121 results about "Non linear behavior" patented technology

A surgical robotic system automatically calibrates tubular and flexible surgical tools such as endoscopes. By accounting for nonlinear behavior of an endoscope, the surgical robotic system can accurately model motions of the endoscope and navigate the endoscope while performing a surgical procedure on a patient. The surgical robotic system models the nonlinearities using sets of calibration parameters determined based on images captured by an image sensor of the endoscope. Calibration parameters can describe translational or rotational movements of the endoscope in one or more axis, e.g., pitch and yaw, as well as a slope, hysteresis, or dead zone value corresponding to the endoscope's motion. The endoscope can include tubular components referred to as a sheath and leader. An instrument device manipulator of the surgical robotic system actuates pull wires coupled to the sheath or the leader, which causes the endoscope to articulate.

A system for digitally linearizing the nonlinear behaviour of RF high efficiency amplifiers employing baseband predistortion techniques is disclosed. The system provides additive or multiplicative predistortion of the digital quadrature (I/Q) input signal in order to minimize distortion at the output of the amplifier. The predistorter uses a discrete-time polynomial kernel to model the inverse transfer characteristic of the amplifier, providing separate and simultaneous compensation for nonlinear static distortion, linear dynamic distortion and nonlinear dynamic effects including reactive electrical memory effects. Compensation for higher order reactive and thermal memory effects is embedded in the nonlinear dynamic compensation operation of the predistorter in an IIR filter bank. A predistortion controller periodically monitors the output of the amplifier and compares it to the quadrature input signal to compute estimates of the residual output distortion of the amplifier. Output distortion estimates are used to adaptively compute the values of the parameters of the predistorter in response to changes in the amplifier's operating conditions (temperature drifts, changes in modulation input bandwidth, variations in drive level, aging, etc). The predistortion parameter values computed by the predistortion controller are stored in non-volatile memory and used in the polynomial digital predistorter. The digital predistortion system of the invention may provide broadband linearization of highly nonlinear and highly efficient RF amplification circuits including, but not limited to, dynamic load modulation amplifiers.

A system for digitally linearizing the nonlinear behaviour of RF high efficiency amplifiers employing baseband predistortion techniques is disclosed. The system provides additive or multiplicative predistortion of the digital quadrature (I/Q) input signal in order to minimize distortion at the output of the amplifier. The predistorter uses a discrete-time polynomial kernel to model the inverse transfer characteristic of the amplifier, providing separate and simultaneous compensation for nonlinear static distortion, linear dynamic distortion and nonlinear dynamic effects including reactive electrical memory effects. Compensation for thermal memory effects also is embedded in the nonlinear dynamic compensation operation of the predistorter and is implemented parametrically using an autoregressive dynamics tracking mechanism. A predistortion controller periodically monitors the output of the amplifier and compares it to the quadrature input signal to compute estimates of the residual output distortion of the amplifier. Output distortion estimates are used to adaptively compute the values of the parameters of the predistorter in response to changes in the amplifier's operating conditions (temperature drifts, changes in modulation input bandwidth, variations in drive level, aging, etc). The predistortion parameter values computed by the predistortion controller are stored in non-volatile memory and used in the polynomial digital predistorter. The digital predistortion system of the invention may provide broadband linearization of highly nonlinear and highly efficient RF amplification circuits including, but not limited to, dynamic load modulation amplifiers.

A computer-implemented method for modeling and/or improving operational performance of an energy system includes providing a graphical user interface configured to allow a user to manipulate equipment icons into an energy system model representation, using modular, piece-wise linear equipment models to simulate non-linear behavior of equipment represented by the manipulated equipment icons to solve an energy system model represented by the manipulation, and displaying a solution of the energy system model.

A well-posed magnetic imaging method is disclosed that exploits the non-linear behavior of the characteristic time scale of the Neel relaxation for obtaining accurate high-spatial resolution images of magnetic tracers. The method includes placing an object in a selection field (static field) generated by three pairs of orthogonally arranged coil (drive coils), supplying prudently choice currents to the drive coils, a zero field voxel (ZFV) is formed that can be positioned anywhere in the local region of interest (ROI), switching the magnetizing field off, and collecting an image.

The invention relates to a method for the correction or compensation of individual differences between the conversion characteristics of the image sensors (11) and the processing units (12) of an X-ray detector which are connected thereto. It is assumed that a functional relationship in conformity with GW=F_i(L_ij(φ)) exists between the quantity of radiation (φ) entering the detector and the grey value (GW) resulting therefrom for a pixel (j, i), where Lij describes the approximately linear behavior of the sensor arrangement (10) and Fi the non-linear behavior of the processing unit (12). For the inverse value L_ij⁻¹ a linear model function is used and for the inverse value F_i⁻¹ a non-linear model function is used with parameters which can be calculated from calibration measurements with different radiation quantities (φ_k). During later operation of the detector these model functions can be applied to the grey values (GW) obtained in order to correct said grey values with a high precision and in real time, the storage space then required being small as a result of the use of a single non-linear inverse value for each column.

A system and method for controlling the gain in the forward signal path of a digital predistortion linearizer is disclosed. The loop gain of the predistortion system is driven to unity, where a separately controlled constant-gain observation path allows accurate gain control of the forward path. This is divided into digital gain from the predistortion function and analog gain from a Voltage Variable Attenuator (VVA) in the transmitter. The invention balances the distribution between these two domains in order to maximize dynamic range and minimize noise in the forward signal path. In order to distribute the forward path gain accurately, the characteristic of the VVA must be well known. Since these devices tend to be non-linear, with variable characteristic over temperature and batch, the invention compensates for this non-linear behavior by tracking the varying transfer characteristic of the VVA, giving a predictable local characteristic. Another aspect of the disclosed invention is the ability to operate with very low transmit power and loop gain levels, allowing accurate gain control during such scenarios as cell initialization, that require operation over a wide dynamic range.

The invention provides a variational integral-discretization Lagrange model-based Buck-Boost converter modeling and nonlinear analysis method. The invention relates to a Buck-Boost converter modeling and nonlinear analysis method. The method of the invention is used for solving the problem that operation of a discrete iterative model is complex because the calculated quantity of an established stroboscopic mapping model is large. The method of the invention is realized by the steps as follows: 1) establishing an Euler-Lagrange function; 2) establishing a Hamiltonian system equation; 3) exporting location momentum of a variational integral; 4) establishing a discrete Lagrange model; 5) exporting a Jacobian matrix characteristic value; 6) calculating non-linear behaviors of a stability region of the Buck-Boost converter and a first branch point of the Buck-Boost converter. The method of the invention is applied to the field of the Buck-Boost converter modeling and nonlinear analysis.

The invention discloses a characterization method of material fatigue, creep, and fatigue-creep interaction service life, and belongs to the field of service life prediction of aero-engine critical materials. The characterization method is used for solving service life characterization and prediction problems of materials under low cycle fatigue, creep, and fatigue-creep interaction conditions. According to the principles, a power function form service life prediction method non-linear behavior characterization capacity is established via fatigue-creep interaction, low cycle fatigue, and creeptests of materials at different holding time, and obtaining of effective holding time and normalization dimensionless service life via normalization calculation method. The characterization method iscapable of realizing accurate characterization of service life of materials under low cycle fatigue and fatigue-creep interaction conditions, and especially, consideration and accurate prediction ofcreep service life can be realized. The advantages of the characterization method are that consideration of both physical mechanisms and model implementation convenience is realized, and material lowcycle fatigue, creep, and fatigue-creep interaction service life characterization and prediction problems are solved effectively.

The propagation of a compressional wave in a reservoir rock causes the pore fluids to flow within the pores and pore connections; this internal flow of the pore fluid exhibits hysteretic and viscoelastic behavior. This nonlinear behavior is directly related to the viscosity of the pore fluids. Pore fluids that have higher viscosity like oil, after being disturbed due to a sudden change in pressure applied by a seismic impulse, require a larger time-constant to return to its original state of equilibrium. This larger time-constant generates lower seismic frequencies, and becomes the differentiating characteristic on a seismic image between the lower-viscosity pore fluid like water against the higher-viscosity pore fluid like oil. Mapping these lower frequencies on a seismic reflection image highlights the oil-bearing volume of the reservoir rock formations versus the volume of the reservoir rock formations saturated with water or gas.

Modem rotary machine production requires built-in fault detection and diagnoses. The occurrence of faults, e.g. increased friction or loose bonds has to be detected as early as possible. Theses faults generate a nonlinear behavior. Therefore, a method for fault detection and diagnosis of a rotary machine is presented. Based on a rotor system model for the faulty and un-faulty case, subspace-based identification methods are used to compute singular values that are used as features for fault detection. The method is tested on an industrial rotor balancing machine.

A system and a general method estimate figures of merit based on nonlinear modeling and nonlinear time series analysis. Terms in a nonlinear behavioral model that depend on nonlinear combinations of a fixed input signal value are precomputed, optimizing the behavioral model such that figures of merit are evaluated from a single short stimulus vector. The optimized nonlinear behavioral model can then be applied to evaluate figures of merit for multiple devices under test (DUTs) in a manufacturing line. A process continually verifies and adjusts the nonlinear behavioral model based on sub-sampling multiple DUTs in a manufacturing line and comparing their figures of merit based on nonlinear modeling with those based on conventional measurement procedures.

A laser driver circuit compensates for non-linear behavior of Vertical-Cavity Surface-Emitting Laser (VCSEL) devices. A VCSEL has an internal parasitic capacitance that is charged while the VCSEL is on. When the VCSEL turns off, this internal parasitic capacitor discharges, keeping the VCSEL on longer, increasing the physical turn-off or fall time. The laser driver circuit compensates for the slower fall time by modulating both anode and cathode terminals of the VCSEL as the VCSEL is turned on and off. Both plates of the internal parasitic capacitor are discharged at turn off, cutting the parasitic discharge time in half. A cathode driver transistor modulates the cathode voltage while a source-follower transistor modulates the anode voltage. A modulating current may be switched using a current mirror structure. Multiple source-follower transistors may be selectable in parallel, with switches to select the total anode current, allowing for programmable compensation of the fall time.

The invention relates to a process and a device for thermal measuring the flow rate (v) of a fluid (3). In conventional thermal sensors the heating power P is supplied in the form of rectangular pulses. According to the invention, the sensor means (1b) are supplied by a heating control (2b) with non-constant heating pulses having a sublinear build-up dynamics P(t). Thereby, a nonlinear behaviour of the threshold value time (t_S), until a threshold value temperature (T_m) is reached, as a function of the flow rate (v) can at least partially be compensated. Embodiments concern inter alia a build-up dynamics P(t) proportional to t^m and/or to a time-independent amplitude factor (1+R_S/R_I)⁻¹, wherein m is a Reynolds-number-dependent exponent and R_S, R_l are thermal transfer resistances. The advantages are an improved precision, a shorter measuring time and an enlarged measuring range for the flow rate v.

A system and method are disclosed for calibrating non-linear behavior using attenuated stimuli and responses which allows for calibration with unknown stimulus and less expensive sources and receivers. The device under test is stimulated with a signal and then an attenuated version of the same signal, so that non-linear differences between responses can be attributed to the device rather than the signal source. Alternatively, or in conjunction with attenuation of the stimulus, the output of the device at different response amplitudes can be selectively attenuated such that the receiver measures approximately the same amplitude. This allows non-linear differences between measurements to be attributed to the device rather than the receiver. Two or more different signal sources can also be used, where responses are measured for each signal individually and then for at least one linear combination of signals.

A multi-frequency bond-testing system using acoustic probes in conjunction with NDT/NDI inspection instruments. Bond-testing of test objects is carried out at multiple discrete frequencies to produce a single, combined amplitude C-scan. Alternatively, or in combination, the system provides a single, combined phase C-scan to enable proper interpretation of the C-scans. Amplitude and/or phase readings on test objects are normalized at the selected frequencies relative to tests performed on a defect-free object at those frequencies. In this manner, the non-linear behavior of a bond-testing probe over a frequency range chosen for a given inspection is compensated for. The invention enables providing more easily interpretable and sharper images which enable a more reliable and faster reading and identification of defects in the test objects.