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CN-121323503-B - High-precision detection method for tail end displacement of industrial mechanical arm based on photoelectric interference

CN121323503BCN 121323503 BCN121323503 BCN 121323503BCN-121323503-B

Abstract

The invention discloses a high-precision detection method for end displacement of an industrial mechanical arm based on photoelectric interference, which relates to the technical field of precision measurement and detection and comprises the following steps of S1, collecting photoelectric interference signals, performing down-conversion filtering to obtain complex envelope signals, S2, calculating a preliminary displacement observation value based on accumulated phases of the complex envelope signals, S3, collecting equipment information to construct a sensing data set to generate a multi-source error state vector, S4, generating a purification displacement value by utilizing extended Kalman filtering to reject errors, S5, calculating an air refractive index according to real-time environment parameters, and compensating the purification displacement value by combining with a reference air refractive index to generate a correction displacement value. And high-precision, stability and robustness measurement of the end displacement of the industrial mechanical arm are realized through multi-source sensor fusion, kalman filtering error estimation and air refractive index compensation.

Inventors

  • QIU MINGQING

Assignees

  • 广州市晟茂光电科技有限公司

Dates

Publication Date
20260508
Application Date
20251120

Claims (7)

  1. 1. The high-precision detection method for the end displacement of the industrial mechanical arm based on photoelectric interference is characterized by comprising the following steps of: S1, acquiring two paths of orthogonal interference electric signals output by a photoelectric interference module, and performing digital down-conversion and filtering processing to acquire a complex envelope signal; S2, carrying out differential operation on a complex envelope signal to obtain an instantaneous phase increment for accumulation to obtain an accumulated optical phase, and calculating to obtain a preliminary displacement observation value according to the mapping relation between the accumulated optical phase and a laser wavelength to construct a displacement observation basis set, wherein the accumulated optical phase acquisition comprises the steps of carrying out short-time complex domain smoothing on a complex envelope signal sequence to inhibit high-frequency noise, and then calculating the difference value of adjacent sampling points to construct a complex difference; The method comprises the steps of S3, collecting equipment information to construct a sensing data set to generate a multisource error state vector, wherein the S3 comprises the steps of collecting equipment multisource sensor data to construct an equipment sensing data set, wherein the sensing data set comprises joint position numbers, joint position coordinates, joint angles, joint and structure temperatures, triaxial accelerometer signals and gyroscope signals, calculating a theoretical end position according to the joint position numbers, the joint position coordinates, the joint angles, preliminary displacement observations and preset nominal kinematic parameters, differentiating the theoretical end position with the preliminary displacement observations to obtain residual signals, estimating correction amounts related to the nominal kinematic parameters based on the residual signals, mapping the correction amounts to kinematic deviations, calculating displacement changes caused by thermal expansion of structures according to joint and structure temperatures and driver working time information of a mechanical arm, setting the displacement changes to be thermal displacement deviations according to triaxial accelerometer signals and gyroscope signals at the tail end of the mechanical arm, calculating deviation of the tail end according to the vibration state data sequences, calculating deviation of the tail end vibration positions according to the vibration state data sequences and a structure dynamics model, calculating the deviation of the tail end vibration positions according to the vibration state data sequences, and using the vibration state data sequences and the vibration state data sequence as vibration state data, and the vibration state data frames, and directly calculating vibration state data of vibration state data, and vibration state data, vibration state data and vibration state data; S4, carrying out optimal estimation on the multi-source error state vector based on an extended Kalman filtering algorithm, separating the optimal estimated multi-source error state vector from the preliminary displacement observation value, and generating a purifying displacement value; And S5, calculating the air refractive index according to the environmental parameters acquired in real time, and compensating the purified displacement value by combining the preset reference air refractive index to finally generate a corrected displacement value.
  2. 2. The method for detecting the end displacement of the industrial mechanical arm with high precision based on photoelectric interference according to claim 1, wherein the step S1 comprises the following steps: the method comprises the steps that a photoelectric interference module is arranged at the tail end of a mechanical arm, and a measuring beam is emitted to point to a fixedly arranged reference mirror, wherein the measuring beam is laser with a fixed wavelength; receiving interference light signals by using a photoelectric detector, converting the interference light signals into two paths of orthogonal interference voltage signals, and synthesizing the two paths of orthogonal interference voltage signals which are synchronously sampled into complex measurement signals; Multiplying the complex measurement signal with a preset digital local oscillation sequence to carry out digital down-conversion, wherein the angular frequency of the digital local oscillation sequence is equal to the frequency shift angular frequency of an acousto-optic modulator in the photoelectric interference module; and performing digital low-pass filtering on the down-converted signal to obtain a complex envelope signal.
  3. 3. The method for detecting the end displacement of the industrial mechanical arm with high precision based on the photoelectric interference according to claim 1, wherein, Monitoring the complex envelope signal in real time, and extracting the module length amplitude of the complex envelope signal as a quality index; and when the quality index is lower than a preset threshold, judging that the signal quality is invalid, suspending the phase accumulation process and triggering the resampling process.
  4. 4. The method for detecting the end displacement of the industrial mechanical arm with high precision based on the photoelectric interference according to claim 3, wherein, When the quality index is not lower than a preset threshold, multiplying the accumulated optical phase by a preset proportionality coefficient to obtain a preliminary displacement observation value, wherein the proportionality coefficient is the ratio of the laser vacuum wavelength to the constant four times of the circumference rate, and the laser vacuum wavelength is obtained from the laser parameters of the photoelectric interference module; Attaching a current system time stamp and a quality index to each preliminary displacement observation value; integrating the accumulated optical phase, the preliminary displacement observation value, the time stamp and the quality index to construct a displacement observation basic set.
  5. 5. The method for detecting the end displacement of the industrial mechanical arm with high precision based on photoelectric interference according to claim 1, wherein the step S4 comprises: Establishing a state transition model and an observation model based on the multi-source error state vector, and estimating and updating the multi-source error state vector in real time by using an extended Kalman filtering method; And removing the multisource error state vector after Kalman filtering estimation and updating from the preliminary displacement observation value to obtain a purified displacement value.
  6. 6. The method for detecting the end displacement of the industrial mechanical arm with high precision based on photoelectric interference according to claim 1, wherein the step S5 comprises: Acquiring real-time environmental parameters through an air pressure sensor, a temperature sensor and a humidity sensor, and constructing environmental state data; And inputting the environmental state data into a preset refractive index estimation model, and outputting the current air refractive index, wherein the refractive index estimation model is constructed based on a polynomial approximation method.
  7. 7. The method for detecting the end displacement of the industrial mechanical arm with high precision based on the photoelectric interference according to claim 6, wherein, The method comprises the steps of adjusting a reference air refractive index preset in a system calibration stage, and comparing a current air refractive index with the reference air refractive index to obtain an air refractive index deviation; inputting the air refractive index deviation into a displacement compensation unit, wherein the displacement compensation unit maps the refractive index deviation into a displacement correction amount based on a preset calibration coefficient; And subtracting the displacement correction value from the purified displacement value based on the purified displacement value to finally generate a corrected displacement value.

Description

High-precision detection method for tail end displacement of industrial mechanical arm based on photoelectric interference Technical Field The invention relates to the technical field of precision measurement and detection, in particular to a high-precision detection method for the tail end displacement of an industrial mechanical arm based on photoelectric interference. Background Industrial robot arms have wide application in manufacturing tasks in high precision assembly, micro-operations, and complex environments. For the motion control and the operation precision of the mechanical arm end effector, the displacement detection technology is a key link. The existing displacement detection method mainly comprises joint angle detection based on an encoder, spatial position measurement based on vision, high-precision detection based on laser interference and the like. The encoder mode is limited by the accumulation of errors of a joint transmission chain, the accuracy of absolute displacement of the tail end is difficult to ensure, the vision measurement mode is poor in robustness under illumination, shielding and complex environments, the accuracy is limited by imaging resolution and calibration errors, and the laser interferometry has extremely high resolution and stability, but is still subject to interference of factors such as interference signal quality fluctuation, environment refractive index change, thermal effect, structural vibration and the like under complex industrial environments, so that a certain deviation exists in detection results. Therefore, how to improve the stability and accuracy of the end displacement detection of the mechanical arm in a complex industrial environment has become a technical problem to be solved in the field. Disclosure of Invention Based on the defects of the prior art, the invention aims to provide a high-precision detection method for the tail end displacement of an industrial mechanical arm based on photoelectric interference so as to solve the technical problems. In order to achieve the purpose, the invention provides the technical scheme that the high-precision detection method for the end displacement of the industrial mechanical arm based on photoelectric interference comprises the following steps: S1, acquiring two paths of orthogonal interference electric signals output by a photoelectric interference module, and performing digital down-conversion and filtering processing to acquire a complex envelope signal; s2, carrying out differential operation based on complex envelope signals to obtain instantaneous phase increment for accumulation to obtain accumulated optical phase, calculating to obtain a preliminary displacement observation value according to the mapping relation between the accumulated optical phase and laser wavelength, and constructing a displacement observation basic set; s3, collecting equipment information to construct a sensing data set, and generating a multi-source error state vector; S4, carrying out optimal estimation on the multi-source error state vector based on an extended Kalman filtering algorithm, separating the optimal estimated multi-source error state vector from the preliminary displacement observation value, and generating a purifying displacement value; And S5, calculating the air refractive index according to the environmental parameters acquired in real time, and compensating the purified displacement value by combining the preset reference air refractive index to finally generate a corrected displacement value. The present invention is further configured such that the S1 includes: the method comprises the steps that a photoelectric interference module is arranged at the tail end of a mechanical arm, and a measuring beam is emitted to point to a fixedly arranged reference mirror, wherein the measuring beam is laser with a fixed wavelength; receiving interference light signals by using a photoelectric detector, converting the interference light signals into two paths of orthogonal interference voltage signals, and synthesizing the two paths of orthogonal interference voltage signals which are synchronously sampled into complex measurement signals; Multiplying the complex measurement signal with a preset digital local oscillation sequence to carry out digital down-conversion, wherein the angular frequency of the digital local oscillation sequence is equal to the frequency shift angular frequency of an acousto-optic modulator in the photoelectric interference module; and performing digital low-pass filtering on the down-converted signal to obtain a complex envelope signal. The present invention is further configured such that the S2 includes: Short-time complex domain smoothing is firstly carried out on the complex envelope signal sequence to inhibit high-frequency noise, and then the difference value of adjacent sampling points is calculated to construct complex difference; Obtaining an instantaneous phase increment based o