Papers by Keyword: LVDT

Abstract: The volume changes during solidification of Nodular Cast Iron (NCI) in the sand mold studied using Linear Variable Differential Transformer (LVDT). Both hypo- and hyper-eutectic compositions are considered by adjusting the carbon fraction in the composition during the experimental studies. The microstructural analysis and measurements are taken from the samples to evaluate the different phases present, the nodule count and size distributions. At the beginning of solidification, the experimental result shows the volume change is negligible. During the eutectic growth, the samples expand until the end of solidification. The displacement measurement shows the expansion continued when solidification finished. The volume change studies during solidification indicate that as the carbon fraction increases the volume expansion decreases. On the other hand, it is found that the pore fraction decreases as the volume expansion decreases. The fraction of primary austenite decreases as the fraction of carbon increases, and that leads to having a lower pore fraction.

Abstract: In this paper we propose the gripper handle real-time based embedded system for operating robot manipulator. The general gripper has only a simple function and has also I/O module. Thus general gripper and position based robot controller combination is not suitable for precision process operation, IT assembly process. In order to give various functions and intelligence to the gripper, it is necessary to have an embedded controller that real-time guarantees. The proposed embedded system have five component that handle the pose of the gripper, measure the pose and translation of gripper, motoring the gripping tip, operate the stiffness of the gripper and communicate with Ethernet interface to the external robot controller. The external robot interface parts are supported to communicate with various external robot maker, KUKA, DENSO, ROBOSTAR etc. The validation and functional ability is tested on the LAB environment.

Abstract: Inoculation of casting used to improve the microstructure and the properties of the component. Depending upon the area of application, gray cast iron has different microstructure and mechanical properties. The type and amount of the inoculation result in shape and orientation differences of the flake graphite. The Linear Variable Differential Transformer (LVDT) shows a variation in displacements change during the solidification. Temperature measurement used to analyze cooling curves and microstructural analysis of sample to examine the physical differences. Thermal analysis compared with the experimental results and microstructural study for describing the variation in area fraction and shape of graphite. The experimental result indicates contraction in austenite formation region, and expansion in eutectic formation region. The effect of the inoculant and the superheat temperature shows a variation in degree of expansion/contraction and cooling rates of the experiments. The comparisons between the experimental and the theoretical results have been done. Combining the theoretical and experimental results, it resembles a difference in eutectic formation region, and it needs carful investigation in future works.

Abstract: A cotton sliver detection sensor is designed, which is different from the traditional roller detection system. Firstly the lever enlarges the change of thickness of cotton sliver into a large amount of displacement, and then the LVDT detects this displacement, and finally the signal transmission module based on AD698 converts the detected signal of the LVDT into a voltage ranging from 0V to 10V. The experiments show that the sensor has good linearity and resolution. The design is not only with lower mechanical inertia and simpler signal processing circuit, but also solving the problem that in the face of processing technologies change, sliver sensor with embossing roller and ladder roller, need to replace the different detection roller.

Abstract: To assure product quality, an early warning and inspection system to predict the variation (trend) of a products quality (i.e. the product thickness) in the manufacturing process is necessary. Here, a manual online measurement of a production line installed with an online automatic warning system that will prevent manually accumulated errors from occurring is presented. Using this system, a quality trend profile will be made. The abnormal trend distribution will be obtained by randomly selecting the period of the quality trend profile and translating it into a time distribution bar chart. The monitoring online system will be pre-warned via the abnormal trend distribution. A products thickness can be obtained using a linear variable differential transformer (LVDT). The analogue signal will be transmitted to the AD converter of the PLCs analogue input channel. The digital signal will be transmitted from the series port to the remote PC via the web control unit. A profile of the products thickness measured by the LVDT will be monitored online and dynamically exhibited in the web-based remote system by using an embedded Javascript, an HTML, and a web control unit. The upper/lower thresholds will be preset in the product thickness profile. In addition, the quality monitoring system will be pre-warned via the time distribution bar chart when the abnormal trend distribution occurs. Consequently, the web-base monitoring system can be extended to remotely connect to all the LVDT devices.

Abstract: According to the algorithms of traditional Linear Variable Differential Transformers (LVDTs) could not represent the performances of the Layer Wound Linear Variable Differential Transformers (Layer Wound LVDTs), new computational algorithms were presented in this paper. Based on magnetic circuit theory, the calculations for the Layer Wound LVDT’s magnetic circuit reluctance, self-inductance, mutual inductance, output voltage and sensitivity are provided. Simulation analysis and experimental tests were used to verify the calculations. The results show that the calculations and equations can accurately express the performance of the Layer Wound LVDTs.

Abstract: The phase transformation during continuous cooling in low carbon steel has been widely measured by dilatometer using the lever rule. However, the concept of lever rule has several limitations. In low carbon steels, it is observed that overlapped transformation region of multi-phase and inflection point of small amount of low temperature phase is hardly differentiated. First derivatives of LVDT during continuous cooling could be better way to identify the inflection point and transformation region of phases (especially low temperature phase). Furthermore, first derivative of LVDT could be expressed as the lattice parameter and phase fraction due to temperature. Therefore, phase transformation behavior is simulated by the analysis of first derivative of LVDT using Avrami equation from experimental LVDT. As a result, the start, finish temperature and the amount of each phase are determined. The method is also confirmed by OM and SEM.

Abstract: This paper integrated multi-domain knowledge of electronics, optics, control as well as precision measurement, and proposing a high resolution subdividing electronics module to the sinusoidal encoder output of a positioning motor, such that the module can not only be used as a counter for linear and/or angular measurements, but also subdivide the periods of the sinusoidal encoder signals up to 1600 times. From the results of experiment test it can be seen that the whole module is suitable for those applications requiring high-resolution encoder, nanometer measurement as well as fast data acquisition with phase tolerance of ± 45°.

Abstract: The key point of this research is to use Linear Velocity Transducer (LVT) to detect the vertical velocity of the stylus probe for the inner-loop damping and transient control of a force actuator. This improvement has been verified by MATLAB simulation and practical implementation of a surface profiler to reduce the hysteresis effect of the force actuator.

Abstract: Most domestic fossil power plants have exceeded 100,000hours of operation with the severe operating condition. Also, cyclic operation of the plant subjects the piping system to mechanical and thermal fatigue mechanisms and poor of defective support assemblies can impose massive loads onto the piping system and induce unstable piping displacement. In order to prevent the serious damage and failure of the piping system in fossil power plants, 3-dimensional displacement measurement system was developed for the on-line monitoring. Displacement measurement system was developed with LVDT and rotary encoder type sensors. This system was installed and operated on a real power plant successfully.