Harmonic reducer operation state evaluation method based on strain evolution
By setting a strain measurement unit on the flexible wheel of the harmonic reducer, collecting and processing strain signals, establishing circumferential position characteristics, and constructing a benchmark model, the problem of accuracy in assessing the operating status of the harmonic reducer is solved, and direct and reliable status assessment is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2026-01-30
- Publication Date
- 2026-05-12
AI Technical Summary
In the existing technology, the operation status assessment of harmonic reducers depends on parameters such as drive current and vibration signals, which are easily affected by load, speed and environmental interference. Furthermore, the strain response of the flexure varies at different circumferential positions, leading to inaccurate assessment results.
By setting a strain measurement unit on the flexible wheel of the harmonic reducer, strain signals are continuously acquired, and a correspondence between the strain signals and the circumferential position of the flexible wheel is established based on the signal fusion layer. Strain characteristics are extracted, a benchmark model is constructed for evaluation, circumferential position difference interference is eliminated, and noise impact is reduced.
It enables direct and reliable assessment of the operating status of harmonic reducers, reduces the impact of circumferential position differences and noise on the assessment, and improves the accuracy and reliability of the assessment.
Smart Images
Figure CN122014830A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of operating status assessment of harmonic reducers, and more particularly to a method for assessing the operating status of harmonic reducers based on strain evolution. Background Technology
[0002] Harmonic reducers are widely used in collaborative robots and humanoid robots due to their advantages such as large transmission ratio and compact structure. As the core component of a harmonic reducer, the flexspline endures cyclic alternating stress during operation, and its mechanical response characteristics directly reflect the structural condition of the reducer. In existing technologies, monitoring the operating status of harmonic reducers mainly relies on parameters such as drive current, vibration signals, or transmission noise. However, these parameters typically exhibit strong coupling with the reducer's operating status and are easily affected by factors such as load, speed, and environmental interference. In contrast, obtaining information about the operating status of harmonic reducers based on the strain signal of the flexspline has more direct physical significance.
[0003] Furthermore, due to unavoidable errors in the manufacturing and assembly processes of harmonic reducers, the strain response of the flexure varies significantly at different circumferential positions, and the strain signal changes with the rotation of the harmonic reducer. Without considering the circumferential position, directly comparing strain signals acquired at different times and during different operating cycles can easily introduce large errors, affecting the accuracy of the operational status assessment results. Summary of the Invention
[0004] The technical solution of this invention: A method for evaluating the operating status of a harmonic reducer based on strain evolution, comprising the following steps:
[0005] S1. At least one strain measurement unit is provided on the flexible wheel of the harmonic reducer, and a strain amplification circuit is provided for the strain measurement unit.
[0006] S2. During the operation of the harmonic reducer, the strain signal of the strain measurement unit is continuously acquired; the output end of the harmonic reducer rotates at least one full revolution during the acquisition process to obtain a strain signal covering the full circumferential angle range of the output end of the harmonic reducer.
[0007] S3. Considering the inherent differences in strain response at different circumferential positions of the flexible wheel, in order to avoid interference with the evaluation of the operating status due to the incomparability of strain at different circumferential positions, a correspondence between the preprocessed strain signal and the circumferential position of the flexible wheel is established based on the signal fusion layer to obtain a strain signal with circumferential position characteristics, so that the strain signals collected in different motion cycles and operating stages can be compared in the same circumferential position range.
[0008] S4. Input the strain signal with circumferential position characteristics into the strain feature extraction layer, and extract the strain features at different circumferential positions of the flexible wheel to obtain strain feature sequences at different circumferential positions; the strain features include strain peak value, strain peak value change rate and / or positive and negative strain asymmetry features;
[0009] S5. Based on the strain characteristics of the harmonic reducer obtained in advance at different operating stages and in the same circumferential position range, a benchmark model reflecting the evolution law of the flexible wheel strain with operating time and operating state is constructed through the strain characteristic modeling layer.
[0010] The degradation of the operating status of a harmonic reducer is judged based on one or more of the following: peak-to-peak strain, rate of change of peak-to-peak strain, and asymmetric change of positive and negative strain at the same circumferential position.
[0011] S6. After the strain signal and the circumferential position of the flexible wheel collected by the harmonic reducer under actual working conditions are input into the signal fusion layer, they are sequentially input into the strain feature extraction layer and the strain feature modeling layer to obtain the strain feature sequence at different circumferential positions under actual working conditions, and compared with the same circumferential position in the benchmark model; based on the change of strain characteristics at the same circumferential position, the operating status of the harmonic reducer is evaluated.
[0012] The circumferential position of the flexible wheel is divided into discrete circumferential position intervals, and strain characteristics are extracted in each discrete circumferential position interval. Within the discrete circumferential position intervals, strain characteristics are extracted using the window of the input end of the harmonic reducer completing a full revolution.
[0013] Strain characteristics are obtained by one of the following methods:
[0014] Select at least one strain characteristic;
[0015] The various strain characteristics are normalized separately and then weighted and summed according to preset weights;
[0016] An importance analysis is performed on various strain characteristics to determine the weight of each strain characteristic, and a weighted sum is calculated based on the weights.
[0017] The strain signal acquired by the strain measurement unit is one or more of the following: radial strain signal, circumferential strain signal, and shear strain signal.
[0018] Before extracting the strain signal characteristics, the strain signal is normalized according to the load or temperature of the harmonic reducer.
[0019] Furthermore, it also includes 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, and the circumferential position of the output end of the harmonic reducer is obtained by the second angle measuring unit; the first angle measuring unit and the second angle measuring unit are encoders or position sensors.
[0020] The baseline model is constructed based on strain signal data collected during the entire life cycle operation of the harmonic reducer. The strain characteristics of the harmonic reducer during the entire life cycle operation are extracted, and labels are added to the strain characteristics according to the operating state of the harmonic reducer. Regression learning is performed based on the labeled dataset to establish a mapping model between strain characteristics and the operating state of the harmonic reducer.
[0021] The beneficial effects of this invention are as follows: This invention proposes a method for assessing the operating status of a harmonic reducer based on strain evolution. By discretizing the circumferential position of the flexure and aligning the strain signals collected during different operating cycles within the same circumferential position interval, the interference of strain differences at different circumferential positions on the status assessment is effectively eliminated. Simultaneously, by averaging the strain characteristics over multiple consecutive cycles, the impact of single-cycle noise on the feature extraction process is reduced. Based on the evolution law of flexure strain characteristics with operating time and operating status, this invention achieves dynamic assessment of the operating status of the harmonic reducer, providing a more direct and reliable technical means for the status assessment of harmonic reducers. Attached Figure Description
[0022] Figure 1 This is a flowchart illustrating the strain evolution-based harmonic reducer operation status evaluation method of the present invention.
[0023] Figure 2 This is a schematic diagram of the strain characteristics of the harmonic reducer during its rotation in the initial no-load state in an embodiment of the present invention.
[0024] Figure 3 This is a schematic diagram showing the strain characteristics of the harmonic reducer rotating under no-load conditions after long-term operation in an embodiment of the present invention.
[0025] Figure 4 This is a schematic diagram of the strain characteristics after the circumferential position of the harmonic reducer changes during the initial no-load state rotation process in an embodiment of the present invention.
[0026] Figure 5 This is a schematic diagram showing the strain characteristics of the harmonic reducer at different positions during a full rotation in the initial no-load state, according to another embodiment of the present invention. Detailed Implementation
[0027] The embodiments of the present invention relate to a method for evaluating the operating status of a harmonic reducer based on strain evolution, comprising the following steps:
[0028] S1. A strain measurement unit is installed on the flexible wheel of the harmonic reducer, and a strain amplification circuit for the strain measurement unit is provided.
[0029] S2. During the operation of the harmonic reducer, the strain signal of the strain measurement unit is continuously acquired. The output end of the harmonic reducer rotates at least one full revolution during the acquisition process to obtain strain signals covering the full circumferential angle range of the output end of the harmonic reducer.
[0030] S3. Considering the inherent differences in strain response at different circumferential positions of the flexible wheel, in order to avoid interference from the incomparability of strain at different circumferential positions on the evaluation of operating status, a correspondence between the preprocessed strain signal and the circumferential position of the flexible wheel is established based on the signal fusion layer to obtain a strain signal with circumferential position characteristics, so that the strain signals collected in different motion cycles and operating stages can be compared in the same circumferential position range.
[0031] S4. Input the strain signal with circumferential position characteristics into the strain feature extraction layer, extract the strain features at different circumferential positions of the flexible wheel, and obtain the strain feature sequence at different circumferential positions. The strain feature is one or more of the following: strain peak value, strain peak value change rate, and positive and negative strain asymmetry features.
[0032] S5. Based on the strain characteristics of the harmonic reducer obtained in advance at different operating stages and in the same circumferential position range, a benchmark model reflecting the evolution law of the flexible wheel strain with operating time and operating state is constructed through the strain characteristic modeling layer.
[0033] The change in the operating state of the harmonic reducer is manifested by at least one or more of the following: changes in the peak-to-peak value of strain, the rate of change of the peak-to-peak value of strain, and changes in the asymmetry of negative strain at the same circumferential position.
[0034] S6. After the strain signal and the circumferential position of the flexible wheel collected by the harmonic reducer under actual working conditions are input into the signal fusion layer, they are sequentially input into the strain feature extraction layer and the strain feature modeling layer to obtain the strain feature sequence at different circumferential positions under actual working conditions. The strain feature sequence is then compared with the same circumferential position in the benchmark model. Based on the change of strain feature at the same circumferential position, the operating status of the harmonic reducer is evaluated.
[0035] The circumferential position of the flexible wheel is divided into discrete circumferential position intervals, and strain characteristics are extracted in each discrete circumferential position interval. Within the discrete circumferential position intervals, strain characteristics are extracted using the window of the input end of the harmonic reducer completing a full revolution.
[0036] The various strain characteristics are normalized separately and then weighted and summed according to preset weights;
[0037] An importance analysis is performed on various strain characteristics to determine the weight of each strain characteristic, and a weighted sum is calculated based on the weights.
[0038] The strain signals acquired by the strain measurement unit are radial strain signals, circumferential strain signals, and / or shear strain signals.
[0039] Before extracting the strain signal characteristics, the strain signal is normalized according to the load or temperature of the harmonic reducer.
[0040] The baseline model is constructed based on strain signal data collected during the entire life cycle operation of the harmonic reducer. The strain characteristics of the harmonic reducer during the entire life cycle operation are extracted, and labels are added to the strain characteristics according to the operating state of the harmonic reducer. Regression learning is performed based on the labeled dataset to establish a mapping model between strain characteristics and the operating state of the harmonic reducer.
[0041] The method for evaluating the operating status of a harmonic reducer includes a first angle measurement unit and a second angle measurement unit. The circumferential position of the input end of the harmonic reducer is obtained by the first angle measurement unit, and the circumferential position of the output end of the harmonic reducer is obtained by the second angle measurement unit. The first angle measurement unit and the second angle measurement unit can be an encoder or a position sensor.
[0042] In the embodiment, under the same operating conditions, strain signals are collected within the same circumferential position range of the flexspline, specifically during the initial operation phase and after a long period of continuous operation of the harmonic reducer. For example... Figure 2 and 3 It can be seen that as the operating time of the harmonic reducer increases, the peak value of the strain begins to decrease, and the positive and negative symmetry of the strain waveform is significantly reduced.
[0043] Furthermore, Figure 4 The figure shows the strain distribution at different locations of the harmonic reducer. Strain characteristics extracted from different circumferential position intervals reveal the following:
[0044] Even under the same working conditions and the same operating stage, due to the processing and assembly errors of the harmonic reducer, the contact conditions at different positions around the circumference of the harmonic reducer are not completely consistent. This results in significant differences in the peak-to-peak value, rate of change, and positive and negative symmetry of strain in different circumferential position intervals, verifying the necessity of condition assessment based on the correspondence of circumferential positions.
[0045] Furthermore, Figure 5 The figure shows the strain of a harmonic reducer during a full rotation. As the rotation position changes, the strain characteristics of the flexure vary significantly. If the influence of position is not considered, it is easy to misjudge the current operating status of the harmonic reducer.
Claims
1. A method for evaluating the operating status of a harmonic reducer based on strain evolution, characterized in that, Includes the following steps: S1. At least one strain measurement unit is provided on the flexible wheel of the harmonic reducer, and a strain amplification circuit is provided for the strain measurement unit. S2. During the operation of the harmonic reducer, the strain signal of the strain measurement unit is continuously acquired; The output end of the harmonic reducer rotates at least one full revolution during the acquisition process to obtain strain signals covering the full circumferential angle range of the output end of the harmonic reducer. S3. Considering the inherent differences in strain response at different circumferential positions of the flexible wheel, in order to avoid interference with the evaluation of the operating status due to the incomparability of strain at different circumferential positions, a correspondence between the preprocessed strain signal and the circumferential position of the flexible wheel is established based on the signal fusion layer to obtain a strain signal with circumferential position characteristics, so that the strain signals collected in different motion cycles and operating stages can be compared in the same circumferential position range. S4. Input the strain signal with circumferential position features into the strain feature extraction layer, and extract the strain features at different circumferential positions of the flexible wheel to obtain strain feature sequences at different circumferential positions. Strain characteristics include peak-to-peak strain, rate of change of peak-to-peak strain, and / or positive and negative strain asymmetry. S5. Based on the strain characteristics of the harmonic reducer obtained in advance at different operating stages and in the same circumferential position range, a benchmark model reflecting the evolution law of the flexible wheel strain with operating time and operating state is constructed through the strain characteristic modeling layer. The operating status of a harmonic reducer is determined based on one or more of the following: peak-to-peak strain, rate of change of peak-to-peak strain, and asymmetric change of positive and negative strain at the same circumferential position. S6. After the strain signal and the circumferential position of the flexible wheel collected by the harmonic reducer under actual working conditions are input into the signal fusion layer, they are sequentially input into the strain feature extraction layer and the strain feature modeling layer to obtain the strain feature sequence at different circumferential positions under actual working conditions, and compared with the same circumferential position in the benchmark model; based on the change of strain characteristics at the same circumferential position, the operating status of the harmonic reducer is evaluated.
2. The method for evaluating the operating status of a harmonic reducer based on strain evolution according to claim 1, characterized in that, The circumferential position of the flexible wheel is divided into discrete circumferential position intervals, and strain characteristics are extracted in each discrete circumferential position interval. Within the discrete circumferential position range, strain features are extracted using a window that takes one full rotation of the input end of the harmonic reducer.
3. The method for evaluating the operating status of a harmonic reducer based on strain evolution according to claim 1, characterized in that, The strain characteristics are obtained by one of the following methods: Select at least one of the strain characteristics; The various strain characteristics are normalized respectively, and then weighted and summed according to preset weights; An importance analysis is performed on the various strain characteristics to determine the weight of each strain characteristic, and a weighted sum is calculated based on the weights.
4. The method for evaluating the operating status of a harmonic reducer based on strain evolution according to claim 1, characterized in that, The strain signal acquired by the strain measurement unit is one or more of radial strain signal, circumferential strain signal, and shear strain signal.
5. The method for evaluating the operating status of a harmonic reducer based on strain evolution according to claim 1, characterized in that, Before extracting the strain signal features, the strain signal is normalized according to the load or temperature of the harmonic reducer.
6. The method for evaluating the operating status of a harmonic reducer based on strain evolution according to claim 1, characterized in that, It also includes 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, and the circumferential position of the output end of the harmonic reducer is obtained by the second angle measuring unit; the first angle measuring unit and the second angle measuring unit are encoders or position sensors.