456 results about "Impedance parameters" patented technology

Techniques are provided for use in controlling rate-adaptive pacing within implantable medical devices such as pacemakers or implantable cardioverter-defibrillators (ICDs). In one example, a force-frequency relationship is determined for the heart of the patient, which is representative of the relationship between cardiac stimulation frequency and myocardial contractile force. To this end, various parameters are detected for use as surrogates for contractile force, including selected systolic pressure parameters and cardiogenic impedance parameters. Rate-adaptive pacing is then controlled based on the detected force-frequency relationship to, for example, deactivate rate-adaptive pacing if the slope and/or abscissa of the force-frequency relationship indicates significant contractility dysfunction within the patient. In other examples, rather than deactivating rate-adaptive pacing, control parameters are adjusted to render the rate-adaptive pacing less aggressive. In still other examples, trends in the slope and/or abscissa of the force-frequency relationship are monitored to detect contractility dysfunction and/or heart failure and titrate medications accordingly.

A method and apparatus for automatically detecting and diagnosing lead-related conditions is provided. Specifically, relatively short-term and relatively long-term impedance parameters are determined for detecting an impedance trend indicative of a lead-related condition such as an open circuit, which may be due to a conductor fracture or poor connection to an associated implantable medical device, or a short circuit due to an insulation breach. Monitoring of multiple lead impedance parameters is performed to diagnose a lead-related condition based on a number of diagnostic criteria. Supplementary analysis of multiple lead impedance parameter trends may be performed to identify lead-specific conditions, such as metal ion oxidation induced insulation degradation. A lead-related condition diagnosis and supporting data are stored in memory for uplinking to an external device for review by a clinician. A recommended corrective action and/or a patient notification signal for a lead-related condition may optionally be provided.

A system to measure intracardiac impedance includes implantable electrodes and a medical device. The electrodes sense electrical signals of a heart of a subject. The medical device includes a cardiac signal sensing circuit coupled to the implantable electrodes, an impedance measurement circuit coupled to the same or different implantable electrodes, and a controller circuit coupled to the cardiac signal sensing circuit and the impedance measurement circuit. The cardiac signal sensing circuit provides a sensed cardiac signal. The impedance measurement circuit senses intracardiac impedance between the electrodes to obtain an intracardiac impedance signal. The controller circuit determines cardiac cycles of the subject using the sensed cardiac signal, and detects tachyarrhythmia using cardiac-cycle to cardiac-cycle changes in a plurality of intracardiac impedance parameters obtained from the intracardiac impedance signal.

In an apparatus and method for detecting incipient heart failure of a patient. Impedance signals reflecting volume changes of the right ventricle and/or the right atrium of a heart of the patient are obtained. The impedance signals are processed to determine a first impedance parameter substantially reflecting a volume of the right ventricle, and a heart failure status is determined based on the first impedance parameter, wherein a decreasing first impedance parameter is determined to be an indication of a deterioration of the heart failure status.

The invention belongs to related technical field of intelligent sensing, and discloses a high-compliance method for guiding a robot to cooperatively work by people. The method comprises the followingsteps: (1) a human-computer cooperation system is provided; (2) the robot is towed for demonstration; a six-dimensional force sensor and a motor encoder of the human-computer cooperation system respectively measure information of force applied by operators and the angle and the angle speed of each joint of the robot; and a computer obtains the terminal speed and pose of the robot through robot kinematics calculation; and (3) the robot motion position and pose desired by the operators at the next time are predicted by adopting a sparse bayesian learning algorithm based on the information obtained in the step (2); and the torque of each joint is compensated through online adjustment of impedance parameters of an impedance controller according to the predicting result and design of a linear secondary adjuster. The method improves the compliance and the demonstration precision of the robot, and reduces the demonstration difficulty of the operators.

A method of analyzing cardiac functions in a subject using a processing system. The method includes causing one or more electrical signals to be applied to the subject using a first set of electrodes, the one or more electrical signals having a plurality of frequencies. The method includes determining an indication of electrical signals measured across a second set of electrodes applied to the subject in response to the applied one or more signals. Following this, and for a number of sequential time instances, the method includes determining from the indicating data and the one or more applied signals, an instantaneous impedance value at each of the plurality of frequencies, and determining, using the using instantaneous impedance values, an intracellular impedance parameter. The intracellular impedance parameter over at least one cardiac cycle is the used to determine one or more parameters relating to cardiac function.

The invention relates to an inversion method for a stratum elasticity constant parameter of pre-stack seismic data in geophysical prospecting for petroleum. The method comprises the following steps of: acquiring seismic data, and processing the pre-stack seismic data; obtaining logging data and extracting angle gather seismic data to form all stacked data; performing horizon calibration on the seismic data and the logging data; inverting the seismic data which is stacked at different incident angles to obtain a wave impedance parameter; calculating a corresponding reflection coefficient; generating a logging and seismic data pair; calculating a weight function and a model parameter of a function mapping network model, an impedance parameter and an elasticity constant; and drawing an elasticity constant profile for reservoir lithologic identification, petroleum-gas prediction, oil-water interface determination and petroleum reservoir description. By the method, the elasticity constant can be calculated by the conventional inversion of the seismic data and the logging data; and the method has certain adaptability to the inversion of faults and pinch-out zones, a wide application range, high resolution, high calculation speed, high stability, high calculation accuracy and the characteristic of certain anti-noise property.

A method and apparatus are provided for inspecting a coated substrate such as a multi-layer coating on a substrate of a turbine airfoil. At each of a number of locations along the airfoil a number of frequencies of alternating current are passed through the airfoil. At least one impedance parameter is measured. The measured impedance parameters are utilized to determine a condition of the coating.

The systems and methods of the present disclosure calibrate impedance loss model parameters associated with an electrosurgical system having no external cabling or having external cabling with a fixed or known reactance, and obtain accurate electrical measurements of a tissue site by compensating for impedance losses associated with the transmission line of an electrosurgical device using the calibrated impedance loss model parameters. A computer system stores voltage and current sensor data for a range of different test loads and calculates sensed impedance values for each test load. The computer system then predicts a phase value for each load using each respective load impedance value. The computer system back calculates impedance loss model parameters including a source impedance parameter and a leakage impedance parameter based upon the voltage and current sensor data, the predicted phase values, and the impedance values of the test loads.

The invention relates to a portable impedance measurement instrument based on FPGA (field programmable gate array), belonging to the technical field of impedance measurement. The portable impedance measurement instrument based on the FPGA is characterized in that the impedance measurement instrument includes a microprocessor module, a sine signal generator module, a self-balancing bridge module, an automatic gain adjustment module, a phase sensitive demodulation module, a display module and a power supply module; the microprocessor module is connected with the sine signal generator module, the self-balancing bridge module, the automatic gain adjustment module and the phase sensitive demodulation module; the impedance measurement value is displayed by the display module; and the power supply module is used for supplying power to the circuit. The portable impedance measurement instrument has the advantages of simple measurement circuit, high integrity, high digital degree, small size and good portability, and is economic and practical, and can meet the requirement for impedance measurement in the common engineering field. The instrument can measure single parameters of impedance, capacitance and inductance or complex impedance parameters including resistance, capacitance and inductance, and can also achieve sweep frequency measurement.

The invention provides a method for selecting initial values of three-phase Newton-Raphson method power flow calculation of a power distribution network. The method comprises the following steps: S1, establishing a power distribution network three-phase system model; S2, establishing a power distribution network three-phase simplification system, and numbering nodes and branches of the power distribution network three-phase simplification system; S3, storing a three-phase load parameter of each node according to the serial number sequence of the nodes, and storing a three-phase impedance parameter of each branch according to the serial number sequence of the branches; S4, performing per-unit on the three-phase load parameter of each node and the three-phase impedance parameter of each branch; S5, establishing a power distribution network single-phase simplification system; S6, selecting convergence precision, performing power flow calculation on the power distribution network single-phase simplification system by a forward-backward sweep method to obtain the voltage amplitude and the phase angle of each node of the power distribution network single-phase simplification system; S7, selecting the initial value of the three-phase Newton-Raphson method power flow calculation of a power distribution network three-phase system. The method can select the initial value of the three-phase Newton-Raphson method power flow calculation by the forward-backward sweep method with high calculation speed and good convergence.

The invention discloses a crusting transient thermal impedance measuring method used for a high power IGBT. The method comprises the steps that an IGBT thermo-sensitive parameter calibration curve is acquired; junction temperature and case temperature cooling curves in an IGBT cooling process are acquired; and cooling curve deviation correcting and cooling curve fitting are carried out to acquire transient crusting thermal impedance parameters. According to the invention, a thermo-sensitive parameter method is used to measure the junction temperature cooling curve in the high power IGBT cooling process, and at the same time a thermocouple method is used to acquire the IGBT case temperature cooling curve; the IGBT transient thermal impedance parameters are acquired through curve fitting; and the method has the advantages of easy operation and wide use range, can directly and accurately acquire the transient thermal impedance parameters in the IGBT, and can be used to predict the junction temperature change trend in the actual operation of the high power IGBT for further thermal stability evaluation.

A method is provided for measuring D-Q impedance of a component of a polyphase power grid connected to a grid node, and evaluating the margin of stability at a node using Nyquist diagrams generated from the measured D-Q impedance data. A generator, coupled to the polyphase power grid, is controlled to induce suppressed-carrier stimulus current into the grid node. Circuitry measures response signals of suppressed-carrier form existing within a bus voltage at the grid node and a branch current of the component being measured. The method includes measuring complex voltage components of the response signals contained in the bus voltage and complex current components of the response signals contained in the branch current to form simultaneous equations that are resolved to determine the D-Q impedance parameters Zqq, Zqd, Zdq and Zdd of the measured component.

A robot includes a multi-joint robot arm, an external force acquiring unit arranged at the multi-joint robot arm to acquire an external force, and an impedance control unit that causes the multi-joint robot arm to operate as a virtual spring-mass-damper system based on the external force acquired by the external force acquiring unit. The impedance control unit has an impedance map storage unit that defines impedance parameters at each of points of the work region, and an impedance map variable unit that changes the distribution of the impedance parameters in the impedance map storage unit in accordance with the current arm end position or the current arm end velocity of the multi-joint robot arm.

A lithium battery dynamic impedance parameter identification method based on an equivalent circuit model is disclosed. Firstly, a charge/discharge system is made based on a first order RC equivalent circuit; a charge/discharge test on a to-be-tested lithium battery is carried out according to the charge/discharge system; and test data is obtained, and parameters are extracted. According to the invention, online estimation of dynamic internal resistance of a lithium battery in different charged states and charge/discharge conditions can be conducted, and a battery module which is simple and practical can be obtained on the basis. The invention takes correlation of impedance and charge/discharge current into consideration, improves the accuracy of lithium battery impedance parameter extraction, provides a simple and feasible charge/discharge test method and a specific parameter extraction algorithm, and has high practical operability.

A method of determining parameter values used in impedance analysis of a subject. The method includes using a processing system to determine a number of impedance measurements at a corresponding number of frequencies. The impedance measurements are used to determine estimates of parameter values, with the estimates being used to determine theoretical impedance values based on the parameter value estimates. The theoretical impedance values are compared to the measured impedance values to allow a modification direction to be determined for at least one of the parameter value estimates. This is then used to modify at least one parameter value estimate, with the parameter values being determined at least in part from one or more modified parameter value estimates.

The invention provides an anti-interference measurement method for the zero sequence impedance of a super-high-voltage/ultrahigh-voltage multi-loop power transmission line, which comprises the following steps of: firstly powering off the power transmission line; shorting and grounding three phases at the tail end of the line; shorting the three phases at the head end of the line; applying voltageto the head end of the power transmission line by directly using a single-phase power frequency power supply of a transformer substation where a voltage-application point of the power transmission line is located; and measuring zero sequence voltage applied to the head end of the power transmission line and zero sequence current applied to two ends of the power transmission line at the same time.In order to eliminate the influence of power frequency interference, when the zero sequence impedance is measured, harmonic components included in data of the measured zero sequence current and zero sequence voltage are utilized to calculate harmonic zero sequence impedance of the power transmission line, and finally the harmonic zero sequence impedance is converted into power frequency zero sequence impedance of the power transmission line.

The invention relates to a high-frequency electrotome generator based on an FPGA (Field Programmable Gata Array). A power supply provides direct-current voltage signals to a radio frequency generation module; the direct-current voltage signals are subjected to resonant amplification of the radio frequency generation module and rectification of a half bridge circuit to be changed to high-voltage alternating-current radio frequency singles to be output, and then the output signals are transmitted to a biological organization by a radiation electrode and a backward channel; an impedance detection unit is used for detecting the impedance of the biological organization and transmitting impedance parameters to an FPGA main control unit; according to the impedance parameters, the FPGA main control unit regulates the duty ratio of SPWM (Sinusoidal Pulse Width Modulation) waves in real time; and then the SPWM waves are output to the radio frequency generation module. A controller disclosed by the invention can realize accurate control and is high in response speed, easy to modify, capable of programming in situ, strong in universality and stable in performance; and more importantly, by virtue of the large-scale FPGA, a microprocessor, a special hardware algorithm unit, a special waveform generation unit and a signal acquisition and processing unit are all integrated on a single chip, so that the high-frequency electrotome generator becomes a special integral electronic control system.

The invention discloses a three-phase power flow correction method for a power distribution network containing distributed power sources. The method specifically comprises the following steps that a distributed power source three-phase model is constructed; a power distribution network three-phase system model containing the distributed power sources is established; nodes and branches in the power distribution network three-phase system model are numbered; three-phase load parameters of all the nodes in the power distribution network are stored according to the numbering sequence of the nodes, and three-phase impedance parameters of all the branches in the power distribution network are stored according to the numbering sequence of the branches; the three-phase load parameters of all the nodes and the three-phase impedance parameters of all the branches are subjected to per-unit treatment; problems existing in power flow calculation of the power distribution network containing the distributed power sources are analyzed, and the grid-connected voltage of the distributed power sources is corrected; convergence precision is selected, a power distribution network three-phase system containing the distributed power sources is subjected to three-phase forward-back substitution power flow calculation. According to the method, the characteristic that the output current and the grid-connected voltage of the distributed power source model are symmetric is considered, and a positive-sequence component of the network-side voltage is selected as the grid-connected voltage of the distributed power sources to participate in power flow calculation.

The invention discloses a frequency conversion transmission system motor side common code impedance extraction method. Through measuring time domain waveforms of a common mode voltage and a common mode voltage of a frequency conversion transmission system motor side and through subsequent mathematical calculation, a frequency spectrum characteristic of a frequency conversion transmission system motor side common code impedance is acquired. Compared to a traditional method of extracting an impedance parameter through an electromagnetic numerical calculation method and a network impedance analyzer, in the method of the invention, a complex motor or cable model does not need to be established and a process is simple and is easy to realize. During an impedance extraction process of the traditional method, a port impedance of a motor which does not work is extracted. And in the common code impedance extraction method of the invention, an influence of motor operation on the port impedance is considered so that a common mode current of a motor side can be accurately predicted.

The invention relates to a harmonic current estimation method under the condition of unknown harmonic impedance, and the method comprises the steps: taking a harmonic voltage as a measurement quantity and taking a harmonic current as a state quantity according to the statistic independence and super-Gaussian distribution characteristics of a harmonic current quick fluctuation quantity, and building a harmonic state estimation model comprising measurement noise; enabling the noise and impedance parameters in an ICA model to serve as unknown variables, enabling the harmonic current to serve as a hidden variable, and obtaining a harmonic current optimal solution which cannot be affected by noise through employing the variational Bayesian learning capability for unknown variables; neglecting linear load admittance according to the characteristic that the linear load admittance is far less than system side admittance, eliciting a harmonic current amplitude proportion coefficient, and determining the current amplitude. Compared with the prior art, the method can effectively eliminate the uncertainty of an independent component analysis algorithm and restores the amplitude of the harmonic current with no need of harmonic impedance parameters, obtains an estimated harmonic current, can effectively reduce the impact on the estimation result from measurement noise, and is stronger in robustness.

On the basis of the inverter-side current feedback control strategy, the invention presents a multi-inverter micro-grid harmonic resonance suppression method based on adaptive virtual impedance remodeling. The method includes a virtual impedance remodeling unit, a parameter adaptive adjustment unit and a grid impedance online detection unit. The virtual impedance remodeling unit can improve the output impedance characteristics of grid-connected inverters and inject certain damping components into a micro-grid. The parameter adaptive adjustment unit adaptively adjusts the control parameters ofthe virtual impedance remodeling unit and a current regulating controller according to the impedance parameters of the grid to maintain the stability of the system. The grid impedance online detectionunit provides the equivalent impedance of the grid as the input of the parameter adaptive adjustment unit. The method improves the characteristics of the current loop, and enables inverters to maintain stability under various grid impedance conditions. The method can solve the problems of complex control system, fixed control parameters and low efficiency of the regulation process in the existingmulti-inverter micro-grid system.

The invention relates to a method for inverting a Poisson ratio parameter of pre-stack seismic data in oilfield development reservoir prediction and oil-water interface recognition. The method comprises the following steps: firstly, carrying out the superposition of different shot-geophone distances on the pre-stack seismic data according to the size of the shot-geophone distance to form a plurality of superposed seismic data of the different shot-geophone distances; comparing the superposed seismic data of the shot-geophone distances to obtain the superposed seismic data of the near shot-geophone distance and the superposed seismic data of the far shot-geophone distance reflecting the change of an underground reservoir; secondly, realizing the spatial distribution of inter-well stratum wave impedance parameters through utilization of inversion of a seismic and well logging data combined wave motion equation; calibrating the inter-well stratum wave impedance parameter as speed parameters; and finally, calculating the speed ratio and the Poisson ratio parameter; and the method effectively utilizes routine seismic data and the well logging data, has certain adaptive capacity for inversion of faultage and a pinch-out zone, has large application range, high resolution, small calculation quantity, high calculation speed, good stability and high calculation precision and has the characteristic of certain anti-noise capacity.

The invention belongs to the battery identification and estimation field, and specifically relates to a method of estimating SOC (State of Charge) and impedance of a lithium battery on line. The method of estimating SOC and impedance of a lithium battery on line can improve the accuracy of a batter model equation so as to improve the accuracy of the Kalman filtering algorithm, by adding the impedance parameters, such as the direct current impedance, the polarized capacitance and the polarized resistance of the lithium battery, into the battery model equation, and can optimize the deficiency that the accuracy of the traditional Kalman filtering algorithm depends on the model accuracy. And at the same time, the method of estimating SOC and impedance of a lithium battery on line enables the dynamically changed impedance parameters to participate in every SOC estimation process, so that the estimated value of the battery residual electric quantity can have higher accuracy. At last, the method of estimating SOC and impedance of a lithium battery on line can obtain the reference value of the current healthy state for the lithium battery by referring to the corresponding battery electrochemistry impedance spectrum, thus being conductive to assisting the user to preferably master the current service life of the lithium battery by estimating the impedance parameters obtained through real time estimation. The method of estimating SOC and impedance of a lithium battery on line can realize high accuracy of estimating SOC and the service life of the lithium battery on line.

The invention discloses an SOGI-based single-phase transformer short-circuit parameter on-line real-time identification method. The identification method comprises steps of establishing a T-type equivalent circuit of a single-phase transformer; listing the short-circuit impedance parameter equation and the T-type equivalent circuit equation of the transformer; respectively obtaining the d axis equation and the q axis equation of the T-type equivalent circuit in a dq coordinate system; and using a SOGI-FLL model to extract fundamental wave components and fundamental wave orthogonal components of all input signals, obtaining the d axis component and the q axis component of all input signals in the dq coordinate system, and calculating the short-circuit resistance values Rk and Xk of the single-phase transformer, thereby achieving on-line monitoring of operation states of single-phase transformer windings. When windings of the transformer deforms and break down, the short-circuit impedance of the transformer will change. By measuring voltage and current of the primary side and the secondary side of the transformer, short-circuit parameters of the transformer windings can be identified. Thus, on-line monitoring of the operation states of the transformer windings is achieved; potential risks of the transformer can be found as soon as possible; fault points can be timely removed; operation accidents can be avoided; and service lifetime of the transformer is extended.

The invention provides a mobile mechanical arm position/force active disturbance rejection control method based on an adaptive algorithm. According to the method, a gradient descent method and an improvement process method are utilized according to a performance function, a parameter adaptive estimation algorithm is designed to adjust a target impedance parameter in real time, and a target impedance model can adapt to the external environment. Then, an impedance controller of a joint space is designed, an improved linear expansion state observer is utilized to estimate disturbance of a system,and compensation is carried out in the impedance controller. Simulation experiments show that the method can achieve accurate control over position/force under the condition that the external environment is uncertain.

A method of determining an index indicative of the presence, absence or degree of left ventricular hypertrophy in a subject. The method includes using a processing system to determine a measured impedance value for at least one body segment. For each body segment the measured impedance values are used to determine at least one impedance parameter, which are then used to determine a fat-free mass for the subject. The fat free mass can then be used as the index.