In this article, we present an experimental study on the speed stability of a spindle driven by a hydraulic motor, which is controlled by a proportional valve, through a V-belt transmission. The research includes the dynamic modeling of the transmission cluster and the transmission from the hydraulic motor to the working shaft via V-belt mechanism, together with the establishment of a mathematical model and fuzzy self-tuning PID controller model. In the model, the V-belt is assumed as an elastic module, and the friction coefficient and mass inertia moment of the hydraulic motor are considered as constant. The Matlab software is used to simulate the speed response of the hydraulic motor to the working shaft. Based on theoretical study, we resemble the experimental system and determine the parameters for the fuzzy self-tuning PID controller. We conduct experiment and investigate the speed stability of the working shaft from 300 to 1100 (rpm) based on transient response parameters such as the time delay, the setting time, the overshoot, and the rotation error at steady state. Thereby, in this study, the simulation and the experiment results are compared and evaluated regarding the speed stability of the working shaft driven by hydraulic motor transmitted through V-belt mechanism. The findings show the speed controllability by using proportional valve to manipulate the oil flow and applying a self-tuning PID controller to achieve very good results such as the error difference of 0.001 to 0.036%, the delay of 0.01 to 0.02 seconds, no overshoot, and the settling error less than 5% compared to the set values. On the other hand, we include the effect of the oil temperature of 40 to 80°C on the working shaft speed (500, 900 rpm) in this study and derive that the system works well at temperature range of 40 to 70°C. On these findings, we propose the applicability of this system on the current machinery cutters. In addition, we verify the effects of the hydraulic drive for main shaft, controlled by fuzzy PID, by comparison of the roughness of the machining work piece with respect to the one using the 3-phase motor drive.
This paper presents a method to reconstruct a B-spline surface from a quadrangular mesh, using an inverse CatmullClark subdivision. We want to minimize the surface contraction due to the approximating subdivision scheme. We introduce geometrical operations which minimize the impact of the subdivision approximation and can be used in the parametric surface reconstruction. The quality of the method is evaluated by criteria of distances, curvatures or computing time on experimental results.
This paper presents a Takagi-Sugeno fuzzy descriptor approach for nonlinear control of a 2-DoF serial manipulator. The design goal is to achieve high tracking performance in case of circular trajectory while significantly reducing the numerical complexity of the designed controller through an original robust control scheme. Based on Lyapunov stability theory, the control design is reformulated as an LMI (linear matrix inequality) optimization which can be easily solved with available solvers. Simulation results carried out with SimMechanics environment clearly demonstrate the effectiveness of the proposed control approach.
Detection of gearing and bearing faults using vibration signals has been widely used for decades. A lot of methods of vibration signal processing for fault detection have been used, such as fast Fourier transform, Hilbert transform, wavelet and wavelet packet transform. In recent years, a new method for vibration signal processing, combining Hilbert transform and wavelet packet appeared, and has become an effective method to extract modulating signal and help to detect the early gearing and bearing faults. The article deals with the use of the combination of wavelet packet method and Hilbert transform for processing acoustic signals to identify bearing and gearing faults in a two-stage gearbox test rig. Three simultaneous faults are made: a chipped tooth on the input pinion, a pitting tooth on the output gear and a pitting (spall) on the outer race of a rolling bearing on output shaft. By comparison of the processed acoustic signals of normal and faulty gearbox, these three faults can be exactly detected.
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