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Bearing fault diagnosis is of great importance to maintain the high reliability and long-term safe operation of rotating machinery. The key factor of the processing result is the proper selection of basis, which is also called dictionary in sparse representation. In this paper, a data-driven method for designing dictionaries called singular value decomposition (SVD)-based dictionary learning method...
In practice, fluctuations around the nominal operating speed often result in vibration spectra of gearboxes to appear smeared. Order tracking technique can be employed to remove the spectral smearing of such signals. However, this technique requires simultaneous measurements of vibration and rotational speed, which is often unavailable in industrial settings. Thus, a new diagnostic algorithm without...
A potentiostat/galvanostat system is used for conducting electrochemical experiments in aqueous environments. The conventional method is to use one sample for investigation in each experiment. To maximize the usage of a single unit electrochemical testing system, a multi-sample and multi-channel technique was developed to simultaneously test multiple metal samples. In this paper, the following are...
Demodulation of the measured signal to detect faults has been a widely used prominent technique in fault diagnosis of rotating machines. This paper proposes a novel demodulation method called short-time smoothness spectrum (STSS) for bearing fault diagnosis. With a sliding window on the raw signal, the smoothness index (SI) is calculated for each short-time signal to detect the impulsive performance...
A fundamental challenge in digital and sampled-data control arises when the continuous-time plant is subject to fast disturbances that possess significant frequency components beyond Nyquist frequency. Such intrinsic difficulties are more and more encountered in modern manufacturing applications, where the measurement speed of the sensor is physically limited compared to the plant dynamics. The paper...
In recent times, there has been growing demand for environmentally friendly methods for finishing freeform surfaces (e.g., molding-die surfaces). This demand has generated interest in the development of a new polishing technology that uses less abrasive slurry and employs magnetic abrasive finishing. However, it is well known that the traditional magnetic polishing method is unstable and produces...
This study discusses a design method for a sampled-data multi-rate control system in which the sampling interval of the plant output is an integer multiple of the hold interval of the control input. In this study, a pre-designed multi-rate control law is extended such that the sampled behavior is maintained. Using the extended control law, both the transient and steady-state intersample behavior can...
It is necessary for the STEP-NC controllers to interpret STEP-NC file directly in order to make use of high-level product manufacturing information. In this paper, a STEP-NC interpreter is proposed and implemented based on open CNC platform. Two interfaces named IInterpreter and ITaskGenerator are defined and encapsulated into COM modules by using C++. The mechanism for interpreting and executing...
This paper studies slip in friction drives in the context of a precision servo positioner equipped with a twist-roller friction drive. The servo positioner is modeled using a two-mass model that includes the experimentally-identified nonlinear slip dynamics of the friction drive. The model is then used to design an observer-based compensation scheme aimed at reducing the slip-induced performance degradation...
This work focuses on the application of Sliding Mode Controller with uncertainty learning and control gain estimation techniques to provide the desired climatic conditions in the poultry house. The nonlinear dynamics mathematical model was derived from physical governing equations of the industrial scale system and was validated under the hot and humid climate conditions of Thailand, along with fluctuation...
Computed order tracking is a kind of algorithm which is generally used to eliminate the effect of varying rotational speed on the rotary machines. However, it is impropriate to use the computed order tracking algorithm and its corresponding analysis techniques on the fault diagnosis of the rolling element bearing unless the peak time of the fault induced impulse is set as zero which cannot be met...
Feature extraction is an important step in conventional vibration-based fault diagnosis methods. However, the features are usually empirically extracted, leading to inconsistent performance. This paper presents a new automatic and intelligent fault diagnosis method based on convolution neural network. Firstly, the vibration signal is processed by wavelet transform into a multi-scale spectrogram image...
Aiming at automated and intelligent state monitoring of induction motors, which are an integral component of a broad spectrum of manufacturing machines, this paper presents a Deep Belief Network (DBN)-based approach to automatically extract relevant features from vibration signals that characterize the working condition of an induction motor. The DBN model employs a structure with stacked restricted...
Plant factories daily produce large amount of high quality vegetables under artificially controlled environments. One of the important problems to be considered is to establish suitable storage systems to achieve an acceptable length of shelf life and to minimize the risk to food borne illnesses. Temperature control is an essential part of food storage in food production and distribution network....
Machine learning techniques have been widely investigated in gearbox diagnosis with the assumption that training data and test data follow the same distributions. However, various operating conditions inevitably cause dynamic changes of gearbox fault characteristics which pose significant challenges on gearbox diagnosis. To address this issue, this paper introduces a transfer learning method to mitigate...
Dynamic instability in the form of chatter is a highly undesirable phenomenon that occurs during machining, resulting in poor surface finish and reduced tool life. Though analytical models exist for identifying conditions that avoid chatter, they do not account for process uncertainties or they require extensive cutting tests. Therefore, an on-line chatter detection algorithm is required to detect...
Forming pressure distribution on the roll surface is one of the key parameters determining quality of product in microrolling process. Prior work has led to the design, characterization, and prototyping of a roll-embedded capacitive sensing method to measure pressure distribution on the roll surface on a single line, along the axis direction. This paper reports on research that has expanded the sensing...
Ultrasound generators have been studied for ultrasound non-destructive testing (NDT) and biomedical ultrasound imaging. Fiber-optic ultrasound generators, based on photoacoustic (PA) principle, are promising devices for these applications. Their compact sizes enable them to work in restricted space; the acoustic properties of the ultrasound signal can be easily tailored by the optical signal. This...
Due to the dramatic growth of total installation and individual capacity make the failures of wind turbines costly or even unacceptable. Therefore, wind turbine fault diagnosis, which is considered as a useful tool to ensuring the safety of wind turbines and reducing costly system maintenances, is attracting increasing attention. In this paper, a novel fault diagnosis for wind turbine gearbox based...
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