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2422 results about "System error" patented technology

Inertial GPS navigation system with modified kalman filter

An inertial (“INS”)/GPS receiver includes an INS sub-system which incorporates, into a modified Kalman filter, GPS observables and/or other observables that span previous and current times. The INS filter utilizes the observables to update position information relating to both the current and the previous times, and to propagate the current position, velocity and attitude related information. The GPS observable may be delta phase measurements, and the other observables may be, for example, wheel pick-offs (or counts of wheel revolutions) that are used to calculate along track differences, and so forth. The inclusion of the measurements in the filter together with the current and the previous position related information essentially eliminates the effect of system dynamics from the system model. A position difference can thus be formed that is directly observable by the phase difference or along track difference measured between the previous and current time epochs. Further, the delta phase measurements can be incorporated in the INS filter without having to maintain GPS carrier ambiguity states. The INS sub-system and the GPS sub-system share GPS and INS position and covariance information. The receiver time tags the INS and any other non-GPS measurement data with GPS time, and then uses the INS and GPS filters to produce INS and GPS position information that is synchronized in time. The GPS/INS receiver utilizes GPS position and associated covariance information and the GPS and/or other observables in the updating of the INS filter. The INS filter, in turn, provides updated system error information that is used to propagate inertial current position, velocity and attitude information. Further, the receiver utilizes the inertial position, velocity and covariance information in the GPS filters to speed up GPS satellite signal re-acquisition and associated ambiguity resolution operations
Owner:NOVATEL INC

Operation positioning device and method and robot operation system

ActiveCN104083217AEasy to get placementAvoid restrictionsDiagnosticsSurgeryX-rayEngineering
The invention relates to an operation positioning device and method and a robot operation system. The operation positioning device comprises a positioning ruler, an upper computer and a series-connection mechanical arm with at least six degrees of freedom. The upper computer is connected with the series-connection mechanical arm, the positioning ruler comprises two opposite surfaces allowing X-rays to transmit, the two opposite surfaces are fixedly connected through a connecting surface allowing X-rays to transmit, the two opposite surfaces are respectively provided with a group of marks, each group of marks comprise at least four mark points which are not located on the same straight line, and the mark points are X-ray-proof components. Any opposite surface or the connecting surface is fixedly connected with a ruler handle, and the ruler handle is connected with the tail end of the series-connection mechanical arm through a port. The upper computer adjusts the position of the positioning ruler by controlling movement of the series-connection mechanical arm, space positioning calculation is conducted according to the mark points in collected images, and a planning path is obtained. The device can achieve perspective positioning at any angle, and can eliminate system errors caused when an operation path is calculated, increase working space and improve the operation positioning accuracy.
Owner:BEIJING TINAVI MEDICAL TECH

Non-cooperative spacecraft attitude estimation method based on virtual sliding mode control

The invention discloses a non-cooperative spacecraft attitude estimation method based on virtual sliding mode control, and belongs to the technical field of non-cooperative spacecraft navigation. The non-cooperative spacecraft attitude estimation method comprises the following steps: utilizing a virtual control sliding mode controller based on the Lyapunov principle; using target satellite absolute attitude obtained by a stereoscopic vision system as a control objective; according to motion characteristics of the target satellite, establishing a virtual satellite motion model of the target satellite; using a kinetic model of the virtual satellite as a controlled member to obtain attitude parameters of the virtual satellite; using attitude parameters estimated by the virtual satellite and the target satellite absolute attitude obtained by the stereoscopic vision system as controlled input, and calculating the virtual revolving moment on the motion model of the virtual satellite through the virtual sliding mode controller, so as to realize the estimation of the target satellite attitude parameters by the virtual control sliding mode controller. The non-cooperative spacecraft attitude estimation method disclosed by the invention is low in calculated amount, and can still achieve higher convergence rate and higher precision when the initial error of the state variables is high or the system error emerges, so as to meet the requirements of the high performance navigation system.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS

Improved active-disturbance-rejection position controller for direct current (DC) motor, and design method of improved active-disturbance-rejection position controller

The invention discloses a structure and a design method of an improved active-disturbance-rejection position controller for a direct current (DC) motor; the DC motor is taken as a controlled object, and an output position signal is taken as a controlled variable; the controller mainly consists of four parts, i.e., a tracking differentiator, a nonlinear state error feedback part, an extended state observer and a disturbance compensation part. The improved active-disturbance-rejection position controller is mainly used to improve a fal function in a nonlinear function in the extended state observer, and the fal function is used to determine the tracking performance of the extended state observer and the controller; the concrete improvement measure is adding a linear feedback area into non-linear feedback; therefore, the problem that in the traditional method, timely control cannot be realized when the system error is too large and the gain is too low can be solved on the basis of guaranteeing system stability. By comparing simulation lines obtained before and after the improvement for the controller, the structure and the design method which are provided by the invention are proved to accelerate the output signal response speed under the condition that the position error of the DC motor is larger, thus improving the integral control performance of a system.
Owner:NANJING UNIV OF POSTS & TELECOMM

Sequential approximation analog to digital converter with digital correction and processing method thereof

The invention discloses a sequential approximation analog to digital converter with digital correction and a processing method thereof aiming at the defect of difficult composition manufacture of a coupling capacitor in the traditional sequential approximation analog to digital converter. The sequential approximation analog to digital converter comprises a main DAC (Digital Analogue Converter), acalibration DAC, a comparer, a control circuit and a storage. The sequential approximation analog to digital converter is characterized in that the main DAC comprises a high-K-bit CDAC (Capacitance Digital Analogue Converter) and a low-N-bit CDAC. Introduced system errors and capacitance matching errors are digitally corrected and eliminated, error voltages corresponding to capacitors in the high-K-bit CDAC are quantized and stored in the storage, and two-digit 0 are added behind the tail of the quantized residual error voltage digital code and participate in the calculation of the error voltages. When normal conversion is carried out, the error voltage digital codes are accumulated and then last two digits are discarded, the remain digital codes are used as the input of the calibration DAC, thus the accuracy of the analog to digital converter is improved.
Owner:UNIV OF ELECTRONICS SCI & TECH OF CHINA

Quad-rotor unmanned aerial vehicle (UAV) fault tolerance control method based on adaptive fault estimation observer

The invention discloses a quad-rotor UAV fault tolerance control method based on an adaptive fault estimation observer, and belongs to the field of aviation aircraft control. The method comprises thata fault model of a quad-rotor attitude system is established according to a dynamic model of a quad-rotor UAV by considering a performer fault of a UAV system; a performer of the UAV includes four rotor motors in practicality, faults correspond to the four rotor motors, the fault model is processed, the faults are divided into two groups decoupled mutually, and a final attitude fault model is obtained; according to the provided fault model, the adaptive fault estimation observer is designed, corresponding adaptive laws are provided, the performance fault is estimated, and an H(infinite) method and an interval matrix method are used on external disturbance and parameter nondeterminacy respectively in the design process; and an attitude system error fault model is obtained on the basis of the fault model, a dynamic output feedback fault tolerance controller is designed on the basis of a fault estimated value, and fault tolerance control of the quad-rotor UAV is realized. Influence of the performer fault on performance of the quad-rotor UAV can overcome, and the safety and reliability of the UAV in the flight process are ensured fully.
Owner:CENT SOUTH UNIV

Time-domain ground-air electromagnetic detection system and calibration method

The invention relates to a time-domain ground-air electromagnetic detection system and a calibration method, in particular to a system consisting of an induction signal recording device connected with a ground recording device global position system (GPS) synchronization unit, a closed abnormal ring and a data quality evaluation system, and a calibration method for the time-domain ground-air electromagnetic detection system. The closed abnormal ring and the induction signal recording device are adopted, the induction current and induction voltage are simultaneously recorded, and the 24-bit 200Hz sampling rate, a bandwidth of 0-13KHz and a dynamic range of an amplifier of 160dB are achieved. Moreover, the system is synchronous with a ground transmitter and an air receiver GPS, and during measurement, by removing earth background field data, a pure closed abnormal ring electromagnetic signal containing a geometric error is extracted, is input into the data quality evaluation system, andis compared and fitted with the computed closed abnormal ring theoretical value, the system error, the geometric parameter error and the detection resolution of the time-domain ground-air electromagnetic detection system are determined, and the performance of the electromagnetic detection system is tested and calibrated.
Owner:JILIN UNIV
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