Vibration faults simulation system (VFSS): A lab equipment to aid teaching of mechatronics courses

VFSS is an example of a mechatronics system which involves data acquisition and analysis using LabVIEW-based virtual instrument technology. This system can serve as teaching equipment for mechatronics students in the area of data acquisition, sensors and actuators, signal processing and vibration monitoring to aid students' understanding on these subjects. Since vibration fault signals and their causes are important for fault detection and diagnosis, a vibration faults simulation system is developed to gain good understanding of such signals. To achieve this a vibration faults simulation rig (VFSR) is designed and developed to simulate and study most common vibration fault signatures encountered in rotating machines. A LabVIEW-based data acquisition system is used to acquire and analyze the fault signals. The complete system has been developed and tested and the fault signals were compared with normal signals so as to ascertain the condition of the machine under investigation. VFSS has been successfully used to demonstrate some vital concepts in the teaching of DSP, sensor and actuators and mechanical vibration since data are acquired from the physical system and are analyzed to derive information on the system under investigation. This approach further allows students to gain insight into effects of noise on measurements and how such effects can be combated

A LabVIEW based data acquisition system for vibration monitoring and analysis

LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is gaining popularity as a graphical programming language, especially for data acquisition and measurement. This is due to the vast array of data acquisition cards and measurement systems which can be supported by LabVIEW as well as the relative ease with which advanced software can be programmed. One area of application of LabVIEW is the monitoring and analysis of vibration signals. The analysis and monitoring of the signal are of concern for fault detection and predictive maintenance. This paper describes LabVIEW based data acquisition and analysis developed specifically for vibration monitoring and used with vibration fault simulation systems (VFSS). On-line displays of time and frequency domains of the vibration signal provide a user-friendly data acquisition interface

Machine condition monitoring and fault diagnosis using spectral analysis techniques

There is need to continuously monitor the conditions of complex, expensive and process-critical machinery in order to detect its incipient breakdown as well as to ensure its high performance and operating safety. Depending on the application, several techniques are available for monitoring the condition of a machine. Vibration monitoring of rotating machinery is considered in this paper so as develop a selfdiagnosis tool for monitoring machines’ conditions. To achieve this a vibration fault simulation rig (VFSR) is designed and constructed so as to simulate and analyze some of the most common vibration signals encountered in rotating machinery. Vibration data are collected from the piezoelectric accelerometers placed at locations that provide rigid vibration transmission to them. Both normal and fault signals are analyzed using the singular value decomposition (SVD) algorithm so as to compute the parameters of the auto regressive moving average (ARMA) models. Machine condition monitoring is then based on the AR or ARMA spectra so as to overcome some of the limitations of the fast Fourier transform (FFT) techniques. Furthermore the estimated AR model parameters and the distribution of the singular values can be used in conjunction with the spectral peaks in making comparison between healthy and faulty conditions. Different fault conditions have been successfully simulated and analyzed using the VFSR in this paper. Results of analysis clearly indicate that this method of analysis can be further developed and used for self-diagnosis, predictive maintenance and intelligent-based monitoring

Active vibration control of a beam with piezoelectric patches: real-time implementation with xPC target

Active control of a vibrating beam using smart materials such as piezoelectric materials is examined in this paper. A model based on Euler-Bernoulli beam equation has been developed and then extended with bonded three piezoelectric patches which act as sensor, actuator and exciter. The sensor and actuator are collocated to achieve a minimum phase. The aim of this research work is to control the first three resonant modes. To achieve this, a compensated inverse PID controller is developed and tuned to damp these modes using MATLAB. The designed controller for damping each mode is then combined in parallel to damp any of the three modes. Finally, the simulation results are verified experimentally and the real-time implementation is carried out with xPC target toolbox in MATLAB

Improving μ-wire electro-discharge machining operation of polished silicon wafer by conductive coating

Micro-Wire Electro-discharge machining (-WEDM) is a nonconventional machining technology which is extensively used for metal based micro fabrication process. This is a non-contact machining process where material removal is taken place by electro-thermal action. -WEDM process is difficult to be applied for semiconductor material like Silicon (Si). In this paper a new approach is proposed for machining polished Si (p-type, resistivity 1-50 -cm) wafer. In this method, initially Si workpiece is coated with a conductive material (gold for this study) and then -WEDM operation is carried out. Finally, after WEDM operation, the conductive layer is removed from the polished Si substrate without damaging the substrate. WEDM process stability was found to be improved (up to 60 times for certain machining condition) if coated Si wafer is used as compared to uncoated Si workpiece. Material removal rate was also found to be increased by a good margin (~ 100% maximum) for coated Si wafer. Overall this new method of -WEDM operation of polished Si wafer has been found to be more efficient and useful

Voltage supply and voltage regulation

A stable voltage supply is important for the proper operation of electronic devices. Stability is characterized by the ability of the voltage output to stay constant and ripplefree regardless of how much load is connected to the circuit. There is a brief discussion on how much inaccuracy is caused by voltage supplies which are prone to voltage fluctuations due to switching phenomenon taking place in the circuit, load fluctuations or temperature change

Machine condition monitoring and fault diagnosis using spectral analysis techniques

There is need to continuously monitor the conditions of complex, expensive and process-critical machinery in order to detect its incipient breakdown as well as to ensure its high performance and operating safety. Depending on the application, several techniques are available for monitoring the condition of a machine. Vibration monitoring of rotating machinery is considered in this paper so as develop a selfdiagnosis tool for monitoring machines’ conditions. To achieve this a vibration fault simulation rig (VFSR) is designed and constructed so as to simulate and analyze some of the most common vibration signals encountered in rotating machinery. Vibration data are collected from the piezoelectric accelerometers placed at locations that provide rigid vibration transmission to them. Both normal and fault signals are analyzed using the singular value decomposition (SVD) algorithm so as to compute the parameters of the auto regressive moving average (ARMA) models. Machine condition monitoring is then based on the AR or ARMA spectra so as to overcome some of the limitations of the fast Fourier transform (FFT) techniques. Furthermore the estimated AR model parameters and the distribution of the singular values can be used in conjunction with the spectral peaks in making comparison between healthy and faulty conditions. Different fault conditions have been successfully simulated and analyzed using the VFSR in this paper. Results of analysis clearly indicate that this method of analysis can be further developed and used for self-diagnosis, predictive maintenance and intelligent-based monitoring

Compensated inverse PID controller for active vibration control with piezoelectric patches: modeling, simulation and implementation

Active vibration control of the first three modes of a vibrating cantilever beam using collocated piezoelectric sensor and actuator is examined in this paper. To achieve this, a model based on Euler-Bernoulli beam equation is adopted and extended to the case of three bonded piezoelectric patches that act as sensor, actuator and exciter respectively. A compensated inverse PID controller has been designed and developed to damp first three modes of vibration. Controllers have been designed for each mode and these are later combined in parallel to damp any of the three modes. Individual controller gives better reduction in sensor output for the second and third modes while the combined controller performs better for the first mode. Simulation studies are carried out using MATLAB. These results are compared and verified experimentally and the real-time implementation is carried out with xPC-target toolbox in MATLA

Fuzzy-PID controller for semi-active vibration control using magnetorheological fluid damper

Magnetorheological (MR) dampers are considered as excellent prospect to the vibration control in automotive engineering. To overcome the effect from road disturbances many control algorithms have been developed and opted to control the vibration of the car. In this study, the methodology adopted to get a control structure is based on the experimental results. Experiments have been conducted to establish the behaviour of the MR damper. In this paper, the behavior of MR damper is studied and used in implementing vibration control. The force-displacement and force-velocity response with varying current has been established for the MR damper. The force for the upward motion and downward motion of damper piston is found increasing with current and velocity. In the cycle mode which is the combination of upward and downward motion of the piston, the force having hysteresis behaviour is found increasing with current. Results of this study may serve to aid in the modelling of MR damper for control applications

Active vibration control using piezoelectric actuator: implementation of ant colony optimization technique in virtual experimentation

This paper demonstrates the implementation of virtual experiment using COMSOL Mutiphysics – MATLAB integration for optimization in active vibration control system. The benchmark model is a simply supported thin plate excited and attenuated by two piezoelectric patches. Instead of using equation-based modeling to represent the system, optimization of the sensor-actuator location and controller gains are conducted directly on the finite element model in COMSOL Multiphysics via Livelink for MATLAB function. The optimization is based on the average energy reduction across a frequency range between 11 Hz to 50 Hz, which covers the first three modes. It is found that the maximum attenuation achieved is 68.31% using optimal values of ensor -actuator location and controller gains