Papers by Keyword: Error Measurement

Abstract: In the paper, an approach for parameter identification during regular movements of servo axes is discussed. In contrast to the usual case, where test signals are applied to the process, there is no deterministic excitation present in this manner. Consequently, the accuracy of the identified parameter depends on the available excitation and needs to be assessed after the identification is completed. Considering that, several methods of error calculation and similarity measurement are presented in the paper and discussed for the specific use case of non-invasive parameter identification.

Abstract: This paper developed a turntable positioning error measurement system based on machine vision. The system consists of image acquisition devices, the image acquisition card, computer and data processing software and other components. Among them, the image acquisition devices consisted of two digital CCD cameras and two microscope objectives. The image acquisition devices capture images of fixture fixed on the turntable in horizontal and vertical direction. Then, the collected images are processed by adopting the filtering method, binarization method, edge detection method, calibration method and other steps. The high-accuracy measure of turntables positioning errors is realized, and the error histogram is drawn. Theoretical analysis and experimental results show that the method is correct and feasible.

Abstract: With the increasing requirements of the machining accuracy of CNC machine tools, the impact of thermal deformation is growing. Thermal error compensation technology can predict and compensate the thermal errors in real-time, and improve the machining accuracy of the machine tool. In this paper, the research objects of thermal error compensation is expanded to the volumetric error of the machine tool, the volumetric error modeling of a three-axis machine tool is fulfilled and a compensator is developed for the compensation experiment, which provides scientific basis for the improvement of the machining accuracy.

Abstract: Basis on the analysis of the plate flatness detection, some problems of the traditional flatness measuring method is pointed out and the 3D reconstruction method of flatness is proposed. The digital flatness measuring instrument is designed, and the measured plane information is entered into the computer, then the data processing is completed by software, which solves the problem of amounts of data, complicated calculation and low accuracy of traditional measurement method. The 3D reconstruction of surface morphology is completed by OpenGL and BCB, to make the information of flatness more sufficient and intuitive. To verify the validity of the measurement, use the flatness function module of dual-frequency laser interferometer to evaluate the instrument accuracy, the results show that it reaches the expected precision index.

Abstract: This paper first introduces the trajectory mode of the each error source in detection the roundness error of NC machine tool. The error separation algorithm is derived according to the relationship between the various error sources and the machine tool motion trajectory. Based on the two testing link under different condition, comparing the test results under two testing conditions, the main error source of NC machine tools is further analyzed. According to the merits and demerits of the two kinds of detection methods, the different round error detection method can be chosen under different occasions.

Abstract: In this paper, a compensation method of coupling error used in high-precision turning machine is proposed. The laser interferometer and optical lens are used for measuring coupling error of machine; the precise motion characteristic of the micro-adjusting mechanism is utilized for compensating. In the end, this method is verified by experiments, and the results show that the motion accuracy of the test bench has been effectively improved.

Abstract: Error compensation is an effective and inexpensive way that can further enhance the machining accuracy of a multi-axis machine tool. The volumetric error measurement method is an essential of the error compensation method. The measurement of volumetric errors of a 5-axis machine tool is very difficult to be conducted due to its complexity. In this study, a volumetric-error measurement method using telescoping ball-bar was developed for the three major types of 5-axis machines. With the use of the three derived error models and the two-step measurement procedures, the method can quickly determine the volumetric errors of the three types of 5-axis machine tools. Comparing to the measurement methods currently used in industry, the proposed method provides the advantages of low cost, easy setup, and high efficiency.

Abstract: Firstly, structure component of the 6PUS-UPS PMT (Parallel Machine Tool) was introduced. Secondly, errors during the machine tool debugging were analyzed and measured, and those determined by the 6PUS-UPS PMT structure character were focused on, including the clearance error between the slider and the guide way, the vibration error and the verticality error and so on. Lastly, the verticality error was measured using the digital display micrometer and the frame level, which has great influence on the 6PUS-UPS PMT precision

Abstract: To further enhance the accuracy of a micro milling process, an effective error measurement method and error compensation method are necessary. An on-machine vision-based error measurement method integrating image re-constructive technology, camera pixel correction, and model comparison algorithm to provide the capability of non-contact measurement for micro-machined workpiece error was developed. With use of Canny Edge Detection algorithm and camera pixel calibration, the edge of the contour of a machined workpiece can be identified and used to re-construct the actual shape of the workpiece. The actual shape will then be compared to the theoretical shape of the workpiece. To prove the feasibility of the proposed methods and system, experiments were conducted. The results have shown the success of enhacing machining accuracy for a micro milling process.

Abstract: Measurement method using telescoping ball-bar that can directly determine the volumetric errors of three main types of five-axis machine tools was developed. Adopting Single Socket method, and the method following the defined two-step measurements sequence and incorporating with derived error models, can quickly determine the five degrees-of-freedom (DOF) volumetric errors of five-axis machine tools. Comparing to most of the current used measurement methods, the proposed method provides the advantages of low cost, high efficiency, easy setup, and high accuracy.