CN-122014830-A - Harmonic reducer running state evaluation method based on strain evolution

CN122014830ACN 122014830 ACN122014830 ACN 122014830ACN-122014830-A

Abstract

The invention belongs to the field of operation state evaluation of harmonic reducers, and discloses a method for evaluating the operation state of a harmonic reducer based on strain evolution. The strain characteristics corresponding to different circumferential positions are extracted by corresponding the output signals of the strain measurement units arranged on the harmonic reducer flexspline to the circumferential positions of the flexspline. And constructing a reference model reflecting the change of the flexible gear strain along with the running time and the running state based on the strain characteristics of the harmonic reducer obtained in different running stages and in the same circumferential position interval. And comparing the strain characteristics acquired under the actual working condition with the historical strain characteristics of the reference model, and evaluating the running state of the harmonic reducer. According to the invention, the flexible gear strain evolution characteristic is used as an information source for evaluating the running state of the harmonic reducer, a strain characteristic modeling mode associated with the circumferential position of the flexible gear is introduced, the problem that a method based on current or vibration information is sensitive to the change of the running working condition in the state evaluation process is reduced, and a new technical approach is provided for evaluating the running state of the harmonic reducer.

Inventors

WANG XIAODONG
SHEN WENQIANG
LOU ZHIFENG
LI JIACHENG
AN ZE
LUO YI

Assignees

大连理工大学

Dates

Publication Date: 20260512
Application Date: 20260130

Claims (6)

1. The method for evaluating the running state of the harmonic reducer based on strain evolution is characterized by comprising the following steps of: s1, arranging at least one strain measurement unit on a harmonic reducer flexible gear, and arranging a strain amplifying circuit of the strain measurement unit; S2, continuously acquiring a strain signal of the strain measurement unit in the operation process of the harmonic reducer, wherein the output end of the harmonic reducer rotates for at least one whole circle in the acquisition process so as to obtain a strain signal covering the circumferential full-angle range of the output end of the harmonic reducer; S3, considering that the strain responses at different circumferential positions of the flexible gear have inherent differences, in order to avoid interference of incomparabilities of strains at different circumferential positions on the running state evaluation, establishing a corresponding relation between the preprocessed strain signals and the circumferential positions of the flexible gear based on a signal fusion layer to obtain strain signals with circumferential position characteristics, so that the strain signals acquired at different movement periods and running stages are compared in the same circumferential position interval; S4, inputting the strain signals with the circumferential position characteristics into a strain characteristic extraction layer, and respectively extracting strain characteristics of different circumferential positions of the flexible gear to obtain strain characteristic sequences of different circumferential positions, wherein the strain characteristics comprise strain peak-to-peak values, strain peak-to-peak value change rates and/or positive and negative strain asymmetry characteristics; S5, constructing a reference model reflecting the evolution rule of the flexible gear strain along with the running time and the running state through a strain characteristic modeling layer based on the strain characteristics obtained in advance by the harmonic reducer in different running stages and in the same circumferential position interval; Judging the running state of the harmonic reducer according to one or more than two of strain peak-to-peak value, strain peak-to-peak value change rate and positive and negative strain asymmetry change at the same circumferential position; S6, inputting strain signals acquired by the harmonic reducer under the actual working condition and the circumferential position of the flexible gear into the signal fusion layer, sequentially inputting the strain signals into the strain characteristic extraction layer and the strain characteristic modeling layer, acquiring strain characteristic sequences of different circumferential positions under the actual working condition, comparing the strain characteristic sequences with the same circumferential position in the reference model, and evaluating the running state of the harmonic reducer according to the change of the strain characteristics at the same circumferential position.
2. The method for evaluating the running state of the harmonic reducer based on strain evolution according to claim 1, wherein the circumferential position of the flexible gear is divided into discrete circumferential position sections, strain features are extracted in each discrete circumferential position section, and strain feature extraction is performed in the discrete circumferential position sections by taking the input end of the harmonic reducer as a window after one whole revolution.
3. The method for evaluating the operating state of a harmonic reducer based on strain evolution according to claim 1, wherein the strain characteristics are obtained by one of the following means: Selecting at least one from the strain features; Respectively carrying out normalization processing on the plurality of strain characteristics, and carrying out weighted summation according to preset weights; And analyzing the importance degree of the plurality of strain characteristics, determining the weight of each strain characteristic, and carrying out weighted summation according to the weight.
4. The method for evaluating the running state of the harmonic reducer based on strain evolution according to claim 1, wherein the strain signal obtained by the strain measurement unit is one or more of a radial strain signal, a circumferential strain signal and a shear strain signal.
5. The method for evaluating the running state of the harmonic reducer based on strain evolution according to claim 1, wherein the strain signal is normalized according to the load or the temperature of the harmonic reducer before the strain signal characteristics are extracted.
6. The method for evaluating the running state of the harmonic reducer based on strain evolution according to claim 1, further comprising a first angle measuring unit and a second angle measuring unit, wherein the circumferential position of the input end of the harmonic reducer is obtained by the first angle measuring unit, the circumferential position of the output end of the harmonic reducer is obtained by the second angle measuring unit, and the first angle measuring unit and the second angle measuring unit are encoders or position sensors.

Description

Harmonic reducer running state evaluation method based on strain evolution Technical Field The invention relates to the field of operation state evaluation of harmonic reducers, in particular to a method for evaluating the operation state of a harmonic reducer based on strain evolution. Background The harmonic reducer is widely applied to cooperative robots and humanoid robots due to the advantages of large transmission ratio, compact structure and the like. As a core component of the harmonic reducer, the flexible gear bears periodic alternating stress for a long time in the working process, and the mechanical response characteristic of the flexible gear can directly reflect the structural condition of the harmonic reducer. In the prior art, the monitoring of the running state of the harmonic reducer mainly depends on parameters such as driving current, vibration signals of the harmonic reducer or noise in a transmission process, however, a strong working condition coupling relation exists between the parameters and the running state of the harmonic reducer, and the parameters are easy to be influenced by factors such as load, movement speed and environmental interference. In contrast, the strain signal based on the flexible gear has more direct physical significance in acquiring the running state information of the harmonic reducer. In addition, because the harmonic reducer inevitably has errors in the processing and assembling processes, obvious differences exist in strain response of the flexible gear at different circumferential positions, and strain signals change along with rotation of the harmonic reducer. Under the condition that the circumferential position is not introduced, the strain signals acquired at different moments and in different running periods are directly compared, and larger errors are easily introduced to influence the accuracy of the running state evaluation result. Disclosure of Invention The technical scheme of the invention is that the method for evaluating the running state of the harmonic reducer based on strain evolution comprises the following steps: s1, arranging at least one strain measurement unit on a harmonic reducer flexible gear, and arranging a strain amplifying circuit of the strain measurement unit; S2, continuously acquiring a strain signal of the strain measurement unit in the operation process of the harmonic reducer, wherein the output end of the harmonic reducer rotates for at least one whole circle in the acquisition process so as to obtain a strain signal covering the circumferential full-angle range of the output end of the harmonic reducer; S3, considering that the strain responses at different circumferential positions of the flexible gear have inherent differences, in order to avoid interference of incomparabilities of strains at different circumferential positions on the running state evaluation, establishing a corresponding relation between the preprocessed strain signals and the circumferential positions of the flexible gear based on a signal fusion layer to obtain strain signals with circumferential position characteristics, so that the strain signals acquired at different movement periods and running stages are compared in the same circumferential position interval; S4, inputting the strain signals with the circumferential position characteristics into a strain characteristic extraction layer, and respectively extracting strain characteristics of different circumferential positions of the flexible gear to obtain strain characteristic sequences of different circumferential positions, wherein the strain characteristics comprise strain peak-to-peak values, strain peak-to-peak value change rates and/or positive and negative strain asymmetry characteristics; S5, constructing a reference model reflecting the evolution rule of the flexible gear strain along with the running time and the running state through a strain characteristic modeling layer based on the strain characteristics obtained in advance by the harmonic reducer in different running stages and in the same circumferential position interval; judging the running state degradation of the harmonic reducer according to one or more than two of strain peak-to-peak value, strain peak-to-peak value change rate and positive and negative strain asymmetry change at the same circumferential position; S6, inputting strain signals acquired by the harmonic reducer under the actual working condition and the circumferential position of the flexible gear into the signal fusion layer, sequentially inputting the strain signals into the strain characteristic extraction layer and the strain characteristic modeling layer, acquiring strain characteristic sequences of different circumferential positions under the actual working condition, comparing the strain characteristic sequences with the same circumferential position in the reference model, and evaluating the running state of the harmonic reducer according to the