Abstract
High-precision reducer is the core component of industrial robots. In order to achieve the comprehensive performance testing of precision reducers, an instrument with a vertical layout and a cylindrical structure is designed. As a rotating machine, the inevitable coupling misalignment of the instrument can lead to vibration faults which lead to errors in the test. So it is pretty necessary to diagnose and monitor the coupling misalignment while the instrument is working. The causes of the coupling misaligned fault of the instrument and the relationship between the misalignment fault and torque ripple are analyzed in this paper. A method of using the torque transducer in the measurement chain of the instrument to diagnose the coupling misalignment is proposed in this paper. Many experiments have been done to test the capability of detecting the coupling misalignment using this method. Experimental results show that the amplitude of torque ripple of the shaft is linearly related to the coupling misalignment and is quadratically related to the rotation speed of the shaft when the misalignment exists in the shaft. The combination of components at the rotation frequency (fr) and the additional components can be used to diagnose faults due to coupling misalignment.
Highlights
As a core component of the actuators in robots, the robot reducer directly affects their performance factors, such as the kinematic accuracy, load capacity, and fatigue life [1].erefore, the comprehensive performance test of precision reducers is required for developing high-precision industrial robots, and it has become the focus of attention of researchers [2]
In order to solve the problem of diagnosis coupling misalignment in the vertical robot reducer detector, a method of using the torque transducer to diagnose the coupling misaligned fault of performance testing instruments of precision reducers is proposed in this paper to overcome the shortcoming of diagnosis of misaligned fault using an accelerometer or proximity probe. e paper is mainly organized as follows: Firstly, the structure of a vertical performance testing instrument of precision reducers, including guide rail mechanism, measurement module on the input side (MMIS), tested assemblies (TA), measurement module on the output side (MMOS), and workbench, is introduced in Section 2 combined with analysis of the causes of the misaligned fault
According to the analysis proposed in the above section, it can be seen that the amplitude of torque ripple of the shaft is linearly related to the misalignment of the flexible coupling and the spline coupling and is quadratically related to the rotation speed of the shaft when the parallel or angular misalignment exists in the shaft
Summary
As a core component of the actuators in robots, the robot reducer directly affects their performance factors, such as the kinematic accuracy, load capacity, and fatigue life [1]. Erefore, the comprehensive performance test of precision reducers is required for developing high-precision industrial robots, and it has become the focus of attention of researchers [2]. E reducer detector often shows vibration faults caused by shaft misalignment [5]. The methods to reduce the shaft misalignment caused by the manufacturing tolerances incur high costs and require much effort [9]. As is described above, many factors can increase misaligned faults. Erefore, a feasible method for misaligned fault diagnosis is required. Many efforts have been made to diagnose misaligned faults of rotating machinery through the combination of signal acquisition, data processing, and fault classification [18,19,20,21,22]. Due to the confusing spectral characteristics of vibration, vibrationbased misalignment detection led to less reliability [10]
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