2382 results about "Tracking error" patented technology

Line locator systems that fuse traditional sensors used in a combined pipe and cable locator (electromagnetic coils, magnetometers, and ground penetrating radar antennas) with low cost inertial sensors (accelerometers, gyroscopes) in a model-based approach are presented. Such systems can utilize inexpensive MEMS sensors for inertial navigation. A pseudo-inertial frame is defined that uses the centerline of the tracked utility, or an aboveground fixed object as the navigational reference. An inertial sensor correction mechanism that limits the tracking errors over time when the model is implemented in state-space form using, for example, the Extended Kalman Filter (EKF) is disclosed.

A laser produced plasma (“LPP”) extreme ultraviolet (“EUV”) light source control system comprises a target delivery system adapted to deliver moving plasma initiation targets and an EUV light collection optic having a focus defining a desired plasma initiation site, a target tracking and feedback system comprising: at least one imaging device providing as an output an image of a target stream track, and a stream track error detector detecting an error in the position of the target stream track in at least one axis generally perpendicular to the target stream track from a desired stream track intersecting the desired plasma initiation site.

A method for steering an agricultural vehicle comprising: receiving global positioning system (GPS) data including position and velocity information corresponding to at least one of a position, velocity, and course of the vehicle; receiving a yaw rate signal; and computing a compensated heading, the compensated heading comprising a blend of the yaw rate signal with heading information based on the GPS data. For each desired swath comprising a plurality of desired positions and desired headings, the method also comprises: computing an actual track and a cross track error from the desired swath based on the compensated heading and the position; calculating a desired radius of curvature to arrive at the desired track with a desired heading; and generating a steering command based on the desired radius of curvature to a steering mechanism, the steering mechanism configured to direct the vehicle.

A method for steering an agricultural vehicle comprising: receiving global positioning system (GPS) data including position and velocity information corresponding to at least one of a position, velocity, and course of the vehicle; receiving a yaw rate signal; and computing a compensated heading, the compensated heading comprising a blend of the yaw rate signal with heading information based on the GPS data. For each desired swath comprising a plurality of desired positions and desired headings, the method also comprises: computing an actual track and a cross track error from the desired swath based on the compensated heading and the position; calculating a desired radius of curvature to arrive at the desired track with a desired heading; and generating a steering command based on the desired radius of curvature to a steering mechanism, the steering mechanism configured to direct the vehicle.

Line locator systems that fuse traditional sensors used in a combined pipe and cable locator (electromagnetic coils, magnetometers, and ground penetrating radar antennas) with low cost inertial sensors (accelerometers, gyroscopes) in a model-based approach are presented. Such systems can utilize inexpensive MEMS sensors for inertial navigation. A pseudo-inertial frame is defined that uses the centerline of the tracked utility, or an aboveground fixed object as the navigational reference. An inertial sensor correction mechanism that limits the tracking errors over time when the model is implemented in state-space form using, for example, the Extended Kalman Filter (EKF) is disclosed.

The invention discloses a nonlinear output feedback flight control method for a quad-rotor unmanned aerial vehicle. The nonlinear output feedback flight control method for the quad-rotor unmanned aerial vehicle comprises the following steps of: (1) determining a kinematic model of the quad-rotor unmanned aerial vehicle under an inertial coordinate system and a kinematic model of the quad-rotor unmanned aerial vehicle under a body coordinate system; (2) designing an attitude control system of the quad-rotor unmanned aerial vehicle; defining tracking errors of the attitude angle and the angular speed of the quad-rotor unmanned aerial vehicle; designing a filter to perform online estimation on an angular speed signal and obtain an open loop dynamic equation of the tracking errors; and estimating unknown functions in the open loop dynamic equation by adopting neural network feedforward, and designing attitude system control output of the quad-rotor unmanned aerial vehicle; and (3) designing a height control subsystem of the quad-rotor unmanned aerial vehicle; defining height tracking errors and defining auxiliary filtering tracking errors; and designing a height subsystem controller. According to the nonlinear output feedback flight control method for the quad-rotor unmanned aerial vehicle disclosed by the invention, the polarity problem is effectively avoided, a wide-range stable control effect is achieved, the robust performance of the system is greatly improved, and the dependence of a flight controller on an airborne sensor is greatly reduced.

Method and system for analyzing and processing information on one or more aircraft flight paths, using a four-dimensional coordinate system including three Cartesian or equivalent coordinates (x, y, z) and a fourth coordinate δ that corresponds to a distance estimated along a reference flight path to a nearest reference path location corresponding to a present location of the aircraft. Use of the coordinate δ, rather than elapsed time t, avoids coupling of along-track error into aircraft altitude and reduces effects of errors on an aircraft landing site. Along-track, cross-track and / or altitude errors are estimated and compared with a permitted error bounding space surrounding the reference flight path.

The invention relates to a multi-objective coordination-typed self-adaptive cruise control method for a vehicle, comprising the following steps: 1) according to the detail requirements of the multi-objective coordination-typed self-adaptive cruise control for a vehicle, the performance indicators and I / O restriction of MTC ACC are designed, and multi-objective optimization control problem is established; and 2) MTC ACC control law rolling time domain is used for solving the objective optimal control problem, and the optimal open-loop control quantity is used for carrying out feedback and achieving closed-loop control. Based on the steps, the control method comprises the following four parts of contents: 1. the modeling for the longitudinal dynamics of a traction system; 2. the performance indicators of MTC ACC; 3. the I / O restriction design of MTC ACC; and 4. solution by the MTC ACC control law rolling time domain. By constructing multi-objective optimization problem, the control method not only solves the contradiction among the fuel economy, the track performance and the feeling of the driver, moreover, on the same simulation conditions, compared with the LQ ACC control, the control method simultaneously reduces the fuel consumption and vehicle tracking error of the vehicle, and achieves the multi-objective coordinating control function.

The invention relates to a quadrotor unmanned plane control method based on a fuzzy expansion state observer and an adaptive sliding formwork. The method comprises steps that a quadrotor unmanned plane system model is established, and a system state and controller parameters are initiated; a tracking differentiator is designed; a non-linear expansion state observer is designed; fuzzy rules are established; a parameter adaptive law is designed; an adaptive sliding formwork controller is designed. According to the method, the expansion state observer is designed to estimate indetermination of a system model and external disturbance; a pole assignment method is utilized to determine an initial value of an expansion state observer parameter; the fuzzy rules are introduced to realize online setting for the expansion state observer parameter; the parameter adaptive law is designed to acquire ideal controller gain; the adaptive sliding formwork controller is designed, rapid stabilization of a system tracking error and convergence to a zero point are guaranteed, and rapid and stable position tracking and pose adjustment of the quadrotor unmanned plane are realized. The method is advantaged in that system performance is improved, and rapid and stable system position tracking and pose adjustment are realized.

The invention discloses a heliostat tracking error correction method. Based on the characteristics that a heliostat tracking deviation angle has small variation in a short time and the tracking deviation angles at the same moment in the adjacent days have small variation, an image collecting and processing system is adopted to detect and obtain the tracking deviation angles of a certain heliostat at multiple moments in the whole day, or the tracking deviation angles obtained by the heliostat at multiple moments in one day or previous days are taken as the intraday tracking deviation angle; an intraday tracking deviation curve of the heliostat is obtained by the interpolation; according to the tracking deviation curve, the current angle of the heliostat is corrected to ensure that the facula of the heliostat can basically accurately be projected to a target position. The invention obtains the tracking deviation angles at multiple moments by detection of heliostat tracking error many days a year or many times a day; the everyday corresponding tracking deviation curve of each heliostat can be found by one-year or multiple-year tracking deviation angle data analysis treatment and curve fitting; and thus, the facula of the heliostat can be projected to the target position more accurately.

A method for steering an agricultural vehicle comprising: receiving global positioning system (GPS) data including position and velocity information corresponding to at least one of a position, velocity, and course of the vehicle; receiving a yaw rate signal; and computing a compensated heading, the compensated heading comprising a blend of the yaw rate signal with heading information based on the GPS data. For each desired swath comprising a plurality of desired positions and desired headings, the method also comprises: computing an actual track and a cross track error from the desired swath based on the compensated heading and the position; calculating a desired radius of curvature to arrive at the desired track with a desired heading; and generating a steering command based on the desired radius of curvature to a steering mechanism, the steering mechanism configured to direct the vehicle.

An information recording apparatus is provided, which can control over the power of light beams emitted from a light source and various types of servo control with higher accuracy. A laser beam is emitted from a semiconductor laser to write information onto an optical disc. A detection signal indicative of the power of the laser beam output from a light-receiving device is sampled and held with a sample and hold circuit via an I-V converter at a timing delayed by the time corresponding to the delay time of the I-V converter. A tracking error generation circuit and a focus error generation circuit generate a tracking error signal and a focus error signal, respectively, on the basis of a detection signal having information about tracking error and focus error and output from a light-receiving device. Sample and hold circuits sample and hold the tracking error signal and the focus error signal at a timing delayed by the time corresponding to the delay time of each of the generation circuits, respectively. Power control, tracking servo, and focus servo are performed using each of the signals held by the sample and hold circuits, respectively.

The invention discloses a pilotless automobile lateral control method based on turning curvature estimation. The pilotless automobile lateral control method based on the turning curvature estimation comprises setup of a preconceived track, collection of GPS-INS integrated positioning system data and steering wheel turning angle command signals send out by an autopilot, and especially is a method that a preview distance based on a road curvature is set firstly, and then a preview point A and a preview point B are reset according to the preview distance, later, longitudes and latitudes of the preview point A and the preview point B are converted into a vehicle coordinate system to work out an optimum turning curvature, and steering wheel turning angle controlled quantity is worked out according to the optimum turning curvature and is output to the autopilot to achieve lateral control of a pilotless automobile. According to the pilotless automobile lateral control method based on the turning curvature estimation, through actual measurement, the maximum tracking error is only 0.4m when the speed of the automobile is at 20km / h, the maximum tracking error is only 0.6m when the speed of direction change is 5km / h; both accurate tracking of various kinds of complex tracks is achieved, and steering wheel shaking caused by single-point preview feedback control is avoided, and the control quantity of the pilotless automobile is more smooth; the method can be widely used in pilotless driving control of the various kinds of vehicles.

A multi-band receiver in which characteristics including a tracking error are improved is provided with a variable frequency oscillator circuit, a variable divider circuit (39) for dividing an oscillation signal (SVCO) of the variable frequency oscillator circuit, and mixer circuits (15I) and (15Q) for subjecting a received signal SRX to frequency conversion into an intermediate frequency signal (SIF) by a local oscillation signal (SLO). A divided output of the variable divider circuit (39) is supplied as the local oscillation signal (SLO) to each of the mixer circuits (15I) and (15Q). When a signal in a first frequency band is received, the division ratio n of the variable divider circuit (39) and the oscillation frequency of the variable frequency oscillator are changed to change the reception frequency in the first frequency band. When a signal in a second frequency band is received, at least the oscillation frequency of the variable frequency oscillator circuit is changed to change the reception frequency in the second frequency band.

The invention discloses an unmanned surface vessel formation control method based on a leader follow-up structure. The method is used for multiple fully-driven unmanned surface vessel systems, and a formation control method based on a leader-follower is provided to prevent any follower from colliding and being kept in connection with a leader thereof. The method comprises following steps of establishing a dynamic model of an unmanned surface vessel; setting a position output tracking error constraint condition of a follower; designing a tracking error conversion function; applying the dynamic surface control technology and designing a virtual controller; designing a disturbance observer for compensating external unknown interference like wind wave flows; and constructively designing a tracking formation controller. According to the invention, it is ensured that any follower is always kept away from the leader thereof for a certain safe distance, and is in a communication connection range of the leader thereof; and by use of the dynamic surface control technology, accelerated speed of the leader is prevented from being used and practicability of a design scheme is improved.

An optical information apparatus of the present invention includes: an optical pick-up head including: a light source; a diffraction unit; a condensing unit; a beam splitter; a photodetector; and a tracking error signal generator. An optical recording medium has tracks arranged substantially at a constant pitch. An average of a pitch is tp. When a main beam is placed on the track, a first sub-beam and a second sub-beam are placed between the tracks. The tracking error signal generator performs a differential arithmetic operation with respect to signals output from a light-receiving portion receiving the main beam to generate a first push-pull signal, performs a differential arithmetic operation with respect to signals output from the light-receiving portions receiving the first sub-beam and the second sub-beam to generate a second push-pull signal, and performs a differential arithmetic operation with respect to the first push-pull signal and the second push-pull signal to generate a tracking error signal, in a case where an amplitude of the first push-pull signal obtained at the pitch tp is fluctuated when the light beam is scanned in a direction orthogonal to the tracks of the optical recording medium.

The invention provides rehabilitation training system and method combined with functional electric stimulation and a robot. The system comprises a functional electric stimulation part, a robot part and a control unit which is respectively connected with the functional electric stimulation part and the robot part, wherein the control unit is used for receiving bioelectric signals and controlling the functional electric stimulation part and the robot part at real time according to the mode of adjustable auxiliary proportion of the functional electric stimulation part and the robot part or the mode of adjustable tracking error so that the functional electric stimulation part can stimulate the corresponding muscle groups of a joint of a patient and the robot part can provide a joint auxiliary torque for the patient. The invention can be applied to progressive interactive rehabilitation of elbow joints, wrist joints, knee joints, ankle joints and shoulder joints and can help patients carry out active rehabilitation training in an improved movement space, thereby greatly accelerating the recovery of movement function of joints of affected sides.

The invention relates to a flexible satellite locus linearization attitude control method based on a disturbance observer. The invention aims at solving problems that a single locus linearization control method is poor in capability of inhibiting interference, is poorer in robustness, and does not consider external interference and the impact from flexible accessories. The method comprises the steps: employing Euler angles for describing attitudes of a spacecraft, employing an idea of equivalent disturbance, and building a flexible spacecraft dynamics and kinetics equation; solving the pseudo-inverse of a controlled object under the condition of neglecting equivalent disturbance, designing a quasi-differentiator of a specific type, and obtaining the nominal control of an expected locus; and designing a linear time varying adjuster through proportion-integration control. The method gives consideration to the influence of equivalent disturbance, designs the disturbance observer, and guarantees the asymptotic convergence of a tracking error of a flexible spacecraft. The method improves the anti-interference capability of a system, and improves the robustness of the system. The method is used in the attitude control field of flexible satellites.

A method and device for tracking error propagation and refreshing a video stream is provided. The proposed subject matter comprises of an error propagation tracking method that works in the sub-sampled domain to reduce computational cycles and memory bandwidth. Further, the tracking based update of the error propagation metric is done differently for static and non-static regions to avoid unnecessary refresh of static areas. Through suitable thresholding of the metric at a macroblock (MB) level, a set of refresh MBs are selected for each frame. These refresh MBs are coded either as an intra MB or as an inter MB that is predicted from one or more reliable reference frames (—frames that are known to be available at the decoder with negligible errors—). Such inter coding of refresh MBs improves the compression efficiency when compared to pure intra coding of refresh MBs. Further, variants to the threshold selection are presented that result in temporally uniform distribution of the number of refresh MBs and a strict refresh scheme wherein all MBs are guaranteed to be with negligible errors following a packet loss within a committed refresh period. In addition, to using the error propagation metric, spatial connectivity to already chosen refresh MBs is used in the selection of additional refresh MBs within a frame and across frames; this reduces the rate of error propagation due to part of a macroblock predicting from older, erroneous neighboring MBs and in turn requiring more refresh MBs on the average per frame.

The invention relates to a method for controlling a rigid spacecraft for target attitude tracking, and belongs to the technical field of the high-precision and high-stability attitude tracking control of spacecrafts. The method solves the problem that when the attitude tracking spacecraft runs in a low orbit in outer space, the conventional control method cannot eliminate the inherent flutter of a sliding mode variable structure. The method comprises the following steps: 1, establishing a kinetic model and a kinematic model of the rigid spacecraft; 2, setting an attitude tracking error and anexpected attitude parameter of the rigid spacecraft, and combining the attitude tracking error and the expectation attitude parameter with the kinetic model and the kinematic model to establish a mathematical model for the attitude tracking; 3, adopting a control algorithm of a sliding mode variable structure controller to adjust a control law of the mathematical model which is established in thestep 2 and is used for the attitude tracking, and simultaneously combining an observation result of a disturbance observer to modify the control law; and 4, controlling the rigid spacecraft by using the modified control law obtained in the step 3 to realize the attitude tracking. The method is suitable for the attitude tracking of targets running in the outer space.

A robotic system for flexible needle steering under ultrasound imaging. A robot is used to steer the needle along a predetermined curved trajectory by maneuvering the needle base. The needle tip position is detected by an ultrasound sensor and the tracking error of the needle tip from a predetermined needle path is input to a controller which solves the inverse kinematic based on the needle position, and the needle and tissue properties. The control algorithm uses a novel method to detect the elastic properties of the tissue by analyzing tissue motion at the region in front of the needle tip. The inverse kinematic solution may be performed on a model of the needle as a flexible beam having laterally connected virtual springs to simulate lateral forces exerted by the tissue elasticity. The system is able to direct the needle to a target within the tissue while circumventing forbidden regions.

The invention discloses a direct torque control system of a permanent magnet synchronous motor based on a terminal sliding mode, which belongs to the field of motor control. The system comprises a main circuit, a signal detection circuit, a rotational-speed outer-ring controller for the terminal sliding mode, a torque linkage inner-ring controller for an adaptive fuzzy sliding mode, a stator-linkage electromagnetic torque estimation module, an SVPWM module, a 3 / 2 coordinate transform module, and a rotor position / speed estimation module; the design on the rotational-speed outer-ring controller is realized by using a terminal sliding mode control method based on the adaptive estimation of load disturbance, and the rotational-speed outer-ring controller outputs direct-torque controlled demand signals; and the design on the torque linkage inner-ring controller is realized by using an adaptive fuzzy sliding mode control method, and the torque linkage inner-ring controller outputs two-phase alternating voltages in a two-phase stationary coordinate system; and through carrying out SVPWM transformation on the two-phase alternating voltages, a power switching element acted on an inverter of the main circuit implements the direct torque control of the permanent magnet synchronous motor. The direct torque control system in the invention has the advantages of quick torque response speed, good robustness, small tracking error, and capability of improving the reliability and static / dynamic characteristics of the system.

The invention discloses an SINS / GPS super-compact integrated navigation system and an implementing method thereof. The method comprises the following steps: the doppler frequency assistance is provided for a GPS carrier loop by using the velocity information of a strapdown inertial navigation system, therefore, the loop equivalent bandwidth is increased, the influence of the carrier dynamic stateon the carrier loop is lowered, and the noise suppression capability is improved by reducing the bandwidth of a filter; meanwhile, in order to eliminate the correlation between the pseudo-range rate error and the inertial navigation error, a carrier loop tracking error model is obtained by establishing the relationship between the carrier tracking error and the inertial navigation speed error, andthe influence of the carrier tracking error is subduced in the measurement equation; and in addition, the carrier frequency is adjusted according to the output error estimation information, and the tracking accuracy of the carrier loop is enhanced. The invention can effectively enhance the noise suppression capability and the dynamic tracking performance of the tracking loop and enhance the tracking accuracy of a GPS receiver and the navigation accuracy of the integrated navigation system under strong interference and high dynamic circumstance.

A method for steering an agricultural vehicle comprising: receiving global positioning system (GPS) data including position and velocity information corresponding to at least one of a position, velocity, and course of the vehicle; receiving a yaw rate signal; and computing a compensated heading, the compensated heading comprising a blend of the yaw rate signal with heading information based on the GPS data. For each desired swath comprising a plurality of desired positions and desired headings, the method also comprises: computing an actual track and a cross track error from the desired swath based on the compensated heading and the position; calculating a desired radius of curvature to arrive at the desired track with a desired heading; and generating a steering command based on the desired radius of curvature to a steering mechanism, the steering mechanism configured to direct the vehicle.

A six degree-of-freedom trajectory linearization controller (TLC) architecture (30) for a fixed-wing aircraft (46) is set forth. The TLC architecture (30) calculates nominal force and moment commands by dynamic inversion of the nonlinear equations of motion. A linear time-varying (LTV) tracking error regulator provides exponential stability of the tracking error dynamics and robustness to model uncertainty and error. The basic control loop includes a closed-loop, LTV stabilizing controller (12), a pseudo-inverse plant model (14), and a nonlinear plant model(16). Four of the basic control loops (34, 36, 40, 42) are nested to form the TLC architecture (30).

A GNSS receiver tracks the AltBOC (15,10), or composite E5a and E5b, codes using hardware that locally generates the complex composite signal by combining separately generated real and the imaginary components of the complex signal. To track the dataless composite pilot code signals that are on the quadrature channel of the AltBOC signal, the receiver operates PRN code generators that produce replica E5a and E5b PRN codes and square wave generators that generate the real and imaginary components of the upper and lower subcarriers, and combines the signals to produce a locally generated complex composite code. The receiver removes the complex composite code from the received signal by multiplying the received signal, which has been downconverted to baseband I and Q signal components, by the locally generated complex composite code. The receiver then uses the results, which are correlated I and Q prompt signal values, to estimate the center frequency carrier phase angle tracking error. The error signal is used to control a numerically controlled oscillator that operates in a conventional manner, to correct the phase angle of the locally generated center frequency carrier. The receiver also uses early and late versions of the locally generated complex composite pilot code in a DLL, and aligns the locally generated composite pilot code with the received composite pilot code by minimizing the corresponding DLL error signal. Once the receiver is tracking the composite pilot code, the receiver determines its pseudorange and global position in a conventional manner. The receiver also uses a separate set of correlators to align locally generated versions of the in-phase composite PRN codes with the in-phase channel codes in the received signal, and thereafter, recover the data that is modulated thereon.

The invention discloses antenna beam tracking device and method of a moving communication satellite communication system. The antenna beam tracking device comprises a geographical position detection device, a carrier gesture detection unit, a signal intensity detection unit, a signal conditioning circuit and a master control computer, wherein the master control computer controls a servo driver; and the servo driver controls an azimuth and pitching motor. The antenna beam tracking method comprises the following steps of: 1, initially capturing a target satellite; 2, tracking: setting initial parameters, storing and updating the initial parameters in real time, generating simultaneous disturbance random vectors, driving disturbance, measuring the intensity of received signals, estimating gradient, determining tracking error signals, regulating antenna beam pointing directions, and judging the received signals; and 3, recapturing. The invention has the advantages of simple design, low cost, system implementation without changing the hardware structure of an original tracking system, easy operation, high tracking accuracy and fast tracking speed and overcomes the defects of inconvenient operation, complex tracking step, lower tracking accuracy and tracking speed, and the like of the traditional method.

The invention discloses a binary offset carrier signal tracking loop, which comprises a correlator module, a phase discriminator unit and a filter unit. The correlator module is used for performing demodulation and despread processing on the input intermediate frequency BOC signals, and acquiring multi-path correlation values IIP, IIE, IIL, IQP, IQE, IQL and QIP between local signals and the intermediate frequency BOC signals; the phase discriminator unit is used for detecting the tracking error theta of the carrier phase and the subcarrier phase and measuring the tracking error tau of the spreading codes; and the filter unit is used for performing noise reduction and smoothing on the phase demodulation result, converting the output tracking error into corresponding frequency control words, correspondingly feeding the frequency control words back to the correlator module, tracking the input intermediate frequency BOC signals, and closing the tracking loop. The binary offset carrier signal tracking loop realizes the split tracking of the subcarrier and spreading codes, eliminates the tracking fuzziness of the BOC signals, reduces the requirement on the acquisition precision, improves the tracking performance of weak signals, widens the dynamic range of the loop, and improves the tracking stability of the BOC signals by using the periodicity of the subcarrier.