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322results about How to "Prevent inversion" patented technology

Permanent magnet synchronous motor control method and system based on encoder automatic zero set

The invention discloses a permanent magnet synchronous motor control method based on encoder automatic zero set. An improved high-frequency voltage injection method is used for detecting the initial position of a rotor, the initial position of the rotor is clear, voltage vectors can be applied conveniently, and a motor rotor reverse rotating phenomenon is avoided. Meanwhile, encoder zero compensation is carried out automatically, a compensation value is stored, direct calling in the future is convenient, and trouble of manual zero set is removed. Once calibration or zero reset is needed, operation through the method is carried out for one time, an encoder is subjected to accurate zero set again, a process is simple, and accuracy is high. The invention further discloses a control system which achieves the control method. After the initial position of the rotor is obtained through a rotor locating module, a voltage vector closest to the position is chosen to be applied, so that a rotor back-and-forth vibration phenomenon during locating is avoided, a high-frequency voltage signal is injected only before the rotor is located initially, phase lag and time lag cannot be brought to system operation, and noise cannot be introduced during operation.
Owner:ZHEJIANG UNIV

Pointer instrument reading identification method

The invention discloses a pointer instrument reading identification method. The method comprises the steps of extracting a dial plate, removing interference, and correcting the dial plate by using affine transformation; performing circle detection and straight line detection on the dial plate to obtain predicted circle center and pointer angle; based on features of a scale connected domain on thedial plate, screening out the scale connected domain, performing linear fitting on the scale connected domain, calculating an intersection point of every two fitting straight lines, and performing screening verification on a to-be-selected circle center by utilizing the predicted circle center and pointer angle to obtain the circle center of the dial plate, wherein a distance from the centroid ofthe scale connected domain to the circle center on the dial plate is the radius of the dial plate; and according to information such as the circle center of the dial plate, the radius of the dial plate, the straight lines of a pointer, extracting an arc scale bar of the dial plate, expanding the arc scale bar in a rectangular shape, then according to horizontal coordinate distribution of scale onthe rectangular scale bar, performing minimum and maximum scale detection, noisy point removal and scale insertion, and finally in combination with the pointer angle, calculating reading of the dial plate. The method is high in universality and high in timeliness; and the reading has relatively high accuracy.
Owner:HUAZHONG UNIV OF SCI & TECH

Pipe cavity bracket

ActiveCN105496603AAvoid wrinklesAvoid blood blockageStentsBlood vesselsBlood streamCavity wall
The invention discloses a pipe cavity bracket. The pipe cavity bracket comprises a first pipe body and a second pipe body which sleeves the first pipe body, wherein at least one end of the second pipe body is in sealed connection with the outer surface of the first pipe body; in a radial supporting section of the pipe cavity bracket, the first pipe body comprises at least one first radial supporting structure which is arrayed along the peripheral direction of the first pipe body; the second pipe body comprises at least one second radial supporting structure which is arrayed along the peripheral direction of the second pipe body and a covering membrane covering the second radial supporting structure; a radial deformation capability of the second radial supporting structure is greater than that of the first radial supporting structure. After the pipe cavity bracket is planted, a semi-sealed gap can be formed between the first pipe body and the second pipe body or between the second pipe body and a pipe cavity wall; blood flowing into the gap can be used as a filling material to block an I type inner leakage channel, so that the blood is prevented from flowing into tumors or an interlayer. Under the impact of the blood, the first pipe body and the second pipe body both can keep a radial supporting shape and the end faces of near ends of the first pipe body and the second pipe body are not deformed, so that the blood flowing into the pipe cavity is prevented from being blocked.
Owner:LIFETECH SCIENTIFIC (SHENZHEN) CO LTD

Quasi-close loop starting method of brushless direct current motor free of position sensor

The invention discloses a quasi-close loop starting method of a brushless direct current motor free of a position sensor, namely a quasi-close loop three-stage starting method with rotor initial position accurate pre-positioning and optimization positioning in the acceleration process combined. Short-time pulse voltage vectors are exerted in a motor winding, the rotor position can be locked in a range within 60-degree electrical angles by detecting direct-current bus current, and rotor accurate pre-positioning is completed by electrifying a designated winding, detecting current and comparing the current on the basis of rotor position locking. After rotor position pre-positioning, rotors enter the optimization positioning and acceleration stage, current differentials serve as the phase change conditions in the threshold range so that the rotors are ensured to change phase accurately in the acceleration process, and a system is switched into a counter electromotive force operation state. Experimental results show that the quasi-close loop three-stage starting method is low in cost and high in reliability, and can ensure that the system is in the quasi-close loop working state in the whole starting process and cannot have step-out and starting failure.
Owner:CENTRAL SOUTH UNIVERSITY OF FORESTRY AND TECHNOLOGY

Iterative least square method-based MIMO (multiple input multiple output) radar DOA (direction-of-arrival) estimation method

The invention discloses an iterative least square method-based MIMO (multiple input multiple output) radar DOA (direction-of-arrival) estimation method, which is characterized in that receiving and transmitting array response matrixes on which dimension-reduced processing is performed are solved by using an iterative least square method. The iterative least square method-based MIMO radar DOA estimation method comprises the following steps: firstly, performing the dimension-reduced processing on echo data matrixes of multiple radar transmitted pulses and the receiving and transmitting array response matrixes; then, establishing cost functions under the least square condition, and solving the cost functions by utilizing a gradient descent-based iterative method; finally, estimating the direction of a target by utilizing known receiving and transmitting array manifolds. Compared with a traditional monostatic MIMO radar array DOA estimation method, the iterative least square method-based MIMO radar DOA estimation method disclosed by the invention directly obtains the DOA estimation of the target, and does not need to perform spectrum peak search. Noise is effectively suppressed by adopting the dimension-reduced processing, and the estimation accuracy under low signal to noise ratio is improved; the estimation, the inversion and the eigenvalue decomposition operation of high-dimensional data covariance matrixes are avoided; the defects that the calculated amount is high and the needed sample number is large when the traditional array DOA estimation method is applied to a monostatic MIMO radar are overcome.
Owner:XIDIAN UNIV

Orthogonal frequency division multiplexing (OFDM) underwater acoustic communication parallel iterative inter-carrier interference (ICI) elimination method

The invention aims at providing an orthogonal frequency division multiplexing (OFDM) underwater acoustic communication parallel iterative inter-carrier interference (ICI) elimination method. The method includes the steps of building an OFDM underwater acoustic communication system, building an acoustic time varying multipath channel model, measuring Doppler factors in the system, estimating frequency response of a time varying channel, estimating an ICI component and a signal interference noise ratio (SINR), and carrying out parallel iterative minimum mean square error (MMSE) equilibrium to received signals. Through combination of a linear approximation method and the MMSE method, and through iteration to improve performance, the parallel iterative ICI elimination method is inducted into the OFDM underwater acoustic communication system, and the method can effectively resist the ICI generated under the underwater acoustic time varying channel, and the OFDM underwater acoustic communication system is steady in response to the change of channel time varying speed. Therefore, inverse operation of a high order matrix is avoided, complexity of the method is reduced, and arithmetic speed is improved.
Owner:三亚哈尔滨工程大学南海创新发展基地

Channel estimation method and device and pilot frequency sequence generation method and device

The invention discloses a channel evaluating device and method. A pilot frequency data is preset and then modulated. The modulated signal is subjected to space-time block coding to generate orthogonal pilot frequency sequences and the said orthogonal pilot frequency sequences are respectively sent to the transmitting terminal. The transmitting terminal respectively processes the input orthogonal pilot frequency sequences by fast Fourier transform and then sends the sequences to the receiving end. The receiving end processes the received orthogonal pilot frequency sequences by fast Fourier transform to obtain the receiving signal. The associated matrices of the orthogonal pilot frequency sequences is calculated and the associated matrices is multiplied with the receiving signal and the result is divided by power of signal sampling value and interval number to obtain the estimated value of channel. The invention can ensure the channel evaluation precision and at the same time fully show the correlated characteristic of the multi-path wireless channel, in addition the invention also uses time-domain filtering method to filter part of noise therefore the channel evaluation performance is improved, synchronously the invention can also reduce the complexity of the channel evaluating operation.
Owner:HUAWEI TECH CO LTD

Real time video image stabilization method based on simple fast global motion parameter estimation

The invention discloses a real time video image stabilization method based on simple fast global motion parameter estimation, which is simple to realize, has higher estimation prevision and provides a very effective method for real time video image stabilization under the environment of a low-speed embedded type platform. The real time video image stabilization method based on simple fast global motion parameter estimation comprises the following steps of: 1, carrying out block partition on a current frame; 2, obtaining a motion vector of each block based on a diamond search algorithm; 3, judging whether the motion is abnormal, and marking the block to be an effective block if the motion is not abnormal; 4, counting an average value of the translation invariants of all effective blocks to estimate a global translation invariant; 5, estimating rotation and zoom quantity of each effective block relative to a match block in a previous frame according to the global translation invariant; 6, counting all rotation and zoom qualities to estimate the global rotation and zoom quantity; 7, carrying out the motion filter process on the global translation invariant and the global rotation and zoom quantity; and 8, carrying out the motion compensation according to filter results.
Owner:SHANGHAI WENXIANG INFORMATION TECH

Low-complexity belief propagation detection algorithm for large-scale MIMO system

The invention discloses a low-complexity belief propagation detection algorithm for a large-scale MIMO system. A corresponding factor graph is built by utilizing an equivalent real number field model, and complex number field operation is translated into real number field operation, thereby implementing BP-based iteration detection; wherein the factor graph is used for representing a dependency relation between a receiving signal and a transmitting signal, the transmitting signal is utilized as a signal node, and the receiving signal is utilized as an observation node; each signal node updates prior information according to posterior information obtained from the observation node, and then transmits the updated prior information to all observation nodes connected with the signal node; each observation node calculates updates posterior information according to prior information obtained from the signal node, and then transmits the updated posterior information to a signal node connected with the observation node. According to the low-complexity belief propagation detection algorithm for the large-scale MIMO system, a symbol-based large-scale MIMO detection algorithm is implemented; high-dimensional matrix inversion is avoided, and the low-complexity belief propagation detection algorithm can be greatly suitable for application scenarios of the large-scale MIMO.
Owner:SOUTHEAST UNIV

SAGE (Space-alternating Generalized Expectation-maximization) based channel estimation method in CoMP multi-user system

The invention discloses an SAGE (Space-alternating Generalized Expectation-maximization) based a channel estimation method in a CoMP multi-user system, which mainly solves the problem that in a cooperative multi-point transmission CoMP multi-user system, a combined channel estimation computing method has high complexity. The method comprises the following steps: initialization and iterated initial value computing; CIR (Channel Impulse Response) estimation value iteration processing: determining the collection of selected users and collection of non-selected users of a k-th iteration, and performance of interference cancellation, CIR estimation value update, received signal reconstruction on the selected users, wherein CIR estimation values and received signal construction values of all the users in the connection of the non-selected users to a base station maintain to be same as those of a last iteration; and performance of outputting the CIR estimation values of M users to the base station. In the invention, on the base that the mean-square error property of the channel estimation is ensured, the complexity of the multi-user combined channel estimation is reduced. The method disclosed by the invention can be used for the channel estimation of the CoMP multi-user system in a wireless communication field.
Owner:天元瑞信通信技术股份有限公司

Grading-based positive and inverse reversing three-dimensional dense point set rapid registering method

The invention provides a grading-based positive and inverse reversing three-dimensional dense point set rapid registering method which comprises the following steps of: giving two point sets, wherein one point set is a reference point set, and the other point set is a target point set; solving two transformation functions, wherein the positive transformation function h is a transformation function from the reference point set to the target point set, and the inverse transformation function g is a transformation function from the target point set to the reference point set; leading h to be approximately equal to g<-1> and leading g to be approximately equal to h<-1>, wherein h<-1> and g<-1> respectively represent inverse functions of h and g; and finally obtaining a precise corresponding relation of the two point sets by the two transformation functions. Compared with the prior art, the method has the advantages of registration based on a grading way of global registration and local registration, defines an inverse consistency error and a characteristic point for local registration by utilizing a difference of the corresponding relations in the positive direction and the inverse direction, prevents complex and time-consuming function inversion operation in the traditional positive and inverse reversing registration algorithm and has simple realization, high efficiency and high registering precision.
Owner:BEIJING NORMAL UNIVERSITY

Coiling device applied to textile machinery

The invention discloses a coiling device applied to a textile machinery. The coiling device comprises a pedestal; the upper surface of the pedestal is vertically, symmetrically and fixedly connected with supporting plates; each supporting plate is of a reversed-U-shaped structure; the middle parts of the top ends of the two supporting plates are each provided with an accommodating groove; each accommodating groove is internally provided with a coiling roller; one end of each coiling roller is fixedly connected with a first gear; corresponding to the lower portion of the first gear, one side ofone supporting plate is rotationally connected with a fixing rod; the fixing rod is fixedly connected with a second gear; the second gear is engaged with the first gears; the side, corresponding to the second gear, of the fixing rod is fixedly connected with a first belt disc; the side, corresponding to one side of one supporting plate, of the upper surface of the pedestal is fixedly connected with a motor; and the output end of the motor is fixedly connected with a second belt disc. The coiling device disclosed by the invention prevents the phenomena that fabrics are coiled not closely, areeasily loosened and are not in order, is convenient to use, is also used for conveniently fixing a hard paper coiling cylinder, is simple to mount and dismount and improves the work efficiency.
Owner:安徽双盈纺织有限公司

Broadband asynchronous adjustable multi-carrier wireless transmission method and system supporting multi-antenna transmission

ActiveCN105306118ALarge transmission bandwidthData transfer without synchronizationSpatial transmit diversityMulti-frequency code systemsTransport systemCarrier signal
The invention discloses a broadband asynchronous adjustable multi-carrier wireless transmission method supporting a multi-antenna transmission. The method comprises a signal transmission step and a signal receiving step. The invention also discloses a broadband asynchronous adjustable multi-carrier wireless transmission system supporting the multi-antenna transmission. The system comprises a transmission end and a receiving end, wherein the transmission end comprises a sub-band baseband transmission module, a multi-carrier synthesis module, a D/A module, a transmission radio-frequency module and a reflecting antenna; and the receiving end comprises a receiving antenna, a reception radio-frequency module, an A/D module, a multi-carrier analysis module and a sub-band baseband receiving module. Through adoption of the method and the system, spectrum allocation is performed flexibly under a larger bandwidth on the basis of keeping the advantages of OFDM (Orthogonal Frequency Division Multiplexing); asynchronous transmission is realized; the spectrum utilization ratio is increased; the peak-to-average ratio is lowered; frequency offsets are effectively resisted; carrier side lobes are reduced; and radio resources are saved.
Owner:SOUTHEAST UNIV

Multi-cell pre-coding method for inhibiting pilot pollution in large-scale distributed antenna system

The invention relates to a multi-cell pre-coding method for inhibiting pilot pollution in a large-scale distributed antenna system, and belongs to the technical field of wireless communication. The method comprises the following steps: calculating an estimated value of an uplink channel from one user to one RAU in a central cell according to signals received by antennas on the RAU in the central cell; calculating a covariance matrix of errors in the estimated value of the uplink channel on the RAU in the central cell; calculating estimated values of channel vectors from the user to all RAUs of the central cell; calculating estimated values of channel matrixes from all users to all the RAUs of the central cell; calculating transmitting signal vectors of the central cell by conducting multi-cell pre-coding on data vectors of all the users in the central cell; and performing normalization to obtain actual vectors of signals which are finally transmitted by antennas on all the RAUs in the central cell. Through adoption of the method, the impact of pilot pollution on the downlink pre-coding performance can be effectively inhibited, the system throughput can be improved, and the pre-coding calculation complexity can be greatly reduced.
Owner:TSINGHUA UNIV
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