137results about How to "Reduce nonlinear error" patented technology

An accurate calibration method of micro inertia measuring unit by decoupling erection error angle (EEA)with scale factor includes setting up MIMU integral error model and separating couple between EEA of accelerometer and gyroscope and scale factor ,using position error canceling method to calculate out and to separate out scale factor and EEA of accelerometer as well as using least square method and iteration method to calculate out EEA of gyroscope and its relative error items in 10 position static calibration test and in 3 direction positive and negative rate test ,then using interpolation method to calculate out scale factor of gyroscope .

A method for improving measurement precision by using an acousto-optic device in optical heterodyne interferometry belongs to the field of measurement precision by using acousto-optic device in optical heterodyne interferometry in precise measurement technology. In the measurement precision by using acousto-optic device in optical heterodyne interferometry by using the acousto-optic device, by changing the polarization direction of the part light beam output during an acoustic-optic interaction process, for instance, by utilizing abnormal Gragg diffraction, the polarization direction of the first-order diffraction light with frequency converted is vertical to other light beams, particularly the polarization direction of the zero-order light with the frequency unconverted; therefore, the crosstalk light is extremely easy to be filtered. Alternatively, the polarization direction of the reference light beam can be adjusted so that the polarization direction of the reference light component in the signal light beam is vertical to the polarization direction of the reference light beam, thus leading the interference signal output by a detector to be the minimum. In conclusion, the difference among the useful light beam, the crosstalk light and the noise light on the polarization direction can be caused; by utilizing the difference, the method can inhibit the effect of the interference light effectively, so as to reduce nonlinearity, improve signal-to-noise ratio and improve the measurement precision by magnitude.

A piezoelectric clamping micromanipulator with flexible drive and amplification and adjustable range is composed of microactuator, flexible multiplying mechanism, size pre-regulator, and clamping micromanipulator. Its advantages are compact structure, high reliability, and low non-linear error.

The present invention relates to a method and system for reducing integral non linearity errors in a pipeline Analog to Digital Converter (ADC). The invention provides in a first embodiment a method comprising the steps of: adding an analog dither signal to the analog input signal of a pipeline Analog to Digital Converter, and converting the analog input signal to a digital output signal by means of the pipeline Analog to Digital Converter. The amplitude of the analog dither signal is determined by the architecture of the Analog to Digital Converter. The invention also provides in a second embodiment a circuit comprising a pipeline analog to digital converter for converting an analog input signal to a digital output signal and a feedback circuit coupled to the converter such that the digital output signal is adapted to have an average non linearity error value of about zero LSBs.

The invention relates to an alternating current/direct current sensor. The alternating current/direct current sensor comprises a high-permeability transformer unit, an excitation signal generation unit, a direct current signal detection unit, a restoring circuit unit, an alternating current signal processing unit and a power amplification unit. The high-permeability transformer unit comprises a first magnetic core, a second magnetic core, a first magnet exciting coil, a second magnet exciting coil, a third magnetic core, a primary coil, a secondary coil and an auxiliary coil, wherein the first magnetic core and the second magnetic core are independent of each other; the first magnet exciting coil and the second magnet exciting coil are wound around the first magnetic core and the second magnetic core respectively; the third magnetic core, the first magnetic core and the second magnetic core are overlapped so as to form an integrated magnetic core; the primary coil, the secondary coil and the auxiliary coil are wound around the integrated magnetic core. The performance of the alternating current/direct current sensor is improved remarkably. The alternating current/direct current sensor has the advantages of being low in power dissipation, high in magnetic disturbance resistance capacity, simple in structure, light, high in response speed, high in flexibility, good in interchangeability, convenient to install, calibrate, adjust and maintain, and the like.

The present invention discloses a modeling method for a magneto-rheological damper inverse model and application thereof. The modeling method is characterized by deriving a mathematical expression of the magneto-rheological damper inverse model on the basis of a transformation model of a Bouc-Wen model, and establishing a correspondence relationship among an excitation current of a magneto-rheological damper, a controllable damping force, a relative offset of the damper and a relative speed of the damper. A control circuit of the magneto-rheological damper inverse model comprises an implementation circuit of the magneto-rheological damper inverse model, a magneto-rheological damper driving circuit and the magneto-rheological damper, which cooperatively constitute a closed-loop control system of the magneto-rheological damper. According to the modeling method for the magneto-rheological damper inverse model and the application thereof, which are disclosed by the present invention, the modeling process of the magneto-rheological damper inverse model can be simplified, and an error of the damping force of the magneto-rheological damper, which is caused by an inherent non-linear hysteresis characteristic, is reduced, so that control precision of the damping force is improved.

The invention relates to a giant magnetoresistance current sensor and relates to a device for measuring currents. The giant magnetoresistance current sensor is composed of an electromagnetic conversion module, a signal amplification module and a feedback compensation module, wherein the electromagnetic conversion module comprises a magnetic core of a magnetism accumulation ring, a primary winding and a giant magnetoresistance chip, the signal amplification module comprises an operational amplifier and a push-pull power amplifier, and the feedback compensation module is a feedback winding. The whole measurement circuit forms a closed loop system, and the giant magnetoresistance chip and the magnetic core of the magnetism accumulation ring form a closed structure. The giant magnetoresistance current sensor overcomes the defects that a giant magnetoresistance current sensor in the prior art is very prone to interference of an external stray magnetic field, temperature drift and zero drift cannot be eliminated completely, and the measurement accuracy is affected by intrinsic magnetic hysteresis existing in a magnetic device.

The present invention is cylinder induction type self sensing method and system for MR damper. One induction coil is wound onto the cylinder of single-cylinder piston type MR damper and excited with the harmonic magnetic field of the exciting coil wound on the piston head of the MR damper to output information of relative displacement state between the piston rod and the cylinder, and this constitute the basic structure of cylinder induction type integrated relative displacement sensor. One active magnetoelectric relative displacement sensor is integrated to the MR damper structure to realize the real-time detection of relative displacement information between the controlled target and the supporting body. The continuous damping force controlling characteristic of magnetic reological fluid damper is combined to make the semi-active damping system of MR damper possess continuously controllable self sensing and damping force.

The invention discloses a Vernier type TDC circuit based on an FPGA carry chain. The Vernier type TDC circuit comprises a coarse counting unit, a single-step Vernier fine counting unit, a clock extracting unit and a timestamp combining unit: the coarse counting unit is used for generating a coarse counting part in a timestamp result; the single-step Vernier fine counting unit is used for generating a fine counting part in the timestamp result, a slow delay line in the single-step Vernier fine counting unit is of a loop structure in which two equivalent basic delay units are included, and a quick delay line of the single-step Vernier fine counting unit is of a loop structure in which only one equivalent basic delay unit is included; the clock extracting unit is used for finding and searching for a coarse clock signal which occurs after a detected signal and the nearest to the detected signal; the timestamp combining unit is used for combining and outputting a complete timestamp result.The Vernier type TDC circuit solves the problem in he prior art that since a large quantity of delay units which are nonuniform in width distribution are utilized, the nonlinear error is large, and the measurement precision of a TDC is obviously improved.

The invention provides a dual-frequency laser interferometer, which comprises a first polarization splitting prism, a second polarization splitting prism, a compensating mirror and a first cube-corner prism which are arranged in the reflected light direction of the first polarization splitting prism, a quarter wave plate and a reflector which are arranged in the transmitted light direction of the first polarization splitting prism, and a second cube-corner prism which is opposite to the second polarization splitting prism and arranged at the other side of the first polarization splitting prism; wherein the thickness of the compensating mirror is 2 times of that of the quarter wave plate. On one hand, the dual-frequency laser interferometer with high stability can increase the extinction ratio of the reflected light and reduce the nonlinear error in the premise of not increasing the processing difficulty of the polarization splitting prism; and on the other hand, the dual-frequency laser interferometer reduces the heat drift error to the maximum; therefore, the dual-frequency laser interferometer has the advantages of low heat drift error, low nonlinear error, simple assembling and adjusting, easy component processing and the like.

The invention discloses an anti-polarization mixing single-path circular polarization interference and single wollaston prism splitting-type homodyne laser vibrometer, which belongs to the field of laser interference measurement. According to an interference part, circular polarization reference lights and circular polarization measurement lights with orthogonal single-path polarization directions and coincident light paths are generated through two quarter wave plates and a non-polarization beam splitter (NBS); according to a detection part, after the reference lights and the measurement lights are split, four paths of photoelectric signals with a phase difference of 90 DEG are generated via the same wollaston prism, and outstanding characteristics for suppressing nonlinear errors can be acquired in aspects of the light path structure and the principle. Four-channel homodyne orthogonal laser interference measurement can be realized, problems that polarization leakage and polarization mixing exist in the light path in the prior technical scheme, an output signal has DC bias errors and non-orthogonal errors, the measurement result has a significant nonlinear error and the like can be effectively solved, and significant technical advantages are provided in the field of ultra precision vibration measurement.

The present invention provides a switch-body PMOS switch with switch-body dummies, concretely a sample-and-hold feed switch having parallel branches, each extending from an input node to an output node connected to a hold capacitor. Each branch has a PMOS switch FET connected to a matching PMOS dummy FET. A sample clock switches the PMOS switch FETs on and off, and a synchronous inverse sample clock effects complementary on-off switching of the PMOS dummy FETs. Concurrently, a synchronous inverse sample clock switches the NMOS switch FETs on and off, and the sample clock effects a complementary on-off switching of the NMOS dummy FETs. A bias sequencer circuit biases the bodies of the PMOS switch FETs and the bodies of the PMOS dummy FETs, in a complementary manner, and biases the NMOS switch FETs and the NMOS dummy FETs, also in a complementary manner. The on-off switching of the PMOS dummy FETs injects charge, cancelling a charge injection by the PMOS signal switch FETs, and injects glitches cancelling glitches injected by the PMOS signal switch FETs. The on-off switching of the NMOS dummy FETs injects charge that cancels a charge injection by the NMOS signal switch FETs, and injects glitches that cancels glitches injected by the NMOS signal switch FETs.

The invention discloses a real-time integrator drifting compensation alternation-type integrator and an error control method of the real-time integrator drifting compensation alternation-type integrator. The integrator comprises real-time compensation-type integral units, a field-programmable gate array (FPGA) module, switch modules, an analog-digital converter (ADC) module and a digital-analog converter (DAC) module. Real-time integrator drifting compensation-type integrator bodies are adopted for the real-time compensation-type integral units, two-way single-pole double-throw switches are adopted for the switch modules, the two real-time compensation-type integral units carry out alternate integration on differential signals at different time periods, signals output by the integral units are converted into digital signals through the ADC, the digital signals are kept and accumulated in the FGPA, the integral signal splicing is completed, and finally the integral signals are converted into analog signals through the DAC for being output. According to the real-time integrator drifting compensation-type alternation-type integrator, the problems that for an analog integrator, a zero drift, capacitance leakage errors, non-linear errors and operational amplifier saturation exist can be solved.

The invention provides an AC servo motor based on a position feedback structure. According to the AC servo motor based on the position feedback structure, a motor shaft is directly connected with the screw of a machine table workbench to drive the screw of the machine tool workbench to move; a speed and position detecting device is coaxially connected with the AC servo motor and composed of a speed detector and a position detector, wherein the position detector can directly detect the angular displacement of rotation of the motor shaft of the AC servo motor; the detecting signals of the speed detector is fed back to a speed servo mechanism through a speed feedback device; the detecting signals of the position detector are fed back to a position adjusting mechanism. The AC servo motor based on the position feedback structure also comprises an error detecting device, which is used for detecting the practical displacement of the machine tool workbench and sending the detecting signals to an error compensating device connected with a memory and a numerical control machine tool; error compensation values are prestored inside the memory; the numerical control machine tool corrects control instructions according to the practical displacement and the error compensation values to reduce actual position errors.

The invention provides an anti-polarization-aliasing Michelson heterodyne laser vibration measuring instrument based on single acousto-optic modulation and non-polarization beamsplitting, and belongs to the field of laser interferometry. A non-polarization beamsplitter NBS is used to split beams to form a reference arm and a measuring arm. Through an acoustic optical modulator, diffraction occurs to the incident beam on the reference arm, frequency-shift first-order diffraction light is adjusted through a light beam reflex component, so propagation direction of the light beam is parallel to the direction of the incident beam. Through adjusting a reference cube-corner prism, reflected light is above the acoustic optical modulator, so that the reference light just passes through the acoustic optical modulator for one time. A measuring cube-corner prism is adjusted, so that when the reference light and the measuring light pass through the non-polarization beamsplitter NBS again, light beams are overlapped, and interference occurs. The instrument uses relatively few optical elements to realize heterodyne laser interference measurement, optical path adjustment is simple, and the instrument effectively solves problems in existing technical schemes of polarization leakage and polarization aliasing, and complex optical path adjustment. The instrument has substantial technical advantages in the field of ultra-precision vibration measurement.

The invention discloses a differential single-frequency interference signal processing device and method with an integrated four-quadrant photoelectric detector. The processing device comprises an interference unit and detection unit; and a photoelectric phase modulator is added to a reference arm. The detection unit consists of a quarter-wave plate, a polarizer piece, a beam expander and an integrated four-quadrant photoelectric detector and is used for detecting interferometric fringes of a measuring beam and a reference beam and generating four paths of interference signals. The photoelectric phase modulator applies a high-frequency sine wave modulation voltage, so that the interference signal becomes a phase generation carrier interference signal including to-be-tested phase information. PGC demodulation is carried out to obtain four groups of orthogonal signals; calculation is carried out to obtain four paths of interference signal phases; and a differential phase change is calculated to measure the displacement, a deflection angle and a pitch angle and compensation is carried out. According to the invention, the non-linear error of the measuring method is reduced; the light intensity interference influence caused by poor performances of an optical element or a mounting error is eliminated; the phase measurement accuracy and stability are improved; the angle measurement precision and the measuring range are increased; and the measurement accuracy of the displacement is improved.

The invention discloses an in-situ measurement planning method for a high-steepness complex curved surface and belongs to the field of curved surface measurement. According to the method, the non-equidistant transverse section contour lines of a complex curved surface are generated with equiluminous angles adopted as constraint conditions; a full-surface latticed scanning measurement path is obtained based on the longitudinal section contour lines and non-equidistant transverse section contour lines of the complex curved surface; the concave-convex characteristics of the surface are extractedaccording to average curvature changes in two parameter directions, and local encryption scanning contour lines are generated; multi-section splicing measurement motion planning is carried out according to the equiluminous angles and the obtained scanning path, so that the movement trajectory of the reference point of a sensor is obtained; and finally, the measurement deflection angle of an optical measuring head is detected, so that the in-situ measurement planning of the complex curved surface is completed. With the method adopted, the in-place scanning path generation and measurement motionplanning of the high-steepness complex curved surface are achieved; the measurement precision of a characteristic area is guaranteed; and dynamic measurement errors caused by the multi-axis linkage of a machine tool are reduced. The method is reliable and high in universality.

The invention discloses a non-linear self-correction structured light three-dimensional measurement method and system for sine fringes, and relates to the technical field of optical three-dimensional measurement. A new mathematical model of a direct-current component is provided according to system nonlinear response, respective modulation intensity and mean value intensity of three groups of sine fringes are adjusted based on the model of the direct-current component, an equation about nonlinear response is established, respective nonlinear corresponding parameters of each pixel are obtained through calculation, the gray level of the fringe image is corrected through the inverse function of the nonlinear response equation, the wrapping phase and the unwrapping phase of the corrected fringe image are calculated, finally, a three-dimensional point cloud is reconstructed according to triangulation ranging, a three-dimensional model of the object to be measured is built, and three-dimensional measurement of the object to be measured is completed. Projection time and huge matrix inversion calculation time consumption do not need to be increased, nonlinear errors of different frequency phases are reduced, therefore, the phase wrapping precision and the unwrapping precision can be improved at the same time, and high-speed and high-precision three-dimensional measurement is achieved.

Provided is a circuit which comprises a pipeline analog/digital converter which converts an analog input signal to a digital output signal and a feedback circuit coupled with the converter, therefore, the digital output signal is adapted to have an average non linearity error value of about zero volt.

A polarization- and aliasing-resistance Michelson heterodyne laser vibration measurer based on double acousto-optic modulation and non-polarizing light splitting belongs to the field of laser interference measurement. A non-polarizing beam splitter (NBS) is adopted to perform light splitting and then form a reference arm and a measuring arm, incident light beams on the reference arm and the measuring arm generate diffraction via acousto-optic modulators, and frequency-shifted first-stage diffraction light are adjusted through light beam folding elements, so light beam propagation directions are parallel to the incident light beams; reflected light is located over acousto-optic modulators through adjustments of cube-corner prisms, so measuring light and reference light respectively pass through the acousto-optic modulators for one time; and the reference cube-corner prism and the measuring cube-corner prism are adjusted, so light beam superposition occurs when the reference light and the measuring light pass through the non-polarizing beam splitter (NBS) again, and an interference is generated. Heterodyne laser measuring is achieved through adoption of less optical elements, optical path adjustments are simple, problems of polarization leakage, polarization aliasing, complex optical path adjustments and the like which exist in an existing technical scheme can be effectively solved, and the laser vibration measurer has an obvious technical advantage in the ultra-precision vibration measurement field.

A special test circuit system for electronic accelerator pedals comprises a force sensor, an angle sensor, a signal preprocessing unit, an A/D conversion unit, a micro controller unit, a photoelectric limit switch, an RS-232 interface, a direct-current gear motor driver, a power unit, and a PC. The test circuit system has the advantages of simple circuit structure, low design and manufacture costs, high detection precision, visual and easy-to-save test results, and high degree of test process automation. The workload of accelerator pedal detection on workers can be reduced greatly, and the production efficiency and product quality can be improved. The special test circuit system for electronic accelerator pedals is of vital significance to the optimization of product quality and the improvement of market competitiveness of products.