33 results about "Displacement error" patented technology

The invention relates to the technical field of motor control and sensors, and discloses a displacement error dynamic compensation method, device and equipment and a medium, and the method comprises the steps: obtaining the temperature data and original displacement data of a plurality of temperature measurement points in a moving part and an environment, calling a pre-built nonlinear mapping relation between a temperature gradient and a displacement deviation, and calculating the displacement error of the moving part; based on the nonlinear mapping relation, adaptive filtering is carried out on the temperature data and the original displacement data, a trend component representing temperature drift is separated out, displacement data without the trend component is obtained, and a dynamic compensation instruction is generated based on the trend component and the nonlinear mapping relation; and adjusting the displacement data of which the trend component is removed and outputting compensation displacement data. According to the method, the nonlinear mapping model of the temperature gradient and the displacement deviation is constructed, the drift trend is extracted in combination with multi-point temperature sensing and self-adaptive filtering, the compensation instruction is dynamically generated, accurate real-time correction of the displacement error is achieved, and the responsiveness and accuracy of compensation are improved.

The invention provides a spindle radial rotation error separation method based on a multi-point method. The spindle radial rotation error separation method comprises the steps that firstly, displacement data of a spindle are collected through a first directional displacement sensor and a second directional displacement sensor; step 2, inputting displacement data into an error separation model, and outputting a forward rotation error and a backward rotation error; wherein the establishment of the error separation model comprises the following steps: (1) based on kinematics analysis of a main shaft, establishing measurement data of a main shaft radial rotation error test model to obtain a direction displacement error measurement model and a direction displacement error measurement model; and (2) eliminating a sensor installation offset error and a test rod roundness error based on an improved multi-point error separation method to obtain a pure spindle radial rotation error. According to the invention, on the basis of eliminating the offset error of sensor installation and the roundness error of the test detection rod in the measurement data, the pure spindle radial rotation error is obtained, and the high-precision measurement of the spindle radial rotation error is realized.

The present application relates to the technical field of crane control, and discloses a crane double-hoist synchronous control method, comprising the following steps: collecting working condition data of the crane double-hoist in real time, calculating the synchronous speed error and displacement error of the crane double-hoist, inputting the working condition data of the crane double-hoist into a pre-trained decision tree working condition classification model, outputting a working condition type, calling a corresponding synchronous control model based on an LSTM neural network model trained for multiple working conditions according to the working condition type; based on the monitored synchronous speed error and synchronous displacement error, if the synchronous speed error and the synchronous displacement error are less than the expected control precision, further fine-tuning the control parameters, and re-examining the accuracy of the decision tree working condition classification model and the LSTM neural network synchronous control model, and optimizing and improving the model.

The invention discloses a mechanical arm control method and system for high-precision machining, and relates to the technical field of machining control. According to the method, an operation data set is constructed, a lead screw displacement error Wx (t) is calculated, and a mapping relation between time and an angle is established through a lead screw transmission ratio to obtain an angle error vector epsilon (phi); superposing and averaging the angle error vector by adopting a periodic signal superposition technology to obtain a lead screw angle error amount Es (phi); solving a fitting parameter group through a least square fitting algorithm, constructing a screw pitch error index Wwc (phi), performing dynamic error compensation on a screw rotation angle variable phi, and generating a corrected path track Xc; and calculating a periodic residual error ratio Rre of an error before and after correction by extracting actual displacement and theoretical displacement data, and evaluating a compensation state. According to the method, through time and angle domain collaborative modeling and periodic residual error closed-loop evaluation, dynamic correction and precise control over the motion error of the mechanical arm lead screw are achieved.

The application provides a method, device and system for adjusting control parameters of a robot, the method comprising: obtaining a displacement waveform of the robot collected by a displacement sensor, the displacement sensor being installed on an edge point of the robot, the edge point of the robot being an intersection between a movement direction of the robot and a shell of the robot; determining whether overshoot exists in the displacement waveform; and adjusting a position loop gain to a product of a preset multiple and a current position loop gain to reduce a probability of overshoot appearing again in the displacement waveform after a current time, in a case where it is determined that overshoot exists in the displacement waveform. The application solves the problem that the actual displacement error of the robot exceeds a tolerance error range due to a large difference between a position waveform of a robot end and a position waveform of a motor end under the same condition, and the position waveform of the motor end cannot fully reflect the actual operation of the robot.

The invention belongs to the technical field of displacement measurement, and particularly discloses a visual three-dimensional displacement measurement method based on an unmanned aerial vehicle, and the method comprises the following steps: collecting images of a to-be-measured structure before and after displacement; unmanned aerial vehicle motion compensation is carried out, pixel-level unmanned aerial vehicle motion errors are eliminated, a preliminarily processed image is obtained, and the image comprises displacement of the to-be-measured structure and sub-pixel-level displacement errors introduced by unmanned aerial vehicle motion; in combination with a sampling Moire method and industrial camera calibration, carrying out sub-pixel-level displacement measurement on the preliminarily processed image to obtain displacement data including displacement of the structure to be measured and sub-pixel-level unmanned aerial vehicle motion errors; and performing sub-pixel-level motion compensation on the displacement data to obtain sub-pixel-level error data introduced by the motion of the unmanned aerial vehicle, and subtracting the sub-pixel-level error data introduced by the motion of the unmanned aerial vehicle from the displacement data to obtain final displacement data. According to the invention, three-dimensional displacement measurement can be realized, the measurement precision is improved, and the accuracy of a displacement measurement result is ensured.

The embodiment of the present disclosure relates to a kind of self-adapting preset performance control method based on disturbance observer, comprising: the dynamic model of mechanical arm system is established;Preset performance function is constructed, preset performance function includes lower bound performance function and upper bound performance function, the angular displacement error of mechanical arm is constrained using lower bound performance function and upper bound performance function in the same direction;Under the constraint of lower bound performance function and upper bound performance function, barrier function is introduced to constrain the angular displacement error of each joint of mechanical arm, and the control error of each joint of mechanical arm is determined based on barrier function;The external disturbance of mechanical arm system is estimated using nonlinear disturbance observer, and disturbance estimation result is obtained;Controller is designed based on control error and disturbance estimation result, the external disturbance of mechanical arm system is compensated in real time using controller, and the action of each joint of mechanical arm is controlled.The present disclosure can well control angular displacement error overshoot, improve mechanical arm system stability.

The application discloses a radial magnetic bearing displacement vibration suppression method based on a phase shift reduced-order generalized integrator, and comprises the following steps: firstly, a magnetic bearing system model containing rotor mass imbalance is established; then, a synchronous displacement vibration suppression algorithm based on a phase shift reduced-order generalized integrator is designed, the orthogonal relationship of X / Y radial displacement error signals of the magnetic bearing is utilized, and the simultaneous extraction and compensation of double-channel synchronous components are realized; finally, the system stability is analyzed, and the phase shift angle parameters are designed in sections; the phase shift angle is introduced to adjust the phase without changing the amplitude characteristics at the synchronous frequency, so that the system stability is expanded. The application adopts the reduced-order generalized integrator structure, has less state quantity and lower calculation amount, and is suitable for high-speed real-time implementation of DSP / FPGA; the phase shift angle is introduced for phase advance adjustment, so that the stable working range of the algorithm can be effectively expanded; the orthogonal characteristics of the displacement signals are utilized to realize the unified implementation of X / Y double-channel synchronous compensation, and the structure is more simple.

The invention provides a speed-limiting tracking control method and system for wave motion compensation, and the method comprises the steps: obtaining the expected displacement and actual displacement at the current moment, and determining an expected speed based on a displacement error and a buffer space radius; calculating a Boolean quantity jump mark logic value; respectively solving the tracking increment of the smooth tracking expected speed and the compensation increment of the compensation displacement error; and finally, updating the current actual speed by combining the actual speed of the previous period, and indirectly controlling the actual displacement at the next moment. According to the method, a real-time position signal of an expected trajectory is only needed, a trajectory function form does not need to be predicted, any bounded unknown trajectory of which the frequency component is within the available bandwidth of the system can be tracked, the trajectory does not need to have a specific function form or conductivity, the speed in the tracking process is smooth, and speed limiting protection is achieved; the whole control algorithm is only composed of arithmetic operation and logic judgment, the calculation efficiency is high, and the method is suitable for being deployed in a low-cost programmable logic controller.

The invention belongs to the technical field of high-speed electromagnetic bearing systems, and discloses a magnetic suspension bearing rotor system and a design method thereof, and the method comprises the following steps: S1, building a mathematical model of a magnetic suspension bearing rotor control system; s2, feeding back a rotor vibration displacement signal to an input end, and comparing the rotor vibration displacement signal with an expected displacement signal of the input end to obtain a displacement error E and a displacement error change value EC; s3, taking the displacement error E and the displacement error change value EC as a fuzzy input universe of a fuzzy controller, and adjusting a proportional gain variation delta Kp, an integral gain variation delta Ki and a differential gain variation delta Kd; and S4, a wave trap is adopted to suppress resonance disturbance, and meanwhile, a particle swarm algorithm is adopted to optimize a fuzzy input discourse domain in the fuzzy controller. According to the system designed by the invention, when the rotating speed of the rotor changes, the parameters of the wave trap can be dynamically adjusted to track the change of the vibration frequency, and the optimal vibration suppression effect in the full working condition range is ensured.

The present invention discloses a force-displacement correction method for an instrumented impact test. The contact flexibility of the hammer blade and the specimen is obtained by the finite element method; a force-applying device and a laser interferometer are used to measure the flexibility of the anvil; an instrumented Charpy pendulum impact test is performed on a standard V-shaped impact specimen according to the standard, and force data during the pendulum impact on the specimen is obtained during the test. The deformation of the anvil and the hammer blade is corrected; based on the calculated corrected data, the force-displacement curve obtained from the instrumented impact test is redrawn. The method proposes an expression formula for contact flexibility, and obtains the specific parameters in this formula based on the finite element method. Based on this, the displacement error caused by the deformation of the hammer blade during the impact process is corrected; compared with the traditional method of treating the anvil and hammer blade as absolute rigid bodies, the present invention treats the hammer blade and anvil as elastic bodies, which is closer to the actual situation in principle, and the corrected data is more scientific and reasonable.

The invention relates to the technical field of networked vehicle transverse control system faults, and discloses a networked vehicle transverse control system fault estimation method based on an interval observer, which comprises the following steps: establishing a vehicle transverse dynamic model, and taking a transverse displacement error, a transverse displacement error change rate, a yaw angle error and a change rate as state variables; and constructing a continuous time state-space equation, discretizing to establish an information physical system model, and constructing a ZA-based multi-cell body region analysis method and a performance intermediate observer based on the intermediate variable. According to the method, the vehicle group formation system is abstracted into a typical information physical system model, deep fusion of a vehicle physical layer and a calculation network layer is realized, the core characteristics of a CPS system are reflected, the design freedom degree and the estimation precision are improved by introducing a novel interval observer with double auxiliary variables, and the estimation accuracy is improved. An interval fault estimation method is designed in combination with a set membership estimation thought, the robustness to unknown input is enhanced through intermediate variables, and the overall reliability of the system is improved.

The application provides a track vehicle path tracking gain adaptive modulation method using physical damping, and belongs to the technical field of unmanned driving control. The method first constructs a basic path tracking controller to obtain an initial control signal. The yaw rate loss caused by track slippage and the error amplification effect of system signal time delay when deviating from or crossing the reference path are defined as adverse factors that need to be compensated. The slowing effect of error attenuation when approaching the reference path is defined as the available physical damping characteristics. Based on the polarity combination of geometric observation variables such as heading error, displacement error and initial control signal, the vehicle motion trend is identified: when approaching the reference path, the control gain is reduced to utilize the physical damping and suppress reverse overshoot and oscillation; when deviating from or crossing the reference path, the control gain is increased to compensate for the error. The application does not depend on complex modeling, has small calculation amount and strong compatibility, and can effectively solve the problem that the existing technology cannot simultaneously improve accuracy and smoothness.

The invention discloses a control method and device for rudder angle execution devices of a ship and the ship, and belongs to the technical field of ship propulsion systems.The control method comprises the steps that motion of all the rudder angle execution devices is controlled according to a control instruction, and running state data of all the rudder angle execution devices are obtained in real time; according to the operation state data, a preset displacement tracking error boundary value and a preset speed tracking error boundary value, the acceleration tracking error of a hydraulic cylinder of each rudder angle execution device is determined; determining a control voltage of each rudder angle execution device according to the acceleration tracking error; and iteratively updating the control instruction according to the control voltage so as to realize cooperative control of each rudder angle execution device. The operation state data is limited through the displacement tracking error boundary value and the preset speed tracking error boundary value, the displacement errors and the speed errors of all the rudder angle execution devices are restrained within the unified threshold range, it is guaranteed that the steering of the multiple rudder blades is kept synchronous, and the safety of ship navigation is further guaranteed.

The application belongs to the field of grating measurement, and provides a grating interference displacement measurement method based on a network model, comprising: constructing an input vector of the network model based on measurement parameters of the grating interferometer; constructing a hidden layer transfer function based on a hidden layer nonlinear activation function and the input vector; determining a displacement error compensation value based on an output layer activation function and the hidden layer transfer function; and obtaining a compensated displacement value based on an uncompensated displacement measurement value and the displacement error compensation value. The application proposes physical guided neural architecture learning, realizes data decoupling and structured representation through "independent component coding", and injects prior knowledge as a constraint through "physical rule guidance", so as to realize high-precision, high-robustness, interpretable and physically consistent error modeling and compensation in a data-driven framework.

The application provides a kind of robust high-precision tracking control method based on dynamic sliding surface;The method is as follows: one, construct driver model.Two, introduce displacement error nonlinear dynamic function term, high-order error term and integral term in dynamic sliding surface.Three, based on the dynamic sliding surface and driver model obtained in step two, construct robust high-precision tracking sliding mode controller.Four, input the displacement error of the driver into the sliding mode controller;The sliding mode controller outputs a voltage signal to the piezoelectric driver.The application introduces displacement error nonlinear dynamic function term, high-order error term and integral term in dynamic sliding surface, the integral term improves the transient response speed of the sliding surface, reduces the steady-state error of the sliding surface;Nonlinear dynamic function improves the response speed and robustness of the sliding surface;High-order error term makes the sliding surface more sensitive to error changes.

This invention belongs to the field of CNC machining technology and discloses a method for compensating the lift error in CNC cam grinding based on the position of the drive axis. The method includes the following steps: S1. Acquire the actual contour or lift data of the cam after machining, calculate the actual displacement sequences of the C-axis and X-axis controlling the relative motion between the cam and the grinding wheel during grinding, and calculate the displacement error sequence; S2. Based on the hysteresis characteristics of the machine tool's C-axis and X-axis response, correct the C-axis coordinates in the displacement error sequence to obtain the C-axis coordinate sequence; calculate the X-axis compensation value sequence; the C-axis coordinate sequence and the X-axis compensation sequence form the displacement compensation sequence; S3. Use the displacement compensation sequence to compensate for the preset theoretical displacement sequence, and use the compensated displacement sequence to machine the cam. This invention solves the problems of complex online control parameters, limited accuracy of error back-superposition compensation, and reliance on experience for trial cutting and adjustment in existing cam machining error compensation methods.

The application relates to the field of six-degree-of-freedom motion platforms, and discloses a six-degree-of-freedom motion platform linear displacement error compensation method, which comprises the following steps: calculating theoretical pose data of an end effector according to a kinematics inverse solution model to obtain theoretical linear displacement instructions of each driving leg and control the extension and retraction of the driving leg; acquiring actual pose data to calculate pose deviation; converting the pose deviation into initial linear displacement compensation amounts for each driving leg based on a pre-constructed error mapping Jacobian matrix; correcting the theoretical linear displacement instructions based on the initial linear displacement compensation amounts to obtain target linear displacement instructions, and outputting the target linear displacement instructions to a controller to perform positioning control. Through the technical scheme, the actual tracking positioning accuracy of the end effector of the platform is improved.

The invention discloses a musical instrument use error recognition prompting method and device, and relates to the technical field of musical instrument use, and the method comprises the steps: obtaining inclination angle data corresponding to a musical instrument body, posture data and displacement data corresponding to a bow body, and hardware data and battery data of the musical instrument; based on the attitude data and the displacement data, determining a displacement error between bow hairs of the bow body and strings of the guitar body, and determining a first duration of the displacement error greater than a preset displacement error threshold; determining a second duration of an inclination angle greater than a preset inclination angle threshold value in the inclination angle data; determining an error type based on the first duration, the second duration, the hardware data, and the battery data; and according to the error type, determining a corresponding prompting mode, generating a feedback instruction based on the prompting mode, and sending the feedback instruction to the musical instrument, so that the musical instrument performs error prompting of musical instrument use based on the feedback instruction. The accuracy of recognizing errors in the musical instrument playing process is improved, and real-time error feedback is achieved.

The invention relates to a disturbance observation method and device, computer equipment, a computer readable storage medium and a computer program product. The method comprises the steps of determining a current actual input torque of a current disturbance observation period based on a previous estimated disturbance of a previous disturbance observation period under the condition that the current disturbance observation period is not the first disturbance observation period; based on the current actual input torque, outputting the current displacement error amount of the current disturbance observation period through an admittance control model; based on the current displacement error amount, determining a current estimated torque through an inverse model of an admittance control model; a current estimated perturbation for the current perturbation observation period is determined based on the current actual input torque and the current estimated torque. Therefore, the accuracy of disturbance observation is improved.

The invention relates to an error compensation method and device for a motion table, and the method comprises the steps: adjusting the displacement of the motion table moving to each first position based on a first compensation table in a process of controlling the motion table to move so as to detect a first to-be-detected workpiece, the first compensation table comprises a first displacement compensation amount needing to be adjusted when the moving table moves to each first position; determining a current residual table based on a detection position and a theoretical position of a first feature point on the first to-be-detected workpiece in the detection process, wherein the current residual table comprises second displacement compensation amounts needing to be adjusted when the motion table moves to each second position; and determining a second compensation table based on the first compensation table and the current residual table, wherein the second compensation table comprises a third displacement compensation amount which needs to be adjusted when the moving table moves to each third position. According to the method, the residual error is used for further compensating the error, a denser error compensation table can be generated, and the dynamic correction capability of the semiconductor detection equipment on the displacement error of the motion table is remarkably improved.

The invention discloses a time-delay-free angular displacement error compensation system based on real-time self-calibration, which relates to the technical field of displacement error compensation and comprises a sensing module, a core processing module and a compensation output module. Dynamic error parameters are identified on line through a real-time iterative estimation algorithm, real-time feed-forward compensation is carried out through FPGA hardware, inherent calculation delay of traditional software compensation is effectively eliminated, the real-time performance of feedback signals is ensured, and then the intelligent arbitration unit dynamically evaluates the signal quality of the multiple sensors and generates fusion weights, so that the real-time performance of the feedback signals is improved. The reliability of the system can be automatically adjusted when a single sensor has short-time abnormity or performance degradation, stable and reliable output is maintained, and the robustness and the fault-tolerant capability of the system are remarkably improved; in addition, the micro excitation device can trigger in-situ self-calibration and update a sensor dynamic model when the system is idle, so that long-term drift is inhibited, and the stability of precision in the whole life cycle is guaranteed.

The present application relates to motor control and sensor technology field, disclose a kind of displacement error dynamic compensation method, device, equipment and medium, comprising: obtaining the temperature data and original displacement data of multiple temperature measuring points in motion component inside and environment, call the nonlinear mapping relationship between temperature gradient and displacement deviation pre-constructed, temperature data and original displacement data are adaptively filtered based on the nonlinear mapping relationship, separate out the trend component characterized temperature drift, obtain the displacement data of removing trend component, generate dynamic compensation instruction based on trend component and nonlinear mapping relationship, adjust the displacement data of removing trend component and output compensation displacement data.The present application constructs the nonlinear mapping model of temperature gradient and displacement deviation, combines multiple-point temperature sensing and adaptive filtering extraction drift trend, dynamically generates compensation instruction, realizes the accurate real-time correction of displacement error, improves the responsiveness and accuracy of compensation.

The invention discloses an error compensation method of a Z-type scanning system, the Z-type scanning system and equipment. The error compensation method comprises the following steps: acquiring a first direction image acquired by the Z-type scanning system when the Z-type scanning system moves from a current layer of an object to be scanned and a second direction image acquired by the Z-type scanning system when the Z-type scanning system moves from an upper layer of the object to be scanned; calculating an image overlapping area between the first direction image and the second direction image, and determining a first image overlapping area and a second image overlapping area according to the image overlapping area; calculating a reference offset estimation value according to a first projection vector constructed by using the first image overlapping region and a second projection vector constructed by using the second image overlapping region; and selecting an offset prediction quantity in a reference offset range corresponding to the reference offset estimation value, and performing error compensation on the first direction image by using the offset prediction quantity. According to the method, accumulation of displacement errors can be inhibited in real time in the process of scanning the object to be scanned by using the Z-type scanning system.

The application discloses a displacement correction algorithm for laser collimation monitoring data and relates to the field of safety monitoring of water conservancy and hydropower projects.It comprises the following steps: step 1, grouping of measuring points;step 2, recording of distances: under a double-laser scheme, the distances from each laser collimation monitoring point and a laser emission end point to a side reference point are recorded;step 3, acquisition of data: the displacement amounts of the laser collimation monitoring points and the reference points in the same period are acquired; and step 4, correction calculation: the displacement amounts of the laser collimation monitoring points are corrected and calculated by taking the displacement amounts of the left reference point and the right reference point as true values.The monitoring values of the displacement monitoring points at the laser emission end and the laser collimation monitoring points located at the end are taken as true values, the laser collimation monitoring data are corrected and calculated, the displacement error of the measuring points caused by the instability of the laser emission end is eliminated, and the reliability of the laser collimation monitoring data is improved.

A metrology method includes obtaining a first absolute position metric of a first structure in a first layer on a substrate and a second absolute position metric of a second structure in a second layer of the substrate; and determining one or more of the following from the first absolute position metric and the second absolute position metric: exposure-induced first layer pattern displacement describing a displacement error of the first structure resulting from exposure of the structure; exposure-induced second layer pattern displacement describing a displacement error of the second structure resulting from exposure of the structure; a process-induced first layer pattern displacement describing a displacement error of the first structure resulting from the processing of the structure; and / or an alignment error describing an error of alignment data used to align the second layer with the first layer.

This invention belongs to the field of sliding diaphragm position tracking control technology, specifically relating to a preset-time anti-interference sliding diaphragm position tracking control method and system for a PMSM (Motor Particulate Module). It includes constructing a mathematical model for position tracking control of the disturbed PMSM, using the q-axis stator current as the control input for motor position tracking control, constructing an error dynamics expression based on observed position error and observed velocity error, and introducing a time-varying scaling function based on arbitrary duration. A switching time point is set within the arbitrary duration, a continuously differentiable and bounded time-varying scaling function is introduced, and then, through coordinate transformation, an interference observer is constructed, a preset-time controller is designed, and finally, the control input is obtained, enabling the mechanical angular displacement to track the desired mechanical angular displacement within a specified time range. Using the scheme of this invention, the boundedness of all closed-loop signals is guaranteed, and both the motor angular displacement error and angular velocity error converge to the equilibrium point within a preset time.

The invention relates to the technical field of computer vision, in particular to a visual displacement correction method and system based on target mutual reference and correlation analysis. According to the method, during target displacement calculation, the displacement correlation between any two targets is calculated, the two targets with the highest displacement correlation are selected firstly, and the stability of the targets is considered to be the best; the higher the displacement correlation is, the displacement is mainly derived from errors, so that the displacement errors of other targets can be corrected by performing differential calculation on the displacement of the other targets and the displacement of the reference target, self-benchmark correction is realized, and the bottleneck of stable benchmark dependence is broken through.

The invention provides a charge driving and displacement decoupling control method and system for a piezoelectric positioning table, and relates to the technical field of piezoelectric positioning table control, and the method comprises the steps: obtaining expected and actual track information when a multi-stage series piezoelectric positioning platform moves, comparing the expected and actual track information to generate displacement error information, and updating the displacement error information according to a preset sampling period; the updated error information is input into an automatic controller, and coupling disturbance variable information between platforms at all levels is extracted; based on the interference variable and expected trajectory information, decoupling interaction of all levels through a feedback control loop, and separating out interference components of all levels; solving an optimal electric signal sequence in a future finite time window according to the interference component, and converting the optimal electric signal sequence into an electric control signal through an electric drive circuit; signals are applied to the corresponding drivers, meanwhile, tail end displacement information is collected through the displacement sensors and fed back, error information is updated to form closed-loop feedback control, high-precision motion control of the platform can be achieved, and the track accuracy and stability are improved.

The utility model discloses a water tank capable of reducing displacement error, which relates to the field of bathroom water tanks and comprises a water tank body, a water inlet valve and a drain valve are arranged in the water tank body and fixedly connected to the bottom of the water tank body, the drain valve is surrounded by a retainer ring by taking the drain valve as a center, and the retainer ring is fixedly connected with the inner bottom surface of the water tank body. The lowest height of the check ring is larger than the preset water level remaining height of the drain valve, and the cross section area of the inner space of the check ring is smaller than that of the water tank body. When the water tank body is used, the water discharge error is relatively small, and the overall performance is more stable.