Prasitmeeboon, Pitcha
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Item type:Publication, Min-max merged with quadratic cost for repetitive control of minimum phase systems(2018-06-08)Repetitive control (RC) is an effective method to eliminate the effects of a periodic disturbance to a feedback control system. Applications of RC include an active vibration isolation mount in spacecraft, servomechanisms, and robotic manipulators. Previous work develops a repetitive controller design for non-minimum phase systems using optimization in frequency domain. The objective of the design is to minimize the maximum error merged with quadratic cost, formulated as quadratically constrained linear programming. This work studies how to make use of the Min-Max merged with quadratic cost design for minimum phase systems. An understanding of how to make design choices for the interchange between Min-Max and quadratic cost for each frequency range is developed. The performance of the proposed design choice evaluated by using a simulation of a commercial robot link shows that the design can produce an effective compensator design for minimum phase systems. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Defect detection of particleboards by visual analysis and machine learning(2019-07-01); Yau, HenryParticleboards may exhibit several defect types caused by a variety of sources during the manufacturing process. It is essential to quickly determine when a defect is present and localize the fault so that the board can either be fixed or discarded. Several methods have been already been developed to address this issue to varying degrees of success. In this work, a novel process is presented which quickly determines whether a defect exists or not using traditional machine learning techniques on a bivariate color histogram of the particleboard and then localize the defect using automated image manipulation techniques. The workflow of quickly determining if a defect is present then using a more computationally intensive technique to localize and classify the defect can be extended to use other methods or even to other processes. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Design of Repetitive Controller Using Optimization in Frequency Domain with Maximum Gain Constraints(2018-09-18)Spacecraft inherently have rotating parts such as the momentum wheels, reaction wheels or CMGs. Slight imbalances can produce vibrations that disturb fine pointing equipment. Repetitive control (RC) can be applied on an active vibration isolation to eliminate the effect of such periodic disturbances. An effective RC design method based on optimization in frequency domain was presented. In situations that a system needs large amount of correction, a compensator with high gains can generate a command that exceeds the capacity of the equipment. The error continues to grow and the system will become unstable. A method to reduce the magnitude of the compensator gains available in literature requires a weighting function that is difficult to design. This paper presents an alternative method to design an RC compensator that can limit the maximum magnitude of compensator gains. Simulation results show that the proposed method is more effective than the existing method. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Simple level control plant model using LabVIEW(2018-01-06); ; This paper presents a design and implementation of water level control plant model used as learning aid in the level control process. The plant model consists of a differential pressure transmitter, Frequency Inverter and Proportional-Integral-Derivative (PID) Controller. The differential pressure transmitter is used for measuring liquid level in process tank, and Inverter is employed to adjust the inlet flow of the tank. The PID controller can be configured by a PID function of LabVIEW program. In addition, two flow transmitters and solenoid valve are also installed to monitor the flow rate and/or cascade additional control loop in the future. The procedure to implement the plant model are divided into 5 steps: Controlling liquid level in cylinder tank with 10 cm in diameter and 40 cm in height were specified, sizing and selecting instruments needed, implementing the plant model according to the designed Piping & Instrument (P&I) diagram and Solid Work drawing, designing the control program and human machine interface (HMI) screen in LabVIEW program and the control parameters for single-loop controller modeled TTM-007, and evaluating the performances of implemented plant model. The experimental results of step changes of set point are also included and compared to the result from the plant using a commercially available single loop controller.