used for judging whether switching tubes S1 to S6 of the full controlled bridge converter work in soft switching states; in snow and rain days, a plug is not needed, and the safety performance is relatively high; and in a positive charging mode, three non-contact transformers are used, the power transmission range is larger, and the optimal state of the efficiency can exceed 94%.

The invention discloses a method for indicating terminal action time by a network side. The method solves the problem that the terminal action time cannot be indicated when the representation range of an action operating cycle is longer than that of a limiting cycle. The method comprises the following steps that: the network side maintains a base time segment serving as a scale, and the base time segment periodically and cyclically represents time by taking a frame as a unit; and the network side sends configuration information to a terminal, the configuration information carries cycle parameters and offset parameters, the cycle parameters are used for indicating the number of the cycles of the base time segment, and the offset parameters are used for indicating the frame numbers of occurrence in the cycle indicated by the cycle parameters.

The invention discloses an electrical servo system and a control algorithm thereof. Through setting a position proportion / integration calculating unit, a notch filter, a position feedback processing unit and a current control component, a "position / current double closed-loops+ specific section integration+ notch filter" algorithm of the electrical servo system is realized, and an accurate algorithm of the notch filter is provided, and thus the control difficulty that nonlinear part influence is obvious due to complex characteristics of the semi-closed-loop electrical servo system is overcome. The method can effectively suppress resonance peak of the electrical servo system and also eliminates limit cycle caused by gaps. Therefore, the electrical servo system and the control algorithm have very high engineering application values.

Disclosed is a method of defining control angles to use a limit cycle in order to balance a biped walking robot on a three-dimensional space. In order to balance an FSM-based biped walking robot right and left on a three-dimensional space, limit cycle control angles to balance the robot according to states of the FSM-based robot are set on the three-dimensional space, and the limit cycle control angles on the three-dimensional space are controlled using a sinusoidal function to allow relations between the control angles and control angular velocities to form a stable closed loop within a limit cycle.

The invention provides a food preparation machine with a current limiting net, comprising cup, head, wherein the head is mounted above the cup, and a blade is fixed on the front end of the major axis of the motor in the head and a current limiting net is set under the head. The upper part of the current limiting net is provided with a small current limiting hole and grip head and the bottom of the current limiting net is provided with a large current limiting hole. The food preparation machine has features of simple structure, easy preparation, convenient installation. The current limiting net is easy to disassembly and clean. The water and crushed material repeatedly perform current limiting cycle between the cup and current limiting net. The streamline passes the blade and the crushing effect is complete.

The invention provides a method for an unmanned aerial vehicle to track a water target based on time optimum. Assuming that state information of a to-be-tracked target is known, and that movement of the unmanned aerial vehicle in a horizontal plane and a longitudinal plane are decoupled, the method comprises the following steps: determining a tracking equilibrium state; based on the tracking equilibrium state, establishing an expected airway, guiding the unmanned aerial vehicle to operate on the expected airway, to guide the unmanned aerial vehicle to reach the tracking equilibrium state in shortest time. The method is also suitable to be used for tasks of a plurality of unmanned aerial vehicles to track a target, and barrier avoiding. The method for an unmanned aerial vehicle to track a water target guides the unmanned aerial vehicle to converge to a horizontal limit cycle and standoff height in shortest time through determining the tracking equilibrium state and establishing inner / outer tangent lines and critical height based on the equilibrium state, and task efficiency is relatively high.

The embodiment of the invention provides a method and device for determining the lateral motion stability of a high-speed train, the method comprising the steps of: obtaining a bogie frame lateral vibration acceleration signal of the high-speed train, low-pass filtering and band-pass filtering the bogie frame lateral vibration acceleration signal separately, and obtaining a determining index according to the low-pass filtered bogie frame lateral vibration acceleration signal, the band-pass filtered bogie frame lateral vibration acceleration signal, and respective corresponding preset time parameters; determining whether the high-speed train is instable or generates a hunting instability limit cycle bifurcation form based on the comparison of a first statistical bogie frame lateral acceleration movement root-mean-square value and a second statistical bogie frame lateral acceleration movement root-mean-square value with the respective preset threshold values. The device executes the above method. The method and device provided by the embodiment of the present invention can accurately determine the lateral motion stability of the high-speed train.

The invention provides an efficient linear radio frequency power amplifying device and method. The device comprises a radio frequency power amplifier used for amplifying a radio frequency signal, a self-adapting limit cycle circuit connected with the radio frequency power amplifier for performing nonlinear negative feedback control on the radio frequency power amplifier, a digital switch power supply respectively connected with the self-adapting limit cycle circuit and the radio frequency power amplifier for controlling the pulse signal to track the transient power self-adapting change of the radio frequency input signal, and a radio frequency band-pass filter connected with the output end of the self-adapting limit cycle circuit for demodulating the pulse signal and outputting the amplified radio frequency input signal, wherein the self-adapting limit cycle circuit inputs a radio frequency input signal and outputs a pulse signal having phase change modulated with the radio frequency input signal. The efficient linear radio frequency power amplifying device disclosed by the invention keeps the high efficiency and low power consumption, has the liner amplification function of bandwidth and large dynamic range so as to enable a base station to better realize high data transmission speed and coverage performance, effectively reduces the power consumption of a terminal and prolongs the service life of a battery.

A bus controller is provided including a processing means for performing processings of levels having cycle numbers which are different dependent on requesters which respectively issue an access request to a common memory. When it is expected from the present cycle number that a limit cycle number is exceeded, the bus controller selects a processing level with which the processing is performed with a smaller cycle number, or performs a control of giving no permission to a non-realtime bus access request. Thereby, it is possible to design a system with a cycle number that is smaller than the total sum of the maximum access cycle numbers multiplied by the maximum access times over all requesters.

A method and apparatus determines the presence of and source of instabilities, such as limit cycles, within a process control loop while the process control loop operates on-line within a process environment. The method and apparatus measures one or more signals within a process control loop when the process control loop is connected on-line within a process control environment, stores the measured signal as signal data and then performs one or more statistical analyses on the stored signal data to determine whether instabilities exist and, if so, whether the source of an instability is within a servo loop or outside of a servo loop and is due to friction, external forces or mechanical anomalies.

A method for on-line detecting industrial unstable time-lag process model includes separately recording down output array of relay and object and storing said array in random access storage when complete closed-loop system is entered into oscillation process, analyzing data to judge whether waveform outputted from object is limit cycle with stable oscillation or not, calculating out parameter of system model after key measurement information is stored in databank of computer if it is or otherwise regulating parameter of PD controller to make system output stable limit cycle and calculating out parameter of system model as per key information.

A method for damping aeroelastic modes, including limit cycle oscillations (LCO), is implemented by determining a mass for a tuned mass damper (TMD) based on an modal frequency for a mode having a potentially positive growth rate and attaching a TMD to at least one attachment point with significant motion such that a damping axis of the tuned mass damper is substantially oriented in a direction aligned with the local modal deflection.

A control apparatus includes a manipulated variable output unit, calculation unit, first lower limit setting unit, first upper limit setting unit, second lower limit setting unit, second upper limit setting unit, and controlling element. The manipulated variable output unit outputs first and second manipulated variables to an object to be controlled. The calculation unit calculates a limit cycle auto-tuning control parameter. The controlling element performs feedback control calculation based on the control parameter for the deviation between a set point and a controlled variable to calculate the first manipulated variable, and outputs the calculated first manipulated variable to the object. In executing limit cycle auto-tuning, the calculation unit outputs to the object the second manipulated variable having the second lower limit value as the lower limit value and the second upper limit value as the upper limit value, calculates the control parameter of the controlling element on the basis of a control response corresponding to the manipulated variable output, and sets the calculated control parameter in the controlling element.

Electrical stimulation to cardiac tissue stabilizes atrial and ventricular arrhythmia when timed to stabilize a limit cycle structure in a Poincare map. Disclosed are methods and apparatus, operational internally or externally, for removing the reentrant effects of heterogeneity present in a diseased heart and returning the heart to an improved metabolic status allowing removal of support. The methods and apparatus disclosed are also useful in the chronic surveillance and maintenance of regularized contractility in an aged or diseased heart.